150–200 V Split-Gate Trench Power MOSFETs with Multiple Epitaxial Layers

Abstract

A rating voltage of 150 and 200 V split-gate trench (SGT) power metal-oxide- semiconductor field-effect transistor (Power MOSFET) with different epitaxial layers was proposed and studied. In order to reduce the specific on-resistance (Ron,sp) of a 150 and 200 V SGT power MOSFET, we used a multiple epitaxies (EPIs) structure to design it and compared other single-EPI and double-EPIs devices based on the same fabrication process. We found that the bottom epitaxial (EPI) layer of a double-EPIs structure can be designed to support the breakdown voltage, and the top one can be adjusted to reduce the Ron,sp. Therefore, the double-EPIs device has more flexibility to achieve a lower Ron,sp than the single-EPI one. When the required voltage is over 100 V, the on-state resistance (Ron) of double-EPIs device is no longer satisfying our expectations. A triple-EPIs structure was designed and studied, to reduce its Ron, without sacrificing the breakdown voltage. We used an Integrated System Engineering-Technology Computer-Aided Design (ISE-TCAD) simulator to investigate and study the 150 V SGT power MOSFETs with different EPI structures, by modulating the thickness and resistivity of each EPI layer. The simulated Ron,sp of a 150 V triple-EPIs device is only 62% and 18.3% of that for the double-EPIs and single-EPI structure, respectively.

A novel split-gate trench MOSFET embedded with a high-k pillar for higher breakdown voltage

“…However, the counterpart of CSGT-MOS is located at the bottom trench. The peak electric field in the middle of the drift region is helpful to redistribute the electric field [12][13][14][15], and thus a more uniform electric field is formed in the HKP SGT-MOS and SSGT-MOS. It is clear that the electric field of HKP SGT-MOS decreases much more slowly than that of the SSGT-OS from the position of peak electric field to the N + substrate due to the reshape effect of the high-k pillar.…”

“…A self-biased SGT structure is proposed to further reduce its conduction losses [10,11], but the drawback is that its structure is complex and it costs additional chip area to generate the self-biased voltage. In addition, it has been reported that an SGT MOSFET with different epitaxial layers can significantly reduce the on-state resistance but requires a more complicated epitaxial process [12]. In contrast, the double split-gate structure exhibits a large BV by introducing an electric field peak in the middle of the drift region [13], in which the upper split gate is grounded, whereas the bottom split gate is kept floating.…”

A 100‐V trench power MOSFET with taper‐shielded gate and non‐uniform drift region doping profile

“…N on‐uniform d rift r egion (NDR) doping profiles have been widely adopted in SG‐MOSFETs to improve the trade‐off relationship between BV and specific ON‐resistance ( R ON,sp ) [7]. The doping gradient is an essential consideration for the NDR profile [8].…”