Imaging sensor having floating region of imaging device on one substrate electrically coupled to another floating region formed on a second substrate

An image sensor may include a symmetrical imaging pixel with a floating diffusion region. The floating diffusion region may be formed in the center of the imaging pixel. A shallow p-well may be formed around the floating diffusion region. A transfer gate configured to transfer charge from a photodiode to the floating diffusion region may be ring-shaped with an opening that overlaps the floating diffusion region. Isolation regions including deep trench isolation and a p-well may surround the photodiode of the imaging pixel. A p-stripe may couple the shallow p-well around the floating diffusion region to the isolation regions. The floating diffusion regions of neighboring pixels may be coupled together with additional conductive layers to implement shared configurations.