US5262345A
Expired / Lapsed
US
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Complimentary bipolar/CMOS fabrication method
Assignee: Analog Devices Inc
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Filing: 1992-05-15
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Granted: 1993-11-16
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Expires: 2012-05-15
Abstract
Abstract A complementary bipolar process enables both PNP and NPN transistors to be added to a CMOS process with a minimum of extra fabrication steps. The P-well of a CMOS process is used for the collector region of the PNP transistor and the "down isolation" for the NPN transistor. A buried P diffusion provides "up" isolation for the NPN transistor and buried collector for the PNP transistor. A method for increasing the NPN buried collector to "up" isolation breakdown voltage is described which uses multiple N type impurities.
Inventors
- 👤 Mohammad S. Nasser
- 👤 Saurabh M. Desai
- 👤 Derek F. Bowers
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 00:15
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/40; H10D84/401; H10D10/00; H10D10/40; H10D10/421; H10D10/60; H10D84/01; H10D84/0107; H10D84/0109; H10D84/02; H10D84/03; H10D84/038; H10W; H10W10/00; H10W10/01; H10W10/031; H10W10/30; H10W15/00; H10W15/01; Y; Y10; Y10S; Y10S148/00; Y10S148/009
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
172 words
A method of forming complementary PNP and NPN bipolar transistors simultaneously with complementary P-channel and N-channel metal oxide semiconductor (CMOS) transistors on a common substrate with an N-type epitaxial layer, comprising: forming a first P-well for an N-channel MOS transistor, a second P-well for an NPN bipolar transistor and a collector well for a PNP bipolar transistor layer by a common diffusion of P-type dopant into said epitaxial layer, forming an N-base and a P-emitter within said collector well for the PNP bipolar transistor, forming a source and drain for said P-channel MOS transistor within said epitaxial layer in a common diffusion of P-type dopant with the emitter of said PNP bipolar transistor, forming a P-base, N-emitter and N-collector within said second P-well for said NPN bipolar transistor, said second P-well isolating said NPN bipolar transistor from other devices on said substrate, and forming a source and drain within said first P-well for said N-channel MOS transistor in a common diffusion of N-type dopant with the emitter of said NPN bipolar transistor.
Claim 2
Independent Claim
172 words
A method of forming complementary PNP and NPN bipolar transistors simultaneously with complementary P-channel and N-channel metal oxide semiconductor (CMOS) transistors on a common substrate with an N-type epitaxial layer, comprising: forming a first P-well for an N-channel MOS transistor, a second P-well for an NPN bipolar transistor and a collector well for a PNP bipolar transistor layer by a common diffusion of P-type dopant into said epitaxial layer, forming an N-base and a P-emitter within said collector well for the PNP bipolar transistor, forming a source and drain for said P-channel MOS transistor within said epitaxial layer in a common diffusion of P-type dopant with the emitter of said PNP bipolar transistor, forming a P-base, N-emitter and N-collector within said second P-well for said NPN bipolar transistor, said second P-well isolating said NPN bipolar transistor from other devices on said substrate, and forming a source and drain within said first P-well for said N-channel MOS transistor in a common diffusion of N-type dopant with the emitter of said NPN bipolar transistor.
Claim 3
Dependent Claim
37 words
The method of claim 1, wherein a P-type isolation barrier is formed in the epitaxial layer around the NPN bipolar transistor in a diffusion of P-type dopant which is common with said P-well and collector well diffusion.
Claim 4
Dependent Claim
47 words
The method of claim 1, wherein a guard ring for the N-channel MOS transistor and the base of the NPN bipolar transistor are formed by a common diffusion of P-type dopant; and the emitter of the NPN bipolar transistor is formed within the base of that transistor.
Claim 5
Dependent Claim
25 words
The method of claim 1, wherein the dopant concentration in the P-well and collector well are not more than about 10 16 ions/cm 3 .
References Cited (Backward Citations)
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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) | 1996-11-15 | 1997-05-17 | 1997-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-11-15 | 2001-05-17 | 2001-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-11-15 | 2005-05-17 | 2005-11-16 | $7700.00 | Window Closed / Lapsed |