Pixel sensor cell with a dual work function gate electode

A pixel sensor cell comprising:

• a photosensing element;
• a floating diffusion region;
• and
• a gate structure configured to control carrier transfer from the photosensing element to the floating diffusion region, the gate structure including a gate electrode and a gate dielectric, the gate electrode including a first layer comprised of a first section and a second section in a juxtaposed relationship on the gate dielectric with the first section, the second section of the gate electrode comprised of a conductor, and the first section of the gate electrode comprised of a first metal having a higher work function than the conductor comprising the second section of the gate electrode so that the gate structure has an asymmetric threshold voltage,
• wherein the first metal is a transition metal, the conductor comprises a transition metal, the gate electrode includes a second layer comprised of polysilicon, and the first layer of the gate electrode is positioned between the second layer of the gate electrode and the gate dielectric.

A pixel sensor cell comprising:

• a photosensing element;
• a floating diffusion region;
• and
• a gate structure configured to control carrier transfer from the photosensing element to the floating diffusion region, the gate structure including a gate electrode and a gate dielectric, the gate electrode including a first layer comprised of a first section and a second section in a juxtaposed relationship on the gate dielectric with the first section, the second section of the gate electrode comprised of a conductor, and the first section of the gate electrode comprised of a first metal having a higher work function than the conductor comprising the second section of the gate electrode so that the gate structure has an asymmetric threshold voltage,
• wherein the conductor comprises polysilicon, the gate electrode includes a second layer comprised of polysilicon, and the first layer of the gate electrode is positioned between the second layer of the gate electrode and the gate dielectric.

A hardware description language (HDL) design structure encoded on a machine-readable data storage medium, the HDL design structure comprising elements that when processed in a computer-aided design system generates a machine-executable representation of a pixel sensor cell, the HDL design structure comprising:

• a photosensing element;
• a floating diffusion region;
• and
• a gate structure configured to control carrier transfer from the photosensing element to the floating diffusion region, the gate structure including a gate electrode and a gate dielectric, the gate electrode including a first layer comprised of a first section and a second section in a juxtaposed relationship on the gate dielectric with the first section, the second section of the gate electrode comprised of a conductor, and the first section of the gate electrode comprised of a first metal having a higher work function than the conductor comprising the second section of the gate electrode so that the gate structure has an asymmetric threshold voltage,
• wherein the first section of the gate electrode is laterally positioned in the first layer between the photosensing element and the second section of the gate electrode.