Semiconductor device and method of manufacturing the same

Abstract

A first insulating film is formed on a semiconductor substrate. A first interconnection is formed in a trench formed in the first insulating film. A first barrier film is formed between the first interconnection and first insulating film. A second insulating film is formed on the upper surface of the first interconnection, and in a first hollow portion between the side surface of the first barrier film and the first insulating film. The second insulating film is formed from the upper surface of the first interconnection to a depth higher than the bottom surface of the first interconnection. The first hollow portion is formed below the bottom surface of the second insulating film.

1 . A semiconductor device manufacturing method comprising:
 forming a first insulating film on a semiconductor substrate;   forming a trench in the first insulating film;   forming a first barrier film on side and bottom surfaces of the trench;   forming a first interconnection on the first barrier film in the trench; and   forming a first hollow portion between the first barrier film and the first insulating film by removing a low-carbon (C)-concentration portion of the first insulating film which exists near a side surface of the first barrier film.   
     
     
         2 . The method according to  claim 1 ,
 further comprising forming a second insulating film on an upper surface of the first interconnection, and in the first hollow portion between the side surface of the first barrier film and the first insulating film, the second insulating film being formed from the upper surface of the first interconnection to a depth higher than a bottom surface of the first interconnection, the first hollow portion remaining below the second insulating film.   
     
     
         3 . The method according to  claim 2 , wherein
 the first insulating film includes a lower film and an upper film formed on the lower film, the first hollow portion includes a lower hollow portion between the side surface of the first barrier film and the lower film, and an upper hollow portion between the side surface of the first barrier film and the upper film, and a width of the lower hollow portion is larger than that of the upper hollow portion, and   the second insulating film is formed in the lower hollow portion.   
     
     
         4 . The method according to  claim 1 , wherein the first insulating film is made of a film containing carbon (C), and a region having a carbon concentration lower than that of other portions of the first insulating film is formed in a bottom surface of the trench formed in the first insulating film. 
     
     
         5 . The method according to  claim 1 , wherein the first barrier film is a self-forming barrier film formed by annealing the first interconnection. 
     
     
         6 . The method according to  claim 1 , wherein the first barrier film and the second insulating film prevent diffusion of a material contained in the first interconnection. 
     
     
         7 . The method according to  claim 1 , wherein the first interconnection contains a Cu film. 
     
     
         8 . The method according to  claim 2 , further comprising:
 forming a third insulating film on the second insulating film;   forming a second interconnection in a trench formed in the third insulating film;   forming a second barrier film between the second interconnection and the third insulating film; and   forming a fourth insulating film on an upper surface of the second interconnection, and in a second hollow portion between a side surface of the second barrier film and the third insulating film, the fourth insulating film being formed from the upper surface of the second interconnection to a depth higher than a bottom surface of the second interconnection, and the second hollow portion being formed below a bottom surface of the fourth insulating film.   
     
     
         9 . The method according to  claim 8 ,
 further comprising forming a via contact hole in a trench formed in the third insulating film between the first interconnection and the second interconnection, the third insulating film being made of a film containing carbon (C), a region having a carbon concentration lower than that of other portions of the third insulating film being formed in a side surface of the trench formed in the third insulating film.