US4050979A
Expired / Lapsed
US
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Process for thinning silicon with special application to producing silicon on insulator
Assignee: Texas Instruments Inc
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Filing: 1976-01-14
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Granted: 1977-09-27
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Expires: 1996-01-14
Abstract
Abstract This disclosure relates to methods of producing thin layers of silicon as well as thin layers of silicon on insulating substrates such as silicon dioxide or polycrystalline silicon by forming either an n- layer of single crystal silicon over a p++ layer of single crystal silicon or a p- layer of single crystal silicon over an n++ layer of single crystal silicon and then removing either the n++ or p++ single crystal substrate, as the case may be, by utilizing an etch which will only etch the n++ or p++ region and will stop when the n- or p- region, as the case may be, has been reached.
Inventors
- 👤 Ronald K. Smeltzer
- 👤 Kenneth E. Bean
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 10:47
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/644; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/019; H10W10/10; Y; Y10; Y10S; Y10S148/00; Y10S148/051; Y10S148/085; Y10S148/15; Y10S438/00; Y10S438/977
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
154 words
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 1.5 × 10 19 atoms/cc, and b. forming a first oxide layer on said second layer, c. forming a layer of polycrystalline silicon on said first oxide layer, d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts NHO 3 and from about 8 to about 12 parts CH 3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer, and e. forming semiconductor devices in the exposed surface of said second layer.
Claim 2
Independent Claim
154 words
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 1.5 × 10 19 atoms/cc, and b. forming a first oxide layer on said second layer, c. forming a layer of polycrystalline silicon on said first oxide layer, d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts NHO 3 and from about 8 to about 12 parts CH 3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer, and e. forming semiconductor devices in the exposed surface of said second layer.
Claim 3
Dependent Claim
22 words
A method as set forth in claim 1, wherein said first layer is N type and said second layer is P type.
Claim 4
Dependent Claim
33 words
A method as set forth in claim 1, wherein said first layer has a resistivity of about 0.4 ohm-centimeters and said second layer has a resistivity of about 0.005 to about 0.007 ohm-centimeters.
Claim 5
Dependent Claim
33 words
A method as set forth in claim 2, wherein said first layer has a resistivity of about 0.4 ohm-centimeters and said second layer has a resistivity of about 0.005 to about 0.007 ohm-centimeters.
Claim 6
Dependent Claim
53 words
A method as in claim 1, wherein said formation of semiconductor devices is followed by the steps of: forming an insulation layer covering said devices; selectively etching crystallographically oriented grooves extending through said second layer to provide electrical isolation betwen adjacent semiconductor devices; and then forming an additional insulation layer in said grooves.
Claim 7
Independent Claim
141 words
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 7 × 10 18 atoms/cc, and b. forming a first oxide layer over said second layer, c. forming a layer of polycrystalline silicon over said first oxide layer, d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts HNO 3 and from about 8 to about 12 parts CH 3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer.
Claim 8
Independent Claim
141 words
A method of forming thin layers of silicon on an insulating substrate which comprises the steps of a. providing a silicon member having a first layer of one conductivity type and a second layer of opposite conductivity type and having a resistivity of at least an order of magnitude greater than said first layer and a concentration of less than about 7 × 10 18 atoms/cc, and b. forming a first oxide layer over said second layer, c. forming a layer of polycrystalline silicon over said first oxide layer, d. etching said first layer with an etching solution consisting of, by weight, 1 part HF, 3 parts HNO 3 and from about 8 to about 12 parts CH 3 COOH to provide etching away of said first layer, said etching automatically stopping at the junction of said first and second layer.
Claim 9
Dependent Claim
22 words
A method as set forth in claim 6, wherein said first layer is P type and said second layer is N type.
Claim 10
Dependent Claim
33 words
A method as set forth in claim 6, wherein said first layer has a resistivity of about 0.4 ohm-centimeters and said second layer has a resistivity of about 0.005 to about 0.007 ohm-centimeters.
Claim 11
Dependent Claim
33 words
A method as set forth in claim 7, wherein said first layer has a resistivity of about 0.4 ohm-centimeters and said second layer has a resistivity of about 0.005 to about 0.007 ohm-centimeters.
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) | 1980-09-26 | 1981-03-28 | 1981-09-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-09-26 | 1985-03-28 | 1985-09-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-09-26 | 1989-03-28 | 1989-09-27 | $7700.00 | Window Closed / Lapsed |