Dual-damascene interconnects without an etch stop layer by alternating ILDs

Abstract

A dual-damascene process where first alternate ILDs are made of a first material and second alternate ILDs are made of a second material. Each material is etchable at a faster rate than the other in the presence of different etchant such as for an organic polymer and an inorganic low k material. This allows the ILDs to be deposited alternately on one another without an etchant stop layer thereby reducing capacitance.

1 - 24 . (canceled)  
   
   
       25 . A method for fabricating an integrated circuit comprising: 
 depositing a first ILD entirely of a first material;    forming vias and conductors in the first ILD;    forming a second ILD directly on the first ILD entirely of a second material;    etching openings in the second ILD with a first etchant that etches the second material faster than the first material;    forming a third ILD entirely of the first material directly on the second ILD; and    etching openings in the third ILD with a second etchant that etches the first material faster than the second material.    
   
   
       26 . The method defined by  claim 25  wherein the second material comprises a carbon-based oxide.  
   
   
       27 . The method defined by  claim 26  wherein the first material comprises a polymer based dielectric.  
   
   
       28 . The method defined by  claim 27  wherein the second material is etched with a fluorocarbon.  
   
   
       29 . The method defined by  claim 28  wherein the first material is etched with oxygen or hydrogen.  
   
   
       30 . The method defined by  claim 25  including the steps of forming vias and conductors in the second and third ILDs.  
   
   
       31 . A method of fabricating an integrated circuit comprising: 
 forming first alternate interlayer dielectrics (ILDs) entirely of a first material; forming second ILDs intermediate between the first ILDs entirely of a second material where the second are material is etchable at a faster rate than the first material by a first etchant and where the second material is etchable at a faster rate than the first material by a second etchant.    
   
   
       32 . The method defined by  claim 31  wherein the first material comprises an organic based material, and wherein the second material comprises a non-organic based material.  
   
   
       33 . The method defined by  claim 32  including forming vias and conductors in each of the ILDs.  
   
   
       34 . The method defined by  claim 33  wherein the vias and conductors are formed with a dual-damascene process.  
   
   
       35 . (canceled)  
   
   
       36 . The method defined by  claim 31  wherein conductors in the first and second layer are covered by a shunting material.