Elevated source/drain field effect transistor and method for making the same

Abstract

A gate oxide film ( ), a gate electrode ( ) and a gate cap insulating film ( ) are stacked on an active region of a p-type semiconductor substrate ( ), and an insulating side wall ( ) is formed, followed by BF ion implantation. Thus, a surface of the p-type semiconductor substrate becomes amorphous so that single-crystal silicon is prevented from epitaxially growing in the next process of depositing polysilicon ( ). Halo regions ( ) are formed using the BF ions having the opposite conductivity to a source/drain to reduce the short-channel effect. The substrate is then passed through a nitrogen purge chamber having a dew point kept at −100° C. to remove water molecules completely, and polysilicon ( ) is deposited. Because native oxide is prevented from growing at an interface between the active region and the polysilicon, source/drain regions ( ) formed later by implantation and diffusion of n-type impurity ions achieve a uniform junction depth.