Stacked lateral double-diffused metal-oxide-semiconductor field effect transistor with enhanced depletion effect by surface substrate

A stacked lateral double-diffused metal-oxide-semiconductor field-effect transistor (LDMOS) with enhanced depletion effect by surface substrate is proposed (ST-LDMOS), which is compatible with the traditional CMOS processes. The new stacked structure is characterized by double substrates and surface dielectric trenches (SDT). The drift region is separated by the P-buried layer to form two vertically parallel devices. The doping concentration of the drift region is increased benefiting from the enhanced auxiliary depletion effect of the double substrates, leading to a lower specific on-resistance (R_on,sp). Multiple electric field peaks appear at the corners of the SDT, which improves the lateral electric field distribution and the breakdown voltage (BV). Compared to a conventional LDMOS (C-LDMOS), the BV in the ST-LDMOS increases from 259 V to 459 V, an improvement of 77.22%. The R_on,sp decreases from 39.62 mΩ·cm² to 23.24 mΩ·cm² and the Baliga's figure of merit (FOM) of is 9.07 MW/cm².