Multiple state pulsing for high aspect ratio etch

Patent metadata

Field	Value
Publication number	US-12278112-B2
Application number	US-202218011505-A
Country	US
Kind code	B2
Filing date	Jun 16, 2022
Priority date	Jun 29, 2021
Publication date	Apr 15, 2025
Grant date	Apr 15, 2025

Abstract

A method for performing an etch process on a substrate includes applying a bias signal and a source signal to an electrode of a plasma processing system. The bias signal and the source signal are pulsed RF signals that together define a repeated pulsed RF cycle, wherein each pulsed RF cycle sequentially includes a first state, a second state, a third state, and a fourth state. The power level of the bias signal in the first state is greater than in the third state, which is greater than in the second state, which is greater than in the fourth state. The power level of the source signal in the first state is greater than in the third state, which is greater than in the second state, which is greater than in the fourth state.

First claim

The invention claimed is:

1. A method for performing an etch process on a substrate in a plasma processing system, comprising:
applying a bias signal to an electrode of the plasma processing system; and
applying a source signal to the electrode;
wherein the bias signal and the source signal are pulsed RF signals that together define a repeated pulsed RF cycle, wherein each pulsed RF cycle sequentially includes a first state, a second state, a third state, and a fourth state;
wherein the first state is defined by the bias signal being pulsed at a first bias power level and the source signal being pulsed at a first source power level;
wherein the second state is defined by the bias signal being pulsed at a second bias power level and the source signal being pulsed at a second source power level;
wherein the third state is defined by the bias signal being pulsed at a third bias power level and the source signal being pulsed at a third source power level;
wherein the fourth state is defined by the bias signal being pulsed at a fourth bias power level and the source signal being pulsed at a fourth source power level;
wherein the first bias power level is greater than the third bias power level, and the third bias power level is greater than the second bias power level, and the second bias power level is greater than the fourth bias power level;
wherein the first source power level is greater than the third source power level, and the third source power level is greater than the second source power level, and the second source power level is greater than the fourth source RF power level.

2. The method of claim 1 , wherein the second bias power level is less than the second source power level.

3. The method of claim 1 , wherein the second bias power level is about 1 to 20 percent of the first bias power level;
wherein the second source power level is about 20 to 70 percent of the first source power level.

4. The method of claim 1 , wherein the third bias power level is about 30 to 70 percent of the first bias power level;
wherein the third source power level is about 30 to 80 percent of the first source power level.

5. The method of claim 1 , wherein the fourth bias power level is a substantially zero power level, and wherein the fourth source power level is a substantially zero power level.

6. The method of claim 1 , wherein a duty cycle of the first state is approximately 3 to 30 percent of a duration of the pulsed RF cycle.

7. The method of claim 1 , wherein a duty cycle of the second state is approximately 3 to 30 percent of a duration of the pulsed RF cycle.

8. The method of claim 1 , wherein a duty cycle of the third state is approximately 3 to 30 percent of a duration of the pulsed RF cycle.

9. The method of claim 1 , wherein a duty cycle of the fourth state is approximately 35 to 75 percent of a duration of the pulsed RF cycle.

10. The method of claim 1 , wherein the bias signal has a frequency less than about 10 MHz, and wherein the source signal has a frequency greater than about 20 MHz.

11. The method of claim 1 , wherein the first state and the third state are configured to effect etching of a feature on a surface of the substrate.

12. The method of claim 11 , wherein the second state and the fourth state are configured to effect passivation of the feature on the surface of the substrate.

13. A controller device configured to cause a plasma processing system to perform an etch process on a substrate in said plasma processing system, the method including the following operations:
applying a bias signal to an electrode of the plasma processing system; and
applying a source signal to the electrode;
wherein the bias signal and the source signal are pulsed RF signals that together define a repeated pulsed RF cycle, wherein each pulsed RF cycle sequentially includes a first state, a second state, a third state, and a fourth state;
wherein the first state is defined by the bias signal being pulsed at a first bias power level and the source signal being pulsed at a first source power level;
wherein the second state is defined by the bias signal being pulsed at a second bias power level and the source signal being pulsed at a second source power level;
wherein the third state is defined by the bias signal being pulsed at a third bias power level and the source signal being pulsed at a third source power level;
wherein the fourth state is defined by the bias signal being pulsed at a fourth bias power level and the source signal being pulsed at a fourth source power level;
wherein the first bias power level is greater than the third bias power level, and the third bias power level is greater than the second bias power level, and the second bias power level is greater than the fourth bias power level;
wherein the first source power level is greater than the third source power level, and the third source power level is greater than the second source power level, and the second source power level is greater than the fourth source RF power level.

14. The controller device of claim 13 , wherein the second bias power level is less than the second source power level.

15. The controller device of claim 13 , wherein the second bias power level is about 1 to 20 percent of the first bias power level;
wherein the second source power level is about 20 to 70 percent of the first source power level.

16. The controller device of claim 13 , wherein the third bias power level is about 30 to 70 percent of the first bias power level;
wherein the third source power level is about 30 to 80 percent of the first source power level.

17. The controller device of claim 13 , wherein the fourth bias power level is a substantially zero power level, and wherein the fourth source power level is a substantially zero power level.

18. The controller device of claim 13 , wherein a duty cycle of the first state is approximately 3 to 10 percent of a duration of the pulsed RF cycle.

19. The controller device of claim 13 , wherein a duty cycle of the second state is approximately 6 to 25 percent of a duration of the pulsed RF cycle.

20. The controller device of claim 13 , wherein a duty cycle of the third state is approximately 10 to 30 percent of a duration of the pulsed RF cycle.

21. The controller device of claim 13 , wherein a duty cycle of the fourth state is approximately 35 to 75 percent of a duration of the pulsed RF cycle.

22. The controller device of claim 13 , wherein the bias signal has a frequency less than about 10 MHz, and wherein the source signal has a frequency greater than about 20 MHz.

23. The controller device of claim 13 , wherein the first state and the third state are configured to effect etching of a feature on a surface of the substrate.

24. The controller device of claim 22 , wherein the second state and the fourth state are configured to effect passivation of the feature on the surface of the substrate.

25. A method for performing an etch process on a substrate in a plasma processing system, comprising:
applying a bias signal to a first electrode of the plasma processing system; and
applying a source signal to a second electrode of the plasma processing system;
wherein the bias signal and the source signal are pulsed RF signals that together define a repeated pulsed RF cycle, wherein each pulsed RF cycle sequentially includes a first state, a second state, a third state, and a fourth state;
wherein the f

Assignees

• Lam Res Corp

Inventors

• Joi Aniruddha
• Dole Nikhil
• Wong Merrett
• Hudson Eric
• Sheth Jay

Classifications

• H10P50/242 Primary

  of Group IV materials · CPC title

• H10P50/283

  by chemical means · CPC title

• H01J2237/3346

  Selectivity · CPC title

• H01J37/32174

  Circuits specially adapted for controlling the RF discharge · CPC title

• H01J37/32165

  Plural frequencies · CPC title