Semiconductor range-finding element and solid-state imaging device

A solid-state imaging device including a plurality of pixels being arrayed, each of the pixels comprising:

• a semiconductor region of a first conductivity type;
• a light receiving surface-buried region of a second conductivity type buried in a part of an upper portion of the semiconductor region, to which a light reflected by a target sample is entered;
• a first charge-accumulation region of the second conductivity type buried in a part of the upper portion of the semiconductor region, a depth of a potential well of the first charge-accumulation region is deeper than the light receiving surface-buried region, and to which signal charges generated by the light are transferred from the light receiving surface-buried region;
• a first charge read-out region configured to receive the signal charges from the first charge-accumulation region;
• a first potential control means configured to control a potential of a channel formed in the upper portion of the semiconductor region between the light receiving surface-buried region and the first charge-accumulation region configured to transfer the signal charges from the light receiving surface-buried region to the first charge-accumulation region;
• a second potential control means configured to control a potential of a channel formed in the upper portion of the semiconductor region between the first charge-accumulation region and the first charge read-out region configured to transfer the signal charges from the first charge-accumulation region to the first charge read-out region;
• a first exhausting-drain region configured to extract the charges from the light receiving surface-buried region;
• and
• a third potential control means configured to control a potential of a channel formed in the upper portion of the semiconductor region between the light receiving surface-buried region and the first exhausting-drain region configured to transfer the signal charges from the light receiving surface-buried region to the first exhausting-drain region,
• wherein the signal charges dependent on a delay time of the reflected light are repeatedly transferred from the light receiving surface-buried region to the first charge-accumulation region so as to be accumulated as a first signal charge in the first charge-accumulation region in a first repetition period, all of the signal charges generated by the reflected light are repeatedly transferred from the light receiving surface-buried region so as to be accumulated as a second signal charge in the first charge-accumulation region in a second repetition period, and a ratio between total quantities of the accumulated first and second signal charges is calculated so as to measure a range to the target sample.