US3607469A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of obtaining low concentration impurity predeposition on a semiconductive wafer
Assignee: National Semiconductor Corp
•
Filing: 1969-03-27
•
Granted: 1971-09-21
•
Expires: 1989-03-27
Abstract
Abstract A method for predepositing very low concentrations of impurity on a semiconductive wafer essentially comprising the steps of immersing the wafer in a nonoxidizing acid solution to remove the oxide from predetermined surface areas of the chip to render those areas highly reactive, and immersing the wafer into an oxidizing solution having a controlled concentration of impurity material therein to cause a new layer of impurity impregnated oxide to be grown over the preselected surface areas. The wafer may then be heated in a diffusion oven to cause the predeposited impurities to be driven from the oxide into the surface of the wafer.
Inventors
- 👤 Lee P Madden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:49
CPC Classifications
H; H10; H10P; H10P95/00; H10D; H10D99/00; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
27 words
A method as recited in claim 1 wherein the concentration of semiconductor impurities in said oxidizing solution is less than 1 X 1016 atoms per cubic centimeter.
Claim 2
Dependent Claim
22 words
A method as recited in claim 1 wherein said selected area is subjected to said oxidizing solution from 2 to 10 minutes.
Claim 3
Dependent Claim
33 words
A method as recited in claim 1 wherein the concentration of semiconductor impurities in said oxidizing solution is within the range of 1 X 1015 to 1 X 1018 atoms per cubic centimeter.
Claim 4
Independent Claim
107 words
A method of obtaining a low concentration predeposition of impurity atoms on a selected surface area of a silicon wafer at room temperature, comprising the steps of: coating the entire surface of the wafer with a layer of substantially pure oxide; removing the portion of the substantially pure oxide layer overlying said selected surface area to expose said selected surface area; and subjecting said selected surface area to an oxidizing solution having a predetermined concentration of impurities therein for a predetermined period of time to cause a doped oxide layer to be nonanodically grown over said selected surface area having said predetermined concentration of impurities suspended therein.
Claim 5
Dependent Claim
52 words
A method as recited in claim 5 in which the substantially pure oxide layer portion overlying said selected surface area is removed by submerging in an acid solution and in which said selected surface area so exposed is rinsed and cleaned in deionized water prior to being subjected to said oxidizing solution.
Claim 6
Dependent Claim
26 words
A method as recited in claim 6 wherein the concentration of impurities in saId oxidizing solution is less than 1 X 1016 atoms per cubic centimeter.
Claim 7
Dependent Claim
20 words
A method as recited in claim 5 wherein said oxidizing solution is a mixture of antimony trioxide and sulfuric acid.
Claim 8
Dependent Claim
20 words
A method as recited in claim 5 wherein said oxidizing solution is a mixture of phosphoric acid and nitric acid.
Claim 9
Dependent Claim
23 words
A method as recited in claim 7 wherein said silicon wafer is subjected to said oxidizing solution for from 2 to 10 minutes.
Claim 10
Dependent Claim
33 words
A method as recited in claim 5 wherein said predetermined concentration of impurities in said oxidizing solution is in the range from 1 X 1015 to 1 X 1018 atoms per cubic centimeter.
Claim 11
Dependent Claim
121 words
In the process for producing field effect transistors, each having a source region and a drain region defining a channel region therebetween which underlies a gate electrode, the improvement of doping the channel region comprising the steps of: exposing only the channel region of the otherwise substantially pure oxide coated transistor by cutting a window into the oxide; subjecting the exposed channel region to an oxidizing solution, having a predetermined concentration of impurities therein, for a predetermined period of time to cause the nonanodic formation of an impurity doped oxide layer over the channel region; and heating said transistor for a predetermined period of time to cause the impurities from said impurity-doped oxide layer to diffuse into the underlying channel region.
Claim 12
Dependent Claim
26 words
A method as recited in claim 12 wherein the concentration of impurities in said oxidizing solution is less than 1 X 1016 atoms per cubic centimeter.
Claim 13
Dependent Claim
22 words
A method as recited in claim 12 wherein said channel region is subjected to said oxidizing solution from 2 to 10 minutes.
Claim 14
Dependent Claim
20 words
A method as recited in claim 12 wherein said oxidizing solution is a mixture of antimony trioxide and sulfuric acid.
Claim 15
Dependent Claim
20 words
A method as recited in claim 12 wherein said oxidizing solution is a mixture of phosphoric acid and nitric acid.
Claim 16
Dependent Claim
29 words
A method as recited in claim 12 wherein the impurities in said oxidizing solution are selected from the group consisting of antimony, phosphorous, gallium, boron, aluminum, bismuth and indium.
Claim 17
Dependent Claim
33 words
A method as recited in claim 12 wherein the predetermined concentration of impurities in said oxidizing solution is in the range from 1 X 1015 to 1 X 1018 atoms per cubic centimeter.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |