Semiconductor device and method of manufacturing the semiconductor device

Abstract

The invention provides a semiconductor device having stability in device characteristics, in which variation in contact resistance between silicon and poly-silicon or between poly-silicon and poly-silicon is reduced. The invention also provides a method of manufacturing the semiconductor device. In the cleaning process before forming an upper layer poly-silicon film 11, an H2O2 treatment is conducted to form a thin uniform oxide film 20 of about 0.5 nm to 10 nm in thickness (to the extent of permitting an impurity to diffuse through the film) on the surface of silicon. After forming the upper layer poly-silicon film 11, a removed portion is uniformly formed on the thin uniform oxide film by applying a short time high temperature annealing treatment by RTP (Rapid Thermal Process).

What is claimed is:  
     
         1 . A semiconductor device comprising: 
 a silicon semiconductor layer of first conductivity type;    an insulating oxide film having an opening and laminated on said silicon semiconductor layer of first conductivity type;    a first poly-silicon film formed on said insulating oxide film and having an opening located at the same position as the opening formed in said insulating oxide film;    an impurity diffused layer of second conductivity type formed on an exposed portion of said silicon semiconductor layer of first conductivity type, the exposed portion being exposed through the openings of said insulating oxide film and said first poly-silicon film;    a second poly-silicon film formed on said first poly-silicon film and in said openings; and    a thin uniform oxide film serving as a contact and having a removed portion uniformly formed between said impurity diffused layer of second conductivity type and said second poly-silicon film and between said first poly-silicon film and said second poly-silicon film.    
     
     
         2 . A method of manufacturing a semiconductor device comprising the steps of: 
 laminating an insulating oxide film and a first poly-silicon film sequentially in order on a silicon semiconductor layer of first conductivity type;    forming an opening by selectively etching said insulating oxide film and said first poly-silicon film and exposing a part of said silicon semiconductor layer of first conductivity type through said opening;    forming an impurity diffused layer of second conductivity type by implanting an impurity of second conductivity type into the exposed portion of said silicon semiconductor layer of first conductivity type;    removing a natural oxidation film from said impurity diffused layer of second conductivity type and said first poly-silicon film by applying HF (hydrofluoric acid) treatment;    forming a thin uniform oxide film on the surface of said impurity diffused layer of second conductivity type and on the surface of said first poly-silicon film from which the natural oxidation film has been removed;    forming a second poly-silicon film on the entire surface of the substrate and implanting the impurity of second conductivity type in said second poly-silicon film;    activating said impurity of second conductivity type implanted in said second poly-silicon film and diffusing said impurity of second conductivity type into said first poly-silicon film through said thin uniform oxide film; and    forming uniformly a removed portion in said thin uniform oxide film by applying a high temperature annealing treatment for a short time and forming a thin uniform oxide film serving as contact having the uniformly formed removed portion.    
     
     
         3 . The method of manufacturing a semiconductor device according to  claim 2 , wherein said thin uniform oxide film is formed by H2O2 (hydrogen peroxide) treatment.  
     
     
         4 . The method of manufacturing a semiconductor device according to  claim 2 , wherein said thin uniform oxide film is about 0.5 nm to 10 nm in thickness.  
     
     
         5 . The method of manufacturing a semiconductor device according to claims  2 , wherein temperature in the high temperature annealing treatment for a short time is about 950° C. to 1150° C., and treating time is about 10 sec to 3 min.