US3901737A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming a semiconductor structure having islands isolated by moats
Assignee: Signetics Corp
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Filing: 1974-02-15
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Granted: 1975-08-26
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Expires: 1994-02-15
Abstract
Abstract Isolated islands are formed in a semiconductor structure by moats which are formed either as an isotropically etched U-shaped moat or a anisotropically etched trapezoidal moat. The ion implantation to form P+ isolation regions occurs only through the bottom of the moat because of the thicker inclined side walls which act as an effective mask.
Inventors
- 👤 Somanath Dash
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 03:21
CPC Classifications
H; H10; H10P; H10P95/00; H10W; H10W10/00; H10W10/01; H10W10/041; H10W10/40; H10W74/00; H10W74/10; H10W74/131; Y; Y10; Y10S; Y10S148/00; Y10S148/051; Y10S148/085; Y10S148/106; Y10S148/115
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
169 words
A METHOD FOR FORMING A SEMICONDUCTOR STRUCTURE COMPRISING THE FOLLOWING STEPS: PROVIDING A SILICON SEMICONDUCTOR SUBSTRATE OF ONE CONDUCTIVITY TYPE AND HAVING A SURFACE: EPITAXIALLY DEPOSITING ON SAID SURFACE A LAYER OF SILICON SEMICONDUCTOR MATERIAL OF AN OPPOSITE CONDUCTIVITY TYPE AND HAVING A TOP SURFACE: FORMING AN ETCH RESISTANT MASK ON SAID TOP SURFACE WITH A PLURALITY OF WINDOWS, FORMIN BY THE USE OF AN ETCH AND THE MASK A PLURALITY OF MOATS EXTENDING DOWNWARDLY FROM SAID TOP SURFACE TO SAID SUBSTRATE MOATS HAVING WALLS AT LEAST PORTIONS OF WHICH ARE INCLINED AND A SUBSTANTIALLY FLAT BOTTOM, OXIDING SAID MOATS TO FORM AN OXIDE WALL: AND CAUSING BY ION IMPLANTATION AN IMPURITY OF SAID ONE CONDUCTIVITY TYPE TO ENTER SAID SUBSTRATE THROUGH THE BOTTOM OF SAID MOATS THE ENERGY OF THE ION IMPLANT BEING ADJUSTED SO AS TO PENETRATE THE EFFECTIVE THICKER INCLINED SIDE TO FORM ISOLATION REGIONS LIMITED TO THE AREA UNDER SAID BOTTOM OF SAID MOAT AND HAVING AN IMPURITY CONCENTRATION GREATER THAN THAT OF THE SUBSTRATE.
Claim 2
Independent Claim
169 words
A METHOD FOR FORMING A SEMICONDUCTOR STRUCTURE COMPRISING THE FOLLOWING STEPS: PROVIDING A SILICON SEMICONDUCTOR SUBSTRATE OF ONE CONDUCTIVITY TYPE AND HAVING A SURFACE: EPITAXIALLY DEPOSITING ON SAID SURFACE A LAYER OF SILICON SEMICONDUCTOR MATERIAL OF AN OPPOSITE CONDUCTIVITY TYPE AND HAVING A TOP SURFACE: FORMING AN ETCH RESISTANT MASK ON SAID TOP SURFACE WITH A PLURALITY OF WINDOWS, FORMIN BY THE USE OF AN ETCH AND THE MASK A PLURALITY OF MOATS EXTENDING DOWNWARDLY FROM SAID TOP SURFACE TO SAID SUBSTRATE MOATS HAVING WALLS AT LEAST PORTIONS OF WHICH ARE INCLINED AND A SUBSTANTIALLY FLAT BOTTOM, OXIDING SAID MOATS TO FORM AN OXIDE WALL: AND CAUSING BY ION IMPLANTATION AN IMPURITY OF SAID ONE CONDUCTIVITY TYPE TO ENTER SAID SUBSTRATE THROUGH THE BOTTOM OF SAID MOATS THE ENERGY OF THE ION IMPLANT BEING ADJUSTED SO AS TO PENETRATE THE EFFECTIVE THICKER INCLINED SIDE TO FORM ISOLATION REGIONS LIMITED TO THE AREA UNDER SAID BOTTOM OF SAID MOAT AND HAVING AN IMPURITY CONCENTRATION GREATER THAN THAT OF THE SUBSTRATE.
Claim 3
Dependent Claim
17 words
A method as in claim 1 where said etch is anisotropic and said moats are trapezoidally shaped.
Claim 4
Dependent Claim
16 words
A method as in claim 1 where said etch is isotropic and said moats are U-shaped.
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) | 1978-08-25 | 1979-02-24 | 1979-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-25 | 1983-02-24 | 1983-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-25 | 1987-02-24 | 1987-08-26 | $7700.00 | Window Closed / Lapsed |