Publisher's Synopsis
Methods for forming image sensor structures are provided. The method includes forming an isolation structure in a substrate and forming a first light sensing region and a second light sensing region. The method further includes forming a first gate structure and a second gate structure, and the first gate structure and the second gate structure are positioned at a front side of the substrate. The method further includes forming a first source/drain structure adjacent to the first gate structure and a second source/drain structure adjacent to the second gate structure and forming an interlayer dielectric layer over the front side of the substrate. The method further includes forming a contact trench through the interlayer dielectric layer and forming a contact in the contact trench.