Influence of physical parameters on the quasi-saturation of a power SOI RF LDMOS

In this work, the influence of top silicon thickness T/sub si/, buried oxide thickness T/sub box/ and drift doping N/sub d/ on quasi-saturation in SOI RESURF LDMOS is investigated through extensive 2-D simulations. A physical insight on quasi-saturation in SOI structures with different top silicon thickness is provided. Furthermore the influence of Self-heating effect on quasi-saturation is also presented. The quasi-saturation current increases as the decrease in top silicon thickness up to T/sub si/ 1.0 /spl mu/m with the same drift dose. Beyond this value quasi-saturation current remains unchanged with T/sub si/. The analysis shows that the saturation of carrier velocity in the drift neutral region is the main cause for higher quasi-saturation current in SOI structures with T/sub si/ less than 1.0 /spl mu/m. Under optimum RESURF condition, reducing buried oxide increases the quasi-saturation current dramatically.