Effects of P+-Layer Emitter Profile of Power Diode Structure on Forward Voltage

Abstract

The increase in the diameter of silicon wafers amplifies the disadvantages of the diffusion method of power device manufacture. High temperature and the lengthiness of the diffusion process, geometric and concentration inhomogeneity of doping material distribution, as well as defects of doped layers lead to increased voltage drop values for forward current. Lower values of forward voltage drops are shown for silicon power diodes with anodic junction obtained by thermomigration of liquid zones, compared to conventional alternatives. It has been found that this result is associated with two factors. Firstly, the thermomigration method allows to optimize the base layer thickness of the device, as well as to obtain a more prominent doping material distribution in the emitter region. The advantages of thermomigration have been found to be amplified by the use of large-diameter silicon wafers.