| 摘要 |
PURPOSE:To decrease the characteristic fluctuation to a practically negligible degree, by forming a film composed of such substance whose reflection coefficient to light is small and whose absorption coefficient to light is large onto the inner wall of a cap protecting semiconductor elements. CONSTITUTION:A film 40, for instance, composed of chromium oxide is adhered onto the inner surface of a cap 19 made of alumina type ceramics. A liquid composed of chromium powder and binder is spread over the ceramic inner wall. Then, said wall is burned in air to convert said liquid into a chromium oxide film, which is the film 40. Light 30 passing through a glass substrate 1 (1B is back surface) and transmitting through the inside of the cap 19 reaches the inner wall of the cap 19, however, the light 30 is almost absorbed here because the film 40 made of such substance as chromium oxide whose reflection coefficient to light is small and whose absorption coefficient to light is large is adhered onto the inner wall of the cap 19. Consequently, the rate of reaching a semiconductor tip 15 for the light which is transmitted inside the cap 19 is extremely decreased, so the characteristic fluctuation of the semiconductor tip 15 caused by the light can be decreased to a negligible degree. |
