US5324688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating a semiconductor acceleration sensor
Assignee: NEC Corp
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Filing: 1991-12-16
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Granted: 1994-06-28
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Expires: 2011-12-16
Abstract
Abstract A P-type impurity is diffused into an N-type epitaxial layer formed on a P-type silicon substrate. A gauge resistor for measuring deformation is formed on this epitaxial layer, with an aluminum wiring provided between the gauge resistor and a pad. Then, bottom-surface etching is performed on the resultant structure to remove a groove portion, thus forming a cantilever, weight portion and rim portion. The groove portion between the weight portion and rim portion is formed to penetrate through the P-type diffusion layer and become narrower toward the top surface from the bottom surface, thus preventing dust or the like from entering the groove portion. The etching from the bottom can reduce the number of required etching steps, ensuring lower fabrication cost.
Inventors
- 👤 Yuji Kondo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 04:20
CPC Classifications
G; G01; G01P; G01P15/00; G01P15/02; G01P15/08; G01P15/0802; G01P15/12; G01P15/123; H; H10; H10P; H10P50/00; H10P50/60; H10P50/61; H10P50/613; G01P2015/0805; G01P2015/0822; G01P2015/0825; G01P2015/0828
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
149 words
A method of fabricating a semiconductor acceleration sensor comprising the steps of: forming an epitaxial layer on a silicon substrate of one conductivity type, the epitaxial layer having the opposite conductivity type; diffusing impurities of the one conductivity type into a portion of the epitaxial layer deeper than the depth of the epitaxial layer to form a diffusion layer of the one conductivity type; forming a gauge resistor on the epitaxial layer and wiring the gauge resistor to a pad; and etching the silicon substrate from a bottom surface thereof to remove the silicon substrate to the depth of a top surface thereof at said portion where the diffusion layer is present and through a resulting exposed portion of the diffusion layer to thereby form a groove portion, the etching automatically stopping at the epitaxial layer at that portion where the gauge resistor is present to provide a cantilever.
Claim 2
Independent Claim
149 words
A method of fabricating a semiconductor acceleration sensor comprising the steps of: forming an epitaxial layer on a silicon substrate of one conductivity type, the epitaxial layer having the opposite conductivity type; diffusing impurities of the one conductivity type into a portion of the epitaxial layer deeper than the depth of the epitaxial layer to form a diffusion layer of the one conductivity type; forming a gauge resistor on the epitaxial layer and wiring the gauge resistor to a pad; and etching the silicon substrate from a bottom surface thereof to remove the silicon substrate to the depth of a top surface thereof at said portion where the diffusion layer is present and through a resulting exposed portion of the diffusion layer to thereby form a groove portion, the etching automatically stopping at the epitaxial layer at that portion where the gauge resistor is present to provide a cantilever.
Claim 3
Dependent Claim
24 words
A method according to claim 1, wherein the diffusion layer of the one conductivity type has a bottom surface larger than the groove portion.
Claim 4
Independent Claim
176 words
A method of fabricating a semiconductor acceleration sensor comprising the steps of: forming an epitaxial layer on a silicon substrate of one conductivity type, the epitaxial layer having the opposite conductivity type; diffusing impurities of the one conductivity type into a portion of the epitaxial layer deeper than the depth of the epitaxial layer to form a diffusion layer of the one conductivity type and making a bottom surface of the diffusion layer smaller than a groove region; forming a gauge resistor on the epitaxial layer and wiring the gauge resistor to a pad; and etching the silicon substrate from a bottom surface thereof to remove the silicon substrate to the depth of a top surface thereof at a center of that portion where the diffusion layer is present and through a resulting exposed portion of the diffusion layer and automatically stopping etching at the epitaxial layer at a peripheral portion, thereby forming a groove portion having a step, the etching automatically stopping at that portion where the gauge resistor is present to provide a cantilever.
Claim 5
Independent Claim
176 words
A method of fabricating a semiconductor acceleration sensor comprising the steps of: forming an epitaxial layer on a silicon substrate of one conductivity type, the epitaxial layer having the opposite conductivity type; diffusing impurities of the one conductivity type into a portion of the epitaxial layer deeper than the depth of the epitaxial layer to form a diffusion layer of the one conductivity type and making a bottom surface of the diffusion layer smaller than a groove region; forming a gauge resistor on the epitaxial layer and wiring the gauge resistor to a pad; and etching the silicon substrate from a bottom surface thereof to remove the silicon substrate to the depth of a top surface thereof at a center of that portion where the diffusion layer is present and through a resulting exposed portion of the diffusion layer and automatically stopping etching at the epitaxial layer at a peripheral portion, thereby forming a groove portion having a step, the etching automatically stopping at that portion where the gauge resistor is present to provide a cantilever.
References Cited (Backward Citations)
JPS6376483A
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JPH01224671A
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JPH01229976A
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JPH02156683A
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JPH02218172A
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JPH03200373A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1997-06-27 | 1997-12-27 | 1998-06-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-06-27 | 2001-12-27 | 2002-06-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-06-27 | 2005-12-27 | 2006-06-28 | $7700.00 | Window Closed / Lapsed |