Patent US4902633A successfully refreshed from Google Patents.
US4902633A
Expired / Lapsed
US
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Process for making a bipolar integrated circuit
Assignee: NXP USA Inc
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Filing: 1988-05-09
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Granted: 1990-02-20
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Expires: 2008-05-09
Abstract
Abstract A bipolar integrated circuit requiring less silicon area is provided by the use of a three layer epitaxy on top of a substrate. The first epitaxial layer is of the same conductivity type as the substrate and adds additional height to the substrate surrounding the buried layer. The buried layer serves as a collector and it is surrounded by an isolation area. The top two epitaxial layers are of a conductivity type opposite to that of the substrate with the upper most epitaxial layer having a higher dopant density than does the middle epitaxial layer. A master mask is used to provide self-alignment between the isolation area, a collector plug which makes contact to the buried layer, and a base region.
Inventors
- 👤 Bertrand F. Cambou
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:33
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/13; H10D62/137; H10D62/17; H10D62/60; H10W; H10W10/00; H10W10/01; H10W10/031; H10W10/30; H10W15/00; H10W15/01; Y; Y10; Y10S; Y10S148/00; Y10S148/011; Y10S148/037
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
166 words
A process for making a bipolar integrated circuit, comprising: providing a substrate of a first conductivity type and having a first surface; selectively forming a buried layer of a second conductivity type in the substrate and extending from the first surface; providing a first epitaxial layer of the first conductivity type over the first surface; providing a second epitaxial layer of the second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer and having a higher dopant concentration than the second epitaxial layer; selectively providing a dopant of the first conductivity type in the third epitaxial layer in a manner to surround the buried layer; selectively providing a dopant of the second conductivity type in the third epitaxial layer and positioned over a portion of the buried layer; and performing a diffusion to drive in the dopants selectively provided in the third epitaxial layer and simultaneously causing the buried layer to diffuse upwards.
Claim 2
Dependent Claim
166 words
A process for making a bipolar integrated circuit, comprising: providing a substrate of a first conductivity type and having a first surface; selectively forming a buried layer of a second conductivity type in the substrate and extending from the first surface; providing a first epitaxial layer of the first conductivity type over the first surface; providing a second epitaxial layer of the second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer and having a higher dopant concentration than the second epitaxial layer; selectively providing a dopant of the first conductivity type in the third epitaxial layer in a manner to surround the buried layer; selectively providing a dopant of the second conductivity type in the third epitaxial layer and positioned over a portion of the buried layer; and performing a diffusion to drive in the dopants selectively provided in the third epitaxial layer and simultaneously causing the buried layer to diffuse upwards.
Claim 3
Dependent Claim
38 words
The process of claim 1 further including selectively providing a base well of the first conductivity type in the third epitaxial layer over a portion of the buried layer and providing an emitter area in the base well.
Claim 4
Dependent Claim
25 words
The process of claim 1 wherein the dopant concentration in the third epitaxial layer is approximately twice the dopant concentration in the second epitaxial layer.
Claim 5
Dependent Claim
34 words
The process of claim 1 wherein the selectively provided dopant of the first conductivity extends to the first epitaxial layer and the selectively provided dopant of the second conductivity extends to the buried layer.
Claim 6
Independent Claim
249 words
A method for making an integrated circuit, comprising: providing a substrate of a first conductivity type and having a first surface; providing a dopant of a second conductivity type into the substrate and extending from the first surface; providing a first epitaxial layer of the first conductivity type over the first surface; providing a second epitaxial layer of the second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer, the third epitaxial layer being of a dopant concentration higher than the second epitaxial layer; providing a layer of oxide over the third epitaxial layer; providing a dielectric layer over the layer of oxide; using a master mask to selectively provide openings in the dielectric layer for an isolation region, a collector plug, and a base region; etching thru the oxide in the opening provided for the isolation region and providing a dopant of the first conductivity; masking over all the openings except the opening for the collector plug; etching through the oxide in the collector plug opening and providing a dopant of the second conductivity type in the collector plug opening; diffusing the dopants in the isolation region, in the collector plug, and in the buried layer; masking over all the openings except for the base region opening; forming a base region of the first conductivity type through the base region opening; and forming an emitter area of the second conductivity type in the base region.
Claim 7
Independent Claim
249 words
A method for making an integrated circuit, comprising: providing a substrate of a first conductivity type and having a first surface; providing a dopant of a second conductivity type into the substrate and extending from the first surface; providing a first epitaxial layer of the first conductivity type over the first surface; providing a second epitaxial layer of the second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer, the third epitaxial layer being of a dopant concentration higher than the second epitaxial layer; providing a layer of oxide over the third epitaxial layer; providing a dielectric layer over the layer of oxide; using a master mask to selectively provide openings in the dielectric layer for an isolation region, a collector plug, and a base region; etching thru the oxide in the opening provided for the isolation region and providing a dopant of the first conductivity; masking over all the openings except the opening for the collector plug; etching through the oxide in the collector plug opening and providing a dopant of the second conductivity type in the collector plug opening; diffusing the dopants in the isolation region, in the collector plug, and in the buried layer; masking over all the openings except for the base region opening; forming a base region of the first conductivity type through the base region opening; and forming an emitter area of the second conductivity type in the base region.
Claim 8
Dependent Claim
11 words
The method of claim 5 wherein the dielectric is silicon nitride.
Claim 9
Dependent Claim
31 words
The method of claim 5 wherein forming the base region includes etching through the oxide in the base region opening and implanting dopants and diffusing the dopants in the base region.
Claim 10
Independent Claim
234 words
A method of providing a bipolar integrated circuit, comprising: providing a substrate having a first surface and being of a first conductivity type; selectively providing a buried layer of a second conductivity type and having a dopant concentration of approximately 5×10 18 atoms per cubic centimeter, the buried layer being provided in the substrate; providing a first epitaxial layer of a first conductivity type over the first surface; providing a second epitaxial layer of a second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer, the third epitaxial layer having a dopant concentration nearly twice the dopant concentration of the second epitaxial layer; selectively providing dopants in the third epitaxial layer of the first conductivity type for an isolation area; selectively providing dopants of the second conductivity type in the third epitaxial layer for a collector plug; diffusing the selectively provided dopants to form an isolation area having a dopant concentration of approximately 2×10 19 atoms per cubic centimeter and to form a collector plug having a dopant concentration of approximately 5×10 19 atoms per cubic centimeter and extending thru the third and second epitaxial layers to contact the buried layer; selectively forming a base area having dopant concentration of the first conductivity type of approximately 5×10 18 atoms per cubic centimeter; and forming an emitter area in the base area.
Claim 11
Independent Claim
234 words
A method of providing a bipolar integrated circuit, comprising: providing a substrate having a first surface and being of a first conductivity type; selectively providing a buried layer of a second conductivity type and having a dopant concentration of approximately 5×10 18 atoms per cubic centimeter, the buried layer being provided in the substrate; providing a first epitaxial layer of a first conductivity type over the first surface; providing a second epitaxial layer of a second conductivity type over the first epitaxial layer; providing a third epitaxial layer of the second conductivity type over the second epitaxial layer, the third epitaxial layer having a dopant concentration nearly twice the dopant concentration of the second epitaxial layer; selectively providing dopants in the third epitaxial layer of the first conductivity type for an isolation area; selectively providing dopants of the second conductivity type in the third epitaxial layer for a collector plug; diffusing the selectively provided dopants to form an isolation area having a dopant concentration of approximately 2×10 19 atoms per cubic centimeter and to form a collector plug having a dopant concentration of approximately 5×10 19 atoms per cubic centimeter and extending thru the third and second epitaxial layers to contact the buried layer; selectively forming a base area having dopant concentration of the first conductivity type of approximately 5×10 18 atoms per cubic centimeter; and forming an emitter area in the base area.
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