Spacer Wafer For Wafer-Level Camera And Method For Manufacturing Same

Abstract

A spacer wafer for a wafer-level camera, a wafer-level camera including the spacer wafer and a method of manufacturing a spacer wafer include a layer of photoresist being formed over a substrate, the layer of photoresist being exposed to radiation through a mask that defines a spacer geometry for at least one wafer-level camera element. The layer photoresist is developed, such that the layer of photoresist is the spacer wafer for the wafer-level camera.

1 . A method of manufacturing a spacer wafer for a wafer-level camera, comprising:
 forming a layer of photoresist over a substrate;   exposing the layer of photoresist to radiation through a mask that defines a spacer geometry for at least one wafer-level camera element; and   developing the layer of photoresist, such that the layer of photoresist is the spacer wafer for the wafer-level camera.   
     
     
         2 . The method of  claim 1 , further comprising:
 forming a sacrificial layer on the substrate before forming the layer of photoresist over the substrate; and   after developing the layer of photoresist, removing the sacrificial layer, such that the layer of photoresist is a standalone spacer.   
     
     
         3 . The method of  claim 2 , wherein the sacrificial layer comprises polystyrene. 
     
     
         4 . The method of  claim 2 , wherein the sacrificial layer comprises wax. 
     
     
         5 . The method of  claim 1 , wherein the photoresist is negative photoresist. 
     
     
         6 . The method of  claim 1 , wherein the photoresist is epoxy-based photoresist. 
     
     
         7 . The method of  claim 1 , wherein the photoresist is SU-8 photoresist. 
     
     
         8 . The method of  claim 1 , wherein a thickness of the spacer wafer is less than 300 μm. 
     
     
         9 . The method of  claim 1 , further comprising machining the layer of photoresist to a desired thickness. 
     
     
         10 . The method of  claim 9 , wherein the layer of photoresist is machined to a thickness less than 300 μm. 
     
     
         11 . The method of  claim 1 , further comprising machining the layer of photoresist to a plurality of thicknesses. 
     
     
         12 . The method of  claim 1 , further comprising aligning a mask over the layer of photoresist before exposing the layer of photoresist. 
     
     
         13 . The method of  claim 12 , wherein the mask defines at least one hole to be formed in the layer of photoresist. 
     
     
         14 . The method of  claim 13 , wherein the hole to be formed in the layer of photoresist is tapered. 
     
     
         15 . The method of  claim 1 , further comprising forming at least one element in the substrate before forming the layer of photoresist. 
     
     
         16 . The method of  claim 15 , wherein the at least one element comprises one of a lens and a fiducial marking. 
     
     
         17 . The method of  claim 1 , wherein the substrate is formed of glass. 
     
     
         18 . The method of  claim 1 , further comprising forming an adhesion promoter over the substrate before forming the layer of photoresist over the substrate. 
     
     
         19 . The method of  claim 1 , wherein:
 the layer of photoresist is formed over a first surface of the substrate; and   the method further comprises forming a second layer of photoresist over a second surface of the substrate, such that first and second spacer wafers are formed over the first and second surfaces, respectively, of the substrate.   
     
     
         20 . A wafer-level camera, comprising:
 an element layer on which at least one element is formed; and   a spacer wafer over the element layer, the spacer wafer being formed of a layer of photoresist and defining a spacer geometry for the at least one element.   
     
     
         21 . The wafer-level camera of  claim 20 , wherein the photoresist is negative photoresist. 
     
     
         22 . The wafer-level camera of  claim 20 , wherein the photoresist is epoxy-based photoresist. 
     
     
         23 . The wafer-level camera of  claim 20 , wherein the photoresist is SU-8 photoresist. 
     
     
         24 . The wafer-level camera of  claim 20 , wherein a thickness of the spacer wafer is less than 300 μm. 
     
     
         25 . The wafer-level camera of  claim 20 , wherein the spacer wafer has a plurality of thicknesses. 
     
     
         26 . The wafer-level camera of  claim 20 , wherein the at least one element comprises a lens. 
     
     
         27 . The wafer-level camera of  claim 20 , wherein the element layer is formed of glass. 
     
     
         28 . The wafer-level camera of  claim 20 , wherein the spacer wafer comprises at least one hole. 
     
     
         29 . The wafer-level camera of  claim 28 , wherein the hole is tapered. 
     
     
         30 . The wafer-level camera of  claim 20 , wherein the spacer wafer is formed over a first surface of the element layer, and further comprising a second spacer wafer formed over a second surface of the element layer, such that first and second spacer wafers are formed over the first and second surfaces, respectively, of the element layer. 
     
     
         31 . The wafer-level camera of  claim 20 , wherein a thickness of the spacer wafer defines a spacing between the at least one element and a second element of the wafer-level camera. 
     
     
         32 . The wafer-level camera of  claim 31 , wherein at least one of the first and second elements is at least one of a lens and a sensor. 
     
     
         33 . A spacer wafer for a wafer-level camera, comprising:
 a layer of photoresist; and   a pattern formed on the layer of photoresist, the pattern defining a spacer geometry for at least one element of the wafer-level camera.   
     
     
         34 . The spacer wafer of  claim 33 , wherein a thickness of the spacer wafer defines a spacing between the at least one element and a second element of the wafer-level camera. 
     
     
         35 . The spacer wafer of  claim 34 , wherein at least one of the first and second elements is at least one of a lens and a sensor.