Method for fabricating semiconductor device

A method for fabricating a semiconductor device, comprising the steps of:

• forming a device separation region to section a first device forming region and a second device forming region on a substrate with a silicon on insulator structure;
• forming a gate oxide film on respective parts of said first and second device forming regions;
• forming gate electrodes on said gate oxide film of said first and second device forming regions;
• introducing a first conductivity type impurity into said first and second device forming regions to form a channel region of a first channel type transistor on at least said first device forming region;
• and
• introducing a second conductivity type impurity into said first and second device forming regions while using said gate electrodes as a mask to form a source-drain region of said first channel type transistor on at least said first device forming region;
• introducing said second conductivity type impurity selectively into said second device forming region to form a channel region of a second channel type transistor on said second device forming region;
• and
• introducing said second conductivity type impurity selectively into said second device forming region while using said gate electrodes as a mask to form a source-drain region of said second channel type transistor on said second device forming region.