Patent DE299064C successfully refreshed from Google Patents.
US4007104A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mesa fabrication process
Assignee: US Philips Corp
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Filing: 1975-10-22
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Granted: 1977-02-08
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Expires: 1995-10-22
Abstract
Abstract A method of manufacturing a semiconductor device wherein a semiconductor layer of one conductivity type is provided on a semiconductor body of the same conductivity type but of higher conductivity, a mesa is formed by etching away with a reactive gas plasma the semiconductor material around a masked area defining a mesa, and the mesa is then undercut by further etching by a gas plasma that removes material of the body faster than material of the layer so as to produce a bevelled mesa.
Inventors
- 👤 John Gilbert Summers
- 👤 Michael John Josh
- 👤 Mildred Avis Ayling
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:59
CPC Classifications
H; H10; H10P; H10P95/00; H10D; H10D99/00; H10P50/00; H10P50/60; H10P50/61; H10P50/613; Y; Y10; Y10S; Y10S438/00; Y10S438/978
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
202 words
A method of manufacturing a semiconductor device comprising: a. providing a semiconductor layer of one conductivity type on a semiconductor body portion of the same conductivity type but higher conductivity, b. forming an etch-masking layer on part of the semiconductor layer surface, and c. subjecting the semiconductor layer surface to an etching treatment in a gas plasma to etch through the semiconductor layer where exposed around said etch-masking layer and so leave a mesa portion of the semiconductor layer under said etch-masking layer and expose the part of said semiconductor body portion around said mesa portion, and, while using the etch-masking layer to mask the top of said mesa-portion, subjecting the exposed parts of said semiconductor body portion and said mesa portion to further etching which includes removing the material of said semiconductor body portion faster than that of said semiconductor layer to etch under said mesa portion of the semiconductor layer and cause the whole upper edge of said mesa portion to overhang the adjacent etched surface, the side of said mesa portion being bevelled by the further etching so that the area of the resulting mesa portion of the semiconductor layer increases from its interface with said semiconductor body portion.
Claim 2
Independent Claim
202 words
A method of manufacturing a semiconductor device comprising: a. providing a semiconductor layer of one conductivity type on a semiconductor body portion of the same conductivity type but higher conductivity, b. forming an etch-masking layer on part of the semiconductor layer surface, and c. subjecting the semiconductor layer surface to an etching treatment in a gas plasma to etch through the semiconductor layer where exposed around said etch-masking layer and so leave a mesa portion of the semiconductor layer under said etch-masking layer and expose the part of said semiconductor body portion around said mesa portion, and, while using the etch-masking layer to mask the top of said mesa-portion, subjecting the exposed parts of said semiconductor body portion and said mesa portion to further etching which includes removing the material of said semiconductor body portion faster than that of said semiconductor layer to etch under said mesa portion of the semiconductor layer and cause the whole upper edge of said mesa portion to overhang the adjacent etched surface, the side of said mesa portion being bevelled by the further etching so that the area of the resulting mesa portion of the semiconductor layer increases from its interface with said semiconductor body portion.
Claim 3
Dependent Claim
49 words
A method according to claim 1, in which said further etching to etch under said mesa portion and bevel its side is effected in a gas plasma formed by introducing a further gas into the gas plasma used for etching the semiconductor layer to expose the semiconductor body portion.
Claim 4
Dependent Claim
39 words
A method according to claim 2, in which the semiconductor layer and body portion are of silicon, and the plasma gas is CF 4 and contains between 2% and 4% of oxygen for underetching and bevelling said mesa portion.
Claim 5
Dependent Claim
32 words
A method according to claim 2, in which the etching which bevels the side of said mesa portion is terminated before said bevel extends to the upper edge of said mesa portion.
Claim 6
Dependent Claim
42 words
A method according to claim 1, in which both the etching of the semiconductor layer to expose the semiconductor body portion and said further etching to etch under said mesa portion and bevel its side are effected in the same gas plasma.
Claim 7
Dependent Claim
32 words
A method according to claim 5, in which the etching which bevels the side of said mesa portion is terminated before said bevel extends to the upper edge of said mesa portion.
Claim 8
Dependent Claim
39 words
A method according to claim 1, in which the etch-masking layer comprises a metal and is at least partly retained in the manufactured device to form at least part of an electrode on the mesa-portion of the semiconductor device.
References Cited (Backward Citations)
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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) | 1980-02-08 | 1980-08-09 | 1981-02-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-08 | 1984-08-09 | 1985-02-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-08 | 1988-08-09 | 1989-02-08 | $7700.00 | Window Closed / Lapsed |