A Bootstrap Diode Emulator Integration to 600 V N-Type Epitaxial Platform for High Voltage Gate Driver IC

An integrated bootstrap diode emulator is experimentally investigated, including a high voltage (HV) junction field effect transistor (JFET) with adjustable pinch-off voltage ( $\text{V}_{{\mathrm {P}}}$ ) and a medium voltage (MV) diode. It features substrate leakage current suppression, and it can be integrated to 600 V N-type epitaxial (N-epi) Bipolar-CMOS-DMOS (BCD) technology. The HV JFET is formed in a part of the high voltage isolation region and the MV diode is formed outside of the high voltage isolation region. In HV JFET, the extending P-type buried layer (PBL) is introduced as the back gate to adjust $\text{V}_{{\mathrm {P}}}$ of JFET. Since JFET is easy to pinch-off, and $\text{V}_{{\mathrm {P}}}$ of JFET is much lower than breakdown voltage (BV) of MV diode, the bootstrap diode emulator can obtain a high BV of 970 V at block mode. Moreover, BV of MV diode depends on the thickness and doping concentration of N-epi rather than the doping concentration of N-type buried layer (NBL). Thus, the highly doped NBL layer can be introduced in the junction of N-epi/P-sub to further suppress the substrate leakage current at conduction mode. Besides, due to the fact that HV JFET is a majority carrier device, the equivalent reverse recovery characteristic of the bootstrap diode emulator is also competitively, and the equivalent reverse recovery process is also qualitatively analyzed.