Vapor Compression Refridgeration Chuck for Ion Implanters

• US 20100171044A1
• Filed: 03/17/2010
• Published: 07/08/2010
• Est. Priority Date: 04/30/2008
• Status: Active Grant

• Current Assignee: Axcelis Technologies Incorporated
• Original Assignee: Axcelis Technologies Incorporated
• Inventors: Lee, William D., LaFontaine, Marvin R., Purohit, Ashwin M.
• Granted Patent: US 9,558,980 B2
• Time in Patent Office: Days
• US Class Current: 250/491.100
• CPC Class Codes: H01J 2237/002 Cooling arrangements
• CPC Class Codes: H01J 2237/2001 Maintaining constant desired temperature
• CPC Class Codes: H01J 2237/2007 Holding mechanisms
• CPC Class Codes: H01J 2237/20214 Rotation
• CPC Class Codes: H01J 2237/2065 Temperature variations
• CPC Class Codes: H01J 2237/31701 Ion implantation
• CPC Class Codes: H01J 37/20 Means for supporting or positioning the object or the material; Means for adjusting diaphragms or lenses associated with the support
• CPC Class Codes: H01J 37/3171 for ion implantation
• CPC Class Codes: H01L 21/67109 mainly by convection
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

Aspects of the present invention relate to ion implantation systems that make use of a vapor compression cooling system. In one embodiment, a thermal controller in the vapor compression system sends refrigeration fluid though a compressor and a condenser according to an ideal vapor compression cycle to help limit or prevent undesired heating of a workpiece during implantation, or to actively cool the workpiece.

Claims

1. An ion implantation system, comprising:

a scan arm extending in a radial direction between a pivot point and a distal end, wherein a gas supply conduit and a separate refrigerant supply conduit both extend from near the pivot point of the scan arm towards the distal end of the scan arm; and

an electrostatic chuck coupled proximate to the distal end of the scan arm, the electrostatic chuck comprising;

an engagement region adapted to selectively engage a workpiece, and one or more cooling channels in fluid communication with the refrigerant supply conduit;

wherein the engagement region and workpiece, when engaged, cooperatively define a cavity therebetween, wherein the cavity is in fluid communication with the gas supply conduit and is fluidly isolated from the one or more cooling channels.

2. The ion implantation system of claim 1, wherein the electrostatic chuck further comprises:

a flow restrictor between the refrigerant supply conduit and the one or more cooling channels, where the flow restrictor comprises a central region having sidewalls separated by a first distance and distal regions having sidewalls separated by a second distance that is greater than the first distance.

3. The ion implantation system of claim 1, wherein the scan arm is configured to translate the workpiece on a first axis while the ion beam is scanned on a second axis that is perpendicular to the first axis.

4. The ion implantation system of claim 1, wherein the scan arm is configured to move back and forth in a pendulum-like manner about the pivot point.

5. The ion implantation system of claim 4, wherein an axial hub couples the electrostatic chuck proximate to the distal end of the scan arm, and wherein the axial hub is configured to rotate the electrostatic chuck so the workpiece rotates about the axial hub while the scan arm is moving in the pendulum-like manner.

6. The ion implantation system of claim 1, wherein the engagement region comprises:

a central region having one or more gas supply orifices; and

an annulus region generally disposed about a periphery of the central region;

wherein the central region is recessed with respect to the annulus region so as to form the cavity between the surface of the electrostatic chuck and the workpiece, when engaged.

7. An ion implantation system, comprising:

a scan arm extending in a radial direction between a pivot point and a distal end, wherein a gas supply conduit and a separate refrigerant supply conduit both extend from near the pivot point of the scan arm towards the distal end of the scan arm; and

a first plate associated with the distal end of the scan arm and having an engagement region to which a workpiece is detachably engaged;

wherein the engagement region comprises;

a central region having one or more gas supply orifices, and an annulus region generally disposed about a periphery of the central region, wherein the central region is recessed with respect to the annulus region to define a cavity between the workpiece and the first plate, and wherein the cavity is in fluid communication with the refrigerant supply conduit via the one or more gas supply orifices; and

a second plate positioned between the first plate and the distal end of the scan arm, wherein the second plate comprises one or more cooling channels in fluid communication with the refrigerant supply conduit, the one or more cooling channels fluidly isolated from both the gas supply orifices and the cavity.

8. The ion implantation system of claim 7, wherein the at least one of the first plate or the second plate further comprises a flow restrictor between the refrigerant supply conduit and the one or more cooling channels, where the flow restrictor comprises a central region having sidewalls separated by a first distance and distal regions having sidewalls separated by a second distance that is greater than the first distance.

9. The ion implantation system of claim 7, wherein the scan arm is configured to move back and forth in a pendulum-like manner about the pivot point.

10. The ion implantation system of claim 9, wherein the first and second plates are mounted about an axial hub to the distal end of the scan arm, and wherein the axial hub is configured to rotate the first plate so the workpiece rotates about the axial hub while the scan arm is moving in the pendulum-like manner.

11. The ion implantation system of claim 7, wherein the ion implantation system further comprises:

one or more electrodes configured to be selectively coupled to a clamping voltage potential.

12. The ion implantation system of claim 7, wherein the central region of the first plate is generally planar and void of any structure extending outwardly therefrom.

13. A method for clamping a workpiece, the method comprising:

providing an electrostatic chuck having at least one cooling channel, wherein the electrostatic chuck comprises at least one electrode

providing a cushioning gas via at least one gas supply orifice defined in the central region of the electrostatic chuck at a first gas pressure,

applying a voltage potential to the at least one electrode, therein generally attracting the workpiece to the electrostatic chuck with an attractive force;

controlling the first gas pressure and first voltage potential, wherein the first repelling force and first attractive force are generally equalized; and

providing a fluid to the electrostatic chuck to cool the electrostatic chuck.

14. The method of claim 13, wherein the compressed refrigerant fluid is provided to the electrostatic chuck via a flow restrictor, where the flow restrictor comprises a central region having sidewalls separated by a first distance and distal regions having sidewalls separated by a second distance that is greater than the first distance.