W delta doping in Si(1 0 0) using ultraclean low-pressure CVD

Abstract

W delta doping in Si epitaxial growth by WF6 and SiH4 reaction has been investigated using an ultraclean cold-wall low-pressure chemical vapor deposition (CVD) system. Atomic-layer order W deposition is performed on wet-cleaned Si(100) substrate at 100°C using WF6 and SiH4. Si epitaxial growth is achieved by SiH4 reaction at 480°C on 4×1013cm−2 W deposited Si(100), however, it is found that almost all the deposited W atoms segregate on the deposited Si film. It is also found that such segregation is suppressed by the atomic-order W diffusion into Si(100) substrate by the heat treatment at 520°C before the Si deposition. In the case of the Si film deposited on the 1.3×1014cm−2 W diffused Si, the reflection high-energy electron diffraction (RHEED) pattern indicates the crystallinity and the roughness degrade. In the case of the Si film deposited on the 5×1013cm−2 W diffused Si, the RHEED pattern shows streaks with Kikuchi lines. As a result, the W delta doping in the Si epitaxial growth is achieved, in which the W concentration is as high as 6×1020cm−3 and the incorporated W atoms is confined within 2nm-thick region.