Lithographic image size reduction
First Claim
1. 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.
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Accused Products
Abstract
Disclosed is a process for reducing lithographic image size for integrated circuit manufacture. A mask of photosensitive material having an opening of a minimum size dictated by the limits of lithography is formed on a substrate. Reduction in the image size is achieved by establishing sidewalls to the interior vertical surfaces of the opening by depositing a conformal layer, followed by anisotropic etching. The dimension of the 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.
217 Citations
20 Claims
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1. Process for forming a mask having an opening of a size smaller than obtainable by lithography, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for reducing the size of a lithographic image in a mask material comprising:
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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. - View Dependent Claims (12, 13, 14)
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15. Process for forming a mask on a substrate surface for integrated circuit manufacture comprising:
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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. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification