Method of making fine-pitch circuit lines

Abstract

A method of making fine-pitch circuit lines includes steps of preparing an insulative substrate, disposing a conductive metal layer on the insulative substrate, disposing on a whole or a part of a top surface of the conductive metal layer a hetero layer having an etching rate smaller than that of the conductive metal layer, forming a patterned mask of circuit lines on the hetero layer, wet etching the hetero layer and the conductive metal layer, and removing the patterned mask and the hetero layer so as to form fin-pitch circuit lines having a high etching factor on the insulative substrate.

1 . A method of making fine-pitch circuit lines, comprising the steps of:
 preparing an insulative substrate;   disposing a conductive metal layer on the insulative substrate;   disposing on a whole or a part of a top surface of the conductive metal layer a hetero layer having an etching rate smaller than that of the conductive metal layer;   forming a patterned mask of circuit lines on the hetero layer;   etching the hetero layer and the conductive metal layer with a liquid etchant, and   removing the patterned mask and the hetero layer.   
     
     
         2 . The method as claimed in  claim 1 , wherein the conductive metal layer comprises one selected from the group consisting of copper and a copper alloy. 
     
     
         3 . The method as claimed in  claim 2 , wherein the hetero layer comprises nickel. 
     
     
         4 . The method as claimed in  claim 2 , wherein the hetero layer comprises tin. 
     
     
         5 . The method as claimed in  claim 1 , wherein the hetero layer has a thickness smaller than that of the conductive metal layer. 
     
     
         6 . The method as claimed in  claim 3 , wherein the hetero layer is disposed on the conductive metal layer by the process selected from the group consisting of electroplating, chemical vapor deposition and sputtering. 
     
     
         7 . The method as claimed in  claim 3 , wherein the liquid etchant is FeCl 3 . 
     
     
         8 . A method of making fine-pitch circuit lines, comprising the steps of:
 preparing an insulative substrate;   preparing a laminate comprising a conductive metal layer and a hetero layer disposed on the conductive metal layer and having an etching rate smaller than that of the conductive metal layer, and disposing the laminate on the insulative substrate in a way that the conductive metal layer is bonded on the insulative substrate;   forming a patterned mask of circuit lines on the hetero layer of the laminate;   etching the hetero layer and the conductive metal layer with a liquid etchant, and   removing the patterned mask and the hetero layer.   
     
     
         9 . The method as claimed in  claim 8 , wherein the conductive metal layer comprises one selected from the group consisting of copper and a copper alloy. 
     
     
         10 . The method as claimed in  claim 9 , wherein the hetero layer comprises nickel. 
     
     
         11 . The method as claimed in  claim 10 , wherein the liquid etchant is FeCl 3 . 
     
     
         12 . The method as claimed in  claim 9 , wherein the hetero layer comprises tin. 
     
     
         13 . The method as claimed in  claim 8 , wherein the hetero layer has a thickness smaller than that of the conductive metal layer. 
     
     
         14 . A method of making fine-pitch circuit lines, comprising the steps of:
 preparing an insulative substrate;   disposing a conductive metal layer on the insulative substrate;   disposing on a top surface of the conductive metal layer a hetero layer having an etching rate smaller than that of the conductive metal layer;   forming a patterned mask of circuit lines on the hetero layer;   removing the portion of the hetero layer that is located above a to-be-etched portion of the conductive metal layer;   etching the to-be-etched portion of the conductive metal layer with a liquid etchant, and   removing the patterned mask and the hetero layer.   
     
     
         15 . A method of making fine-pitch circuit lines, comprising the steps of:
 preparing an insulative substrate;   disposing a conductive metal layer on the insulative substrate;   forming a patterned mask of circuit lines on the conductive metal layer;   disposing on the portion of a top surface of the conductive metal layer that is intended not to be etched off a hetero layer having an etching rate smaller than that of the conductive metal layer;   removing the patterned mask;   etching the conductive metal layer with a liquid etchant, and   removing the hetero layer.   
     
     
         16 . The method as claimed in  claim 15 , wherein the liquid etchant comprises hydrogen peroxide and sulfuric acid.