US5686345A
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Trench mask for forming deep trenches in a semiconductor substrate, and method of using same
Assignee: International Business Machines Corp
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Filing: 1996-01-30
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Granted: 1997-11-11
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Expires: 2016-01-30
Abstract
Abstract A method for forming high aspect ratio, deep trenches in a semiconductor substrate with a composite etch mask structure including a thermally grown oxide surface layer as a plasma etch mask.
Inventors
- 👤 David Laurant Harmon
- 👤 Nancy Tovey Pascoe
- 👤 John Francis Rembetski
- 👤 Pai-Hung Pan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:20
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/692; Y; Y10; Y10S; Y10S148/00; Y10S148/05
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
103 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening extending through exposed opposing side faces of said polysilicon oxide layer and said polysilicon layer, and said opening exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface.
Claim 2
Independent Claim
103 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening extending through exposed opposing side faces of said polysilicon oxide layer and said polysilicon layer, and said opening exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface.
Claim 3
Dependent Claim
19 words
The method of claim 1, wherein said etching of said semiconductor substrate comprises forming a groove with anisotropic etching.
Claim 4
Dependent Claim
17 words
The method of claim 2, wherein said anisotropic etching comprises a reactive ion etching selective for silicon.
Claim 5
Independent Claim
96 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening therethrough exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface, wherein said trench has an aspect ratio greater than 10:1.
Claim 6
Independent Claim
96 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening therethrough exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface, wherein said trench has an aspect ratio greater than 10:1.
Claim 7
Independent Claim
97 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening therethrough exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface, wherein said trenches have width openings of less than 0.5 μm.
Claim 8
Independent Claim
97 words
A method for forming a trench in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a polysilicon layer on said semiconductor surface; (c) forming a polysilicon oxide layer on said polysilicon layer; (d) patterning said polysilicon oxide layer and said polysilicon layer to form at least one opening therethrough exposing a portion of said semiconductor surface; and (e) etching said semiconductor substrate through said opening to form a trench extending into said substrate from said semiconductor surface, wherein said trenches have width openings of less than 0.5 μm.
Claim 9
Dependent Claim
12 words
The method of claim 1, wherein said semiconductor substrate is monocrystalline silicon.
Claim 10
Independent Claim
117 words
A method for forming trenches in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a silicon dioxide layer on said semiconductor surface; (c) forming a silicon nitride layer on said silicon dioxide layer; (d) forming a polysilicon layer on said silicon nitride layer; (e) forming a polysilicon oxide layer on said polysilicon layer; (f) patterning all of said polysilicon oxide layer, said polysilicon layer, said silicon nitride layer and said silicon dioxide layer to form a pattern of sub-micron width openings therethrough exposing portions of said semiconductor surface; and (g) etching said semiconductor substrate through said openings to form trenches extending into said substrate from said semiconductor surface.
Claim 11
Independent Claim
117 words
A method for forming trenches in a semiconductor substrate, comprising the steps of: (a) providing a semiconductor substrate having a surface; (b) forming a silicon dioxide layer on said semiconductor surface; (c) forming a silicon nitride layer on said silicon dioxide layer; (d) forming a polysilicon layer on said silicon nitride layer; (e) forming a polysilicon oxide layer on said polysilicon layer; (f) patterning all of said polysilicon oxide layer, said polysilicon layer, said silicon nitride layer and said silicon dioxide layer to form a pattern of sub-micron width openings therethrough exposing portions of said semiconductor surface; and (g) etching said semiconductor substrate through said openings to form trenches extending into said substrate from said semiconductor surface.
Claim 12
Dependent Claim
19 words
The method of claim 7, wherein said etching of said semiconductor substrate comprises forming a groove with anisotropic etching.
Claim 13
Dependent Claim
17 words
The method of claim 8, wherein said anisotropic etching comprises a reactive ion etching selective for silicon.
Claim 14
Dependent Claim
15 words
The method of claim 7, wherein said trenches has an aspect ratio greater than 10:1.
Claim 15
Dependent Claim
16 words
The method of claim 7, wherein said sub-micron width openings each are less than 0.5 μm.
Claim 16
Dependent Claim
12 words
The method of claim 7, wherein said semiconductor substrate is monocrystalline silicon.
Claim 17
Dependent Claim
32 words
The method of claim 7, wherein said step (e) of forming said polysilicon oxide layer on said polysilicon layer comprises thermally oxidizing a portion of said polysilicon layer formed in step (d).
Claim 18
Dependent Claim
38 words
The method of claim 13, wherein said polysilicon layer is formed with an original thickness in step (d) and said thermal oxidizing of said polysilicon layer extends through approximately 70% of said original thickness of said polysilicon layer.
Claim 19
Dependent Claim
26 words
The method of claim 13, wherein said thermal oxidizing comprises subjecting said polysilicon layer to steam oxidation at a temperature of about 900° to 1,000° C.
Claim 20
Dependent Claim
148 words
Method for forming deep trenches in a semiconductor substrate, comprising the steps of: depositing a first polysilicon layer having a first thickness on a semiconductor substrate; thermally oxidizing at least a predominant portion but not all of said first polysilicon layer to form a polysilicon oxide layer thereby leaving a second polysilicon layer with a second thickness; said second thickness of said second polysilicon layer being less than said first thickness of said first polysilicon layer; patterning said polysilicon oxide layer and said second polysilicon layer to form a pattern of sub-micron width openings extending through exposed opposing side faces of said polysilicon oxide layer and said second polysilicon layer, and said openings exposing portions of a surface of said semiconductor substrate; and anisotropically etching said semiconductor surface through said openings to form trenches having sub-micron width openings, said trenches extending into said substrate from said semiconductor surface.
Claim 21
Dependent Claim
148 words
Method for forming deep trenches in a semiconductor substrate, comprising the steps of: depositing a first polysilicon layer having a first thickness on a semiconductor substrate; thermally oxidizing at least a predominant portion but not all of said first polysilicon layer to form a polysilicon oxide layer thereby leaving a second polysilicon layer with a second thickness; said second thickness of said second polysilicon layer being less than said first thickness of said first polysilicon layer; patterning said polysilicon oxide layer and said second polysilicon layer to form a pattern of sub-micron width openings extending through exposed opposing side faces of said polysilicon oxide layer and said second polysilicon layer, and said openings exposing portions of a surface of said semiconductor substrate; and anisotropically etching said semiconductor surface through said openings to form trenches having sub-micron width openings, said trenches extending into said substrate from said semiconductor surface.
Claim 22
Dependent Claim
15 words
The method of claim 16, wherein said trenches has an aspect ratio greater than 10:1.
Claim 23
Dependent Claim
16 words
The method of claim 16, wherein said trenches have width openings of less than 0.5 μm.
Claim 24
Dependent Claim
26 words
The method of claim 16, wherein said second thickness of said second polysilicon layer is approximately 30% of said first thickness of said first polysilicon layer.
References Cited (Backward Citations)
US5008210A
Cited
US5118384A
Cited
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