US3909320A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for forming MOS structure using double diffusion
Assignee: Signetics Corp
•
Filing: 1973-12-26
•
Granted: 1975-09-30
•
Expires: 1993-12-26
Abstract
Abstract Method for forming a semiconductor structure by providing a semiconductor body having an impurity of one conductivity type and forming a gate oxide layer of relatively precise thickness which is not thereafter removed on the surface of the semiconductor body. A protective layer is then formed on the gate oxide to protect it from being etched and also from contamination. An opening is provided which exposes the surface of the semiconductor body adjacent the gate oxide. First and second impurities of opposite conductivity types are caused to enter through the opening utilizing one edge of the gate oxide as a mask to provide first and second regions within the semiconductor body of opposite conductivity types to form a precisely controlled channel. Source, gate and drain metallization is provided to complete the device.
Inventors
- 👤 Thomas P Gauge
- 👤 Joseph Kocsis
- 👤 James R Buchanan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:03
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/17; H10D62/213; H10D62/221; H10D62/235; H10D62/299; H10D62/307; H10D62/124; H10D62/126; H10D99/00
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
134 words
IN A METHOD FOR FORMING AN MOS STRUCTURE, PROVIDING A SEMICONDUCTOR BODY OF SILICON HAVING AN IMPURITY OF ONE CONDUCTIVELY TYPE AND HAVING A GENERALLY PLANAR SURFACE, FORMING A GATE LAYER OF SILICON DIOXIDE OF RELATIVELY PREICSE THICKNESS ON SAID SURFACE, PROVIDING A PROTECTIVE STRUCTURE ON SAID GATE LAYER, FORMING AN OPENING IN SAID PROTECTIVE STRUCTURE ADJACENT SAID GATE LAYER AND EXPOSING SAID SURFACE, CAUSING FIRST AND SECOND IMPURITIES TO PASS THROUGH SAID OPENING UTILIZING THE EDGES OF SAID PROTECTIVE STRUCTURE AS A MASK TO PROVIDE FIRST AND SECOND REGIONS OF DIFFERENT CONDUCTIVELY TYPES IN SAID SEMICONDUCTOR BODY AND TO PROVIDE A CHANNEL OF PRECISE LENGTH UNDERLYING THE GATE LAYER, REMOVING THE PROTECTIVE STRUCTURE FROM THE GATE LAYER AFTER FORMATION OF THE FIRST AND SECOND REGIONS, AND FORMING GATE, SOURCE AND DRAIN CONTACT METALLIZATION.
Claim 2
Dependent Claim
134 words
IN A METHOD FOR FORMING AN MOS STRUCTURE, PROVIDING A SEMICONDUCTOR BODY OF SILICON HAVING AN IMPURITY OF ONE CONDUCTIVELY TYPE AND HAVING A GENERALLY PLANAR SURFACE, FORMING A GATE LAYER OF SILICON DIOXIDE OF RELATIVELY PREICSE THICKNESS ON SAID SURFACE, PROVIDING A PROTECTIVE STRUCTURE ON SAID GATE LAYER, FORMING AN OPENING IN SAID PROTECTIVE STRUCTURE ADJACENT SAID GATE LAYER AND EXPOSING SAID SURFACE, CAUSING FIRST AND SECOND IMPURITIES TO PASS THROUGH SAID OPENING UTILIZING THE EDGES OF SAID PROTECTIVE STRUCTURE AS A MASK TO PROVIDE FIRST AND SECOND REGIONS OF DIFFERENT CONDUCTIVELY TYPES IN SAID SEMICONDUCTOR BODY AND TO PROVIDE A CHANNEL OF PRECISE LENGTH UNDERLYING THE GATE LAYER, REMOVING THE PROTECTIVE STRUCTURE FROM THE GATE LAYER AFTER FORMATION OF THE FIRST AND SECOND REGIONS, AND FORMING GATE, SOURCE AND DRAIN CONTACT METALLIZATION.
Claim 3
Dependent Claim
18 words
A method as in claim 1 wherein said protective structure includes a metal formed over said gate layer.
Claim 4
Dependent Claim
35 words
A method as in claim 1 wherein said protective structure includes a layer of polycrystalline silicon formed over said gate layer and wherein said polycrystalline silicon is doped with an impurity of one conductivity type.
Claim 5
Dependent Claim
46 words
A method as in claim 3 wherein said semiconductor body carries a P-type impurity and wherein said first and second diffusions are carried out by diffusing P-type and N-type impurities respectively and wherein an N-type impurity is diffused into said polycrystalline layer overlying said gate layer.
Claim 6
Dependent Claim
27 words
A method as in claim 1 together with the step of depositing a P-type impurity in the semiconductor body in a region remote from said gate layer.
Claim 7
Dependent Claim
21 words
A method as in claim 1 wherein said gate layer is formed to a thickness ranging from 600 to 1,500 Angstroms.
Claim 8
Dependent Claim
19 words
A method as in claim 6 wherein said gate layer is formed to a thickness of approximately 1,000 Angstroms.
Claim 9
Dependent Claim
41 words
A method as in claim 1 wherein said protective structure includes a layer of silicon nitride which is formed so that it overlies said gate layer and a silicon dioxide layer which is formed so that overlies said silicon nitride layer.
Claim 10
Dependent Claim
30 words
A method as in claim 8 wherein said silicon nitride layer has a thickness of approximately 1,000 Angstroms and said silicon dioxide layer has a thickness of approximately 1,000 Angstroms.
Claim 11
Dependent Claim
45 words
A method as in claim 1 wherein said protective structure includes a layer of polycrystalline silicon which is formed so that it overlies said gate oxide layer and a layer of silicon dioxide which is formed so that it overlies said layer of polycrystalline silicon.
Claim 12
Dependent Claim
32 words
A method as in claim 10 wherein said layer of polycrystalline silicon has a thickness of approximately 6,000 Angstroms and wherein said silicon dioxide layer has a thickness of approximately 3,000 Angstroms.
Claim 13
Dependent Claim
29 words
A method as in claim 1 wherein said first impurities are diffused through said opening in a dry atmosphere to minimize the growth of silicon dioxide during the diffusion.
Claim 14
Dependent Claim
32 words
A method as in claim 12 wherein said diffusion of said second impurity is carried out in a wet oxygen atmosphere to cause the formation of a thick layer of silicon dioxide.
Claim 15
Dependent Claim
33 words
A method as in claim 1 together with the step of depositing a layer of phosphorous-doped glass on the body and wherein said gate, source and drain contact metallization extends through the glass.
Claim 16
Dependent Claim
22 words
A method as in claim 1 wherein once said gate layer has been formed, it remains in place and is never removed.
Claim 17
Dependent Claim
54 words
A method as in claim 1 wherein said protective structure on said gate layer includes a layer of material different from the material of the gate layer and having etching properties different from that of the gate layer to permit formation of the channel in the desired location and with a controlled doping profile.
Claim 18
Dependent Claim
168 words
In a method for forming an MOS structure providing a semiconductor body of silicon having an impurity of one conductivity type and having a generally planar surface, forming a gate layer of silicon dioxide of relatively precise thickness on said surface, providing a protective structure on said gate layer, forming an opening in said protective structure adjacent said gate layer and exposing said surface, causing a first impurity to pass tHrough said opening utilizing an edge of said protective structure as a mask to provide a first region in said semiconductor body, forming an additional opening in said protective structure adjacent said gate layer and exposing said surface, causing a second impurity to pass through said first and second openings in said protective structure to cause the formation of second regions in said body with the second region in said first named opening being disposed in said first region to provide a channel of precise length underlying the gate layer and forming gate, source and drain contact metallization.
Claim 19
Dependent Claim
168 words
In a method for forming an MOS structure providing a semiconductor body of silicon having an impurity of one conductivity type and having a generally planar surface, forming a gate layer of silicon dioxide of relatively precise thickness on said surface, providing a protective structure on said gate layer, forming an opening in said protective structure adjacent said gate layer and exposing said surface, causing a first impurity to pass tHrough said opening utilizing an edge of said protective structure as a mask to provide a first region in said semiconductor body, forming an additional opening in said protective structure adjacent said gate layer and exposing said surface, causing a second impurity to pass through said first and second openings in said protective structure to cause the formation of second regions in said body with the second region in said first named opening being disposed in said first region to provide a channel of precise length underlying the gate layer and forming gate, source and drain contact metallization.
References Cited (Backward Citations)
US3670403A
Cited
US3793090A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |