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US5376233A
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Method for selectively etching oxides
Assignee: Texas Instruments Inc
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Filing: 1992-12-30
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Granted: 1994-12-27
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Expires: 2012-12-30
Abstract
Abstract A method for selectively etching oxides from the face of a semiconductor layer 10 is disclosed herein. The semiconductor layer 10 has at least first and second oxide regions 12 and 14 formed on the surface thereof. The oxides 12 and 14 may be doped oxides such as BPSG or PSG and/or thermally treated oxides such as a thermally grown oxide or a deposited oxide which is subsequently annealed. Native and chemical oxides are also considered. The semiconductor wafer 10 is heated to a temperature greater than room temperature (e.g., about 25 DEG C.) and a vapor phase hydrogen fluoride etch is performed so that one of the oxides 14 etches away at a rate significantly higher than the other oxide region 12. Other systems and methods are also disclosed.
Inventors
- 👤 Yong Man
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 09:49
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/10; H10P70/12; H10P70/125; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
93 words
A method of selectively etching oxides from the face of a semiconductor wafer comprising the steps of: providing a semiconductor wafer, said wafer having a first doped oxide region, and a second doped oxide region wherein said first doped oxide region has a dopant concentration greater than said second doped oxide region formed on the surface thereof; heating the wafer to a temperature greater than room temperature; and performing a vapor phase hydrogen fluoride etch such that said heavily doped oxide etches away at a rate higher than said lightly doped oxide region.
Claim 2
Independent Claim
93 words
A method of selectively etching oxides from the face of a semiconductor wafer comprising the steps of: providing a semiconductor wafer, said wafer having a first doped oxide region, and a second doped oxide region wherein said first doped oxide region has a dopant concentration greater than said second doped oxide region formed on the surface thereof; heating the wafer to a temperature greater than room temperature; and performing a vapor phase hydrogen fluoride etch such that said heavily doped oxide etches away at a rate higher than said lightly doped oxide region.
Claim 3
Dependent Claim
17 words
The method of claim 1 wherein said wafer is heated to between 35° C. and 50° C.
Claim 4
Dependent Claim
15 words
The method of claim 1 wherein said wafer is heated to less than 250° C.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein said first doped oxide region comprises a phosphosilicate glass region.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein said first doped oxide region comprises a borophosphosilicate glass region.
Claim 7
Dependent Claim
20 words
The method of claim 1 and further comprising the step of reducing the pressure to between 10 and 700 torr.
Claim 8
Dependent Claim
14 words
The method of claim 1, wherein said second doped oxide region comprises TEOS oxide.
Claim 9
Dependent Claim
18 words
The method of claim 1, wherein said second doped oxide region is a deposited oxide doped with boron.
Claim 10
Dependent Claim
20 words
The method of claim 1, wherein said second doped oxide region is a deposited oxide doped with arsenic and phosphorus.
Claim 11
Dependent Claim
19 words
The method of claim 1, wherein said heavily doped oxide region is located over said second doped oxide region.
Claim 12
Dependent Claim
35 words
The method of claim 1, wherein said heavily doped oxide region is located at the surface of the semiconductor wafer and said second doped oxide region is located at the surface of the semiconductor wafer.
Claim 13
Independent Claim
72 words
A method of selectively etching oxides from the face of a semiconductor wafer comprising the steps of: providing a semiconductor wafer, said wafer having a first oxide region and an annealed second oxide region formed on the surface thereof; heating the wafer to a temperature greater than room temperature; and performing a vapor phase hydrogen fluoride etch such that said first oxide region etches away faster than said annealed second oxide region.
Claim 14
Independent Claim
72 words
A method of selectively etching oxides from the face of a semiconductor wafer comprising the steps of: providing a semiconductor wafer, said wafer having a first oxide region and an annealed second oxide region formed on the surface thereof; heating the wafer to a temperature greater than room temperature; and performing a vapor phase hydrogen fluoride etch such that said first oxide region etches away faster than said annealed second oxide region.
Claim 15
Dependent Claim
14 words
The method of claim 12, wherein said first oxide region comprises a silicate glass.
Claim 16
Dependent Claim
25 words
The method of claim 12, wherein said first oxide region comprises a TEOS oxide and said annealed second oxide region comprises an annealed TEOS oxide.
Claim 17
Dependent Claim
15 words
The method of claim 12, wherein said annealed second oxide region is doped with boron.
Claim 18
Dependent Claim
17 words
The method of claim 12, wherein said annealed second oxide region is doped with arsenic and phosphorus.
Claim 19
Dependent Claim
17 words
The method of claim 12, wherein said wafer is heated to between 35° C. and 50° C.
Claim 20
Dependent Claim
15 words
The method of claim 12, wherein said wafer is heated to less than 250° C.
Claim 21
Dependent Claim
20 words
The method of claim 12 and further comprising the step of reducing the pressure to between 10 and 700 torr.
Claim 22
Dependent Claim
20 words
The method of claim 12 and further comprising the step of reducing the pressure to between 35 and 45 torr.
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) | 1997-12-26 | 1998-06-27 | 1998-12-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-12-26 | 2002-06-27 | 2002-12-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-12-26 | 2006-06-27 | 2006-12-27 | $7700.00 | Window Closed / Lapsed |