Patent US4251300A successfully refreshed from Google Patents.
US4251300A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming shaped buried layers in semiconductor devices utilizing etching, epitaxial deposition and oxide formation
Assignee: National Semiconductor Corp
•
Filing: 1979-05-14
•
Granted: 1981-02-17
•
Expires: 1999-05-14
Abstract
Abstract A method for forming a shaped buried layer in a semiconductor structure includes the steps of removing a portion of semiconductor material from adjacent the surface of the semiconductor substrate to form an indentation, introducing a dopant into the surface of the indentation to form regions of impurity in the semiconductor substrate, forming a region of epitaxial material on the surface of the indentation, and forming regions of insulating material to surround the epitaxial material.
Inventors
- 👤 Robert E. Caldwell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:17
CPC Classifications
H; H10; H10W; H10W15/00; H10P; H10P14/00; H10P14/20; H10P14/24; H10P14/29; H10P14/2901; H10P14/2902; H10P14/2905; H10P14/2924; H10P14/2925; H10P14/2926; H10P14/34; H10P14/3402; H10P14/3404; H10P14/3411; H10P14/3438; H10P14/3441; H10P14/3442; H10P14/3444; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0121; H10W10/0124; H10W10/10; H10W10/13; H10W15/01; Y; Y10; Y10S; Y10S438/00; Y10S438/965
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
159 words
A method of making at least one shaped buried layer in a semiconductor structure comprising: removing a selected portion of semiconductor material from adjacent a first surface of a semiconductor substrate wherever a shaped buried layer is desired, the surface of each thereby created indentation being referred to as the second surface of that indentation; introducing a first conductivity type impurity through the second surface into the semiconductor substrate to thereby form a region a region of impurity in the semiconductor substrate adjacent the second surface; depositing epitaxial semiconductor material on all of the first surface and on the second surface of every indentation; removing epitaxial material from all of the first surface; and forming regions of insulating material on the first surface and on portions of the epitaxial material to electrically isolate each region of epitaxial material on the second surface of every indentation from every other region of epitaxial material on the second surface of every indentation.
Claim 2
Independent Claim
159 words
A method of making at least one shaped buried layer in a semiconductor structure comprising: removing a selected portion of semiconductor material from adjacent a first surface of a semiconductor substrate wherever a shaped buried layer is desired, the surface of each thereby created indentation being referred to as the second surface of that indentation; introducing a first conductivity type impurity through the second surface into the semiconductor substrate to thereby form a region a region of impurity in the semiconductor substrate adjacent the second surface; depositing epitaxial semiconductor material on all of the first surface and on the second surface of every indentation; removing epitaxial material from all of the first surface; and forming regions of insulating material on the first surface and on portions of the epitaxial material to electrically isolate each region of epitaxial material on the second surface of every indentation from every other region of epitaxial material on the second surface of every indentation.
Claim 3
Dependent Claim
13 words
A method as in claim 1 wherein the first surface is substantially planar.
Claim 4
Dependent Claim
24 words
A method as in claim 2 wherein: the semiconductor substrate is silicon; the epitaxial material is silicon; and the insulating material is silicon dioxide.
Claim 5
Dependent Claim
13 words
A method as in claim 3 wherein the substrate is off-orientation [100] silicon.
Claim 6
Dependent Claim
23 words
A method as in claim 3 wherein: the substrate is p conductivity type; and the first conductivity type impurity is n conductivity type.
Claim 7
Dependent Claim
57 words
A method as in claim 1 wherein the step in removing a selected portion includes: forming a masking layer over all portions of the first surface, except the portion of the first surface overlying the at least one selected portion of semiconductor material; and etching the portions of the first surface not overlaid by the masking layer.
Claim 8
Dependent Claim
15 words
A method as in claim 6 wherein the etching is accomplished using a chemical etchant.
Claim 9
Dependent Claim
32 words
A method as in claim 6 wherein the masking layer is formed over all of the first surface and then removed from the portion of the first surface overlying the selected portion.
Claim 10
Dependent Claim
33 words
A method as in claim 6 wherein: the first conductivity type impurity is introduced into the second surface by diffusion; and the masking layer prevents the impurity from diffusing into the first surface.
Claim 11
Dependent Claim
31 words
A method as in claim 1 including the subsequent step of introducing a second conductivity type impurity of opposite conductivity to the first conductivity type into each region of epitaxial material.
Claim 12
Dependent Claim
42 words
A method as in claim 1 wherein the step of removing epitaxial material is accomplished by: forming a mask over those portions of the epitaxial material overlying the second surface; and etching the epitaxial material which is not overlaid by the mask.
Claim 13
Dependent Claim
18 words
A method as in claim 11 wherein: the mask is silicon nitride; and the epitaxial material is silicon.
Claim 14
Dependent Claim
28 words
A method as in claim 1 wherein: the substrate is silicon; and the step of forming regions of insulating material is accomplished by thermal oxidation of the substrate.
References Cited (Backward Citations)
US3456169A
Cited
US3370995A
Cited
US3728166A
Cited
US3764409A
Cited
US3740276A
Cited
US3648125A
Cited
US4101350A
Cited
US4056413A
Cited
US4089021A
Cited
US4143455A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-02-17 | 1984-08-18 | 1985-02-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-02-17 | 1988-08-18 | 1989-02-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-02-17 | 1992-08-18 | 1993-02-17 | $7700.00 | Window Closed / Lapsed |