Variable Height Microlens Fabrication for Image Sensor Photosensitivity

The patent applies local quality by creating microlenses with different heights tailored to specific locations. The method uses a photomask with variable thickness to expose the photosensitive layer, resulting in microlenses that have different focal depths at different positions. This local differentiation allows each microlens to focus light at the optimal depth for its specific location, improving photosensitivity while maintaining light focusing capability.

The patent implements parameter changes by varying the height of microlenses across the array. Instead of using a uniform microlens geometry, the invention creates a gradient or varied height profile by controlling the exposure depth through a photomask with variable thickness. This parameter variation allows the focal depth to be optimized for different incident angles, improving light focusing efficiency while maintaining a relatively simple single-step exposure process.

The patent applies preliminary action by pre-configuring the photomask with variable thickness before the exposure process. The photomask is designed in advance with specific thickness variations that correspond to the desired microlens height profile. During exposure, this pre-designed photomask automatically creates microlenses with different heights in a single step, avoiding the need for complex multi-step fabrication processes while achieving optimized photosensitivity.