| 摘要 |
Provided is a light sensing pixel including an image sensor. In a general four-transistor Complementary Metal-Oxide Semiconductor (CMOS) image sensor, unlike a conventional structure, a transfer transistor in a pixel includes a depletion region separated from a channel that is not influenced by a turn-on voltage of the transfer transistor regardless of a driving voltage or a driving method when a photodiode is reset and transferred. As a result, dark current or fixed pattern noise, caused by a change in operating condition of the transfer transistor and inconsistent characteristics between the pixels, is reduced. The image sensor includes a light sensing pixel that includes the transfer transistor for transferring a light-induced charge generated by the photodiode. The light sensing pixel, to dispose the depletion region between the channel of the transfer transistor and a diffusion node, i.e., to operate in the similar pinch-off state, may have a structure in which an insulating layer of the diffusion node side is thicker than a gate insulating layer adjacent to the photodiode in the transfer transistor. That is, the insulating layer of the transfer transistor has steps or a gradual change in thickness. Also, the light sensing pixel may have a structure in which pocket/halo implant using electrically the same material as a doping material of a substrate is performed between the channel of the transfer transistor and the diffusion node.
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