Microlens array substrate

Abstract

A microlens substrate has a tendency to warp when an oxide film is formed and annealed before forming a mask in order to adjust the etching rate of wet etching. A film exerting a stress that cancels out this warping may be formed upon a microlens. This film functions as an optical path length adjusting layer.

What is claimed is: 
     
         1 . A microlens array substrate comprising:
 a substrate;   an oxide film that has an aspheric-surfaced recess is disposed on the substrate, the aspheric-surfaced recess has a tapered edge;   a microlens that has a higher refractive index than the substrate is disposed in the aspheric-surfaced recess, the microlens has a convex surface side and flat surface side opposite the convex surface side; and   an optical path length adjusting layer is disposed on the flat surface side of the microlens,   wherein the substrate is warped in a concave shape by stress from at least one of the oxide film or the microlens,   the optical path length adjusting layer includes a first film and a second film,   the first film receives a compressive stress in a direction orthogonal to a normal direction of the substrate, and   the second film receives a tensile stress in the direction orthogonal to the normal direction of the substrate.   
     
     
         2 . The microlens array substrate according to  claim 1 , wherein the optical path length adjusting layer includes a third film, the third film receiving a compressive stress in a direction orthogonal to a normal direction of the substrate. 
     
     
         3 . The microlens array substrate according to  claim 1 , wherein the substrate is a silica substrate and the oxide film is a silicon oxide film. 
     
     
         4 . The microlens array substrate according to  claim 1 , further comprising:
 a light-blocking film disposed on the optical path length adjusting layer, the light-blocking film receiving a tensile stress in a direction orthogonal to a normal direction of the substrate.   
     
     
         5 . A microlens array substrate comprising:
 a substrate;   an oxide film that has an aspheric-surfaced recess is disposed on the substrate, the aspheric-surfaced recess has a tapered edge;   a microlens that has a higher refractive index than the substrate is disposed in the aspheric-surfaced recess, the microlens has a convex surface side and flat surface side opposite the convex surface side; and   an optical path length adjusting layer is disposed on the flat surface side of the microlens,   wherein the substrate is warped in a concave shape by stress from at least one of the oxide film or the microlens,   the optical path length adjusting layer includes a first film and a second film,   the first film receives a tensile stress in a direction orthogonal to a normal direction of the substrate, and   the second film receives a compressive stress in the direction orthogonal to the normal direction of the substrate.   
     
     
         6 . The microlens array substrate according to  claim 5 , wherein the optical path length adjusting layer includes a third film, the third film receiving a compressive stress in a direction orthogonal to a normal direction of the substrate. 
     
     
         7 . The microlens array substrate according to  claim 5 , wherein the substrate is a silica substrate and the oxide film is a silicon oxide film. 
     
     
         8 . The microlens array substrate according to  claim 5 , further comprising:
 a light-blocking film disposed on the optical path length adjusting layer, the light-blocking film receiving a tensile stress in a direction orthogonal to a normal direction of the substrate.   
     
     
         9 . The electronic device comprising the microlens array substrate according to  claim 1 . 
     
     
         10 . The electronic device comprising the microlens array substrate according to  claim 5 .