US4824800A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating semiconductor devices
Assignee: Mitsubishi Electric Corp
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Filing: 1988-04-28
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Granted: 1989-04-25
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Expires: 2008-04-28
Abstract
Abstract An improved method of lift-off processing semiconductor devices including ohmic electrodes, gate electrodes, metal wiring, and the like. The invention provides for the production of an access groove pattern in the surface of the substrate prior to the application of the resist by photolithography and the deposition of metallization. The access groove pattern increases the opportunity for the chemical stripper to dissolve the resist and lift away the unrequired portions of the metallization, thus improving the reliability of the lift-off.
Inventors
- 👤 Hirozo Takano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:39
CPC Classifications
H; H10; H10D; H10D30/00; H10D30/01; H10D30/061; H10D30/0612; H10D64/00; H10D64/01; H10D64/011; H10P; H10P76/00; H10P76/20; H10P76/202; Y; Y10; Y10S; Y10S148/00; Y10S148/10
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
142 words
A method of fabricating a semiconductor device on a substrate which includes formation of electrodes by selective plating using a liftoff procedure, the method comprising the steps of: forming a pattern of access grooves in the substrate associated with the semiconductor device in such a way as to assist in the lift-off of photoresist, producing a photoresist pattern on a partly fabricated semiconductor device having open areas for defining electrode positions and photoresist covered areas protecting the remaining surface of the semiconductor device, plating electrode material over the semiconductor device, and applying solvent to the plated semiconductor device to invade the photoresist at the exposed edges and lift off the photoresist and the overlying plating, the access grooves being of a depth sufficient to provide exposed edges to allow access by the solvent to the photoresist underlying the plating to assure lift-off.
Claim 2
Independent Claim
142 words
A method of fabricating a semiconductor device on a substrate which includes formation of electrodes by selective plating using a liftoff procedure, the method comprising the steps of: forming a pattern of access grooves in the substrate associated with the semiconductor device in such a way as to assist in the lift-off of photoresist, producing a photoresist pattern on a partly fabricated semiconductor device having open areas for defining electrode positions and photoresist covered areas protecting the remaining surface of the semiconductor device, plating electrode material over the semiconductor device, and applying solvent to the plated semiconductor device to invade the photoresist at the exposed edges and lift off the photoresist and the overlying plating, the access grooves being of a depth sufficient to provide exposed edges to allow access by the solvent to the photoresist underlying the plating to assure lift-off.
Claim 3
Dependent Claim
50 words
A method of producing a semiconductor device as claimed in claim 1, wherein the depth of the access grooves is in the range of about 1 micron to about 5 microns, and the width of the access grooves is in the range of about 2 microns to about 5 microns.
Claim 4
Dependent Claim
30 words
A method of producing a semiconductor device as claimed in claim 1, wherein the semiconductor device is a field effect transistor, said access groove pattern framing the field effect transistor.
Claim 5
Dependent Claim
32 words
A method of producing a semiconductor device as claimed in claim 1, wherein the semiconductor device is a monolithic microwave integrated circuit, said access groove pattern framing the monolithic microwave integrated circuit.
Claim 6
Dependent Claim
28 words
A method of producing a semiconductor device as claimed in claim 4, wherein the access groove pattern is discontinuous around the periphery of the monolithic microwave integrated circuit.
Claim 7
Dependent Claim
29 words
A method of producing a semiconductor device as claimed in claim 4, wherein the access groove pattern is substantially continuous around the periphery of the monolithic microwave integrated circuit.
Claim 8
Dependent Claim
46 words
A method of producing a semiconductor device as claimed in claim 1, wherein the semiconductor device is a monolithic microwave integrated circuit, said access groove pattern framing (a) the monolithic microwave integrated circuit, and (b) at least one active device within the monolithic microwave integrated circuit.
Claim 9
Dependent Claim
45 words
A method of producing a semiconductor device as claimed in claim 1, wherein the substrate is a wafer for plural semiconductor devices, said wafer having scribe lines on the surface for separating individual semiconductor devices, and said access grooves being positioned near the scribe lines.
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) | 1992-04-24 | 1992-10-24 | 1993-04-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-04-24 | 1996-10-24 | 1997-04-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-04-24 | 2000-10-24 | 2001-04-25 | $7700.00 | Window Closed / Lapsed |