Solid-state imaging element and manufacturing method thereof

A manufacturing method of a solid-state imaging element, the method comprising:

• forming a plurality of photoelectric conversion units in a substrate;
• forming, on a first surface of the substrate, a third insulation film between a first photoelectric conversion unit of the plurality of photoelectric conversion units and a second photoelectric conversion unit of the plurality of photoelectric conversion units, wherein the first photoelectric conversion unit is adjacent to the second photoelectric conversion unit;
• forming, between the first photoelectric conversion unit and the second photoelectric conversion unit, a trench, wherein
• the trench penetrates between the first surface of the substrate and a second surface of the substrate, and
• the second surface of the substrate is opposite to the first surface of the substrate;
• forming, on an inner wall of the trench, a first insulation film having a fixed charge;
• forming a charge induction layer, wherein the charge induction layer is induced by the fixed charge of the first insulation film;
• forming, in the trench, a second insulation film on an inner side of the first insulation film;
• and
• forming at least one transistor on the first surface of the substrate, wherein
• the charge induction layer is a high-concentration charge layer of a first conductivity type,
• one of a source or a drain of the at least one transistor is a high-concentration impurity diffusion layer of a second conductivity type, and
• the first conductivity type is different from the second conductivity type.

A solid-state imaging element, comprising:

• a substrate;
• a plurality of photoelectric conversion units in the substrate;
• a second insulation film between a first photoelectric conversion unit of the plurality of photoelectric conversion units and a second photoelectric conversion unit of the plurality of photoelectric conversion units, wherein
• the first photoelectric conversion unit is adjacent to the second photoelectric conversion unit,
• the second insulation film is in a trench that penetrates between a first surface of the substrate and a second surface of the substrate, and
• the second surface of the substrate is opposite to the first surface of the substrate;
• a third insulation film on the first surface of the substrate, wherein
• the third insulation film is along both sides of the trench when viewed from the first surface of the substrate, and
• the third insulation film is wider than the second insulation film;
• and
• an impurity diffusion layer of a transistor on the first surface of the substrate, wherein
• the impurity diffusion layer of the transistor is in contact with a side surface of the third insulation film,
• a charge induction layer is induced by a fixed charge of the second insulation film,
• the charge induction layer is a high-concentration charge layer of a first conductivity type,
• the impurity diffusion layer of the transistor is of a second conductivity type,
• the first conductivity type is different from the second conductivity type, and
• the second insulation film is unexposed from the side surface of the third insulation film.

A manufacturing method of a solid-state imaging element, the method comprising:

• forming a plurality of photoelectric conversion units in a substrate;
• forming a trench between a first photoelectric conversion unit of the plurality of photoelectric conversion units and a second photoelectric conversion unit of the plurality of photoelectric conversion units, wherein
• the first photoelectric conversion unit is adjacent to the second photoelectric conversion unit,
• the trench extends from a first surface of the substrate to a second surface of the substrate, and
• the second surface of the substrate is opposite to the first surface of the substrate;
• forming a sacrificial film in the trench;
• forming a third insulation film on the first surface of the substrate, wherein the third insulation film is wider than the trench along both sides of the trench when viewed from the first surface of the substrate;
• removing the sacrificial film in the trench from a side of the second surface of the substrate;
• and
• forming a second insulation film in the trench from the side of the second surface of the substrate.