Kinetics of the decomposition of disilane molecules on a silicon growth surface in vacuum chemical epitaxy

Abstract

In the framework of the kinetic approach based on data of technological experiments, the range of characteristic rates of decomposition of disilane radical molecules adsorbed on the surface during the growth of a silicon layer is determined. The relationship between the rate of incorporation of silicon atoms into a growing crystal and the characteristic rate of pyrolysis of hydride molecules on the growing surface is established. The temperature dependences of the decomposition rate of disilane molecules exhibit an unusual activationless behavior in the growth temperature range. The form of the observed dependences is determined by the pyrolysis model, conditions of transferred of hydrogen from an adsorbed molecule onto the surface of the growing layer, being a function of the gas pressure and temperature in the reactor. It is demonstrated that the basic features of the behavior of the decomposition rate of disilane molecules are controlled by the specifics of the interaction of the silicon dihydride molecular beam with the growth surface under conditions of low and high degrees of bonding of hydrogen to free surface bonds. The temperature dependences are qualitatively described by a relation composed of two activation curves with different activation energies at low and high temperatures and preexponential factors depending on the surface coverage by hydrogen atoms.