Patent EP0265638A2 successfully refreshed from Google Patents.
EP0265638A2
Expired / Lapsed
EP
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Lithographic image size reduction
Assignee: International Business Machines Corp
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Filing: 1987-09-08
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Granted: —
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Expires: 2007-09-08
Abstract
Abstract Disclosed is a process for reducing lithographic image size for integrated circuit manufacture. A mask (14) of photosensitive material having an opening (20) of a minimum size (A) dictated by the limits of lithography is formed on a substrate (10). Reduction in the image size is achieved by establishing sidewalls (24) to the interior vertical surfaces of the opening by depositing a conformal layer (22), followed by anisotropic etching. The dimension (C) of the new opening is reduced by the combined thickness of the two opposite insulator sidewalls. In a specific direct application of the disclosed process, a photomask/stencil having a pattern of openings of a minimum size smaller than possible by lithography, per se, is formed.
Inventors
- 👤 Nicholas James Giammarco
- 👤 Alexander Gimpelson
- 👤 George Anthony Kaplita
- 👤 Alexander Daniel Lopata
- 👤 Anthony Francis Scaduto
- 👤 Joseph Francis Shepard
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 04:47
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/693; H10P50/696; H10P50/695; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; H10P76/4088; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/947; Y10T; Y10T428/00; Y10T428/24; Y10T428/24273; Y10T428/24322
Claims Analysis
Total Claims: 35
Claim 1
Independent Claim
88 words
Process for forming a mask having an opening of a size smaller than obtainable by lithography, comprising: providing a substrate coated with a photosensitive material; patterning the photosensitive material to form an opening therein, said opening having substantially vertical walls and minimum size dictated by resolution limit of lithography; forming a conformal layer of a material on the resulting structure including said vertical walls; and anisotropically etching said conformal layer to provide said conformal layer material on said vertical walls whereby said size of said opening is reduced.
Claim 2
Dependent Claim
88 words
Process for forming a mask having an opening of a size smaller than obtainable by lithography, comprising: providing a substrate coated with a photosensitive material; patterning the photosensitive material to form an opening therein, said opening having substantially vertical walls and minimum size dictated by resolution limit of lithography; forming a conformal layer of a material on the resulting structure including said vertical walls; and anisotropically etching said conformal layer to provide said conformal layer material on said vertical walls whereby said size of said opening is reduced.
Claim 3
Dependent Claim
20 words
The process as in claim 1 wherein said substrate is selected from a group consisting of semiconductor, insulator and conductor.
Claim 4
Dependent Claim
20 words
The process as in claim 1 wherein said substrate is composed of either silicon, glass, metal or a combination thereof.
Claim 5
Dependent Claim
25 words
The process as in claim 1 wherein said conformal layer material is silicon dioxide, Si x O y , silicon nitride, silicon oxynitride or polysilicon.
Claim 6
Dependent Claim
20 words
The process as in claim 1 wherein said material is Si x O y obtained by plasma deposition of hexamethyldisilazane.
Claim 7
Dependent Claim
12 words
The process as in claim 1 wherein said photosensitive material is photoresist.
Claim 8
Dependent Claim
23 words
The process as in claim 1 further comprising forming on said substrate a readily removable layer prior to coating with said photosensitive layer.
Claim 9
Dependent Claim
18 words
The process as in claim 1 further comprising hardening said photosensitive material prior to forming said conformal layer.
Claim 10
Dependent Claim
23 words
The process as in claim 1 wherein the size of said opening is reduced by approximately twice the thickness of said conformal layer.
Claim 11
Dependent Claim
20 words
The process as in claim 7 wherein said photosensitive layer is thick compared to the thickness of said removable layer.
Claim 12
Dependent Claim
73 words
A process for reducing the size of a lithographic image in a mask material comprising: forming on a substrate a mask material having at least one opening of minimum size A determined by the resolution limit of lithographic exposure tooling, said opening having substantially vertical interior walls; and establishing sidewalls of a material of a thickness B on said walls, whereby the new size C of said opening is at least approximately A-2B.
Claim 13
Dependent Claim
73 words
A process for reducing the size of a lithographic image in a mask material comprising: forming on a substrate a mask material having at least one opening of minimum size A determined by the resolution limit of lithographic exposure tooling, said opening having substantially vertical interior walls; and establishing sidewalls of a material of a thickness B on said walls, whereby the new size C of said opening is at least approximately A-2B.
Claim 14
Dependent Claim
21 words
The process as recited in claim 11 wherein the percentage reduction in the size A of said opening is about 2B/A.
Claim 15
Dependent Claim
40 words
The process as recited in claim 11 wherein said sidewall material has a lower etch rate than that of said substrate enabling said mask material in combination with said sidewalls to function as an etch mask for etching said substrate.
Claim 16
Dependent Claim
38 words
The process as recited in claim 11 wherein the step of establishing sidewalls comprises: forming a conformal layer of said sidewall material; and anisotropically etching to remove said sidewall material from everywhere except the walls of said opening.
Claim 17
Dependent Claim
144 words
Process for forming a mask on a substrate surface for integrated circuit manufacture comprising: providing a substrate covered with a relatively thick layer of a first material; coating said first material with a photosensitive layer having an opening of a minimum size dictated by the resolution limit of lithography, said opening having substantially vertical surfaces; depositing a conformal layer of an insulator material on said first material including said vertical surfaces and on the substrate exposed by said opening; anisotropically etching to remove said conformal layer from everywhere except said walls of said opening, thereby reducing the size of said opening by approximately twice the thickness of said conformal layer; and anisotropically etching said first material layer to transfer thereto an image of said opening of reduced size in said photosensitive layer and transform said first material layer into a mask for said substrate.
Claim 18
Dependent Claim
144 words
Process for forming a mask on a substrate surface for integrated circuit manufacture comprising: providing a substrate covered with a relatively thick layer of a first material; coating said first material with a photosensitive layer having an opening of a minimum size dictated by the resolution limit of lithography, said opening having substantially vertical surfaces; depositing a conformal layer of an insulator material on said first material including said vertical surfaces and on the substrate exposed by said opening; anisotropically etching to remove said conformal layer from everywhere except said walls of said opening, thereby reducing the size of said opening by approximately twice the thickness of said conformal layer; and anisotropically etching said first material layer to transfer thereto an image of said opening of reduced size in said photosensitive layer and transform said first material layer into a mask for said substrate.
Claim 19
Dependent Claim
32 words
The process as recited in claim 15 further comprising removing said photosensitive layer and the sidewalls of said conformal layer associated with the opening therein following said etching of said first material.
Claim 20
Dependent Claim
34 words
The process as recited in claim 16 further comprising forming a release layer on said first material prior to coating said photosensitive layer to facilitate removal of said photosensitive layer and said associated sidewalls.
Claim 21
Dependent Claim
19 words
The process as recited in claim 17 further comprising hardening said photosensitive layer prior to depositing said conformal layer.
Claim 22
Dependent Claim
13 words
The process as in claim 18 wherein said conformal layer is plasma-deposited hexamethlydisilazane.
Claim 23
Dependent Claim
31 words
The process as in claim 19 further comprising using said mask anisotropically etching said substrate to form an extremely narrow and deep trench of a width equivalent to said reduced size.
Claim 24
Dependent Claim
55 words
A photomask comprising: a substrate of a first material; a layer of a second material having at least one opening formed on said substrate, said opening having substantially vertical walls; and sidewalls of a third material of a common and uniform thickness formed on all of said vertical walls, decreasing the size of said opening.
Claim 25
Dependent Claim
55 words
A photomask comprising: a substrate of a first material; a layer of a second material having at least one opening formed on said substrate, said opening having substantially vertical walls; and sidewalls of a third material of a common and uniform thickness formed on all of said vertical walls, decreasing the size of said opening.
Claim 26
Dependent Claim
20 words
The photomask as in claim 21 wherein said size of said opening is equivalent to the resolution limit of lithography.
Claim 27
Dependent Claim
24 words
The photomask as in claim 21 wherein the decrease in size of said opening is equal to about twice the thickness of said sidewalls.
Claim 28
Dependent Claim
12 words
The photomask as in claim 21 wherein said first material is glass.
Claim 29
Dependent Claim
13 words
The photomask as in claim 24 wherein said second material is hardened photoresist.
Claim 30
Dependent Claim
30 words
The photomask as in claim 25 wherein said third material is selected from a group consisting of silicon dioxide, silicon nitride, Si x O x , silicon oxynitride and polysilicon.
Claim 31
Dependent Claim
55 words
A stencil comprising: a rigid layer of a first material having therein at least one opening of linear dimension A, said opening having substantially vertical walls; and a sidewall of a second material of a common and uniform thickness B established on all of said walls, whereby said dimension A of said opening is reduced.
Claim 32
Dependent Claim
55 words
A stencil comprising: a rigid layer of a first material having therein at least one opening of linear dimension A, said opening having substantially vertical walls; and a sidewall of a second material of a common and uniform thickness B established on all of said walls, whereby said dimension A of said opening is reduced.
Claim 33
Dependent Claim
19 words
The stencil as in claim 27 wherein said dimension A is the smallest dimension that is obtainable by lithography.
Claim 34
Dependent Claim
13 words
The stencial as in claim 27 wherein said first material is hardened photoresist.
Claim 35
Dependent Claim
30 words
The stencial as in claim 29 wherein said second material is selected from the group consisting of silicon dioxide, Si x O x , silicon nitride, silicon oxynitride and polysilicon.
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