Jaegil Lee

A simulation study on novel field stop IGBTs using superjunction

Performing device simulation, a novel insulated gate bipolar transistor (IGBT) that employs the superjunction as well as field stop (FS), has been investigated. For a planar 1200-V IGBT, the novel superjunction FS IGBT demonstrates the remarkable device performance such as the ON-state voltage drop of 1.6 V and switching-off energy of 20 /spl mu/J/A at the collector current density of 100 A/cm/sup 2/, which is considered as the best tradeoff performance in its class. In addition, the impact of various design parameters on device performance has been explored, and a comprehensive analysis for understanding of the operating mechanism is presented, which will be of help for realizing the SJFS IGBTs with optimum design.

Investigation of Gate Oscillation of Power MOSFETs Induced by Avalanche Mode Operation

Serious gate oscillation of power MOSFETs under avalanche condition has been observed, degrading an avalanche withstanding capability. Using experiments as well as numerical simulation, it is shown that this gate oscillation in avalanche mode results from the impact ionized hole carrier accumulation on the surface under the gate oxide and the associated reciprocation between the gate of each unit cell with parasitic elements, which comes from a different phase of a gate capacitance according to a local avalanche breakdown. Experimental results also show that the devices with a poly-cut gate structure and a smaller chip size demonstrate strong immunity against the gate oscillation, which also verifies the new gate oscillation mechanism.