Formation of microstructures by multiple level deep X-ray lithography with sacrificial metal layers
First Claim
1. A method of forming micromechanical structures comprising the steps of:
- (a) providing a plating base on a surface of a substrate;
(b) applying a photoresist in a layer onto the plating base;
(c) exposing the photoresist in a pattern to radiation to render the photoresist dissolvable in a pattern;
(d) removing the dissolvable photoresist;
(e) electroplating a first layer of a primary metal onto the plating base in the area from which the photoresist has been removed;
(f) removing the remainder of the photoresist;
(g) electroplating a first layer of a secondary metal onto the plating base to cover and surround the first layer of the primary metal, the secondary metal chosen so that it can be differentially etched without substantially etching the primary metal;
(h) machining the exposed surface of the secondary metal down to a flat surface to a selected height which exposes the first layer of the primary metal.
1 Assignment
0 Petitions
Accused Products
Abstract
Complex metal structures are formed in microminiature dimensions utilizing multiple mask exposures which are capable of producing substantially arbitrary three-dimensional shapes. A first layer of a primary metal is electroplated onto an exposed plating base to fill a void in a photoresist, the photoresist is removed, and a secondary metal, which can constitute a sacrificial metal, is electroplated over the first layer and the plating base. The exposed surface of the deposited secondary metal is then machined down to a height which exposes the first metal to produce a substantially flat, uniform surface extending across both the primary and secondary metals. The secondary metal facilitates machining of the primary and secondary metals because of these mechanical stability provided by the secondary metal to the primary metal. After the first layers of the primary and secondary metals have been machined, another photoresist layer can be applied over the primary and secondary metals, and a second layer of primary metal is electroplated. A further layer of secondary metal can be also electroplated if desired. The process of machining and electroplating can be repeated until the desired structure is formed. Secondary metal is removed by an etchant which does not etch the primary metal.
434 Citations
21 Claims
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1. A method of forming micromechanical structures comprising the steps of:
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(a) providing a plating base on a surface of a substrate; (b) applying a photoresist in a layer onto the plating base; (c) exposing the photoresist in a pattern to radiation to render the photoresist dissolvable in a pattern; (d) removing the dissolvable photoresist; (e) electroplating a first layer of a primary metal onto the plating base in the area from which the photoresist has been removed; (f) removing the remainder of the photoresist; (g) electroplating a first layer of a secondary metal onto the plating base to cover and surround the first layer of the primary metal, the secondary metal chosen so that it can be differentially etched without substantially etching the primary metal; (h) machining the exposed surface of the secondary metal down to a flat surface to a selected height which exposes the first layer of the primary metal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of forming micromechanical structures comprising the steps of:
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(a) providing a plating base on a surface of a substrate; (b) applying a photoresist in a layer onto the plating base; (c) exposing the photoresist in a pattern to radiation to render the photoresist dissolvable in a pattern; (d) removing the dissolvable photoresist; (e) electroplating a first layer of a primary metal onto the plating base in the area from which the photoresist has been removed; (f) removing the remainder of the photoresist; (g) electroplating a first layer of a secondary metal onto the plating base to cover and surround the first layer of the primary metal, the secondary metal chosen so that it can be differentially etched without substantially etching the primary metal; (h) machining the exposed surface of the secondary metal down to a flat surface to a selected height which exposes the first layer of the primary metal; (i) applying a photoresist in a layer over the exposed first layer of primary metal and the first layer of secondary metal; (j) exposing the photoresist to radiation in a pattern to render the photoresist dissolvable in a pattern; (k) removing the dissolvable photoresist; (l) electroplating a second layer of a primary metal in the area from which the photoresist has been removed to cover at least part of the exposed surface of the first layer of primary metal and to also cover part of the exposed surface of the first layer of secondary metal; (m) removing the remainder of the photoresist; (n) electroplating a second layer of a secondary metal over the second layer of the primary metal and over the surface of the first layer of the primary and secondary metals; and
surface to a height which exposes the second layer of the primary metal. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification