Claims
- 1. A method of cleaning a process tube, comprising the steps of:
- loading a process tube set at a film-forming temperature with a plurality of semiconductor wafers;
- supplying a process gas into the process tube to form a silicon oxide-based film on each of said wafers;
- taking the wafers out of the process tube;
- controlling the temperature within the process tube to a temperature not higher than said film-forming temperature but higher than 450.degree. C.;
- supplying a cleaning gas containing ClF.sub.3 into the process tube to carry out reactions between the cleaning gas and a silicon oxide-based film adhered to the inner wall of the process tube so as to remove said silicon oxide-based film; and
- setting the temperature within the process tube at said film-forming temperature in preparation for the loading of the process tube with wafers which are to be processed.
- 2. The method according to claim 1, wherein said cleaning gas is prepared by diluting a ClF.sub.3 gas with a nitrogen gas such that the cleaning gas contains 20.+-.5% by volume of ClF.sub.3.
- 3. The method according to claim 1, wherein the axis of said process tube extends in a vertical direction.
- 4. The method according to claim 1, wherein said wafers are those which have had a silicon oxide-based film formed thereon at a process temperature of 600.degree. to 850.degree. C.
- 5. The method according to claim 1, wherein said cleaning gas is supplied into the process tube maintained at 450.degree. to 620.degree. C.
- 6. The method according to claim 1, wherein said silicon oxide film comprises a silicon dioxide film.
- 7. The method according to claim 1, wherein said silicon oxide-based film is a SiO.sub.2 film formed by using alkoxy silane, Si(OC.sub.2 H.sub.5).sub.4.
- 8. The method according to claim 1, wherein the wall itself of the process tube is heated for controlling the temperature within the process tube.
- 9. The method according to claim 1, further comprising the steps of:
- calculating the accumulated time of the film-forming process during which the wafer stays in the process tube for formation of a silicon oxide-based film thereon; and
- determining whether the accumulated process time exceeds a reference time and, when the reference time is exceeded, supplying a cleaning gas into the process tube.
- 10. The method according to claim 1, further comprising the steps of:
- calculating the accumulated number of film-forming operations during which the wafer is put in and taken out of the process tube for formation of a silicon oxide-based film thereon; and
- determining whether the accumulated number of film-forming operations exceeds a reference number and, when the reference number is exceeded, supplying said cleaning gas into the process tube.
- 11. The method according to claim 1, consisting essentially of the steps of:
- loading a process tube set at a film-forming temperature with a plurality of semiconductor wafers;
- supplying a process gas into the process tube to form a silicon oxide-based film on each of said wafers;
- taking the wafers out of the process tube;
- controlling the temperature within the process tube to a temperature not higher than said film-forming temperature but higher than 450.degree. C.;
- supplying a cleaning gas consisting of ClF.sub.3 and nitrogen into the process tube to carry out reactions between the cleaning gas and the silicon oxide-based film adhered to the inner wall of the process tube so as to remove said silicon oxide-based film; and
- setting the temperature within the process tube at said film-forming temperature in preparation for the loading of the process tube with wafers which are to be processed.
- 12. A method of cleaning a process tube, comprising the steps of:
- loading a process tube set at a film-forming temperature with a plurality of semiconductor wafers together with a boat and other support members;
- supplying a process gas into the process tube to form a silicon oxide-based film on each of said wafers;
- taking the wafers together with the boat and other support members out of the process tube;
- loading the process tube with the boat and other support members alone;
- controlling the temperature within the process tube to a temperature not higher than a film-forming temperature but higher than 450.degree. C.;
- supplying a cleaning gas containing ClF.sub.3 into the process tube to carry out reactions between the cleaning gas and a silicon oxide-based film adhered to the inner wall of the process tube, boat and other support members so a to remove said silicon oxide-based film;
- taking the boat and other support members out of the process tube; and
- setting the temperature within the process tube at a film-forming temperature in preparation for the loading of the process tube with wafers which are to be processed.
- 13. The method according to claim 12, wherein said cleaning gas is prepared by diluting a ClF.sub.3 gas with a nitrogen gas such that the cleaning gas contains 20.+-.5% by volume of ClF.sub.3.
- 14. The method according to claim 12, wherein the axis of said process tube extends in a vertical direction.
- 15. The method according to claim 12, wherein said wafers are those which have had a silicon oxide-based film formed thereon at a process temperature of 600.degree. to 850.degree. C.
- 16. The method according to claim 12, wherein said cleaning gas is supplied into the process tube maintained at 450.degree. to 620.degree. C.
- 17. The method according to claim 12, wherein said silicon oxide film comprises a silicon dioxide film.
- 18. A method of cleaning a process tube, comprising the steps of:
- preparing a process tube having an inner cylinder and an outer cylinder;
- taking a wafer having a film formed thereon out of the process tube;
- controlling the temperature within the process tube to a temperature not higher than a film-forming temperature but higher than 450.degree. C.; and
- introducing a cleaning gas containing ClF.sub.3 into a lower region of the inner cylinder of the process tube such that the cleaning gas flows upward along the inner wall of the inner cylinder and, then, flows downward through a clearance formed between the inner and outer cylinders so as to cause the cleaning gas to perform reactions with a silicon oxide-based film adhered to the inner and outer surfaces of the inner cylinder and the inner surface of the outer cylinder and, thus, to remove the silicon oxide-based film.
- 19. The method according to claim 18, further comprising the step of:
- introducing a process gas into a lower region of the inner cylinder of the process tube such that the process gas flows upward within the inner cylinder and, then, flows downward through a clearance formed between the inner and outer cylinders so as to form a silicon oxide-based film on the wafer.
Priority Claims (1)
Number |
Date |
Country |
Kind |
3-031852 |
Jan 1991 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 07/818,677, filed on Jan. 9, 1992, now abandoned.
US Referenced Citations (3)
Number |
Name |
Date |
Kind |
4310380 |
Flamm et al. |
Jan 1982 |
|
4568410 |
Thornquist |
Feb 1986 |
|
5022961 |
Izumi et al. |
Jun 1991 |
|
Continuations (1)
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Number |
Date |
Country |
Parent |
818677 |
Jan 1992 |
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