A solid-state image pickup device, including: a plurality of pixels; a separation structure provided along a boundary line adjacent to the plurality of pixels; the separation structure includes a groove provided from a back surface of the semiconductor substrate to a depth corresponding to a wavelength, the groove being positioned along the boundary line, a first separation layer provided in the groove, and a second separation layer provided above the first separation layer and corresponding to the boundary line, the second separation layer being connected to the first separation layer; and methods including the same.