JPS5522811A - Manufacturing of semiconductor apparatus - Google Patents

Abstract

PURPOSE: To eliminate the formation of heat strain and, at the same time, avoid the necessity of gradual heating and gradual cooling when heat-treating semiconductor element regions provided on a sapphire substrate by irradiating interfaces among the regions with laser rays from the under surface of the substrate.

CONSTITUTION: An N type Si monocrystal layer 2 is gas phase-grown on a sapphire substrate 1, and a SiO₂ film 3 and a Si₃N₄ film 4 are laminated and coated on the entire surface of the substrate 1. A double mask for the films 3 and 4 is formed by etching, and a layer 2 at the both ends of the mask is converted into a SiO₂ film 5 reaching the substrate 1. Thereafter, the films 4 and 2 are converted into a thin SiO₂ film 6, through which P type impurity ions are injected to provide a P type region 7 for controlling the voltage. Then a polycrystal Si layer 8 is grown on the whole surface and etched to make only a gate electrode region 80 remain therein, and P type impurity ions are again injected to change the region 80 into P type and, at the same time, to form P type regions 21 and 22. Thereafter, irradiating from the back surface with a scanning laser light, these regions are heat-treated.

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