Image sensing device and methods of manufacturing the same
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsMing-Hsien Yang, Chun-Hao Chou, Kuo-Cheng Lee, Chung-Liang Cheng
Life of this patent
Estimating the term…
Abstract
Image sensing devices according to present disclosure include metal gate structures in a pixel device. Particularly, the metal gate structures include a ferroelectric layer and a conductive layer to form a negative capacitance device in the gate stack. As a result, the transistors in the pixel device have reduced threshold swing, improved gain and reduced threshold voltage shift. The pixel device according to the present disclosure includes a combination of metal gate and polycrystalline gate, which provides flexibility in pixel device design and improves performance.
Claims20
A method for forming an image sensing device, comprising:
- providing a substrate;
- forming an isolation structure in the substrate to define a pixel device region therein;
- forming two or more first gate structures over the pixel device region;
- doping the substrate to form source/drain regions on opposite sides of the two or more first gate structures;
- removing at least one of the two or more first gate structures;
- and
- forming a second gate structure in place of removed first gate structure, wherein the second gate structure and the first gate structures have different arrangement of material layers, and the second gate structure comprises a ferroelectric layer.
A method of forming a pixel device, comprising:
- forming a radiation region, a floating diffusion region, and two or more doped regions in a semiconductor substrate;
- forming a first gate structure on the semiconductor substrate, wherein the first gate structure overlaps with the radiation region and the floating diffusion region, wherein forming the first gate structure comprises:
- depositing a first gate dielectric layer on the semiconductor substrate;
- and
- depositing a first gate electrode layer on the first gate dielectric layer, wherein the first gate electrode layer comprises a polycrystalline silicon;
- and
- forming a second gate structure on the semiconductor substrate, wherein the second gate structure overlaps with the two or more doped regions, the first gate structure and the second gate structure include different arrangements of material layers, and at least one of the first gate structure and the second gate structure comprises a high-k gate dielectric layer having a k value greater than about 7.0, and the second gate structure is formed by a replacement gate process.
A method, comprising:
- forming an image sensing device comprising:
- a photodetector comprising a first pinned layer and a second pinned layer;
- a transfer transistor comprising a transfer gate overlapping with a portion of the photodetector, wherein the transfer gate includes a first group of material layers;
- a source-follower transistor comprising a source-follower gate;
- a reset transistor comprising a reset gate;
- and
- a select transistor comprising a select gate, wherein at least one of the source-follower gate, the reset gate, and the select gate includes a second group of material layers different from the first group of material layers, wherein at least one of the transfer gate, the source-follower gate, the reset gate and the select gate is fabricated by a replacement gate process.
Dependencies are inferred from the claim text.