An uneven-trench pixel cell includes a semiconductor substrate that includes a floating diffusion region, a photodiode region, and, between a front surface and a back surface: a first sidewall surface, a shallow bottom surface, a second sidewall surface, and a deep bottom surface. The first sidewall surface and a shallow bottom surface define a shallow trench, located between the floating diffusion region and the photodiode region, that extends into the semiconductor substrate from the front surface. A shallow depth of the shallow trench exceeds a junction depth of the floating diffusion region. The second sidewall surface and a deep bottom surface define a deep trench, located between the floating diffusion region and the photodiode region, that extends into the semiconductor substrate from the front surface. A distance between the deep bottom surface and the front surface defines a deep depth, of the deep trench, that exceeds the shallow depth.