COLOR IDENTIFYING ELEMENT

摘要

PURPOSE:To prevent deterioration in spectral characteristics of an element, by providing an interference filter with the upper most layer of a dielectric film as protective layer comprising ZnS. CONSTITUTION:A P<+>-Si area 2 is formed on an n-Si substrate 1 and composes an Si photodiode (light receiving element). A photocurrent of the light receiving element is drawn from between an Au electrode 8 and Al electrode 4 provided on the undersurface of the substrate 1. An interference filter is formed on a light receiving surface of the light receiving element. This interference filter is provided with a protective film (ZnS) 7 placed on a multilayer structure alternately laminated with a semi-transparent metal film (Ag) 5 and a low- refractive-index dielectric film (MgF2)6. Then, the first fifth layers of Ag films are designed to obtain a spectral transmission factor as target and ZnS of the uppermost layer is made so sufficiently thin as not to optically affect the spectral transmission factor of the first filth lower but sufficiently thick to accomplish a function as protective film. This can prevent deterioration in the spectral characteristic of the element.