Study Of Trench Type High Voltage Lateral MOSFET With Low Power Consumption

As the key devices of the power integrated circuits(PICs), lateral double-diffused metal-oxide-semiconductor field effect transistors(LDMOSFET) have developed toward the direction of high breakdown voltage(BV) and low specific on-resistance(Ron,sp) for several decade years. A long and lightly doped drift region is needed to achieve a high BV, but it results in a high Ron,sp. The contradictory relationship between BV and Ron,sp is the “Silicon Limit”, which is a major issue in the semiconductor industry. In order to alleviate the issue, we proposed three trench LDMOSFETs with high breakdown voltage over 600 V in this paper.(1) A high voltage trench LDMOSFET with a buried P-layer(BP TLDMOS) is proposed. Simulation results show that the BP TLDMOS can achieve the BV of 685 V and the Ron,sp of 44.5m??cm2 with the trench of 9μm width and 18μm depth. The BP TLDMOS improves BV by 67% and reduces Ron,sp by 91% compared with the conventional trench LDMOS(C-TLDMOS) at the same cell pitch.(2) A high voltage trench LDMOSFET with a variable-k dielectric trench(VK TLDMOS) is proposed. Simulated results indicate that the VK TLDMOS can obtain the BV of 658 V and the Ron,sp of 25.1m??cm2 with the variable-k trench of 6μm width and 18μm depth. Compared with the conventional P-TLDMOS(the LDMOS with a SiO2-filled dielectric trench in the drifg region and a P-pillar next to the trench) at the same cell pitch, the BV of VK TLDMOS improves by 25.8% and the Ron,sp of VK TLDMOS only increases by 3.7%.(3)A high voltage trench LDMOSFET with a variable-k dielectric trench and a buried P-layer(VKBP TLDMOS) is proposed. The simulation results show that it can achieve the BV of 703 V and the Ron,sp of 42.1m??cm2 with the trench of 7μm width and 18μm depth.