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 w as addressed in the absence and in the presence of arsine as the dopant pre cursor. The analysis includes a detailed modeling of the chemical mechanism for gas phase, plasma, and surface reactions embedded in a simplified tran sport description. The silane chemistry was taken almost entirely from the literature, while most of the arsine surface chemistry was inferred from ex perimental observations. The unknown rate constants were estimated through traditional thermochemical approaches. Both the thermal activated (low pres sure chemical vapor deposition, LPCVD) and the plasma assisted (PACVD) proc esses were examined to validate the theory on different literature trends. The dopant incorporation during codoping processes affects the semiconducto r growth rate, altering the kinetics of the deposition reactions. Here, thi s aspect was investigated by means of the charge-transfer adsorption theory that explains the modification of the surface reaction rate constants by m eans of the alteration of the Fermi level value of the solid due to the dop ant presence. This theory is also consistent with the typical long range ac tion of dopants on film properties. Particularly, the As codoping of silico n in the arsine/silane system was investigated here by confirming the gener al decrease of the growth rate in presence of n-type dopants. (C) 1999 The Electrochenical Society S0013-4651(98)03-006-7. All rights reserved.