US5968279A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of cleaning wafer substrates
Assignee: Mattson Technology Inc
•
Filing: 1997-06-13
•
Granted: 1999-10-19
•
Expires: 2017-06-13
Abstract
Abstract The silicon surface of a wafer is cleaned at room temperature in a separate pre-clean chamber prior to epitaxial deposition. Fluorine atoms generated, for example, from NF3 gas, enter the pre-clean chamber, contact the silicon surface, and etch away native oxide, contaminated silicon, and other damage incurred from prior wafer processes. The cleaned wafer is then transferred in an oxygen-free environment to a deposition chamber, for epitaxial deposition. By cleaning at reduced temperatures, autodoping, slip, and other stress-related problems are alleviated. By using a separate chamber for cleaning, system throughput is increased when compared to prior systems using conventional cleaning methods.
Inventors
- 👤 Joseph H. MacLeish
- 👤 Mahesh K. Sanganeria
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:30
CPC Classifications
H; H10; H10P; H10P72/00; H10P72/04; H10P72/0402; H10P72/0406
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
54 words
A method for cleaning a silicon surface comprising: inserting a wafer into a pre-clean chamber, wherein said pre-clean chamber is separate from a deposition chamber; and introducing a nitrogen trifluoride gas mixture into said pre-clean chamber, wherein said wafer in said pre-clean chamber is at a temperature lower than a temperature for epitaxial deposition.
Claim 2
Independent Claim
54 words
A method for cleaning a silicon surface comprising: inserting a wafer into a pre-clean chamber, wherein said pre-clean chamber is separate from a deposition chamber; and introducing a nitrogen trifluoride gas mixture into said pre-clean chamber, wherein said wafer in said pre-clean chamber is at a temperature lower than a temperature for epitaxial deposition.
Claim 3
Dependent Claim
39 words
The method of claim 1 wherein said nitrogen trifluoride gas mixture comprises a diluent at a flow rate in the range of approximately 20-200 sccm and nitrogen trifluoride at a flow rate in the range of approximately 2-30 sccm.
Claim 4
Dependent Claim
19 words
The method of claim 2 wherein said diluent is selected from the group consisting of argon, nitrogen and helium.
Claim 5
Dependent Claim
24 words
The method of claim 1 wherein said nitrogen trifluoride gas mixture is at a pressure in the range of approximately 0.1 to 10 torr.
Claim 6
Dependent Claim
24 words
The method of claim 1 wherein said nitrogen trifluoride gas mixture is subjected to an RF power in the range of approximately 100-500 watts.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein said temperature of said wafer is at approximately room temperature.
Claim 8
Independent Claim
48 words
A system for cleaning a silicon surface comprising a pre-clean chamber, wherein said pre-clean chamber is separate from a deposition chamber, and wherein said pre-clean chamber comprises means for introducing fluorine atoms into said pre-clean chamber for cleaning a wafer at a temperature lower than for epitaxial deposition.
Claim 9
Independent Claim
48 words
A system for cleaning a silicon surface comprising a pre-clean chamber, wherein said pre-clean chamber is separate from a deposition chamber, and wherein said pre-clean chamber comprises means for introducing fluorine atoms into said pre-clean chamber for cleaning a wafer at a temperature lower than for epitaxial deposition.
Claim 10
Dependent Claim
29 words
The method of claim 1, further comprising generating a plasma with said nitrogen trifluoride gas mixture by a plasma generator outside of said pre-clean chamber prior to said introducing.
Claim 11
Dependent Claim
24 words
The method of claim 1, further comprising heating nitrogen trifluoride gas by a heating source outside of said pre-claim chamber prior to said introducing.
Claim 12
Dependent Claim
25 words
The system of claim 7, further comprising a means for generating said fluorine atoms, wherein said means for generating are located outside said pre-clean chamber.
Claim 13
Dependent Claim
14 words
The system of claim 10, wherein said means for generating is a plasma generator.
Claim 14
Dependent Claim
14 words
The system of claim 10, wherein said means for generating is a heating source.
Claim 15
Dependent Claim
12 words
The system of claim 7, wherein said temperature is approximately room temperature.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-10-18 | 2003-04-19 | 2003-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-10-18 | 2007-04-19 | 2007-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-10-18 | 2011-04-19 | 2011-10-19 | $7700.00 | Window Closed / Lapsed |