JPS6465866A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To decrease the loss due to reflection so as to improve a detecting element in prop erty by a method wherein a film, which is composed of a film that is on a substrate side and comprises SiO2 as a main component and a silicon oxynitride film that increases in a SiN component starting from lowest layer of SiO2 to uppermost layer and overlaps the former layer, is made to cover a photodetector section. CONSTITUTION:A FET composed of photodiodes which consist of a p layer 2, a p-type source/ drain 3, a SiO2 film 4, and a gate 5, and a capacitor which is composed of the p layer 2 and a wiring 7 that are opposed to each other interposing the SiO2 film 4 between them are integrated on the surface of an N-type Si substrate 1, and a required silicon oxynitride film 8 is coated on the Al wiring 7. A prescribed amount of SiH4 and N2O is made to flow in a reaction vessel which is kept at a pressure of 1Torr, and NH3 is supplied into the vessel as it increases in amount at a specified rate per minute starting from zero, and a RF power is impressed, so that a silicon oxynitride film 8 is deposited in such a manner that silicon nitride contained in the film 8 starts to increase gradually from the lowest layer toward the upperpost layer. The film 8 decreases gradually in refractive index starting from the top, is remarkably lower than a silicon nitride film in refractive index, and decreases in reflectivity at the interface of the lowest layer and at the interface of it with air as well, and thus a photodetective property is made to be improved.