Method of channel doping using diffusion from implanted polysilicon

A process for fabricating a semiconductor device in a semiconductor substrate comprising:

• defining an integrated circuit device channel in the semiconductor substrate;
• forming an isolation structure laterally enclosing the integrated circuit device channel;
• forming a thin oxide layer overlying the semiconductor substrate and extending over the integrated circuit device channel;
• depositing a polysilicon blanket layer overlying the thin oxide layer;
• patterning a photoresist mask overlying the polysilicon blanket layer in alignment with the isolation structure, the pattern being selected to uniformly dope the integrated circuit device channel;
• implanting dopant impurities into the polysilicon blanket layer in regions unprotected by the photoresist mask;
• diffusing the dopant impurities from the polysilicon blanket layer through the thin oxide layer a controlled shallow depth and with a controlled uniform dopant concentration laterally into the integrated circuit device channel;
• removing the polysilicon blanket layer;
• and
• removing the thin oxide layer.