US20090038985A1

US20090038985A1 - Photomask pod, photomask transport pod and supporter thereof

Info

Publication number: US20090038985A1
Application number: US12/110,276
Authority: US
Inventors: Chien-Feng Wang
Original assignee: Gudeng Precision Industrial Co Ltd
Current assignee: Gudeng Precision Industrial Co Ltd
Priority date: 2007-08-10
Filing date: 2008-04-25
Publication date: 2009-02-12
Also published as: TWM331743U

Abstract

A photomask pod and a photomask transport pod are provided for preventing particles in the environment from defiling a photomask as well as charge accumulation on the photomask from causing ESD damage. The photomask pod comprises two covers and the supporters or retainers on at least one of the two covers are made of a static dissipative material, which facilitates reducing charge accumulation and protecting the photomask from ESD damage.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates to photomask pods and photomask transport pods and, more particularly, to a photomask pod and a photomask transport pod which can prevent damage caused by ESD.
2. Description of the Related Art
In the rapidly developing semiconductor technology, optical lithography plays an important role and wherever pattern definition is conducted, optical lithography is requisite. As to the application of optical lithography relating to semiconductors, a designed circuit pattern is used to produce a light-transparent photomask. Based on the principle of exposure, after a light passes through the photomask to be projected on a silicon wafer, the circuit pattern formed on the photomask can be exposed onto the silicon wafer. Since any dust (such as particles, powders or an organic material) can adversely affect the quality of such projected pattern, the photomask used to produce the pattern on the silicon wafers is required with absolute cleanness. Thus, clean rooms are typically employed in general wafer processes for preventing particles in the air from defiling photomasks and wafers. However, absolute dustless environment is inaccessible even in known clean rooms. Hence, reticle pods that facilitate preventing defilement are implemented in current semiconductor processes for the purpose of storage and transportation of photomasks so as to ensure cleanness of the photomasks.
Conventional photomask pods are generally made of macromolecular materials, which possess the advantages of easy forming, inexpensiveness and the ability to form transparency. Such macromolecular materials, which are insulating and have high surface resistivity, are liable to induce static due to friction and separation. Especially, in the low-moisture environment of a clean room, photomask pods made of such macromolecular materials are apt to produce and accumulate charges thereon. Additionally, when a photomask is placed in or taken out from a photomask pod, static may easily occur on the surface of the photomask owing to friction. Static on the photomask is attractive to particles in the air and may, even worse, cause electrostatic discharge (ESD) on metal wires of the photomask. Transient currents induced by ESD can bring sparks or arcs that come along with powerful currents and high heat. As such powerful currents and high heat oxidize and melt the metal wires of the photomask, the pattern on the photomask is consequently deformed.
Many solutions have been introduced to eliminate ESD. The primary solution is to manage the operational environment with proper atmospheric moisture. Clothes having grounding effects for staff and ion fans may be also helpful to eliminate environmental static. However, there are countless factors in the operational environment, and it is actually impossible to completely protect photomasks from being damaged by static.
An alternative solution is to change the material of the components composing a photomask pod, as disclosed in U.S. Pat. No. 6,513,654, wherein a supporter having a grounding effect is provided so that when the photomask pod contacts a corresponding station, the supporter helps to conduct out charges on the photomask. Furthermore, another solution, provided by U.S. Pat. No. 6,247,599, involves equipping a metal layer on a bottom plate, a cover, or a handle of the photomask pod so as to reduce charge accumulation. While all the aforementioned solutions are dependent on grounded electrically conductive components to release charges, it is to be noted that when static is released by such electrically conductive components, currents are unavoidably generated and discharge can still occur to damage the photomask.
Therefore, the present invention provides novel supporters or retainers to remedy the above defects of the prior arts.

SUMMARY OF THE INVENTION

To overcome the aforementioned defects of the prior arts, the present invention provides a photomask pod which has supporters or retainers made of a particular material. In the present invention, the supporters or retainers are made of a static dissipative material so that even when charges are generated on the static dissipative material because of friction, an adjacent metal material can instantly conduct out the charges so as to eliminate charge accumulation and ESD.
It is one objective of the present invention to provide a supporter of a mask, which is made of a static dissipative material to reduce charge accumulation and to protect a photomask from being damaged by static.
It is another objective of the present invention to provide a supporter of a photomask, which is made of a static dissipative material to continuously conduct out charges so as to protect a photomask from being damaged by high heat resulted from transient discharge.
It is another objective of the present invention to provide a retainer of photomask, which is made of a static dissipative material to reduce charge accumulation and to protect a photomask from being damaged by static.
It is another objective of the present invention to provide a retainer of a photomask, which is made of a static dissipative material to continuously conduct out charges so as to protect a photomask from being damaged by high heat resulted from transient discharge.
The present invention discloses a photomask pod and a photomask transport pod with supporters and retainers which directly contact a photomask and are made of a static dissipative material so as to provide a way for dissipating static. The static dissipative material has a property between conductive and non-conductive. Since the static dissipative material features a slow conductive velocity, discharge is not liable to happen between the supporters or the retainers and the photomask or the photomask pod. Consequently, the photomask can be free from the influence of heat generated by discharge so that the present invention provides superior protection to the photomask while shielding is also presented. As a result, the photomask is protected from the risk of being damaged.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein

FIG. 1 is a schematic view of a photomask pod;

FIG. 2 illustrates a supporter and a retainer of the present invention according to one preferred embodiment;

FIG. 3A to FIG. 3D illustrate a supporter of the present invention according to one preferred embodiment;

FIG. 4 illustrates the supporter of the present invention;

FIG. 5A and FIG. 5B illustrate a supporter of the present invention according to another preferred embodiment;

FIG. 6 illustrates a supporter of the present invention according to another preferable embodiment, and

FIG. 7 illustrates a supporter and a retainer of the present invention according to another preferred embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

It is to be stated at first that essential components and combining means among the components of the disclosed supporters and retainers made of a static dissipative material in the present invention are well known in the art and need not be discussed at length herein. Meanwhile, the basic structure of photomasks pod and the principle where photomask pods are based on are also well known by those skilled in the art and need not be disclosed in the present invention. Beside, the accompanying drawings are provided for illustration and are not and need not to be drawn in scale.
FIG. 1 is provided for illustrating a photomask pod or a photomask transport pod. Therein, the photomask pod or photomask transport pod 100 comprises a first cover or a top cover 102 and a second cover or a bottom plate 104. The first cover or top cover 102 and the second cover or bottom plate 104 can be assembled to enclose an inner space for accommodating a photomask 114 therein. The first cover 102 or the second cover 104 of the photomask pod or photomask transport pod 100 may be made of metal. Alternatively, a metal liner may be additionally equipped in the photomask pod or photomask transport pod 100 to provide the shielding effect so as to insulate an extrinsic interference. The second cover or bottom plate 104 is composed of a body 106, a conductive panel 108, a plurality of supporters 112 and a plurality of retainers 110. The conductive panel 108 is arranged on a surface of the body 106 facing the inner space and is made of a conductive material. The plural retainers 110 and supporters 112 are settled on the conductive panel 108 while the retainers 110 and supporters 112 may be made of different materials or made of an identical material. The supporters 112 are electrically connected to the conductive panel 108 and are made of a static dissipative material having a surface resistivity ranging from about 10⁴to about 10¹¹Ω. When the photomask 114 is placed on the supporters 112, the supporters 112 directly contact the photomask 114. The static dissipative material helps to continuously conduct out charges so as to protect the photomask from being damaged by high heat resulted from transient discharge. Since the charge accumulation of the photomask is reduced, the photomask is protected from being damaged by static.
FIG. 2 provides a preferable embodiment of the present invention, showing a plurality of supporters or retainers deposited in a photomask pod. A second cover 104 of the photomask pod 100 comprises of a body 106, a conductive panel 108, a photo mask 114, a plurality of retainers 110 and a plurality of supporters 112. The first cover 102 or the second cover 104 of the photomask pod 100 may be made of metal. Alternatively, a metal liner may be additionally equipped in the photomask pod or photomask transport pod 100 to provide the shielding effect so as to insulate an extrinsic interference. The conductive panel 108 is settled on the body 106 while the plural retainers 110 or supporters 112 are provided on the conductive panel 108. Therein, the retainers 110 and supporters 112 are formed by multi-component injection molding and then combined mutually. The supporters 112 are provided as inserting pieces and are made of a static dissipative material having a surface resistivity ranging from about 10⁴to about 10¹¹Ω. When being placed in the second cover 104 of the photomask pod 100, the photomask 114 is supported by a retainer 110 as well as the plural supporters 112 and is retained on the second cover 104 by the retainers 110. The retainers 110 surrounding the photomask 114 function to reduce possible vibrations occurred in transportation of the photomask pod 100 and for securing the photomask 114 from impact. Hence, the plural retainers 110 and the plural supporters 112 are provided to function collaboratively.
FIG. 3A provides another preferred embodiment of the plural supporters in the photomask pod. Therein, a supporter 200 is integrally formed and made of a static dissipative material having a surface resistivity ranging from about 10⁴to about 10¹¹Ω. The supporter 200 comprises at least one planar base 202 connecting with a first inclined surface 204 that is further connected with a second inclined surface 206 so that the planar base 202, the first inclined surface 204 and second inclined surface 206 are formed as the supporter 200 integrally. It is to be stated that the configuration of the first inclined surface 204 and the second inclined surface 206 is not to be limited by the present invention. Therein, the first inclined surface 204 is approximately perpendicular to the planar base 202. However, the degree of the angle between the first inclined surface 204 and the planar base 202 may vary in alternative embodiments. Another angle is also formed by the second inclined surface 206 and the first inclined surface 204 to provide a surface for smoothly guiding an article to slide on the second inclined surface 206. Furthermore, two first openings 208 are provided near both lateral sides of the supporter 200. Each of the first openings 208 is equipped with an upper fastening piece 210 and a lower fastening piece 212. Thereby, when a photomask 114 is placed in the bottom plate 104 of the photomask transport pod 100 and then the top cover 102 is assembled to the bottom plate 104, the second inclined surfaces 206 of the supporters 200 helps the photomask 114 to be guided smoothly to a proper position in the photomask transport pod 100 where the photomask 114 can be steadily positioned. Then the upper fastening pieces 210 and the lower fastening pieces 212 help to support and fix the photomask 114.
In addition, FIG. 3A, FIGS. 3B, 3C and 3D provide one embodiment of the supporters arranged in the photomask transport pod. The embodiment shown in FIG. 3B is featured by a second opening 214 additionally formed at a central portion of the supporter 200. In different embodiments, this second opening 214 may be set at the central portion of the supporter 200 or alternatively formed on the second inclined surface 206 with a plurality of openings. This design of the second opening 214 diminishes a contact area between the photomask 114 and the supporter 200 so as to reduce the generation of dust and particles. FIG. 3C and FIG. 3D both represent another embodiment of the supporter 200 of the present invention. The supporter 200 of the present embodiment is characterized in that at least one guiding track 216 is arranged near the central portion. Alternatively, two guiding tracks 216 may be provided at two sides of said second opening 214. On objective of the guiding track 216 is to further diminish the contact area between the photomask 114 and the supporter 200 when the photomask 114 contacts and slides on the supporter 200 so as to increase the yield of the manufacturing process. Besides, for fixing the supporter 200 in the top cover 102 of the photomask transport pod 100, a pair of connecting components 218 may be additionally provided at two peripheral portions of a lower surface of the planar base 202 of the supporter 200, as shown in FIG. 4. Thereby, the supporter 200 can be fixed at a side of the top cover 102. The supporter 200 may be made of a static dissipative material with a surface resistivity ranging from about 10⁴to about 10¹¹Ω or made of an elastic material. The static dissipative material is polyetheretherketone.
FIGS. 5A, 5B and 6 provide one more embodiment of the plural supporters in the photomask pod. Therein, a supporter 300 comprises a base 302 and one or plural supporting points 304 arranged on the base 302 so that the base 302 can be fixed at each corner of the top cover 102 of the photomask transport pod 100. At the meantime, a flexible bent component 306 is connected to the base 302, wherein the flexible bent component 306 has one end integrally extending from the base 302 and has an opposing end flexibly suspending upon this or the plural supporting points 304. The flexible bent component 306 further comprises a pressing surface 308 and a propping surface 310 so that when the top cover 102 and bottom plate 104 of the photomask transport pod 100 enclose the photomask 114, the pressing surface 308 and the propping surface 310 of the flexible bent component 306 can contact and fix the photomask 114. Additionally, this or the plural supporting points 304 may be configured on the supporter 300 obliquely with an included angle between each said supporting point 304 and the supporter 300. The included angle may vary in different embodiments. In the present embodiment, the plural supporting points 304 are employed for example. Moreover, the supporter 300 is made of a static dissipative material with a surface resistivity ranging from about 10⁴to about 10¹¹Ω and is detachably connected to the top cover 102 of the photomask transport pod 100. The static dissipative material is polyetheretherketone.
FIG. 7 illustrates one more embodiment of the plural retainers or supporters provided in the photomask pod. Therein, a photomask pod 100 comprises a first cover 102 and a second cover 104, which can be assembled to enclose an inner space to accommodate a photomask 114. The first cover 102 or the second cover 104 of the photomask pod or photomask transport pod 100 may be made of metal. Alternatively, a metal liner may be additionally equipped in the photomask pod or photomask transport pod 100 to provide the shielding effect so as to insulate an extrinsic interference. A plurality of supporters 112 in the photomask pod 100 may be provided in both the forms of the first supporter 112 and the third supporter 300. The first supporter 112 are arranged on the second cover 104 and the third supporter 300 are deposited on the first cover 102. A conductive panel 108 is arranged on a body 106 of the second cover 104 and the plural retainers 110 or the first supporter 112 are positioned on the conductive panel 108, wherein the first supporter 112 are electrically connected to the conductive panel 108. The retainers 110 and the first supporter 112 may be made of different materials or made of an identical material. Therein, the retainers 110 and the first supporter 112 are formed by multi-component injection molding method and then combined mutually. The first supporter 112 is provided as inserting pieces and is made of a static dissipative material having a surface resistivity ranging from about 10⁴to about 10¹¹Ω. The third supporter 300 comprises a base 302 and one or plural supporting points 304 arranged thereon so that the base 302 can be fixed at each corner of the top cover 102 of the photomask pod 100. Meanwhile, a flexible bent component 306 is connected to the base 302, wherein the flexible bent component 306 has one end integrally extending from the base 302 and has an opposing end suspending upon the one or plural supporting points 304. Thereby, when placed in the second cover 104 of the photomask pod 100, the photomask 114 is supported by the plural retainers 110 and the first supporter 112 and is fixed on the second cover 104 by the retainers 110. The retainers 110 surrounding the photomask 114 function to reduce possible vibrations occurred in transportation of the photomask pod 100 and to secure the photomask 114 to prevent impact. Hence, the retainers 110 and the first supporter 112 are provided to function collaboratively. When the first cover 102 and the second cover 104 enclose the photomask 114, a flexible bent component 306 of the third supporter 300 on the first cover 102 further comprises a pressing surface 308 and a propping surface 310 so that the pressing surface 308 and the propping surface 310 of the flexible bent component 306 can contact the photomask 114 to fix it and jointly support the photomask 114. Besides, since the photomask 114 directly contacts with the first supporters 112 and third supporter 300, to use the static dissipative material with a surface resistivity ranging from about 10⁴to about 10¹¹Ω as the material of the supporters can continuously conduct out charges so as to protect a photomask from being damaged by high heat resulted from transient discharge and to reduce charge accumulation and protect a photomask 114 from being damaged by static.
One additional embodiment of the present invention is herein provided for illustrating the plural retainers or supporters settled in the photomask transport pod 100. Therein, a photomask transport pod 100 comprises a top cover 102 and a bottom plate 104, which can be assembled to enclose an inner space to accommodate a photomask 114. The photomask transport pod 100 may be made of metal. Alternatively, a metal liner may be settled in the photomask transport pod 100 to provide the shielding effect so as to insulate an extrinsic interference. A plurality of supporters 112 in the photomask pod 100 may be provided in the forms of the first supporter 112, the second supporter 200 and the third supporter 300. The first supporters 112 are arranged on the bottom plate 104 and the second supporters 200 as well as the third supporters 300 are deposited on the top cover 102. At four corners of the top cover 102, the plural second supporters 200 or the third supporters 300 are provided and are detachably fastened to the corners of the top cover 102 by the connecting components 218 or the one or plural supporting points 304 of the base 302 thereof. The supporters 300 may be further equipped with a plurality of pressing surfaces 308 and propping surfaces 310 to fix and support the photomask 114. When placed in the bottom plate 104 of the photomask transport pod 100, the photomask 114 is supported by the plural retainers 110 as well as the first supporters 112 and is retained on the bottom plate 104 by the retainers 110. When the top cover 102 is assembled to the bottom plate 104, since the second supporters 200 are provided at the opening of a reversed-U shaped structure of the top cover 102 facing the bottom plate 104, the second inclined surfaces 206 of the second supporters 200 helps the photomask 114 to be smoothly guided into the position of the reversed-U shaped structure. Meanwhile, because the third supporter 300 are provided at the corners of the top cover 102, after being guided by the second inclined surfaces 206 of the second supporters 200 to the proper position, the photomask 114 is further jointly supported and fixed by the upper and lower fastening pieces 210 and 212 of the second supporters 200 and the pressing and propping surfaces 308 and 310 on the flexible bent component 306 of the plural third supporters 300. Besides, since the photomask 114 directly contact with the first, the second and the third supporters 112, 200 and 300, the static dissipative material of these supporters with the surface resistivity ranging from about 10⁴to about 10¹¹Ω helps to continuously conduct out charges so as to protect the photomask from being damaged by high heat resulted from transient discharge. Since charge accumulation is reduced, the photomask is protected from being damaged by static.
All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.
From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention, and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the scope of the following claims.

Claims

1. A photomask pod comprising:

a first cover, and

a second cover, which is assembled to the first cover so as to enclose an inner space for accommodating at lease one photomask;

wherein at least one of the first and second covers has a body with a plurality of supporters or retainers at a surface facing the inner space, in which the supporters or retainers are made of a static dissipative material.

2. The photomask pod of claim 1 wherein the static dissipative material has a surface resistivity ranging from about 10⁴to about 10¹¹Ω.

3. The photomask pod of claim 1 wherein the supporters and retainers are made of different materials.

4. The photomask pod of claim 1 wherein the supporters and retainers are made of an identical material.

5. The photomask pod of claim 1 wherein a conductive panel is provided at the surface of the body facing the inner space, and the supporters are deposited on the conductive panel and electrically connect with the conductive panel.

6. The photomask pod of claim 1 wherein the first cover or the second cover is made of metal.

7. The photomask pod of claim 1 wherein each of the supporters comprises:

a planar base connecting with a first inclined surface that further connects with a second inclined surface so that the planar base, the first inclined surface and the second inclined surface form as the supporter integrally, and two first openings are provided near both lateral sides of the supporter wherein each of the first openings is equipped with an upper fastening piece and a lower fastening piece.

8. The photomask pod of claim 1 wherein each of the supporters comprises:

a base, which affixes to each corners of the upper cover of the photomask pod via a plurality of supporting points, and

a flexible bent component, having one end which connects to the base and has an opposing end flexibly suspending between the plurality of supporting points, which further comprises a propping surface and a pressing surface;

wherein when the photomask pod encloses a photomask, the propping surface and the pressing surface of the flexible bent component contact the photomask so as to fix it.

9. The photomask pod of claim 1 wherein the photomask pod can also be a photomask transport pod.

10. A photomask pod comprising:

a first cover,

a second cover, which is assembled to the first cover so as to enclose an inner space for accommodating at least one photomask and at least one of the first and second covers has a body,

a plurality of retainers, which is provided at a surface of the body facing the inner space, and

a plurality of supporters, which is provided at the surface of the body facing the inner space and made of a static dissipative material;

wherein the plurality of retainers and the plurality of supporters are formed by multi-component injection molding method and then combined mutually.

11. The photomask pod of claim 10 wherein the static dissipative material has a surface resistivity ranging from about 10⁴to about 10¹¹Ω.

12. The photomask pod of claim 10 wherein the photomask pod can also be a photomask transport pod.

13. A supporter comprising:

a planar base connecting with a first inclined surface that further connects with a second inclined surface so that the planar base, the first inclined surface, and second inclined surface form as the supporter integrally, and two first openings are provided near both lateral sides of the supporter and each of the first openings is equipped with an upper fastening piece and a lower fastening piece wherein the supporter is partially or entirely made of a static dissipative material.

14. The supporter of claim 13 wherein the static dissipative material has a surface resistivity ranging from about 10⁴to about 10¹¹Ω.

15. The supporter of claim 14 wherein the static dissipative material is polyetheretherketone.

16. A supporter comprising:

a base, which affixes to each corner of an upper cover of a photomask pod via a plurality of supporting points, and

a flexible bent component, which has one end connecting to the base and an opposing end flexibly suspending upon the plurality of supporting points, which further comprises a propping surface and a pressing surface;

wherein when the photomask transport pod encloses a photomask, the propping surface and the pressing surface of the flexible bent component contact the photomask so as to fix it, in which the supporter is partially or entirely made of a static dissipative material.

17. The supporter of claim 16 wherein the static dissipative material has a surface resistivity ranging from about 10⁴to about 10¹¹Ω.

18. The supporter of claim 17 wherein the static dissipative material is polyetheretherketone.