Semiconductor device having opening and method of fabricating the same

Abstract

A semiconductor device capable of compatibly suppressing a microloading effect (irregular etching) and over-etching also in formation of a fine contact hole requiring a high aspect ratio is obtained. This semiconductor device comprises a first conductive part, an insulator film having an opening formed on the first conductive part and a second conductive part electrically connected with the first conductive part through the opening. The insulator film includes an upper insulator film and a lower insulator film, stacked/formed at least around a connection part between the first conductive part and the second conductive part, consisting of different materials. Thus, when employing a material having a higher etching selection ratio than the upper insulator film for the lower insulator film, the first conductive part is prevented from over-etching also when etching is performed through a high-concentration plasma device with which a high etching selection ratio of the first conductive part is hard to attain for suppressing a microloading effect (irregular etching).

What is claimed is:  
     
         1 . A semiconductor device comprising: 
 a first conductive part;    an insulator film having an opening formed on said first conductive part; and    a second conductive part electrically connected to said first conductive part through said opening, wherein    said insulator film includes an upper insulator film and a lower insulator film, stacked/formed at least around a connection part between said first conductive part and said second conductive part, consisting of different materials.    
     
     
         2 . The semiconductor device according to    claim 1   , wherein 
 said lower insulator film contains a material having a higher etching selection ratio than said upper insulator film.    
     
     
         3 . The semiconductor device according to    claim 2   , wherein 
 said first conductive part contains a material having a higher etching selection ratio than said lower insulator film.    
     
     
         4 . The semiconductor device according to    claim 3   , wherein 
 said first conductive part includes a silicified element electrode,    said lower insulator film includes a silicon nitride film, and    said upper insulator film includes a silicon oxide film.    
     
     
         5 . The semiconductor device according to    claim 4   , wherein 
 said element electrode includes a silicified gate electrode, a silicified source electrode and a silicified drain electrode.    
     
     
         6 . The semiconductor device according to    claim 4   , wherein 
 said silicon nitride film is formed to be in contact with areas of the surfaces of said silicified electrodes except those exposed in said opening.    
     
     
         7 . The semiconductor device according to    claim 2   , wherein 
 said lower insulator film includes an SOG film.    
     
     
         8 . A method of fabricating a semiconductor device, comprising steps of: 
 forming an insulator film including a multilayer film of an upper insulator film and a lower insulator film having a higher etching selection ratio than said upper insulator film on a first conductive part;    etching said insulator film thereby forming an opening reaching said first conductive part; and    forming a second conductive part connected with said first conductive part through said opening.    
     
     
         9 . The method of fabricating a semiconductor device according to    claim 8   , wherein 
 said first conductive part contains a material having a higher etching selection ratio than said lower insulator film.    
     
     
         10 . The method of fabricating a semiconductor device according to    claim 8   , further comprising a step of silicifying said first conductive part in advance of said step of forming said insulator film.  
     
     
         11 . The method of fabricating a semiconductor device according to    claim 10   , wherein 
 said first conductive part includes a gate electrode, a source electrode and a drain electrode, and    said step of silicifying said first conductive part includes a step of silicifying the surfaces of said gate electrode, said source electrode and said drain electrode.    
     
     
         12 . The method of fabricating a semiconductor device according to    claim 8   , wherein 
 said lower insulator film includes a silicon nitride film,    said upper insulator film includes a silicon oxide film, and    said step of forming said opening includes a step of forming said opening by etching said upper insulator film and said lower insulator film by dry etching with gas having a composition of C x H y F z .    
     
     
         13 . The method of fabricating a semiconductor device according to    claim 12   , wherein 
 said gas consisting of C x H y F z  includes gas consisting of C 4 H 8 .    
     
     
         14 . The method of fabricating a semiconductor device according to    claim 12   , wherein 
 said silicon nitride film forming said lower insulator film is formed to be in contact with the surface of said first conductive part.    
     
     
         15 . The method of fabricating a semiconductor device according to    claim 8   , wherein 
 said step of forming said opening is carried out by dry etching through a high-concentration plasma device.    
     
     
         16 . The method of fabricating a semiconductor device according to    claim 8   , wherein 
 said lower insulator film includes an SOG film.