Boundary Trench Isolation Effects on a Stacked Gradient Homojunction Photodiode Architecture

In this paper, the effect of the width of inter-pixel boundary trench isolation (BTI) on the response resolution of a two dimensional CMOS compatible photodiode array that has a stacked gradient homojunction (StaG) architecture, was simulated. Results were compared with the StaG photodiode with and without inter-pixel nested ridges. Backwall illumination showed increasing crosstalk as the BTI width increased due to more crosstalk carriers channeling into the widening trench. Frontwall illumination showed a reduction in crosstalk up to a BTI width of 5 mum, which was more reduced than for the backwall illumination. Both modes of illumination showed superior sensitivity compared to the StaG photodiode with and without ridges. However the StaG photodiode with ridges is still superior in reducing crosstalk than the StaG photodiode with BTI due to it being a more efficient minority carrier mirror.