Integrated circuit substrate and method of making

Abstract

According to various embodiments of the present disclosure, a substrate for an integrated circuit includes a dielectric layer. The substrate further includes a conductive layer extending in an x or y direction. The conductive layer is at least partially embedded within the dielectric layer. The conductive layer includes a via having a first end and an opposite second end. The via has a first height in a z-direction and a constant cross-sectional shape between the first end and the second end. A trace is adjacent to the via and has a second height in the z-direction that is different than the first height.

What is claimed is: 
     
         1 . A substrate for an integrated circuit, the substrate comprising:
 a dielectric layer; and   a metallic transmission line, comprising:
 a first region having a first width in an x or y direction and a first height in a z-direction; and 
 a second region having a second width in the x or y direction and a second height in the z-direction, 
 wherein the first height is greater than the second height and the first region has a constant cross-sectional shape in the z-direction. 
   
     
     
         2 . The substrate of  claim 1 , wherein the dielectric layer comprises a dielectric material chosen from an epoxy laminate, polytetrafluoroethylene, phenolic cotton pater, woven glass, or mixtures thereof. 
     
     
         3 . The substrate of  claim 2 , wherein the dielectric layer comprises a plurality of individual layers of the dielectric material. 
     
     
         4 . The substrate of  claim 1 , wherein the dielectric layer comprises different dielectric materials. 
     
     
         5 . The substrate of  claim 1 , wherein the individual layers of the dielectric material comprise a same dielectric material. 
     
     
         6 . The substrate of  claim 1 , wherein the metallic transmission line comprises copper. 
     
     
         7 . The substrate of  claim 1 , wherein the constant cross-sectional shape is chosen from a circle, an oval, a triangle, a square, a rectangle, a pentagon, a hexagon, a heptagon, and an octagon. 
     
     
         8 . The substrate of  claim 1 , wherein the first height ranges from about 1.5 times to about 4 times greater than the second height. 
     
     
         9 . The substrate of  claim 1 , wherein a width of the first region ranges from about 1.5 times to about 4 times greater than a width of the second region. 
     
     
         10 . The substrate of  claim 1 , wherein the first region is a via and the second region is a trace. 
     
     
         11 . A method for forming a substrate, the method comprising:
 contacting a first patterned region with an electrolytic copper composition comprising:
 a copper salt; and 
 a rate controlling agent; 
   contacting a second patterned region with the electrolytic copper composition comprising:
 a copper salt; and 
 a rate controlling agent; 
   wherein a first quantity of the rate controlling agent in the first region differs from second quantity of the rate controlling agent in the second region and the first and second regions are defined by plurality of dry film resist elements, wherein a first distance in an x or y direction in the first region between a first pair of adjacent dry film resist elements is greater than a second distance in the x or y direction in the second region between a second pair of adjacent dry film resist elements;   applying a voltage to the electrolytic copper composition to plate a copper layer in the patterned regions;   removing the dry film resist elements; and   laminating a second dielectric layer on the copper layer.   
     
     
         12 . The method of  claim 11 , wherein the copper salt is chosen from cupric sulfate, copper chloride, or a mixture thereof. 
     
     
         13 . The method of  claim 11 , wherein the rate controlling agent ranges from about 20 wt % to about 95 wt % of the electrolytic copper composition. 
     
     
         14 . The method of  claim 11 , wherein the rate controlling agent is chosen from polyethers, polyethylene glycol, polypropylene glycol, nitrogen bearing heterocyclic aromatic compounds, nitrogen bearing non-heterocyclic aromatic compounds, large molecular weight polyoxy-alkyl type compounds, high molecular weight polymers, sulfur-based organic molecules, disulfides, and surfactants.