Industry Expert Talks: Enabling Next-Generation Image Sensors Through Back-End Integration of IGZO Electronics and Metasurfaces (video)
The continuous scaling of pixel size is increasingly constrained by the minimum area needed for pixel circuitry, while emerging applications demand simultaneously higher resolution, wider dynamic range, lower noise, and enhanced optical functionality. To address these challenges, imec is exploring a new image sensor architecture that combines back-end-of-line (BEOL) integrated Indium-Gallium-Zinc-Oxide (IGZO) thin-film transistors with advanced meta-optical components. BEOL-compatible IGZO devices can be deposited at temperatures below 400°C, enabling monolithic integration above CMOS circuitry without disrupting conventional image sensor manufacturing flows. This approach allows pixel transistors to be relocated from the silicon substrate into the metallization stack, further reducing area competition within the pixel and creating a pathway toward unprecedent pixel pitches while reducing the complexity and cost associated with 3D stacked wafers. Complementing these advances in electronics, flat optics offer a compelling pathway toward highly miniaturized optical systems with enhanced functionality. Nanostructured metasurfaces operating in the visible spectrum, combined with refractive optics, can significantly reduce the complexity of conventional multi-element refractive optical stacks while integrating additional optical functions, potentially at wafer level. This approach enables thinner camera modules, improved spectral and polarization selectivity, and novel computational imaging capabilities. At imec, we believe that the combination of BEOL-integrated IGZO electronics and wafer-level meta-optics establishes a compelling platform for next-generation visible, SWIR, multispectral, and polarization-sensitive image sensors. Together, these innovations enable higher performance, greater functional integration, and a new level of miniaturization to support future portable, wearable, robotic, and other consumer imaging applications where device size and sensing performance are critical differentiators.
