Surface (lateral) voltage-sustaining region with an insulator film containing conductive particles

A surface voltage-sustaining region for a semiconductor device, said semiconductor device comprising a semiconductor substrate of a first conductivity type and a region having a highest voltage formed by a metal or a heavily doped semiconductor region of a second conductivity type in contact with said substrate and a region having a lowest voltage formed by a metal or a heavily doped semiconductor region of first conductivity type in contact with said substrate;

• said surface voltage-sustaining region is located at the top of said substrate, starting from said region having a highest voltage up to said region having a lowest voltage, wherein:
• said surface voltage-sustaining region contains at least one section of an insulator film containing conductive particles covering on a surface of said semiconductor;
• and said insulator film containing conductive particles has an average permittivity in a region larger than the dimension of the conductive particles;
• said average permittivity is named as macroscopic permittivity εI;
• said surface voltage-sustaining region transmits net average electric displacement of a first sign to said substrate everywhere when a reverse voltage close to the breakdown voltage is applied across said region having a highest voltage and said region having a lowest voltage;
• an net average electric displacement of a first sign starting from said region having a highest voltage with a value of qNBWpp decreases towards said region having a lowest voltage gradually or stepwisely, where q is the electron charge, NB is the impurity concentration of said substrate, Wpp is the depletion width under the breakdown voltage of a reverse-biased one-sided abrupt parallel plane junction formed by said substrate, wherein said net average electric displacement of a first sign means the value of the effective amount of fluxes of said electric displacement of a first sign in an area having a surface lateral dimension much smaller than Wpp but larger than the thickness of said surface voltage-sustaining region;
• and the thickness of said surface voltage-sustaining region means a sum of the thickness of said insulator film containing conductive particles in this area and the thickness of said semiconductor surface layer in this area, which is doped differently from said substrate;
• the sign of said net average electric displacement of a first sign means said net average electric displacement have the same sign as that of electric displacement generated by ionized impurities of a semiconductor of second conductivity type;
• said net average electric displacement of a first sign means the average electric displacement of a first sign minus the average electric displacement of a second sign which is opposite to the first sign;
• under the action of said net average electric displacement of a first sign, the surface lateral field in said surface voltage-sustaining region has its minimum value close to zero at said region having a highest voltage and increases its magnitude gradually or stepwisely when said position gets close to said region having a lowest voltage;
• under the condition that no conductor covered on said insulator film containing conductive particles, said net average electric displacement of a first sign generated by said insulator film containing conductive particles means, in a small section at said surface, a value which is a result of that the surface lateral field at a side nearest to said region having a highest voltage multiplied by a sheet capacitance of this side minus the surface lateral field at a side furthest to said region having a highest voltage multiplied by a sheet capacitance of the furthest side;
• said sheet capacitance is a result of a component parallel to said surface of semiconductor of the amount of the vector of fluxes of net average electric displacement of a first sign in said insulator film containing conductive particles divided by a component parallel to said surface of semiconductor of the electric field.