US4927781A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making a silicon integrated circuit waveguide
Assignee: Individual
•
Filing: 1989-03-20
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Granted: 1990-05-22
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Expires: 2009-03-20
Abstract
Abstract A method for forming a semiconductor waveguide includes forming a layer of expitaxial silicon over a substrate. The impurity concentration of the layer is higher than that of the substrate. A second layer of epitaxial silicon is disposed over the upper surface of the layer with a higher resistivity than that of the substrate. A masking layer is then disposed over the substrate and then patterned, and then the layer selectively etched down to the upper surface of the layer. The layer is then porified to form an insulating layer from the layer. The porous film is then converted by oxidation to a silicon dioxide layer. The sidewalls of the resulting ridge are then oxidized to form sidewall layers and then the masking layer removed from the upper layer. The upper surface of ridge is oxidized to form an upper insulating layer to extend the sidewall layer over the entire upper surface and sidewalls of the ridge. A layer of insulating material is then disposed over the substrate.
Inventors
- 👤 Robert O. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 06:44
CPC Classifications
G; G02; G02B; G02B6/00; G02B6/10; G02B6/12; G02B6/13; G02B6/136; Y; Y10; Y10S; Y10S148/00; Y10S148/095; Y10S148/118; Y10S438/00; Y10S438/911; Y10S438/96
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
221 words
A method for fabricating a semiconductor waveguide, comprising: providing a semiconductor substrate having a low or intrinsic level of dopant impurities; forming a first layer of semiconductor material over one surface of the semiconductor substrate to a predetermined thickness; forming a second layer of semiconductor material over the surface of the first layer of semiconductor material; masking the upper surface of the second layer of semiconductor material with a masking layer; patterning the second layer and masking to define at least one ridge; selectively etching the second layer of semiconductor material and the masking layer in accordance with the pattern to etch the second layer down from the upper surface thereof and substantially to the upper surface of the first layer of semiconductor material to form at least one ridge having an upper surface and two substantially vertical surfaces and a lower surface adjacent the upper surface of the first layer of semiconductor material; converting the first layer of semiconductor material to an insulating material adjacent the lower surface of the at least one ridge; forming a layer of insulating material on the substantially vertical surfaces of the at least one ridge; removing the masking layer from the upper surface of the at least one ridge; and forming an insulating layer on the upper surface of the at least one ridge.
Claim 2
Independent Claim
221 words
A method for fabricating a semiconductor waveguide, comprising: providing a semiconductor substrate having a low or intrinsic level of dopant impurities; forming a first layer of semiconductor material over one surface of the semiconductor substrate to a predetermined thickness; forming a second layer of semiconductor material over the surface of the first layer of semiconductor material; masking the upper surface of the second layer of semiconductor material with a masking layer; patterning the second layer and masking to define at least one ridge; selectively etching the second layer of semiconductor material and the masking layer in accordance with the pattern to etch the second layer down from the upper surface thereof and substantially to the upper surface of the first layer of semiconductor material to form at least one ridge having an upper surface and two substantially vertical surfaces and a lower surface adjacent the upper surface of the first layer of semiconductor material; converting the first layer of semiconductor material to an insulating material adjacent the lower surface of the at least one ridge; forming a layer of insulating material on the substantially vertical surfaces of the at least one ridge; removing the masking layer from the upper surface of the at least one ridge; and forming an insulating layer on the upper surface of the at least one ridge.
Claim 3
Dependent Claim
41 words
The method of claim 1 wherein the first layer of semiconductor material has a higher concentration of dopant impurities than the semiconductor substrate and the second layer of semiconductor material has a lower concentration of dopant impurities than the semiconductor substrate.
Claim 4
Dependent Claim
41 words
The method of claim 1 wherein the step of converting the first layer of semiconductor insulating material comprises: porifying the first layer of semiconductor material; and converting the porified semiconductor material in the first layer to a layer of silicon dioxide.
Claim 5
Dependent Claim
24 words
The method of claim 3 wherein said first layer of semiconductor material comprises an expitaxial layer having a higher conductivity than the semiconductor substrate.
Claim 6
Dependent Claim
40 words
The method of claim 4 wherein the second layer of semiconductor material is comprised of an expitaxial layer of semiconductor material having a concentration lower than that of the semiconductor substrate to provide a high resistivity layer and highly light-transmissive.
Claim 7
Dependent Claim
25 words
The method of claim 3 wherein the semiconductor substrate and the semiconductor material of the first and second layer is comprised of silicon based compounds.
Claim 8
Dependent Claim
39 words
The method of claim 3 wherein the first layer of semiconductor material is comprised of an expitaxial layer of silicon and the step of porifying the first layer results in the formation of silicon dioxide from the first layer.
Claim 9
Dependent Claim
78 words
The method of claim 3 wherein the step of patterning the upper surface of the second layer of semiconductor material comprises: forming a layer of masking material over the upper surface of the second layer of semiconductor material; patterning the masking layer to find the upper surface of the at least one ridge; and wherein the masking layer is utilized to protect the upper surface of the at least one ridge during formation of the insulating sidewall layers.
Claim 10
Dependent Claim
34 words
The method of claim 3 wherein the step of forming the insulating sidewall layers comprises forming the insulating sidewall layers by thermal oxidation of the substantially vertical surfaces of the at least one ridge.
Claim 11
Dependent Claim
50 words
The method of claim 3 wherein the step of forming the insulating layer on the upper surface comprises: oxidizing the upper surface of the at least one ridge to form a thin layer of thermal oxidation; and forming a conformal layer of silicon dioxide over the surface of the substrate.
Claim 12
Dependent Claim
43 words
The method of claim 1 wherein the step of selectively etching the second layer of semiconductor material comprises etching through the masking layer and the second layer of semiconductor material and partially into the upper surface of the first layer of semiconductor material.
References Cited (Backward Citations)
US4104090A
Cited
JPS5420678A
Cited
JPS57149749A
Cited
JPS5877240A
Cited
US4464762A
Cited
JPS58192344A
Cited
US4426440A
Cited
US4750799A
Cited
US4737946A
Cited
US4628591A
Cited
JPS62124511A
Cited
US4810667A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-21 | 1993-11-20 | 1994-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-21 | 1997-11-20 | 1998-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-21 | 2001-11-20 | 2002-05-22 | $7700.00 | Window Closed / Lapsed |