US3929529A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for gettering contaminants in monocrystalline silicon
Assignee: International Business Machines Corp
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Filing: 1974-12-09
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Granted: 1975-12-30
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Expires: 1994-12-09
Abstract
Abstract A method for removing fast diffusing metal contaminants from a monocrystalline silicon body by (1) anodizing at least one side of the body in an aqueous liquid bath under conditions that result in the formation of a porous silicon surface layer, (2) annealing the resultant structure in a non-oxidizing environment, and (3) exposing the body to an oxidizing environment to oxidize the porous silicon layer to SiO2, or alternatively forming a capping layer over the porous silicon layer.
Inventors
- 👤 Michael R Poponiak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 22:00
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/124; H10P14/00; H10P14/60; H10P14/63; H10P14/6302; H10P14/6304; H10P14/6306; H10P14/6308; H10P14/6309; H10P14/6322; H10P14/65; H10P14/6502; H10P14/6508; H10P36/00; H10P36/03; H10P90/15; Y; Y10; Y10S; Y10S148/00; Y10S148/015; Y10S148/024; Y10S148/037; Y10S148/06; Y10S148/085; Y10S148/117; Y10S148/118; Y10S148/122; Y10S438/00; Y10S438/914; Y10S438/923; Y10S438/96; Y10S438/969
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
88 words
A METHOD FOR REMOVING FAST DIFFUSING METL CONTAMINATES FROM A MONOCRYSTALLINE SILICON BODY COMPRISING: ANODIZING AT LEAST ONE SIDE OF SAID BODY IN AN AQUEOUS LIQUID BATH UNDER CONDITIONS THAT RESULT IN THE FORMATION OF A LAYER OF POROUS SILICON, ANNEALING THE RESULTANT STRUCTURE IN A NONOXIDIZING ENVIRONMENT AT A TEMPERATURE AND A LENGTH OF TIME SUFFICIENT TO DIFFUSE THE CONTAMINATES OF INTEREST A DISTANCE AT LEAST THE THICKNESS OF THE BODY, AND EXPOSING THE BODY TO AN OXIDIZING ENVIRONMENT TO OXIDIZE SAID POROUS SILICON LAYER TO SIO2.
Claim 2
Independent Claim
88 words
A METHOD FOR REMOVING FAST DIFFUSING METL CONTAMINATES FROM A MONOCRYSTALLINE SILICON BODY COMPRISING: ANODIZING AT LEAST ONE SIDE OF SAID BODY IN AN AQUEOUS LIQUID BATH UNDER CONDITIONS THAT RESULT IN THE FORMATION OF A LAYER OF POROUS SILICON, ANNEALING THE RESULTANT STRUCTURE IN A NONOXIDIZING ENVIRONMENT AT A TEMPERATURE AND A LENGTH OF TIME SUFFICIENT TO DIFFUSE THE CONTAMINATES OF INTEREST A DISTANCE AT LEAST THE THICKNESS OF THE BODY, AND EXPOSING THE BODY TO AN OXIDIZING ENVIRONMENT TO OXIDIZE SAID POROUS SILICON LAYER TO SIO2.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein said layer of SiO2 is removed by etching.
Claim 4
Dependent Claim
18 words
The method of claim 2 wherein the etching solution used to remove the SiO2 includes a chelating agent.
Claim 5
Dependent Claim
23 words
The method of claim 2 which further includes the step of diffusing an impurity into and through said porous silicon layer before annealing.
Claim 6
Dependent Claim
29 words
The method of claim 4 wherein said impurity is diffused into said body at a concentration that equals or exceeds the solid solubility limit of the impurity in silicon.
Claim 7
Dependent Claim
10 words
The method of claim 5 wherein said impurity is boron.
Claim 8
Dependent Claim
10 words
The method of claim 5 wherein said impurity is phosphorus.
Claim 9
Dependent Claim
11 words
The method of claim 1 wherein the non-oxidizing environment is argon.
Claim 10
Dependent Claim
17 words
The method of claim 1 wherein said annealing is performed at a temperature of at least 1000*C.
Claim 11
Dependent Claim
15 words
The method of claim 1 wherein P type diffused regions are formed in said body.
Claim 12
Dependent Claim
22 words
The method of claim 10 wherein an epitaxial layer is deposited on the top surface of said body over the monocrystalline areas.
Claim 13
Dependent Claim
19 words
The method of claim 1 wherein said oxidizing environment is a steam ambient at a temperature greater than 900*C.
References Cited (Backward Citations)
US2462218A
Cited
US2739882A
Cited
US2948642A
Cited
US3529347A
Cited
US3634204A
Cited
US3579815A
Cited
US3640806A
Cited
US3775262A
Cited
US3874936A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-29 | 1979-06-30 | 1979-12-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-29 | 1983-06-30 | 1983-12-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-29 | 1987-06-30 | 1987-12-30 | $7700.00 | Window Closed / Lapsed |