In-vacuum high speed pre-chill and post-heat stations

• US 9,236,216 B2
• Filed: 08/03/2012
• Issued: 01/12/2016
• Est. Priority Date: 08/03/2012
• Status: Active Grant

• Current Assignee: Axcelis Technologies Incorporated
• Original Assignee: Axcelis Technologies Incorporated
• Inventors: Lee, William D., Reynolds, William P., Stone, Stanley W.
• Primary Examiner(s): Berman, Jack
• Assistant Examiner(s): CHOI, JAMES J
• Application Number:
  US13/566,013
• Publication Number:
  US 20140034846A1
• Time in Patent Office: 1,257 Days
• Field of Search: 250/492.3, 279/106
• US Class Current: 1/1
• CPC Class Codes: H01J 2237/2001 Maintaining constant desired temperature
• CPC Class Codes: H01J 2237/2002 Controlling environment of sample
• CPC Class Codes: H01J 2237/2007 Holding mechanisms
• CPC Class Codes: H01J 2237/201 for mounting multiple objects
• CPC Class Codes: H01J 2237/204 Means for introducing and/or outputting objects locks H01J2237/184
• CPC Class Codes: H01J 2237/31705 Impurity or contaminant control
• CPC Class Codes: H01J 37/18 Vacuum locks ; Means for obtaining or maintaining the desired pressure within the vessel vacuum locks for electron-beam tubes in general H01J29/865
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the objects or the material; Means for adjusting diaphragms or lenses associated with the support introducing the objects H01J37/18
• CPC Class Codes: H01J 37/3171 for ion implantation plasma immersion ion implantation H01J37/32412
• CPC Class Codes: H01L 21/02002 Preparing wafers
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/67201 characterized by the construction of the load-lock chamber
• CPC Class Codes: H01L 21/67213 comprising at least one ion or electron beam chamber coating by ion implantation C23C; ion or electron beam tubes H01J37/00
• CPC Class Codes: H01L 21/67742 Mechanical parts of transfer devices robots in general in B25J
• CPC Class Codes: H01L 21/67766 Mechanical parts of transfer devices robots in general in B25J

Abstract

An ion implantation system provides ions to a workpiece positioned in a vacuum environment of a process chamber on a cooled chuck. A pre-chill station within the process chamber has a chilled workpiece support configured to cool the workpiece to a first temperature, and a post-heat station within the process chamber, has a heated workpiece support configured to heat the workpiece to a second temperature. The first temperature is lower than a process temperature, and the second temperature is greater than an external temperature. A workpiece transfer arm is further configured to concurrently transfer two or more workpieces between two or more of the chuck, a load lock chamber, the pre-chill station, and the post-heat station.

Claims

1. An ion implantation system, comprising:

a process chamber having a process environment associated therewith that is substantially evacuated;

an ion implantation apparatus configured to provide a plurality of ions to a workpiece positioned in the process chamber;

a chuck configured to support the workpiece within the process chamber during an exposure of the workpiece to the plurality of ions, wherein the chuck is configured to cool the workpiece to a processing temperature;

a load lock chamber operably coupled to the process chamber, wherein the load lock chamber is configured to isolate the process environment from an external environment, and wherein the load lock chamber comprises a workpiece support configured to support the workpiece during a transfer of the workpiece between the process chamber and external environment; and

a pre-chill station positioned within the process chamber, wherein the pre-chill station comprises a chilled workpiece support that is separate from the chuck and is configured to cool the workpiece to a first temperature;

a chilled workpiece holding station positioned within the process chamber, wherein the chilled workpiece holding station comprises a cold workpiece support configured to receive and support the workpiece transferred thereto from the pre-chill station, and wherein the cold workpiece support is further configured to maintain the first temperature of the workpiece while the workpiece resides thereon;

a post-heat station positioned within the process chamber and in continuous fluid communication with the process environment, wherein the post-heat station comprises a heated workpiece support configured to heat the workpiece to a second temperature;

a heated workpiece holding station positioned within the process chamber, wherein the heated workpiece holding station comprises a hot workpiece support configured to receive and support the workpiece transferred thereto from the post-heat station, and wherein the hot workpiece support is further configured to maintain the second temperature of the workpiece while the workpiece resides thereon; and

a workpiece transfer arm, wherein the workpiece transfer arm is configured to concurrently transfer two or more workpieces between two or more of the chuck, load lock chamber, chilled workpiece holding station, heated workpiece holding station, pre-chill station, and post-heat station.

2. The ion implantation system of claim 1, wherein the chuck comprises an electrostatic chuck configured to cool the workpiece to the processing temperature.

3. The ion implantation system of claim 1, wherein the workpiece transfer arm is configured to concurrently grasp or release a respective workpiece from the chuck and load lock chamber, the chilled workpiece holding station and heated workpiece holding station, or the pre-chill station and post-heat station, based on a rotational position of the workpiece transfer arm.

4. The ion implantation system of claim 1, wherein the first temperature is lower than the process temperature.

5. The ion implantation system of claim 1, wherein the pre-chill station comprises a cooling plate configured to support the workpiece and to cool the workpiece to the first temperature, and wherein the workpiece transfer arm is configured to transfer the workpiece to and from the cooling plate.

6. The ion implantation system of claim 5, wherein the cooling plate comprises one or more of a peltier cooler, an expansion chamber, a cryogenic head, and a circulatory refrigeration loop.

7. The ion implantation system of claim 5, wherein the pre-chill station further comprises:

a pre-chill gas sealing ring disposed about a perimeter of the chilled workpiece support, wherein the pre-chill gas sealing ring is configured to support a periphery of the workpiece;

a pre-chill clamp configured to maintain a position of the workpiece on the chilled workpiece support; and

a pre-chill gas source configured to provide a pre-chill gas between a gas cooling space defined between the workpiece and a surface of the chilled workpiece support, wherein a pressure of the pre-chill gas generally determines a cooling of the workpiece.

8. The ion implantation system of claim 1, wherein the post-heat station comprises a heating station support comprising a heating plate configured to support the workpiece and to heat the workpiece to the second temperature, and wherein the workpiece transfer arm is configured to transfer the workpiece to and from the heating plate.

9. The ion implantation system of claim 8, wherein the post-heat station further comprises:

a post-heat gas sealing ring disposed about a perimeter of the heated workpiece support, wherein the post-heat gas sealing ring is configured to support a periphery of the workpiece;

a post-heat clamp configured to maintain a position of the workpiece on the heated workpiece support; and

a post-heat gas source configured to provide a post-heat gas between a gas heating space defined between the workpiece and a surface of the heated workpiece support, wherein a pressure of the post-heat gas generally determines a heating of the workpiece.

10. The ion implantation system of claim 1, wherein the chuck is diametrically opposed to the load lock chamber, the pre-chill station is diametrically opposed to the post-heat station, and the chilled workpiece holding station is diametrically opposed to the heated workpiece holding station within the process chamber.

11. The ion implantation system of claim 10, wherein the workpiece transfer arm comprises two pairs of workpiece transfer clamps positioned approximately 90 degrees from one another, wherein each pair of workpiece transfer clamps is diametrically opposed to each other, and wherein each pair of workpiece transfer clamps is configured to respectively concurrently grasp or release a respective workpiece from the chuck and load lock chamber, from the pre-chill station and post-heat station, or from the chilled workpiece holding station and heated workpiece holding station, based on a rotational position of the workpiece transfer arm.

12. The ion implantation system of claim 1, wherein the chuck is diametrically opposed to the load lock chamber, and the pre-chill station is diametrically opposed to the post-heat station within the process chamber.

13. The ion implantation system of claim 1, wherein the workpiece transfer arm comprises at least one pair of workpiece transfer clamps configured to individually rotate about an axis, wherein the at least one pair of workpiece transfer clamps are configured to concurrently grasp or release a respective workpiece from the chuck and load lock chamber, from the chilled workpiece holding station and heated workpiece holding station, or from the pre-chill station and post-heat station, based on a rotational position of the at least one pair of workpiece transfer clamps.

14. The ion implantation system of claim 1, wherein the post-heat station and pre-chill station are generally isolated from one another within the process chamber.

15. The ion implantation system of claim 1, further comprising a controller configured to determine the first temperature and the second temperature, based, at least in part, on a desired process throughput.

16. The ion implantation system of claim 15, further comprising a temperature monitoring system configured to measure a temperature of the workpiece at the pre-chill station and the post-heat station, wherein the controller is further configured to control cooling of the workpiece to the first temperature and the heating of the workpiece to the second temperature, based, at least in part, on the measured temperature of the workpiece.

24. The ion implantation system of claim 1, wherein the workpiece transfer arm is further configured to concurrently grasp and release two workpieces disposed at respective diametrically opposed ends of the workpiece transfer arm, and wherein the workpiece transfer arm comprises two arms configured to selectively rotate in unison about an axis and to selectively open and close in a scissor-like manner by individually rotating about the axis, wherein in an open position, the two arms are configured to generally surround, but not contact the two workpieces, and wherein in a closed position, the two arms are configured to contact and concurrently grip the two workpieces.

17. A method for implanting ions into a workpiece at sub-ambient temperatures, the method comprising:

providing a workpiece in an external environment at an external temperature and external pressure;

providing a workpiece transfer arm comprising at least one pair of workpiece transfer clamps that are diametrically opposed to each other and configured to open and close in a scissor-like manner, therein being configured to selectively grip and release a periphery of two or more workpieces;

transferring the workpiece from the external environment to a load lock chamber;

lowering the pressure within the load lock chamber to a substantial vacuum;

transferring the workpiece from the load lock chamber to pre-chill station within a vacuum environment of a process chamber in a cold implant ion implantation system via the workpiece transfer arm;

cooling the workpiece at the pre-chill station, wherein the pre-chill station is cooled to a first temperature that is lower than a process temperature;

transferring the workpiece from the pre-chill station to a cold workpiece support in a chilled workpiece holding station within the vacuum environment via the workpiece transfer arm;

maintaining the first temperature of the workpiece via the cold workpiece support while the workpiece resides on the cold workpiece support;

transferring the workpiece from the pre-chill chilled workpiece holding station to a chuck that is cooled to the process temperature within in the vacuum environment via the workpiece transfer arm;

implanting ions into the workpiece;

transferring the workpiece from the chuck to a post-heat station within the vacuum environment via the workpiece transfer arm;

heating the workpiece at the post-heat station, wherein the post-heat station is heated to a second temperature that is greater than the external temperature;

transferring the workpiece from the post-heat station to a hot workpiece support in a heated workpiece holding station within the vacuum environment via the workpiece transfer arm;

maintaining the second temperature of the workpiece via the hot workpiece support while the workpiece resides on the hot workpiece support;

transferring the workpiece from the post h at heated workpiece holding station to the load lock chamber via the workpiece transfer arm;

increasing the pressure within the load lock chamber to the external pressure; and

removing the workpiece from the load lock chamber.

18. The method of claim 17, wherein cooling the workpiece at the pre-chill station comprises clamping the workpiece to a chilled workpiece support and providing a backside gas at the first temperature to a backside of the workpiece.

19. The method of claim 17, wherein heating the workpiece at the post-heat station comprises clamping the workpiece to a heated workpiece support and providing a backside gas at the second temperature to a backside of the workpiece.

20. The method of claim 17, wherein the first temperature is at least an order of magnitude lower than the process temperature and the second temperature is not more than approximately 150 C.

21. The method of claim 17, wherein transferring the workpiece from the load lock chamber to the pre-chill station occurs while concurrently transferring a second workpiece from the chuck to the post-heat station.

22. The method of claim 21, wherein transferring the workpiece from the pre-chill station to the chuck occurs while concurrently transferring the second workpiece from the post-heat station to the load lock chamber.

23. The method of claim 17, wherein transferring the workpiece comprises concurrently transferring two or more-workpieces.