Photodetector Isolation Structure for Higher Photon Capture

The patent introduces a vertical dimension by forming a protruding portion that extends upward from the deep trench isolation structure. This three-dimensional structure creates an inclined reflective surface that redirects photons in the vertical and angular dimensions, allowing photons that would otherwise be lost to the isolation structure to be reflected back into the photosensitive area, thus recovering effective photosensitive area while maintaining optical isolation.

The patent converts the harmful effect of the deep trench isolation structure (which blocks and absorbs photons, reducing effective photosensitive area) into a beneficial effect by adding a protruding portion with an inclined surface that reflects photons back into the photosensitive area. The isolation structure that was previously a source of photon loss becomes a photon redirecting element that improves photon utilization.

The protruding portion adds a vertical dimension to the isolation structure, creating an inclined reflective surface that redirects photons in three-dimensional space. This allows photons incident on the isolation structure to be reflected back into the photosensitive area at appropriate angles, increasing the number of photons detected by each pixel unit and improving photon detection efficiency while maintaining optical isolation.

The patent transforms the deep trench isolation structure from a harmful element that absorbs and blocks photons into a beneficial photon redirecting element. The protruding portion with its inclined surface causes photons that would otherwise be lost to the isolation structure to be reflected back into the photosensitive area, converting the isolation structure's photon-blocking function into a photon-redistributing function that enhances detection efficiency.

By introducing the vertical protruding portion with an inclined surface, the patent enables the isolation structure to perform a dual function: maintaining optical isolation between pixels while simultaneously reflecting photons back into the photosensitive area. This allows the device to scale with more pixels without proportionally increasing the area lost to isolation structures, as the protruding portions convert previously lost photons into useful detections.

The protruding portion on the deep trench isolation structure performs multiple functions: it maintains optical isolation between adjacent pixel units and simultaneously acts as a reflective element to redirect photons into the photosensitive area. This multi-functionality allows the isolation structure to contribute positively to photon detection rather than merely serving as a passive barrier, improving the ratio of effective photosensitive area to total device area.