Cushman Darby & Cushman IP Group of Pillsbury Madison & Sutro LLP
Method for manufacturing a photo-sensor
 A photoelectric transfer device having a light receiving element and a signal processing circuit are formed in a semiconductor substrate, a silicon oxide film is formed on the light receiving element, a first aluminum thin film is deposited on the silicon substrate, and the first aluminum thin film is patterned to make a wire connected with the signal processing circuit and a protective film placed on the silicon oxide film. Thereafter, an inter-layer insulating film is deposited on the silicon substrate while covering the protective film, a portion of the inter-layer insulating film placed on the protective film is etched and removed, a second aluminum thin film is deposited on the inter-layer insulating film and the protective film, and a portion of the second aluminum thin film placed on the protective film and the protective film are successively etched and removed. Because the inter-layer insulating film placed above the light receiving element is removed, an insulating film placed on the light receiving element is not thinned, so that sensitivity of the photoelectric transfer device can be improved. Also, because the protective film is arranged on the silicon oxide film when the portion of the inter-layer insulating film is etched, the silicon oxide film is not etched, so that a film thickness of the silicon oxide film can be correctly set to a desired value. 
Denso Corporation
H
H01L
inventional
Inao Yasutoshi Keijiro
Toyoda Suzuki Inoue