Patent US5425845A successfully refreshed from Google Patents.
US5425845A
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Method for selective removal of hard trench masks
Assignee: Texas Instruments Inc
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Filing: 1993-06-09
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Granted: 1995-06-20
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Expires: 2013-06-09
Abstract
Abstract After trench formation on a semiconductor wafer (14) using a hard trench mask containing a phosphosilicate glass top layer and an underlying thermal oxide layer, the phosphosilicate glass layer may be removed without substantially etching the thermal oxide layer. The wafer temperature is increased to at least 40° C. (36) prior to etching with an HF/H 2 O vapor (40-44).
Inventors
- 👤 Man Wong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 14:29
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283; H10W; H10W72/00; H10W72/071; H10W72/0711; H10W72/07141; H10W72/075; H10W72/07521; H10W72/851; H10W72/874; H10W72/884; H10W90/00; H10W90/701; H10W90/731; H10W90/736; H10W90/751; H10W90/756
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
69 words
A method for removing a hard trench mask having a glass top layer with an underlying oxide layer after trench formation on a wafer, comprising the steps of: raising the temperature of the wafer; generating an HF/H 2 O vapor; and exposing the wafer to said generated HF/H 2 O vapor for a duration greater than 10 seconds to remove said glass top layer leaving said underlying oxide layer.
Claim 2
Independent Claim
69 words
A method for removing a hard trench mask having a glass top layer with an underlying oxide layer after trench formation on a wafer, comprising the steps of: raising the temperature of the wafer; generating an HF/H 2 O vapor; and exposing the wafer to said generated HF/H 2 O vapor for a duration greater than 10 seconds to remove said glass top layer leaving said underlying oxide layer.
Claim 3
Dependent Claim
26 words
The method, as set forth in claim 1, wherein said wafer temperature raising step includes the step of raising the wafer temperature up to 50° C.
Claim 4
Dependent Claim
27 words
The method, as set forth in claim 1, wherein said wafer temperature raising step includes the step of raising the wafer temperature to at least 40° C.
Claim 5
Dependent Claim
26 words
The method, as set forth in claim 1, further comprising the steps of: enclosing the wafer within a reactor chamber; and decreasing the reactor chamber pressure.
Claim 6
Dependent Claim
33 words
The method, as set forth in claim 1, wherein said HF/H 2 O vapor generating step comprises the step of passing an inert carrier gas over an azeotropic solution of HF/H 2 O.
Claim 7
Dependent Claim
60 words
The method, as set forth in claim 1, wherein said HF/H 2 O vapor generating and exposing steps comprise the steps of: passing a nitrogen carrier gas at a first rate over a heated azeotropic solution of HF/H 2 O for generating an HF/H 2 O vapor; and passing said HF/H 2 O vapor over the wafer at a second.
Claim 8
Dependent Claim
24 words
The method, as set forth in claim 1, further comprising an over-etching step for achieving uniformity and total removal of said hard trench mask.
Claim 9
Dependent Claim
19 words
The method, as set forth in claim 1, wherein said glass ton layer is a phosphosilicate glass top layer.
Claim 10
Dependent Claim
19 words
The method, as set forth in claim 1, wherein said glass ton layer is a borophosphosilicate glass top layer.
Claim 11
Dependent Claim
19 words
The method, as set forth in claim 1, wherein said underlying oxide layer is an underlying thermal oxide layer.
Claim 12
Independent Claim
69 words
A method for etching a phosphosilicate glass formation from a structure containing an oxide formation, comprising the steps of: raising the temperature of the structure to greater than 40° C.; generating an etchant vapor; and exposing the structure to said generated etchant vapor for a duration greater than that required to remove said phosphosilicate glass formation in order to remove said phosphosilicate .glass formation but not said oxide formation.
Claim 13
Independent Claim
69 words
A method for etching a phosphosilicate glass formation from a structure containing an oxide formation, comprising the steps of: raising the temperature of the structure to greater than 40° C.; generating an etchant vapor; and exposing the structure to said generated etchant vapor for a duration greater than that required to remove said phosphosilicate glass formation in order to remove said phosphosilicate .glass formation but not said oxide formation.
Claim 14
Dependent Claim
25 words
The method, as set forth in claim 11, wherein said temperature raising step includes the step of raising the structure temperature up to 50° C.
Claim 15
Dependent Claim
26 words
The method, as set forth in claim 11, further comprising the steps of: enclosing the structure within a reactor chamber; and decreasing the reactor chamber pressure.
Claim 16
Dependent Claim
38 words
The method, as set forth in claim 11, wherein said etchant vapor generating step comprises the step of passing an inert carrier gas over an azeotropic solution of HF/H 2 O for generating an HF/H 2 O vapor.
Claim 17
Dependent Claim
59 words
The method, as set forth in claim 11, wherein said etchant vapor generating and exposing steps comprise the steps of: passing a nitrogen carrier gas at a first rate over a heated azeotropic solution of HF/H 2 O for generating an HF/H 2 O vapor; and passing said HF/H 2 O vapor over the structure at a second rate.
Claim 18
Dependent Claim
23 words
The method, as set forth in claim 11, further comprising an over-etching step for achieving uniformity and total removal of the phosphosilicate glass.
Claim 19
Dependent Claim
22 words
The method, as set forth in claim 11, wherein said phosphosilicate glass composes an outermost layer with an underlying thermal oxide layer.
Claim 20
Dependent Claim
31 words
The method of claim 1, wherein said step of exposing the wafer to said generated HF/H 2 O vapor lasts for a duration in the range of 30 to 50 seconds.
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) | 1998-06-19 | 1998-12-19 | 1999-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-06-19 | 2002-12-19 | 2003-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-06-19 | 2006-12-19 | 2007-06-20 | $7700.00 | Window Closed / Lapsed |