Method of cleaning a process tube

• US 5,254,176 A
• Filed: 02/03/1992
• Issued: 10/19/1993
• Est. Priority Date: 02/03/1992
• Status: Expired due to Term

• Current Assignee: Iwatani International Corporation, Tokyo Electron Limited
• Original Assignee: Iwatani International Corporation, Tokyo Electron Limited
• Inventors: Nogami, Chitoshi, Ibuka, Shigehito
• Primary Examiner(s): Morris, Theodore
• Assistant Examiner(s): EL ARINI, ZEINAB
• Application Number:
  US07/829,508
• Time in Patent Office: 624 Days
• Field of Search: 134/2, 134/3, 134/21, 134/22.11
• US Class Current: 134/2
• CPC Class Codes: C03C 23/0075 Cleaning of glass specially adapted to plate glass B08B11/00
• CPC Class Codes: C23C 16/4405 Cleaning of reactor or parts inside the reactor by using reactive gases
• CPC Class Codes: H01L 21/67028 for cleaning followed by drying, rinsing, stripping, blasting or the like

Abstract

A method of cleaning the process tube of the CVD apparatus comprising carrying silicon wafers out of the process tube, making temperature in the process tube lower enough than the process temperature, that is, equal to or higher than room temperature, and supplying cleaning gas, in which ClF₃ is contained, into the process tube to react with poly-silicon and amorphous silicon (Si) stuck to that portion of the inner wall of the process tube which is not in the uniformly-heated zone in the process tube, whereby the matters stuck can be removed from the inner wall of the process tube for a shorter time.

Claims

1. A cleaning method for removing a low density silicon-based film adhered to an inner wall of a ceramic process tube in a process of forming a silicon-based film on a semiconductor wafer, comprising the steps of:

taking a wafer having a silicon-based film formed thereon out of said process tube;

then

controlling the temperature within the process tube to fall within a range of between 400°

C. and the boiling point of ClF₃ ;

supplying, while the temperature is controlled to be below 400°

C., a cleaning gas containing ClF₃ into the process tube to allow said cleaning gas to react with said low density silicon-based film; and

releasing the gaseous material from the process tube.

2. A method according to claim 1, further comprising:

supplying said cleaning gas in the process tube and making internal pressure in the process tube negative while exhausting the process tube through an exhaust means; and

reacting said cleaning gas with mono-crystal-silicon, poly-crystal-silicon and/or amorphous silicon which have/has adhered, during the SiO₂ film forming process, to the inner wall of zones, other than uniformly heated zone.

3. The method according to claim 2, wherein a dry pump of the oil-free type is used as the exhaust means.

4. The method according to claim 1, wherein a heating power supply is switched off to lower the temperature in the process tube substantially to room temperature and the cleaning gas is then supplied into the process tube.

5. The method according to claim 1, wherein the cleaning gas includes at least one of oxygen gas, nitrogen gas, argon gas and CF₄ gas.

6. The method according to claim 1, wherein the process tube is made of quartz.

7. A method according to claim 1, wherein the process tube walls comprise silicon dioxide.

8. A method according to claim 1, further comprising the step of:

ultrasonically vibrating the process tube while ClF₃ is inside the process tube.

9. A method according to claim 8, wherein ultrasonically vibrating further comprises applying strong and weak ultrasonic waves.

11. The method according to claim 1 or 10, wherein the inner pressure of the process tube is controlled to fall within a range of between 0.1 to 2 Torr in the step of supplying said cleaning gas into said process tube.

12. The method according to claim 1 or 10, further comprising the step of calculating a cumulative operating time of said process tube before the step of controlling the temperature within the process tube, said cleaning gas being supplied to the process tube when the cumulative operating time has been found to exceed a certain value.

14. The method according to claim 1 or 10, further comprising the step of transferring a wafer support member supporting wafers within said process tube into the process tube before the step of taking the wafer having a film-forming treatment applied thereto out of the process tube.

10. A method of heat-treating a semiconductor wafer within a process tube, comprising the steps of:

forming a silicon-based film on a semiconductor wafer and taking said wafer having a silicon-based film formed thereon out of said process tube;

then

controlling the temperature within the process tube to fall within a range of between 400°

C. and the boiling point of ClF₃ ;

supplying, while the temperature is controlled to be below 400°

C., a cleaning gas containing ClF₃ into the process tube to allow said cleaning gas to react with a low density silicon-based film adhered to said process tube during formation of the silicon-based film on said wafer; and

releasing the gaseous material from the process tube.

13. The method according to claim 10, wherein a film-forming treatment is applied within said process tube to a plurality of wafers supported by a boat means.