Silcon nitride for backside passivation of silicon wafer

Silicon nitride(sin) thin films were prepared on P type Cz silicon wafer by PECVD.The research on rear surface passivation effect of the non-diffused and diffused covered on both sides with different thickness sin films and the lifetime varied after firing.It was found through QSSPCD that when the sin film were less than 17 nm and exceeded 26 nm,the rear surface passivation effect reduced and kept accord,respectively.The lifetime of nondiffused reduced in the different thickness film condition after firing,but the lifetime of diffused improved before and after firing.The results above indicated that it was beneficial to improve material lifetime by using sin as passivation films which could be chosen between 26～75 nm.