| 摘要 |
PURPOSE:To relieve stress, and to obtain excellent characteristics and reliability by forming the surface in two layer structure of a plasma CVD-SiNx film and a CVD-SiO2 film and making total film thickness of said films satisfy the conditions of non- reflection to signal beams. CONSTITUTION:A buffer layer 7, an optical absorption layer 6 and a window layer 5 are formed onto a substrate 8 in succession, an SiO2 film 2 is attached onto the surface and a window is shaped, and a P type impurity is diffused to form a P<+> diffusion region 4. The SiO2 film is removed, an SiNx film 1 is shaped through a plasma CVD method, and an SiO2 film is laminated through a CVD method, thus obtaining protective films having double layer structure. Since films applying exact opposite stress are superposed in the surface protective films formed in this manner, tensile stress and compressive stress mutually deny, and stress applied to InP/InGaAs is made smaller than conventional devices by approximately one figure up to approximately 10<8>dyne/cm<2>. The titled device has an effect even in the aspect of preventing pin holes because of double layer structure, stress applied to a semiconductor is relieved largely, and the surface protective films having no pin hole are acquired, thus also improving reliability. The conditions of non-reflection are obtained at a wavelength of 1.55mum. |
