EP0607680A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Formation of microstructures using a preformed photoresist sheet
Assignee: Wisconsin Alumni Research Foundation
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Filing: 1993-12-15
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Granted: —
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Expires: 2013-12-15
Abstract
Abstract In the formation of microstructures, a preformed sheet of photoresist, such as polymethylmethacrylate (PMMA), which is strain free, may be milled down before or after adherence to a substrate to a desired thickness. The photoresist is patterned by exposure through a mask to radiation, such as X-rays, and developed using a developer to remove the photoresist material which has been rendered susceptible to the developer. Micrometal structures may be formed by electroplating metal into the areas from which the photoresist has been removed. The photoresist itself may form useful microstructures, and can be removed from the substrate by utilizing a release layer between the substrate and the preformed sheet which can be removed by a remover which does not affect the photoresist. Multiple layers of patterned photoresist can be built up to allow complex three dimensional microstructures to be formed.
Inventors
- 👤 Henry Guckel
- 👤 Todd R. Christenson
- 👤 Kenneth Skrobis
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 06:50
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/20; G03F7/2037; G03F7/2039; G03F7/26; G03F7/38; B; B81; B81C; B81C1/00; B81C1/00349; B81C1/0038; G03F7/0035; H; H10; H10P; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; B81C2201/00; B81C2201/01; B81C2201/0101; B81C2201/0128; B81C2201/0156; B81C2201/0159; B81C2201/0174; B81C2201/019; B81C2201/03; B81C2201/032; Y; Y10; Y10S; Y10S430/00; Y10S430/167; Y10S430/168; Y10T; Y10T428/00; Y10T428/31504
Claims Analysis
Total Claims: 47
Claim 1
Independent Claim
86 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the photoresist sheet in a pattern to radiation which will change its susceptibility to a developer; (c) mechanically removing the material of the photoresist sheet to reduce the thickness of the sheet to a desired thickness; and (d) applying a developer to the exposed photoresist to remove photoresist which is susceptible to the developer.
Claim 2
Independent Claim
86 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the photoresist sheet in a pattern to radiation which will change its susceptibility to a developer; (c) mechanically removing the material of the photoresist sheet to reduce the thickness of the sheet to a desired thickness; and (d) applying a developer to the exposed photoresist to remove photoresist which is susceptible to the developer.
Claim 3
Dependent Claim
13 words
The method of claim 1, wherein the material of the photoresist is PMMA.
Claim 4
Dependent Claim
19 words
The method of claim 2, wherein the PMMA of the photoresist is a very high molecular weight linear PMMA.
Claim 5
Dependent Claim
27 words
The method of claim 3, wherein the step of exposing the photoresist in a pattern is carried out by exposing the photoresist to X-rays from a synchrotron.
Claim 6
Dependent Claim
64 words
The method of claim 1, 2 or 3, including the initial steps of applying a sacrificial layer to a substrate and adhering the preformed sheet to the sacrificial layer, then after all of the steps of claim 1, the additional step of removing the sacrificial layer with a remover which does not affect the photoresist material to free the remaining photoresist from the substrate.
Claim 7
Dependent Claim
23 words
The method of claim 5, wherein the sacrificial layer is a material selected from the group consisting of titanium and partially imidized polyimide.
Claim 8
Independent Claim
193 words
A method of forming microstructures comprising the steps of: (a) providing a first preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the photoresist sheet to radiation in a pattern which will change its susceptibility to a developer; (c) mechanically removing the material of the photoresist sheet to reduce the thickness of the sheet to a desired thickness constituting the first layer of photoresist; (d) providing a second preformed sheet of photoresist material which may be exposed to radiation to affect its susceptibility to a developer; (e) adhering the second photoresist sheet to the first layer of photoresist to form a laminate; (f) mechanically removing the material of the second photoresist sheet to reduce the thickness of the sheet to a desired thickness constituting a second layer of photoresist; (g) exposing the first and second layers of the photoresist to a pattern of radiation which will change the susceptibility of the photoresist of the second layer to a developer; and (h) removing the photoresist in the first and second layers which is susceptible to a developer using a developer for the photoresist.
Claim 9
Independent Claim
193 words
A method of forming microstructures comprising the steps of: (a) providing a first preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the photoresist sheet to radiation in a pattern which will change its susceptibility to a developer; (c) mechanically removing the material of the photoresist sheet to reduce the thickness of the sheet to a desired thickness constituting the first layer of photoresist; (d) providing a second preformed sheet of photoresist material which may be exposed to radiation to affect its susceptibility to a developer; (e) adhering the second photoresist sheet to the first layer of photoresist to form a laminate; (f) mechanically removing the material of the second photoresist sheet to reduce the thickness of the sheet to a desired thickness constituting a second layer of photoresist; (g) exposing the first and second layers of the photoresist to a pattern of radiation which will change the susceptibility of the photoresist of the second layer to a developer; and (h) removing the photoresist in the first and second layers which is susceptible to a developer using a developer for the photoresist.
Claim 10
Dependent Claim
126 words
The method of claim 7, including the additional steps of providing a third preformed sheet of photoresist material which can be exposed to radiation to change its susceptibility to a developer; adhering the third photoresist sheet to the second layer of the laminate; mechanically removing the material of the third photoresist sheet adhered to the second layer to reduce the thickness of the sheet to a desired thickness comprising a third layer of the laminate; exposing the third layer of photoresist in a pattern to radiation which will change the susceptibility of the photoresist to a developer, and then carrying out the step of removing the photoresist susceptible to a developer in each of the first, second and third layers utilising a developer for the photoresist.
Claim 11
Dependent Claim
44 words
The method of claim 7 or 8, wherein the step of removing the photoresist susceptible to a developer in the first and second layers is carried out before the second photoresist sheet constituting the second layer is adhered to the first layer of photoresist.
Claim 12
Independent Claim
107 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the first photoresist sheet to radiation in a pattern which will result in susceptibility of the photoresist to a developer partially but not entirely through the thickness of the photoresist sheet; and (c) applying a developer to the exposed photoresist sheet to remove photoresist which is susceptible to the developer to leave a pattern of voids in the exposed side of the photoresist sheet which voids extend partially but not entirely through the photoresist sheet.
Claim 13
Independent Claim
107 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the first photoresist sheet to radiation in a pattern which will result in susceptibility of the photoresist to a developer partially but not entirely through the thickness of the photoresist sheet; and (c) applying a developer to the exposed photoresist sheet to remove photoresist which is susceptible to the developer to leave a pattern of voids in the exposed side of the photoresist sheet which voids extend partially but not entirely through the photoresist sheet.
Claim 14
Dependent Claim
33 words
The method of claim 10, including the additional steps of adhering the first photoresist sheet on the side which has the voids formed therein to a layer of material to form a laminate.
Claim 15
Dependent Claim
84 words
The method of claim 11, wherein the layer of material is a photoresist and including, before the step of adhering the first preformed sheet to the layer of material, the additional steps of exposing the photoresist layer to radiation in a pattern which will affect its susceptibility to a developer, applying a developer to the exposed layer photoresist to remove photoresist which is susceptible to the developer, and then carrying out the step of adhering the first preformed sheet of photoresist to the layer.
Claim 16
Dependent Claim
57 words
The method of claim 11, including, after the step of adhering the first preformed sheet of photoresist to a layer of material, the additional step of mechanically removing the material of the first preformed photoresist sheet to reduce the thickness of the sheet to fully expose the voids which have been formed in the first preformed sheet.
Claim 17
Dependent Claim
140 words
The method of claim 13, including, after the step of mechanically removing the material of the first preformed sheet, the additional steps of providing a second preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer, exposing the second photoresist sheet to radiation in a pattern which will change the susceptibility of the photoresist to a developer partially but not entirely through the thickness of the second photoresist sheets, applying a developer to the exposed second photoresist sheet to remove the photoresist which is susceptible to the developer to leave voids in one side of the second photoresist sheet which extend partially but not entirely through the thickness of the sheet, and then adhering the second photoresist sheet by the side having voids therein to the surface of the first photoresist sheet.
Claim 18
Dependent Claim
50 words
The method of claim 15, including the additional step, after the second photoresist sheet has been adhered to the first photoresist sheet, of mechanically removing the material of the second photoresist sheet to reduce the thickness of the sheet to fully expose the voids formed in the second photoresist sheet.
Claim 19
Independent Claim
172 words
A method of forming microstructures comprising the steps of: (a) providing a first preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the first photoresist sheet to radiation in a pattern which will result in susceptibility of the photoresist to a developer partially but not entirely through the thickness of the photoresist sheet; (c) adhering the first photoresist sheet on the side which has photoresist which is susceptible to a developer to a layer of photoresist which has a pattern of areas therein which are susceptible to the developer, to form a laminate; (d) mechanically removing the material of the first preformed photoresist sheet to reduce the thickness of the sheet to expose the areas of the first preformed sheet which are susceptible to removal by the developer; and (e) applying a developer to the laminate to remove photoresist which is susceptible to the developer to leave a pattern of voids in the first photoresist sheet and the underlying photoresist layer.
Claim 20
Independent Claim
172 words
A method of forming microstructures comprising the steps of: (a) providing a first preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer; (b) exposing the first photoresist sheet to radiation in a pattern which will result in susceptibility of the photoresist to a developer partially but not entirely through the thickness of the photoresist sheet; (c) adhering the first photoresist sheet on the side which has photoresist which is susceptible to a developer to a layer of photoresist which has a pattern of areas therein which are susceptible to the developer, to form a laminate; (d) mechanically removing the material of the first preformed photoresist sheet to reduce the thickness of the sheet to expose the areas of the first preformed sheet which are susceptible to removal by the developer; and (e) applying a developer to the laminate to remove photoresist which is susceptible to the developer to leave a pattern of voids in the first photoresist sheet and the underlying photoresist layer.
Claim 21
Dependent Claim
114 words
The method of claim 16, including, before the step of adhering the first photoresist sheet to the photoresist layer, the additional steps of providing the photoresist layer from a preformed sheet of photoresist material which can be exposed to radiation to affect its susceptibility to a developer partially but not entirely through the thickness of the photoresist sheet, mechanically removing the material of the photoresist sheet from the side opposite the exposed side of the sheet to reduce the thickness of the sheet to fully expose the areas of the sheet which are susceptible to the layer to provide the photoresist layer, and thereafter adhering the first preformed photoresist sheet to the photoresist layer.
Claim 22
Dependent Claim
57 words
The method of claim 17, including before the step of mechanically removing the material of the preformed photoresist sheet from which the photoresist layer is formed, the step of adhering the exposed side of that preformed photoresist sheet to a substrate, and then carrying out the step of mechanically removing the material of the preformed photoresist sheet.
Claim 23
Independent Claim
82 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheetof PMMApho- toresist material; (b) exposing the first photoresist sheet in a pattern to X-rays to render exposed areas of the photoresist sheet susceptible to a developer; (c) mechanically removing the material of the first photoresist sheet to reduce the thickness of the sheet to a desired thickness; and (d) applying a developer to the first photoresist sheet to remove the exposed photoresist which is susceptible to the developer.
Claim 24
Independent Claim
82 words
A method of forming microstructures comprising the steps of: (a) providing a preformed sheetof PMMApho- toresist material; (b) exposing the first photoresist sheet in a pattern to X-rays to render exposed areas of the photoresist sheet susceptible to a developer; (c) mechanically removing the material of the first photoresist sheet to reduce the thickness of the sheet to a desired thickness; and (d) applying a developer to the first photoresist sheet to remove the exposed photoresist which is susceptible to the developer.
Claim 25
Dependent Claim
48 words
The method of claim 1 or 19, wherein the material of the first photoresist sheet is very high molecular weight linear PMMA, and wherein the step of removing the remaining photoresist is carried out by exposing the photoresist to a bath of a solvent which dissolves the PMMA.
Claim 26
Dependent Claim
18 words
The method of claim 20, wherein the solvent which is used to dissolve the PMMA is methylene chloride.
Claim 27
Dependent Claim
80 words
The method of claim 1 or 21, including the steps of spinning on a thin initial layer of non-cross- linked PMMA onto the surface of a substrate and solidifying the initial layer of PMMA, applying the first preformed sheet of PMMA to the initial layer, and applying a liquid methyl methacrylate monomer to the interface between the preformed sheet and the initial layer to provide adhesion between the preformed sheet and the initial layer at the interface between the two.
Claim 28
Independent Claim
43 words
The method of any preceding claim,wherein the first preformed sheet of photoresist is at least 1 mm thick, and in the step of mechanically removing the material of the photoresist sheet, the thickness of the sheet is reduced to less than 1 mm.
Claim 29
Dependent Claim
99 words
The method of claim 19, further comprising the steps of: (a) providing a second preformed sheet of PMMA photoresist material; (b) adhering the second photoresist sheet to the first photoresist sheet to form a laminate; (c) mechanically removing the material of the second photoresist sheet to reduce the thickness of the sheet to a desired thickness; (d) exposing the second photoresist sheet to a pattern of X-rays which will render the exposed areas of the second photoresist sheet susceptible to a developer; and (e) removing the exposed photoresist in the second photoresist sheet using a developer for the photoresist.
Claim 30
Dependent Claim
44 words
The method of claim 7 or 24, including the step of adhering the first preformed photoresist sheet to a substrate before the steps of exposing the first photoresist sheet to a pattern of radiation and mechanically removing the material of the first photoresist sheet.
Claim 31
Dependent Claim
94 words
The method of claim 1, 19 or 25, wherein the step of adhering the first sheet of photoresist to the substrate includes the step of applying a thin layer of metal to the substrate as a plating base and adhering the preformed sheet of the photoresist to the plating base, then after all of the steps of claim 1, 19 or 25, the additional steps of electro- plating metal in the areas in which the photoresist has been removed, and then removing the remaining photoresist to leave the electroplated metal structures on the substrate.
Claim 32
Dependent Claim
38 words
The method of claim 25, wherein the step of removing the exposed photoresist with a developer in the first and second photoresist sheets is carried out before the second photoresist sheet is adhered to the first photoresist sheet.
Claim 33
Dependent Claim
42 words
The method of claim 25, wherein the step of adhering the second photoresist sheet to the first photoresist sheet is carried out after the steps of exposing the second photoresist sheet to a pattern of X-rays and of removing the exposed photoresist.
Claim 34
Dependent Claim
34 words
The method of claim 25, wherein the step of adhering the second photoresist sheet to the first photoresist sheet is carried out before the step of applying a developer to the first photoresist sheet.
Claim 35
Dependent Claim
27 words
The method of claim 25, wherein the second photoresist sheet is adhered to the first photoresist sheet by wetting the interface between the sheets with methyl methacrylate.
Claim 36
Dependent Claim
63 words
A laminate including micromechanical structures therein comprising: two preformed sheets of photoresist material adhered together at one of the sides of each sheet, the side of each sheet of photoresist which is adhered to the other sheet having a pattern of voids therein which extend partially but not entirely through the sheet, each sheet of photoresist being about 3 mm thick or less.
Claim 37
Dependent Claim
63 words
A laminate including micromechanical structures therein comprising: two preformed sheets of photoresist material adhered together at one of the sides of each sheet, the side of each sheet of photoresist which is adhered to the other sheet having a pattern of voids therein which extend partially but not entirely through the sheet, each sheet of photoresist being about 3 mm thick or less.
Claim 38
Dependent Claim
22 words
The laminate of claim 31, further including a substrate having a surface to which one of the two photoresist sheets is adhered.
Claim 39
Dependent Claim
14 words
The laminate of claim 32, wherein the material of the photoresist sheets is PMMA.
Claim 40
Dependent Claim
76 words
A micromechanical structure comprising: a free body of PMMA having a top surface and a bottom surface, at least one of the top and bottom surfaces being mechanically milled, the thickness of the body between the top and bottom surfaces being less than about 1 mm, the body formed of preformed PMMA with substantially no internal strain therein, and sidewalls for the body which are substantially perpendicular to the top and bottom surfaces of the body.
Claim 41
Dependent Claim
76 words
A micromechanical structure comprising: a free body of PMMA having a top surface and a bottom surface, at least one of the top and bottom surfaces being mechanically milled, the thickness of the body between the top and bottom surfaces being less than about 1 mm, the body formed of preformed PMMA with substantially no internal strain therein, and sidewalls for the body which are substantially perpendicular to the top and bottom surfaces of the body.
Claim 42
Dependent Claim
46 words
A laminated structure comprising: a substrate having a surface; a thin layer of low molecular weight PMMA on the surface of the substrate; and a preformed sheet of PMMA less than about 3 mm thick which is solvent-bonded to the layer of low molecular weight PMMA.
Claim 43
Dependent Claim
46 words
A laminated structure comprising: a substrate having a surface; a thin layer of low molecular weight PMMA on the surface of the substrate; and a preformed sheet of PMMA less than about 3 mm thick which is solvent-bonded to the layer of low molecular weight PMMA.
Claim 44
Dependent Claim
20 words
The laminated structure of claim 35, wherein the layer of low molecular weight PMMA is less than 5 µm thick.
Claim 45
Dependent Claim
24 words
The laminated structure of claim 35 or 36, wherein the low molecular weight layer has a molecular weight in the range of 496 K.
Claim 46
Independent Claim
62 words
A method of forming a laminated structure comprising the steps of: spinning a thin layer of low molecular weight PMMAonto a substrate and curing the layer; wetting the layer of low molecular weight PMMA with MMA monomer; and applying a preformed sheet of PMMA to the wetted layer to adhere the preformed sheet to the wetted layer and thus to the substrate.
Claim 47
Independent Claim
62 words
A method of forming a laminated structure comprising the steps of: spinning a thin layer of low molecular weight PMMAonto a substrate and curing the layer; wetting the layer of low molecular weight PMMA with MMA monomer; and applying a preformed sheet of PMMA to the wetted layer to adhere the preformed sheet to the wetted layer and thus to the substrate.
References Cited (Backward Citations)
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