Taiwan Semiconductor Manufacturing Comp. Ltd.

An Ming Chiang

Wei-Kun Yeh

Hua-Yu Yang

Chi-Hsiang Lee

An active pixel sensor cell, and the process for forming the active pixel sensor cell, featuring a pinned photodiode structure, and a readout region, located in a region of the pinned photodiode structure, has been developed. The process features the formation of a N&plus; readout region, performed simultaneously with the formation of the N&plus; source/drain region of the reset transistor, however with the N&plus; readout region placed in an area to be used for the pinned photodiode structure. The pinned photodiode structure is next formed via formation of a lightly doped N type well region, used as the lower segment of the pinned photodiode structure, followed by the formation of P&plus; region, used as the top segment of the pinned photodiode structure, with the N&plus; readout region, surrounded by the P&plus; region. The placement of the N&plus; readout region, in a region of the pinned photodiode structure, eliminates the need for a transfer transistor, for the active pixel sensor cell, and results in a higher signal to noise ratio, as well as lower dark current generation, than counterparts fabricated without the use of the process, and structure, of this invention.

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Hsin-Chu, Taiwan

An Ming Chiang