Abstract: This invention provides a method or an auxiliary method to implement optimum variation lateral flux on a semiconductor surface. The method is to cover one or more thin films of high permittivity dielectric material on the semiconductor surface. The one or more films are capable of transmitting flux into or extracting flux from the semiconductor surface, or even to extract some flux from a part of the semiconductor surface and then transmit the flux to another part of the semiconductor surface. By using optimum variation lateral flux, not only can high-voltage lateral devices be made, but also an edge-termination technique for high-voltage vertical devices is provided. While the thin films can be used to prevent the occurrence of strong electric fields produced at the edges of some doped regions, these regions are used to compensate other doped regions with opposite doping and different location.

Abstract: A surface voltage sustaining structure for semiconductor device which includes at least one high-side high-voltage device, comprises at least two surface voltage sustaining regions, wherein a first surface voltage sustaining region is for sustaining a voltage drop from a high voltage terminal of the high-side high-voltage device to a floating voltage terminal of the high-side high-voltage device, and a second surface voltage sustaining region is for sustaining a voltage drop from said high voltage terminal or from said floating voltage terminal to the substrate. The potential of the floating-voltage terminal of the high-side high-voltage device can vary (float) from the potential of the substrate up to the potential of the high voltage terminal.

Abstract: A semiconductor power device wherein the reverse voltage across the p.sup.+ -regions(s) and the n.sup.+ -regions(s) is sustained by a composite buffer layer, shortly as CB-layer. The CB-layer contains two kinds of semiconductor regions with opposite types of conduction. These two kinds of regions are alternatively arranged, viewed from any cross-section parallel to the interface between the layer itself and the n.sup.+ (or p.sup.+)-region. Whereas the hitherto-used voltage sustaining layer contains only one kind of semiconductor with single type of conduction in the same sectional view. Design guidelines are also provided in this invention. The relation between the on-resistance in unit area Ron and the breakdown voltage V.sub.B of the CB-layer invented is Ron ocV.sub.B.sup.113 which represents a breakthrough to the conventional voltage sustaining layer, whereas the other performances of the power devices remain almost unchanged.