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US4294651A
Expired / Lapsed
US
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Method of surface-treating semiconductor substrate
Assignee: Fujitsu Ltd
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Filing: 1980-05-16
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Granted: 1981-10-13
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Expires: 2000-05-16
Abstract
Abstract A surface or surfaces of a semiconductor substrate are roughened by etching the substrate with an etchant containing (i) hydrofluoric acid, ammonium fluoride and/or acid ammonium fluoride, (ii) at least one manganese- or chromium-containing oxidizing agent, such as potassium permanganate, potassium manganate, chromium trioxide, potassium or sodium chromate and potassium or sodium dichromate, and (iii) an alkali. If a rougher surface or surfaces are desired, the substrate is pre-etched with an etchant containing (i) the fluorine-containing compound and (ii) the manganese-containing oxidizing agent, and then, etched with the above-mentioned etchant.
Inventors
- 👤 Sohshi Ohmura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 14:17
CPC Classifications
H; H10; H10P; H10P70/00; H10P70/10; H10P70/15; H10P50/00; H10P50/60; H10P50/64; H10P50/642
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
79 words
A method of roughening at least one surface of a silicon semiconductor substrate comprising the step of bringing each surface of the semiconductor substrate that is to be roughened into contact with an etchant comprising (i) at least one fluorine-containing compound selected from the group consisting of hydrofluoric acid (HF), ammonium fluoride (NH 4 F) and acid ammonium fluoride (NH 4 HF 2 ), (ii) at least one oxidizing agent selectively containing manganese and chromium, and (iii) an alkali.
Claim 2
Independent Claim
79 words
A method of roughening at least one surface of a silicon semiconductor substrate comprising the step of bringing each surface of the semiconductor substrate that is to be roughened into contact with an etchant comprising (i) at least one fluorine-containing compound selected from the group consisting of hydrofluoric acid (HF), ammonium fluoride (NH 4 F) and acid ammonium fluoride (NH 4 HF 2 ), (ii) at least one oxidizing agent selectively containing manganese and chromium, and (iii) an alkali.
Claim 3
Dependent Claim
49 words
The method of claim 1, wherein the etchant contains, based on the weight of the etchant, (i) 7% to 38% by weight of the fluorine-containing compound, (ii) 2.5% to 7% by weight of the manganese- or chromium-containing oxidizing agent and (iii) 1% to 10% by weight of the alkali.
Claim 4
Dependent Claim
37 words
The method of claim 1, wherein the etchant comprises, based on the weight of the etchant, (i) 13% to 35% by weight of the fluorine-containing compound and (ii) 3% to 7% by weight of the oxidizing agent.
Claim 5
Dependent Claim
32 words
The method of claim 1, 2 or 3, wherein the oxidizing agent is selected from the group consisting of potassium permanganate (KMnO 4 ) and potassium manganate (K 2 MnO 4 ).
Claim 6
Dependent Claim
57 words
The method of claim 1, 2 or 3, wherein the oxidizing agent is selected from the group consisting of chromium trioxide (CrO 3 ), potassium chromate (K 2 CrO 4 ), potassium dichromate (K 2 Cr 2 O 7 ), sodium chromate (Na 2 CrO 4 ) and sodium dichromate (Na 2 Cr 2 O 7 ).
Claim 7
Dependent Claim
17 words
The method of claim 1, 2 or 3, wherein the alkali is potassium hydroxide or sodium hydroxide.
Claim 8
Dependent Claim
99 words
A method according to claim 1, 2 or 3, wherein prior to the step of bringing each surface of the semiconductor substrate to be etched into contact with the etchant, each said surface is subjected to a pre-etching by using an etchant comprising (i) at least one fluorine-containing compound selected from the group consisting of hydrofluoric acid (HF), ammonium fluoride (NH 4 F) and acid ammonium fluoride (NH 4 HF 2 ) and (ii) at least one manganese-containing oxidizing agent selected from the group consisting of potassium permanganate (KMnO 4 ) and potassium manganate (K 2 MnO 4 ).
Claim 9
Dependent Claim
44 words
The method of claim 7, wherein the etchant used for the pre-etching comprises, based on the weight of the etchant, (i) approximately 15% to 30% by weight of the fluorine-containing compound and (ii) approximately 5% to 7% by weight of the manganese-containing oxidizing agent.
Claim 10
Dependent Claim
37 words
The method of claim 1 or 2, said semiconductor substrate comprising a wafer of at least 75 mm diameter, and said etching comprising etching one surface of said wafer down to a maximum thickness of 200 microns.
Claim 11
Dependent Claim
33 words
The method of claim 7, said substrate comprising a wafer of at least 75 mm diameter, and said etching comprising one surface of said wafer down to a maximum thickness of 150 microns.
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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) | 1984-10-12 | 1985-04-13 | 1985-10-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-12 | 1989-04-13 | 1989-10-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-12 | 1993-04-13 | 1993-10-13 | $7700.00 | Window Closed / Lapsed |