Global shutter pixel with improved efficiency

摘要

A global shutter pixel cell includes a serially connected anti-blooming (AB) transistor, storage gate (SG) transistor and transfer (TX) transistor. The serially connected transistors are coupled between a voltage supply and a floating diffusion (FD) region. A terminal of a photodiode (PD) is connected between respective terminals of the AB and the SG transistors; and a terminal of a storage node (SN) diode is connected between respective terminals of the SG and the TX transistors. A portion of the PD region is extended under the SN region, so that the PD region shields the SN region from stray photons. Furthermore, a metallic layer, disposed above the SN region, is extended downwardly toward the SN region, so that the metallic layer shields the SN region from stray photons. Moreover, a top surface of the metallic layer is coated with an anti-reflective layer.

主权项

1. A pixel cell comprising:
a photodiode (PD) region in a semiconductor for generating charge, and a storage node (SN) region in the semiconductor, selectively connected to the PD region, for holding a charge transferred from the PD region, wherein a top portion of the PD region is implanted adjacent to a side of the SN region, a bottom portion of the PD region is extended under the SN region, the bottom portion of the PD region is effective in reducing parasitic charges diffusing to the SN region, a P-well region is implanted under the SN region, and a high dose p-type isolation region is implanted in the P-well region, and is disposed under the SN region for reducing parasitic charges diffusing to the SN region, wherein the top portion of the PD region is smaller in width than the bottom portion of the PD region, and a side of the top portion of the PD region is connected to the bottom portion of the PD region by an angular section extending under the SN region.