SOLID-STATE IMAGING DEVICE AND METHOD FOR MANUFACTURING THE SAME

摘要

Almost in the center of the light-receiving surface of an embedded photodiode (31), a floating diffusion (331) is formed and the gate electrode of a transfer transistor (32) is so disposed as to surround it. The impurity concentration (or depth) in the p+-type semiconductor region, n-type semiconductor region or p-type well region of the photodiode (31) is so inclined from the periphery toward the center as to form a potential gradient inclined downward from the periphery toward the center when applying a proper bias voltage to a pn junction. Photoelectric charges generated by receiving light are integrated in the center speedily according to the potential gradient. Since a maximum moving distance from the periphery of the photodiode (31) to the floating diffusion (331) is also short, the photoelectric charge can efficiently be collected even when a period for accumulating the photoelectric charges is short. Thus, detection sensitivity is improved by efficiently utilizing the photoelectric charges generated by the photodiode (31).