Apparatus including showerhead electrode and heater for plasma processing

• US 20050241765A1
• Filed: 04/30/2004
• Published: 11/03/2005
• Est. Priority Date: 04/30/2004
• Status: Active Grant

• Current Assignee: Lam Research Corporation
• Original Assignee: Lam Research Corporation
• Inventors: Lenz, Eric, Dhindsa, Rajinder
• Granted Patent: US 7,712,434 B2
• Time in Patent Office: Days
• US Class Current: 156/345.340
• CPC Class Codes: H01J 37/32009 Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources plasma generation in general H05H1/24
• CPC Class Codes: H01J 37/32082 Radio frequency generated discharge H01J37/32357, H01J37/32366, H01J37/32394 and H01J37/32403 take precedence
• CPC Class Codes: H01J 37/3244 Gas supply means
• CPC Class Codes: H01J 37/32724 Temperature

Abstract

A plasma processing apparatus includes a heater in thermal contact with a showerhead electrode, and a temperature controlled top plate in thermal contact with the heater to maintain a desired temperature of the showerhead electrode during semiconductor substrate processing. A gas distribution member supplies a process gas and radio frequency (RF) power to the showerhead electrode.

Claims

1. A showerhead electrode assembly, comprising:

a showerhead electrode adapted to be mounted in an interior of a vacuum chamber and supply process gas to a gap between the showerhead electrode and a bottom electrode on which a semiconductor substrate is supported;

a gas distribution member attached to the showerhead electrode;

a thermal path member attached to the gas distribution member; and

a heater attached to the thermal path member;

wherein the heater transmits heat to the showerhead electrode through a thermal path comprising the gas distribution member and the thermal path member.

2. The showerhead electrode assembly of claim 1, wherein the thermal path member comprises a thermally conducting, electrically insulating body.

3. The showerhead electrode assembly of claim 1, wherein the thermal path member comprises a nitride material.

4. The showerhead electrode assembly of claim 1, wherein the thermal path member comprises aluminum nitride or boron nitride.

5. A vacuum chamber comprising the showerhead electrode assembly of claim 1, wherein a first portion of the gas distribution member extends into an opening in the temperature controlled top wall and a second portion of the gas distribution member extends completely over the showerhead electrode.

6. The vacuum chamber comprising the showerhead electrode assembly of claim 5, wherein the temperature controlled top wall of the vacuum chamber withdraws heat from the showerhead electrode via a thermal path passing through the heater, the thermal path member, the gas distribution member and the showerhead electrode.

7. The vacuum chamber comprising the showerhead electrode assembly of claim 5, wherein the showerhead electrode is a RF powered electrode and said gas distribution member is of an electrically conductive material which distributes RF power from the first portion of the gas distribution member to the second portion of the gas distribution member and then to the showerhead electrode.

8. The vacuum chamber comprising the showerhead electrode assembly of claim 7, wherein the gas distribution member contacts 0.1 to 99.9% of the cross sectional area on the backside of the showerhead electrode.

9. The showerhead electrode assembly of claim 1, further comprising a ground electrode surrounding the showerhead electrode, the ground electrode including an exposed surface facing the gap and an insulator is located between an inner periphery of the ground electrode and an outer periphery of the showerhead electrode.

10. A method of controlling plasma etching, comprising:

applying power to a heater in a plasma etching chamber;

heating at least a portion of a showerhead electrode in the plasma etching chamber to a predetermined temperature by conducting heat from the heater to the showerhead electrode;

supplying process gas to the plasma etching chamber through the showerhead electrode, the process gas flowing into a gap between the showerhead electrode and a bottom electrode on which a semiconductor substrate is supported; and

etching a semiconductor substrate in the plasma etching chamber by applying RF power to the showerhead electrode and energizing the process gas into a plasma state, wherein the power applied to the heater and the power applied to the showerhead electrode are electrically isolated from one another by a thermal path member.

11. The method of claim 10, wherein the heating of the showerhead electrode comprises heating and maintaining at least a portion of the showerhead electrode at a temperature of at least 80°

C.

12. The method of claim 10, wherein the heating of the showerhead electrode comprises heating and maintaining at least a portion of the showerhead electrode at a temperature of at least 100°

C.

13. The method of claim 10, wherein the heating of the showerhead electrode comprises heating and maintaining at least a portion of the showerhead electrode at a temperature of at least 150°

C.

14. The method of claim 10, wherein the heating of the showerhead electrode occurs before the etching of the semiconductor substrate.

15. The method of claim 10, wherein the etching comprises etching openings in an oxide layer on the semiconductor substrate, the openings being defined by a patterned photoresist.

16. The method of claim 15, wherein the process gas comprises a fluorocarbon and/or hydrofluorocarbon gas and the heating of the showerhead electrode reduces striations on the photoresist by controlling fluorine radical density in the process gas.

17. The method of claim 16, wherein the etching forms high aspect ratio contact openings in a silicon oxide layer.

18. The method of claim 10, further comprising cooling the showerhead electrode by conducting heat along a thermal path extending from the showerhead electrode to a gas distribution member, the thermal path member, the heater, one or more thermal chokes and a top wall.

19. The method of claim 18, wherein the applying power to the showerhead electrode comprises supplying RF power from a RF source outside the plasma etching chamber to a RF input located on the gas distribution member, through the gas distribution member and through multiple contact points between the gas distribution member and the showerhead electrode.

20. The method of claim 18, wherein the supplying gas comprises supplying gas from the gas distribution member to one or more plenums at the backside of the showerhead electrode.

21. The method of claim 10, wherein the supplying gas comprises supplying a first gas mixture to a central zone in the gap between the substrate and the showerhead electrode and supplying a second gas mixture to an annular zone in the gap surrounding the central zone, the second gas mixture being different from the first gas mixture or the second gas mixture being the same as the first gas mixture but supplied at a different flow rate than the first gas mixture.

22. The method of claim 10, comprising etching a batch of wafers one-by-one in the plasma etching chamber, the showerhead electrode being maintained at a substantially uniform temperature during processing of the batch of wafers.

23. The method of claim 10, wherein the heating of the showerhead electrode comprises heating a central portion and an edge portion of the showerhead electrode such that a temperature differential is less than 50°

C. between the center portion and the edge portion of the showerhead electrode.

24. The method of claim 10, wherein the heating of the showerhead electrode comprises heating a central portion and an edge portion of the showerhead electrode such that a temperature differential is less than 25°

C. between the center portion and the edge portion of the showerhead electrode.