Method for forming micro-lens array and photomask therefor

Abstract

A method for forming a micro-lens array is provided. According to the method, a substrate is provided, and a hard-mask layer is formed. A lithography process is performed on the hard-mask layer by a hard-mask to form a first pattern and a second pattern. Then, the first pattern and the second pattern are reflowed to form a first lens structure and a second lens structure respectively. The photomask includes a first pattern segment and a second pattern segment, and the second pattern segment includes a transparent region and an opaque region. An area of the transparent region of the second pattern segment is larger than 18% of an area of the second pattern segment.

What is claimed is: 
     
         1 . A method for forming a micro-lens array comprising:
 forming a hard-mask layer   performing a lithography process on the hard-mask layer by a photomask to form a first pattern and a second pattern; and   reflowing the first pattern and the second pattern to form a first lens structure and a second lens structure respectively,   wherein the photomask comprises a first pattern segment and a second pattern segment, and the second pattern segment comprises a transparent region and an opaque region, and   wherein an area of the transparent region of the second pattern segment is larger than 18% of an area of the second pattern segment.   
     
     
         2 . The method as claimed in  claim 1 , further comprising:
 forming an under layer, wherein the hard-mask layer is formed on the under layer; and   etching the under layer by using the first lens structure and the second lens structure as an etching mask to form a first micro-lens and a second micro-lens respectively.   
     
     
         3 . The method as claimed in  claim 2 , wherein a height of the first micro-lens is larger than a height of the second micro-lens. 
     
     
         4 . The method as claimed in  claim 2 , further comprising:
 forming a filter layer comprising a first color filter and a second filter,   wherein the under layer is formed on the filter layer, and   wherein the first color filter corresponds to the first micro-lens, and the second color filter corresponds to the second micro-lens.   
     
     
         5 . The method as claimed in  claim 2 , wherein an area of the first micro-lens is larger than an area of the second micro-lens. 
     
     
         6 . The method as claimed in  claim 1 , wherein performing the lithography process on the hard-mask layer by the photomask comprises:
 exposing the hard-mask layer by light through the photomask to form exposed portion and first and second unexposed portions; and   removing the exposed portions from the hard-mask layer;   wherein the first pattern and the second pattern are formed by the first and second unexposed portions respectively   
     
     
         7 . The method as claimed in  claim 1 , further comprising:
 providing a substrate, wherein the hard-mask layer is formed on the substrate;   wherein the substrate comprises a first pixel region, a second pixel region, and a third pixel region, and   wherein the first and second pixel regions correspond to the first pattern segment, and the third pixel region corresponds to the second pattern segment.   
     
     
         8 . The method as claimed in  claim 7 , further comprising:
 forming photo-sensors in the first, second, and third regions of the substrate respectively.   
     
     
         9 . The method as claimed in  claim 1 , wherein a height of the first pattern is larger than a height of the second pattern. 
     
     
         10 . A photomask comprising:
 a first pattern segment; and   a second pattern segment comprising a transparent region and an opaque region,   wherein an area of the transparent region of the second pattern segment is larger than 18% of an area of the second pattern segment.   
     
     
         11 . The photomask as claimed in  claim 10 , wherein the transparent region of the second pattern segment comprises a plurality of openings which are spaced apart from each other, and a total area of the plurality of openings is larger than 18% of the area of the second pattern segment. 
     
     
         12 . The photomask as claimed in  claim 11 , wherein a shape of each of the plurality of openings is triangular or rectangular. 
     
     
         13 . The photomask as claimed in  claim 11 , wherein the second pattern segment comprises a plurality of corners, and the plurality of openings are disposed in the plurality of corners respectively. 
     
     
         14 . The photomask as claimed in  claim 10 , wherein the transparent region of the second pattern segment is on a center area of the second pattern segment, and the transparent region of the second pattern segment comprises a plurality of openings which are spaced apart from each other. 
     
     
         15 . The photomask as claimed in  claim 14 , wherein a shape of each of the plurality of openings is triangular or rectangular. 
     
     
         16 . The photomask as claimed in  claim 10 , wherein a shape of the transparent region of the second pattern segment is square or circular. 
     
     
         17 . The photomask as claimed in  claim 10 , wherein the first pattern segment is an opaque segment. 
     
     
         18 . The photomask as claimed in  claim 10 , wherein an area of the first pattern segment is larger than the area of the second pattern segment. 
     
     
         19 . The photomask as claimed in  claim 10 , wherein an area of the first pattern segment is equal to the area of the second pattern segment. 
     
     
         20 . The photomask as claimed in  claim 10 , wherein the first pattern segment and the second pattern segment are micro-lens pattern segments.