Method for fabricating semiconductor device with porous dielectric structure

Abstract

The present application discloses a method for fabricating a semiconductor device. The method includes providing a substrate; forming two conductive features apart from each other over the substrate; forming a porous middle layer positioned between the two conductive features and adjacent to the two conductive features; depositing an energy-removable material between the two conductive features and adjacent to the two conductive features; and performing an energy treatment to transform the energy-removable material into a porous middle layer. The porosity of the porous middle layer is between about 25% and about 100%.

What is claimed is: 
     
         1 . A method for fabricating a semiconductor device, comprising:
 providing a substrate;   forming two conductive features apart from each other over the substrate;   forming a porous middle layer positioned between the two conductive features and adjacent to the two conductive features;   depositing an energy-removable material between the two conductive features and adjacent to the two conductive features; and   performing an energy treatment to transform the energy-removable material into a porous middle layer;   wherein a porosity of the porous middle layer is between about 25% and about 100%.   
     
     
         2 . The method for fabricating the semiconductor device of  claim 1 , wherein the energy-removable material comprises a base material and a decomposable porogen material. 
     
     
         3 . The method for fabricating the semiconductor device of  claim 2 , wherein an energy source of the energy treatment is heat, light, or a combination thereof. 
     
     
         4 . The method for fabricating the semiconductor device of  claim 3 , wherein the base material comprises methylsilsesquioxane or silicon oxide. 
     
     
         5 . The method for fabricating the semiconductor device of  claim 4 , further comprising forming a first stop layer on the substrate, wherein the first stop layer has a thickness between about 1 nm and about 50 nm. 
     
     
         6 . The method for fabricating the semiconductor device of  claim 5 , further comprising forming a plurality of fins on the first stop layer.