Semiconductor manufacturing method including forming additional active layer

Abstract

A semiconductor device and a manufacturing method thereof which is suited for forming both a transistor for a memory cell and a transistor for a high voltage circuit part on one semiconductor substrate, and moreover, has little deterioration of an electrical characteristic in the structure that a sidewall insulating film in a shared contact plug part is removed is provided. An active layer ( 16 ) is formed by performing an additional impurity injection on a part where a sidewall insulating film is removed in a forming portion of a shared contact plug ( 18 a ). An insulating film is laminated in a high voltage circuit part (AR 1 ) and a sidewall insulating film ( 10 d ) of wide width is formed. According to this, a forming width of a sidewall insulating film ( 10 a ) can be made small in a MOS transistor for a memory cell part (AR 2 ), and a forming width of a sidewall insulating film ( 10 d ) can be made large in a MOS transistor for a high voltage circuit part. Thereupon, in the high voltage circuit part (AR 1 ), a source/drain active layer can be formed in the position more distant from a gate electrode.

What is claimed is:  
     
         1 . A semiconductor device, comprising: 
 a semiconductor substrate;    a first transistor which includes a first gate electrode which is formed on said semiconductor substrate, a first sidewall insulating film which is formed on a side of said first gate electrode on said semiconductor substrate and first source/drain active layers which are formed in said semiconductor substrate; and    a second transistor which includes a second gate electrode which is formed on said semiconductor substrate, a second sidewall insulating film which is formed on a side of said second gate electrode on said semiconductor substrate and second source/drain active layers which are formed in said semiconductor substrate, wherein    layers of insulating films which compose said second sidewall insulating film are more in number than layers of an insulating film which compose said first sidewall insulating film, and accordingly, a width of said second sidewall insulating film in a channel direction of said second transistor is larger than a width of said first sidewall insulating film in a channel direction of said first transistor.    
     
     
         2 . The semiconductor device according to  claim 1 , wherein 
 said first sidewall insulating film includes a silicon nitride film, and    said second sidewall insulating film includes a silicon nitride film and a silicon oxide film.