Semiconductor device and method for fabricating semiconductor device

Abstract

A method for fabricating a semiconductor device, comprising: forming n-channel field-effect transistors on a silicon substrate; forming a first insulating film covering the field-effect transistors; shrinking the first insulating film; forming a second insulating film over the first insulating film; and shrinking the second insulating film, wherein the forming an insulating film covering the field-effect transistors and the shrinking the insulating film are repeated a plurality of time.

1 . A method for fabricating a semiconductor device, comprising: forming n-channel field-effect transistors on a silicon substrate; forming a first insulating film covering the field-effect transistors; shrinking the first insulating film; forming a second insulating film over the first insulating film; and shrinking the second insulating film, wherein the forming an insulating film covering the field-effect transistors and the shrinking the insulating film are repeated a plurality of time. 
     
     
         2 . The method for fabricating a semiconductor device according to  claim 1 , wherein a thickness of the first insulating film and the second insulating film are in a range from 5 to 60 nm. 
     
     
         3 . The method for fabricating a semiconductor device according to  claim 1 , wherein the forming the first insulating film and the second insulating film covering the field-effect transistors are performed by depositing a silicon nitride by Chemical Vapor Deposition process. 
     
     
         4 . The method for fabricating a semiconductor device according to  claim 3 , wherein the Chemical Vapor Deposition process is performed by using a mixed gas of silane and ammonium. 
     
     
         5 . The method for fabricating a semiconductor device according to  claim 3 , wherein the Chemical Vapor Deposition process is performed in a range from 200° C. to 450° C. 
     
     
         6 . The method for fabricating a semiconductor device according to  claim 1 , wherein the shrinking the insulating film is performed by Ultra Violet exposure. 
     
     
         7 . The method for fabricating a semiconductor device according to  claim 6 , wherein the shrinking the first insulating film and the second insulating film are performed by an Ultra Violet exposure and a plasma exposure. 
     
     
         8 . The method for fabricating a semiconductor device according to  claim 7 , wherein the plasma exposure is performed by using a nitrogen plasma or a hydrogen plasma or an ammonium plasma. 
     
     
         9 . A method for fabricating a semiconductor device, the method comprising: forming n-channel field-effect transistors on a silicon substrate; shrinking a first insulating film after forming a first insulating film covering the field-effect transistors; and forming a second insulating film on the first insulating film and shrinking the second insulating film. 
     
     
         10 . The method for fabricating a semiconductor device according to  claim 9 , wherein a thickness of the first insulating film is thinner than a thickness of the second insulating film.