Further Study of the U-Shaped Channel SOI-LIGBT With Enhanced Current Density for High-Voltage Monolithic ICs

A high-voltage silicon-on-insulator lateral insulatedgate bipolar transistor (SOI-LIGBT) with U-shaped channels, which are composed of parallel channels and orthogonal channels for improving the current density (J(C)) and latch-up immunity, is proposed and studied intensively in this paper. By using the U-shaped channels, the electron injection from the emitter into the n-drift region is significantly enhanced, and the current density is improved. In addition, an analytical model is proposed, and it is indicated that J(C) can be improved as a (the angle between the parallel channel and the orthogonal channel) increases in a certain range. The hole current density distribution in the ON-state and the lattice temperature distribution in the short-circuit state of the proposed structure are also investigated. Increasing a is beneficial to alleviate the holes crowding beneath the n(+) emitter and suppress the temperature rise in the JFET region, which is favorable for increasing the latch-up voltage (VLP) and short-circuit withstand time (t(SC)). The experiments demonstrate that the U-shaped channel SOI-LIGBT fabricated with 0.5-mu m SOI technology exhibits a high current density (J(C)) of 305 A/cm(2) at V-CE = 3 V and V-GE = 5 V, and a low specific ON-resistance (R-ON.sp) of 0.984 Omega . mm(2) with breakdown voltage of 590 V. The improved latch-up voltage (V-LP) of 560 V and the short-circuit withstand time (t(SC)) of 5.1 mu s are obtained.