Optical detection element and solid-state image pickup device
A radiation tolerant optical detection element includes: a p-type base-body region; a gate insulating film provided on an upper surface of the base-body region; an n-type buried charge-generation region buried in an upper portion of the base-body region; an n-type charge-readout region buried in an upper portion of the base-body region on the inner-contour side of the buried charge-generation region; an n-type reset-drain region buried on the inner-contour side of the charge-readout region; a transparent electrode provided on the gate insulating film above the buried charge-generation region; and a reset-gate electrode provided on a portion of the gate insulating film between the charge-readout region and the reset-drain region.
1. An optical detection element comprising:
a base-body region made of a semiconductor having a first conductivity type;
a gate insulating film contacted with an upper surface of the base-body region;
a buried charge-generation region of a second conductivity type buried with an annular form in an upper portion of the base-body region, being contacted with the gate insulating film;
a charge-readout region of the second conductivity type having a higher impurity concentration than the buried charge-generation region, buried with an annular form in the upper portion of the base-body region at a position on an inner-contour side of the buried charge-generation region;
a reset-drain region of the second conductivity type having a higher impurity concentration than the buried charge-generation region, buried in the upper portion of the base-body region at a position on the inner-contour side of the charge-readout region, being separated from the charge-readout region;
a transparent electrode provided in an annular form on the gate insulating film, allocated above the buried charge-generation region; and
a reset-gate electrode stacked on the gate insulating film, allocated above the base-body region between the charge-readout region and the reset-drain region,
wherein a surface potential in the surface portion of the buried charge-generation region is pinned by charges of minority carriers in the buried charge-generation region.
2. The optical detection element of claim 1 , wherein when a voltage is applied to the reset-gate electrode, the charges accumulated in the charge-readout region are exhausted to the reset-drain region so as to reset the charge-readout region.
3. The optical detection element of claim 1 , wherein the charge-readout region is in contact with the buried charge-generation region.
4. The optical detection element of claim 1 , wherein
the charge-readout region is separated from the buried charge-generation region,
a transfer-gate electrode is further stacked on the gate insulating film, allocated above the base-body region between the buried charge-generation region and the charge-readout region, and
when a voltage is applied to the transfer-gate electrode, signal charges are transferred from the buried charge-generation region to the charge-readout region.
5. A solid-state image pickup device in which a plurality of pixels is arranged, each pixel comprising:
a base-body region made of a semiconductor having a first conductivity type;
a gate insulating film contacted with an upper surface of the base-body region;
a buried charge-generation region of a second conductivity type buried with an annular form in an upper portion of the base-body region, being contacted with the gate insulating film;
a charge-readout region of the second conductivity type having a higher impurity concentration than the buried charge-generation region, buried with an annular form in the upper portion of the base-body region at a position on an inner-contour side of the buried charge-generation region;
a reset-drain region of the second conductivity type having a higher impurity concentration than the buried charge-generation region, buried in the upper portion of the base-body region at a position on the inner-contour side of the charge-readout region, being separated from the charge-readout region;
a transparent electrode provided in an annular form on a gate insulating film, allocated above the buried charge-generation region; and
a reset-gate electrode stacked on the gate insulating film, allocated above the base-body region between the charge-readout region and the reset-drain region,
wherein in each of the plurality of arranged pixels, a surface potential in the surface portion of the buried charge-generation region is pinned by charges of minority carriers in the buried charge-generation region.
6. The solid-state image pickup device of claim 5 , wherein in each of the pixels, when a voltage is applied to each of the reset-gate electrodes, the charges accumulated in each of the charge-readout regions are exhausted to the corresponding reset-drain region to reset the charge-readout region.
7. The solid-state image pickup device of claim 5 , wherein the charge-readout region is in contact with the buried charge-generation region of each of the pixels.
8. The solid-state image pickup device of claim 5 , wherein
in each of the pixels, the charge-readout region is separated from the buried charge-generation region,
a transfer-gate electrode is further stacked on the gate insulating film, allocated above the base-body region between the buried charge-generation region and the charge-readout region of each of the pixels, and
in each of the pixels, when a voltage is applied to the transfer-gate electrode, signal charges are transferred from the buried charge-generation region to the charge-readout region.