Methods for etching using building blocks

• US 20040018739A1
• Filed: 07/26/2002
• Published: 01/29/2004
• Est. Priority Date: 07/26/2002
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Cheng, Stephanie S., Lill, Thorsten B., Shen, Meihua, Gani, Nicolas, Deshmukh, Shashank C., Abooameri, Farid
• Application Number:
  US10/206,252
• Publication Number:
  US 20040018739A1
• Time in Patent Office: Days
• US Class Current: 438/709
• CPC Class Codes: H01L 21/32137 of silicon-containing layers

Abstract

One embodiment of the present invention is a method used to fabricate an integrated circuit device on a wafer or substrate at a stage where a gate oxide is disposed over the wafer or substrate, a polysilicon layer is disposed thereover, a patterned hardmask is disposed thereover, a patterned antireflective coating is disposed thereover, and a patterned photoresist is disposed thereover, the method including steps of: (a) before stripping the photoresist, etching the polysilicon utilizing a first etch chemistry for a first period of time; and (b) etching the polysilicon utilizing a second etch chemistry for a second period of time.

Claims

1. A method used to fabricate an integrated circuit device on a wafer or substrate at a stage where a gate oxide is disposed over the wafer or substrate, a polysilicon layer is disposed thereover, a patterned hardmask is disposed thereover, a patterned antireflective coating is disposed thereover, and a patterned photoresist is disposed thereover, the method comprising steps of:

before stripping the photoresist, etching the polysilicon utilizing a first etch chemistry for a first period of time; and

etching the polysilicon utilizing a second etch chemistry for a second period of time.

2. The method of claim 1 which further comprises steps of:

before etching utilizing a second chemistry, stripping the photoresist and the antireflective coating.

3. The method of claim 1 wherein the first etch chemistry is relatively insensitive to doping of the polysilicon, and the second etch chemistry is sensitive to doping of the polysilicon.

4. The method of claim 1 wherein the first period and the second period vary as a function of doping sensitivity in the polysilicon.

5. The method of claim 4 wherein the first time increases relative to the second time as the doping sensitivity increases.

6. The method of claim 1 wherein the first period and the second period vary as a function of thickness of the photoresist.

7. The method of claim 6 wherein the first time decreases relative to the second time as the thickness of the photoresist decreases.

8. The method of claim 1 wherein the first etch chemistry is a 3-gas, fluorine-based, etch chemistry, and the second etch chemistry is a 4-gas, fluorine-based, etch chemistry.

9. The method of claim 1 wherein the 3-gas, fluorine-based, etch chemistry is a CF₄/Cl₂/N₂ chemistry, and the 4-gas, fluorine-based, etch chemistry is an HBr/Cl₂/CF₄/He-O₂ chemistry.

10. The method of claim 1 wherein the first time and the second time are determined by matching microtrenches produced by the first step of etching the polysilicon with feet produced by the second step of etching the polysilicon.

11. A method used to fabricate an integrated circuit device on a wafer or substrate at a stage where a gate oxide is disposed over the wafer or substrate, a polysilicon layer is disposed thereover, a hardmask is disposed thereover, an antireflective coating is disposed thereover, and a patterned photoresist is disposed thereover, the method comprising steps of:

etching to open the hardmask;

etching the polysilicon utilizing a first fluorine-based etch chemistry for a first period of time;

stripping the photoresist and the antireflective coating;

etching the polysilicon utilizing a second fluorine-based etch chemistry for a second period of time; and

overetching the polysilicon.

12. The method of claim 11 which further comprises first trim etching the patterned photoresist utilizing an HBr/O₂ chemistry.

13. The method of claim 12 wherein the trim etching utilizes a flow rate in a range from about 10 to 200 sccm for HBr;

and a flow rate in a range from about 10 to about 100 sccm for O₂.

14. The method of claim 12 wherein the trim etching utilizes a ratio of flow rates for HBr/O₂ in a range from about 0.5:

1 to about 2;

1.

15. The method of claim 11 wherein the hardmask open etch utilizes a passivation etch chemistry.

16. The method of claim 15 wherein the passivation chemistry is a CH_xF_Y etch chemistry.

17. The method of claim 16 wherein the CH_xF_y etch chemistry utilizes a flow rate in a range from about 20 to about 200 sccm for CF₄, a flow rate in a range from about 0 to about 100 sccm for CHF₃;

and a flow rate in a range from about 0 to about 100 sccm for CH₂F₂.

18. The method of claim 16 wherein the CH_xF_Y etch chemistry utilizes a ratio of flow rates for CHF₃/CF₄ in a range from about 0 to about 1.5:

1; and

a ratio of flow rates for CH₂F₂/CF₄ in a range from about 0 to about 1.5;

1.

19. The method of claim 11 wherein the first fluorine-based etch chemistry is a 3-gas, fluorine-based etch chemistry.

20. The method of claim 19 wherein the step of 3-gas chemistry etching utilizes a flow rate in a range from about 20 to about 200 sccm for CF₄;

a flow rate in a range from about 0 to about 100 sccm for Cl₂; and

a flow rate in a range from about 0 to about 100 sccm for N₂.

21. The method of claim 19 wherein the step of 3-gas chemistry etching utilizes a ratio of flow rates for CF₄/Cl₂ in a range from about 0.5:

1 to about 5;

1.

22. The method of claim 11 wherein the second fluorine-based etch chemistry is a 4-gas fluorine-based etch chemistry.

23. The method of claim 22 wherein the step of 4-gas chemistry etching utilizes a flow rate in a range from about 10 to about 200 sccm for Cl₂;

a flow rate in a range from about 0 to about 200 sccm for HBr;

a flow rate in a range from about 0 to about 50 sccm for He-O₂; and

a flow rate in a range from about 0 to about 200 sccm for CF₄.

24. The method of claim 22 wherein the step of 4-gas chemistry etching utilizes a ratio of flow rates for CF₄/Cl₂ in a range from about 0 to about 1:

1; and

a ratio of flow rates for Cl₂/HBr is in a range from about 0 to about 1;

1.

25. The method of claim 11 wherein the step of stripping comprises etching utilizing an oxygen chemistry.

26. The method of claim 11 which further comprises a step of breakthrough etching before etching the polysilicon utilizing a second fluorine-based etch chemistry for a second period of time, which breakthrough etching comprises etching utilizing a CF₄ chemistry.

27. The method of claim 26 wherein the step of breakthrough etching utilizes a flow rate in a range from about 10 to about 200 sccm for CF₄.

28. The method of claim 11 which further comprises a step of soft-landing etching after etching the polysilicon utilizing a second fluorine-based etch chemistry for a second period of time, which soft-landing etching comprises etching utilizing an HBr/Cl₂/O₂ chemistry.

29. The method of claim 28 wherein the step of soft-landing etching utilizes a flow rate in a range from about 10 to about 200 sccm for HBr;

a flow rate in a range from about 10 to about 200 sccm for Cl₂; and

a flow rate in a range from about 10 to about 200 sccm for O₂.

30. The method of claim 28 wherein the step of soft-landing etching utilizes a ratio of flow rates for O₂HBr in a range from about 0.2 to about 1:

1; and

a ratio of flow rates for Cl₂/HBr in a range from about 0 to about 1;

1.

31. The method of claim 11 wherein the step of overetching comprises etching utilizing an HBr/O₂ chemistry.

32. The method of claim 31 wherein the step of overetching utilizes a flow rate in a range from about 10 to about 200 sccm for HBr;

and a flow rate in a range from about 10 to about 200 sccm for O₂.

33. The method of claim 32 wherein the step of overetching utilizes a ratio of flow rates for HBr/O₂ in a range from about 4:

1 to about 100;

1.

34. The method of claim 16 wherein the CH_xF_Y etch chemistry utilizes a flow rate in a range from about 10 to about 100 sccm for CH₂F₂;

and a flow rate in a range from about 10 to about 100 sccm for O₂.

35. The method of claim 16 wherein the CH_xF_Y etch chemistry utilizes a ratio of flow rates for O₂/CH₂F₂ in a range from about 0.2:

1 to about 2;

1