Novel SOI LDMOS Without RESURF Effect by Flexible Substrate for Flexible Electronic Systems

In this article, laterally diffused MOS (LDMOS) combined with flexible substrate polydimethylsiloxane (PDMS) which can be used in flexible electronic system is described. The flexible substrate has insulation characteristics, which makes the original substrate float; thus, the substrate electrode and reduce surface electric field (RESURF) technology are missing. The simulation results show that the breakdown voltage (BV) of LDMOS combined with PDMS decreases by 23.3%. Considering that most flexible electronic systems require thin functional layers to achieve portability, the use of SOI LDMOS can achieve better performance on thinner substrates. Then, through simulation, the flexible substrate will reduce the BV of the SOI LDMOS by 17.4%, and combined with experiments and tests, it is verified that the flexible substrate will indeed reduce the BV of the SOI LDMOS by 15%, which is basically consistent with the simulation results. But there is no obvious effect on the specific ON-resistance ( ${R} _{ \mathrm{ON},\text {sp}}$ ). For the phenomenon of substrate floating, a new structure named surface electrodes trench drift region SOI LDMOS (SETD SOI LDMOS) is proposed. After optimizing the simulation, compared with conventional SOI LDMOS, the SOI LDMOS combined with the flexible substrate can achieve a 57.54% increase in the BV while reducing ${R} _{ \mathrm{ON},\text {sp}}$ by 11%.