Patent US3874959A successfully refreshed from Google Patents.
US3874959A
Expired / Lapsed
US
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Method to establish the endpoint during the delineation of oxides on semiconductor surfaces and apparatus therefor
Assignee: International Business Machines Corp
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Filing: 1973-09-21
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Granted: 1975-04-01
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Expires: 1993-09-21
Abstract
Abstract A semiconductor device having a dielectric coating on at least one surface is mounted in a special holder which will allow the etching solution to contact only one oxide coated surface of the semiconductor to etch the same according to a predetermined pattern. A first electrical lead is connected either directly or indirectly to the opposite surface of the semiconductor and a second electrical lead is connected to an electrode disposed in the etching solution. Both of these are connected to a meter or detector for sensing any current between the two leads through the semiconductor. A chopped d.c. light source is focused to provide a spot of light at at least one etching point so that upon removal of the dielectric, the pulsating light beam will generate an a.c. signal on the semiconductor which will be detected by the meter to signal the etching endpoint.
Inventors
- 👤 Jan P Hoekstra
- 👤 Frederick H Dill
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 12:27
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/282; H10P50/283
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
126 words
APPARATUS FOR DETERMINING THE ETCH ENDPOINT OF AN OXIDE FROM A SEMICONDUCTOR SUBSTRATE COMPRISING: CONTAINER MEANS FOR HOLDING AN ETCHING SOLUTION, SUBSTRATE HOLDING AN ETCHING SOLUTION, SUBSTRATE IN AN ETCHING SOLUTION WITH ONLY ONE OXIDE COATED SURFACE OF SAID SUBSTRATE BEING EXPOSED TO SAID ETCHING SOLUTION, ELECTRICAL DETECTING MEANS DISPOSED IN OPERATIVE RELATION TO OPPOSITE SIDES OF SAID SUBSTRATE FOR DETECTING A SIGNAL GENERATED BY LIGHT IMPINGING ON A SURFACE OF SAID SUBSTRATE, AND LIGHT SOURCE MEANS FOR DIRECTING A BEAM OF LIGHT ON A PORTION OF THE EXPOSED OXIDE COATING TO BE ETCHED AWAY WHEREBY WHEN THE PROPER AMOUNT OF OXIDE HAS BEEN ETCHED AWAY, THE LIGHT BEAM WILL IMPINGE ON THE EXPOSED SURFACE OF SAID SEMICONDUCTOR TO PRODUCE A SIGNAL INDICATING THE ETCH ENDPOINT.
Claim 2
Dependent Claim
126 words
APPARATUS FOR DETERMINING THE ETCH ENDPOINT OF AN OXIDE FROM A SEMICONDUCTOR SUBSTRATE COMPRISING: CONTAINER MEANS FOR HOLDING AN ETCHING SOLUTION, SUBSTRATE HOLDING AN ETCHING SOLUTION, SUBSTRATE IN AN ETCHING SOLUTION WITH ONLY ONE OXIDE COATED SURFACE OF SAID SUBSTRATE BEING EXPOSED TO SAID ETCHING SOLUTION, ELECTRICAL DETECTING MEANS DISPOSED IN OPERATIVE RELATION TO OPPOSITE SIDES OF SAID SUBSTRATE FOR DETECTING A SIGNAL GENERATED BY LIGHT IMPINGING ON A SURFACE OF SAID SUBSTRATE, AND LIGHT SOURCE MEANS FOR DIRECTING A BEAM OF LIGHT ON A PORTION OF THE EXPOSED OXIDE COATING TO BE ETCHED AWAY WHEREBY WHEN THE PROPER AMOUNT OF OXIDE HAS BEEN ETCHED AWAY, THE LIGHT BEAM WILL IMPINGE ON THE EXPOSED SURFACE OF SAID SEMICONDUCTOR TO PRODUCE A SIGNAL INDICATING THE ETCH ENDPOINT.
Claim 3
Dependent Claim
53 words
Apparatus as set forth in claim 1 wherein said electrical detecting means comprises a first contact electrically connected to the surface of the semiconductor which is not exposed to the solution, an electrode adapted to be disposed in said solution and a signal detecting means connected to said first contact and said electrode.
Claim 4
Dependent Claim
40 words
Apparatus as set forth in claim 1 wherein said light source means includes d.c. light source, means for periodically interrupting the light from said source and means for focusing said light on the exposed oxide coated surface of said substrate.
Claim 5
Independent Claim
89 words
A method for detecting the etch endpoint of the oxide coating on the surface of a semi-conductor substrate comprising, immersing said substrate in an etching solution with only one oxide coated surface thereof exposed to the etching solution, directing a chopped beam of d.c. light on a portion of the oxide coating to be etched away to generate an a.c. signal on the surface of said substrate when said beam makes contact with said substrate, sensing said signal, and applying said signal to means for indicating the etch endpoint.
Claim 6
Independent Claim
89 words
A method for detecting the etch endpoint of the oxide coating on the surface of a semi-conductor substrate comprising, immersing said substrate in an etching solution with only one oxide coated surface thereof exposed to the etching solution, directing a chopped beam of d.c. light on a portion of the oxide coating to be etched away to generate an a.c. signal on the surface of said substrate when said beam makes contact with said substrate, sensing said signal, and applying said signal to means for indicating the etch endpoint.
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) | 1978-03-31 | 1978-09-30 | 1979-04-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-31 | 1982-09-30 | 1983-04-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-31 | 1986-09-30 | 1987-04-01 | $7700.00 | Window Closed / Lapsed |