Pinched plasma bridge flood gun for substrate charge neutralization

• US 9,070,538 B2
• Filed: 12/20/2013
• Issued: 06/30/2015
• Est. Priority Date: 10/25/2013
• Status: Active Grant

• Current Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Original Assignee: Varian Semiconductor Equipment Associates Incorporated (Applied Materials Incorporated)
• Inventors: Shajii, Ali, Sonnenshein, David, Kishinevsky, Michael, Cowe, Andrew B., Stratoti, Gregory E.
• Primary Examiner(s): Vanore, David A
• Application Number:
  US14/137,196
• Publication Number:
  US 20150115796A1
• Time in Patent Office: 557 Days
• Field of Search: 250/492.21, 250/423.R, 250/288, 250/423.F, 250/424, 250/492.2, 438/513, 438/514, 438/495, 438/506, 438/508
• US Class Current: 1/1
• CPC Class Codes: C23C 14/48 Ion implantation
• CPC Class Codes: H01J 2237/0041 Neutralising arrangements
• CPC Class Codes: H01J 2237/0044 of objects being observed or treated
• CPC Class Codes: H01J 2237/327 Arrangements for generating the plasma
• CPC Class Codes: H01J 2237/3365 Plasma source implantation
• CPC Class Codes: H01J 37/08 Ion sources; Ion guns
• CPC Class Codes: H01J 37/3171 for ion implantation
• CPC Class Codes: H01J 37/32174 Circuits specially adapted for controlling the RF discharge
• CPC Class Codes: H01J 37/32357 Generation remote from the workpiece, e.g. down-stream
• CPC Class Codes: H01J 37/32412 Plasma immersion ion implantation
• CPC Class Codes: H01J 37/32422 Arrangement for selecting ions or species in the plasma
• CPC Class Codes: H01J 37/32623 Mechanical discharge control means
• 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

Abstract

A plasma flood gun for an ion implantation system includes an insulating block portion and first and second conductive block portions disposed on opposite sides of the insulating block portion. Conductive straps can be coupled between the first and second conductive block portions. The conductive block portions and the central body portion include recesses which form a closed loop plasma chamber. A power source is coupled to the conductive block portions for inductively coupling radio frequency electrical power into the closed loop plasma chamber to excite the gaseous substance to generate a plasma. The respective recess in the second conductive block portion includes a pinch region having a cross-sectional dimension that is smaller than a cross-sectional area of portion of the closed loop plasma chamber directly adjacent the pinch region. The pinch region can be positioned immediately adjacent an outlet portion formed in the second conductive block portion.

Claims

1. A plasma flood gun for use in ion implantation system, the plasma flood gun comprising:

an insulating block portion having a base portion and a central body portion;

first and second conductive block portions disposed on the base portion and opposite sides of the central body portion; and

a conductive strap coupling the first conductive block portion to the second conductive block portion;

the first and second conductive block portions and the central body portion including respective recesses formed therein which form a closed loop plasma chamber, wherein the first and second conductive block portions receive radio frequency (RF) electrical power to generate a plasma within the closed loop plasma chamber by exciting a gaseous substance; and

wherein the respective recess in the second conductive block portion includes a pinch region having a cross-sectional dimension that is smaller than a cross-sectional dimension of a portion of the closed loop plasma chamber directly adjacent the pinch region, the pinch region positioned immediately adjacent an outlet portion having an outlet aperture.

2. The plasma flood gun according to claim 1, the closed loop plasma chamber comprising first and second portions, the first portion oriented parallel to the base portion of the insulating block portion, the second portion oriented perpendicular to the first portion.

3. The plasma flood gun according to claim 1, the pinch region disposed in the second portion of the closed loop plasma chamber.

4. The plasma flood gun according to claim 3, further comprising a housing with a housing aperture, the outlet portion comprising an aperture plate disposed within the housing aperture.

5. The plasma flood gun according to claim 1, the first portion of the closed loop plasma chamber comprising a U-shape.

6. The plasma flood gun according to claim 1, the second portion of the closed loop plasma chamber comprising a pair of legs which converge at the pinch region.

7. The plasma flood gun according to claim 1, wherein the gaseous substance comprises argon, krypton, xenon, or a mixture thereof.

8. The plasma flood gun according to claim 1, the closed loop plasma chamber interoperative with a power source supplying the RF electrical power to generate the plasma over a pressure range of 1-100 mTorr.

9. The plasma flood gun according to claim 1, comprising a bias source coupled to the first or second conductive block and configured to adjust electron emission from the plasma flood gun by adjusting voltage of the plasma flood gun with respect to ground.

10. The plasma flood gun according to claim 1, wherein the RF electrical power operates at a frequency of 13.56 MHz.

11. A plasma loop assembly for a plasma flood gun in ion implantation system, the plasma loop assembly comprising:

an insulating block portion, and first and second conductive block portions disposed on opposite sides of the insulating block portion, the first and second conductive block portions and the insulating block portion having respective recesses forming a closed loop plasma chamber; and

a conductive strap coupled between the first and second conductive block portions;

wherein the first and second conductive block portions receive radio frequency (RF) electrical power to generate a plasma within the closed loop plasma chamber by exciting a gaseous substance;

wherein the respective recess in the second conductive block portion includes a pinch region positioned immediately adjacent an outlet aperture, the pinch region configured to allow easy transport of the plasma through the outlet aperture, which is sized to allow charged particles of the plasma to flow therethrough.

12. The plasma loop assembly according to claim 11, the closed loop plasma chamber comprising first and second portions, the second portion oriented perpendicular to the first portion.

13. The plasma loop assembly according to claim 11, the pinch region comprising a U-shaped channel adjacent the outlet aperture, the outlet aperture disposed in an aperture plate, the outlet aperture having a conical cross-section.

14. The plasma loop assembly according to claim 11, the pinch region comprising a U-shaped channel adjacent the outlet aperture, the outlet aperture disposed in an aperture plate, the outlet aperture comprising a tapered oval slot.

15. The plasma loop assembly according to claim 11, the first portion of the closed loop plasma chamber comprising a U-shape.

16. The plasma loop assembly according to claim 11, the second portion of the closed loop plasma chamber comprising a pair of legs which converge at the pinch region.

17. The plasma loop assembly according to claim 11, the closed loop plasma chamber interoperative with a power source supplying the RF electrical power to generate the plasma over a pressure range of 1-100 mTorr.

18. A plasma loop assembly for materials processing applications, the plasma loop assembly comprising:

an insulating block portion, and first and second conductive block portions disposed on opposite sides of the insulating block portion, the first and second conductive block portions and the insulating block portion having respective recesses forming a closed loop plasma chamber, the respective recess in the second conductive block portion including an outlet aperture sized to allow charged particles of the plasma to flow therethrough; and

a conductive strap coupling the first conductive block portion to the second conductive block portions;

wherein the first and second conductive block portions receive radio frequency (RF) electrical power to generate a plasma within the closed loop plasma chamber by exciting a gaseous substance; and

wherein the respective recess in at least one of the first conductive block portion, the second conductive block portion or the insulating block portion is coupled to an outlet aperture.

19. The plasma loop assembly according to claim 18, the closed loop plasma chamber comprising first and second portions, the second portion oriented perpendicular to the first portion.

20. The plasma loop assembly according to claim 18, further comprising a pinch region positioned immediately adjacent the outlet aperture, the pinch region configured permit a maximum flow of plasma toward the outlet aperture.

21. The plasma loop assembly according to claim 20 the second portion of the closed loop plasma chamber comprising a pair of legs which converge at the pinch region.

22. The plasma loop assembly according to claim 18, the closed loop plasma chamber interoperative with a power source supplying the RF electrical power to generate the plasma over a pressure range of 1-100 mTorr.

23. The plasma loop assembly according to claim 18, wherein a power source supplying the RF electrical power is coupled to the first and second conductive block portions via the conductive strap.