(Invited) Atomic Control of Doping during Si Based Epitaxial Layer Growth Processes

Abstract

Atomic-level processing based on surface reaction control is used for B and P doping during Si, SiGe or Ge epitaxy. The concept of atomic layer processing is base on the separation of adsorption of the dopant gases from the layer growth. By this way the doping process is controlled by surface adsorption / desorption of dopant gas mainly. For B atomic layer doping of SiGe and pure Ge using B 2 H 6 , high doping levels and steep doping profiles have been reached. The process was found to be self-limited at ~100°C indicating preferred adsorption of B 2 H 6 on Si and Ge sites and suppression of B cluster formation. For P atomic layer doping on Si and SiGe self-limitation of the process has been observed for temperatures between 200-600°C allowing very precise dopant dose and location control. IntroductionSilicon based integrated circuits technology is reaching the nanometer scale region with lateral and vertical structures close to atomic dimensions. Moreover emerging research devices and technologies are under investigation to extend the CMOS technology further on or to evaluate solutions for beyond Si CMOS technologies like introducing Ge or III-V material channel replacement. As well for further scaling as for novel nanoelectronic device concepts advanced processing technologies at atomic level are requested. Very low temperature processing is required allowing creation and control of vertical and lateral structures at atomic level and the integration of new materials for emerging device concepts.Here we discuss the concept of atomic-level processing for doping of Si, SiGe and Ge based on atomic-order surface reaction control. The main idea of the atomic layer approach is the idea to control the process by surface reactions at very low temperatures (even at room temperature). By processing at low temperature the adsorption of reactant gases at the surface can be separated from the reaction process. By this way the process is controlled by the surface adsorption equilibrium only. The main concept of surface reaction limited processing is described in Figure 1. In a first step the surface of the wafer is exposed to the reacting gases at low temperature. According to the experimental ECS Transactions, 33 (6) 603-614 (2010) 10.1149/1.3487591 © The Electrochemical Society 603 ) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 169.230.243.252 Downloaded on 2014-12-03 to IPconditions used (e.g. exposure temperature, partial pressures of the reacting gas) adsorption / desorption of reacting gases and surface reaction are taking place. Then there are two possible options. If the adsorbed species are more or less covering the surface, this means all surface sites are occupied. Further adsorption is blocked resulting in selflimitation of the process. Self limited processing at low temperature is very beneficial for reliable and robust process technology.In the second case, the reacting gas is adsorbed on already occupied sites resulting in further gr...

Room Temperature Light Emission from Superatom-like Ge–Core/Si–Shell Quantum Dots

“…In addition, we also reported electroluminescence (EL) from the light-emitting diode structure with the 3-fold stacked Si-QDs with Ge core by application of continuous square-wave pulsed bias under cold light illumination, where EL signal was observed from the backside through the c-Si substrate caused by alternate electron/hole injection from the p-Si(100). In this work, we developed fabrication processes of the Si-QDs with Ge-core structure by means of a commercial reduced pressure (RP) CVD system [27][28][29][30] using SiH 4 and GeH 4 gases with H 2 carriers, which has been in practical use for the mass production of bipolar CMOS, for the fabrication of the Si-QDs with Ge-core on ultrathin SiO 2 layers, and evaluated their PL and EL characteristics without light illumination at room temperature.…”