US20070169704A1

US20070169704A1 - Apparatus for shielding process chamber port having dual zone and optical access features

Info

Publication number: US20070169704A1
Application number: US11/472,017
Authority: US
Inventors: Fangli Hao; Leonard Sharpless; Harmeet Singh
Original assignee: Lam Research Corp
Current assignee: Lam Research Corp
Priority date: 2006-01-26
Filing date: 2006-06-20
Publication date: 2007-07-26
Also published as: CN101042978A; TW200739713A; US7685965B1

Abstract

A port in a window member provides first access to a process chamber interior for gas injection and second optical access for process analysis and measurement. Plasma-induced etching and deposition in a bore of a gas injector integral with the window member is reduced by a grounded shield surrounding an access region, and coatings reduce particle flaking from walls of a first clear optical aperture of the injector and from a second clear optical aperture of a gas and optical access fitting,. The shield surrounds the region, and is configured with couplers to hold the gas and optical access fitting to the window member for access to the injector. The couplers compress seals so that a gas bore in the fitting is sealed to a plenum of the injector, while allowing optical access into the chamber through the first clear optical aperture and the second clear optical aperture.

Description

RELATED APPLICATION

This application is a continuation-in-part of U.S. patent application Ser. No. 11/341,079, filed Jan. 26, 2006 for “Apparatus For Shielding Process Chamber Port”, in the names of Fangli J. Hao, John E. Daugherty, and Allan K. Ronne (the “Prior Application”). The disclosure of the Prior Application is incorporated by reference. The benefit of the filing date of the Prior Application is claimed under 35 U.S.C. Section 120.

BACKGROUND

1. Field of the Invention
The present invention relates generally to semiconductor manufacturing and, more particularly, to apparatus for shielding access regions of process chambers from electrical fields, wherein the access regions allow access to semiconductor manufacturing chambers, the electric fields are applied to the chambers adjacent to the access regions, and access openings in the access regions provide access for exemplary gas injectors and process analysis and measurement tools.
2. Description of the Related Art
Vacuum processing chambers have been used for etching materials from substrates and for deposition of materials onto substrates, and the substrates have been semiconductor wafers, for example. U.S. Pat. No. 6,230,651 to Ni et al. issued May 15, 2001 and assigned to Lam Research Corporation, the assignee of the present application, is incorporated herein by reference and illustrates an opening, or port, in a dielectric window at a top of a processing chamber to provide access to an interior of the processing chamber, for etching and other processing of semiconductor substrates, for example. For large diameter substrates, center gas injection was said to ensure uniform etching and deposition, for example, thus improving the access to such processing chambers.
However, as industry standards have increased, further improvements are required to provide even better access to such processing chambers. For example, there is a need to monitor the processes in the chambers, which requires chamber access in addition to access for gas supply. When the monitoring relies on optical data, a clear optical aperture must extend through the dielectric window. Difficulties arise, however, when the clear optical aperture is physically open to the chamber, because plasma may form in the clear optical aperture. Such plasma formation relates to a threshold electric field strength required to initiate a plasma, which threshold strength is based on gas pressure in and the diameter of a passage, or bore, used to supply the gas to the chamber. Plasma formation in a gas supply bore is generally reduced by reducing the diameter of the bore because the gas pressure tends to be controlled by process requirements. However, analysis by the applicants of the present application indicates that when there is dual use of a clear optical aperture (i.e., use for both optical and gas supply functions) the dual use presents conflicting requirements. That is, for the aspect of facilitating monitoring the optical data, there is a need to increase the diameter of the clear optical aperture. For example, in providing optical access for spectroscopic observation of chamber processes, the diameter of the clear optical aperture must generally be not less than about one-half inch, for example, and it is highly desirable to use an aperture as large as possible. This diameter may be described as a minimum diameter that is required to enable proper access to the optical data that originates in the chamber, and is referred to herein as the “minimum diameter of the clear optical aperture”. This analysis also indicates that for the gas supply aspect of the dual use there is a need for a relatively small diameter (significantly less than 0.5 inch) of each gas bore for gas supply to the chamber, for avoiding plasma formation, for example. This analysis also indicates that to facilitate the dual use, an optical window must be used to seal the clear optical aperture so as to maintain a vacuum in the processing chamber, and that the optical window should be mounted at a location at which the strength of the electric field is substantially reduced, to prevent sputtering of the optical window (which creates aluminum-containing contamination), and to prevent deposition onto the optical window. Thus, applicants' analysis indicates that there is not only the minimum diameter of the clear optical aperture in conflict with the need for small diameter gas bores, but a minimum length of the clear optical aperture necessary to avoid such contamination and damage to the optical window that facilitates the dual use.
This exemplary 0.5 inch minimum diameter of the clear optical aperture compares to gas bore passages of 0.4 mm provided in shielded gas inlets described, for example, in U.S. Pat. No. 6,500,299, issued 12/3/102 to Mett, et al. Although multiple ones of such passages are provided through grains of dielectric materials such as ceramics, with the 0.4 mm diameter size, such passages are not suitable for providing clear optical access for the exemplary spectroscopic observation of chamber processes. Moreover, to mount such passages of a gas bore inside a metal cup and to insert the cup in the side wall of a process chamber as described in the Mett et al. Patent, would undesirably subject the metal cup to the plasma in the chamber, for example, and introduce problems in sealing the metal cup to the wall of the process chamber.
In view of the foregoing, there is a need for apparatus providing further improvements in accessing processing chambers. The need is for improved ways to provide multiple access (e.g., gas supply and optical access) to a process chamber. This need includes providing such access when the optical access is subject to the conflicting requirements of a relatively large minimum diameter of the clear optical aperture (for the optical function) and of a relatively small diameter of one or more gas bores for gas supply to the chamber (for avoiding plasma formation), for example.

SUMMARY

Broadly speaking, embodiments of the present invention fill these needs by providing apparatus for shielding a process chamber port having dual zone and optical access features, the shielding being from electrical fields, wherein the access region allows access to a semiconductor manufacturing chamber, the electric fields are applied to the chamber adjacent to the access region, and access openings in the access regions provide access for exemplary gas injectors and process analysis and measurement tools. Such apparatus may include configurations of an access region of a process chamber to allow dual supply of process gas to the chamber, and to provide a first clear optical aperture for optical access through a window of the chamber. Such apparatus may also provide a combination of protection of a dual gas supply fitting and the first clear optical aperture from the electric field established by the coil that surrounds the first clear optical aperture and the fitting. A shield may be configured to extend into the window to provide such protection for a first section of the first clear optical aperture with a remaining second section of the first clear optical aperture extending toward the processing chamber. The remaining section may be protectively coated to provide such protection from the electric field and provide the minimum length of the clear optical aperture. A second clear optical aperture is provided in the fitting to extend the first aperture away from the electric field. The shield and additional coatings may protect the second clear optical aperture from the electric field, and an optical window may close the second clear optical aperture at a location at which the strength of the electric field is substantially reduced, to prevent sputtering of the optical window (which creates aluminum-containing contamination), and to prevent deposition onto the optical window.
Embodiments of the present invention may include a window for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window. The window may be a window member configured with outer and chamber sides and an annular groove extending from the outer side into the member parallel to the axis. The annular groove defines a first section of the access region to be protected from the electric field, and the window member is further configured with a clear optical aperture having an annular wall configured with a length between the outer side and the chamber side. The clear optical aperture may be partly surrounded by the annular groove and may be further configured with a diameter. A coating of a material such as yttrium oxide is provided on the annular wall of the clear optical aperture. The annular wall with the coating having an inner coating diameter that is substantially the same as a value of the length of the clear optical aperture in the window member.
An other embodiment of the present invention may include a multi-function process chamber window assembly for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window, for admitting at least one gas to the process chamber, and for providing optical access to the chamber. An annular shield may have a length extending parallel to an axis of the region and be fabricated from material adapted to substantially block the electric field. A window member is configured with respect to the access region axis, the member being configured with outer and chamber sides and an annular groove extending from the outer side into the member. The groove defines a first section of the access region to be protected from the electric field. The groove is configured to receive a portion of the shield to protect the first section of the access region from the electric field. The groove receives the annular shield, and the shield extends out of the groove and away from the outer side so that a second section of the access region is defined within the annular shield. The annular shield protects the second section from the electric field. The window member is further configured with a first clear optical aperture defined by a first annular wall configured with a length between the outer side and the chamber side. The first clear optical aperture is partly surrounded by the annular groove, and the first clear optical aperture is further configured with a diameter for clear optical access. A coating is provided on the first annular wall. The first annular wall with the coating has an inner coating diameter that is substantially the same as a value of the axial length of the first clear optical aperture. The coating protects the first clear optical aperture from effects of the electric field so that the protection extends past the shield in the annular groove to the chamber side of the window member.
Yet an other embodiment of the present invention may include a multi-function process chamber window assembly for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window while providing at least two gas inlets to the process chamber and allowing optical access to the chamber. The assembly may include an integrated shield and gas supply unit for protecting the access region from the electric field. The unit may be configured with a thin annular protrusion at a first end and with an annular body that is thicker than the protrusion. The body may be further configured to extend to a second end. The body may be further configured with a first annular wall defining a unit clear optical aperture extending from the first end to the second end. A further body configuration may provide a first gas supply bore extending and intersecting the unit clear optical aperture adjacent to the first end. The body may be further configured with a first coupler and the unit fabricated from material adapted to substantially block the electric field so that the unit clear optical aperture is protected from the electric field. A window member of the assembly may be configured with outer and chamber sides and a groove extending from the outer side into the member. The groove is configured to receive the thin annular protrusion to protect a first section of the access region from the electric field. The member may be further configured with a second coupler configured to cooperate with the first coupler to hold the protrusion in the groove with the unit extending away from the outer side of the member so that a second section of the access region is defined by and is protected by the body from the electric field. The window member may be further configured with a window member clear optical aperture having a second annular wall configured with a length between the outer side and the chamber side. The window member clear optical aperture is partly surrounded by the thin annular protrusion received in the annular groove. The window member clear optical aperture may be further configured with a diameter. A coating is provided on the second annular wall. The second annular wall with the coating has an inner coating diameter that is substantially the same as a value of the axial length of the window member clear optical aperture. The coating protects the window member clear optical aperture from the electric field.
It will be obvious, however, to one skilled in the art, that embodiments of the present invention may be practiced without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to obscure the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The embodiments of the present invention will be readily understood by reference to the following detailed description in conjunction with the accompanying drawings in which like reference numerals designate like structural elements, and wherein:
FIG. 1 is a schematic view of an embodiment of an apparatus of the present invention for protecting an access region into a process chamber from an electric field;
FIG. 2A is a side cross-sectional view of an embodiment of a window of the present invention for protecting an access region into the process chamber from the electric field generated adjacent to the window;
FIG. 2B is a plan view of the window embodiment shown in FIG. 2A, illustrating a groove for a shield, a gas bore and a first clear optical aperture;
FIG. 2C is a side cross-sectional view of another embodiment of the window of the present invention, illustrating a projection on the window;
FIG. 3A is a side cross-sectional view of the window embodiment of FIG. 2B assembled with a shield and with an embodiment of a fitting separate from the shield;
FIG. 3B is a cross-sectional view taken along line 3B-3B in FIG. 3A, illustrating the assembled fitting of FIG. 3A configured with seals;
FIG. 3C is a cross-sectional view taken along line 3C-3C in FIG. 3A, illustrating the assembled fitting of FIG. 3A configured with an embodiment of an optical window;
FIG. 3D is a three-dimensional view of the fitting of FIG. 3A, showing a port for access to the embodiment of the optical window;
FIG. 4A is a side cross-sectional view of the assembled shield and embodiment of the fitting separate from the shield, illustrating another embodiment of the optical window;
FIG. 4B is a cross-sectional view taken along line 4B-4B in FIG. 4A, showing the FIG. 4A embodiment of the optical window;
FIG. 4C is a cross-sectional view taken along line 4C-4C in FIG. 4A, showing the FIG. 4A embodiment of the fitting with a gas inlet to gas bores of the fitting;
FIG. 5A is a side cross-sectional view showing the chamber window embodiment of FIG. 2A assembled with a shield and multi-function fitting integral with the shield, with one embodiment of an optical window near the chamber window; and
FIG. 5B is a side cross-sectional view of the shield and multi-function fitting integral with the shield of FIG. 5A, illustrating the assembled fitting of FIG. 5A configured with the FIG. 4A embodiment of the optical window.
Other aspects and advantages of embodiments of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of embodiments of the present invention.

DETAILED DESCRIPTION

Embodiments of an invention are described for apparatus, and for a multi-function process chamber window assembly, for protecting an access region for access to a process chamber from an electric field generated adjacent to a window of the chamber. The protecting may be by shielding access openings in the window from electrical fields, wherein the openings allow multiple types of access to semiconductor manufacturing chambers. For an opening that is a gas bore for injecting process gas into the chamber, the protection is from the electric field. For an opening that is a clear optical aperture providing optical access into the chamber, the protection is also from effects of the electric field, and this protection may extend past a shield so that an entire length of the clear optical aperture is protected.
In one embodiment of the present invention, a window member is configured with respect to an access region axis, the member being configured with an annular groove extending into the member parallel to the axis. The annular groove may be configured to define a first section of the access region to be protected from the electric field. The window member may be further configured with a clear optical aperture having an annular wall extending co-axially with the axis and configured with an axial length between the outer side and the chamber side. The clear optical aperture may be partly surrounded by the annular groove and may be further configured with a diameter. An Yttrium oxide coating may be provided on the annular wall of the clear optical aperture. The annular wall with the coating may have an inner coating diameter that is substantially the same as a value of the axial length of the clear optical aperture.
In another embodiment of the present invention, a multi-function process chamber window assembly is provided for protecting an access region for access to a process chamber. The protection is from an electric field generated adjacent to the process chamber window. The window assembly may admit at least one gas to the process chamber and may provide optical access to the chamber. An annular shield having a length extending parallel to an axis region axis may be fabricated from material adapted to substantially block the electric field. A window member may be configured with respect to the access region axis. The member may also be configured with an annular groove extending parallel to the axis to define a first section of the access region to be protected from the electric field. The groove may be configured to receive a portion of the shield to protect the first section of the access region from the electric field. When the groove receives the annular shield, the shield may extend out of the groove so that a second section of the access region is defined within the annular shield. The annular shield may be configured to protect the second section from the electric field. The window member may be further configured with a first clear optical aperture defined by a first annular wall extending co-axially with the axis and configured with an axial length between the outer side and the chamber side. The first clear optical aperture may be partly surrounded by the annular groove and may be further configured with a diameter for clear optical access. An exemplary Yttrium oxide coating on the first annular wall may have an inner coating diameter that is substantially the same as a value of the axial length of the first clear optical aperture. The exemplary Yttrium oxide coating protects the first clear optical aperture from effects of the electric field so that the protection extends past the shield in the annular groove to the chamber side of the window member.
FIG. 1 shows a schematic view of an apparatus 40 of the present invention for protecting an access region for access to a process chamber. The protection may be from an electric field generated adjacent to a window of the chamber. The access region may allow access to a semiconductor manufacturing process chamber, for example. The electric field is applied to the process chamber adjacent to the access region for exemplary gas injectors and process analysis and measurement tools. FIG. 1 shows the apparatus 40 including a vacuum processing chamber 42 having a substrate holder 44 providing a suitable clamping force to a substrate 46. The top of the chamber 42 may be provided with a dielectric window 48. One of many access openings, or ports, 50 is shown schematically as being provided in the window 48 to permit access to the interior of the chamber 42.
FIG. 2A is an enlarged cross-sectional view showing the window 48 as a process chamber window with exemplary ports 50, and showing spaced vertical dot-dot-dash lines defining an exemplary cylindrical access region 52. The access region may thus be a three-dimensional volume within an exemplary hollow cylinder defined by the lines. In the embodiment of the access region 52 shown in FIG. 2A, the access region 52 extends into the window 48, as described below. The portion of the access region extending into the window 48 may be referred to as a first section (see bracket 52-1). The access region is also shown extending above the window 48, and the portion of the access region 52 above the window 48 may be referred to as a second section (see bracket 52-2). For other embodiments of the access region 52, similar lines may also define another three-dimensional shape, for example, and the other embodiment of the access region 52 would also be defined by such other three-dimensional shape.
FIG. 1 also schematically shows the chamber 42 provided with facilities 54 that require access to the chamber 48 via the access region 52. For example, the facilities 54 may provide access to the chamber 42 for process analysis or measurement as described below, which may be referred to as optical access. The facilities 54 may also provide access to the chamber 42 to facilitate conducting deposition or etching processes in the chamber 42, such as by supplying process gases to the chamber 42. As one example of the facilities 54, process gas may be supplied from a gas supply through the access region 52 into the chamber 42. With a pump (not shown) reducing the pressure in the chamber 42 for the deposition or etching processes, a source 58 of RF energy with an impedance matching circuit is connected to a coil 60 (see also FIG. 2A) to energize the gas in the chamber and maintain a high density (e.g., 10⁻¹¹to 10⁻¹²ions/cm³) plasma in the chamber 42. The coil 60 may be the type that inductively couples RF energy into the chamber 42 through the window 48 to provide the high density plasma for conducting the deposition or etching processes in the chamber 42. During that coupling, the coil 60 generates an electric field (see exemplary lines 62, FIG. 2A).
FIG. 2A shows that without the use of embodiments of a shield of the present invention, the electric field 62 may extend between turns of the coil 60 above the top of the window 48 and may extend in the window 48 through the ports 50. This generation of the electric field 62 without the use of the shield embodiments of the present invention tends to induce an undesired plasma in the ports 50 within the access region 52. For example, the tendency may be to induce the undesired plasma may be induced in a bore through which the gas is supplied, or in a clear optical aperture through which optical access is provided, as described below. The undesired induced plasma may result in undesired deposition of particles on various parts within the process chamber 42, including on the substrate, which lowers process yield.
The embodiments of the present invention may be used to substantially avoid the problems caused by such undesired plasma induced in the access region 52, while providing other advantages described below. For example, in the enlarged cross-sectional view of FIG. 2A, the window 48 is shown as a multi-function process chamber window with exemplary ports 50. In the FIG. 2A embodiment, the process chamber window 48 is shown in relation to the access region 52 and to sections 52-1 and 52-2. A longitudinal axis X of the window 48 is identified for reference. The window 48 may also be described as a window member, and is shown configured with a groove 64, for example. The groove 64 extends in the window parallel to the axis X to a depth defined by an axial end. FIG. 2B shows that the groove 64 may be configured with an annular shape that that extends circularly around the axis X. The groove 64 is thus configured to surround the access region.
In the use of the embodiment of the window 48 shown in FIG. 2A, the groove 64 may receive a shield 66 (e.g., FIG. 3A) for protecting the access region 52. The protection is from the electric field 62 that is generated as described above. The field 62 is shown in FIG. 2A without the shield embodiment of the present invention, the field 62 extending adjacent to the window 48 in that the field 62 extends above the window, for example. One embodiment of the shield is identified as 66-1 in FIGS. 3A, 3B, and 4A. Another embodiment of the shield is identified as 66-2 in FIGS. 5A and 5B. References to the shield 66 apply to each embodiment. The shield 66 may be fabricated from material adapted to substantially block the electric field 62 from entering the access region 52. Such material and other configuration of the shield 66 provides an electric field-free condition within the shield (i.e., within the access region 52). For the desired protection, the shield 66 may be configured as a three-dimensional structure, such as a cylindrical shield member 68 that has a shape that conforms to that of the access region 52, and the shield 66 is connected to an electrical ground. FIG. 3A shows that with respect to embodiment 66-1, one end of the shield member 68 of the shield 66 is received in the groove 64 to encompass section 52-1 of the access region. Also, the shield member 68 is shown configured to extend in the direction of the X axis out of the groove 64. By reference to FIG. 2B it may be understood that when the shield member 68 is received in the groove 64, the shield member 68 encompasses the access region 52. Also, the location of the bracket 52-2 in FIG. 2C indicates that the shield member 68 encompasses the axial length of the section 52-2 of the access region.
Referring to FIG. 2A, the window 48 is shown further configured with an outer side 70 that is outside of the chamber 42, and with a chamber side 72 that is inside the chamber. The groove 64 extends into the window 48 through the outer side. FIGS. 2A and 2B show the window configured with a plenum 74 that may distribute process gas to the chamber via a plurality of nozzles 76. The plenum is configured with an annular shape having a diameter less than that of the groove 64. The plenum extends to a depth about half way between the outer side 70 and the chamber side 72. FIG. 2B shows (in dashed lines) an exemplary eight of the nozzles 76, which intersect (and thus are connected to) the plenum and extend to the chamber side 72, which is shown as a flat surface parallel to the outer side 70. FIG. 2A shows that a portion of the plenum 74 is encompassed by the groove 64, and is thus in the access region 52. According to the particular process to be conducted in the chamber 42, the window 48 may be made from quartz or ceramic, for example. In the embodiment described herein, the window may be made from ceramic, such as aluminum oxide, which has desired characteristics of tensile strength, thermal conductivity, and chemical resistance. The window may also be made from aluminum nitride, which has desired characteristics of tensile strength and thermal conductivity.
FIGS. 2A and 2B also show the window 48 further configured with a clear optical aperture 78 that may be identified as a first (or window) clear optical aperture to distinguish from other clear optical apertures described below. The first clear optical aperture 78 is configured with an annular wall 80 extending co-axially with the axis X and configured with an axial length L (FIG. 2A) between side 70 and side 72. The first clear optical aperture 78 is partly surrounded by the annular groove 64, and may further be configured with a diameter D1. The diameter D1 may be selected to provide desired access to the chamber, such as optical access by which an observation device (not shown) may view into the chamber for spectroscopy, for example. This may include infrared spectroscopy, for example. Also, plasma properties such as ion flux, e.g., may be measured, or the composition of deposits in the chamber may be determined. For use in the above-described spectroscopic observation, for example, the diameter D1 must be generally not less than about one-half inch. This diameter D1 may correspond to the above-described minimum diameter of the clear optical aperture, that is the minimum diameter that is required to enable proper access to the optical data that originates in the process chamber. The first clear optical aperture 78 may also be used to introduce process gas into the chamber 48. The process gas introduced by the first clear optical aperture 78 may be different from the gas supplied by the plenum 74, for example, and may vary according to the type of processing to be done in the chamber.
FIGS. 2A and 2B also show the annular wall 80 provided with a layer, such as a coating, 82. The coating 82 has an inner coating diameter that is substantially the same as a value of the axial length L of the clear optical aperture 78. The coating 82 may be of a type that does not readily combine with chamber gases, and especially not with fluorine. For example, the clear optical aperture 78 is open to the chamber, thus the plasma that is generated in the chamber 42 may enter the clear optical aperture 78. Even though the shield 66 and other shield embodiments (described below) are configured to substantially reduce the strength of the electric field 62 that may extend across the clear optical aperture 78, the reduced-strength electric field may cross clear optical aperture 78 and may interact with the plasma. Without the coating 82, an aluminum-containing ceramic such as aluminum oxide or aluminum nitride, could react with fluorine, for example, to form aluminum fluoride, which will form particles easily removed from the wall 80 during processing inside the chamber, such as by flaking off, which particles would enter the chamber 48. Embodiments of the clear optical aperture 78 having the coating 82 of the type that does not readily combine with chamber gases include coating materials having higher chemical resistance, e.g., to fluorine, than the chemical resistance of the underlying ceramic material. Thus, relatively few of the exemplary aluminum fluoride particles are formed and enter the chamber 48, such that process yield may increase.
Exemplary materials for the coatings 82 that are of the type that do not readily combine with chamber gases, include: yttrium oxide; yttrium oxide with pores sealed with methacylate ester or sealed with another polymer such as PTFE; or cerium oxide; or zirconium oxide; or yttria-stabilized zirconia; or thermally-sprayed aluminum oxide. To sputter a coating 82 of, for example, yttrium oxide requires ion bombardment of high energy, for example, and with the higher chemical resistance, such coating 82 on the first clear optical aperture 78 results in the low rate of aluminum fluoride formation.
An unexpected aspect of the chamber window 48 relates to the above-described minimum diameter of the clear optical aperture. There is an inverse relationship between the value of such diameter D1 and the ability of the window 48 of a minimum thickness to withstand forces at high vacuum. Also, to meet the requirements of the above-described optical access, diameter D1 must not be less than the minimum diameter of the clear optical aperture. Thus the thickness of the window 48 may be the minimum required for adequate strength when the diameter D1 has a value of the minimum diameter of the clear optical aperture. With this in mind, the exemplary 0.5 inch minimum diameter D1 of the clear optical aperture is also a value of an acceptable thickness L of the window 48, and is also an acceptable diameter for the application of the coating 82 to the entire surface of the wall 80. For example, a torch plasma process may be performed in Argon using an yttrium oxide powder. The torch process generates blobs of powder that splat on the surface to be coated. Ideally, the torch plasma process is directed at an angle of ninety-degrees to the surface to be coated. Because the clear optical aperture 78 has the cylindrical wall 80, the ninety-degree direction is not possible. A limitation of the process is to not direct the process at less than 45 degrees. With a 0.5 inch diameter D1 configuration of the optical aperture 78 of the window 48, and at the 45 degree direction, the torch plasma process is effective to direct the coating of yttrium oxide 0.25 inches into the cylinder defined by the wall 80 and have proper adhesion of the coating. As a result, by directing the coating of yttrium oxide 0.25 inches into each end of the cylinder defined by the wall 80, the entire 0.5 inch length L of the cylinder defined by the wall 80 may be provided with the coating 82, and at the same time the diameter requirements of the clear optical apertures for the exemplary spectroscopy, and the window strength requirements, are met.
FIG. 2C shows another embodiment of the window, or window member, 48 in which the chamber side 72 of the window member may be configured with a projection 90 defined by an axially-extending surface 92 and a flat surface 94 parallel to the chamber side. The nozzles 76 intersect the axially-extending surface 92 and provide improved distribution of the gas into the chamber 48.
FIG. 3A shows a further configuration of the plenum 74 for assisting in alignment of the window 48 during assembly with an embodiment 100-1 of a multi-function fitting 100. The window member 48 with the shield 66 and the fitting 100 combine to define an assembly. The plenum 74 is configured with a first pin hole, or pin bore, 102 centered on the axis of the annular plenum. The first pin bore has a diameter larger than the width of the plenum 74 and defines a location for alignment with the fitting 100. The fitting is configured with a body 101 provided with a gas bore, or conduit, 104 that is configured to supply process gas to the plenum 74. The body 101 is further configured with a second pin hole, or pin bore, 106 coaxial with the gas bore 104, and having a diameter larger than the diameter of the gas bore 104. The diameter of the bore 106 may be equal to the diameter of the first pin bore 102. In assembly of the window 48 with the fitting 100, an alignment pin 108 may be inserted into the second pin hole 106, and the first pin hole 102 aligned with the pin 108 to properly locate the fitting 100 relative to the window 48.
In the above description of FIG. 3A, the embodiment 66-1 of the shield 66 was said to be received in the groove 64 to encompass section 52-1 of the access region. The shield member 68 was said to be shown extending in the direction of the X axis out of the groove 64 to encompass the axial length of the section 52-2 of the access region (as shown by the length of the bracket 52-2 in FIG. 3A). With this in mind, it may be understood that the outer surface 70 outside of the shield 66-1 may be provided with an annular-shaped thin flat shield 109 to block components of the electric field 62 that are parallel to the axis X. The flat shield 109 may be fabricated from the same material as the shield 66, for example. The flat shield 109 is thus mounted under the coil 60 on the outer side 70 of the window 48 and extends outwardly from the shield 66-1. With the flat shield 109 mounted and with the pin 108 used to properly locate the fitting 100 relative to the window 48, the shield 66-1 may also be located and secured relative to the window 48. FIG. 3A shows the shield 66-1 with the cylindrical shield member 68 shaped to conform to that of the access region 52. FIG. 3A also shows the shield 66-1 received in the groove 64 encompassing section 52-1 of the access region, and extending in the direction of the X axis out of the groove 64 to encompass the access region 52, including the axial length of section 52-2 of the access region. The shield 66-1 is configured with a lower mount flange, or first coupling, 110 cooperating with the flat shield 109 and with a fastener to secure the shield member 86 on the flat shield that is on the window member 48. For ease of illustration, the lower mount flange 110 is shown in FIG. 3A only once, it being understood that the flange 110 may be provided at three, for example, locations around the bottom of the shield 66-1.
FIG. 4A shows a top of the shield 66-1 adjacent to a top of the fitting 100-1. The shield 66-1 is there shown configured with an upper mount flange, or second coupling, 112 cooperating with a fitting mount 114 and a fastener to secure the shield member 86 to the fitting 100-1. The respective coupling 112 and mount 114 are pulled together by the fastener so that the fitting is pressed downwardly onto the window member 48, as is described in more detail below. For ease of illustration, the flange 112 is shown in FIG. 4A only once, it being understood that the flange 112 may be provided at three, for example, locations around the top of the shield 66-1. As mounted and secured, the shields 66-1 and 109 are in position to protect the access region 52 from the electric field 62. Also as mounted and secured, the fitting 100-1 is in position to admit at least one gas to the window member 48 for injection into the process chamber 42, and to provide optical access through the first clear optical aperture 78 to the chamber. The fitting 100-1 is thus a multi-function fitting received within the second section 52-2 of the access region 52 defined by the shield 66-1 for protection from the electric field.
FIG. 3A shows one embodiment 100-1 of the fitting in which the body 101 is configured with a second clear optical aperture 116 having a second annular wall 117 extending co-axially with the axis X and vertically aligned with the coated first clear optical aperture 78. The second clear optical aperture 116 serves both to supply gas to the first clear optical aperture 78 and to allow clear optical access to the chamber 42 through the first clear optical aperture 78, e.g., as described above with respect to the exemplary spectroscope (not shown) mounted above the chamber 42 out of the electric field. To facilitate this gas supply, the fitting body 101 is further configured with a gas supply bore, or conduit, 118 initially extending parallel to the axis X and then angles to intersect the second clear optical aperture as described below.
It may be understood that the chamber 42 is operated at a vacuum, such as in a range of 5-400 milliTorr. To maintain the vacuum, the fitting 100-1 is sealed to the window member 48 by a first seal structure 120 that may include seals 122 and 124. In a general sense, the seal structure 120 is between the fitting 100-1 and the window member 48. The seal structure 120 is configured so that in response to the upper and lower couplers 110, 112, and 114 urging the fitting 100-1 toward the window member 48, the seal structure 120 provides an air-tight seal of the fitting 100-1 to the window member 48. Thus, gas flows from the gas supply bore 104 into the annular plenum 74 separately from the respective first and second clear optical apertures 78 and 116. Also, gas flows from the second clear optical aperture 116 into the first clear optical aperture 78 separately from the gas supply bore 104 and from the annular plenum 74. Also, unwanted gases (e.g., atmospheric) do not flow into the chamber.
The seal structure 120 is configured to be mounted in a lower, or window, end 126 of the fitting 100. The end 126 is configured with two spaced annular recesses 128, spaced radially outward from the second clear optical aperture 116. The seals 122 and 124 may be configured with a seal member, such as an O-ring or pad, 130 that may be mounted in each recess 128 and squeezed by the fitting 100-1 that is urged toward the window member 48.
FIG. 3A also shows the lower end 126 configured with one embodiment 132-1 of an optical window assembly 132, and FIG. 4A shows an upper, or second, end 134 of the fitting 100-1 configured with another embodiment 132-2 of the optical window assembly. FIG. 3A shows the optical window assembly 132-1 configured with a seat 136 adjacent to the first seal structure 120 and co-axial with the access region axis X. The seat 136 is configured with a recess 138 to receive a second seal, such as an O-ring, 140. The assembly 132-1 further includes an optical window 142 received in (mounted on) the seat 136. With respect to the optical data that is received from the chamber 42, the optical window 142 may have an optical characteristic of transmitting that optical data out of the second clear optical aperture and into a suitable optical unit, such as a collimator (not shown) for further transmission to the exemplary spectrometer (not shown). For ease of illustration, FIGS. 3A and 3C show the portion of the window 142 to the right of the axis X, it being understood that the window 142 is disk-like (circular). The second seal 140 between the seat 136 and the optical window 142 prevents gas from leaking into and past the second clear optical aperture 116 into the first clear optical aperture 78, while allowing optical access through the second clear optical aperture 116 and through the first clear optical aperture 78 into the chamber 42. A clamp 144 may be used to hold the window 142 against the second seal 140 and the seat 136. To provide access to the optical window 142, FIGS. 3A and 3D show that the wall 117 of the fitting 100-1 is further configured with at least one access port 150. The port 150 is an opening in the body 101 and is located on a side of the optical window 142 that is away from the window member 48. As may be necessary for such access to the window 142 or the clamp 144, many ports 150 may be provided in the wall 117.
By reference to FIG. 4A it may be understood that in one embodiment of the fitting 100-1 with the embodiment 132-2 of the optical window assembly 132, the second clear optical aperture 116 is configured so that the second annular wall 117 is clear, e.g., unobstructed and open, from the low end 126 (that is adjacent to the window member 48) to the upper end 134 (spaced from the window member). For the other embodiment 132-2 of the optical window assembly 132, the second end 134 of the fitting 100 is further configured with a third sealing seat 152. The structure of the assembly 132-2 is similar to that of the assembly 132-1, and includes the seat 152 configured with a recess 154 to receive a second seal, such as an O-ring, 156. FIGS. 4A and 4B show the assembly 132-2 further configured with an optical window 158 received in (mounted on) the seat 152. The second seal 156 between the seat 152 and the optical window 158 prevents gas from leaking into and past the second clear optical aperture 116 into the first clear optical aperture 78, while allowing optical access through the second clear optical aperture 116 and through the first clear optical aperture 78 into the chamber 42. A clamp 160 may be used to hold the window 158 against the second seal 156 and the seat 152.
Because the second clear optical aperture 116 is open from the low end 126 to the upper end 134 of the fitting 100, plasma from the chamber 48 may flow through the first clear optical aperture 78 and into the second clear optical aperture 116. As described above concerning the first clear optical aperture 78, even though the shield 66-1, the shield 109, and other shield embodiments (described below) are configured to substantially reduce the strength of the electric field 62 that may extend across the fitting and the second clear optical aperture 116, the electric field 62 of some small strength may cross second clear optical aperture 116 and interact with the plasma. To protect the wall 117 from the effects of such low strength electric field 62, FIG. 4A also shows the annular wall 117 provided with protective layers, such as second coatings 162. Each of the coatings 162 has an inner coating diameter that is substantially the same as a value of the coating diameter D1 of the first clear optical aperture 78. The coatings 162 may be the same type as coating 82, and may be deposited on the wall 177, all as described above. Thus, about one-half inch at each end 134 and 126 of the wall 117 may be provided with the coatings 162. As noted above, without the coatings 162 an exemplary aluminum-containing ceramic will react with fluorine to form aluminum fluoride, which will form particles easily removed from the wall 80 during processing inside the chamber, such as by flaking off, which particles would enter the chamber 48. In the embodiment of the second clear optical aperture 116 having the coatings 162, e.g., of yttrium oxide that requires ion bombardment of high energy to be sputtered, in the second clear optical aperture 116 there is a low rate of aluminum fluoride formation adjacent to the coatings 162, which may have a combined one inch of the wall 117 protected from the effects of the low strength electric field 62 in the above exemplary configuration with D1 of 0.5 inch. In other words, one coating 162 may be a second Yttrium oxide coating on the second annular wall 117, and the second coating may extend from the first end 126 for a distance about equal to the diameter of the second annular wall 117. Also, the other coating may be a third Yttrium oxide coating on the second annular wall 117, and the second coating may extend from the second end 134 for a distance about equal to the diameter of the second annular wall 117.
FIGS. 3A and 4A show the fitting body 101-1 further configured with the second gas supply bore 118 extending parallel to the axis X, radially outward from the axis X and from the second clear optical aperture 116, but radially inward of the first bore 104. FIG. 3A shows the bore 118 configured with an angle section directed toward and intersecting the second clear optical aperture 116. The angle section avoids interference by the bore 118 with the first seal structure 120, for example. The second bore 118 may also be a single bore sized to supply process gas to the second clear optical aperture 116 and then to the first clear optical aperture 78 for distribution into the chamber 48.
For the embodiment of the optical window assembly 132-1 configured with the seat 136 adjacent to the first seal structure 120, the window 142 and the bores 104 and 118 are configured to avoid interference with each other. In this case, the bores 104 and 118 are oriented in the body 101 radially outside of the window 142, i.e., away from the axis X enough to extend vertically in the body 101-1 past and not intersect the window 142. Also, prior to assembly of the fitting 100-1 with the window member 48, the lower end 126 of the wall 117 of the fitting 101-1 may be provided with the coating 162, which may be the second coating 162 described above. The axial length of such second coating 162 may extend from the end 162 to the location of the seat 136.
Further, consistent with the above-described minimum length from the window 48 to the optical window 142 (as necessary to avoid the noted contamination and damage to the optical window 142), the optical window 142 may be at an axial location between the ends 126 and 134. That axial location may be selected according to the process to be performed in the chamber 42, for example, which may include the strength of the electric field 62. It may be understood that the process, for example, may be such as to make it necessary to locate the optical window 142 at a location at which the strength of the electric field is substantially reduced, to prevent sputtering of the optical window (which creates aluminum-containing contamination), and to prevent deposition onto the optical window. In that event, the embodiment 100-1 of the fitting may be provided with the embodiment 132-2 of the optical window, i.e., the optical window 158 as shown in FIG. 4A. Further, in the implementation of the embodiment 132-2 the fitting 100-1 may have an axial length from end 126 to end 134 of from about three to about six inches, and the shield 66-1 may have a corresponding axial length 52-2 above the window 48, for example. The optical window 158 may thus be located spaced from the window 48, where the strength of the electric field 62 is substantially reduced, so that there are minimal amounts of the above-described contamination and damage to the optical window 158. The end 134 with the optical window 158 is thus spaced from the first end 126 to locate the seat 154 (and thus the optical window 158) where the strength of the electric field is substantially reduced as compared to the electric field strength adjacent to the process chamber window 48. This optical window location may thus provide the above-described minimum length from the window 48 to the optical window 158.
FIG. 4A shows a gas inlet 180 that for the two bores 104 and 118, for example, is a dual gas inlet. The inlet 180 may be secured (as by suitable fasteners) to the fitting to align inlet bores with horizontal extensions of the bores 104 and 118. For embodiments of the present invention with a requirement for more than two gases, the inlet 180 may be configured with more inlet bores and the fitting configured with more bores of the type of bores 104 or 118, for example.
FIGS. 5A and 5B illustrate another embodiment 100-2 of the fitting 100 assembled to the window 48 shown in FIG. 2A. The fitting 100-2 is configured with the fitting functions and the functions of the shield 66 integral, or integrated into one piece, so that the fitting may be referred to as an integrated shield and gas supply unit, identified by reference number 100-2. Reference numbers used above that refer to similar structure are used below to describe the unit 100-2, and a “-2” is used to refer to structure unique to the unit 100-2. The integral shield aspects (similar to shield 66) are referred to as 66-2. The body 101-2 of the unit 100-2 is configured with the shield 66-2. The shield 66-2 is configured with a thin annular shield protrusion 190 at the first (lower) end 126. The groove 64 of the window 48 may receive the shield protrusion 190 for protecting the access region 52, and the protection is that described above in re FIG. 2A.
The unit 101-2 may be fabricated from material adapted to substantially block the electric field 62 from entering the access region 52. Such material, and other configuration of the unit 101-2 (i.e., the protrusion 190) promote an electric field-free condition within the unit. For the desired protection, above the protrusion 190 the unit 100-2 is configured as a solid cylinder member 68-2 configured to be received in the access region 52 and to provide the gas supply and optical access described above. FIG. 5A shows that with respect to embodiment 66-2, the protrusion 190 is received in the groove 64 to encompass section 52-1 of the access region. Also, the unit 100-2 is shown configured to extend in the direction of the X axis out of the groove 64 to encompass the axial section 52-2 (FIG. 2C) of the access region.
For clarity of illustration, FIG. 5A does not show the configuration shown in FIG. 3A of the plenum 74 and window 48 for assisting in alignment of the window 48 during assembly with embodiments of a multi-function fitting 100. However, in the manner shown in FIG. 3A, the unit 100-2 and window 48 may be configured with the first pin hole 102, and with the body 101 provided with the gas bore 104 configured to supply process gas to the plenum 74, with the second pin hole 106, and the alignment pin 108 to properly locate the fitting 100 relative to the window 48. The embodiment 66-2 of the shield 66 is thus received in the groove 64 to encompass section 52-1 of the access region, and the body 101 of the unit 100-2 extends in the direction of the X axis out of the groove 64 to encompass the axial section 52-2 of the access region. The pin 108 may be used to properly locate the fitting 100 relative to the window 48, and the shield 66-2 (via the protrusion 190) may also be located and placed in the groove 64. FIG. 5A shows the shield 66-2 with the protrusion 190 around the section 52-1 of the access region 52. FIG. 5A also shows that with the shield 66-2 received in the groove 64 encompassing section 52-1 of the access region, the body 101-2 extends in the direction of the X axis encompass the axial section 52-2 (FIG. 2A) of the access region. The body 101-2 is configured with a lower mount flange 200 configured to cooperate with the flat shield 109 and a fastener to secure the body 101-2 to the window member 48. The flange 200 and window 48 are pulled together by the fastener so that the fitting is pressed downwardly onto the window member 48 so that the vacuum is maintained by the same first seal structure 120, as described above.
As mounted and secured, the integral shield 66-2 is also in position to protect the access region 52 from the electric field 62. Also as mounted and secured, the unit 100-2 is in position to admit at least one gas to the window member 48 for injection into the process chamber 42, and to provide optical access through the first clear optical aperture 78 to the chamber. The unit 100-2 is thus also a multi-function fitting and shield received within the second section 52-2 of the access region 52 for protection from the electric field.
FIG. 5A shows an embodiment of the unit 100-2 in which the body 101-2 is configured with the second clear optical aperture 116 that may be the same as that used in FIG. 3A. The body 101-2 is further configured with the gas supply bore 104 extending parallel to the axis X and vertically aligned with the annular plenum 74, and with the bore 118 to supply gas to the second clear optical aperture 116. FIG. 5A shows the lower end 126 also configured with one embodiment 132-1 of the optical window assembly 132, as described above. FIG. 5B shows the body 101-2 configured so that the upper end 134 of the body 101-2 is configured with the other embodiment 132-2 of the optical window assembly 132, also as described above. Thus, the embodiment 100-1 of the fitting may be provided with the embodiment 132-2 of the optical window, i.e., the optical window 158 as shown in FIG. 4A. In the implementation of the embodiment 132-2 the fitting 100-1 may have an axial length from end 126 to end 134 as described above so that the optical window 158 is located where the strength of the electric field 62 is substantially reduced, which may result in minimal amounts of the above-described contamination and less damage to the optical window 158. Such optical window location may be from about three inches to about six inches from the window 48, for example. It may be understood that the second clear optical aperture 116 is thus configured so that the second annular wall 117 is clear, e.g., unobstructed and open, from the low end 126 (that is adjacent to the window member 48) to the upper end 134 (spaced from the window member), and is also provided with the coatings 162.
FIG. 5B shows the gas inlet 180 for the two bores 104 and 118, for example, to provide a dual gas inlet. The inlet 180 may be secured (as by suitable fasteners) to the fitting to align inlet bores with horizontal extensions of the bores 104 and 118. For embodiments of the present invention with a requirement for more than two gases, the inlet 180 may be configured with more inlet bores and the fitting with more bores of the type of bores 104 or 118, for example.
In review, embodiments of the present invention satisfy the described needs by providing further improvements in accessing processing chamber 42, where multiple access is provided by the window member 48 with the clear optical aperture 78 and with the dual supply gas bores 104 (feeding plenum 74) and 118 (for gas supply to aperture 78). This need is met, for example, by overcoming the conflicting requirements for the relatively large minimum diameter of the clear optical aperture 78 for the optical function and for a relatively small diameter of one or more gas bores 104 or 118 (or of the plenum 74) for gas supply to the chamber 42 to avoid plasma formation, for example. The conflicting requirements are overcome by the combination of protection of the dual gas supply bores 104 and 118 (and plenum 74) and the first clear optical aperture 78, protection being from the electric field 62 established by the coil 60 that surrounds the clear optical aperture 78. In the embodiments, the shield 66 is configured to extend into the window 48 to provide such protection for the first section 52-1 of the clear optical aperture 78. The remaining second section 52-2 of the clear optical aperture 78 may be provided with the protective coating 82 to provide such protection from the reduced-strength electric field 62.
The protective coating 82 (such as yttrium oxide) provided on the annular wall 80 of the clear optical aperture 78 is facilitated by the inner coating diameter D1 substantially the same as the value of the axial length L of the clear optical aperture. Because the exemplary 0.5 inch minimum diameter D1 of the clear optical aperture 78 is also a value of an acceptable thickness L of the window 48, and because both the diameter D1 and length L are also acceptable for applying the coating 82 to the entire surface of the wall 80 (e.g., by the torch plasma process), the thickness of the window 48 may be reduced to the value of L, the requirements of the minimum diameter of the clear optical aperture 78 may be met, and the dual shielding and coating protection of the first clear optical aperture 78 is facilitated.
In addition, for providing optical access for exemplary spectroscopic observation of chamber processes, embodiments of the present invention described with respect to FIGS. 4A and 5B enable location of the optical window 158 where the strength of the electric field 62 is substantially reduced, which may result in minimal amounts of the above-described contamination and less damage to the optical window 158, and allow provision of the minimum diameter of the clear optical aperture 78 of the exemplary one-half inch.
Further, for situations (e.g., process) that permit the optical window 142 (FIGS. 3A and 5A) to be located nearer to the end 126, this location is within both embodiments 66-1 and 66-2 of the shield 66, such that the optical window 142 is protected by these shields 66 and the wall 117 is protected by the coating 162 (shown in FIGS. 4A and 5B) as described above.
Although the foregoing invention has been described in some detail for purposes of clarity of understanding, it will be apparent that certain changes and modifications may be practiced within the scope of the appended claims. For example and not limitation, while the shield 66 has been described as being cylindrical, the shield 66 may be configured with other three-dimensional shapes. Exemplary shield cross-sectional configurations include square and oval.
Accordingly, the present embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalents of the appended claims.

Claims

1. A window for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window, the window comprising:

a window member configured with outer and chamber sides and a groove extending from the outer side into the member parallel to the axis, the groove defining a first section of the access region to be protected from the electric field, the window member being further configured with a clear optical aperture having an annular wall configured with an axial length between the outer side and the chamber side, the clear optical aperture being partly surrounded by the groove, the clear optical aperture being further configured with a diameter; and

a coating on the annular wall of the clear optical aperture, the annular wall with the coating having an inner coating diameter that is substantially the same as a value of the axial length of the clear optical aperture, the material from which the coating is fabricated being taken from the group consisting of cerium oxide, zirconium oxide, yttria-stabilized zirconia, thermally-sprayed aluminum oxide, yttrium oxide, and yttrium oxide having pores, wherein the pores are sealed with a material taken from the group consisting of methacylate ester and polymer.

2. A process chamber window as recited in claim 1, wherein the window member is further configured from one piece of ceramic.

3. A process chamber window as recited in claim 1, wherein the window member is further configured with an annular gas plenum and a plurality of nozzles, each of the nozzles being connected to the annular gas plenum.

4. A process chamber window as recited in claim 1, wherein the chamber side of the window member is configured with a flat surface.

5. A process chamber window as recited in claim 3, wherein the chamber side of the window member is configured with a projection defined by an axially-extending surface and a flat surface parallel to the chamber side, the nozzles intersecting the axially-extending surface.

6. A multi-function process chamber window assembly for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window, for admitting at least one gas to the process chamber, and for providing optical access to the chamber, the assembly comprising:

a three-dimensional shield having a length extending parallel to an access region axis and being fabricated from material adapted to substantially block the electric field;

a window member configured with respect to the access region axis, the member being configured with outer and chamber sides and a groove extending from the outer side into the member, the groove extending parallel to the axis, the groove defining a first section of the access region to be protected from the electric field, the groove being configured to receive a portion of the shield to protect the first section of the access region from the electric field, the groove receiving the portion of the shield so that the shield extends out of the groove and away from the outer side so that a second section of the access region is defined within the shield, the shield protecting the second section from the electric field, the window member being further configured with a first clear optical aperture defined by a first annular wall extending co-axially with the axis and configured with an axial length between the outer side and the chamber side, the first clear optical aperture being partly surrounded by the groove, the first clear optical aperture being further configured with a diameter for clear optical access; and

a first coating on the first annular wall, the first annular wall with the coating having an inner coating diameter that is substantially the same as a value of the axial length of the first clear optical aperture, the coating protecting the first clear optical aperture from effects of the electric field so that the protection extends past the shield in the groove to the chamber side of the window member, the material from which the first coating is fabricated being taken from the group consisting of cerium oxide, zirconium oxide, yttria-stabilized zirconia, thermally-sprayed aluminum oxide, yttrium oxide, and yttrium oxide having pores, wherein the pores are sealed with a material taken from the group consisting of methacylate ester and polymer.

7. An assembly as recited in claim 6, the assembly further comprising:

a multi-function fitting received within the second section of the access region defined by the shield for protection from the electric field, the fitting being configured with a second clear optical aperture having a second annular wall extending co-axially with the axis and aligned with the coated first clear optical aperture to supply gas to the first clear optical aperture and allow clear optical access to the chamber through the first and second clear optical apertures.

8. An assembly as recited in claim 7, wherein:

the window member is configured with a plenum extending from the outer side into the member and with a plurality of nozzles extending from the plenum to the chamber side to supply gas to the chamber; and

the fitting is further configured with a gas supply bore extending parallel to the axis and aligned with the plenum.

9. An assembly as recited in claim 8, the assembly further comprising a seal structure between the fitting and the window member.

10. An assembly as recited in claim 9, wherein:

the shield is configured with opposite ends, each of the ends being configured with a coupler, one coupler securing the shield to the window member with the shield in the groove, the other coupler securing the fitting to the shield so that the fitting is urged toward the window member; and

the seal structure is configured so that in response to the other coupler urging the fitting toward the window member the seal structure seals to the window member so that gas flows from the gas supply bore into the plenum separately from the first and second clear optical apertures and gas flows from the second clear optical aperture into the first clear optical aperture separately from the gas supply bore and the plenum.

11. An assembly as recited in claim 7, wherein the fitting is configured with an end, the assembly further comprising:

a first seal structure between the end of the fitting and the window member; and

wherein the end is configured with a seat adjacent to the seal structure and co-axial with the access region axis;

the assembly further comprising an optical window received in the seat and a second seal structure between the seat and the optical window to prevent gas from leaking past the second optical aperture while allowing optical access through the second clear optical aperture and the first clear optical aperture into the chamber.

12. An assembly as recited in claim 11, wherein the fitting is further configured with at least one access port in the second annular wall to provide access to the optical window, the port being located on a side of the optical window that is away from the window member.

13. An assembly as recited in claim 7, wherein the second clear optical aperture is configured so that the second annular wall is open from a first end that is adjacent to the window member to a second end spaced from the window member, the second end of the fitting being further configured with a sealing seat, the assembly further comprising:

the assembly further comprising an optical window received in the sealing seat and a second seal structure between the seat and the optical window to prevent gas from leaking past the second optical aperture while allowing optical access through the second clear optical aperture and the first clear optical aperture into the chamber;

the spacing of the second end from the window member enabling location of the optical window where the strength of the electric field is substantially reduced as compared to the electric field strength adjacent to the process chamber window.

14. An assembly as recited in claim 13, the assembly further comprising:

a second coating on the second annular wall, the second coating extending from the first end for a distance about equal to the diameter of the second annular wall; and

a third coating on the second annular wall, the second coating extending from the second end for a distance about equal to the diameter of the second annular wall;

the second and third coatings being fabricated from the same material as the first coating.

15. An assembly as recited in claim 6, wherein:

the window member is configured with an annular plenum extending from the outer side into the member and with a plurality of nozzles extending from the annular plenum to the chamber side to supply gas to the chamber;

the assembly further comprises a multi-function fitting received within the second section of the access region defined by the shield for protection from the electric field, the fitting being configured with a second clear optical aperture having a second annular wall extending co-axially with the axis and aligned with the coated first clear optical aperture to supply gas to the first clear optical aperture and allow clear optical access to the chamber through the first and second clear optical apertures, the fitting is further configured with a gas supply bore extending parallel to the axis and aligned with the annular plenum;

the shield is configured with opposite ends, each of the ends being configured with a coupler, one coupler securing the shield to the window member with the shield in the groove, the other coupler securing the fitting to the shield so that the fitting is urged toward the window member, the end configured with the one coupler being configured with a seat that is co-axial with the access region axis; and

the assembly further comprises a first seal structure between the window member and the one end of the fitting that is configured with the one coupler, the first seal structure sealing the gas supply bore to the plenum, an optical window received in the seat, a second seal structure between the seat and the optical window to prevent gas from leaking past the second optical aperture while allowing optical access through the second clear optical aperture and the first clear optical aperture into the chamber.

16. An assembly as recited in claim 15, wherein:

the fitting is further configured with a second gas supply bore extending relative to the axis to supply gas to the first clear optical aperture;

the first seal structure seals the second gas supply bore to the first clear optical aperture when the fitting is urged toward the window member while allowing the optical access through the second clear optical aperture and the first clear optical aperture into the chamber.

17. A multi-function process chamber window assembly for protecting an access region for access to a process chamber from an electric field generated adjacent to the process chamber window while providing at least two gas inlets to the process chamber and allowing optical access to the chamber, the assembly comprising:

an integrated shield and gas supply unit for protecting the access region from the electric field, the unit having a thin three-dimensional protrusion at a first end and being configured with a body that is thicker than the protrusion, the body being further configured to extend from the first end parallel to an access region axis to a second end, the body being further configured with a first annular wall defining a unit clear aperture extending along the axis from the first end to the second end, the body being further configured with a first gas supply bore extending parallel to the axis and intersecting the unit clear optical aperture adjacent to the first end, the body being further configured with a first coupler, the unit being fabricated from material adapted to substantially block the electric field so that the unit clear optical aperture is protected from the electric field;

a window member configured with respect to the access region axis, the member being configured with outer and chamber sides and a groove extending from the outer side into the member, the groove extending parallel to the axis, the groove being configured to receive the thin protrusion to protect a first section of the access region from the electric field, the member being further configured with a second coupler configured to cooperate with the first coupler to hold the protrusion in the groove with the unit extending away from the outer side of the member so that a second section of the access region is defined by and is protected by the body from the electric field, the window member being further configured with a window member clear optical aperture having a second annular wall extending co-axially with the axis and configured with an axial length between the outer side and the chamber side, the window member clear optical aperture being partly surrounded by the thin protrusion received in the groove, the window member clear optical aperture being further configured with a diameter; and

a coating on the second annular wall, the second annular wall with the coating having an inner coating diameter that is substantially the same as a value of the axial length of the window member clear optical aperture, the coating protecting the window member clear optical aperture from the electric field, the material from which the coating is fabricated being taken from the group consisting of cerium oxide, zirconium oxide, yttria-stabilized zirconia, thermally-sprayed aluminum oxide, yttrium oxide, and yttrium oxide having pores, wherein the pores are sealed with a material taken from the group consisting of methacylate ester and polymer.

18. An assembly as recited in claim 17, wherein:

the body of the unit is further configured with a second gas supply bore extending parallel to the axis and to the first end; and

the window member is further configured with a plenum extending from the outer side into the member, plenum receiving gas from the second gas supply bore, the window member being configured with a plurality of nozzles that are spaced around the axis and receive the gas from the plenum.

19. An assembly as recited in claim 17, wherein:

the body of the unit is further configured with a pair of co-axial annular recesses, a first of the recesses is between the unit clear optical aperture and the second gas supply bore, a second of the recesses is between the second gas supply bore and the annular groove;

the assembly further comprises a seal member received in each of the recesses in opposition to the outer side of the window member; and

with the couplers holding the protrusion in the groove the outer side of the window member is held opposed to the seal members in the recesses to seal the second gas supply bore to the plenum and seal the unit clear optical aperture to the window member clear optical aperture while allowing optical access through the unit clear optical aperture and the window member clear optical aperture into the chamber.

20. An assembly as recited in claim 17, wherein:

the second end of the body of the integrated unit is further configured with a seat;

the assembly further comprises an optical window configured for reception in the seat and a clamp for holding the optical window in the seat; and

the second end is spaced from the first end to locate the seat for the optical window where a strength of the electric field is substantially reduced as compared to an electric field strength adjacent to the process chamber window.