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