Atomic Layer Epitaxy of Silicon

Two methods are proposed and demonstrated successfully for low temperature atomic layer epitaxy (ALE) of Si, where H atoms play essential roles. The first method is the use of H as a self-limiting factor. Trisilane (Si3H8) was used as source gas and the substrate temperature was modulated in order to alternate steps in an ALE cycle. When the temperature was less than 380°C in the adsorption step and more than 520°C in the desorption step, respectively, the grown layer thickness per cycle was 0.8 ML/cycle. The second method is the use of atomic H as an active reducer of a self-limiting factor. A clean surface was exposed to dichlorosilane (SiH2Cl2) as source gas to grow an Si monolayer covered with CI. Next, atomic H was injected to reduce CI from the surface. An ideal monolayer growth was obtained with the substrate temperature over 540°C.