US Patent 7745292 Method for fabricating a semiconductor gate structure

A method of making a semiconductor device is disclosed. A mask if formed over a first and a second region of a semiconductor body, and a vertical diffusion barrier is formed in a region between the first and second regions. A mask is then formed over the second region and the first region is left unmasked. The semiconductor body is exposed to a dopant, so that the first region is doped and the second region is blocked from the dopant by the mask and by the vertical diffusion barrier.