JPS5587475A - Production of semiconductor device - Google Patents

Abstract

PURPOSE: To prevent short-circuit caused by the electrode eliminating exposure of the shallow junctions to the surface by irradiating light into the hole doped with impurities to make the heat-affected section less in the depth than the impurity-doped layer before the electrode is applied thereon.

CONSTITUTION: An n-type epitaxial layer is provided on a p-type Si substrate on which an n⁺-type buried layer is arranged. Then, with a hole 16 made on an SiO₂ film 15, an n⁺-type emitter layer 17 is formed by the ion implantation. Then, a laser beam is pulse irradiated on the heat-affected part so as to make thereof less in the depth than the layer 17. This confines the thermal effect to the surface of the wafer so that heat can be stored in the layer under the SiO₂ film. As a result, there is little rediffusion of the impurity along the depth. With a rediffusion progressing along the interface of the film 15, the emitterbase junction on the surface moves to the outside from the end face of the hole 16. Thereafter, a hole for drawing the electrodes of the base and the emitter are provided and an Al electrode is mounted thereto. With such an arrangement, it is possible to prevent short-circuit between the emitters and bases due to the emitter electrode.

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