Semiconductor device and manufacturing method thereof

Abstract

In the semiconductor device, in order to meet the demand of reduced diameter of a contact hole along with the miniaturization of the semiconductor device, an anti-HF side wall film which is not etched by a hydrofluoric acid, formed of an isolating film such as nitride film, is provided on the side wall of contact hole. Further, a second impurity region which is connected to one of the pair of n type source/drain regions and a first impurity region reaching a p type isolation region are provided in silicon substrate 1 near the lower end of contact hole. Because of this structure, it becomes possible to prevent expansion of the diameter for forming the interconnection layer, as desired in the miniaturized semiconductor device, and therefore a semiconductor device and manufacturing method thereof which stabilize operation characteristic of the semiconductor device can be provided.

What is claimed is:  
     
         1 . A semiconductor device, comprising: 
 a semiconductor substrate having a main surface;    an element isolation region for defining an element forming region on the main surface of said semiconductor substrate;    an isolation region provided in a strip-shape and having a peak impurity concentration at a prescribed depth position from the main surface of said semiconductor substrate;    a connection hole provided piercing through said element isolating region;    an anti-HF side wall film not etched by hydrofluoric acid, provided to cover a side wall of said connection hole at least near a lower end of said connection hole;    an interconnection layer provided to fill an inner portion of said connection hole; and    an impurity region provided in said semiconductor substrate extending from the lower end of said connection hole to said isolation region.    
     
     
         2 . The semiconductor device according to  claim 1 , wherein said anti-HF side wall film is a nitride film.  
     
     
         3 . The semiconductor device according to  claim 2 , wherein 
 said impurity region includes a first impurity region provided to connected said interconnection layer to said isolation region, and a second impurity region provided near the lower end of said connection hole and connected to said interconnection layer.    
     
     
         4 . The semiconductor device according to  claim 1 , wherein said anti-HF side wall film is either a polysilicon film or an amorphous silicon film.  
     
     
         5 . A method of manufacturing a semiconductor device, comprising the steps of: 
 forming an element isolating region for defining an element forming region on a semiconductor substrate having a main surface;    introducing an impurity to an entire surface of said semiconductor substrate to form a strip-shaped isolation region having a peak impurity concentration at a prescribed depth position from the main surface of said semiconductor substrate;    forming a connection hole piercing through said element isolating region;    forming an anti-HF side wall film not etched by hydrofluoric acid, provided to cover a side wall of said connection hole at least near a lower end of said connection hole;    introducing an impurity to said semiconductor substrate through said connection hole to form a first impurity region reaching from the lower end of said connection hole to said isolation region;    washing an inner portion of said connection hole by hydrofluoric acid; and    forming an interconnection layer to fill the inner portion of said connection hole.    
     
     
         6 . The method of manufacturing a semiconductor device according to  claim 5 , wherein a polysilicon film or an amorphous silicon film is formed in said step of forming the anti-HF side wall film.  
     
     
         7 . The method of manufacturing a semiconductor device according to  claim 5 , wherein said step of forming said anti-HF side wall film includes the steps of forming a nitride film, and before said anti-HF side wall film is formed on the side wall of said connection hole, introducing an impurity to said semiconductor substrate through said connection hole to form a second impurity region near the lower end of said connection hole.