Figure 4.

Three masks to create the p-well and the resultant potential profile (superposed). (a) The following three masks to create the linear p-well potential: mask 1 (yellow) covering the whole area except the center hole, mask 2 (light blue) with the comb-like structure, and mask 3 (blue) like a frame along the pixel boundary. The implantation energies are also different. (b) The potential profile over the p-well made with the masks (the linear potential is created, except the area near the center and the boundary of the pixel).