The optimum design of a vertical power MOSFET with thick drain oxide is described, taking into account such dc characteristics as the on‐resistance and breakdown voltage. Introducing the empirical ideality of the edge‐termination which determines the breakdown voltage of the device, the optimum doping density and thickness of the epitaxial layer have been determined to minimize the on‐resistance. Using two‐dimensional simulation to evaluate the optimum design of the device, the thickness of the drain oxide and the relationship between the layout pitch and the product of on‐resistance and active area have been determined. As a result, the following conclusions have been obtained. 1) Based on the ideality for the edge‐termination, the optimum combination between the thickness and the doping density of the epitaxial layer can be determined. 2) The optimum layout pitch depends on the decrease in the electron concentration in the accumulation layer at the drain surface and the parasitic JEET effect. 3) The optimum layout pitch decreases as the thickness of the drain oxide increases. Finally, the design of a vertical MOSFET with a breakdown voltage of 500 V will be described.
|Number of pages||12|
|Journal||Electronics and Communications in Japan (Part II: Electronics)|
|State||Published - 1 Jan 1987|