US3751314A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicon semiconductor device processing
Assignee: AT&T Inc
•
Filing: 1971-07-01
•
Granted: 1973-08-07
•
Expires: 1991-07-01
Abstract
Abstract Silicon semiconductor devices containing boron doped regions are produced using borosilicate glass as a doping source and silica glass as a masking layer. After the device is heated to produce boron diffusion into the silicon surface, a preferential etchant is used to remove the borosilicate glass while leaving the masking layer substantially in place for use in subsequent processing steps. The etchant is an aqueous solution of HF and HNO3.
Inventors
- 👤 L Rankel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 18:26
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/69; H10P14/692; H10P14/6921; H10P14/6922; H10P14/6923; H10P14/63; H10P14/6326; H10P14/6328; H10P14/6334; H10P32/00; H10P32/10; H10P32/14; H10P32/1408; H10P32/141; H10P32/17; H10P32/171; Y; Y10; Y10S; Y10S148/00; Y10S148/043; Y10S148/051; Y10S148/106
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
22 words
A method of claim 1 in which the total molar concentration of the first constituent is between 0.3 molar and 3 molar.
Claim 2
Dependent Claim
24 words
producing a borosilicate glass layer containing between 0.2 weight percent and 15 weight percent boron over at least part of the second portion; and
Claim 3
Dependent Claim
24 words
A method of claim 2 in which the sum of the molar concentration of the first and second constituents is at most nine molar.
Claim 4
Dependent Claim
156 words
a glass removal step; characterized in that the glass removal step consists essentially of contacting the borosilicate glass layer and at least part of the first portion with an etchant for a time at least sufficiently long To remove the borosilicate glass layer which etchant consists essentially of an aqueous solution of a first constituent and a second constituent wherein the first constituent is HF wherein the molar concentration of the first constituent is between 0.1 molar and 4 molar and the second constituent is HNO3 wherein the molar concentration of the second constituent is between 4 molar and 8 molar and is at least two times the molar concentration of the first constituent which etchant removes the borosilicate glass layer at a rate more than three times the rate at which the etchant removes the silica glass masking layer whereby the borosilicate glass layer is removed while leaving the silica glass masking layer substantially intact.
Claim 5
Dependent Claim
39 words
A method of claim 1 in which the borosilicate glass is maintained at a temperature above 800* C for a time greater than 10 minutes allowing diffusion of boron into the n-type silicon substrate thereby producing a p-n junction.
Claim 6
Dependent Claim
39 words
A method of claim 1 in which the silica glass masking layer is produced by covering the first portion and the second portion of the substrate with silica glass and subsequently removing the silica glass from the second portion.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |