A method of fabricating CMOS image sensors is disclosed. In contrast to traditional fabrication processes, the present sequence implants dopants into the epitaxial layer from both the first surface and the second surface. Because dopant is introduced through both sides, the maximum implant energy to perform the implant may be reduced by as much as 50%. In certain embodiments, the second implant is performed prior to the application of the electrical contacts. In another embodiments, the second implant is performed after the application of the electrical contacts. This method may allow deeper photodiodes to be fabricated using currently available semiconductor processing equipment than would otherwise be possible.