Epoxy removal process for microformed electroplated devices

Abstract

The present invention is directed to a method of removing epoxy-based photoresist from a manufactured metallic microstructure or deep etched via, comprising the steps of (1) providing a form comprising an epoxy-based photoresist and a manufactured metallic microstructure; (2) optionally exposing the form to a solvent, aqueous alkali, or amine-based photoresist stripper; (3) exposing the form to an alkali permanganate oxidizing solution to remove the form from the manufactured metallic microstructure, the alkali permanganate oxidizing solution comprising from about 4% to about 9% permanganate by weight, based on the total weight of the alkali permanganate solution, and from about 3% to about 6% alkali by weight, based on the total weight of the alkali permanganate solution; and (4) exposing the manufactured metallic microstructure to a neutralizing solution comprising from about 5% to about 10% by weight of an acid and from about 1% to about 10% by weight of a reducing agent, all weight percents being based on the total weight of the neutralizing solution.

1 . A method of removing epoxy-based photoresist from a manufactured metallic microstructure, comprising the steps of
 (1) providing a form comprising an epoxy-based photoresist and a manufactured metallic microstructure;   (2) optionally exposing said form to a solvent, aqueous alkali, or amine-based photoresist stripper;   (3) exposing said form to an alkali permanganate oxidizing solution to remove said form from said manufactured metallic microstructure, said alkali permanganate oxidizing solution comprising from about 4% to about 9% permanganate by weight, based on the total weight of said alkali permanganate solution, and from about 3% to about 6% alkali by weight, based on the total weight of said alkali permanganate solution; and   (4) exposing said manufactured metallic microstructure to a neutralizing solution comprising from about 5% to about 10% by weight of an acid and from about 1% to about 10% by weight of a reducing agent, all weight percents being based on the total weight of said neutralizing solution.   
   
   
       2 . The method of  claim 1 , wherein said epoxy-based photoresist is a crosslinked carboxylated epoxy cresol novolak photoresist. 
   
   
       3 . The method of  claim 1 , wherein said alkali permanganate oxidizing solution comprises about 5% permanganate by weight and about 5% alkali by weight, all based on the total weight of said alkali permanganate solution. 
   
   
       4 . The method of  claim 1 , wherein said reducing agent is selected from the group consisting of hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine phosphate, and combinations thereof. 
   
   
       5 . The method of  claim 1 , wherein said acid is selected from the group consisting of sulfuric acid, sulfamic acid, methane sulfonic acid, and combinations thereof. 
   
   
       6 . The method of  claim 1 , wherein said solvent or amine-based photoresist stripper is selected from the group consisting of NMP, dimethylsulfoxide (DMSO), sulfolane, dimethylforamide (DMF), dimethylacetamide (DMAC), diethylene glycol monobutyl ether, propylene carbonate, and combinations thereof. 
   
   
       7 . The method of  claim 1 , wherein said manufactured metallic microstructure is a micromachined part. 
   
   
       8 . The method of  claim 1 , wherein said manufactured metallic microstructure is a metal bump. 
   
   
       9 . A method of manufacturing a MEMS device, comprising the steps of:
 (1) providing a form comprising an epoxy-based photoresist and a manufactured MEMS device;   (2) optionally exposing said form to a solvent, aqueous alkali, or amine-based photoresist stripper;   (3) exposing said form to an alkali permanganate oxidizing solution to remove said form from said manufactured MEMS device, said alkali permanganate oxidizing solution comprising from about 4% to about 9% permanganate by weight, based on the total weight of said alkali permanganate solution, and from about 3% to about 6% alkali by weight, based on the total weight of said alkali permanganate solution; and   (4) exposing said manufactured MEMS device to a neutralizing solution comprising from about 5% to about 10% by weight of an acid and from about 1% to about 10% by weight of a reducing agent, all weight percents being based on the total weight of said neutralizing solution.   
   
   
       10 . The method of  claim 9 , wherein said epoxy-based photoresist is a crosslinked carboxylated epoxy cresol novolak photoresist. 
   
   
       11 . The method of  claim 9 , wherein said alkali permanganate oxidizing solution comprises about 5% permanganate by weight and about 5% alkali by weight, all based on the total weight of said alkali permanganate solution. 
   
   
       12 . The method of  claim 9 , wherein said reducing agent is selected from the group consisting of hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine phosphate, and combinations thereof. 
   
   
       13 . The method of  claim 9 , wherein said acid is selected from the group consisting of sulfuric acid, sulfamic acid, methane sulfonic acid, and combinations thereof. 
   
   
       14 . The method of  claim 9 , wherein said solvent or amine-based photoresist stripper is selected from the group consisting of NMP, dimethylsulfoxide (DMSO), sulfolane, dimethylforamide (DMF), dimethylacetamide (DMAC), diethylene glycol monobutyl ether, propylene carbonate, and combinations thereof. 
   
   
       15 . A method of removing crosslinked epoxy novolak photoresist from a substrate, comprising the steps of:
 (1) providing a substrate comprising a form made from crosslinked epoxy novolak photoresist;   (2) optionally exposing said substrate to a solvent, aqueous alkali, or amine-based photoresist stripper;   (3) exposing said substrate to an alkali permanganate oxidizing solution to remove said crosslinked epoxy novolak photoresist from said substrate, said alkali permanganate oxidizing solution comprising from about 4% to about 9% permanganate by weight, based on the total weight of said alkali permanganate solution, and from about 3% to about 6% alkali by weight, based on the total weight of said alkali permanganate solution; and   (4) exposing said substrate to a neutralizing solution comprising from about 5% to about 10% by weight of an acid and from about 1% to about 10% by weight of a reducing agent, all weight percents being based on the total weight of said neutralizing solution.   
   
   
       16 . The method of  claim 15 , wherein said alkali permanganate oxidizing solution comprises about 5% permanganate by weight and about 5% alkali by weight, all based on the total weight of said alkali permanganate solution. 
   
   
       17 . The method of  claim 15 , wherein said reducing agent is selected from the group consisting of hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine phosphate, and combinations thereof. 
   
   
       18 . The method of  claim 15 , wherein said acid is selected from the group consisting of sulfuric acid, sulfamic acid, methane sulfonic acid, and combinations thereof. 
   
   
       19 . The method of  claim 15 , wherein said solvent or amine-based photoresist stripper is selected from the group consisting of NMP, dimethylsulfoxide (DMSO), sulfolane, dimethylforamide (DMF), dimethylacetamide (DMAC), diethylene glycol monobutyl ether, propylene carbonate, and combinations thereof. 
   
   
       20 . The method of  claim 15 , wherein said epoxy novolak photoresist is SU-8. 
   
   
       21 . A method of removing crosslinked epoxy-based photoresist, comprising the steps of:
 (1) lithographically producing an etch mask on a substrate with an epoxy-based photoresist;   (2) exposing said substrate to a DRIE plasma comprising alternating gases of sulfur hexafluoride and octafluorocyclobutane;   (3) exposing said substrate to an alkali permanganate oxidizing solution to remove said crosslinked epoxy novolak photoresist from said substrate, said alkali permanganate oxidizing solution comprising from about 4% to about 9% permanganate by weight, based on the total weight of said alkali permanganate solution, and from about 3% to about 6% alkali by weight, based on the total weight of said alkali permanganate solution; and   (4) exposing said substrate to a neutralizing solution comprising from about 5% to about 10% by weight of an acid and from about 1% to about 10% by weight of a reducing agent, all weight percents being based on the total weight of said neutralizing solution.   
   
   
       22 . The method of  claim 21 , wherein said alkali permanganate oxidizing solution comprises about 5% permanganate by weight and about 5% alkali by weight, all based on the total weight of said alkali permanganate solution. 
   
   
       23 . The method of  claim 21 , wherein said reducing agent is selected from the group consisting of hydroxylamine sulfate, hydroxylamine nitrate, hydroxylamine phosphate, and combinations thereof. 
   
   
       24 . The method of  claim 21 , wherein said acid is selected from the group consisting of sulfuric acid, sulfamic acid, methane sulfonic acid, and combinations thereof.