In a CMOS image sensor, a plurality of photoelectric conversion elements serving as pixels is formed on the top face of a semiconductor substrate in an array shape. Transistors and wiring layers for reading the electric charges converted by the photoelectric conversion elements are also formed on the top face in which the photoelectric conversion elements are formed. Therefore, when light is incident, a ratio (aperture ratio) of light received by the photoelectric conversion elements for the top face of the semiconductor substrate falls largely below 100%. Thus, in the solid imaging device in which the transistors and the wiring layers are formed on the same face as the photoelectric conversion elements, there has been a problem of low use efficiency of incident light.
As a technology for increasing the aperture ratio greatly, there is a back side irradiation-type structure, in which the photoelectric conversion elements are formed on a back face opposite to the top face on which the transistors and the wiring layers are formed, and light is made to enter from the back face.