In situ removal of contaminants from the interior surfaces of an ion beam implanter

• US 5,554,854 A
• Filed: 07/17/1995
• Issued: 09/10/1996
• Est. Priority Date: 07/17/1995
• Status: Expired due to Term

• Current Assignee: Axcelis Technologies Incorporated
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Blake, Julian G.
• Primary Examiner(s): Berman, Jack I.
• Assistant Examiner(s): NGUYEN, KIET TUAN
• Application Number:
  US08/503,299
• Time in Patent Office: 421 Days
• Field of Search: 250/492.21, 250/492.2, 250/398
• US Class Current: 250/492.21
• CPC Class Codes: H01J 2237/0041 Neutralising arrangements
• CPC Class Codes: H01J 2237/022 Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube
• CPC Class Codes: H01J 2237/31701 Ion implantation
• CPC Class Codes: H01J 37/3002 Details

Abstract

An in situ method of removing contaminant material adhering to interior surfaces of an ion beam implanter is disclosed. The method includes the steps of: extracting ions from source materials and forming the ions into an ion beam that traverses a beam path through an evacuated region to an ion implantation chamber; providing a control means for controlling a trajectory of the ion beam within the evacuated region; utilizing the control means to direct the ion beam to strike interior surfaces of the ion beam implanter in contact with the evacuated region to dislodge the contaminant material; and removing the contaminant material from the evacuated region of the implanter.

Claims

1. A method for removing contaminant material adhering to interior surfaces of an ion beam implanter, the method comprising the steps of:

a) extracting ions from source materials and forming the ions into an ion beam that traverses a beam path through an evacuated region along a trajectory to an ion implantation chamber;

b) adjusting the trajectory of the ion beam to cause the ion beam to strike interior surfaces of the implanter in contact with the evacuated region to dislodge the contaminant material from the interior surfaces; and

c) removing the dislodged contaminant material from the evacuated region of the implanter.

2. The method of removing contaminant material set forth in claim 1 wherein the ion beam implanter includes a mass analyzing magnet generating a magnetic field through which the ion beam passes, and wherein the adjusting step comprises the step of altering a direction of the ion beam as the beam passes through the magnetic field to direct the ion beam to strike the interior surfaces of the implanter.

3. The method of removing contaminant material set forth in claim 2 further comprising the step of tuning of the mass analyzing magnet to direct the ion beam to strike the interior surfaces, wherein the step of tuning includes the step of varying the tuning of the mass analyzing magnet in a selected repetitive pattern such that the ion beam repetitively sweeps across an area of the interior surfaces to be cleaned.

4. The method of dislodging deposited contaminant material set forth in claim 3 including the additional step of selectively energizing an ion beam neutralization apparatus surrounding a portion of the path of travel so as to increase an area of the interior surfaces to be cleaned.

5. The method of removing contaminant material set forth in claim 1 wherein the ion beam implanter includes a set of electrodes disposed around a portion of the ion beam path and the step of adjusting is performed by adjustably energizing at least one electrode to alter a direction of the ion beam as it passes through the electrodes to cause the ion beam to strike the interior surfaces of the ion beam implanter.

6. The method of removing contaminant material set forth in claim 5 further comprising the step of adjusting a level of energization of at least one electrode in the set of electrodes to direct the ion beam to strike the interior surfaces, wherein the step of adjusting the level includes the step of varying the level of energization in the at least one electrode a selected repetitive pattern such that the ion beam repetitively sweeps across an area of the interior surfaces to be cleaned.

7. The method for removing contaminant material set forth in claim 1 wherein the source materials include at least one of oxygen gas, hydrogen gas and fluorine gas.

8. The method for removing contaminant material set forth in claim 1 wherein the contaminant material comprises a boron isotope and the source materials include at least one of oxygen gas and hydrogen gas.

9. The method for removing contaminant material set forth in claim 1 wherein the contaminant material comprises photoresist material and the source materials include fluorine gas.

10. The method for removing contaminant material set forth in claim 1 where the ion beam implanter includes an ion beam neutralizer through which the beam path passes that is selectively actuated to cause divergence of the ion beam and selectively actuated to generate electron emissions to neutralize the ion beam and wherein the step of adjusting the trajectory is performed by directing the ion beam to strike the interior surfaces by causing divergence of the ion beam.

11. The method of removing contaminant material set forth in claim 1 wherein the ions extracted from the source material chemically bond with the contaminant material as the contaminant material is dislodged,

12. The method of removing contaminant material set forth in claim 1 wherein the step of directing the ion beam to strike the interior surfaces includes the step of increasing beam divergence to increase an area struck by the beam.

13. A method of dislodging deposited contaminant material from interior surfaces of an ion beam implanter, the method comprising the step of adjusting a magnetic field strength of a mass analyzing magnet through which ions moving along a path of travel from an ion source to an implantation station to deflect the ions along paths that cause ions to strike the interior surfaces thereby dislodging the deposited contaminant material.

14. The method of dislodging deposited contaminant material set forth in claim 13 wherein the magnetic field strength is varied in a repetitive pattern causing the ions to repetitively sweep across an area of the interior surfaces to be cleaned.

15. The method of dislodging deposited contaminant material set forth in claim 13 wherein the ions striking the interior surfaces create volatile species of the contaminant material as the contaminant material is dislodged.

16. The method of dislodging deposited contaminant material set forth in claim 13 wherein the mass analyzing magnet includes field windings and the magnetic field strength of the mass analyzing magnet is adjusted by changing a current flow through the field windings,

17. The method of dislodging deposited contaminant material set forth in claim 13 wherein the method includes the additional step of removing the dislodged contaminant material from the implanter.

18. The method of dislodging deposited contaminant material set forth in claim 13 wherein the contaminant material comprises photoresist material and the ions are generated from source materials including fluorine gas.

19. The method of dislodging deposited contaminant material set forth in claim 13 wherein the ions moving along the deflected paths of travel are subjected to an electric field which increases a divergence of the paths of travel of the ions.

20. An ion implanter for treating a workpiece comprising:

a) an ion source for providing ions and for emitting said ions from a source chamber having one or more ion exit apertures;

b) electrode structure positioned in relation to the one or more ion exit apertures of the source chamber for causing ions exiting the source chamber to form an ion beam;

c) ion beam defining structure bounding an evacuated region that defines an ion beam travel path from the electrode structure;

d) an ion implantation chamber including structure for supporting a workpiece that intercepts the ions entering the implantation chamber after traversing the beam travel path from the source to the implantation chamber;

e) a material source for introducing ionization materials into the ion source chamber which are ionized and leave the source chamber to chemically interact with contaminants that contact the structure bounding the evaluated region of the ion beam implanter during ion beam treatment of workpieces placed within the ion implantation chamber;

f) an implantation controller for controlling ion beam movement through the evacuated region from the source to the implantation chamber; and

g) a pump for removing dislodged contaminant material from the evacuated region of the ion implanter.

21. The apparatus of claim 20 wherein the ion source introduces a material that chemically interacts with the contaminants.

22. The apparatus of claim 20 wherein the ion source comprises a chamber for providing multiple beam portions which combine to form a ribbon beam that traverses a travel path to the ion implantation chamber and wherein the workpiece comprises a flat panel having a width less than the width of the ribbon beam and additionally comprising means for moving the flat panel back and forth through the ribbon beam.

23. A method for removing contaminant material adhering to interior surfaces of an ion beam implanter, the method comprising the steps of:

a) extracting ions from source materials that combine with contaminant materials to form compounds made up of constituents of the ion source material and the contaminant materials;

b) forming the ions into an ion beam that traverses a beam path through an evacuated region along a trajectory to an ion implantation chamber;

c) controlling the ion beam to cause the ion beam to strike interior surfaces of the implanter in contact with the evacuated region to dislodge the contaminant material from the interior surfaces and form said compounds; and

c) removing the compounds from the evacuated region of the implanter.

24. Apparatus for removing contaminant material adhering to interior surfaces of an ion beam implanter comprising:

a) means for extracting ions from source materials and forming the ions into an ion beam that traverses a beam path through an evacuated region along a trajectory to an ion implantation chamber;

b) means for adjusting the trajectory of the ion beam to cause the ion beam to strike interior surfaces of the implanter in contact with the evacuated region to dislodge the contaminant material from the interior surfaces; and

c) means for removing dislodged contaminant material from the evacuated region of the implanter.

25. The apparatus for removing contaminant material set forth in claim 24 wherein the ion beam implanter includes a mass analyzing magnet generating a magnetic field through which the ion beam passes, and wherein the means for adjusting comprises means for altering a direction of the ion beam as the beam passes through the magnetic field to direct the ion beam to strike the interior surfaces of the implanter.

26. The apparatus for removing contaminant material set forth in claim 25 wherein the means for adjusting controls the mass analyzing magnet to direct the ion beam to strike the interior surfaces includes means for varying the tuning of the mass analyzing magnet in a selected repetitive pattern such that the ion beam repetitively sweeps across an area of the interior surfaces to be cleaned.

27. The apparatus for removing contaminant material set forth in claim 24 wherein the ion beam implanter includes a set of electrodes disposed around a portion of the ion beam path and wherein the means for adjusting means for adjustably energizing at least one electrode to alter the direction of the ion beam as it passes through the electrodes to cause the ion beam to strike the interior surfaces of the ion beam implanter.

28. The apparatus for removing contaminant material set forth in claim 27 comprising means for adjusting a level of energization of at least one electrode in the set of electrodes to direct the ion beam to strike the interior surfaces by varying the level of energization in the at least one electrode in a selected repetitive pattern such that the ion beam repetitively sweeps across an area of the ion implanter interior surfaces to be cleaned.

29. The apparatus of claim 24 wherein the source materials include at least one of oxygen gas, hydrogen gas and fluorine gas.

30. The apparatus of claim 24 wherein the contaminant material comprises a boron isotope and the source materials include at least one of oxygen gas and hydrogen gas.

31. The apparatus of claim 24 wherein the contaminant material comprises photoresist material and the source materials include fluorine gas.

32. The apparatus of claim 24 where the means for adjusting comprises an ion beam neutralizer through which the beam path passes that is selectively actuated to cause divergence of the ion beam and selectively actuated to generate electron emissions to neutralize the ion beam and wherein the step of adjusting the trajectory is performed by directing the ion beam to strike the interior surfaces by causing divergence of the ion beam.

33. The apparatus of claim 24 wherein the means for adjusting comprises means to increase beam divergence to increase a surface area of the implanter that is struck by the beam.

34. An ion implanter for treating a workpiece comprising:

a) an ion source for providing ions and for emitting said ions from a source chamber for ion treatment of a workpiece;

b) an ion implantation chamber having a support for a workpiece placed within the ion implantation chamber that intercepts the ions entering the implantation chamber after said ions traverse a beam travel path from the source to the implantation chamber;

c) ion beam defining structure bounding an evacuated region that defines the ion beam travel path from the ion source to the ion implantation chamber;

d) an implantation controller for controlling ion beam movement through the evacuated region from the ion source to the implantation chamber;

e) means for removing contaminant material from an evacuated region of the ion implantation chamber; and

f) structure for in-situ removal of contaminants from the evacuated region within the ion implantation chamber comprising;

i) first and second conductive electrodes in contact with the evacuated region of the ion implantation chamber wherein one conductive electrode of said first and second conductive electrodes is positioned to promote formation of an ion plasma within the implantation chamber wherein ions in the plasma combine with contaminants at a region in close proximity to said one conductive electrode; and

ii) biasing means for applying an electric potential between the first and second conductive electrodes to maintain the ion plasma in a region of the one conductive electrode.

35. The ion implanter of claim 34 wherein the first conductive electrode comprises the workpiece support wherein the ion implantation chamber comprises conductive inner walls and the second conductive electrode comprises a conductive electrode electrically isolated from the conductive inner walls bounding the evacuated region of the ion implantation chamber.

36. The ion implanter of claim 34 wherein the ion implantation chamber comprises conductive inner walls and the first conductive electrode is an electrode that is electrically isolated from the conductive inner walls of the ion implantation chamber and the second metallic member comprises said conductive inner walls.