Multiple spacer patterning schemes

Abstract

The present disclosure provides forming nanostructures utilizing multiple patterning process with good profile control and feature transfer integrity. In one embodiment, a method for forming features on a substrate includes forming a first mandrel layer on a material layer disposed on a substrate. A first spacer layer is conformally formed on sidewalls of the first mandrel layer, wherein the first spacer layer comprises a doped silicon material. The first mandrel layer is selectively removed while keeping the first spacer layer. A second spacer layer is conformally formed on sidewalls of the first spacer layer and selectively removing the first spacer layer while keeping the second spacer layer.

What is claimed is: 
     
         1 . A method for forming features on a substrate comprising:
 forming a first patterned mask layer on a material layer disposed on a substrate;   forming a second patterned mask layer on the material layer wherein the second patterned mask layer is conformally deposited on sidewalls of the first patterned mask layer;   forming a third patterned mask layer ( 608 ) on the material layer, wherein the third patterned mask layer is conformally deposited on sidewalls of the second patterned mask layer, wherein the first patterned mask layer is fabricated from a material different from that of the second patterned mask layer and the first patterned mask layer is fabricated from a same material as the third patterned mask layer, wherein either the second patterned mask layer or the third patterned mask layer is fabricated from a material comprising Boron doped silicon, and the second patterned mask layer or the third patterned mask layer has vertically straight sidewalls and square corners and top surface profile; and   selectively removing the first patterned mask layer to define a first group of openings.   
     
     
         2 . The method of  claim 1 , wherein the second patterned mask layer reduces an opening width free of mask material between the sides of the first patterned mask layer. 
     
     
         3 . The method of  claim 2 , wherein the third patterned mask layer further reduces the opening width free of mask material between the sides of the first patterned mask layer. 
     
     
         4 . The method of  claim 1  further comprising:
 forming a fourth patterned mask layer on the third patterned mask layer wherein the fourth patterned mask layer is conformally deposited on sidewalls of the third patterned mask layer and an non-fill opening is maintained between the fourth patterned mask layer. 
 
     
     
         5 . The method of  claim 4  wherein the first, second, third and fourth pattern mask layers are fabricated with different materials to enhance etch selectivity therebetween. 
     
     
         6 . The method of  claim 4  wherein a pitch of the non-fill opening between the fourth patterned mask layer is equal to a pitch of the first patterned mask layer. 
     
     
         7 . The method of  claim 4  wherein a pitch of the non-fill opening between the fourth patterned mask layer is less than about 15 nm. 
     
     
         8 . The method of  claim 4  further comprising:
 targeting the first patterned mask layers and third patterned mask layers with an etching chemistry; and 
 selectively removing the first patterned mask layers and third patterned mask layers spaced from the non-fill opening by the fourth pattern mask layer to form openings. 
 
     
     
         9 . The method of  claim 8  wherein a pitch of the openings formed between the second pattern mask layer and the fourth patterned mask layer is equal to a pitch of the first patterned mask layer. 
     
     
         10 . The method of  claim 8  wherein a pitch of the openings formed between the second pattern mask layer and the fourth patterned mask layer is equal to a pitch of the non-fill opening between the fourth patterned mask layer. 
     
     
         11 . The method of  claim 8  wherein a pitch of the openings is between about 50 nm and about 150 nm. 
     
     
         12 . The method of  claim 11  wherein the pitch of the openings is about 80 nm. 
     
     
         13 . The method of  claim 8  further comprising:
 etching the material layer to form material openings in the material layer; and 
 removing the second pattern mask layer and the fourth patterned mask layer to leave the material layer. 
 
     
     
         14 . The method of  claim 13  further comprising:
 using the material layer as a hardmask for etching the substrate.