Pixel of an image sensor, and image sensor

摘要

A pixel of an image sensor includes a photoelectric conversion region formed in a semiconductor substrate, a floating diffusion region formed in the semiconductor substrate, the floating diffusion region being spaced apart from the photoelectric conversion region, a vertical transfer gate extending from a first surface of the semiconductor substrate into a recess in the semiconductor substrate, and configured to form a transfer channel between the photoelectric conversion region and the floating diffusion region, and an impurity region surrounding the recess. The impurity region has a first impurity concentration at a region adjacent to a side of the recess, and a second impurity concentration higher than the first impurity concentration at a region adjacent to the bottom of the recess.

主权项

1. A pixel comprising:
a photoelectric conversion region in a semiconductor substrate having first and second opposite major surfaces, the photoelectric conversion region being spaced from the first surface such that the top of the photoelectric conversion region faces towards the first surface; a floating diffusion region in the semiconductor substrate, the floating diffusion region being vertically spaced relative to the photoelectric conversion region in the pixel; a vertical transfer gate extending from the first surface of the semiconductor substrate into a recess in the semiconductor substrate, the vertical transfer gate being disposed atop the photoelectric conversion region, and the vertical transfer gate being operable to form a transfer channel between the photoelectric conversion region and the floating diffusion region; and an impurity region surrounding the recess, the impurity region having a first region extending facing a side of the recess above the photoelectric conversion region and interposed between the transfer gate and the floating diffusion region, and a second region facing a bottom of the recess as interposed between the upper surface of the photoelectric conversion region and a surface of the vertical transfer gate that faces towards the second surface of the substrate, and the impurity region also having a bend therein, the bend forming a corner at which the first and second regions join one another, and wherein the transfer channel, along which charges transfer to the floating diffusion region from the photoelectric conversion region, includes the bend and the first region of the impurity region, and the first region of the impurity region has a first impurity concentration, and the second region of the impurity region has a second impurity concentration higher than the first impurity concentration.