US4840701A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Etching apparatus and method
Assignee: STMicroelectronics NV
•
Filing: 1988-06-23
•
Granted: 1989-06-20
•
Expires: 2008-06-23
Abstract
Abstract An etching apparatus for the selective etching of e.g. single crystal silicon is described. The apparatus includes a tank for receiving a quantity of liquid etchant, the tank being provided with means for injecting oxygen, nitrogen or mixtures thereof into the etchant. Stirrers circulate the etchant around the bath. Gas injection has been found to improve the quality of the etched product and to provide control of the etching process.
Inventors
- 👤 Ronald C. Stern
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 12:42
CPC Classifications
H; H10; H10P; H10P90/00; H10P90/12; H10P90/126; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/644
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
60 words
A liquid etching apparatus, including a sealable container for receiving a quantity of liquid etchant and having means for mounting a plurality of single crystal semiconductor substrates in contact with the etchant, means for circulating and mixing the etchant within the container, and means for injecting oxygen, an inert gas or mixtures thereof into the etchant adjacent the semiconductor substrates.
Claim 2
Dependent Claim
60 words
A liquid etching apparatus, including a sealable container for receiving a quantity of liquid etchant and having means for mounting a plurality of single crystal semiconductor substrates in contact with the etchant, means for circulating and mixing the etchant within the container, and means for injecting oxygen, an inert gas or mixtures thereof into the etchant adjacent the semiconductor substrates.
Claim 3
Dependent Claim
41 words
A liquid etching apparatus as claimed in claim 1, wherein said circulating and mixing means comprises one or more stirrer whereby, in use, vortices are formed in the etchant such that gas is drawn from the etchant surface into the etchant.
Claim 4
Dependent Claim
18 words
A liquid etching apparatus as claimed in claim 2, wherein cooling means is provided for condensing evaporated etchant.
Claim 5
Independent Claim
51 words
A method of etching a single crystal semiconductor substrate, the method including exposing a selected region of the substrate to a liquid etch, agitating the etchant adjacent the substrate, and injecting oxygen, an inert gas or mixtures thereof into the etchant adjacent the substrate thereby achieving uniform etching of the substrate.
Claim 6
Independent Claim
51 words
A method of etching a single crystal semiconductor substrate, the method including exposing a selected region of the substrate to a liquid etch, agitating the etchant adjacent the substrate, and injecting oxygen, an inert gas or mixtures thereof into the etchant adjacent the substrate thereby achieving uniform etching of the substrate.
Claim 7
Dependent Claim
12 words
A method as claimed in claim 4 wherein the semiconductor is silicon.
Claim 8
Dependent Claim
19 words
A method as claimed in claim 5, wherein the etchant is a mixture of water potassium hydroxide and isopropanol.
Claim 9
Dependent Claim
20 words
A method as claimed in claim 6 wherein the potassium hydroxide concentrate in the etchant is at least 25% wt/vol.
Claim 10
Dependent Claim
13 words
A method as claimed in claim 7, wherein the inert gas is nitrogen.
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) | 1992-06-19 | 1992-12-19 | 1993-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-06-19 | 1996-12-19 | 1997-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-06-19 | 2000-12-19 | 2001-06-20 | $7700.00 | Window Closed / Lapsed |