Microstructured Passivation Layer for Higher Image Sensor Light Absorption

The patent applies curvature by forming microstructures (such as hemispheres, domes, or rounded shapes) on the passivation layer surface. These curved surfaces cause incident light to undergo multiple reflections and refractions, increasing the optical path length and absorption ratio. The curved geometry transforms the flat surface into a light-trapping structure that reduces reflection loss while maintaining manufacturing feasibility through standard semiconductor processing techniques.

The patent segments the passivation layer surface into multiple microstructures (arrays of small hemispheres, domes, or rounded elements) rather than using a single flat surface. Each microstructure independently traps light through multiple reflections, and the collective array provides comprehensive light absorption across the sensor surface. This segmentation approach maintains ease of manufacture through standard photolithography and etching processes while dramatically improving light absorption ratio.

The patent employs self-service by forming microstructures that automatically trap and absorb light through their inherent geometric properties, without requiring additional active components or complex control mechanisms. The microstructures (hemispheres, domes, or rounded shapes) passively redirect incident light through multiple reflections and refractions, causing the structure itself to serve the light absorption function. This eliminates the need for external light-trapping mechanisms while maintaining manufacturing simplicity through standard semiconductor processing.