US4354896A
Expired / Lapsed
US
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Formation of submicron substrate element
Assignee: Texas Instruments Inc
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Filing: 1980-08-05
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Granted: 1982-10-19
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Expires: 2000-08-05
Abstract
Abstract A method for patterning a submicrometer substrate element which is smaller than the reproducible resolution accuracy of optical lithography. A series of layers is deposited upon a top layer pattern using standard methods. An edge of the top layer is positioned at or near where the required submicrometer element is to be patterned. A cavity is formed in one of the intermediate layers by removing that intermediate layer in such a fashion that the layer underneath the edge of the top layer is removed. Next, a conformal layer is deposited upon the structure so that the conformal layer fills the cavity. Then the conformal layer is removed and each of the other layers is sequentially removed in such a fashion that only that portion of the conformal layer that occupied the cavity remains, together with any layers that occupy the space underneath the cavity. The remaining layers are the mask for further patterning.
Inventors
- 👤 William R. Hunter
- 👤 Al F. Tasch, Jr.
- 👤 Thomas C. Holloway
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:36
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/945; Y10S438/947
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
68 words
A method for patterning a submicrometer substrate element which comprises: (a) sequentially depositing a plurality of layers on the substrate surface; (b) forming a laterally extending submicrometer cavity by selectively removing an intermediate portion of said surface layers; (c) depositing a conformal layer of a material which fills said cavity; and (d) removing remaining portions of said surface layers and substrate material not covered by remaining conformal layer.
Claim 2
Independent Claim
68 words
A method for patterning a submicrometer substrate element which comprises: (a) sequentially depositing a plurality of layers on the substrate surface; (b) forming a laterally extending submicrometer cavity by selectively removing an intermediate portion of said surface layers; (c) depositing a conformal layer of a material which fills said cavity; and (d) removing remaining portions of said surface layers and substrate material not covered by remaining conformal layer.
Claim 3
Dependent Claim
26 words
The method as defined by claim 1, wherein said plurality of layers comprises a layer of nitride, a layer of oxide, and a layer of nitride.
Claim 4
Dependent Claim
37 words
The method as defined by claim 1, wherein said cavity is formed by: (i) patterning the top layer to form an edge; and (ii) selectively removing a portion of an intermediate layer located beneath said top layer.
Claim 5
Dependent Claim
19 words
The method as defined by claim 3, wherein said edge is formed by use of a selective anisotropic etch.
Claim 6
Dependent Claim
21 words
The method as defined by claim 3, wherein said portion of the intermediate layer is removed by means of an etch.
Claim 7
Dependent Claim
34 words
The method as defined by claim 5, wherein said etch comprises a wet etch whose etching properties are controlled to attack the said intermediate layer at a rate substantially greater than the other layers.
Claim 8
Dependent Claim
23 words
The method as defined by claim 1, wherein said depositing of said conformal layer in said cavity is accomplished by chemical vapor deposition.
Claim 9
Dependent Claim
23 words
The method as defined by claim 1 wherein said step of selectively removing said conformal layer is accomplished by means of an etch.
Claim 10
Dependent Claim
22 words
The method as defined by claim 1, wherein said step of removing said surface layers is accomplished by means of an etch.
Claim 11
Independent Claim
88 words
A method for patterning a submicrometer substrate element which comprises: (a) sequentially depositing a plurality of layers on the substrate surface and patterning the top layer to form an edge; (b) forming a laterally extending submicrometer cavity by selectively removing a portion of one of said surface layers beneath said edge; (c) depositing a conformal layer of a material which fills said cavity; and (d) selectively removing (i) said conformal layer except in said cavity and (ii) said surface layers except that covered by the remaining conformal layer.
Claim 12
Independent Claim
88 words
A method for patterning a submicrometer substrate element which comprises: (a) sequentially depositing a plurality of layers on the substrate surface and patterning the top layer to form an edge; (b) forming a laterally extending submicrometer cavity by selectively removing a portion of one of said surface layers beneath said edge; (c) depositing a conformal layer of a material which fills said cavity; and (d) selectively removing (i) said conformal layer except in said cavity and (ii) said surface layers except that covered by the remaining conformal layer.
Claim 13
Dependent Claim
26 words
The method as defined by claim 10, wherein said plurality of layers comprises a layer of nitride, a layer of oxide, and a layer of nitride.
Claim 14
Dependent Claim
19 words
The method as defined by claim 10, wherein said edge is formed by use of a selective anisotropic etch.
Claim 15
Dependent Claim
27 words
The method as defined by claim 10 wherein said step of removing a portion of one of said surface layers is accomplished by means of an etch.
Claim 16
Dependent Claim
34 words
The method as defined by claim 13, wherein said etch comprises a wet etch whose etching properties are controlled to attack the said intermediate layer at a rate substantially greater than the other layers.
Claim 17
Dependent Claim
23 words
The method as defined by claim 10 wherein said depositing of said conformal layer in said cavity is accomplished by chemical vapor deposition.
Claim 18
Dependent Claim
23 words
The method as defined by claim 10, wherein said step of selectively removing said conformal layer is accomplished by means of an etch.
Claim 19
Dependent Claim
22 words
The method as defined by claim 10 wherein said step of removing said surface layers is accomplished by means of an etch.
Claim 20
Independent Claim
194 words
A method for patterning a submicrometer polysilicon element which comprises: (a) sequentially depositing bottom layer of nitride, a layer of oxide, and a top layer of nitride on top of the polysilicon to be patterned; (b) patterning the top nitride layer to form an edge positioned where the submicrometer polysilicon element is to be formed; (c) selectively removing a portion of the oxide layer so that a submicrometer cavity is formed beneath said edge of the top nitride layer; (d) depositing a conformal layer of polysilicon on the resulting composite so that the polysilicon fills said cavity and covers the remaining exposed areas; (e) subjecting the conformal polysilicon layer to an anisotropic etch so that only the exposed polysilicon is removed, leaving said cavity filled; (f) selectively removing the top nitride layer; (g) removing the oxide layer; (h) selectively removing the exposed portions of the bottom nitride layer with an anisotropic etch so that only the nitride underneath the remaining conformal polysilicon remains; and (i) subjecting remaining structure to a selective, anisotropic etch so that only the exposed polysilicon is removed, leaving the polysilicon underneath the nitride as said submicrometer element to be formed.
Claim 21
Independent Claim
194 words
A method for patterning a submicrometer polysilicon element which comprises: (a) sequentially depositing bottom layer of nitride, a layer of oxide, and a top layer of nitride on top of the polysilicon to be patterned; (b) patterning the top nitride layer to form an edge positioned where the submicrometer polysilicon element is to be formed; (c) selectively removing a portion of the oxide layer so that a submicrometer cavity is formed beneath said edge of the top nitride layer; (d) depositing a conformal layer of polysilicon on the resulting composite so that the polysilicon fills said cavity and covers the remaining exposed areas; (e) subjecting the conformal polysilicon layer to an anisotropic etch so that only the exposed polysilicon is removed, leaving said cavity filled; (f) selectively removing the top nitride layer; (g) removing the oxide layer; (h) selectively removing the exposed portions of the bottom nitride layer with an anisotropic etch so that only the nitride underneath the remaining conformal polysilicon remains; and (i) subjecting remaining structure to a selective, anisotropic etch so that only the exposed polysilicon is removed, leaving the polysilicon underneath the nitride as said submicrometer element to be formed.
Claim 22
Dependent Claim
42 words
The method as defined by claim 18, wherein said step of selectively removing a portion of the oxide layer is accomplished by contact with a wet etch whose etching properties are controlled to attack oxide at a rate substantially greater than nitride.
Claim 23
Independent Claim
192 words
A method for patterning a submicrometer polysilicon element which comprises: (a) sequentially depositing bottom layer of nitride, a layer of oxide, and a top layer of nitride on top of the polysilicon to be patterned; (b) patterning the top nitride layer to form an edge positioned where the submicrometer polysilicon element is to be formed; (c) selectively removing a portion of the oxide layer so that a submicrometer cavity is formed beneath said edge of the top nitride layer; (d) depositing a conformal layer of nitride on the resulting composite so that the conformal nitride fills said cavity and covers the remaining exposed areas; (e) subjecting the conformal nitride layer to an anisotropic etch so that only the exposed nitride and top nitride layer are removed, leaving conformal nitride that filled said cavity; (f) removing the oxide layer; (g) selectively removing the exposed portions of the bottom nitride layer with an anisotropic etch so that only the nitride underneath the remaining conformal nitride remains; and (h) subjecting remaining structure to a selective, anisotropic etch so that only the exposed polysilicon is removed, leaving the nitride as said submicrometer element to be formed.
Claim 24
Independent Claim
192 words
A method for patterning a submicrometer polysilicon element which comprises: (a) sequentially depositing bottom layer of nitride, a layer of oxide, and a top layer of nitride on top of the polysilicon to be patterned; (b) patterning the top nitride layer to form an edge positioned where the submicrometer polysilicon element is to be formed; (c) selectively removing a portion of the oxide layer so that a submicrometer cavity is formed beneath said edge of the top nitride layer; (d) depositing a conformal layer of nitride on the resulting composite so that the conformal nitride fills said cavity and covers the remaining exposed areas; (e) subjecting the conformal nitride layer to an anisotropic etch so that only the exposed nitride and top nitride layer are removed, leaving conformal nitride that filled said cavity; (f) removing the oxide layer; (g) selectively removing the exposed portions of the bottom nitride layer with an anisotropic etch so that only the nitride underneath the remaining conformal nitride remains; and (h) subjecting remaining structure to a selective, anisotropic etch so that only the exposed polysilicon is removed, leaving the nitride as said submicrometer element to be formed.
Claim 25
Dependent Claim
42 words
The method as defined by claim 20, wherein said step of selectively removing a portion of the oxide layer is accomplished by contact with a wet etch whose etching properties are controlled to attack oxide at a rate substantially greater than nitride.
Claim 26
Dependent Claim
63 words
The method as defined by claim 21, wherein said step of depositing a series of layers consists of depositing a series of layers of nitride, oxide, nitride and oxide and said step of removing the polysilicon layer polysilicon layer with an anisotropic etch is preceded by a step wherein the bottom bottom oxide layer is removed by an anisotropic etch selective against polysilicon.
References Cited (Backward Citations)
US3977925A
Cited
US4256514A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-10-18 | 1986-04-19 | 1986-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-18 | 1990-04-19 | 1990-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-18 | 1994-04-19 | 1994-10-19 | $7700.00 | Window Closed / Lapsed |