US5565060A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and compositions for the selective etching of silicon
Assignee: International Business Machines Corp
•
Filing: 1995-06-06
•
Granted: 1996-10-15
•
Expires: 2015-06-06
Abstract
Abstract Methods and compositions for the selective etching of silicon in the presence of p-doped silicon are disclosed whereby a portion of a silicon surface may be dissolved while a p-doped pattern in the surface remains substantially undissolved. The compositions comprise (a) an aqueous solution of an alkali metal hydroxide or a tetraalkylammonium hydroxide; and (b) a high flash point alcohol, phenol, polymeric alcohol, or polymeric phenol.
Inventors
- 👤 Larry W. Austin
- 👤 Harold G. Linde
- 👤 James S. Nakos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:00
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/126; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/644; Y; Y10; Y10S; Y10S438/00; Y10S438/914; Y10S438/924
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
50 words
A method for the controlled etching of a silicon substrate comprising exposing said silicon substrate to a mixture of (a) an aqueous solution of a base chosen from the group consisting of alkali metal hydroxides and tetraalkylammonium hydroxide and (b) a polymer, the repeating units of which possess hydroxyl functions.
Claim 2
Independent Claim
50 words
A method for the controlled etching of a silicon substrate comprising exposing said silicon substrate to a mixture of (a) an aqueous solution of a base chosen from the group consisting of alkali metal hydroxides and tetraalkylammonium hydroxide and (b) a polymer, the repeating units of which possess hydroxyl functions.
Claim 3
Dependent Claim
13 words
A method according to claim 1 wherein said polymer is a novolac resin.
Claim 4
Dependent Claim
20 words
A method according to claim 2 wherein said novolac has the formula ##STR5## and p is from 20 to 85.
Claim 5
Dependent Claim
16 words
A method according to claim 3 wherein said aqueous solution is from 0.5 to 3.0N KOH.
Claim 6
Dependent Claim
21 words
A method according to claim 4 wherein said novolac is present in an amount from 0.05 ppm to 2% by weight.
Claim 7
Dependent Claim
23 words
A method according to claim 5 further characterized in that said silicon substrate is exposed to said mixture at 45° to 105° C.
Claim 8
Dependent Claim
12 words
A method according to claim 1 wherein said polymer is a poly(hydroxystyrene).
Claim 9
Dependent Claim
21 words
A method according to claim 7 wherein said poly (hydroxystyrene) has the formula ##STR6## and q is from 20 to 200.
Claim 10
Dependent Claim
31 words
A method according to claim 8 wherein said aqueous solution is from 0.5 to 3.0N KOH and said poly(hydroxystyrene) is present in an amount from 0.05 ppm to 2% by weight.
Claim 11
Dependent Claim
12 words
A method according to claim 1 wherein said polymer is poly(vinyl alcohol).
Claim 12
Dependent Claim
42 words
A method according to claim 10 wherein said aqueous solution is from 0.5 to 3.0N KOH, said poly(vinyl alcohol) is of molecular weight from 5,000 to 10,000 and said poly(vinyl alcohol) is present in an amount from 0.01% to 5% by weight.
Claim 13
Independent Claim
93 words
A method for fabricating a three-dimensional p-doped structure on a surface of a silicon wafer comprising: (a) patterning said surface of said wafer with a pattern containing at least 2×10 19 atoms/cm 3 of p-dopant; and (b) exposing said surface to a solution of a polymer and an aqueous base, said polymer having repeating units which possess hydroxyl functions, and said base chosen from the group consisting of alkali metal hydroxides and tetraalkylammonium hydroxides, whereby a portion of said silicon surface of said wafer is dissolved and said p-doped pattern remains substantially undissolved.
Claim 14
Independent Claim
93 words
A method for fabricating a three-dimensional p-doped structure on a surface of a silicon wafer comprising: (a) patterning said surface of said wafer with a pattern containing at least 2×10 19 atoms/cm 3 of p-dopant; and (b) exposing said surface to a solution of a polymer and an aqueous base, said polymer having repeating units which possess hydroxyl functions, and said base chosen from the group consisting of alkali metal hydroxides and tetraalkylammonium hydroxides, whereby a portion of said silicon surface of said wafer is dissolved and said p-doped pattern remains substantially undissolved.
Claim 15
Independent Claim
74 words
A method for etching a surface of a silicon substrate, said surface having implanted or diffused therein a boron-doped pattern with a dopant level above 2×10 19 atoms/cm 3 comprising exposing said surface to a solution of from 0.05 to 300 ppm of novolac resin in from 0.5 to 2.0N aqueous potassium hydroxide at 45° to 105° C. whereby a portion of said silicon substrate is dissolved and said boron-doped pattern remains substantially undissolved.
Claim 16
Independent Claim
74 words
A method for etching a surface of a silicon substrate, said surface having implanted or diffused therein a boron-doped pattern with a dopant level above 2×10 19 atoms/cm 3 comprising exposing said surface to a solution of from 0.05 to 300 ppm of novolac resin in from 0.5 to 2.0N aqueous potassium hydroxide at 45° to 105° C. whereby a portion of said silicon substrate is dissolved and said boron-doped pattern remains substantially undissolved.
References Cited (Backward Citations)
US3160539A
Cited
US3506509A
Cited
US3765969A
Cited
US3738881A
Cited
US3846198A
Cited
US3909325A
Cited
US4339340A
Cited
US4137123A
Cited
US4113551A
Cited
US4567451A
Cited
US4781853A
Cited
US4859280A
Cited
US4918030A
Cited
US4941941A
Cited
US5259888A
Cited
US5431777A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-10-15 | 2000-04-15 | 2000-10-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-10-15 | 2004-04-15 | 2004-10-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-10-15 | 2008-04-15 | 2008-10-15 | $7700.00 | Window Closed / Lapsed |