Arsenic Doping of Chemical Vapor Deposited Polycrystalline Silicon Using SiH4 ‐ H 2 ‐ AsH3 Gas System

Abstract

The arsenic concentration in polycrystalline silicon (poly‐Si) deposited under various deposition conditions in the deposition temperature range 670°–760°C using gas system has been determined by neutron activation analysis. From the experimental results, it was found that increases with decreasing deposition temperature and with increasing partial pressure of in the gas introduced into the reactor , and that for lower region, decreases with decreasing gas velocity and with increasing deposition rate, and for higher region, is independent of gas velocity and deposition rate. From the analyses of the experimental data, it was suggested that (i) for lower region, is limited by the diffusion of As‐containing species, such as As molecule, molecule, and molecule, in the stagnant layer formed by gas stream, and for higher region, is controlled by the surface reaction; (ii) monatomic As existing at wafer surface is incorporated in poly‐Si in accordance with Henry's law; (iii) the transfer coefficient of As atoms in gas phase increases slightly with increasing deposition temperature and gas velocity; (iv) the segregation coefficient of monatomic As between gas phase and poly‐Si is approximated by ; (v) the energy of As‐Si bond is 44.5 kcal/mole.