Patent ID: 7910964

Claim:
A semiconductor range-finding element, comprising: a semiconductor photoelectric conversion element comprising: a charge generation region of a first conductivity type, and a part of a surface buried region of a second conductivity type of an opposite conductivity type to the first conductivity type disposed on the charge generation region, configured to receive an optical pulse, which is reflected by a target sample, and configured to convert the optical pulse into signal charges in the charge generation region; first and second transfer gate electrodes configured to electrostatically control potentials of first and second transfer channels implemented by another part of the surface buried region adjacent to the part of the surface buried region directly over the charge generation region, through insulating films formed on the first and second transfer channels, respectively, and configured to alternately transfer the signal charges through the first and second transfer channels; and first and second floating drain regions configured to accumulate the signal charges transferred by the first and second transfer gate electrodes, sequentially and respectively, having the second conductivity type and a higher impurity concentration than the surface buried region, wherein, by sequentially applying pulse signals to the first and second transfer gate electrodes in synchronization with the optical pulse so as to operate the first and second transfer gate electrodes, a range to the target sample is measured, in accordance with a distribution ratio between the charges accumulated in the first and second floating drain regions.