Journal of the Electrochemical Society, Vol.146, No.1, 103-110, 1999
Kinetic modeling and dopant effect on silicon deposition - Low pressure and plasma assisted chemical vapor deposition
The kinetics of silicon deposition from silane in low pressure conditions was addressed in the absence and in the presence of arsine as the dopant precursor. The analysis includes a detailed modeling of the chemical mechanism for gas phase, plasma, and surface reactions embedded in a simplified transport description. The silane chemistry was taken almost entirely from the literature, while most of the arsine surface chemistry was inferred from experimental observations. The unknown rate constants were estimated through traditional thermochemical approaches. Both the thermal activated (low pressure chemical vapor deposition, LPCVD) and the plasma assisted (PACVD) processes were examined to validate the theory on different literature trends. The dopant incorporation during codoping processes affects the semiconductor growth rate, altering the kinetics of the deposition reactions. Here, this aspect was investigated by means of the charge-transfer adsorption theory that explains the modification of the surface reaction rate constants by means of the alteration of the Fermi level value of the solid due to the dopant presence. This theory is also consistent with the typical long range action of dopants on film properties. Particularly, the As codoping of silicon in the arsine/silane system was investigated here by confirming the general decrease of the growth rate in presence of n-type dopants.
Keywords:DOPED EPITAXIAL SILICON;LOW-TEMPERATURES;POLYCRYSTALLINESILICON;GROWTH-RATE;ENHANCED DEPOSITION;MATHEMATICAL-MODEL;SURFACE-REACTIONS;SILANE;REACTOR;SIH4