Optimization of the specific on-resistance of the COOLMOS™

The optimized values for the physical and geometrical parameters of the p- and n-regions used in the voltage-sustaining layer of the COOLMOS(TM)(1) are presented. Design of the parameters is aimed to produce the lowest specific on-resistance, R-on, for a given breakdown voltage, V-B. A new relationship between the R-on and V-B for the COOLMOS(TM) is developed as R-on = C.V-B(1.32), where the constant C is dependent on the cell dimension and pattern geometry. It is also found that by putting a thin layer of insulator between the p-region and its neighboring n-regions, the value of R-on can be further reduced. The possibility of incorporating the insulating layer may open up opportunities for practical implementation of the COOLMOS(TM) for volume production.