Performance trade-off for the Insulated Gate Bipolar Transistor: Buffer layer versus base lifetime reduction

Abstract

A one-dimensional analytic model for the Insulated Gate Bipolar Transistor (IGBT) which includes a high-doped buffer layer in the low-doped bipolar transistor base is developed. The model is used to perform a theoreti cal trade-off study between IGBTs with and without the buffer layer. The study is performed for devices of equal breakdown voltages, and the critical parameters chosen to "trade-off" are turn-off switching energy loss (related to turn-off time) and on-state voltage, both at a given current. In this study, as in reality, the two crit ical parameters are varied by: 1) adjusting the doping concentration and thickness of a buffer layer included as part of the bipolar transistor base, 2) adjusting the lifetime in the lowly doped bipolar transistor base with no buffer layer included, or by 3) a combination of 1) and 2). The results of the model predict that for equal breakdown voltages, an optimized device with a buffer layer has less switching energy loss for a given on-state voltage than an optimized device with no buffer layer. 27 u.s. Govemrnent work not proteCted by U.S. copyright.

An improved understanding for the transient operation of the power insulated gate bipolar transistor (IGBT)

“…The time-dependent ambipolar diffusion equation is given by: (4) a'sp sp 1 asp -L2 + --, D dt _ -and is valid for devices in which IT is independent of position such as the IGBT where the base current is introduced at the collector end of the base. This equation is solved for the boundary conditions and initial condition to determine the distribution of excess carriers in the base.…”

Physics‐based model of LPT CSTBT including MOS‐side two‐dimensional effects

“…t H is the excess carrier lifetime in LPT buffer layer. Solving ADE (11) with the boundary conditions of p(0, t) = P H0 and p(W H , t) = P HW , the excess carrier concentration in steady state is [14,32] dp where P H0 , P HW are excess hole concentrations at x* = 0 and x* = W H , respectively, as shown in Fig. 1.…”

“…The gate collector displacement current due to the variation of Miller capacitance is [9] I cg = C gc dV d dt − dV ge dt (32) where…”

“…Solving ADE (11) with the boundary conditions of p (0, t ) = P H 0 and p ( W H , t ) = P HW , the excess carrier concentration in steady state is [14, 32] where P H 0 , P HW are excess hole concentrations at x * = 0 and x * = W H , respectively, as shown in Fig. 1.…”

Compact Modeling of IGBT Charging/Discharging for Accurate Switching Prediction

“…Further, the highly resistive base region can sustain extremely high applied voltages. There are several compact models developed previously by different research groups, where the modeling focuses mainly on the functionally-active intrinsic part of the IGBT [13]- [17]. The IGBT modeling causes often numerical instabilities during circuit simulation, resulting from steep local-electric-field increases, which occur during switching predominantly within the base region.…”