Patent US4936930A successfully refreshed from Google Patents.
US4936930A
Expired / Lapsed
US
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Method for improved alignment for semiconductor devices with buried layers
Assignee: Vishay Siliconix Inc
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Filing: 1988-01-06
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Granted: 1990-06-26
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Expires: 2008-01-06
Abstract
Abstract A method is provided to improve the alignment process in fabricating an integrated circuit with buried layers. The buried layers are implanted in a substrate and driven in, but without the usual step at their perimeter. A target pattern is etched into the substrate surface by means of plasma-assisted etching. An isotropic epitaxial layer is then grown at reduced pressure over the substrate surface so that the target is replicated on the epitaxial layer surface. The target as replicated is thus suitable for optical alignment, either manually or by automatic alignment equipment.
Inventors
- 👤 Gilbert A. Gruber
- 👤 Zolik Fichtenholz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:25
CPC Classifications
H; H10; H10W; H10W46/00; H10W15/00; H10W15/01; H10W46/501; Y; Y10; Y10S; Y10S148/00; Y10S148/102; Y10S438/00; Y10S438/975
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
89 words
A semiconductor device comprising: a semiconductor substrate of a first conductivity type, having a principal surface; at least one region of a second conductivity type formed in said substrate; at least one target etched in said principal surface, said target being located at a known position relative to the position of said region and having an outline different from that of said region; and an isotropic crystal layer overlying and in contact with said principal surface, wherein said target is replicated on the surface of said isotropic crystal layer.
Claim 2
Dependent Claim
89 words
A semiconductor device comprising: a semiconductor substrate of a first conductivity type, having a principal surface; at least one region of a second conductivity type formed in said substrate; at least one target etched in said principal surface, said target being located at a known position relative to the position of said region and having an outline different from that of said region; and an isotropic crystal layer overlying and in contact with said principal surface, wherein said target is replicated on the surface of said isotropic crystal layer.
Claim 3
Dependent Claim
25 words
The device of claim 1, further comprising said target replicated on said surface of said isotropic crystal layer being readily detectable by optical alignment equipment.
Claim 4
Dependent Claim
15 words
The device of claim 1, wherein said isotropic crystal layer is formed by epitaxial growth.
Claim 5
Dependent Claim
18 words
The device of claim 1, wherein said isotropic crystal layer is formed by low ambient pressure epitaxial growth.
Claim 6
Dependent Claim
13 words
The device of claim 1, wherein said target is etched by plasma-assisted etching.
Claim 7
Dependent Claim
14 words
The device of claim 1, wherein said target is etched by reactive ion etching.
Claim 8
Dependent Claim
21 words
The device of claim 1, wherein said target comprises an etched-away area with an X-shaped area standing inside said etched-away area.
References Cited (Backward Citations)
US4125418A
Cited
US4256829A
Cited
JPS55160443A
Cited
US4503334A
Cited
JPS58102523A
Cited
JPS58106545A
Cited
JPS5939041A
Cited
JPS5948711A
Cited
US4639798A
Cited
US4572765A
Cited
JPS61123083A
Cited
JPS61174764A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-06-25 | 1993-12-25 | 1994-06-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-06-25 | 1997-12-25 | 1998-06-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-06-25 | 2001-12-25 | 2002-06-26 | $7700.00 | Window Closed / Lapsed |