ArF excimer laser-enhanced photochemical vapor deposition of epitaxial Si from Si₂H₆: a simple growth kinetic model

Abstract

Photolysis of Si₂H₆ using 193 nm radiation from an ArF excimer laser has been used to deposit homoepitaxial Si films in the temperature range of 250 to 350°C. Photolytic decomposition of Si₂H₆ generates growth precursors which adsorb on to a hydrogenated Si surface. A growth kinetic model is proposed based on single-photon 193 nm absorption by Si₂H₆, and chemical reaction of the photofragments as they diffuse to the sub-strate surface. With the laser beam positioned parallel to the Si substrate, the deposi-tion yield of solid Si from photo-excited Si2H6 is estimated to be 0.20 ± 0.04. Growth rates vary linearly with laser intensity and Si₂H₆ partial pressure over a range of 1-15 mJ/cm². pulse and 5-40 mTorr, respectively, and epitaxial films are deposited when laser intensity and Si₂H₆ partial pressure conditions are such that the initial photofragment concentration is less than ~10¹³ cm^-3.