Method and apparatus for etching a deep trench

• US 20040097077A1
• Filed: 11/15/2002
• Published: 05/20/2004
• Est. Priority Date: 11/15/2002
• Status: Abandoned Application

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Hsu, Shu-Ting S., Kumar, Ajay, Nallan, Padmapani C.
• Application Number:
  US10/298,040
• Publication Number:
  US 20040097077A1
• Time in Patent Office: Days
• US Class Current: 438/689
• CPC Class Codes: B81B 2203/033 Trenches
• CPC Class Codes: B81C 1/00619 Forming high aspect ratio structures having deep steep walls
• CPC Class Codes: B81C 2201/0112 Bosch process
• CPC Class Codes: H01L 21/30655 comprising alternated and repeated etching and passivation steps, e.g. Bosch process

Abstract

A method for plasma etching a trench in a semiconductor substrate using a plurality of processing cycles comprising plasma etch and deposition periods, wherein a substrate bias power is pulsed during the etch periods.

Claims

1. A method for plasma etching a trench in a semiconductor substrate to reduce scalloping of the trench, comprising:

applying a plurality of processing cycles to the substrate, where each cycle comprises a plasma etch period and a plasma deposition period; and

pulsing a substrate bias power during the plasma etch period.

2. The method of claim 1 wherein the trench has a width between 1 to 20 μ

m and an aspect ratio of about 5 to 50.

3. The method of claim 1 wherein the trench has scallops having a peak-to-valley size that is less than 100 nm.

4. The method of claim 1 wherein the plasma etch period has a duration between 1 and 40 seconds.

5. The method of claim 1 wherein the plasma etch period comprises a plasma etch process that uses an etchant gas comprising SF₆.

6. The method of claim 1 wherein the plasma deposition period has a duration between 1 and 20 seconds.

7. The method of claim 1 wherein the plasma deposition period comprises a plasma process that uses at least one of a fluorocarbon gas and a hydrofluorocarbon gas.

8. The method of claim 7 wherein the fluorocarbon gas comprises C₄F₈.

9. The method of claim 7 wherein the hydrofluorocarbon gas comprises CHF₃.

10. The method of claim 1 wherein the pulsing step further comprises:

applying the substrate bias power between 1 and 30 milliseconds at a duty cycle of between 10 and 90%.

11. The method of claim 1 wherein the pulsing step further comprises:

applying the substrate bias power for about 6 milliseconds at a duty cycle of about 33%.

12. The method of claim 1 wherein a source power is continuously applied to the plasma while the substrate bias power is pulsed.

13. The method of claim 12 wherein the source power has a frequency of about 12.56 MHz and the substrate bias power has a frequency of about 400 KHz.

14. A computer-readable medium including software that, when executed by a processor, performs a method that causes an etch reactor to etch a trench in a semiconductor substrate to reduce scalloping of the trench, comprising:

applying a plurality of processing cycles to the substrate, where each cycle comprises a plasma etch period and a plasma deposition period; and

pulsing a substrate bias power during the plasma etch period.

15. The computer-readable medium of claim 14 wherein the trench has a width between 1 to 20 μ

m and an aspect ratio of about 5 to 50.

16. The computer readable medium of claim 14 wherein the trench has scallops having a peak-to-valley size that is less than 100 nm.

17. The computer-readable medium of claim 14 wherein the plasma etch period has a duration between 1 and 40 seconds.

18. The computer-readable medium of claim 14 wherein the plasma etch period comprises a plasma etch process that uses an etchant gas comprising SF₆.

19. The computer-readable medium of claim 14 wherein the plasma deposition period has a duration between 1 and 20 seconds.

20. The computer-readable medium of claim 14 wherein the plasma deposition period comprises a plasma process that uses at least one of a fluorocarbon gas and a hydrofluorocarbon gas.

21. The computer-readable medium of claim 20 wherein the fluorocarbon gas comprises C₄F₈.

22. The computer-readable medium of claim 20 wherein the hydrofluorocarbon gas comprises CHF₃.

23. The computer-readable medium of claim 14 wherein the pulsing step further comprises:

applying the substrate bias power between 1 and 30 milliseconds at a duty cycle of between 10 and 90%.

24. The computer-readable medium of claim 14 wherein the pulsing step further comprises:

applying the substrate bias power for about 6 milliseconds at a duty cycle of about 33%.

25. The method of claim 14 wherein a source power is continuously applied to the plasma while the substrate bias power is pulsed.

26. The method of claim 14 wherein the source power has a frequency of about 12.56 MHz and the substrate bias power has a frequency of about 400 KHz.