A low-thermal-budget in situ doped multilayer silicon epitaxy process for MOSFET channel engineering

This paper describes an in situ boron-doped, multilayer epitaxial silicon p rocess that can be used to obtain doping profiles for channels in the deep- submicron regime. We have extensively studied lightly doped channel structu res in which an intrinsic silicon layer is grown an in situ doped epitaxial silicon film. Low-thermal-budget processing is achieved by the ultrahigh-v acuum rapid thermal chemical vapor deposition technique which combines low- temperature surface preparation and deposition (less than or equal to 800 d egrees C) while providing high growth rates using disilane (Si2H6). Boron d oping is achieved using diborane (B2H6) diluted in hydrogen (500 ppm) as th e precursor. Temperature and gas switching are compared in terms of doping transition, interface contamination (carbon and oxygen incorporation), and impurity diffusion upon annealing. Our results reveal that for a contaminat ion-free epitaxial silicon interface, interfacial carbon contamination must be eliminated or reduced to a minimum level. Using this process, short-cha nnel n-channel metal-oxide semiconductor devices (L-eff = 0.12 mu m) have b een fabricated for the first time demonstrating the potential use of the te chnique, It was found that lightly doped channel metal-oxide semiconductor field effect transistors are more easily scalable into the 0.1 mu m regime with superior short-channel characteristics. (C) 1999 The Electrochemical S ociety. S0013-4651(98)07-005-0. All rights reserved.