Imaging element and imaging device having a polygonal transfer gate opening

An imaging device, comprising:

• a photoelectric conversion unit disposed in a semiconductor substrate, wherein a first surface of the photoelectric conversion unit is adjacent a first surface of the semiconductor substrate, and wherein a second surface of the photoelectric conversion unit is adjacent a second surface of the semiconductor substrate;
• a charge holding unit disposed in the semiconductor substrate;
• a charge transfer unit,
• wherein an opening portion of the charge transfer unit is formed in the first surface of the semiconductor substrate,
• wherein the opening portion of the charge transfer unit has a first polygonal shape in a plan view,
• wherein an embedded gate is disposed in the opening portion and extends from a first point adjacent to the first surface of the semiconductor substrate to a second point between the first surface of the semiconductor substrate and the second surface of the semiconductor substrate,
• wherein the second point is between the first surface of the photoelectric conversion unit and the second surface of the photoelectric conversion unit,
• wherein the embedded gate extends through an area that intersects an area of the photoelectric conversion unit in the plan view,
• wherein a portion of the photoelectric conversion unit is disposed between a portion of the embedded gate and the second surface of the semiconductor substrate, and
• wherein the embedded gate has the first polygonal shape;
• an image signal generation unit configured to generate an image signal based on charge transferred from the charge holding unit to the image signal generation unit;
• and
• a processing circuit configured to process the generated image signal, wherein the opening portion having the first polygonal shape is formed by performing recrystallization of a member constituting the semiconductor substrate, so that crystal orientation planes are formed at sides of the first polygonal shape.