Diffusion of phosphorus in silicon oxide film

摘要: The system P2O5 (vapor), SiO2 (thin film) and single-crystal silicon has been investigated by solid-state-diffusion techniques. p-type underneath the oxide film was used as a “phosphorus detector”. A rapid complete chemical reaction apparently takes place between diffusant, phosphorus or oxide, forming glass (or compound) of unknown composition PxSiyOz at glass/silicon interface. sharp boundary is found unreacted SiO2. results indicate that growth limited diffusion species in with very little no diffusant left to diffuse dioxide after this compound follows parabolic law experimentally given xm2tm = 1.7 × 10−7exp(−l.46kTm) cm2/sec xm√ (tm)= 250 exp(−l.462kTm) μ√ (hr) over temperature range 900–1250°C. Here xm thickness glass, tm time Tm diffus ion (°K). subscript m denotes condition masking against phosphorus, i.e. n−p junction formed. Diffusion experiments which failed mask only partially masked P2O5, x02td smaller than value for xm2tm, where x0 original td time, were also performed could be interpreted using two-boundary model. In case, diffuses through coefficient, D1, followed thep-type higher D2, form n−pjunction glass. segregation coefficient small. transition region partial well defined occurs layer < 500 A. Such change represents models discussed above : model masking.