Semiconductor device having gate insulating film of silicon oxide and silicon nitride films

Abstract

Provided is an improved fabrication process for a semiconductor device by means of which in fabrication of insulated gate semiconductor devices having gate insulating films including silicon oxide films of different thickness, no contamination from a photoresist is ensured in a silicon oxide film, generation of defects in the silicon oxide film to be otherwise caused by aqueous solution treatments is suppressed, and thereby variability of characteristics among the semiconductor devices is suppressed. A silicon oxide film of a gate insulating film is formed on a semiconductor surface, a silicon nitride film is formed thereon by means of a chemical vapor deposition method using monosilane and ammonia as a source gas prior to formation of a resist film, the resist film is selectively formed on the surface, part of the silicon nitride film not covered by the resist film and the silicon oxide film therebeneath are removed to expose a semiconductor surface, the exposed semiconductor surface is oxidized to form a second silicon oxide film having a thickness different from that of the previously described silicon oxide film, and gate electrodes are formed on the respective insulating films.

What is claimed is:  
     
         1 . A semiconductor device, comprising a gate insulating film having a silicon oxide film containing substantially no carbon provided on a semiconductor region and a silicon nitride film containing substantially no chlorine provided on the silicon oxide film, and a gate electrode provided on the gate insulating film.  
     
     
         2 . A semiconductor device, comprising: 
 a first insulated gate semiconductor device comprising a first gate insulating film having a first silicon oxide film containing substantially no carbon formed on a first surface of a semiconductor region and a first silicon nitride film containing substantially no chlorine formed on the first silicon oxide film, and a first gate electrode formed on the first gate insulating film; and    a second insulated gate semiconductor device comprising a second gate insulating film of a second silicon oxide film with a thickness different from that of the first silicon oxide film provided on a second surface spaced apart from the first surface of the semiconductor region, and a second gate electrode provided on the second gate insulating film.    
     
     
         3 . A semiconductor device, comprising: 
 a first insulated gate semiconductor device comprising a first gate insulating film including a first silicon oxide film provided on a first surface of a semiconductor region and a first silicon nitride film containing substantially no chlorine provided on the first silicon oxide film, and a first gate electrode provided on the first gate insulating film; and    a second insulated gate semiconductor device comprising a second gate insulating film including a second silicon oxide film with a thickness different from that of the first silicon oxide film provided on a second surface different from the first surface of the semiconductor region and a second silicon nitride film containing substantially no chlorine provided on the second silicon oxide film, and a second gate electrode provided on the second gate insulating film.