Effect of fluorine-doping on the dielectric strength of thin SiO ₂ films formed by plasma-enhanced chemical vapor deposition

Fluorine-doped thin SiO₂ films were formed by plasma-enhanced chemical vapor deposition of tetraethoxysilane and CF ₄ and the intrinsic dielectric strength was measured with a self-healing breakdown technique by applying short-duration voltage pulses. The vacuum-ultraviolet absorption and photoluminescence were observed using synchrotron radiation as a photon source. From the decay profile of luminescence, the microscopic structure of the film was estimated. In the case of the film containing a higher amount of fluorine, the randomness in microscopic structure is smaller and the dielectric strength is higher. From this, it is considered that the higher dielectric strength comes from the relaxation of the structural distortion in the film