Image sensor including a pixel separation structure

An image sensor, comprising:

• a semiconductor substrate that has a first surface and a second surface opposite to each other;
• a first pixel separation structure that vertically extends from the first surface of the semiconductor substrate and provides a pixel region, wherein the first pixel separation structure includes:
• a plurality of first parts that extend in a first direction,
• a plurality of second parts that extend in a second direction intersecting the first direction, and
• a plurality of first intersection parts that are connected to the plurality of first and the plurality of second parts;
• and
• a second pixel separation structure that overlaps the first pixel separation structure and vertically extends from the second surface of the semiconductor substrate, wherein the second pixel separation structure includes:
• a plurality of third parts that extend in the first direction,
• a plurality of fourth parts that extend in the second direction, and
• a plurality of second intersection parts that are connected to the plurality of third and the plurality of fourth parts,
• wherein the plurality of first and the plurality of second parts have a first vertical length, and the first intersection parts have a second vertical length different from the first vertical length, and
• wherein the plurality of third and the plurality of fourth parts have a third vertical length, and that the plurality of second intersection parts have a fourth vertical length different from the third vertical length.

An image sensor, comprising:

• a semiconductor substrate that has a first surface and a second surface opposite to each other, wherein the semiconductor substrate includes a light-receiving region, a light-shielding region, and a pad region;
• a first pixel separation structure that vertically extends from the first surface of the semiconductor substrate on the light-receiving, light-shielding, and pad regions;
• a second pixel separation structure that vertically extends from the second surface of the semiconductor substrate on the light-receiving, light-shielding, and pad regions, wherein the second pixel separation structure overlaps the first pixel separation structure;
• a plurality of photoelectric conversion regions in the semiconductor substrate on the light-receiving and light-shielding regions;
• a plurality of scattering patterns in the second surface of the semiconductor substrate on the light-receiving and light-shielding regions, wherein the scattering patterns overlap the plurality of photoelectric conversion regions;
• a contact plug disposed on a portion of the light-shielding region, wherein the contact plug is adjacent to the second surface of the semiconductor substrate and is in contact with a portion of the first pixel separation structure;
• a conductive pad disposed on the second surface of the semiconductor substrate and on the pad region;
• a grid structure disposed on the second surface of the semiconductor substrate;
• and
• a microlens array disposed on the grid structure.