Method for fabricating fin transistor

Abstract

A method for fabricating a fin transistor includes patterning a first pad layer provided over a substrate using an isolation mask, etching the substrate using the isolation mask and the first pad layer to form trenches, filling the trenches with an insulating material to form isolation structures, etching the isolation structures within the trenches using a gas having a high selectivity ratio of the insulating material to the first pad layer to form fin structures, forming a gate insulating layer over the fin structures, and forming a conductive layer over the gate insulating layer.

1 . A method for fabricating a saddle-type fin transistor, the method comprising:
 forming a pad layer over a substrate;   etching a substrate to form first and second trenches, the first and second trenches defining a portion of the substrate therebetween;   filling the first and second trenches with an isolation material to form first and second isolation structures, respectively, wherein the pad layer is provided over the portion of the substrate;   etching the first and second isolation structures using a gas having a high selectivity ratio of the isolation material to the pad layer, so that the portion of the substrate protrudes above an upper surface of the etched first and second isolation structures;   removing the pad layer to expose an upper surface of the portion of the substrate; and   etching the portion of the substrate to reduce the height of the portion to form a saddle-type fin.   
   
   
       2 . The method of  claim 1 , wherein the pad layer comprises a nitride-based material. 
   
   
       3 . The method of  claim 2 , wherein etching the first and second isolation structures comprises using a gas including one selected from a group consisting of a gas containing a high content of carbon, a gas containing high contents of carbon and hydrogen, and a combination thereof. 
   
   
       4 . The method of  claim 3 , wherein the gas containing the high content of carbon includes a C x F y  gas, where x≧2 and y≧1. 
   
   
       5 . The method of  claim 4 , wherein the C x F y  gas includes one selected from a group consisting of C 2 F 6 , C 3 F 8 , C 4 F 6 , and C 5 F 8 . 
   
   
       6 . The method of  claim 3 , wherein the gas containing high contents of carbon and hydrogen includes a C x H y F, gas, where x≧1, y≧2, and z≧1. 
   
   
       7 . The method of  claim 6 , wherein the C x H y F z  gas includes CH 2 F. 
   
   
       8 . The method of  claim 7 , wherein the first and second isolation structures are etched at least to a depth of 100 Å, wherein the exposed portion of the substrate is etched by 800 Å or more. 
   
   
       9 . The method of  claim 1 , wherein the first and second isolation structures include oxide.