Patent US3876472A successfully refreshed from Google Patents.
US3876472A
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Method of achieving semiconductor substrates having similar surface resistivity
Assignee: RCA Corp
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Filing: 1974-04-15
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Granted: 1975-04-08
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Expires: 1994-04-15
Abstract
Abstract A method of achieving semiconductor substrates having similar surface resistivity comprises implanting ions into semiconductor substrates of very high resistivity and then, preferably, subjecting the substrates to a drive-in diffusion. This method can be utilized in the manufacture of CMOS integrated circuits to achieve transistors having closely matched threshold voltages.
Inventors
- 👤 Murray Arthur Polinsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:20
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/01; H10D84/0123; H10D84/0126; H10D84/0165; H10D84/02; H10D84/03; H10D84/038; H10P; H10P32/00; H10P32/10; H10P32/14; H10P32/1404; H10P32/1406; H10P32/17; H10P32/171; H10P95/00
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
46 words
A METHOD OF ACHIEVING A PLURALITY OF SEMICONDUCTOR SUBSTRATES HAVING SIMILAR SURFACE RESISTIVITY COMPRISING: BOMBARDING SURFACES OF SEMICONDUCTOR SUBSTRATES OF ONE TYPE CONDUCTIVITY AND OF HIGH RESISTIVITY WITH IONS OF A CONDUCTIVITY MODIFIER OF SAID ONE TYPE CONDUCTIVITY WHEREBY SAID IONS ARE IMPLANTED BENEATH SAID SURFACES.
Claim 2
Independent Claim
46 words
A METHOD OF ACHIEVING A PLURALITY OF SEMICONDUCTOR SUBSTRATES HAVING SIMILAR SURFACE RESISTIVITY COMPRISING: BOMBARDING SURFACES OF SEMICONDUCTOR SUBSTRATES OF ONE TYPE CONDUCTIVITY AND OF HIGH RESISTIVITY WITH IONS OF A CONDUCTIVITY MODIFIER OF SAID ONE TYPE CONDUCTIVITY WHEREBY SAID IONS ARE IMPLANTED BENEATH SAID SURFACES.
Claim 3
Dependent Claim
13 words
A method as recited in claim 1 wherein said bombarding step is performed
Claim 4
Dependent Claim
47 words
A method as recited in claim 1 further comprising the step of heating said substrates to a temperature at which said implanted ions will diffuse into said substrates and maintaining said substrates at said temperature until a desired surface resistivity and diffused depth of said ions is
Claim 5
Dependent Claim
26 words
A method as recited in claim 3 further comprising the step of growing a layer of oxide of the material of said substrates onto said substrates
Claim 6
Dependent Claim
24 words
A method as recited in claim 1 wherein said substrates are silicon wafers of said one type conductivity having a resistivity between 25 and
Claim 7
Dependent Claim
14 words
A method as recited in claim 5 wherein said one type conductivity is N
Claim 8
Dependent Claim
13 words
A method as recited in claim 6 wherein said substrates are heated at
Claim 9
Independent Claim
65 words
A method of controlling the threshold voltage of a channel lying in a region of one type conductivity in a MOS transistor which includes a semiconductor substrate of one type conductivity having spaced source and drain regions of opposite type conductivity therein, said method comprising bombarding a surface of a semiconductor substrate of high resistivity with ions of a conductivity modifier of said one type
Claim 10
Independent Claim
65 words
A method of controlling the threshold voltage of a channel lying in a region of one type conductivity in a MOS transistor which includes a semiconductor substrate of one type conductivity having spaced source and drain regions of opposite type conductivity therein, said method comprising bombarding a surface of a semiconductor substrate of high resistivity with ions of a conductivity modifier of said one type
Claim 11
Dependent Claim
47 words
A method as recited in claim 8 further comprising the step of heating said substrate to a temperature at which said implanted ions will diffuse into said substrate and maintaining said substrate at said temperature until a desired surface conductivity and diffused depth of said ions is
Claim 12
Dependent Claim
34 words
A method as recited in claim 8 wherein said MOS transistor is disposed in a CMOS integrated circuit device and said controlling comprises matching the absolute values of the threshold voltages of the transistors
Claim 13
Dependent Claim
26 words
A method as recited in claim 10 wherein said substrate is a silicon wafer of said one type conductivity having a resistivity between 25 and 50
Claim 14
Independent Claim
140 words
A method of making a CMOS integrated circuit device comprising the steps of: bombarding a surface of a semiconductor substrate of one type conductivity and of high resistivity with ions of a conductivity modifier of said one type conductivity, forming a well region of an opposite type conductivity in said substrate adjacent to said surface, forming spaced source and drain regions of said one type conductivity in said well region adjacent to said surface, and spaced source and drain regions of said opposite type conductivity in said substrate adjacent to said surface, said source and drain regions defining the ends of channel regions adjacent to said surface, forming a layer of insulating material at least on portions of said surface overlying said channel regions, forming gate electrodes on portions of the surface of said layer overlying said channel regions, and
Claim 15
Independent Claim
140 words
A method of making a CMOS integrated circuit device comprising the steps of: bombarding a surface of a semiconductor substrate of one type conductivity and of high resistivity with ions of a conductivity modifier of said one type conductivity, forming a well region of an opposite type conductivity in said substrate adjacent to said surface, forming spaced source and drain regions of said one type conductivity in said well region adjacent to said surface, and spaced source and drain regions of said opposite type conductivity in said substrate adjacent to said surface, said source and drain regions defining the ends of channel regions adjacent to said surface, forming a layer of insulating material at least on portions of said surface overlying said channel regions, forming gate electrodes on portions of the surface of said layer overlying said channel regions, and
Claim 16
Dependent Claim
47 words
A method as recited in claim 12 further comprising the step of heating said substrate to a temperature at which said implanted ions will diffuse into said substrate and maintaining said substrate at said temperature until a desired surface conductivity and diffused depth of said ions is
Claim 17
Dependent Claim
26 words
A method as recited in claim 12 wherein said substrate is a silicon wafer of said one type conductivity having a resistivity between 25 and 50
Claim 18
Dependent Claim
15 words
A method as recited in claim 14 wherein said one type conductivity is N type.
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) | 1978-04-07 | 1978-10-07 | 1979-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-07 | 1982-10-07 | 1983-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-07 | 1986-10-07 | 1987-04-08 | $7700.00 | Window Closed / Lapsed |