Plasma reactor with heated source of a polymer-hardening precursor material

• US 6,218,312 B1
• Filed: 10/08/1998
• Issued: 04/17/2001
• Est. Priority Date: 05/13/1996
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Collins, Kenneth S., Keswick, Peter, Rice, Michael, Yang, Chan-Lon, Marks, Jeffrey, Buchberger, Douglas, Yin, Gerald Zheyao, Roderick, Craig A., Groechel, David W., Wong, Yuen-Kui, Mohn, Jon
• Primary Examiner(s): Bueker, Richard
• Assistant Examiner(s): FIELER, ERIN L
• Application Number:
  US08/987,509
• Time in Patent Office: 922 Days
• Field of Search: 118/723.R, 118/723.VE, 118/723.E, 118/712, 118/714, 156/345, 438/723, 438/724, 438/719
• US Class Current: 438/723
• CPC Class Codes: C23C 16/517 using a combination of discharges covered by two or more of groups C23C16/503 - C23C16/515
• CPC Class Codes: H01F 2029/143 with control winding for generating magnetic bias
• CPC Class Codes: H01J 2237/3343 Problems associated with etching
• CPC Class Codes: H01J 2237/3345 anisotropy
• CPC Class Codes: H01J 2237/3346 Selectivity
• CPC Class Codes: H01J 2237/3382 Polymerising
• 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 37/321 the radio frequency energy being inductively coupled to the plasma
• CPC Class Codes: H01J 37/32146 Amplitude modulation, includes pulsing
• CPC Class Codes: H01J 37/32165 Plural frequencies
• CPC Class Codes: H01J 37/32458 Vessel
• CPC Class Codes: H01J 37/32467 Material
• CPC Class Codes: H01J 37/32522 Temperature
• CPC Class Codes: H01J 37/32688 Multi-cusp fields
• CPC Class Codes: H01J 37/32706 Polarising the substrate
• CPC Class Codes: H01J 37/32871 Means for trapping or directing unwanted particles
• CPC Class Codes: H01L 21/31116 by dry-etching
• CPC Class Codes: H01L 21/6831 using electrostatic chucks

Abstract

A general method of the invention is to provide a polymer-hardening precursor piece (such as silicon, carbon, silicon carbide or silicon nitride, but preferably silicon) within the reactor chamber during an etch process with a fluoro-carbon or fluoro-hydrocarbon gas, and to heat the polymer-hardening precursor piece above the polymerization temperature sufficiently to achieve a desired increase in oxide-to-silicon etch selectivity. Generally, this polymer-hardening precursor or silicon piece may be an integral part of the reactor chamber walls and/or ceiling or a separate, expendable and quickly removable piece, and the heating/cooling apparatus may be of any suitable type including apparatus which conductively or remotely heats the silicon piece.

Claims

1. A plasma reactor comprising:

a reactor chamber;

a plasma source power coupling apparatus near said chamber and an RF power source for supplying RF power to said plasma source power coupling apparatus;

a process gas inlet and a process gas supply coupled to said inlet for furnishing a process gas containing etchant and polymer precursors;

a support for holding an article to be processed inside said reactor chamber;

a polymer-hardening precursor piece maintained at a temperature sufficiently above a polymer condensation temperature so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 1.5;

a bore hole in said polymer-hardening precursor piece;

a temperature sensor and an optical fiber coupling said temperature sensor to said bore hole, said one end of said optical fiber extending inwardly at least partially into said bore hole; and

wherein said bore hole has a sufficiently high aspect ratio to reduce apparent variation of said emissivity with temperature observed by said sensor.

2. A plasma reactor comprising:

a reactor chamber;

a plasma source power coupling apparatus near said chamber and an RF power source for supplying RF power to said plasma source power coupling apparatus;

a process gas inlet and a process gas supply coupled to said inlet for furnishing a process gas containing etchant and polymer precursors;

a support for holding an article to be processed inside said reactor chamber;

a polymer-hardening precursor piece maintained at a temperature sufficiently above a polymer condensation temperature so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 1.5;

said polymer-hardening precursor piece comprises an expendable removable piece separable from structural elements of said chamber;

a remote temperature sensor responsive at a sensor wavelength for measuring a temperature of said polymer-hardening precursor piece and a controller connected to receive a signal from said remote temperature sensor and connected to a control input of said heater to govern said heater in response to said remote temperature sensor;

an optical conduit between said sensor and a selected portion of said polymer-hardening precursor piece, said conduit being transmissive at said sensor wavelength; and

a radiating material planted on said selected portion of said polymer-hardening precursor piece and wherein said sensor wavelength coincides with an emission wavelength of said radiating material.

3. A method of operating a plasma reactor, said plasma reactor having a reactor chamber, a plasma source power applicator near said chamber and an RF power source for supplying RF power to said plasma source power applicator, a process gas inlet and a process gas supply coupled to said inlet for furnishing a process gas containing etchant and polymer precursors, and a support for holding an article to be processed inside said reactor chamber, the method comprising:

providing a polymer-hardening precursor piece inside said chamber; and

beginning at a first temperature of said polymer-hardening precursor piece above a polymer condensation temperature, increasing the temperature of said polymer-hardening precursor piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 1.5, relative to the selectivity at said first temperature.

4. The method of claim 3 wherein increasing the temperature comprises:

heating said polymer-hardening precursor piece sufficiently to permit said polymer-hardening precursor piece to react with a plasma in said reactor chamber.

5. The method of claim 3 wherein said step of supplying a polymer-hardening precursor piece comprises providing an expendable removable polymer-hardening precursor piece separable from structural elements of said chamber.

6. The method of claim 3 further comprising coupling an RF power source to said polymer-hardening precursor piece.

7. The method of claim 3 wherein providing a polymer-hardening precursor piece comprises:

providing a polymer-hardening precursor piece which contributes material from itself into a polymer formed on said article during the operating of said reactor, said material contributed to said polymer by said polymer-hardening precursor piece increasing resistance of said polymer to etching by an etchant derived from an etchant precursor of said process gas.

8. The method of claim 3 wherein providing said polymer-hardening precursor piece comprises:

providing a polymer-hardening precursor piece which is a scavenger for an etchant derived from an etch precursor of said process gas.

9. The method of claim 3 wherein providing said process gas further comprises:

providing a process gas which is comprised of at least flourine and carbon.

10. The method of claim 3 wherein providing said polymer-hardening precursor piece further comprises:

providing as said polymer-hardening precursor piece at least one of;

(a) silicon, (b) carbon, (c) silicon carbide, (d) silicon nitride.

11. The method of claim 10 wherein:

providing said article to be processed comprises providing a planar wafer; and

providing said polymer-hardening precursor piece comprises providing said polymer-hardening precursor piece shaped as an annular planar ring concentric with or near a circumference of said wafer.

12. The method of claim 11 wherein providing said polymer-hardening precursor piece shaped as an annular ring further comprises positioning said polymer-hardening precursor piece substantially co-planar with said wafer.

13. The method of claim 4 further comprising measuring a temperature of said polymer-hardening precursor piece with a remote temperature sensor responsive at a sensor wavelength and governing said heating in response to said temperature of said piece.

14. The method of claim 13 wherein emissivity of said polymer-hardening precursor piece varies with temperature, and wherein said measuring comprises:

providing a bore hole in said polymer-hardening precursor piece;

providing said remote temperature sensor and an optical fiber coupling said temperature sensor to said bore hole, said one end of said optical fiber extending inwardly at least partially into said bore hole; and

wherein said bore hole has a sufficiently high aspect ratio to reduce apparent variation of said emissivity with temperature observed by said sensor.

15. The method of claim 13 wherein said heating further comprises emitting heat at a heater wavelength within an absorption spectrum of said polymer-hardening precursor piece.

16. The method of claim 15 wherein said heater wavelength and said sensor wavelength are different.

17. The method of claim 15 wherein said heater wavelength and said sensor wavelength lie within at least partially coinciding wavelength ranges.

18. The method of claim 15 wherein said heating further comprises separating said heater and sensor from said polymer-hardening precursor piece with a window, said window being transissive at least at said heater wavelength.

19. The method of claim 13 wherein said measuring further comprises:

providing an optical conduit between said sensor and a selected portion of said polymer-hardening precursor piece, said conduit being transmissive at said sensor wavelength.

20. The method of claim 19 wherein said measuring further comprises placing a radiating material in contact with said selected portion of said polymer-hardening precursor piece, wherein said sensor wavelength coincides with an emission wavelength of said radiating material.

21. The method of claim 19 wherein providing said optical conduit comprises providing an optical fiber having one end facing said sensor and another end facing said selected portion of said polymer-hardening precursor piece.

22. The method of claim 19 wherein said sensor wavelength coincides with an emission wavelength of said removable expendable piece, and wherein said optical conduit comprises a long wavelength transmissive material.

23. The method of claim 19 wherein providing an optical conduit comprises providing an optical conduit of a material that does not radiate strongly at said sensor wavelength in response to being heated.

24. The method of claim 3 wherein increasing the temperature of the polymer-hardening precursor piece comprises increasing the temperature of said polymer-hardening precursor piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 2.

25. The method of claim 3 wherein increasing the temperature of the polymer-hardening precursor piece comprises increasing the temperature of said polymer-hardening precursor piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 10.

26. The method of claim 3 wherein increasing the temperature of the polymer-hardening precursor piece comprises increasing the temperature of said polymer-hardening precursor piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 20.

27. The method of claim 3 wherein increasing the temperature of the polymer-hardening precursor piece comprises increasing the temperature of said polymer-hardening precursor piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 100.

28. A method of operating a plasma reactor, said plasma reactor having a reactor chamber, a plasma source power applicator near said chamber and an RF power source for supplying RF power to said plasma source power applicator, a process gas inlet and a process gas supply coupled to said inlet for furnishing a process gas containing etchant and polymer precursors, and a support for holding an article to be processed inside said reactor chamber, the method comprising:

providing a semiconductor material piece inside said chamber; and

beginning at a first temperature of said semiconductor material piece above a polymer condensation temperature, increasing the temperature of said semiconductor material piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 1.5 relative to the selectivity at said first temperature.

29. The method of claim 28 increasing said temperature comprises:

heating said semiconductor material piece sufficiently to permit said semiconductor material piece to react with a plasma in said reactor chamber.

30. The method of claim 28 wherein said step of supplying a semiconductor material piece comprises supplying an expendable removable piece separable from structural elements of said chamber.

31. The method of claim 28 wherein providing said process gas further comprises:

providing a process gas which is comprised of at least flourine and carbon.

32. The method of claim 28 wherein providing said semiconductor material piece comprises:

providing as said semiconductor material piece at least one of;

(a) silicon, (b) carbon, (c) silicon carbide, (d) silicon nitride.

33. The method of claim 28 wherein increasing the temperature of the semiconductor material piece further comprises increasing the temperature of said semiconductor material piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 2.

34. The method of claim 28 wherein increasing the temperature of the semiconductor material piece comprises increasing the temperature of said semiconductor material piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 10.

35. The method of claim 28 wherein increasing the temperature of the semiconductor material piece comprises increasing the temperature of said semiconductor material piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 20.

36. The method of claim 28 wherein increasing the temperature of the semiconductor material piece comprises increasing the temperature of said semiconductor material piece so as to increase etch selectivity of oxygen-containing material on said article to non-oxygen-containing material on said article until the selectivity has increased by a factor of at least about 100.