Image sensor

An image sensor, comprising:

• a substrate having a plurality of pixels, each pixel of the plurality of pixels including
• a photoelectric conversion region and a floating diffusion region in the substrate;
• a pixel transistor including a pixel gate on a first surface of the substrate,
• a first transmission gate between the photoelectric conversion region and the floating diffusion region, the first transmission gate extending into the substrate;
• and
• a second transmission gate between the photoelectric conversion region and the floating diffusion region, the second transmission gate between the pixel gate and the first transmission gate when viewed in a plan view, wherein
• an area of the second transmission gate is smaller than an area of the first transmission gate.

An image sensor, comprising:

• a substrate having a plurality of pixels that are each surrounded by a pixel device isolation layer, each pixel of the plurality of pixels including
• a photoelectric conversion region and a floating diffusion region in the substrate;
• a pixel transistor including a pixel gate on a first surface of the substrate;
• a first transmission gate adjacent to the photoelectric conversion region, the first transmission gate extending into the substrate, the first transmission gate having a first width in a horizontal direction extending parallel to the substrate;
• a second transmission gate adjacent to the photoelectric conversion region, the second transmission gate between the pixel gate and the first transmission gate when viewed in a plan view, the second transmission gate having a second width less than the first width in the horizontal direction;
• and
• a color filter on a second surface of the substrate, the second surface opposite to the first surface of the substrate,
• wherein
• the first transmission gate has a first height in a vertical direction extending perpendicular to the substrate, and
• the second transmission gate has a second height that is about 80% to about 120% of the first height in the vertical direction.