Parasitic coupling in 3D equential integration: the example of a two-layer 3D pixel

authors

• Sideris Petros
• Peizerat Arnaud
• Batude Perrine
• Sicard Gilles
• Theodorou Christoforos

keywords

• Image sensors 3D pixels 3D sequential integration 3DSI monolithic 3D M3D coupling parasitic capacitances
• Image sensors
• 3D pixels
• 3D sequential integration
• 3DSI
• Monolithic 3D
• M3D
• Coupling
• Parasitic capacitances

abstract

In this paper, we present a thorough analysis of parasitic coupling effects between different electrodes for a 3D Sequential Integration circuit example comprising stacked devices. More specifically, this study is performed for a BackSide Illuminated, 4T-APS, 3D Sequential Integration pixel with both its photodiode and Transfer Gate at the bottom tier and the other parts of the circuit on the top tier. The effects of voltage bias and 3D inter-tier contacts are studied by using TCAD simulations. Coupling-induced electrical parameter variations are compared against variations due to temperature change, revealing that these two effects can cause similar levels of readout error for the top-tier readout circuit. On the bright side, we also demonstrate that in the case of a rolling shutter pixel readout, the coupling effect becomes nearly negligible. Therefore, we estimate that the presence of an inter-tier ground plane, normally used for electrical isolation, is not strictly mandatory for Monolithic 3D pixels.

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