An innovative TCAD simulated UHV-PLDMOS device with improved HTRB performance

Abstract

This study proposed an innovative TCAD simulated ultra-high voltage p-type laterally diffused metal oxide semiconductor device structure with metal II field plate optimization (metal II is the second metal used on top of metal I with 10 000 Å Oxide dielectric in between as shown in figure 1), which could improve high-temperature reverse-bias (HTRB) performance. By optimizing the metal II field plate position, the exposed area could be minimized, and furthermore, after using the passivation layer of oxide-(a-Si: H)-oxide-(a-Si: H)-nitride after stress, the hole trap concentration was much lower than that in the silicon nitride and silicon dioxide passivation region because of the low mobility of (a-Si: H), which was 1 cm 2 v −1 s −1 . The new passivation layer maintained the original p-drift reduced surface field (RESURF) doping profile and exhibited less degradation in terms of losing positive ions from the p RESURF channel crossing oxide and entering the traps. The five layers exhibited fewer traps; therefore, the degradation was improved. The reliability of the device could be increased by changing the doping concentration of the drift region according to the RESURF principle. In addition, this study compared two passivation layers of (oxide-silicon nitride) and five passivation layers of oxide-(a-Si: H)-oxide-(a-Si: H)-nitride.