Vertical Transfer Gate Shape Impact on Full Well and Transfer Capabilities in a Photogate Pixel

Pixel shrinking requires new implementation of key components, such as the Vertical Transfer Gate (VEGA) for PhotoGate (PG) pixel architecture. High performances in terms of Full Well and charge transfer capacities are mandatory. We have investigated different strategies of VEGA implementation, with design and testing of three pixel variants: square VEGA (reference), I-shaped VEGA and L-shaped one. Both I-and L-shaped configurations are suitable for further pixel shrinking. Short I-shaped configuration gives a slightly improved Full Well Capacity (FWC) versus reference, while L-shaped variant brings a more significant FWC improvement of about $\mathbf{1 0 \%}$ compared to reference. Both configurations achieve a PRNU similar to the reference.