Atomic layer processing for doping of SiGe

Atomic layer processing has been demonstrated for doping of SiGe during Reduced Pressure Chemical Vapour Deposition (RPCVD) in a commercial single wafer reactor. Atomic level control of dose and location has been obtained for B doping using B₂H₆ and for P doping using PH₃. The main idea of atomic layer processing is the separation of adsorption of the reactant gases from the deposition process. By this way, self-limitation has been shown for P doping. By lowering the temperature for B₂H₆ exposure (100 °C), the non-self-limiting character of the B doping process can be changed to self-limitation. By this manner, very shallow doping profiles with low sheet resistance have been obtained, capable for future ultra-shallow junction applications. P atomic layer doping is shown to be suitable for the creation of steep and narrow doping profiles suitable for high-performance pnp Heterojunction Bipolar Transistors (HBTs). This result, together with the already demonstrated usage of B atomic layer doping for npn HBTs, demonstrates the capability of the atomic layer processing approach for future devices with critical requirements for dopant dose and location control.