Process for forming a polysilicon layer having improved roughness after POCL3 doping
 An improved method for depositing the polysilicon layer from which a gate pedestal is later formed is described. Deposition takes place in two stages. Initially, the conventional deposition temperature of about 630.degree. C. is used. Then, when the intended thickness of polysilicon has been grown, the temperature is ramped down to about 560.degree. C., without interrupting the deposition process, and growth of the film continues to completion. This is followed by a standard doping step using POCl.sub.3. Polysilicon films formed in this way have been found to have very smooth surfaces because the topmost layer is less subject to uncontrolled grain growth. As a consequence, dielectric layers obtained by oxidizing such films exhibit superior breakdown voltages. 
Taiwan Semiconductor Manufacturing Company, Ltd.
H H H H H H
H01L H01L H01L H01L H01L H01L
inventional inventional inventional inventional inventional inventional
Chun-Chieh Chao-Yi Yu-Jen Te-Fu
Chang Lan Yu Tseng