US5432121A
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Method for fabricating a multilayer epitaxial structure
Assignee: GI Corp
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Filing: 1994-05-16
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Granted: 1995-07-11
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Expires: 2014-05-16
Abstract
Abstract An all epitaxial process performed entirely in a CVD reactor is employed to grow epitaxial layers with accurately controlled successively low and high dopant concentrations over a heavily doped substrate, eliminating the need for a separate diffusion, even for high purity concentrations. After purging the reactor system, the heavily doped silicon substrate is "capped" by growing two successive very thin silicon sublayers of the same conductivity type. The reactor chamber is subjected to a hydrogen purge to deplete any contaminents after each sublayer is formed. The cap sublayers form a narrow, abrupt intrinsic transition region with the substrate and become an active part of the device structure. A lightly doped epitaxial layer is grown over the "capped" substrate so that a depletion region can be formed in the device under suitable reverse bias. A heavily doped epitaxial layer is then grown over the lightly doped epitaxial layer. The heavily doped epitaxial layer forms a contact layer and has a polarity opposite to that of the substrate.
Inventors
- 👤 Joseph Chan
- 👤 Dennis Garbis
- 👤 Lawrence Laterza
- 👤 Gregory Zakaluk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 08:58
CPC Classifications
H; H10; H10P; H10P32/00; H10P32/10; H10P32/15; Y; Y10; Y10S; Y10S148/00; Y10S148/041
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
134 words
An all epitaxial method of fabricating a multilayer structure in a continuous process in a CVD reactor chamber comprising the steps of: (a) positioning a heavily doped silicon substrate of a first conductivity type on a susceptor in the reactor chamber; (b) heating the chamber; (c) purging the reactor chamber to deplete contaminents therein; (d) growing a doped first silicon sublayer over the substrate; (e) purging the reactor chamber to deplete contaminents therein; (f) growing a doped second silicon sublayer over said first sublayer; (g) purging the reactor to deplete any contaminents therein; (h) growing a lightly doped first epitaxial layer above the second silicon sublayer; and (i) growing a heavily doped second epitaxial layer above the first epitaxial layer, the second epitaxial layer having a conductivity type opposite to that of the substrate.
Claim 2
Dependent Claim
134 words
An all epitaxial method of fabricating a multilayer structure in a continuous process in a CVD reactor chamber comprising the steps of: (a) positioning a heavily doped silicon substrate of a first conductivity type on a susceptor in the reactor chamber; (b) heating the chamber; (c) purging the reactor chamber to deplete contaminents therein; (d) growing a doped first silicon sublayer over the substrate; (e) purging the reactor chamber to deplete contaminents therein; (f) growing a doped second silicon sublayer over said first sublayer; (g) purging the reactor to deplete any contaminents therein; (h) growing a lightly doped first epitaxial layer above the second silicon sublayer; and (i) growing a heavily doped second epitaxial layer above the first epitaxial layer, the second epitaxial layer having a conductivity type opposite to that of the substrate.
Claim 3
Dependent Claim
33 words
The method of claim 1 wherein the step of growing a first silicon sublayer comprises the step of growing the first silicon sublayer with a conductivity type opposite to that of the substrate.
Claim 4
Dependent Claim
38 words
The method of claim 1 wherein the step of growing a second silicon sublayer comprises the step of growing the second silicon sublayer with a conductivity type the same as the conductivity type of the first silicon sublayer.
Claim 5
Dependent Claim
34 words
The method of claim 1 wherein the step of growing a first silicon sublayer comprises the step of growing the first silicon sublayer with a conductivity type which is the same as the substrate.
Claim 6
Dependent Claim
38 words
The method of claim 4 wherein the step of growing a second silicon sublayer comprises the step of growing the second silicon sublayer with a conductivity type the same as the conductivity type of the first silicon sublayer.
Claim 7
Dependent Claim
32 words
The method of claim 1 wherein the step of growing the first silicon sublayer comprises the step of growing the first silicon sublayer to a thickness of approximately one to two microns.
Claim 8
Dependent Claim
32 words
The method of claim 1 wherein the step of growing the second silicon sublayer comprises the step of growing the second silicon sublayer to a thickness of approximately one to two microns.
Claim 9
Dependent Claim
40 words
The method of claim 1 wherein the step of growing the second silicon sublayer comprises the step of growing the second silicon sublayer to have a resistivity which is approximately the same as the resistivity of the first silicon sublayer.
Claim 10
Dependent Claim
37 words
The method of claim 1 wherein the step of growing the second silicon sublayer comprises the step of growing the second silicon sublayer to have a resistivity approximately equal to the resistivity of the first epitaxial layer.
Claim 11
Dependent Claim
28 words
The method of claim 1 wherein the step of positioning the substrate comprises employing a substrate which has a resistivity of equal to or less than 0.005 ohm-cm.
Claim 12
Dependent Claim
30 words
The method of claim 9 wherein the step of positioning the substrate comprises employing a substrate which has a resistivity equal to or less than 0.002 ohm-cm for P-type material.
Claim 13
Dependent Claim
36 words
The method of claim 1 wherein the step of growing the first epitaxial layer comprises the step of growing the first epitaxial layer in a hydrogen ambient at a temperature between 1000° C. and 1200° C.
Claim 14
Dependent Claim
31 words
The method of claim 1 wherein the step of growing the first epitaxial layer comprises the step of growing the first epitaxial layer with a resistivity of less than 100 ohm-cm.
Claim 15
Dependent Claim
31 words
The method of claim 1 wherein the step of growing the second epitaxial layer comprises the step of growing the second epitaxial layer with a resistivity of less than 0.005 ohm-cm.
Claim 16
Dependent Claim
30 words
The method of claim 1 wherein the step of growing the second epitaxial layer comprises the step of growing the second epitaxial layer with a thickness of approximately 40 microns.
Claim 17
Dependent Claim
31 words
The method of claim 1 wherein the step of growing the first epitaxial layer comprises the step of growing the first epitaxial layer with a thickness of up to 150 microns.
Claim 18
Dependent Claim
34 words
The method of claim 1 wherein the step of growing the first epitaxial layer comprises the step of growing the first epitaxial layer to have the same conductivity type as the first silicon sublayer.
Claim 19
Dependent Claim
17 words
The method of claim 1 wherein the multilayer structure forms a base material for a semiconductor device.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-07-10 | 1999-01-09 | 1999-07-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-07-10 | 2003-01-09 | 2003-07-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-07-10 | 2007-01-09 | 2007-07-11 | $7700.00 | Window Closed / Lapsed |