Patent US4243435A successfully refreshed from Google Patents.
US4243435A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bipolar transistor fabrication process with an ion implanted emitter
Assignee: International Business Machines Corp
•
Filing: 1979-06-22
•
Granted: 1981-01-06
•
Expires: 1999-06-22
Abstract
Abstract A very high current ion implanted emitter is formed in a diffused base. Windows are made through the silicon nitride and silicon dioxide layes to both the base contact and the emitter regions using a resist mask. These regions are then protected by resist and the collector contact window is opened through the remainder of the silicon dioxide layer to the reach through region. A screen oxide is then grown in all the exposed areas after the removal of the resist mask. A resist mask is applied which covers only the base and Schottky anode regions. Arsenic is then implanted through the exposed screened areas followed by an etch back step to remove the top damaged layer. With some remaining screen oxide serving as a cap, the emitter drive-in is done.
Inventors
- 👤 Conrad A. Barile
- 👤 Goerge R. Goth
- 👤 James S. Makris
- 👤 Arunachala Nagarajan
- 👤 Raj K. Raheja
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:13
CPC Classifications
H; H10; H10D; H10D84/00; H10D84/60; H10D84/611; H10D84/613; H10D84/617; H10P; H10P76/00; H10P76/40; Y; Y10; Y10S; Y10S148/00; Y10S148/139
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
132 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector contact window partially through said mask while protecting the remainder of said mask with a resist layer, said mask being thicker in the region of the collector contact than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base window and leaves said emitter window exposed, and; introducing impurities through said emitter window by ion implantation.
Claim 2
Independent Claim
132 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector contact window partially through said mask while protecting the remainder of said mask with a resist layer, said mask being thicker in the region of the collector contact than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base window and leaves said emitter window exposed, and; introducing impurities through said emitter window by ion implantation.
Claim 3
Dependent Claim
39 words
The method of claim 1 wherein said mask is a composite layer of silicon dioxide under silicon nitride and the silicon dioxide is thicker in the region of the collector contact than in the region of the emitter window.
Claim 4
Dependent Claim
13 words
The method of claim 1 wherein said thin protective layer is silicon dioxide.
Claim 5
Dependent Claim
10 words
The method of claim 1 wherein said impurity is arsenic.
Claim 6
Dependent Claim
44 words
The method of claim 1 wherein the ion implantation is a high energy 40 to 60 kv high dose rate 1.8 to 2.2 ma current implantation for a time to provide a dosage of from about 8.5×10 15 to 10×10 15 atoms/cm 2 .
Claim 7
Dependent Claim
29 words
The process of claim 1 including the steps of removing the top portion of the protective layer following ion implantation and then heating the substrate to drive-in the impurity.
Claim 8
Dependent Claim
63 words
The method of claim 2 wherein the emitter and base contact window are formed by etching through the silicon nitride by reactive ion etching and through the silicon dioxide by wet etching and the collector contact window is partially formed at the same time by etching through the silicon nitride by reactive ion etching and partially through the silicon dioxide by wet etching.
Claim 9
Dependent Claim
27 words
The method of claim 5 wherein the energy is about 50 kv, the current about 2 ma, and the dosage about 9.5×10 15 arsenic atoms/cm 2 .
Claim 10
Dependent Claim
16 words
The process of claim 6 including the steps of removing the remaining protective layer after drive-in.
Claim 11
Dependent Claim
29 words
The method of claim 3 wherein said thin protective layer has a thickness of about 200 to 1,000 A with tolerances of ±10% around the nominal of 250 A.
Claim 12
Dependent Claim
25 words
The method of claim 7 wherein the reactive ion etching is in a CF 4 containing atmosphere and the wet etch contains aqueous hydrofluoric acid.
Claim 13
Dependent Claim
23 words
The method of claim 7 where the remainder of the collector contact window is formed by a wet etch containing aqueous hydrofluoric acid.
Claim 14
Dependent Claim
16 words
The method of claim 10 wherein said protective layer has a thickness of about 250 A.
Claim 15
Independent Claim
174 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector and Schottky barrier diode anode and cathode contact windows partially through said mask while protecting the remainder of said mask with a resist layer, said mask being thicker in the region of the collector and Schottky barrier anode and cathode contact windows than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window and the Schottky barrier diode anode and cathode contact windows through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base and Schottky barrier diode anode windows and leaves said emitter and Schottky barrier diode cathode windows exposed, and; introducing impurities through said emitter window and said Schottky barrier diode cathode contact window by ion implantation.
Claim 16
Independent Claim
174 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector and Schottky barrier diode anode and cathode contact windows partially through said mask while protecting the remainder of said mask with a resist layer, said mask being thicker in the region of the collector and Schottky barrier anode and cathode contact windows than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window and the Schottky barrier diode anode and cathode contact windows through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base and Schottky barrier diode anode windows and leaves said emitter and Schottky barrier diode cathode windows exposed, and; introducing impurities through said emitter window and said Schottky barrier diode cathode contact window by ion implantation.
Claim 17
Independent Claim
187 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector and Schottky barrier diode anode and cathode contact windows partially through said mask while protecting the remainder of said mask with a resist layer, said mask comprising a composite layer of silicon dioxide under silicon nitride, the silicon dioxide being thicker in the region of the collector and Schottky barrier anode and cathode contact windows than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window and the Schottky barrier diode anode and cathode contact windows through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base and Schottky barrier diode anode windows and leaves said emitter and Schottky barrier diode cathode windows exposed, and; introducing impurities through said emitter window and said Schottky barrier diode cathode contact window by ion implantation.
Claim 18
Independent Claim
187 words
A method of forming semiconductor devices in a semiconductor substrate comprising; forming emitter and base contact windows through a mask on said substrate and a collector and Schottky barrier diode anode and cathode contact windows partially through said mask while protecting the remainder of said mask with a resist layer, said mask comprising a composite layer of silicon dioxide under silicon nitride, the silicon dioxide being thicker in the region of the collector and Schottky barrier anode and cathode contact windows than in the region of the emitter window; removing said resist layer, forming the remainder of the collector contact window and the Schottky barrier diode anode and cathode contact windows through said mask while protecting said emitter and base contact windows with a second resist layer; removing said second resist layer; forming a thin protective layer over at least said emitter window; forming a third resist layer which covers said base and Schottky barrier diode anode windows and leaves said emitter and Schottky barrier diode cathode windows exposed, and; introducing impurities through said emitter window and said Schottky barrier diode cathode contact window by ion implantation.
Claim 19
Dependent Claim
68 words
The method of claim 15 wherein the emitter and base contact window are formed by etching through the silicon nitride by reactive ion etching and through the silicon dioxide by wet etching and the collector Schottky barrier anode and cathode contact windows are partially formed at the same time by etching through the silicon nitride by reactive ion etching and partially through the silicon dioxide by wet etching.
Claim 20
Dependent Claim
25 words
The method of claim 16 wherein the reactive ion etching is in a CF 4 containing atmosphere and the wet etch contains aqueous hydrofluoric acid.
Claim 21
Dependent Claim
30 words
The method of claim 16 where the remainder of the collector and Schottky barrier diode anode and cathode contact windows are formed by a wet etch containing aqueous hydrofluoric acid.
Claim 22
Dependent Claim
13 words
The method of claim 15 wherein said thin protective layer is silicon dioxide.
Claim 23
Dependent Claim
19 words
The method of claim 19 wherein said thin protective layer has a thickness of about 200 to 1,000 A.
Claim 24
Dependent Claim
16 words
The method of claim 20 wherein said protective layer has a thickness of about 250 A.
Claim 25
Dependent Claim
10 words
The method of claim 15 wherein said impurity is arsenic.
Claim 26
Dependent Claim
44 words
The method of claim 14 wherein the ion implantation is a high energy 40 to 60 kv high dose rate 1.8 to 2.2 ma current implantation for a time to provide a dosage of from about 8.5×10 15 to 10×10 15 atoms/cm 2 .
Claim 27
Dependent Claim
26 words
The method of claim 23 wherein the energy is about 50 kv, the current about 2 ma, the dosage about 9.5×10 15 arsenic atoms/cm 2 .
Claim 28
Dependent Claim
29 words
The process of claim 15 including the steps of removing the top portion of the protective layer following ion implantation and then heating the substrate to drive-in the impurity.
Claim 29
Dependent Claim
16 words
The process of claim 25 including the steps of removing the remaining protective layer after drive-in.
References Cited (Backward Citations)
US3604986A
Cited
US3837936A
Cited
US3928081A
Cited
US3928082A
Cited
US3945856A
Cited
US4018627A
Cited
US4106954A
Cited
US4046606A
Cited
US4131497A
Cited
US4135954A
Cited
US4118250A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-06 | 1984-07-07 | 1985-01-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-06 | 1988-07-07 | 1989-01-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-06 | 1992-07-07 | 1993-01-06 | $7700.00 | Window Closed / Lapsed |