Analysis and design of vertical N-channel IGBT

Abstract

Steady-state operation of a vertical n-channel IGBT has been investigated by means of analytical models and simulations. P-I-N diode, bipolar transistor and MOSFET models have been applied to gain physical insight into the structure. A design approach has been formulated for blocking voltage capability, forward current density, forward voltage drop and latching current density, which is crucial to device operation. Based on this approach, a 1000 V, 20 A n-channel vertical IGBT has been designed. Various structural parameters such as W, L/sub n//sup +/, L/sub C/, L/sub CH/ and process parameters X/sub j/, /spl rho//spl square/, t/sub ox/, t/sub poly/, impurity concentration, etc. have been computed. Trade-offs curves for J/sub c/-V/sub a/, V/sub F/-d/L/sub a/, J/sub CL/-L/sub n//sup +/, L/sub CL/-C/sub BS/ have been obtained from design and simulation. The calculated values of various design parameters are N/sub d/=2.35/spl times/10/sup 14/ atoms/cm/sup 3/, W=100 /spl mu/m, p-base surface concentration=1/spl times/10/sup 17/ atoms/cm/sup 3/, p-base depth=4 /spl mu/m, L/sub n//sup +/=6 /spl mu/m, n/sup +/ depth=1 /spl mu/m, L/sub CH/=2 /spl mu/m and t/sub ox/=9000 /spl Aring/, with poly-Si gate. Unit cell size is 40 /spl mu/m/spl times/40 /spl mu/m. The results presented provide guidelines for designing high-voltage and high-current bipolar transistors for various applications.