US5691230A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Technique for producing small islands of silicon on insulator
Assignee: Micron Technology Inc
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Filing: 1996-09-04
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Granted: 1997-11-25
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Expires: 2016-09-04
Abstract
Abstract Using sub-micron technology, silicon on insulator (SOI) rows and islands are formed in a silicon substrate. Trenches are directionally-etched in the silicon substrate, leaving rows of silicon between the trenches. Silicon nitride is then deposited over the trenches, extending partly down the sides of the trenches. An isotropic chemical etch is then used to partially undercut narrow rows of silicon in the substrate. A subsequent oxidation step fully undercuts the rows of silicon, isolating the silicon rows from adjacent active areas. Devices, such as transistors for CMOS and DRAMs, are then formed in active areas, wherein the active areas are defined on the silicon rows by LOCal Oxidation of Silicon (LOCOS).
Inventors
- 👤 Leonard Forbes
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 15:38
CPC Classifications
H; H10; H10P; H10P14/00; H10P14/60; H10P14/61; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10W10/0121; H10W10/0123; H10W10/061; H10W10/10; H10W10/13; H10W10/181; Y; Y10; Y10S; Y10S148/00; Y10S148/05
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
65 words
A method for manufacturing a silicon on insulator substrate, comprising the steps of: directionally etching a silicon substrate, to form a plurality of trenches between protruding silicon rows; forming a silicon nitride cap on the silicon rows, extending partway down the sides of the trenches; isotropically etching the trenches, to partially undercut the silicon rows; and oxidizing the substrate, to fully undercut the silicon rows.
Claim 2
Independent Claim
65 words
A method for manufacturing a silicon on insulator substrate, comprising the steps of: directionally etching a silicon substrate, to form a plurality of trenches between protruding silicon rows; forming a silicon nitride cap on the silicon rows, extending partway down the sides of the trenches; isotropically etching the trenches, to partially undercut the silicon rows; and oxidizing the substrate, to fully undercut the silicon rows.
Claim 3
Dependent Claim
23 words
The method of claim 1, wherein the silicon substrate has a {100} crystallographic orientation and the directional etch is in the <100> direction.
Claim 4
Dependent Claim
14 words
The method of claim 1, wherein the directional etchant comprises a reactive ion etch.
Claim 5
Dependent Claim
12 words
The method of claim 1, wherein the isotropic etchant comprises hydrofluoric acid.
Claim 6
Dependent Claim
18 words
The method of claim 1, wherein the silicon rows have a width dimension of one micron or less.
Claim 7
Dependent Claim
18 words
The method of claim 1, wherein the silicon rows have a width dimension of 0.25 microns or less.
Claim 8
Dependent Claim
31 words
The method of claim 1, wherein the directional etch is approximately as deep as the width of the silicon rows and approximately as wide as the width of the silicon rows.
Claim 9
Dependent Claim
28 words
The method of claim 1, wherein the oxidizing step comprises oxidizing the substrate in a wet oxidizing ambient at a temperature of approximately 900 to 1,100 degrees Celsius.
Claim 10
Dependent Claim
26 words
The method of claim 1, and further comprising the step of: defining a plurality of active areas on the silicon rows by local oxidation of silicon.
Claim 11
Dependent Claim
23 words
The method of claim 9, and further comprising the step of: forming a transistor on each of a plurality of the active areas.
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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) | 2000-11-24 | 2001-05-26 | 2001-11-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-11-24 | 2005-05-26 | 2005-11-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-11-24 | 2009-05-26 | 2009-11-25 | $7700.00 | Window Closed / Lapsed |