CA1088218A - Ion implantation apparatus with a cooled structure controlling the surface potential of a target surface - Google Patents
Ion implantation apparatus with a cooled structure controlling the surface potential of a target surfaceInfo
- Publication number
- CA1088218A CA1088218A CA299,581A CA299581A CA1088218A CA 1088218 A CA1088218 A CA 1088218A CA 299581 A CA299581 A CA 299581A CA 1088218 A CA1088218 A CA 1088218A
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- CA
- Canada
- Prior art keywords
- target
- source
- electrons
- current
- walls
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/244—Detectors; Associated components or circuits therefor
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/02—Details
- H01J37/026—Means for avoiding or neutralising unwanted electrical charges on tube components
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/244—Detection characterized by the detecting means
- H01J2237/24405—Faraday cages
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/245—Detection characterised by the variable being measured
- H01J2237/24507—Intensity, dose or other characteristics of particle beams or electromagnetic radiation
Abstract
ION IMPLANTATION APPARATUS WITH A
COOLED STRUCTURE CONTROLLING
THE SURFACE POTENTIAL OF A TARGET SURFACE
Abstract of the Disclosure In an ion beam apparatus a structure for controlling the surface potential of the target comprising an electron source adjacent to the beam for providing electrons to the beam and means between the target and source for inhibit-ing rectilinear radiations, i.e., electron and other parti-cle and photon radiations between said source and said tar-get. This prevents heating of the target by the electron source and cross-contamination between the source and the target. The apparatus further includes means for maintain-ing said shield means at a lower temperature than said tar-get. A further structure is provided for the measurement of the ion beam current while controlling said surface poten-tial of the target which includes: walls adjacent to and electrically insulated from the target and surrounding the beam whereby the walls and target provide a Faraday Cage, means for introducing variable quantities of electrons into the beam within the Faraday Cage, means for measuring the target current, means for combining and measuring the target and wall currents to provide said ion beam current measurement and means for varying the quantities of intro-duced electrons to control the target current and thereby the target surface potential. Likewise, this apparatus further includes means for maintaining said shielding means at a temperature lower than said target.
COOLED STRUCTURE CONTROLLING
THE SURFACE POTENTIAL OF A TARGET SURFACE
Abstract of the Disclosure In an ion beam apparatus a structure for controlling the surface potential of the target comprising an electron source adjacent to the beam for providing electrons to the beam and means between the target and source for inhibit-ing rectilinear radiations, i.e., electron and other parti-cle and photon radiations between said source and said tar-get. This prevents heating of the target by the electron source and cross-contamination between the source and the target. The apparatus further includes means for maintain-ing said shield means at a lower temperature than said tar-get. A further structure is provided for the measurement of the ion beam current while controlling said surface poten-tial of the target which includes: walls adjacent to and electrically insulated from the target and surrounding the beam whereby the walls and target provide a Faraday Cage, means for introducing variable quantities of electrons into the beam within the Faraday Cage, means for measuring the target current, means for combining and measuring the target and wall currents to provide said ion beam current measurement and means for varying the quantities of intro-duced electrons to control the target current and thereby the target surface potential. Likewise, this apparatus further includes means for maintaining said shielding means at a temperature lower than said target.
Description
- 10982~8 1 Ba~kground of the Invention The present invention relates to ion bombardment or implantation apparatus and more particularly to such appara-tus having expedients which permit the control of surface potential of the target, particularly a target having a bombarded surface which is formed in whole or in part of ;~
an electrically insulative material.
Ion implantation is a technology of rapidly increasing importance in the ~abrication of integrated circuits, parti-cularly bipolar integrated circuits. In this bipolar tech-nology, there is an increasing demand for (1) high dosage but relatively low time cycle implantation operations, and (2~ ion implantation technology useful for introducing im- ~-purities through openings having at least one lateral di- ~-mension no greater than one mil. Since the implantation dosage is dependent on the combination of current and time, it follows that in order to achieve high dosage in relatively short time, the technology must move in the direction of high current ion implantation beams having currents greater than 0.5 ma. It has been found that when making such high current ion implantations of conductivity-determining im-purities through electrically insulative layer openings having dimensions in the order of 0.1 to 1 mil. as is re-quired in the high density, large scale integrated circuits, there is a substantial tendency toward the impairment or destruction of portions of this electrically insulative layer as well as exposed semiconductor areas resulting in potential short circuits which render the integrated circuit inoperative.
,~ ~
~ 8Z18 1 We believe that such impairment or destruction occurs clue to an electrical breakdown of a potential built up on the insulating layer arising from the charge deposited by the positive ions which make up the primary ion beam.
This potential buildup is particularly pronounced in high current beams which have a high density of positive ions. Without being bound on the theory involved, we believe that in such high current beams, positive ions have such a high density that the floating cloud of electrons, which is inherently produced through the opera-tion of the ion bombardment apparatus such as through secondary electron emission from material struck by the ion beam and neutral background gas ionization by the ion beam, is insufficient in quantity to fully neutralize the charge created by the positive ions on the target.
The concept of the positive ion beam and thQ effect of the secondary electron cloud is discussed in some de-tail in U.S. Patent No. 3,997,846, issued December 14, 1976 to D.K. Coultas, et al, U.S. Patent No. 4,011,449, issued March 8, 1977, to Wen-Chuang Ko, et al, and U.S.
Patent No. 4,013,891, issued March 22, 1977, to Wen-Chuang Ko et al, and in the article "High Current Electron Scanning Method for Ion Beam Writing", W.C. Ko, at pp.
1832 - 1835, IBM Technical Disclosure Bulletin, Vol. 18, No. 6, November 1975, as well as in the text, "Ion Beams With Application to Ion Implantation", R.G. Wilson and G.R. Brewer, (John Wiley & Sons, New York, 1973) at pp.
132 - 143.
In addition, it appears that when the openings through which the ions are to be implanted have small lateral dimensions in the order of 1 mil. or less, secondary electrons 1 which are normally produced by positive ions striking semicon-ductor substrate are minimized; this further contributes to the deficiency of available secondary electrons at the surface to neutralize the positive ion accumulation to prevent charge build-up. This effect is discussed ;n detail in copending Canadian application 289,545, H.S. Rupprecht et al, filed October 26, -1977, entitled "Method of High Current Ion Implantation".
While the problem described will arise in connection with such ion implantation through minute openings, similar problems may be expected to arise when the ion implantation is conducted with high current beams through thin regions in an electrically insulative layer over a semiconductor substrate rather than through openings in such an insulative layer.
The prior art has a suggested solution to this problem of charge buildup which involves directly irradiating the surface of the electrically insulative material with electrons in sufficient quantity to produce a negative potential on the surface of the insulative material sufficient to offset any positive charge pro-duced by the ions in the beam. We have found that when such a direct impingement method is utilized, less than desirable effects are produced. First, the electron source is usually a heated filament, metallic member of some sort, or plasma. Such electron source can be adversely affected by material emitted from the target during ion bombardment and, in addition, these sources can give off material which can contaminate the target. In ad-dition, since the electron source is conventionally a heated member such as a heated filament, the heat . . . . . . .
8Zi8 1 from the source will produce an undesirable heating effect at: the target. Thus, if the target is covered with an electrically insulative material such as photoresist which is affected by heat, then the heated filament may damage the target.
In addition, since ion beam dosimetry, i.e., the measurement and control of ion beam current, is considered to be significant in ion implantation apparatus, there is the need in the art, particularly with high current beams, for a method and apparatus for controlling and minimizing the positive surface potential of the target which is com-patible with dosimetry apparatus for measuring the beam current.
Summary of the Present Invention Accordingly, it is an object of the present invention to provide ion beam bombardment apparatus in which the buildup of positive surface charge at the target surface is minimized.
It is another object of the present invention to pro-vide ion beam bombardment apparatus in which the buildupof positive charge on a surface of insulative material formed on a semiconductor substrate is minimized.
It is yet another object of the present invention to provide ion beam bombardment apparatus in which the build-up of positive charge on a layer of electrically insula-tive material of the target is minimized along with the minimum of contamination of the target resulting from the apparatus for limiting such buildup.
10~38218 1 It is even another object of the present invention to provide ion beam bombardment apparatus in which the buildup of positive charge on a layer of electrically insulative material on the target is minimized without damaging the insulative layer, or substrate areas ex-posed in openings in the insulative layer.
It is a further object of the present invention to provide a method of ion implantation through the minute openings in insulative layers required in dense inte-grated circuits which is not subject to insulative layer breakdown or damage to areas exposed in such openings.
It is yet a further object of the present inventionto provide a method of ion bombardment utilizing high current beams which is not subject to breakdown of the insulative layer over the integrated circuit being bom-barded or damage to substrate areas exposed in openings in said insulative layer.
It is an even further object of the present invention to provide ion beam bombardment apparatus with both ion beam measurement capability and capability of minimizing the buildup of positive charge at the target surface.
It is the primary object of the present invention to provide ion bombardment apparatus for fulfilling the above objects which is free from any high temperature related problems associated with the apparatus for minimizing charge buildup.
The above and other objects of the present invention are achieved by apparatus for bombarding a target with a 1 beam of ions having a structure for controlling the sur-face potential of the target which comprises a combina-tion of an electron source adjacent to the beam for pro-viding electrons to the beam and means between the tar-get and this electron source for inhibiting direct recti-linear radiations between the source and target. Such radiations include the electrons produced by the source as well as other particulate radiation and photon radia-tion. In other words, the inhibiting means or shield pre-vents a straight line path of electrons from the electron source to the target. Consequently, there is no radiation directly projected or impinged upon the target by the elec-tron source. Also, the shield prevents material which is evaporated from the source from contaminating the target.
During the operation of the source and particularly when the source is a heated filament such as tungsten, tanta-lum or thoriated iridium, such materials are evaporated from the source. The shield prevents target contamina-tion. In addition, the shield prevents any positive ions which may incidentally be sputtered off the target by the ion beam from directly damaging or contaminating the source structure. Further, with a heated source like filament, the shield prevents the source from heating the target to thereby damage heat sensitive materials like photoresist.
The apparatus further includes means for maintaining the shield means at lower temperature than said target. This is particularly desirable where the source of electrons is a heated source such as a conventional electron emitting filament.
~L0~8218 1 In accordance with another aspect of the present invention, the apparatus for ion bombarding the target with a beam of ions includes a structure for measuring the ion beam current and controlling the surface poten-tial of the target which comprises walls adjacent to and electrically insulated from the target and surrounding the beam whereby the walls and target provide a Faraday Cage, means for providing variable quantities of electrons within the Faraday Cage, means for measuring the target current, means for combining and measuring the target and wall currents to provide said ion beam current measure-ment, and means for varying the quantities of provided electrons to control the target current and thereby said target surface potential. Likewise, this apparatus fur-ther includes means for maintaining the shielding means at a temperature lower than the target. -The key to this latter aspect of the present inven-tion resides in the ability to monitor or measure the net target current which is an indicator of the surface potential of the target being bombarded. However, since the target current also represents an essential part of any ion beam current measurement, the Faraday Cage must be so arranged that walls are electrically insulated from the target, i.e., the total wall current is measured separately from the target current; then, the target cur-rent and the wall current may be combined to provide the ;
ion beam current measurement.
~ ;
2i8 1 Utilizing the apparatus of the present invention, the target having layers of electrically insulative material thereon such as semiconductor wafers coated with insulative layers may be ion implanted while minimizing positive charge buildup on the insulative surface even when utilizing high current ion beams having current of at least 0.5 ma. The positive charge buildup is avoided by monitoring the target current. So long as the target current is maintained at zero or at a negative level, pre-ferably a slightly negative level, the positive potential buildup on the target insulative layer surface cannot occur. The target current may be adjusted by varying the quantities of electrons being introduced in the apparatus.
This may be accomplished by conventional variations in the operating conditions of the electron source.
The foregoing and other objects, features and advan-tages of the invention will be apparent from the follow-ing more particular description of the preferred embodi-ments of the invention, as illustrated in the accompany-ing drawings.
Brief Description of the Drawings FIG. 1 discloses a schematic representation of an ion implantation apparatus in order to illustrate the operative association of the overall apparatus to the structure of the present invention for controlling target surface potential and for measuring beam current;
the apparatus of the present invention is shown in greater detail in FIG. lA which is an enlargement of the portion 10~38218 1 defined by the dashed lines and shown in a partial sec-tional view in FIG. 1.
FIG. 2 is a partial sectional view of an alternate ernbodiment of the current-measuring and target-surface potential-controlling apparatus of the present invention.
FIG. 3A is a fragmentary front view of a portion of the apparatus for controlling the target surface potential containing a modification for cooling the electron shield;
the view is taken from the target position looking along the axis of the beam.
FIG. 3B is a diagrammatic partial sectional view of the apparatus in FIG. 3A taken along lines 3B -3B.
Description of Preferred Embodiments In FIGS. 1, lA and 2, there is shown the apparatus of the invention in Canadian Application No. 298,328, filed March 2, 1978, by J.F. Forneris et al, entitled "Ion Implantation Apparatus for Controlling the Surface - -Potential of a Target Surface". The apparatus of said co-pending application provides means for controlling the surface potential of the target being implanted by providing electrons to the beam and including means be-tween the target and the electron source for inhibit-ing direct rectilinear radiations between the target and source. The invention of the present applicatlon is a -modification of the apparatus shown in FIGS. 1, lA and
an electrically insulative material.
Ion implantation is a technology of rapidly increasing importance in the ~abrication of integrated circuits, parti-cularly bipolar integrated circuits. In this bipolar tech-nology, there is an increasing demand for (1) high dosage but relatively low time cycle implantation operations, and (2~ ion implantation technology useful for introducing im- ~-purities through openings having at least one lateral di- ~-mension no greater than one mil. Since the implantation dosage is dependent on the combination of current and time, it follows that in order to achieve high dosage in relatively short time, the technology must move in the direction of high current ion implantation beams having currents greater than 0.5 ma. It has been found that when making such high current ion implantations of conductivity-determining im-purities through electrically insulative layer openings having dimensions in the order of 0.1 to 1 mil. as is re-quired in the high density, large scale integrated circuits, there is a substantial tendency toward the impairment or destruction of portions of this electrically insulative layer as well as exposed semiconductor areas resulting in potential short circuits which render the integrated circuit inoperative.
,~ ~
~ 8Z18 1 We believe that such impairment or destruction occurs clue to an electrical breakdown of a potential built up on the insulating layer arising from the charge deposited by the positive ions which make up the primary ion beam.
This potential buildup is particularly pronounced in high current beams which have a high density of positive ions. Without being bound on the theory involved, we believe that in such high current beams, positive ions have such a high density that the floating cloud of electrons, which is inherently produced through the opera-tion of the ion bombardment apparatus such as through secondary electron emission from material struck by the ion beam and neutral background gas ionization by the ion beam, is insufficient in quantity to fully neutralize the charge created by the positive ions on the target.
The concept of the positive ion beam and thQ effect of the secondary electron cloud is discussed in some de-tail in U.S. Patent No. 3,997,846, issued December 14, 1976 to D.K. Coultas, et al, U.S. Patent No. 4,011,449, issued March 8, 1977, to Wen-Chuang Ko, et al, and U.S.
Patent No. 4,013,891, issued March 22, 1977, to Wen-Chuang Ko et al, and in the article "High Current Electron Scanning Method for Ion Beam Writing", W.C. Ko, at pp.
1832 - 1835, IBM Technical Disclosure Bulletin, Vol. 18, No. 6, November 1975, as well as in the text, "Ion Beams With Application to Ion Implantation", R.G. Wilson and G.R. Brewer, (John Wiley & Sons, New York, 1973) at pp.
132 - 143.
In addition, it appears that when the openings through which the ions are to be implanted have small lateral dimensions in the order of 1 mil. or less, secondary electrons 1 which are normally produced by positive ions striking semicon-ductor substrate are minimized; this further contributes to the deficiency of available secondary electrons at the surface to neutralize the positive ion accumulation to prevent charge build-up. This effect is discussed ;n detail in copending Canadian application 289,545, H.S. Rupprecht et al, filed October 26, -1977, entitled "Method of High Current Ion Implantation".
While the problem described will arise in connection with such ion implantation through minute openings, similar problems may be expected to arise when the ion implantation is conducted with high current beams through thin regions in an electrically insulative layer over a semiconductor substrate rather than through openings in such an insulative layer.
The prior art has a suggested solution to this problem of charge buildup which involves directly irradiating the surface of the electrically insulative material with electrons in sufficient quantity to produce a negative potential on the surface of the insulative material sufficient to offset any positive charge pro-duced by the ions in the beam. We have found that when such a direct impingement method is utilized, less than desirable effects are produced. First, the electron source is usually a heated filament, metallic member of some sort, or plasma. Such electron source can be adversely affected by material emitted from the target during ion bombardment and, in addition, these sources can give off material which can contaminate the target. In ad-dition, since the electron source is conventionally a heated member such as a heated filament, the heat . . . . . . .
8Zi8 1 from the source will produce an undesirable heating effect at: the target. Thus, if the target is covered with an electrically insulative material such as photoresist which is affected by heat, then the heated filament may damage the target.
In addition, since ion beam dosimetry, i.e., the measurement and control of ion beam current, is considered to be significant in ion implantation apparatus, there is the need in the art, particularly with high current beams, for a method and apparatus for controlling and minimizing the positive surface potential of the target which is com-patible with dosimetry apparatus for measuring the beam current.
Summary of the Present Invention Accordingly, it is an object of the present invention to provide ion beam bombardment apparatus in which the buildup of positive surface charge at the target surface is minimized.
It is another object of the present invention to pro-vide ion beam bombardment apparatus in which the buildupof positive charge on a surface of insulative material formed on a semiconductor substrate is minimized.
It is yet another object of the present invention to provide ion beam bombardment apparatus in which the build-up of positive charge on a layer of electrically insula-tive material of the target is minimized along with the minimum of contamination of the target resulting from the apparatus for limiting such buildup.
10~38218 1 It is even another object of the present invention to provide ion beam bombardment apparatus in which the buildup of positive charge on a layer of electrically insulative material on the target is minimized without damaging the insulative layer, or substrate areas ex-posed in openings in the insulative layer.
It is a further object of the present invention to provide a method of ion implantation through the minute openings in insulative layers required in dense inte-grated circuits which is not subject to insulative layer breakdown or damage to areas exposed in such openings.
It is yet a further object of the present inventionto provide a method of ion bombardment utilizing high current beams which is not subject to breakdown of the insulative layer over the integrated circuit being bom-barded or damage to substrate areas exposed in openings in said insulative layer.
It is an even further object of the present invention to provide ion beam bombardment apparatus with both ion beam measurement capability and capability of minimizing the buildup of positive charge at the target surface.
It is the primary object of the present invention to provide ion bombardment apparatus for fulfilling the above objects which is free from any high temperature related problems associated with the apparatus for minimizing charge buildup.
The above and other objects of the present invention are achieved by apparatus for bombarding a target with a 1 beam of ions having a structure for controlling the sur-face potential of the target which comprises a combina-tion of an electron source adjacent to the beam for pro-viding electrons to the beam and means between the tar-get and this electron source for inhibiting direct recti-linear radiations between the source and target. Such radiations include the electrons produced by the source as well as other particulate radiation and photon radia-tion. In other words, the inhibiting means or shield pre-vents a straight line path of electrons from the electron source to the target. Consequently, there is no radiation directly projected or impinged upon the target by the elec-tron source. Also, the shield prevents material which is evaporated from the source from contaminating the target.
During the operation of the source and particularly when the source is a heated filament such as tungsten, tanta-lum or thoriated iridium, such materials are evaporated from the source. The shield prevents target contamina-tion. In addition, the shield prevents any positive ions which may incidentally be sputtered off the target by the ion beam from directly damaging or contaminating the source structure. Further, with a heated source like filament, the shield prevents the source from heating the target to thereby damage heat sensitive materials like photoresist.
The apparatus further includes means for maintaining the shield means at lower temperature than said target. This is particularly desirable where the source of electrons is a heated source such as a conventional electron emitting filament.
~L0~8218 1 In accordance with another aspect of the present invention, the apparatus for ion bombarding the target with a beam of ions includes a structure for measuring the ion beam current and controlling the surface poten-tial of the target which comprises walls adjacent to and electrically insulated from the target and surrounding the beam whereby the walls and target provide a Faraday Cage, means for providing variable quantities of electrons within the Faraday Cage, means for measuring the target current, means for combining and measuring the target and wall currents to provide said ion beam current measure-ment, and means for varying the quantities of provided electrons to control the target current and thereby said target surface potential. Likewise, this apparatus fur-ther includes means for maintaining the shielding means at a temperature lower than the target. -The key to this latter aspect of the present inven-tion resides in the ability to monitor or measure the net target current which is an indicator of the surface potential of the target being bombarded. However, since the target current also represents an essential part of any ion beam current measurement, the Faraday Cage must be so arranged that walls are electrically insulated from the target, i.e., the total wall current is measured separately from the target current; then, the target cur-rent and the wall current may be combined to provide the ;
ion beam current measurement.
~ ;
2i8 1 Utilizing the apparatus of the present invention, the target having layers of electrically insulative material thereon such as semiconductor wafers coated with insulative layers may be ion implanted while minimizing positive charge buildup on the insulative surface even when utilizing high current ion beams having current of at least 0.5 ma. The positive charge buildup is avoided by monitoring the target current. So long as the target current is maintained at zero or at a negative level, pre-ferably a slightly negative level, the positive potential buildup on the target insulative layer surface cannot occur. The target current may be adjusted by varying the quantities of electrons being introduced in the apparatus.
This may be accomplished by conventional variations in the operating conditions of the electron source.
The foregoing and other objects, features and advan-tages of the invention will be apparent from the follow-ing more particular description of the preferred embodi-ments of the invention, as illustrated in the accompany-ing drawings.
Brief Description of the Drawings FIG. 1 discloses a schematic representation of an ion implantation apparatus in order to illustrate the operative association of the overall apparatus to the structure of the present invention for controlling target surface potential and for measuring beam current;
the apparatus of the present invention is shown in greater detail in FIG. lA which is an enlargement of the portion 10~38218 1 defined by the dashed lines and shown in a partial sec-tional view in FIG. 1.
FIG. 2 is a partial sectional view of an alternate ernbodiment of the current-measuring and target-surface potential-controlling apparatus of the present invention.
FIG. 3A is a fragmentary front view of a portion of the apparatus for controlling the target surface potential containing a modification for cooling the electron shield;
the view is taken from the target position looking along the axis of the beam.
FIG. 3B is a diagrammatic partial sectional view of the apparatus in FIG. 3A taken along lines 3B -3B.
Description of Preferred Embodiments In FIGS. 1, lA and 2, there is shown the apparatus of the invention in Canadian Application No. 298,328, filed March 2, 1978, by J.F. Forneris et al, entitled "Ion Implantation Apparatus for Controlling the Surface - -Potential of a Target Surface". The apparatus of said co-pending application provides means for controlling the surface potential of the target being implanted by providing electrons to the beam and including means be-tween the target and the electron source for inhibit-ing direct rectilinear radiations between the target and source. The invention of the present applicatlon is a -modification of the apparatus shown in FIGS. 1, lA and
2 to include means for ensuring that the radiation inhi-biting or shielding means between the source of electrons and the target is cooled so as to be maintained at a temp-erature below that of the target. This cooling apparatus is described in detail ~OB8Zl~
1 with reference to FIGS. 3A and 3B.
Referring now to the drawings and initially to FIG. 1, the structure of the present invention for measuring the ion beam current and controlling the sur-face potential of the target is shown within the dashed lines 10 as it is related to a conventional ion implanta-tion apparatus. It should be recognized that the remain-der of the apparatus in FIG. 1 outside of box 10 is schematic in nature and represents conventional ion im-plantation apparatus such as that described in U.S. Patent No. 3,756,862, issued September 4, 1973, to J. Ahn et al.
The apparatus in FIG. 1 includes a conventional ion source 12 which may be any suitable high density source, although in the embodiments illustrated, a hot filament electron impact source is shown adapted to be operated in an oscillating electron discharge mode. An ion beam is extracted from the source in the conventional manner ~;~
through extraction electrode 16 via aperture 15. Elec- ~-trode 16 which is also known as an accel-electrode is ~; 20 -maintained at a negative potential by the decel supply.
The source electrode 17 is maintained at a positive potential with respect to filament 12 by the anode sup-ply. A decel-electrode 18 is also provided, adapted to be maintained at ground potential. It should be recog-nized that the bias voltages described may be varied in the operations of the device by those skilled in the art.
The beam extracted from the ion source by the elec- -trode arrangement disclosed is transmitted along a beam path generally indicated at 19 to an analyzing magnet 20 of conventional design. The beam is further defined in the conventional manner by apertured plates 21 and 22 located ',, i ' . '- : : , .
lQB8Z18 1 on either side of the analyzing magent. A conventional beam defining aperture 24 is included in the apparatus as illustrated. Then, the beam is further deflned by aperture 26 formed in plates 25 and strikes target 23.
Now with particular reference to the struc~ure of the present invention which permits the control of the surface potential of the target while practicing accurate dosimetry, i.e., measurement of the ion beam current, reference is made to the structure shown diagrammatically within dashed line box 10 which is enlarged in FIG. lA.
The structure is a modified Faraday Cage structure of the type described in the aforementioned U.S. Patent No. ;
4,011,449, used to measure the beam current. Target 23 combines with adjacent walls 27 and rear walls 28 to -form a Faraday Cage structure surrounding ion beam 29. ~-Target 23 comprises a semiconductor wafer holder 30 sup~
porting a plurality of wafers 31. The wafer holder is rotated and oscillated in the direction indicated by a standard deflection apparatus such as that described in U.S. Patent No. 3,778,626, issued December, 1973, to Robertson, in order to ensure uniform distribution of the ion beam 29 across the surfaces of all of the wafers 31 mounted on the target support 30. Alternatively, of course, the Faraday Cage arrangement of the present invention may function with a stationary target 23. The ~ Faraday Cage including the target is enclosed in any ;- suitable conventional chamber (not shown) for maintain-~ ing a high vacuum in the ion implantation apparatus.
:; ~
~ Adjacent walls or side walls 27 must be electrically :
L~r~
... ~ . .. . . .
,:' ' ' - , 1~8Zl~
1 insulated from target 23. In the present embodiment it is shown spaced from target 23. Side walls 27 are biased at a more negative potential than the potential being applied to target 23. In the embodiment shown, target 23 is biased at ground through connector 32 and walls 27 are biased more negatively with respect to ground by supply V . Electron sources 33 and 33' are conventional electron w sources designed to introduce variable quantities of elec-trons 34 into ion beam 29 in order to have a sufficient quantity of electrons in the region of the ion beam to neutralize any charge buildup which may result in an un-desirable positive potential formed at the surface of wafer 31 being implanted. The problem of such an undesir-able charge buildup particularly when high current ion beams, i.e., ion beams having currents of at least 0.5 ma., are used to bombard or implant semiconductor wafers having only minute openings or no openings at all through insula-tive layers has been discussed above. Electron sources 33 and 33' may be any conventional source of electrons such as a heated filament which emits electrons. Alter-natively, it may be conventional plasma bridges, elec-tron guns with or without magnetic fields or field emission electrodes. The electron source filament 35 is supplied by a conventional power supply, not shown, which may be varied to increase or decrease a current through filament 35 and thereby to increase or decrease the electrons 34 which are being emitted into the path of ion beam 29. The filament is preferably biased by biasing voltage VF to a negative level with respect to side walls 27. It is impor-tant that electron sources 33 and 33' be ~n~38~8 1 set into recesses formed in side walls 27 to such an ex-tent that there is no rectilinear or line-of-sight path connecting any part of the filament to any part of the wafer; the wall portions 36 of walls 27 act to shield against such a path.
Rear wall 28 is separated from side wall 27 by a layer of electrically insulative material 37. Voltage supply Vp serves to bias the rear wall 28 as the most ne~ative with respect to side walls 27 and filament 35.
With the biasing arrangement shown, the electrons 34 introduced into the beam as well as the secondary elec-tron cloud which accompanies the ion beam are contained within Faraday Cage formed by rear walls 28, side walls 27 and target 23, and are moved away from the walls in the direction toward the target. ~he following are some typi~
.
cal operating parameters. When utilizing apparatus operat-ing at an energy level in the order of 50 Kev. with ions such as arsenic, and beam currents in the order of 0.5 ma.
or higher, best results are achieved by maintaining the -~
target at ground potential, a bias on side walls 27 of about -50 volts, a total bias on the filaments 35 of about -60 to -100 volts and a total bias on rear walls 28 of -200 volts. The beam current measurement is deter-mined by combining the current from all of the elements, i.e., the current from target 23, from side walls 27 and from rear wall 28 at ammeter 38 to provide a reading of the beam current in a manner similar to that described in aforementioned U.S. Patent No. 4,011,449. At the same time, the target :~
.-: :
- lO~Z18 l current alone may be monitored through ammeter 39 to pro-vide a reading of the target current which permits the adjustment of the electrons 34 being introduced into the beam 29 from filament 35. As set forth hereinabove, in order to prevent a buildup of a positive potential on any insulative layer formed on the surface of a target wafer 31, it is desirable that the target current be either at zero or negative to some extent.
In the structure of FIG. lA, the function of rear wall 28 which is biased at the most negative level in the Faraday Cage is to ensure that a minimum of the electrons will exit the Faraday Cage from the open rear of the cage. -In a modified alternate embodiment of this structure as shown in FIG. 3, rear wall 28 may be eliminated and a magnetic field 40 perpendicular to the ion beam may be created by a pair of magnets 41 and 42. This field will substantially prevent any rearward movement of the elec-trons associated with ion beam 26 by functioning in the conventional manner as an electron barrier.
With ion beams implanting certain dopants such as arsenic which evaporate readily under operating tempera-tures, a problem may arise due to the precipitation of evaporated arsenic on the target. In the standard operat-ion of ion implanti~n equipment, any arsenic which is evaporated during the operations would precipitate on the walls of the Faraday Cage adjacent to the target. How-'~
ever, where as is the case with the present structure, electrons are being provided to the ion beam from a heated source such as a filament 35 which operates at temperatures in ~0~3t3218 1 the order of from 1500 to 2700C, the walls 27 and particularly the shield portions 36 thereof become quite hot. Because the walls and shield are at a higher temperature than the target, any arsenic vapor tends to deposit on the target wafer surface. This distorts the processing and particularly the arsenic doping level measured from the implantation of arsenic. This occurs because the evaporated arsenic is not in the ionic state (it is essentially neutral) and consequently, is not measured by the dosimetry apparatus during the implanta- -~
tion stage. However, since it is deposited on the wafer surface, it is driven into the wafer during subsequent high heat processing stages of the wafer. Consequently, quantities of arsenic which are not accounted for by the ion implantation dosimetry end up in the wafer and there-by potentially will distort the desired implantation dos-ages and dopant concentration levels in the wafer.
In addition, arsenic which may have been plated on to the structure walls during a previous implantation cycle may be evaporated from the walls during a subsequent implantation cycle to adversely affect the dosimetxy in ~-the subsequent cycle.
Accordingly, the above mentioned copending Forneris et al application provides for cooled shield and wall members in apparatus which is particularly useful for the bombardment or implantation with materials such as arsenic which readily vapori~e under operating conditions.
In such cooled structures, the structure of the present invention as shown in FIG. lA is modified in accordance ~OB~218 1 with the teaching of the aforesaid Canadian Application No. 298,328, as shown in FIG. 3B which is a sectional view taken along lines 3B - 3B of Fig. 3A. FIG. 3A is a front view of the implantation apparatus taken from the target facing the beam along the axis of the beam. Be-cause much of the apparatus in FIGS. 3A and 3s are sub-stantially the same as that shown in FIG~S. 1 and lA, for convenience in illustration and description the elements in FIGS. 3A and 3B which are equivalent to elements in FIGS. 1 and lA will be designated with the same numbers as the elements in FIGS. 1 and lA preceded by the digit "1", e.g., side wall 27 in FIG. lA is equivalent to side wall 127 in FIGS. 3A and 3B. In this manner, when an element in FIGS. 3A and 3B is mentioned which is the equivalent of an element in FIGS. 1 and lA no further description will be made and it will be assumed that it operates in the same manner as in the original structure.
In FIGS. 3A and 3B, wafers 131 are being implanted with ion beam 129. The wafers are mounted on target support -~
130 of target structure 123. Side walls 127 are modi-fied to contain cooling conduits 150 uhich are connected to input conduit 151 through which fluid enters the cool-ing system and conduit 152 through which fluid exits the cooling system. A coolant such as compressed air or fluoro-- carbon coolant may be passed through the conduits to cool walls 127 and particularly shielding portions 136 thereof ~`~ to maintain these walls at a temperature below that of :. ~
the target irrespective of the temperature of filaments 135 which introduce electrons 13~ into the ion beam 129.
The coolants used must be electrically 10~8218 1 insulative in character so that they do not affect the dosimetry, i.e., the ion beam measurement operation of the apparatus. Likewise, the external portions of the cooling system should be electrically insulated from the walls of the Faraday Cage. As shown in FIG. ~A, connectors 153 are made of electrically insulative mater-ial and act to insulate conduits 151 and 152 from walls -127.
In FIG. 3A, a section is broken away to show the disposition of one of the filaments 135 of electron source member 133 with respect to beam 129. In all other respects, the elements of FIGS. 3A and 3B function in substantially the same manner as their equivalent ele-ments in FIGS. 1 and lA. Further, the cooled beam-cur-rent-measuring and surface-potential-controlling appara-tus shown in FIGS. 3A and 3B is used in combination with conventional ion implantation apparatus, the remainder of which is diagrammatically shown in FIG. 1.
With the cooling apparatus described, when the fila-ment is heated to temperatures in the order of 1500 to 2700C, the walls 136 are maintained at less than 100C
during ion beam operation, while the target which is heated mainly by the ion beam reaches a higher tempera-ture of about 150C.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
1 with reference to FIGS. 3A and 3B.
Referring now to the drawings and initially to FIG. 1, the structure of the present invention for measuring the ion beam current and controlling the sur-face potential of the target is shown within the dashed lines 10 as it is related to a conventional ion implanta-tion apparatus. It should be recognized that the remain-der of the apparatus in FIG. 1 outside of box 10 is schematic in nature and represents conventional ion im-plantation apparatus such as that described in U.S. Patent No. 3,756,862, issued September 4, 1973, to J. Ahn et al.
The apparatus in FIG. 1 includes a conventional ion source 12 which may be any suitable high density source, although in the embodiments illustrated, a hot filament electron impact source is shown adapted to be operated in an oscillating electron discharge mode. An ion beam is extracted from the source in the conventional manner ~;~
through extraction electrode 16 via aperture 15. Elec- ~-trode 16 which is also known as an accel-electrode is ~; 20 -maintained at a negative potential by the decel supply.
The source electrode 17 is maintained at a positive potential with respect to filament 12 by the anode sup-ply. A decel-electrode 18 is also provided, adapted to be maintained at ground potential. It should be recog-nized that the bias voltages described may be varied in the operations of the device by those skilled in the art.
The beam extracted from the ion source by the elec- -trode arrangement disclosed is transmitted along a beam path generally indicated at 19 to an analyzing magnet 20 of conventional design. The beam is further defined in the conventional manner by apertured plates 21 and 22 located ',, i ' . '- : : , .
lQB8Z18 1 on either side of the analyzing magent. A conventional beam defining aperture 24 is included in the apparatus as illustrated. Then, the beam is further deflned by aperture 26 formed in plates 25 and strikes target 23.
Now with particular reference to the struc~ure of the present invention which permits the control of the surface potential of the target while practicing accurate dosimetry, i.e., measurement of the ion beam current, reference is made to the structure shown diagrammatically within dashed line box 10 which is enlarged in FIG. lA.
The structure is a modified Faraday Cage structure of the type described in the aforementioned U.S. Patent No. ;
4,011,449, used to measure the beam current. Target 23 combines with adjacent walls 27 and rear walls 28 to -form a Faraday Cage structure surrounding ion beam 29. ~-Target 23 comprises a semiconductor wafer holder 30 sup~
porting a plurality of wafers 31. The wafer holder is rotated and oscillated in the direction indicated by a standard deflection apparatus such as that described in U.S. Patent No. 3,778,626, issued December, 1973, to Robertson, in order to ensure uniform distribution of the ion beam 29 across the surfaces of all of the wafers 31 mounted on the target support 30. Alternatively, of course, the Faraday Cage arrangement of the present invention may function with a stationary target 23. The ~ Faraday Cage including the target is enclosed in any ;- suitable conventional chamber (not shown) for maintain-~ ing a high vacuum in the ion implantation apparatus.
:; ~
~ Adjacent walls or side walls 27 must be electrically :
L~r~
... ~ . .. . . .
,:' ' ' - , 1~8Zl~
1 insulated from target 23. In the present embodiment it is shown spaced from target 23. Side walls 27 are biased at a more negative potential than the potential being applied to target 23. In the embodiment shown, target 23 is biased at ground through connector 32 and walls 27 are biased more negatively with respect to ground by supply V . Electron sources 33 and 33' are conventional electron w sources designed to introduce variable quantities of elec-trons 34 into ion beam 29 in order to have a sufficient quantity of electrons in the region of the ion beam to neutralize any charge buildup which may result in an un-desirable positive potential formed at the surface of wafer 31 being implanted. The problem of such an undesir-able charge buildup particularly when high current ion beams, i.e., ion beams having currents of at least 0.5 ma., are used to bombard or implant semiconductor wafers having only minute openings or no openings at all through insula-tive layers has been discussed above. Electron sources 33 and 33' may be any conventional source of electrons such as a heated filament which emits electrons. Alter-natively, it may be conventional plasma bridges, elec-tron guns with or without magnetic fields or field emission electrodes. The electron source filament 35 is supplied by a conventional power supply, not shown, which may be varied to increase or decrease a current through filament 35 and thereby to increase or decrease the electrons 34 which are being emitted into the path of ion beam 29. The filament is preferably biased by biasing voltage VF to a negative level with respect to side walls 27. It is impor-tant that electron sources 33 and 33' be ~n~38~8 1 set into recesses formed in side walls 27 to such an ex-tent that there is no rectilinear or line-of-sight path connecting any part of the filament to any part of the wafer; the wall portions 36 of walls 27 act to shield against such a path.
Rear wall 28 is separated from side wall 27 by a layer of electrically insulative material 37. Voltage supply Vp serves to bias the rear wall 28 as the most ne~ative with respect to side walls 27 and filament 35.
With the biasing arrangement shown, the electrons 34 introduced into the beam as well as the secondary elec-tron cloud which accompanies the ion beam are contained within Faraday Cage formed by rear walls 28, side walls 27 and target 23, and are moved away from the walls in the direction toward the target. ~he following are some typi~
.
cal operating parameters. When utilizing apparatus operat-ing at an energy level in the order of 50 Kev. with ions such as arsenic, and beam currents in the order of 0.5 ma.
or higher, best results are achieved by maintaining the -~
target at ground potential, a bias on side walls 27 of about -50 volts, a total bias on the filaments 35 of about -60 to -100 volts and a total bias on rear walls 28 of -200 volts. The beam current measurement is deter-mined by combining the current from all of the elements, i.e., the current from target 23, from side walls 27 and from rear wall 28 at ammeter 38 to provide a reading of the beam current in a manner similar to that described in aforementioned U.S. Patent No. 4,011,449. At the same time, the target :~
.-: :
- lO~Z18 l current alone may be monitored through ammeter 39 to pro-vide a reading of the target current which permits the adjustment of the electrons 34 being introduced into the beam 29 from filament 35. As set forth hereinabove, in order to prevent a buildup of a positive potential on any insulative layer formed on the surface of a target wafer 31, it is desirable that the target current be either at zero or negative to some extent.
In the structure of FIG. lA, the function of rear wall 28 which is biased at the most negative level in the Faraday Cage is to ensure that a minimum of the electrons will exit the Faraday Cage from the open rear of the cage. -In a modified alternate embodiment of this structure as shown in FIG. 3, rear wall 28 may be eliminated and a magnetic field 40 perpendicular to the ion beam may be created by a pair of magnets 41 and 42. This field will substantially prevent any rearward movement of the elec-trons associated with ion beam 26 by functioning in the conventional manner as an electron barrier.
With ion beams implanting certain dopants such as arsenic which evaporate readily under operating tempera-tures, a problem may arise due to the precipitation of evaporated arsenic on the target. In the standard operat-ion of ion implanti~n equipment, any arsenic which is evaporated during the operations would precipitate on the walls of the Faraday Cage adjacent to the target. How-'~
ever, where as is the case with the present structure, electrons are being provided to the ion beam from a heated source such as a filament 35 which operates at temperatures in ~0~3t3218 1 the order of from 1500 to 2700C, the walls 27 and particularly the shield portions 36 thereof become quite hot. Because the walls and shield are at a higher temperature than the target, any arsenic vapor tends to deposit on the target wafer surface. This distorts the processing and particularly the arsenic doping level measured from the implantation of arsenic. This occurs because the evaporated arsenic is not in the ionic state (it is essentially neutral) and consequently, is not measured by the dosimetry apparatus during the implanta- -~
tion stage. However, since it is deposited on the wafer surface, it is driven into the wafer during subsequent high heat processing stages of the wafer. Consequently, quantities of arsenic which are not accounted for by the ion implantation dosimetry end up in the wafer and there-by potentially will distort the desired implantation dos-ages and dopant concentration levels in the wafer.
In addition, arsenic which may have been plated on to the structure walls during a previous implantation cycle may be evaporated from the walls during a subsequent implantation cycle to adversely affect the dosimetxy in ~-the subsequent cycle.
Accordingly, the above mentioned copending Forneris et al application provides for cooled shield and wall members in apparatus which is particularly useful for the bombardment or implantation with materials such as arsenic which readily vapori~e under operating conditions.
In such cooled structures, the structure of the present invention as shown in FIG. lA is modified in accordance ~OB~218 1 with the teaching of the aforesaid Canadian Application No. 298,328, as shown in FIG. 3B which is a sectional view taken along lines 3B - 3B of Fig. 3A. FIG. 3A is a front view of the implantation apparatus taken from the target facing the beam along the axis of the beam. Be-cause much of the apparatus in FIGS. 3A and 3s are sub-stantially the same as that shown in FIG~S. 1 and lA, for convenience in illustration and description the elements in FIGS. 3A and 3B which are equivalent to elements in FIGS. 1 and lA will be designated with the same numbers as the elements in FIGS. 1 and lA preceded by the digit "1", e.g., side wall 27 in FIG. lA is equivalent to side wall 127 in FIGS. 3A and 3B. In this manner, when an element in FIGS. 3A and 3B is mentioned which is the equivalent of an element in FIGS. 1 and lA no further description will be made and it will be assumed that it operates in the same manner as in the original structure.
In FIGS. 3A and 3B, wafers 131 are being implanted with ion beam 129. The wafers are mounted on target support -~
130 of target structure 123. Side walls 127 are modi-fied to contain cooling conduits 150 uhich are connected to input conduit 151 through which fluid enters the cool-ing system and conduit 152 through which fluid exits the cooling system. A coolant such as compressed air or fluoro-- carbon coolant may be passed through the conduits to cool walls 127 and particularly shielding portions 136 thereof ~`~ to maintain these walls at a temperature below that of :. ~
the target irrespective of the temperature of filaments 135 which introduce electrons 13~ into the ion beam 129.
The coolants used must be electrically 10~8218 1 insulative in character so that they do not affect the dosimetry, i.e., the ion beam measurement operation of the apparatus. Likewise, the external portions of the cooling system should be electrically insulated from the walls of the Faraday Cage. As shown in FIG. ~A, connectors 153 are made of electrically insulative mater-ial and act to insulate conduits 151 and 152 from walls -127.
In FIG. 3A, a section is broken away to show the disposition of one of the filaments 135 of electron source member 133 with respect to beam 129. In all other respects, the elements of FIGS. 3A and 3B function in substantially the same manner as their equivalent ele-ments in FIGS. 1 and lA. Further, the cooled beam-cur-rent-measuring and surface-potential-controlling appara-tus shown in FIGS. 3A and 3B is used in combination with conventional ion implantation apparatus, the remainder of which is diagrammatically shown in FIG. 1.
With the cooling apparatus described, when the fila-ment is heated to temperatures in the order of 1500 to 2700C, the walls 136 are maintained at less than 100C
during ion beam operation, while the target which is heated mainly by the ion beam reaches a higher tempera-ture of about 150C.
While the invention has been particularly shown and described with reference to the preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.
Claims (10)
1. In apparatus for bombarding a target with a beam of ions, a structure for controlling the surface charge of the target comprising an electron source adjacent to the ion beam for providing electrons to said beam, means between said target and said electron source for in-hibiting direct rectilinear radiations between said source and said target, and means for maintaining said inhibiting means at a lower temperature than said target.
2. The apparatus of Claim 1 wherein said electron source is a heated source.
3. The apparatus of Claim 2 wherein said means for maintaining said inhibiting means at said lower temperature includes means for providing a fluid coolant to said inhibiting means.
4. The apparatus of Claim 2 wherein said inhibiting means includes a wall between said target and source shielding the target from said radiations, said wall having conduits formed therein, and means for providing a fluid coolant to said conduits, said coolant and conduit means providing lower temperature maintaining means.
5. In apparatus for bombarding a target with a beam of ions, a structure for measuring the ion beam current and controlling the surface charge of the target comprising:
walls adjacent to and electrically insulated from said target and surrounding said beam whereby said walls and target provide a Faraday Cage, means for providing variable quantities of electrons within said Faraday Cage, means within said cage between said target and said elec-tron source for inhibiting direct rectilinear radiations between said source and said target, means for maintaining said inhibiting means at a lower temperature than said target, means for measuring the target current, means for combining and measuring the target and the wall currents to provide said ion beam current measurement, and means for varying said quantities of provided electrons to control said target surface charge and thereby said target current.
walls adjacent to and electrically insulated from said target and surrounding said beam whereby said walls and target provide a Faraday Cage, means for providing variable quantities of electrons within said Faraday Cage, means within said cage between said target and said elec-tron source for inhibiting direct rectilinear radiations between said source and said target, means for maintaining said inhibiting means at a lower temperature than said target, means for measuring the target current, means for combining and measuring the target and the wall currents to provide said ion beam current measurement, and means for varying said quantities of provided electrons to control said target surface charge and thereby said target current.
6. The apparatus of claim 5 wherein said walls have at least one recess formed therein and said electron source is so positioned in said recess that the portion of said walls defining said recess shield said target from said source, and said lower temperature maintaining means comprises conduits formed in said walls adjacent said recess and means for providing a fluid coolant to said conduits.
7. The apparatus of claim 1, claim 5 or claim 6 wherein said electron source is a heated filament source.
8. In apparatus as defined in claim 1 wherein said means for inhibiting direct radiations is provided by walls adjacent to the target and surrounding said ion beam.
9. In the method of bombarding a target with a beam of ions, steps for controlling the surface charge of the target com-prising providing electrons to said beam from a heated source, inhibiting direct rectilinear radiations between said source and target, and maintaining said inhibiting means at a lower temperature than said target.
10. In the method of claim 9 in which the beam of charged ions is bombarding said target by a Faraday Cage formed by said tar-get and walls adjacent to the target, said method of control-ling the surface charge of the target additionally comprising electrically insulating said target from said walls, providing said electrons to said beam from said heated source within said Faraday Cage, measuring the target current, combining and measuring the target and the wall currents to provide an ion beam current measurement, and varying said quantities of provided electrons to control said target surface charge and thereby said target current.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/794,275 US4118630A (en) | 1977-05-05 | 1977-05-05 | Ion implantation apparatus with a cooled structure controlling the surface potential of a target surface |
| US794,275 | 1977-05-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1088218A true CA1088218A (en) | 1980-10-21 |
Family
ID=25162193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA299,581A Expired CA1088218A (en) | 1977-05-05 | 1978-03-22 | Ion implantation apparatus with a cooled structure controlling the surface potential of a target surface |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US4118630A (en) |
| JP (1) | JPS5842939B2 (en) |
| AU (1) | AU516164B2 (en) |
| BR (1) | BR7802843A (en) |
| CA (1) | CA1088218A (en) |
| SE (1) | SE424679B (en) |
Families Citing this family (26)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5839376B2 (en) * | 1978-10-30 | 1983-08-30 | 富士通株式会社 | Ion implantation method |
| US4234797A (en) * | 1979-05-23 | 1980-11-18 | Nova Associates, Inc. | Treating workpieces with beams |
| US4247781A (en) * | 1979-06-29 | 1981-01-27 | International Business Machines Corporation | Cooled target disc for high current ion implantation method and apparatus |
| US4261762A (en) * | 1979-09-14 | 1981-04-14 | Eaton Corporation | Method for conducting heat to or from an article being treated under vacuum |
| US4514636A (en) * | 1979-09-14 | 1985-04-30 | Eaton Corporation | Ion treatment apparatus |
| US4680061A (en) * | 1979-12-21 | 1987-07-14 | Varian Associates, Inc. | Method of thermal treatment of a wafer in an evacuated environment |
| US4743570A (en) * | 1979-12-21 | 1988-05-10 | Varian Associates, Inc. | Method of thermal treatment of a wafer in an evacuated environment |
| US4909314A (en) * | 1979-12-21 | 1990-03-20 | Varian Associates, Inc. | Apparatus for thermal treatment of a wafer in an evacuated environment |
| FR2490873A1 (en) * | 1980-09-24 | 1982-03-26 | Varian Associates | METHOD AND DEVICE FOR PRODUCING IMPROVED NEUTRALIZATION OF POSITIVE ION BEAM |
| US4463255A (en) * | 1980-09-24 | 1984-07-31 | Varian Associates, Inc. | Apparatus for enhanced neutralization of positively charged ion beam |
| JPS57174467A (en) * | 1981-04-20 | 1982-10-27 | Inoue Japax Res Inc | Ion working device |
| US4475045A (en) * | 1982-05-24 | 1984-10-02 | Varian Associates, Inc. | Rapid pumpdown for high vacuum processing |
| US4847504A (en) * | 1983-08-15 | 1989-07-11 | Applied Materials, Inc. | Apparatus and methods for ion implantation |
| US4786814A (en) * | 1983-09-16 | 1988-11-22 | General Electric Company | Method of reducing electrostatic charge on ion-implanted devices |
| US4595837A (en) * | 1983-09-16 | 1986-06-17 | Rca Corporation | Method for preventing arcing in a device during ion-implantation |
| US4675530A (en) * | 1985-07-11 | 1987-06-23 | Eaton Corporation | Charge density detector for beam implantation |
| JPS62103951A (en) * | 1985-10-29 | 1987-05-14 | Toshiba Corp | Ion implanting apparatus |
| US4804852A (en) * | 1987-01-29 | 1989-02-14 | Eaton Corporation | Treating work pieces with electro-magnetically scanned ion beams |
| JPH01220350A (en) * | 1988-02-26 | 1989-09-04 | Hitachi Ltd | Electrification suppression and particle beam radiating device using its device |
| US4943728A (en) * | 1989-02-28 | 1990-07-24 | Eaton Corporation | Beam pattern control system for an ion implanter |
| US5136171A (en) * | 1990-03-02 | 1992-08-04 | Varian Associates, Inc. | Charge neutralization apparatus for ion implantation system |
| US5113074A (en) * | 1991-01-29 | 1992-05-12 | Eaton Corporation | Ion beam potential detection probe |
| US5466929A (en) * | 1992-02-21 | 1995-11-14 | Hitachi, Ltd. | Apparatus and method for suppressing electrification of sample in charged beam irradiation apparatus |
| US5319212A (en) * | 1992-10-07 | 1994-06-07 | Genus, Inc. | Method of monitoring ion beam current in ion implantation apparatus for use in manufacturing semiconductors |
| US5475231A (en) * | 1993-09-21 | 1995-12-12 | Honeywell Inc. | Apparatus for monitoring ion beams with an electrically isolated aperture |
| US5629528A (en) | 1996-01-16 | 1997-05-13 | Varian Associates, Inc. | Charged particle beam system having beam-defining slit formed by rotating cyclinders |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3071686A (en) * | 1960-02-09 | 1963-01-01 | George J Hanggi | Method and apparatus for low temperature analysis |
| JPS491058B1 (en) * | 1969-09-24 | 1974-01-11 | ||
| US4013891A (en) * | 1975-12-15 | 1977-03-22 | Ibm Corporation | Method for varying the diameter of a beam of charged particles |
-
1977
- 1977-05-05 US US05/794,275 patent/US4118630A/en not_active Expired - Lifetime
-
1978
- 1978-03-20 JP JP53031164A patent/JPS5842939B2/en not_active Expired
- 1978-03-22 CA CA299,581A patent/CA1088218A/en not_active Expired
- 1978-04-13 AU AU35080/78A patent/AU516164B2/en not_active Expired
- 1978-04-27 SE SE7804844A patent/SE424679B/en not_active IP Right Cessation
- 1978-05-05 BR BR787802843A patent/BR7802843A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| SE424679B (en) | 1982-08-02 |
| JPS5842939B2 (en) | 1983-09-22 |
| JPS53136799A (en) | 1978-11-29 |
| SE7804844L (en) | 1978-11-06 |
| US4118630A (en) | 1978-10-03 |
| BR7802843A (en) | 1979-01-16 |
| AU516164B2 (en) | 1981-05-21 |
| AU3508078A (en) | 1979-10-18 |
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