Patent ID: 8580601

Claim:
A method for fabricating a pixel sensor cell, the method comprising: forming a photosensing element beneath a top surface of a semiconductor layer; forming a gate dielectric for a first gate structure on the top surface of the semiconductor layer; forming a first section of a gate electrode for the first gate structure on the gate dielectric and adjacent to the photosensing element; and forming a second section of the gate electrode for the first gate structure on the gate dielectric and in a juxtaposed relationship with the first section of the gate electrode as a first layer of the gate electrode, wherein the first section of the gate electrode is formed with a lateral position in the first layer between the photosensing element and the second section of the gate electrode, the second section of the gate electrode is comprised of a conductor, and the first section of the gate electrode is comprised of a first metal having a higher work function than the conductor comprising the second section of the gate electrode so that the first gate structure has an asymmetric threshold voltage.