US4056415A
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US
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Method for providing electrical isolating material in selected regions of a semiconductive material
Assignee: International Telephone and Telegraph Corp
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Filing: 1976-07-15
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Granted: 1977-11-01
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Expires: 1996-07-15
Abstract
Abstract An integrated circuit having dielectric isolation is fabricated by growing a double epitaxial layer of N-type semiconductive material onto a P-type substrate. A dielectric layer is formed over the epitaxial layer and thereafter the dielectric and a portion of the epitaxial growth are removed in selected isolation regions to expose the semiconductive material. A dielectric is formed by anodizing the N-type semiconductive material in the selected isolation regions to provide electrical isolation between the remaining portions of the epitaxial growth. Base and emitter elements are formed in the conventional manner to complete the integrated circuit which is thereafter packaged.
Inventors
- 👤 Charles R. Cook, Jr.
- 👤 Aung San U
- 👤 Raymond E. Scherrer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:11
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/66; H10P14/665; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10P90/191; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/014; H10W10/0142; H10W10/10; H10W10/17; H10W10/181; H10P14/6324; Y; Y10; Y10S; Y10S438/00; Y10S438/936
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
140 words
A method for providing electrical isolation regions in a semiconductive material, comprising the steps of: forming a protective layer on a surface of the semiconductive material; removing the protective layer in said regions to expose the semiconductive material; and forming a porous dielectric material from at least a portion of the semiconductive material in the regions by submerging the semiconductive material into an anodizing solution and applying and anodizing potential to the semiconductive material so that the exposed semiconductive material in the regions becomes an anode and is at least partially anodized to form the porous dielectric insulating material in the regions, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to a desired thickness.
Claim 2
Independent Claim
140 words
A method for providing electrical isolation regions in a semiconductive material, comprising the steps of: forming a protective layer on a surface of the semiconductive material; removing the protective layer in said regions to expose the semiconductive material; and forming a porous dielectric material from at least a portion of the semiconductive material in the regions by submerging the semiconductive material into an anodizing solution and applying and anodizing potential to the semiconductive material so that the exposed semiconductive material in the regions becomes an anode and is at least partially anodized to form the porous dielectric insulating material in the regions, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to a desired thickness.
Claim 3
Dependent Claim
48 words
A method as described in claim 1, additionally comprising the step of oxidizing the semiconductive material to form an oxide layer at the interface of the porous dielectric material and the semiconductive material to prevent impurities from being diffused into the semiconductive material through the porous dielectric material.
Claim 4
Dependent Claim
33 words
A method as described in claim 1, wherein the porous dielectric material is formed to a depth sufficient so that the porous dielectric material fills the regions and isolates the remaining semiconductive material.
Claim 5
Dependent Claim
29 words
A method as described in claim 1, additionally comprising the step of removing a portion of the semiconductive material in the regions prior to forming the porous dielectric material.
Claim 6
Dependent Claim
29 words
A method as described in claim 4, wherein the semiconductive material is removed by etching with an etch that attacks the semiconductive material more readily than the protective layer.
Claim 7
Dependent Claim
33 words
A method as described in claim 4, wherein the porous dielectric material is formed to a depth sufficient so that the porous dielectric material fills the regions and isolates the remaining semiconductive material.
Claim 8
Dependent Claim
58 words
A method as described in claim 1, wherein the semiconductive material comprises a substrate layer of a first semiconductivity type material and another layer formed thereon of a second semiconductivity type material, wherein the second semiconductivity type material in the regions is anodized to provide porous dielectric material between the remaining portions of the second semiconductivity type material.
Claim 9
Dependent Claim
38 words
A method as described in claim 7, additionally comprising the step of diffusing a first semiconductivity type dopant into and through the porous dielectric material to prevent subsequent inversion of the substrate layer to the second type conductivity.
Claim 10
Dependent Claim
48 words
A method as described in claim 8, additionally comprising the step of oxidizing the semiconductive material to form an oxide layer at the interface of the porous dielectric material and the semiconductive material to prevent impurities from being diffused into the semiconductive material through the porous dielectric material.
Claim 11
Dependent Claim
14 words
A method as described in claim 1, wherein the anodizing solution contains an acid.
Claim 12
Dependent Claim
25 words
A method as described in claim 1, wherein the anodizing solution contains an acid selected from a group including sulfuric, phosphoric, boric and nitric acids.
Claim 13
Dependent Claim
21 words
A method as described in claim 1, wherein excess porous dielectric material resulting from swell is removed using an etching solution.
Claim 14
Dependent Claim
32 words
A method as described in claim 1, wherein the anodizing potential is increased to a level at which the porous dielectric material electrically breaks down causing rapid anodization of the semiconductive material.
Claim 15
Dependent Claim
20 words
A method as described in claim 13, wherein the depth of anodization is controlled by the width of said regions.
Claim 16
Dependent Claim
24 words
A method as described in claim 1, wherein the anodizing solution is selected from a group of solutions including chlorox and ammonium borate solutions.
Claim 17
Dependent Claim
49 words
A method as described in claim 1, wherein the anodizing solution used is one that etches the dielectric material at a rate sufficient to form pores in said material to allow penetration of the anodizing solution into the dielectric material where it may react with the unanodized semiconductive material.
Claim 18
Independent Claim
219 words
A method of fabricating a semiconductor device comprising the steps of: forming on the surface of a body of semiconductive material of a first semiconductivity type a layer of second semiconductivity type material, said layer having a high concentration of impurities on a side adjacent the body and a lower concentration on a side opposite said body; forming a protective layer on said layer of second semiconductivity type material; removing said protective layer from selected regions to expose the semiconductive material; forming a porous dielectric material from at least a portion of the semiconductive material in the selected regions by submerging said device in an anodizing solution and applying an anodizing potential to the semiconductive material in the regions so that the exposed semiconductive material becomes an anode and is at least partially anodized to form the porous dielectric insulation in the regions, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to a desired thickness; removing said device from the anodizing solution; forming regions of first semiconductivity type material in the layer of second semiconductivity type material; and forming zones of second type semiconductivity material in said regions of first type semiconductivity material.
Claim 19
Independent Claim
219 words
A method of fabricating a semiconductor device comprising the steps of: forming on the surface of a body of semiconductive material of a first semiconductivity type a layer of second semiconductivity type material, said layer having a high concentration of impurities on a side adjacent the body and a lower concentration on a side opposite said body; forming a protective layer on said layer of second semiconductivity type material; removing said protective layer from selected regions to expose the semiconductive material; forming a porous dielectric material from at least a portion of the semiconductive material in the selected regions by submerging said device in an anodizing solution and applying an anodizing potential to the semiconductive material in the regions so that the exposed semiconductive material becomes an anode and is at least partially anodized to form the porous dielectric insulation in the regions, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to a desired thickness; removing said device from the anodizing solution; forming regions of first semiconductivity type material in the layer of second semiconductivity type material; and forming zones of second type semiconductivity material in said regions of first type semiconductivity material.
Claim 20
Dependent Claim
23 words
A method as described in claim 17, additionally comprising the step of encapsulating said body and providing electrical connections to desired portions thereof.
Claim 21
Dependent Claim
54 words
A method as described in claim 17, wherein the step of forming a layer of second semiconductivity type material comprises the steps of forming a first layer of second semiconductivity type material having a high concentration of impurities and forming a second layer of second semiconductivity type material having a lower concentration of impurities.
Claim 22
Dependent Claim
63 words
A method as described in claim 17, wherein the step of forming a layer of second semiconductivity type material comprises the step of growing an eptiaxial layer of second semiconductivity type material in such a manner as to provide a varying concentration of impurities from a high concentration adjacent the body to a lower concentration at an opposite side remote from said body.
Claim 23
Dependent Claim
44 words
A method as described in claim 17, additionally comprising the step of oxidizing said semiconductive material to form a non-porous oxide layer at the interface of the porous dielectric insulation and the semiconductive material to prevent impurities from being diffused into the semiconductive material.
Claim 24
Dependent Claim
41 words
A method as described in claim 17, wherein all of the second semiconductivity type material in the second layer is anodized in the selected regions to form the porous dielectric material and isolate the remaining portions of second semiconductivity type material.
Claim 25
Dependent Claim
22 words
A method as described in claim 17, additionally comprising removing a portion of the semiconductive material in said regions prior to anodizing.
Claim 26
Dependent Claim
41 words
A method as described in claim 17, additionally comprising the step of diffusing a first type of semiconductive impurity into and through the porous dielectric insulation to prevent inversion of the body of semiconductive material to the second type of semiconductivity.
Claim 27
Dependent Claim
33 words
A method as described in claim 24, additionally comprising the step of oxidizing the semiconductive material thereby forming an oxide layer at the interface of the porous dielectric insulation and the semiconductive material.
Claim 28
Dependent Claim
23 words
A method as described in claim 24, additionally comprising the step of encapsulating said body and providing electrical connections to desired portions thereof.
Claim 29
Dependent Claim
36 words
A method as described in claim 17, wherein the regions of first semiconductivity type material and the zones of second type semiconductive material are formed prior to forming the porous dielectric material in the selected regions.
Claim 30
Dependent Claim
35 words
A method as described in claim 17, wherein the regions of first semiconductivity type material and the zones of second type semiconductive material are formed after forming the porous dielectric material in the selected regions.
Claim 31
Dependent Claim
32 words
A method as described in claim 19, wherein the anodizing potential is increased to a level at which the porous dielectric material electrically breaks down causing rapid anodization of the semiconductive material.
Claim 32
Dependent Claim
21 words
A method as described in claim 29, wherein the depth of anodization is controlled by the width of the selected regions.
Claim 33
Dependent Claim
19 words
A method as described in claim 17, additionally comprising the step of removing excess porous dielectric insulation by etching.
Claim 34
Dependent Claim
14 words
A method as described in claim 17, wherein the anodizing solution contains an acid.
Claim 35
Dependent Claim
25 words
A method as described in claim 17, wherein the anodizing solution contains an acid selected from a group including sulfuric, phosphoric, boric and nitric acids.
Claim 36
Dependent Claim
24 words
A method as described in claim 17, wherein the anodizing solution is selected from a group of solutions including chlorox and ammonium borate solutions.
Claim 37
Dependent Claim
49 words
A method as described in claim 17, wherein the anodizing solution used is one that etches the dielectric material at a rate sufficient to form pores in said material to allow penetration of the anodizing solution into the dielectric material where it may react with the unanodized semiconductive material.
Claim 38
Independent Claim
87 words
A method for providing electrical isolation regions in a semiconductive material, comprising the step of: forming a porous dielectric material from at least a portion of the semiconductive material in the regions by anodizing at least a portion of the semiconductive material in the regions in an anodizing solution, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to any desired thickness.
Claim 39
Independent Claim
87 words
A method for providing electrical isolation regions in a semiconductive material, comprising the step of: forming a porous dielectric material from at least a portion of the semiconductive material in the regions by anodizing at least a portion of the semiconductive material in the regions in an anodizing solution, the porosity of said dielectric material being sufficient to allow the anodizing solution to penetrate the dielectric and react with the unanodized semiconductive material in said regions, whereby the isolation regions may be formed to any desired thickness.
Claim 40
Dependent Claim
26 words
A method as described in claim 36, wherein an anodizing potential is applied at a level that causes the porous dielectric material to break down electrically.
Claim 41
Dependent Claim
49 words
A method as described in claim 36, wherein the anodizing solution used is one that etches the dielectric material at a rate sufficient to form pores in said material to allow penetration of the anodizing solution into the dielectric material where it may react with the unanodized semiconductive material.
Claim 42
Dependent Claim
31 words
A method as described in claim 38, wherein the anodizing solution is selected from a group of solutions including sulfuric acid, phosphoric acid, boric acid, nitric acid, clorox and ammonium borate.
References Cited (Backward Citations)
US3354360A
Cited
US3442011A
Cited
US3534234A
Cited
US3649386A
Cited
US3640806A
Cited
US3648125A
Cited
US3861968A
Cited
US3919060A
Cited
US3954523A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-31 | 1981-05-02 | 1981-11-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-31 | 1985-05-02 | 1985-11-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-31 | 1989-05-02 | 1989-11-01 | $7700.00 | Window Closed / Lapsed |