US5419804A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor etching process
Assignee: Nortel Networks UK Ltd
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Filing: 1994-02-16
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Granted: 1995-05-30
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Expires: 2014-02-16
Abstract
Abstract A process for plasma etching a compound semiconductor heterostructure, e.g. to fabricate a ridge laser on a wavelength demultiplexer comprises anisotropic etching of the semiconductor by exposure to a plasma incorporating methane, hydrogen and oxygen. The oxygen content of the plasma is derived from a gaseous precursor such as carbon dioxide or nitrous oxide.
Inventors
- 👤 Sureshchandra M. Ojha
- 👤 Stephen J. Clements
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 13:42
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/20; H01S5/22; H10; H10P; H10P50/00; H10P50/20; H10P50/24; H10P50/246; H01S5/02; H01S5/026; H01S5/2054; H01S5/2081
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
67 words
A process for the anisotropic dry etching of a compound semiconductor heterostructure, the process including selectively masking a major surface of the heterostructure and exposing the masked heterostructure to a radio-frequency plasma comprising a mixture of methane and hydrogen together with carbon dioxide, nitrous oxide or mixtures thereof whereby to etch anisotropically the unmasked portion of the heterostructure in a direction generally perpendicular to the major surface.
Claim 2
Dependent Claim
67 words
A process for the anisotropic dry etching of a compound semiconductor heterostructure, the process including selectively masking a major surface of the heterostructure and exposing the masked heterostructure to a radio-frequency plasma comprising a mixture of methane and hydrogen together with carbon dioxide, nitrous oxide or mixtures thereof whereby to etch anisotropically the unmasked portion of the heterostructure in a direction generally perpendicular to the major surface.
Claim 3
Dependent Claim
75 words
A process for the anisotropic dry etching of a compound semiconductor heterostructure, the process including selectively masking a major surface of the heterostructure, and exposing the masked heterostructure to a radio frequency plasma comprising 190 to 195 sccm (standard cubic centimetres per minute) hydrogen, 30 to 35 sccm methane and 5 to 8 sccm carbon dioxide whereby to etch anisotropically the unmasked portion of the heterostructure in a direction generally perpendicular to the major surface.
Claim 4
Dependent Claim
75 words
A process for the anisotropic dry etching of a compound semiconductor heterostructure, the process including selectively masking a major surface of the heterostructure, and exposing the masked heterostructure to a radio frequency plasma comprising 190 to 195 sccm (standard cubic centimetres per minute) hydrogen, 30 to 35 sccm methane and 5 to 8 sccm carbon dioxide whereby to etch anisotropically the unmasked portion of the heterostructure in a direction generally perpendicular to the major surface.
Claim 5
Dependent Claim
27 words
A process as claimed in claim 2, wherein said plasma is generated between a first grounded electrode and a second electrode to which radio-frequency power is applied.
Claim 6
Dependent Claim
33 words
A process as claimed in claim 3, wherein a steady (d.c.) electrical bias is maintained between the electrodes, the second electrode being maintained at a negative potential with reference to the first electrode.
Claim 7
Dependent Claim
20 words
A process as claimed in claim 4, wherein said plasma is maintained at a pressure of 1 to 200 mtorr.
Claim 8
Dependent Claim
20 words
A process as claimed in claim 5, wherein the plasma is maintained at a pressure of 50 to 100 mtorr.
Claim 9
Dependent Claim
23 words
A process as claimed in claim 4, wherein the plasma is provided with an energy density of about 1 watt per cubic centimetre.
Claim 10
Dependent Claim
102 words
A process for forming a semiconductor ridge laser, the process including providing a compound semiconductor substrate having an indium gallium arsenide phosphide Q-layer, an indium phosphide layer disposed on said Q-layer and an indium gallium arsenide surface layer, applying a mask to a region of said surface layer corresponding to the position of the laser ridge, and exposing the masked structure under reduced pressure to a radio frequency plasma whereby to remove the unmasked regions of said surface layer and define said ridge, wherein the plasma comprises a mixture of methane and hydrogen together with carbon dioxide, nitrous oxide or mixtures thereof.
Claim 11
Dependent Claim
102 words
A process for forming a semiconductor ridge laser, the process including providing a compound semiconductor substrate having an indium gallium arsenide phosphide Q-layer, an indium phosphide layer disposed on said Q-layer and an indium gallium arsenide surface layer, applying a mask to a region of said surface layer corresponding to the position of the laser ridge, and exposing the masked structure under reduced pressure to a radio frequency plasma whereby to remove the unmasked regions of said surface layer and define said ridge, wherein the plasma comprises a mixture of methane and hydrogen together with carbon dioxide, nitrous oxide or mixtures thereof.
Claim 12
Dependent Claim
15 words
A laser or a wavelength demultiplexer fabricated by a process as claimed in claim 8.
References Cited (Backward Citations)
US5068007A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-05-29 | 1998-11-28 | 1999-05-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-29 | 2002-11-28 | 2003-05-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-29 | 2006-11-28 | 2007-05-30 | $7700.00 | Window Closed / Lapsed |