| 摘要 |
PURPOSE:To obtain the titled semiconductor device having excellent radioactive ray resistant property, low degree of variation in electric characteristics even in the environment in which radioactive rays are present, and a sufficiently long life by a method wherein two or more kinds of insulating films, having different trap density of electrons and holes, are laminated and formed into the insulating films to be used on the surface of a semiconductor substrate, and the insulating films having low trap density is arranged on the side of the semiconductor substrate. CONSTITUTION:First, an insulating film A1 is formed on a silicon semiconductor substrate 3 by performing a thermal oxidization method at a high temperature, and a deposited insulating film B2 is formed thereon by performing a chemical vapor deposition (CVD) method. The trap density of electrons and holes can be controlled using a diffusion and heat treatment, an ion-implantation method and the like. A flat band shift can be reduced by having the insulating film B2 in the thickness of 50% or more of the whole film thickness. Accordingly, the deterioration in efficiency caused by the irradiation of radioactive rays can be minimized. Also, the radioactive ray resisting property can be improved further by forming at least one of the two insulating films in the electron trap density of 3X10<17>/cm<2> or more.
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