SEMICONDUCTOR DEVICE AND MANUFACTURE THEREOF

摘要

PROBLEM TO BE SOLVED: To enable a protective element to be formed by a method wherein a semiconductor layer whose conductivity type is opposite to that of the primary surface of a semiconductor substrate is formed on a gap on the primary surface of the substrate where an insulating film is formed in a prescribed region. SOLUTION: Diodes serving as protective elements are provided separate from each other by a gap in a region where filed insulating films 3 are formed. Diodes or N+-type polycrystalline silicon layers 17a and P-type polycrystalline silicon layers 17b are alternately arranged on field insulating films 3 which surround the wirings of gate 4. A punch-through structure where rectangular rings 16 of floating P-type diffusion layers are arranged around a source wiring which serves as the terminal of a chip, and a depletion layer extends outwards from the inner rings before an avalanche breakdown starts with an increase in an applied voltage is provided. By this setup, a parasitic MISFET is prevented from being formed, a semiconductor element of this constitution can be prevented from deteriorating in withstand voltage, a P-type layer usually provided under an insulating film can be dispensed with, and manufacturing processes can be reduced in number.