US5127984A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Rapid wafer thinning process
Assignee: Avago Technologies International Sales Pte Ltd
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Filing: 1991-05-02
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Granted: 1992-07-07
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Expires: 2011-05-02
Abstract
Abstract A method for thinning a Gallium Arsenide (GaAs) layer on the backside of a wafer substrate is provided. The method involves spraying an etchant solution including NH 4 OH and H 2 O 2 , preferably in a 1:4 ratio, onto the GaAs layer as the wafer is rotated at approximately 2000 rpm. The etchant is sprayed through a plurality of spray nozzles. The process is capable of thinning a GaAs layer by about 500 μm in approximately 14 to 18 minutes, depending on the etchant temperature and composition.
Inventors
- 👤 Chang-Hwang Hua
- 👤 Ding Y. S. Day
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 18:13
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/646
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
126 words
A method for uniformly thinning a GaAs layer on the backside of a semiconductor layer, comprising the steps of: measuring the thickness of a GaAs layer on a wafer; mounting the wafer on a carrier, wherein the wafer has a frontside and a backside, the wafer being mounted so that its frontside faces the carrier and the wafer backside is exposed; attaching the carrier to a rotatable chuck, the chuck being located below a spraying means which is substantially directed at the backside of the wafer; preparing an etchant comprising NH 4 OH and H 2 O 2 ; rotating the chuck; spraying the etchant out of the spraying means onto the wafer backside during the rotating step until the desired GaAs layer thickness is obtained.
Claim 2
Independent Claim
126 words
A method for uniformly thinning a GaAs layer on the backside of a semiconductor layer, comprising the steps of: measuring the thickness of a GaAs layer on a wafer; mounting the wafer on a carrier, wherein the wafer has a frontside and a backside, the wafer being mounted so that its frontside faces the carrier and the wafer backside is exposed; attaching the carrier to a rotatable chuck, the chuck being located below a spraying means which is substantially directed at the backside of the wafer; preparing an etchant comprising NH 4 OH and H 2 O 2 ; rotating the chuck; spraying the etchant out of the spraying means onto the wafer backside during the rotating step until the desired GaAs layer thickness is obtained.
Claim 3
Dependent Claim
28 words
The method of claim 1 wherein the spraying step includes the step of depositing approximately between 200 to 400 mls of etchant per minute onto the wafer backside.
Claim 4
Dependent Claim
15 words
The method of claim 2 wherein the spraying means includes at least three spray nozzles.
Claim 5
Dependent Claim
37 words
The method of claim 1 wherein the ratio of NH 4 OH to H 2 O 2 in the etchant is between 1:1 and 1:10 and the H 2 O 2 is at least about 15% (V/V).
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein the ratio of NH 4 OH to H 2 O 2 is 1:4.
Claim 7
Dependent Claim
30 words
The method of claim 1 wherein the chuck has an axis of rotation, the wafer carrier being attached to the chuck directly on top of the chuck's axis of rotation.
Claim 8
Dependent Claim
16 words
The method of claim 1 wherein the spraying step lasts for between five and twenty minutes.
Claim 9
Dependent Claim
22 words
The method of claim 1 wherein the rotation speed of the chuck in the rotating step is between 1000 and 2000 rpm.
Claim 10
Dependent Claim
20 words
The method of claim 8 wherein the rotation speed of the chuck in the rotating step is approximately 2000 rpm.
Claim 11
Dependent Claim
16 words
The method of claim 1 further comprising the step of controlling the temperature of the etchant.
Claim 12
Dependent Claim
17 words
The method of claim 10 wherein the temperature of the etchant is maintained at approximately 45° C.
Claim 13
Independent Claim
92 words
A method of uniformly thinning a GaAs layer on the backside of a semiconductor wafer comprising the steps of: determining the thickness of a GaAs layer on the backside of a semiconductor wafer; mounting said wafer on a carrier, exposing said layer; and rotating said carrier at a speed of at least 1000 rpm while spraying an etchant comprising NH 4 OH and H 2 O 2 onto said layer from a spraying means positioned above said carrier for a period of time sufficient to etch the desired thickness of GaAs away.
Claim 14
Independent Claim
92 words
A method of uniformly thinning a GaAs layer on the backside of a semiconductor wafer comprising the steps of: determining the thickness of a GaAs layer on the backside of a semiconductor wafer; mounting said wafer on a carrier, exposing said layer; and rotating said carrier at a speed of at least 1000 rpm while spraying an etchant comprising NH 4 OH and H 2 O 2 onto said layer from a spraying means positioned above said carrier for a period of time sufficient to etch the desired thickness of GaAs away.
Claim 15
Dependent Claim
26 words
The method of claim 12 wherein the spraying step includes the step of depositing approximately between 200 to 400 mls of etchant onto the wafer backside.
Claim 16
Dependent Claim
15 words
The method of claim 13 wherein the spraying means includes at least three spray nozzles.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-07-07 | 1996-01-06 | 1996-07-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-07-07 | 2000-01-06 | 2000-07-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-07-07 | 2004-01-06 | 2004-07-07 | $7700.00 | Window Closed / Lapsed |