Atomically Controlled Technology for Future Si-Based Devices

One of the main requirements for Si-based Ultrasmail device is atomic-order control of process technology. Here we show the concept of atomic-level processing based on atomic-order surface reaction control. The main idea of the atomic layer approach is the separation of the surface adsorption of reactant gases from the reaction process. Self-limiting formation of 1-3 atomic layers of group IV or related atoms in the thermal adsorption and reaction of hydride gases (SiH₄, GeH₄, NH₃, PH₃, CH₄ and SiH₃CH₃) on Si(100) and Ge(100) are generalized based on the Langmuir-type model. Si or SiGe epitaxial growth over the N, P and B layer already-formed on Si(100) or SiGe(100) surface is achieved. It is found that higher level of electrical P atoms exist in such film, compared with doping under thermal equilibrium conditions. Furthermore, the capability of atomically controlled processing for doping of advanced devices with critical requirements for dose and location control is demonstrated for the base doping of SiGe:C heterojunction bipolar transistors (HBTs). These results open the way to atomically controlled technology for ultra-large-scale integrations.