J. Phys. IV France 03 (1993) C3-51-C3-58
Low pressure silicon selective epitaxial growth and its thermodynamic considerationsL. YE, B.M. ARMSTRONG and H.S. GAMBLE
Institute of Advanced Microelectronics, Department of Electrical and Electronic Engineering The Queen's University of Belfast, Belfast BT9 5AH, United Kingdom
In a rapid thermal processing reactor QUPLAS II, full selective epitaxial growth of silicon has been obtained using DCS in H2 without addition of HCl. This is mainly achieved by reducing total process pressure down to the millibar regime. Selectivity can also be controlled by reducing DCS gas flow rate ; however, the growth rate is greatly reduced. Process temperature has, on the other hand, a minor effect on selectivity control. The selective epitaxial growth (SEG) occurs under conditions of near thermodynamic equilibrium. Thus equilibrium partial pressures of the predominant species in the Si-H-Cl system have been calculated to give an insight into the experimental results. The availability of HCl species relative to silicon containing species in the gas phase, PHCl/PSi, has shown why no external HCl is required, for depositions in millibar regime or low DCS flow rate, to obtain full selectivity. While reaction system is near-equilibrium, the reposition of Cl, dissociated from Si containing species, into HCl species, plays an important role in determining the system etching function.
© EDP Sciences 1993