Abstract

The effects of hydrogen content on the optical, chemical, structural, and electric conductivity properties of the laser chemical vapor-deposition (L-CVD) thin films of an amorphous silicon-hydrogen alloy (a-Si:H) are investigated herein. In the L-CVD technique an excimer laser operating ArF transition provides 193-nm radiation. The laser light, having 18-W maximum average power, illuminates the substrate surface under the angle of incidence ψ_i, ranging from 0 to 90°. The feedstock gas disilane, Si₂H₆, and carrier gas, He, introduce into the preevacuated (~10⁻⁶-Torr) deposition chamber. The flow rate ratio of Si₂H₆/He and working pressure were 1₁₀ and 10 Torr, respectively. Disilane absorbs energy from laser light producing free radicals following photodissociation. The free radicals condensate on the substrate surface to form a-Si:H films. The deposition rate increases with increasing angle of incidence and decreases with increasing laser power. The typical deposition rate and thickness of the L-CVD a-Si:H films were 13 nm/min and 200 nm, respectively. Substrate temperature T_s ranging from 35 to 350°C was used to control hydrogen content in the films.

© 1986 Optical Society of America