Imaging apparatus and electronic apparatus having a transfer transistor gate electrode extending into a pixel separation section from a first surface to a second surface of a semiconductor substrate
An imaging apparatus includes a plurality of pixels each including a photoelectric conversion section that is located in a pixel region divided by the pixel separation section and generates a charge according to incident light, a floating diffusion that holds the charge generated by the photoelectric conversion section, and a transfer transistor that transfers the charge from the photoelectric conversion section to the floating diffusion. The transfer transistor has a gate electrode that extends into the pixel separation section, along a thickness direction of a first semiconductor substrate, from a second surface of the first semiconductor substrate located on an opposite side to a first surface that is a light incident surface of the first semiconductor substrate.
1 . An imaging apparatus, comprising:
a first semiconductor substrate;
a plurality of pixels arranged along a row direction and a column direction on the first semiconductor substrate, the plurality of pixels being adjacent to each other, and
a pixel separation section that partitions the first semiconductor substrate into a plurality of pixel regions in which the pixels are respectively arranged, wherein
each of the plurality of pixels includes
a photoelectric conversion section that is located in one of the pixel regions partitioned by the pixel separation section and generates a charge according to incident light,
a floating diffusion that holds the charge generated by the photoelectric conversion section, and
a transfer transistor that transfers the charge from the photoelectric conversion section to the floating diffusion, and
the transfer transistor has a gate electrode that extends into the pixel separation section, along a thickness direction of the first semiconductor substrate, from a second surface of the first semiconductor substrate located on an opposite side to a first surface that is a light incident surface of the first semiconductor substrate.
2 . The imaging apparatus according to claim 1 , wherein
the gate electrode of the transfer transistor extends into the pixel separation section adjacent to the floating diffusion.
3 . The imaging apparatus according to claim 2 , wherein
the gate electrode extends from the second surface to a midway of the first semiconductor substrate along the thickness direction of the first semiconductor substrate.
4 . The imaging apparatus according to claim 1 , wherein
the floating diffusion contains an impurity of a first conductivity type, and
each of the pixels includes
a diffusion region provided at a position having a point symmetrical relationship with the floating diffusion with respect to a center point of the pixel when viewed from above the second surface, and containing an impurity of a second conductivity type different from the first conductivity type.
5 . The imaging apparatus according to claim 1 , further comprising
a second semiconductor substrate facing the second surface, wherein
the second semiconductor substrate includes
a reset transistor that resets a potential of the floating diffusion to a predetermined potential,
an amplification transistor that generates a voltage signal corresponding to the charge held in the floating diffusion, and
a selection transistor that controls an output timing of the voltage signal from the amplification transistor.
6 . The imaging apparatus according to claim 5 , wherein
the second semiconductor substrate includes the reset transistor, the amplification transistor, and the selection transistor for each of the pixels.
7 . The imaging apparatus according to claim 5 , wherein
the floating diffusion is shared by two or more of the pixels, and
the second semiconductor substrate includes the reset transistor, the amplification transistor, and the selection transistor for every the two or more of the pixels sharing the floating diffusion.
8 . The imaging apparatus according to claim 7 , wherein
the floating diffusion is shared by four of the pixels.
9 . The imaging apparatus according to claim 5 , wherein
the first semiconductor substrate and the second semiconductor substrate are electrically connected via a connecting section.
10 . The imaging apparatus according to claim 9 , wherein
the floating diffusion and the amplification transistor are electrically connected via the connecting section.
11 . The imaging apparatus according to claim 1 , wherein
the gate electrode of the transfer transistor has a substantially L-shape when viewed from above the second surface.
12 . The imaging apparatus according to claim 1 , wherein
the gate electrode of the transfer transistor is located between the pixels adjacent in the column direction.
13 . The imaging apparatus according to claim 1 , wherein
the gate electrode of the transfer transistor is located between the pixels adjacent in the row direction.
14 . The imaging apparatus according to claim 1 , wherein
the transfer transistor of each of the pixels has a plurality of the gate electrodes,
one of the plurality of gate electrodes is located between the pixels adjacent in the column direction, and
another one of the plurality of gate electrodes is located between the pixels adjacent in the row direction.
15 . The imaging apparatus according to claim 8 , wherein
the four of the pixels sharing the floating diffusion are arranged in two rows and two columns, and
the gate electrode of the transfer transistor of each of the four of the pixels sharing the floating diffusion is located between the pixels adjacent among the four of the pixels.
16 . The imaging apparatus according to claim 15 , wherein
a width of the pixel separation section in a portion where corners of the four of the pixels arranged in the two rows and the two columns face each other is wider than a width of the pixel separation section surrounding the four of the pixels.
17 . The imaging apparatus according to claim 1 , wherein the pixel separation section includes an insulating layer in the pixel separation section.
18 . The imaging apparatus according to claim 17 , wherein
the pixel separation section further includes a conductive material in the pixel separation section, and
the conductive material extends from a side of the first surface in the thickness direction of the first semiconductor substrate.
19 . The imaging apparatus according to claim 18 , wherein the conductive material includes polysilicon.
20 . An electronic apparatus comprising an imaging apparatus including a first semiconductor substrate, a plurality of pixels arranged along a row direction and a column direction on the first semiconductor substrate, the plurality of pixels being adjacent to each other, and a pixel separation section that partitions the first semiconductor substrate into a plurality of pixel regions in which the pixels are respectively arranged, wherein
each of the plurality of pixels includes
a photoelectric conversion section that is located in one of the pixel regions partitioned by the pixel separation section and generates a charge according to incident light,
a floating diffusion that holds the charge generated by the photoelectric conversion section, and
a transfer transistor that transfers the charge from the photoelectric conversion section to the floating diffusion, and
the transfer transistor has a gate electrode that extends in the pixel separation section, along a thickness direction of the first semiconductor substrate, from a second surface of the first semiconductor substrate located on an opposite side to a first surface that is a light incident surface of the first semiconductor substrate.