Patent US4554059A successfully refreshed from Google Patents.
US4554059A
Expired / Lapsed
US
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Electrochemical dielectric isolation technique
Assignee: Intersil Corp
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Filing: 1984-12-04
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Granted: 1985-11-19
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Expires: 2004-12-04
Abstract
Abstract Plane indicating moats are formed extending through an epitaxial layer into a substrate simultaneous with the formation of the isolation moats which terminate within the epitaxial layer. The substrate is ground to a predetermined thickness after formation of the dielectric isolation and support structure. The composite structure is inserted in an etchant with conditions set to electrochemically etch only the substrate. The exposed plane indicating moats are used as a reference for a final polishing step.
Inventors
- 👤 John P. Short
- 👤 Craig J. McLachlan
- 👤 Charles Messmer
- 👤 Paul S. Reinecke
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 18:08
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/019; H10W10/10
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
173 words
A method of fabricating dielectrically isolated islands including: forming a second layer of semiconductor material on a first layer of semiconductor material, said first layer having a lower resistivity than said second layer; etching said second layer to form first moats extending down from a first surface of said second layer and terminating in said first layer and second moats extending down from said first surface and terminating within said second layer; forming a dielectric layer on said first surface of said second layer and said moats; forming a support layer on said dielectric layer resulting in a composite structure; continuously moving said composite structure into an etchant bath and biasing said first layer and said bath to electrochemically etch said first layer to its interface with said second layer and said dielectric layer of said first moats; and polishing said second layer and said dielectric layer down to a plane which exposes said support layer in said first and second moats using exposed portions of said first moats as a reference plane.
Claim 2
Independent Claim
173 words
A method of fabricating dielectrically isolated islands including: forming a second layer of semiconductor material on a first layer of semiconductor material, said first layer having a lower resistivity than said second layer; etching said second layer to form first moats extending down from a first surface of said second layer and terminating in said first layer and second moats extending down from said first surface and terminating within said second layer; forming a dielectric layer on said first surface of said second layer and said moats; forming a support layer on said dielectric layer resulting in a composite structure; continuously moving said composite structure into an etchant bath and biasing said first layer and said bath to electrochemically etch said first layer to its interface with said second layer and said dielectric layer of said first moats; and polishing said second layer and said dielectric layer down to a plane which exposes said support layer in said first and second moats using exposed portions of said first moats as a reference plane.
Claim 3
Dependent Claim
39 words
The method according to claim 1 wherein said second moats are etched to terminate within said second layer a sufficient distance from said first and second layer interface so as not to be exposed by said electrochemical etch step.
Claim 4
Dependent Claim
49 words
The method according to claim 1 wherein said first moats are formed to have a depth within and lateral spacing in said first layer to prevent electrochemical etching of said second layer to a depth from said interface below a plane formed by the terminations of said second moats.
Claim 5
Dependent Claim
15 words
The method according to claim 1 wherein said moats are formed by an anisotropic etch.
Claim 6
Dependent Claim
27 words
The method according to claim 4 wherein said first moat is etched to a depth less than a V-out depth so as to have a flat termination.
Claim 7
Dependent Claim
20 words
The method according to claim 1 including removing portion of said first layer to reduce its thickness before electrochemical etching.
Claim 8
Dependent Claim
15 words
The method according to claim 1 wherein said second layer is formed by epitaxial deposition.
Claim 9
Dependent Claim
41 words
The method according to claim 1 including introducing impurities of the same conductivity type as said second layer into said first surface of said second layer to form regions of reduced resistivity in said second layer before forming said support layer
Claim 10
Dependent Claim
65 words
The method according to claim 1 including introducing impurities of a second conductivity type opposite a first conductivity type of said second layer into selective areas of said first surface of said second layer to form regions of said second conductivity type extending from said first surface of said second layer to said interface of said first and second layers before forming said support layer.
Claim 11
Dependent Claim
40 words
The method according to claim 9 including introducing impurities of said first conductivity type into selected areas of said first surface of said second layer to form regions of reduced resistivity in said second layer before forming said support layer.
Claim 12
Dependent Claim
18 words
The method according to claim 1 including removing portions of said support layer to produce a planar surface.
Claim 13
Dependent Claim
41 words
The method according to claim 1 wherein said composite structure is moved into said etchant bath with an exposed surface of said second layer forming an angle of less than 20 degrees with respect to the surface of said etchant bath.
Claim 14
Dependent Claim
41 words
The method according to claim 12 wherein said composite structure is moved into said etchant bath with said exposed surface of said second layer at an angle of less than 20 degrees with respect to the surface of said etchant bath.
Claim 15
Dependent Claim
52 words
The method according to claim 1 including etching said first surface of said second layer to form a well extending from said first surface to said interface between said first and second layers, filling said well with a semiconductor material having different characteristics than said second layer before forming said support layer.
Claim 16
Dependent Claim
32 words
The method according to claim 14 wherein said well filling step includes epitaxial deposition of a semiconductor material having a second conductivity type opposite a first conductivity type of said second layer.
Claim 17
Dependent Claim
40 words
The method according to claim 14 wherein said well filling step includes epitaxial deposition of semiconductor material having the same conductivity type as said second layer and a lower resistivity than said second layer and higher than said first layer.
Claim 18
Dependent Claim
32 words
The method according to claim 1 wherein said composite structur is moved into said etchant bath slow enough so that the electrochemical etching will terminate before all the first layer is etched.
Claim 19
Dependent Claim
26 words
The method according to claim 1 wherein said first moats are formed to have a lateral spacing sufficiently close to prevent etching of said second layer.
Claim 20
Independent Claim
141 words
A method of fabricating dielectrically isolated islands including: forming a second layer of semiconductor material on a first layer of semiconductor material, said first layer having a lower resistivity than said second layer; etching said second layer to form first moats extending down from a first surface of said second layer to a first depth and terminating in said first layer and to form second moats extending down from said first surface to a second depth less than said first depth; forming a dielectric layer on said first surface of said second layer and said moats; forming a support layer on said dielectric layer resulting in a composite structure; and continuously moving said composite structure into an etchant bath and biasing said first layer and said bath to electrochemically etch said first layer to said dielectric layer of said first moats.
Claim 21
Independent Claim
141 words
A method of fabricating dielectrically isolated islands including: forming a second layer of semiconductor material on a first layer of semiconductor material, said first layer having a lower resistivity than said second layer; etching said second layer to form first moats extending down from a first surface of said second layer to a first depth and terminating in said first layer and to form second moats extending down from said first surface to a second depth less than said first depth; forming a dielectric layer on said first surface of said second layer and said moats; forming a support layer on said dielectric layer resulting in a composite structure; and continuously moving said composite structure into an etchant bath and biasing said first layer and said bath to electrochemically etch said first layer to said dielectric layer of said first moats.
Claim 22
Dependent Claim
41 words
The method according to claim 19 including removing said second layer and said dielectric layer down to a plane which exposes said support layer in said first and second moats using exposed portions of said first moats as a reference plane.
Claim 23
Independent Claim
109 words
A method of fabricating dielectrically isolated islands including; etching a substrate of semiconductor material to form first moats extending down from a first surface and terminating at a first depth and to form second moats extending down from said first surface and terminating at a second depth less than said first depth; forming a dielectric layer on said first surface of said substrate and said moats; forming a support layer on said dielectric layer resulting in a composite structure; and continuously moving said composite structure into an etchant bath and biasing said substrate and said bath to electrochemically etch said substrate to said dielectric layer of said first moats.
Claim 24
Independent Claim
109 words
A method of fabricating dielectrically isolated islands including; etching a substrate of semiconductor material to form first moats extending down from a first surface and terminating at a first depth and to form second moats extending down from said first surface and terminating at a second depth less than said first depth; forming a dielectric layer on said first surface of said substrate and said moats; forming a support layer on said dielectric layer resulting in a composite structure; and continuously moving said composite structure into an etchant bath and biasing said substrate and said bath to electrochemically etch said substrate to said dielectric layer of said first moats.
Claim 25
Dependent Claim
40 words
The method according to claim 21 including removing said substrate and said dielectric layer down to a plane which exposes said support layer in said first and second moats using exposed portions of said first moats as a reference plane.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-11-18 | 1989-05-20 | 1989-11-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-18 | 1993-05-20 | 1993-11-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-18 | 1997-05-20 | 1997-11-19 | $7700.00 | Window Closed / Lapsed |