Imec has unveiled a fundamentally new method for faithful color splitting in CMOS imagers, achieving sub-micron resolution with significantly enhanced performance. Presented at IEEE IEDM 2023, this technology utilizes an array of vertical Si3N4 multimode waveguides that spatially separate colors based on a "beating pattern" of light modes. It overcomes the limitations of traditional color filters (which absorb up to 70% of light) and existing diffraction-based splitters by collecting over 90% of incident photons, delivering a higher signal-to-noise ratio, superior color quality (Vora value > 95%), and unprecedented spatial resolution beyond the Abbe diffraction limit. Compatible with standard 300mm back-end processing, this cost-efficient approach is poised to revolutionize high-end camera performance for applications such as smartphones, automotive, and medical imaging.
Imec's Revolutionary Color Rendering Technology for Next-Gen Cameras
Novel Color Splitting Method: Imec has developed a "fundamentally new way" to faithfully split colors at sub-micron pixel sizes, surpassing the Abbe diffraction limit, using standard back-end-of-line processing on 300mm wafers.
Addressing Current Limitations: This technology resolves issues with traditional color filters (which absorb up to 70% of incoming light and suffer from interpolation artifacts at high pixel densities) and existing diffraction-based color splitters (which improve sensitivity but not image resolution).
Waveguide-Based System: The core innovation involves an array of vertical Si3N4 multimode waveguides embedded in an SiO2 matrix, with tapered, diffraction-limited sized inputs (e.g., 800x800 nmΒ²) to collect light efficiently.
Mechanism of Color Separation: Within each waveguide, incident photons excite both symmetric and asymmetric modes. The different propagation of these modes creates a unique "beating pattern" for each light frequency, leading to spatial separation of colors at the waveguide's output.
Superior Light Collection and Color Accuracy: The system achieves over 90% light output within the human color perception range (400-700nm), offering a significant advantage over color filters. It also delivers exceptional color accuracy (Vora value > 95%).
Key Performance Enhancements: The technology promises higher signal-to-noise ratio, enhanced color quality, and unprecedented spatial resolution. It aims to detect every incident photon and its properties, enabling further scaling of high-resolution imagers.
Cost-Effective and Scalable: Compatibility with standard 300mm processing ensures that these splitters can be produced cost-efficiently, making them viable for widespread adoption.
Broad Applications and Future Vision: Imec's ambition is for this technology to become the future standard for color imaging with diffraction-limited resolution, with target markets including smartphones, automotive, and medical (endoscopy). Imec is actively seeking industry partners for full camera demonstrations.