System and method for dampening high pressure impact on porous materials

• US 20040211440A1
• Filed: 04/24/2003
• Published: 10/28/2004
• Est. Priority Date: 04/24/2003
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Lo, Henry, Wang, Ching-Ya, Lin, Yu-Liang, Zhou, Mei-Sheng, Chuang, Ping
• Granted Patent: US 6,875,285 B2
• Time in Patent Office: Days
• US Class Current: 134/2
• CPC Class Codes: B08B 7/0021 by liquid gases or supercritical fluids
• CPC Class Codes: H01L 21/02052 Wet cleaning only H01L21/02085 takes precedence
• CPC Class Codes: H01L 21/31116 by dry-etching

Abstract

System and method for reducing damage to a semiconductor substrate when using cleaning fluids at elevated pressures to clean the semiconductor substrates. A preferred embodiment comprises applying the cleaning fluid at a first pressure for a first time period, wherein the first pressure is relatively low, and then increasing the pressure of the cleaning fluid to a pressure level that can effectively clean the semiconductor substrate and maintaining the pressure level for a second time period. The application of the cleaning fluid at the relatively low initial pressure acts as a temporary filler and creates a buffer of the cleaning fluid on the semiconductor substrate and helps to dampen the impact of the subsequent high pressure application of the cleaning fluid on the semiconductor substrate.

Claims

1. A method for cleaning a semiconductor substrate comprising:

applying a cleaning fluid at a first pressure for a first time period; and

applying the cleaning fluid at a second pressure for a second time period, wherein the second pressure is greater than the first pressure.

2. The method of claim 1, wherein the semiconductor substrate is made of a material with a low dielectric coefficient.

3. The method of claim 1, wherein the cleaning fluid is a supercritical fluid.

4. The method of claim 1, wherein the cleaning fluid is carbon dioxide.

5. The method of claim 1, wherein the first pressure is on the order of several atmospheres.

6. The method of claim 5, wherein the second pressure is at least ten times the first pressure.

7. The method of claim 1, wherein the first pressure and the second pressure are determined by physical and chemical characteristics of the semiconductor substrate.

8. The method of claim 7, wherein the semiconductor substrate may have pores and imperfections, and wherein the first pressure and second pressure are determined by the size of the pores and imperfections.

9. The method of claim 1, wherein the first time and second time are determined by physical and chemical characteristics of the semiconductor substrate.

10. The method of claim 9, wherein the semiconductor substrate may have pores and imperfections, and wherein the first time and second time are determined by the size of the pores and imperfections.

11. The method of claim 1, wherein the first pressure and the second pressure are determined by chemical characteristics of the cleaning fluid.

12. The method of claim 1, wherein the first time and second time are determined by chemical characteristics of the cleaning fluid.

13. The method of claim 1, wherein the cleaning fluid is applied at increasing pressures from the first pressure to the second pressure.

14. The method of claim 1, wherein the cleaning fluid is applied at a third pressure for a third time period, between the first and second applying.

15. A semiconductor substrate cleaner comprising:

a cleaning fluid pump coupled to a cleaning fluid working tank, the cleaning fluid pump to apply a cleaning fluid at different pressure levels;

a process vessel coupled to the cleaning fluid pump, the process vessel to contain the semiconductor substrate while cleaning; and

an end-point detector coupled to the process vessel, the end-point detector to determine when to stop the application of the cleaning fluid.

16. The semiconductor substrate cleaner of claim 15, wherein the end-point detector programs the cleaning fluid pump to provide the cleaning fluid at different pressure levels.

17. The semiconductor substrate cleaner of claim 15, wherein the end-point detector determines when to stop by measuring elapsed time.

18. The semiconductor substrate cleaner of claim 15, wherein the end-point detector determines when to stop by measuring spent cleaning fluid.

19. The semiconductor substrate cleaner of claim 15 further comprising a co-solvent supply tank coupled to the process vessel, the co-solvent supply tank to provide a co-solvent to help improve cleaning performance.

20. The semiconductor substrate cleaner of claim 15 further comprising a heater with an input coupled to the cleaning fluid pump and an output coupled to the process vessel, the heater to elevate a temperature of the cleaning fluid.

21. The semiconductor substrate cleaner of claim 20, wherein the heater is programmable, and wherein the heater can be configured to change the temperature of the cleaning fluid.

22. A semiconductor substrate cleaner comprising:

a cleaning fluid pump coupled to a cleaning fluid working tank, the cleaning fluid pump configured to provide a cleaning fluid at a first pressure level for a first period of time and then at a second pressure level for a second period of time;

a process vessel coupled to the cleaning fluid pump, the process vessel to contain the semiconductor substrate while cleaning; and

an end-point detector coupled to the process vessel, the end-point detector to determine when to stop the application of the cleaning fluid.

23. The semiconductor substrate cleaner of claim 22, wherein the cleaning fluid pump provides the cleaning fluid at a third pressure level for a third period of time between the first and second periods of time.

24. The semiconductor substrate cleaner of claim 22, wherein the cleaning fluid pump provides the cleaning fluid at an increasing pressure level, starting at the first pressure and ending at the second pressure.