Method of forming small aperture
First Claim
1. A method of forming an aperture comprising:
- providing a substrate;
fabricating a column, said column extending from a frontside of said substrate;
depositing a metal layer on said frontside of said substrate, said metal layer covering a tip of said column but not covering a sidewall of said column;
applying at least one etchant which attacks said substrate, thereby causing a portion of said metal layer covering said tip of said column to lift off and forming a pit in said substrate; and
removing material from a backside of said substrate so as to form an aperture.
2 Assignments
0 Petitions
Accused Products
Abstract
A thick column is formed by masking and etching a substrate, and the column is thinned to a very small diameter (e.g., ≦5 nm) by oxidizing the column and removing the oxide layer. A metal layer is deposited on the surface of the substrate, and the column and substrate are etched to form a pit. The backside of the substrate is etched to form an aperture surrounded by the metal layer. Alternatively, the metal layer is removed and a dopant layer is implanted into the substrate, followed by the etching of the backside, leaving an aperture surrounded by the dopant layer. In a second alternative, the oxidized column is broken from the substrate, and the backside is etched, leaving an aperture surrounded by an oxide layer. These processes can be used to fabricate apertures of very small and reproducible dimensions for such instruments as near field scanning optical microscopes and scanning ion conductance microscopes.
23 Citations
21 Claims
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1. A method of forming an aperture comprising:
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providing a substrate; fabricating a column, said column extending from a frontside of said substrate; depositing a metal layer on said frontside of said substrate, said metal layer covering a tip of said column but not covering a sidewall of said column; applying at least one etchant which attacks said substrate, thereby causing a portion of said metal layer covering said tip of said column to lift off and forming a pit in said substrate; and removing material from a backside of said substrate so as to form an aperture. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of forming an aperture comprising:
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providing a substrate; fabricating a column, said column extending from a frontside of said substrate; forming an oxide layer on said column and said frontside; removing said column; and etching a backside of said substrate to form an aperture. - View Dependent Claims (15, 16)
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17. A method of forming an aperture comprising:
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providing a silicon substrate; depositing a metal dot on a surface of said silicon substrate; applying a first etchant to said surface so as to form a first column extending from a frontside of said substrate; oxidizing said first column to form a first oxide layer therein; removing said first oxide layer to form a column, the column being less thick than the first column; depositing a chromium layer on said frontside and a tip of said column; applying a second etchant to from a spike extending from said substrate; applying a third etchant to form a pit in said substrate; removing said chromium layer; implanting a layer of dopant in said frontside; and applying a fourth etchant to a backside of said substrate to form an aperture, said layer of dopant acting as an etch stop for said fourth etchant. - View Dependent Claims (18, 19)
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20. A method of forming an aperture comprising:
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providing a silicon substrate; depositing a metal dot on a surface of said silicon substrate; applying a first etchant to said surface so as to form a first column extending from a frontside of said substrate; oxidizing said first column to form a first oxide layer therein; removing said first oxide layer to form a column, the column being less thick than the first column; depositing a chromium layer on said frontside and a tip of said column; applying a second etchant to form a spike extending from said substrate; applying a third etchant to form a pit in said substrate; and applying a fourth etchant to a backside of said substrate to form an aperture, said chromium layer acting as an etch stop for said fourth etchant.
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21. A method of forming an aperture comprising:
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providing a silicon substrate; depositing a metal dot on a surface of said silicon substrate; applying a first etchant to said surface so as to form a column extending from a frontside of said substrate; oxidizing said column and said substrate to form an oxide layer in said column and in said frontside; removing said column; depositing a polyimide layer over said oxide layer; and applying a second etchant to a backside of said substrate to form an aperture, said oxide layer acting as an etch stop for said second etchant.
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Specification