Microstructure array, and methods of fabricating a microstructure array, a mold for forming a microstructure array, and a microlens array

Abstract

In a method for fabricating an array of microstructures, a substrate with an electrically-conductive portion is provided, an insulating mask layer is formed on the electrically-conductive portion of the substrate, a plurality of openings are formed in the insulating mask layer to expose the electrically-conductive portion, and a first plated or electrodeposited layer is deposited in the openings and on the insulating mask layer by electro- or electroless-plating, or electrodeposition. At least a surface of the first plated or electrodeposited layer is made electrically conductive. After that, the insulating mask layer is removed, and a second plated layer is formed on the first plated or electrodeposited layer and on the electrically-conductive portion by electroplating to firmly fix the first plated or electrodeposited layer to the substrate.

What is claimed is:  
     
         1 . A method for fabricating an array of microstructures comprising the steps of: 
 preparing a substrate with an electrically-conductive portion;    forming an insulating mask layer on the electrically-conductive portion;    forming a plurality of openings in the insulating mask layer to expose the electrically-conductive portion;    forming a first plated or electrodeposited layer in the openings and on the insulating mask layer by electro- or electroless-plating, or electrodeposition, with at least a surface of the first plated or electrodeposited layer being electrically conductive;    removing the insulating mask layer; and    forming a second plated layer on the first plated or electrodeposited layer and on the electrically-conductive portion by electroplating.    
     
     
         2 . A fabrication method according to  claim 1 , wherein the step of forming the first plated or electrodeposited layer is stopped after a thickness of the first plated or electrodeposited layer reaches half a designed final height or more of the second plated layer above a central portion of the opening.  
     
     
         3 . A fabrication method according to  claim 1 , wherein the first plated or electrodeposited layers are formed in the step of forming the first plated or electrodeposited layer such that the insulating mask layer between the adjacent first plated or electrodeposited layers is not completely covered.  
     
     
         4 . A fabrication method according to  claim 1 , wherein the step of forming the second plated layer is stopped after a thickness of the second plated layer reaches a thickness of the insulating mask layer or more.  
     
     
         5 . A fabrication method according to  claim 1 , wherein the opening has a circular shape and the microstructure is a semispherical microstructure.  
     
     
         6 . A fabrication method according to  claim 1 , wherein the opening has an elongated stripe shape and the microstructure is a semicylindrical microstructure.  
     
     
         7 . A fabrication method according to  claim 1 , further comprising a step of forming a mold on the substrate with the first plated or electrodeposited layer and the second plated layer; and a step of separating the mold from the substrate.  
     
     
         8 . A fabrication method according to  claim 7 , wherein the mold is formed using electroplating.  
     
     
         9 . A fabrication method according to  claim 7 , wherein the mold is a mold for fabricating a microlens array.  
     
     
         10 . A fabrication method according to  claim 9 , further comprising a step of coating a light-transmitting material on the mold; a step of hardening the light-transmitting material; and a step of separating the material from the mold to obtain the microlens array.  
     
     
         11 . A microstructure array comprising: 
 a substrate having an electrically-conductive portion;    a first plated or electrodeposited layer formed on the electrically-conductive portion by electro- or electroless-plating or electrodeposition using a plurality of openings formed in an insulating mask layer formed on the electrically-conductive portion of the substrate to expose the electrically-conductive portion, at least a surface of the first plated or electrodeposited layer being electrically conductive, and the insulating mask layer being finally removed; and    a second plated layer formed on the first plated or electrodeposited layer and on the electrically-conductive portion by electroplating.    
     
     
         12 . A microstructure array according to  claim 11 , wherein a height of the second plated layer formed on the first plated or electrodeposited layer above a central portion of the opening is in a range from 1 μm to 100 μm.  
     
     
         13 . A microstructure array according to  claim 11 , wherein a thickness of the second plated layer formed on the first plated or electrodeposited layer above a central portion of the opening is equal to or smaller than a thickness of the first plated or electrodeposited layer above the central portion of the opening.  
     
     
         14 . A microstructure array according to  claim 11 , wherein the first plated or electrodeposited layers are formed so as not to completely cover the electrically-conductive portion.  
     
     
         15 . A microstructure array according to  claim 11 , wherein a thickness of the second plated layer is equal to or larger than a spacing between the first plated layer and the electrically-conductive portion.  
     
     
         16 . A microstructure array according to  claim 11 , wherein the opening has a circular shape and the microstructure is a semispherical microstructure.  
     
     
         17 . A microstructure array according to  claim 11 , wherein the opening has an elongated stripe shape and the microstructure is a semicylindrical microstructure.