The role of boron segregation and transient enhanced diffusion on reverse short channel effect

Abstract

This paper presents the results of an experiment that examines the effects of standard channel formation process steps on boron channel profiles. The experiment is specifically designed to determine the role of various processing steps on reverse short channel effect (RSCE). In the experiment defect-free silicon films, uniformly doped with boron, were grown epitaxially. The samples were then subjected to the processing steps associated with channel profile formation. A gate oxide was grown, then silicon was implanted to simulate the damage due to a source/drain implant. Finally, a damage anneal was done. The resultant experimental dopant profiles as measured using SIMS reveal an important effect which may cause reverse short channel effect. Boron segregation during gate oxidation significantly reduces the boron concentration near the silicon-oxide interface. Subsequent diffusions show that in the presence of damage, the transient enhanced diffusion of boron refills the dopant lost during segregation. In the absence of damage, the profile remains as it was after gate oxidation.