Solid-state imaging apparatus, method of manufacturing solid-state imaging apparatus, and electronic apparatus
View Patent ↗A solid-state imaging apparatus includes a transfer gate electrode formed on a semiconductor substrate; a photoelectric conversion unit including an electric charge storage area that is formed from a surface side of the semiconductor substrate in a depth direction, a transfer auxiliary area formed of a second conductive type impurity area that is formed in such a manner as to partially overlap the transfer gate electrode, and a dark current suppression area that is a first dark current suppression area formed in an upper layer of the transfer auxiliary and formed so as to have positional alignment in such a manner that the end portion of the transfer auxiliary area on the transfer gate electrode side is at the same position as the end portion of the transfer auxiliary area; and a signal processing circuit configured to process an output signal output from the solid-state imaging apparatus.
1. A back-illuminated solid-state imaging apparatus comprising:
a transfer gate electrode formed on a semiconductor substrate; and
a photoelectric conversion unit including
an electric charge storage area that is formed from a surface side of the semiconductor substrate in a depth direction, the electric charge storage area being formed of a first conductive type impurity area that is formed so as to partially overlap the transfer gate electrode,
a transfer auxiliary area formed of a second conductive type impurity area that is formed in such a manner as to partially overlap the transfer gate electrode, the transfer auxiliary area being formed in an upper layer of the electric charge storage area, and
a dark current suppression area that is a first dark current suppression area formed in an upper layer of the transfer auxiliary area and formed so as to have positional alignment in such a manner that an end portion of the first dark current suppression area on a side overlapping the transfer gate electrode is at the same position as an end portion of the transfer auxiliary area partially overlapping the transfer gate electrode, the dark current suppression area being formed of an impurity area having a same conductive type as the transfer auxiliary area and wherein the impurity area has the same conductive type in a higher concentration than that of the transfer auxiliary area.
2. The back-illuminated solid-state imaging apparatus according to claim 1 , wherein the photoelectric conversion unit includes an outermost surface dark current suppression area that is formed on an outermost surface of the semiconductor substrate in an upper layer of the transfer auxiliary area and that does not extend below the transfer gate electrode, the outermost surface dark current suppression area being formed of an impurity area of a conductive type the same as that of the dark current suppression area and being formed of an impurity area having the same conductive type in a higher concentration than that of the dark current suppression area.
3. The back-illuminated solid-state imaging apparatus according to claim 2 , further comprising a reading area from which signal electric charge that is transferred from the photoelectric conversion unit is read on the surface side of the semiconductor substrate,
wherein an amount of the partial overlap between the transfer auxiliary area and the transfer gate electrode is made to be larger on the reading area side than an amount of the partial overlap between the electric charge storage area and the transfer gate electrode.
4. The solid-state imaging apparatus according to claim 3 ,
wherein the transfer gate electrode includes a side wall on the side surface of the transfer gate electrode, and
wherein the outermost surface dark current suppression area is formed so as to overlap below the side wall.
5. The solid-state imaging apparatus according to claim 1 , wherein the end portion on the transfer gate electrode side of the electric charge storage area is set at substantially the same position as the end portion on the transfer gate electrode side of the dark current suppression area and the transfer auxiliary area.
6. An electronic apparatus comprising:
an optical lens;
a back-illuminated solid-state imaging apparatus to which light collected in the optical lens enters, the back-illuminated solid-state imaging apparatus including
a photoelectric conversion unit including
a transfer gate electrode formed on a semiconductor substrate, and
an electric charge storage area that is formed from a surface side of the semiconductor substrate in a depth direction, the electric charge storage area being formed of a first conductive type impurity area that is formed so as to partially overlap the transfer gate electrode,
a transfer auxiliary area formed of a second conductive type impurity area that is formed so as to partially overlap the transfer gate electrode, the transfer auxiliary area being formed in an upper layer of the electric charge storage area, and
a dark current suppression area that is formed in an upper layer of the transfer auxiliary area in such a manner that an end portion of the dark current suppression area on a side overlapping the transfer gate electrode has positional alignment with an end portion of the transfer auxiliary area on a side overlapping the transfer gate electrode, the dark current suppression area being formed of an impurity area of a conductive type the same as that of the transfer auxiliary area and wherein the impurity area has the same conductive type in a higher concentration than that of the transfer auxiliary area; and
a signal processing circuit configured to process a signal output from the back-illuminated solid-state imaging apparatus.
7. The electronic apparatus according to claim 6 , wherein the photoelectric conversion unit includes an outermost surface dark current suppression area that is formed on an outermost surface of the semiconductor substrate in an upper layer of the transfer auxiliary area and that does not extend below the transfer gate electrode, the outermost surface dark current suppression area being formed of an impurity area of a conductive type the same as that of the dark current suppression area and being formed of an impurity area having the same conductive type in a higher concentration than that of the dark current suppression area.
8. The electronic apparatus according to claim 7 , further comprising a reading area from which signal electric charge that is transferred from the photoelectric conversion unit is read on the surface side of the semiconductor substrate,
wherein an amount of the partial overlap between the transfer auxiliary area and the transfer gate electrode is made to be larger on the reading area side than an amount of the partial overlap between the electric charge storage area and the transfer gate electrode.
9. The electronic apparatus according to claim 8 ,
wherein the transfer gate electrode includes a side wall on the side surface of the transfer gate electrode, and
wherein the outermost surface dark current suppression area is formed so as to overlap below the side wall.
10. The electronic apparatus according to claim 6 , wherein the end portion on the transfer gate electrode side of the electric charge storage area is set at substantially the same position as the end portion on the transfer gate electrode side of the dark current suppression area and the transfer auxiliary area.