| CPC H01L 27/14643 (2013.01) [H01L 27/14683 (2013.01); H01L 27/14831 (2013.01); H01L 27/14887 (2013.01); H01L 29/4236 (2013.01)] | 25 Claims |
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1. An uneven-trench pixel cell comprising:
a semiconductor substrate that includes a floating diffusion region and a photodiode region; and, between a front surface and a back surface opposing the front surface of the semiconductor substrate:
(i) a first sidewall surface and a shallow bottom surface defining a shallow trench located between the floating diffusion region and the photodiode region and extending into the semiconductor substrate from the front surface, a distance between the shallow bottom surface and the front surface defining a shallow depth of the shallow trench that exceeds a junction depth of the floating diffusion region relative to the front surface; and
(ii) a second sidewall surface and a deep bottom surface defining a deep trench located between the floating diffusion region and the photodiode region and extending into the semiconductor substrate from the front surface, a distance between the deep bottom surface and the front surface defining a deep depth, of the deep trench, that exceeds the shallow depth;
the distance defining the shallow depth being in a depth direction, the shallow trench and the deep trench being located between the floating diffusion region and the photodiode region in a first direction, the shallow trench being laterally displaced from the deep trench in a second direction that is perpendicular to the first direction, each of the first direction and the second direction being perpendicular to the depth direction.
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