The Kinetics of Silicon Deposition on Silicon by Pyrolysis of Silane: A Mass Spectrometric Investigation by Molecular Beam Sampling

Abstract

The kinetics of silane pyrolysis on a silicon (111) surface has been investigated mass spectrometrically by molecular beam sampling over the silane pressure range Torr and specimen temperature range 20°–1200°C. Silane decomposition was found to occur by the mechanism where both the amount of adsorbed silane and decomposition rate depend linearly on silane pressure. The activation energy for decomposition was and the surface reaction efficiency (α) was found to obey the equation At silane pressures , small quantities of disilane formed by the bimolecular surface reaction were detected with an activation energy for production of .Measurements of silicon growth rate as a function of silane pressure supported the first‐order mechanism for decomposition. The condensation coefficient (σ) of silicon adatoms, determined from measurements of the silicon growth rate as a function of temperature and the surface reaction efficiency, was found to be less than 0.3 over the entire temperature range 700°–1200°C, indicating that the majority of silicon adatoms were desorbed. This behavior was accounted for on the basis of a step flow model for silicon growth and an activation energy for surface diffusion of derived. Addition of arsine to the silane was found to inhibit silane pyrolysis. The measurements suggest an activation energy of for desorption of arsenic adsorbed on the silicon (111) surface. Additions of more than 1% diborane to the silane, on the other hand, resulted in a significant increase in silane reaction efficiency.