Coated Diamond-Turned Replication Master And Associated Process

Abstract

A coated diamond-turned replication master for manufacturing wafer level lens arrays includes a low-hardness diamond-turnable sheet, a mold surface formed in the low-hardness diamond-turnable sheet, and an oxidation-resistant coating formed on the mold surface for protecting same. The mold surface includes a plurality of optical forms, all of which cut therein by a single diamond cutting tool. A process for forming a coated diamond-turned replication master includes a step of forming a mold surface in a low-hardness diamond-turnable sheet using a single diamond cutting tool. The mold surface includes a plurality of optical forms, all of which are formed by the single diamond cutting tool. The process also includes, after the step of forming a plurality of optical forms, coating the mold surface with an oxidation-resistant coating.

What is claimed is: 
     
         1 . A process for forming a coated diamond-turned replication master, comprising the steps of:
 forming a mold surface in a low-hardness diamond-turnable sheet using a single diamond cutting tool, the mold surface comprising a plurality of optical forms, all of which are formed by the single diamond cutting tool; and   coating the mold surface with an oxidation-resistant coating.   
     
     
         2 . The process of  claim 1 , further comprising, before the step of forming the mold surface, forming the sheet of low-hardness diamond turnable material having a thickness between 0.5 mm and 2 mm. 
     
     
         3 . The process of  claim 1 , the step of coating the mold surface comprising forming a layer of the oxidation-resistant coating having a thickness between 0.5 μm and 3 μm. 
     
     
         4 . The process of  claim 1 , the step of forming the mold surface comprising creating a plurality of identical optical forms. 
     
     
         5 . The process of claim  0 , the step of forming the mold surface comprising creating a plurality of optical forms arranged in an evenly-spaced two-dimensional grid. 
     
     
         6 . The process of  claim 5 , the evenly-spaced two-dimensional grid matching a corresponding two-dimensional grid of image sensor die on a CMOS image sensor wafer. 
     
     
         7 . The process of  claim 1 , the step of coating the mold surface comprising one or both of electroplating plating the mold surface and electrolessly plating the mold surface. 
     
     
         8 . The process of  claim 1 , the step of coating the mold surface comprising vacuum-depositing the oxidation-resistant coating. 
     
     
         9 . A coated diamond-turned replication master for manufacturing wafer level lens arrays, comprising:
 a low-hardness diamond-turnable sheet;   a mold surface formed in the low-hardness diamond-turnable sheet, the mold surface comprising a plurality of optical forms, all of which are cut therein by a single diamond cutting tool; and   an oxidation-resistant coating formed on the mold surface for protecting same.   
     
     
         10 . The metal master of  claim 9 , the low-hardness diamond-turnable sheet including a substrate coated with a low-hardness diamond-turnable material. 
     
     
         11 . The metal master of  claim 10 , the substrate being formed of one of steel, aluminum, or Invar. 
     
     
         12 . The metal master of  claim 9 , the low-hardness diamond-turnable sheet being formed of at least one element selected from the group of elements consisting of indium, tin, lead, zinc, magnesium, aluminum, silver, gold, and copper. 
     
     
         13 . The metal master of  claim 9 , the plurality of optical forms having an optical form depth, and the low-hardness diamond-turnable sheet having a thickness exceeding the optical form depth by at least 100 μm. 
     
     
         14 . The metal master of  claim 9 , the oxidation-resistant coating having a thickness between 0.5 μm and 3 μm. 
     
     
         15 . The metal master of  claim 9 , the oxidation-resistant coating being formed of a material that includes one or more of nickel, nickel phosphorus, nickel boron or a copper-nickel alloy. 
     
     
         16 . The metal master of  claim 9 , the oxidation-resistant coating being formed of an amorphous material. 
     
     
         17 . The metal master of  claim 9 , the mold surface comprising a plurality of optical forms arranged in an evenly-spaced two-dimensional grid. 
     
     
         18 . The metal master of  claim 17 , the evenly-spaced two-dimensional grid matching a corresponding two-dimensional grid of image sensor die on a CMOS image sensor wafer. 
     
     
         19 . The metal master of  claim 9 , each of the plurality of optical forms being identical. 
     
     
         20 . The metal master of  claim 9 , each of the plurality of optical forms having a depth that varies as a function of position within the form. 
     
     
         21 . The metal master of  claim 20 , each of the plurality of optical forms having a maximum depth at a non-zero radial distance from the center of the form.