Patent ID: 6472289
Filing Date: 2002-10-29
Classification: H01L,Y10S

Abstract:
A method of producing a dielectrically separated wafer having a plurality of dielectrically separated monocrystalline silicon islands mutually defined by a dielectrically separating oxide film, the method comprising:preparing a monocrystalline silicon wafer including an impurity of one conductivity type at a low concentration; forming a high concentration impurity layer including at high concentration an impurity of identical conductivity at a specified depth on the monocrystalline silicon wafer; forming dielecirically separating grooves deeper than said high concentration impurity layer; forming a dielectrically separating oxide film on each of surfaces of the dielectrically separating grooves and the silicon wafer; forming a polysilicon layer on the dielectrically separating oxide film; and forming a plurality of dielectrically separated silicon islands separated by said dielectric separating oxide film by grinding and polishing the silicon wafer from the undersurface, wherein the high concentration impurity layer is formed as a flat bottom layer of each dielectrically separated silicon island; and wherein said polysilicon layer is formed by forming first a seed low temperature CVD polysilicon layer by a low temperature CVD process and by forming second a high temperature CVD polysilicon layer by a high temperature CVD process.