US4285762A
Expired / Lapsed
US
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Plasma etching of amorphous silicon (SE-35)
Assignee: ExxonMobil Technology and Engineering Co
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Filing: 1979-12-31
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Granted: 1981-08-25
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Expires: 1999-12-31
Abstract
Abstract Amorphous silicon is selectively etched by concurrently exposing the silicon to a ionized plasma containing hydrogen and heating the silicon to a temperature of between about 150° C. to about 350° C. In one embodiment the selective etching technique is utilized to texture the surface of the amorphous silicon reducing the reflectivity thereof to less then about 5%.
Inventors
- 👤 Theodore D. Moustakas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:43
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/268; H10F; H10F77/00; H10F77/70; H10F77/703; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y10; Y10S; Y10S438/00; Y10S438/964
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
51 words
A method for selectively etching amorphous silicon comprising: (a) depositing a layer of amorphous silicon into a substrate; (b) heating said layer to a temperature between about 150° C. and about 350° C. and concurrently exposing said silicon layer to an ionized plasma containing hydrogen wherein the exposed silicon is etched.
Claim 2
Independent Claim
51 words
A method for selectively etching amorphous silicon comprising: (a) depositing a layer of amorphous silicon into a substrate; (b) heating said layer to a temperature between about 150° C. and about 350° C. and concurrently exposing said silicon layer to an ionized plasma containing hydrogen wherein the exposed silicon is etched.
Claim 3
Dependent Claim
27 words
The method of claim 1 wherein said hydrogen containing plasma is further characterized as electral ionizing energy capacitively coupled to a gaseous mixture of hydrogen and argon.
Claim 4
Dependent Claim
24 words
The method of claim 2 wherein said gaseous mixture comprises a partial pressure of hydrogen ranging from about 75 millitorr to about 100 millitorr.
Claim 5
Dependent Claim
15 words
The method of claim 3 wherein said partial pressure of hydrogen is about 90 millitorr.
Claim 6
Dependent Claim
25 words
The method of claim 3 or 4 wherein said silicon film is maintained at a temperature of between about 200° C. and about 275° C.
Claim 7
Dependent Claim
24 words
The method of claim 6 wherein said ionizing energy comprises between about 1 watt/cm 2 and about 2 watts/cm 2 of alternating current voltage.
Claim 8
Dependent Claim
31 words
The method of claim 6 wherein a positive voltage bias of between about 50 volts and about 100 volts is applied to said substrate during the etching of the silicon layer.
Claim 9
Dependent Claim
48 words
The method of claim 1 wherein a surface of said silicon is etched to provide a textured surface which is characterized as having cavities in said surface having an average inter-cavity spacing less than about one micron and an average cavity depth of greater than about 6000 A.
Claim 10
Dependent Claim
19 words
The method of claim 9 wherein said average inter-cavity spacing is between about 1000 A and about 3000 A.
Claim 11
Independent Claim
104 words
A method for reducing the reflectivity of amorphous silicon comprising etching a surface region of a layer of amorphous silicon in an ionized plasma containing a partial pressure of about 90 mTorr of hydrogen wherein said surface region is etched to form cavities, said cavities having an average inter-cavity spacing between about 1000 A and about 3000 A and wherein light energy having a wavelength ranging from 0.4 microns to about 0.8 microns incident upon said textured surface experiences a graded transition from a first transparent medium to a second absorbing medium, substantially reducing the reflectivity of said light energy from the silicon surface.
Claim 12
Independent Claim
104 words
A method for reducing the reflectivity of amorphous silicon comprising etching a surface region of a layer of amorphous silicon in an ionized plasma containing a partial pressure of about 90 mTorr of hydrogen wherein said surface region is etched to form cavities, said cavities having an average inter-cavity spacing between about 1000 A and about 3000 A and wherein light energy having a wavelength ranging from 0.4 microns to about 0.8 microns incident upon said textured surface experiences a graded transition from a first transparent medium to a second absorbing medium, substantially reducing the reflectivity of said light energy from the silicon surface.
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) | 1984-08-24 | 1985-02-23 | 1985-08-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-08-24 | 1989-02-23 | 1989-08-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-08-24 | 1993-02-23 | 1993-08-25 | $7700.00 | Window Closed / Lapsed |