Solid-state image pickup device and method for manufacturing solid-state image pickup device

A method for manufacturing a solid-state image pickup device that includes a substrate including a photoelectric conversion unit and a waveguide arranged on the substrate, the waveguide corresponding to the photoelectric conversion unit and including a core and a cladding, includes a first step and a second step, in which in the first step and the second step, a member to be formed into the core is formed in an opening in the cladding by high-density plasma-enhanced chemical vapor deposition, and in which after the first step, in the second step, the member to be formed into the core is formed by the high-density plasma-enhanced chemical vapor deposition under conditions in which the ratio of a radio-frequency power on the back face side of the substrate to a radio-frequency power on the front face side of the substrate is higher than that in the first step.