Nmos SOI Source Follower Floating Body Effects Mitigation and Pixel Level Induced Noise Modeling in 3D Sequentially Integrated BSI CIS
Student Contest:
Yes
Affiliation Type:
Industry
Keywords:
FBE, noise, 3DSI, CIS, SOI, ground-plane
Abstract:
This paper reports floating body effect (FBE)-induced noise degradation in 3D sequential integration (3DSI) CMOS image sensors (CIS) using SOI source follower (SF) MOSFETs. Statistical measurements on 3DSI pixels show a strong increase in temporal noise when impact ionization-driven FBE is activated, degrading sensor performance. The FBE onset at the pixel operating point is reproduced by TCAD and device-level measurements. Based on these insights, an experimentally validated physics-based transient model is developed to link correlated double sampling (CDS)-dependent noise to floating body charge dynamics. A circuit-friendly calibration and mitigation flow is proposed, including an operating window map for bias and timing optimization, which provides guidelines for robust low-noise CIS design. In our case, a 69% noise reduction is achieved without circuit modification. Additionally, a ground-plane (GP) variant with dynamic back-bias control is demonstrated, enabling FBE mitigation. To the best of our knowledge, this work advances the state of the art as the first to characterize FBE in SOI-based CIS technologies.
Track ID:
14
Track Name:
Devices & Circuits for Sensors, Imagers and Displays
