Optical Waveguide Layer for CMOS Image Sensor Cross-Talk Reduction

The patent divides the optical waveguide layer into multiple segments corresponding to each pixel, with each segment having its own optical waveguide structure. This segmentation isolates the light paths of adjacent pixels, preventing cross-talk while maintaining high resolution. The partition grid structure further divides the space between pixels, creating distinct optical channels for each pixel element.

The patent applies different refractive index materials locally to specific pixel regions. The optical waveguide layer uses high refractive index material in pixel-specific regions and low refractive index material in partition regions. This local differentiation of optical properties directs light locally into the correct pixel while blocking oblique light from neighboring pixels, solving the cross-talk problem without compromising resolution.

The patent employs a universal optical waveguide layer structure that serves multiple functions simultaneously: it guides light for all pixels, provides optical isolation between pixels, and maintains consistent optical properties across the entire pixel array. The partition grid structure also serves dual purposes as both a mechanical support framework and an optical isolation barrier, simplifying manufacturing by combining multiple functions into unified structures.

The patent controls the refractive index parameter of the optical waveguide layer materials to achieve the desired optical performance. By selecting materials with specific refractive index values (high index for waveguide regions, low index for partition regions), the patent optimizes light guidance and isolation properties without changing the physical dimensions of the pixel structure, thereby avoiding the manufacturing difficulties associated with sub-micron dimensional precision.

The patent introduces an intermediary optical waveguide layer between the incident light and the pixel array. This intermediate structure receives oblique incident light and redirects it through total internal reflection to enter pixels at appropriate angles. The waveguide layer acts as a mediator that transforms the direction of oblique light without requiring complex light collection optics, maintaining manufacturing simplicity while ensuring reliable image detection by preventing cross-talk at pixel edges.

The patent replaces mechanical light collection systems (such as complex lens arrays or microlens structures) with an optical waveguide-based light guidance system. Instead of using mechanical means to focus and direct light, the patent employs optical principles (total internal reflection, refraction) to guide light through the waveguide layer into the pixels. This substitution simplifies the light collection mechanism while improving reliability by eliminating the cross-talk problems associated with direct oblique light incidence.