Dummy Pixel Micro-Lens Alignment for Image Sensor Shading Control

The patent introduces dummy pixels with micro-lenses during the fabrication process before the actual imaging pixels are completed. These dummy pixels serve as test structures to measure overlay accuracy and alignment precision in advance, allowing manufacturers to detect and correct alignment issues before they affect the main imaging pixels. This preliminary measurement approach resolves the contradiction by enabling quality control without compromising the optical performance of the final product.

The patent extracts the measurement function from the main imaging pixel array and implements it separately in dedicated dummy pixel regions. These dummy pixels are specifically designed for measuring shading variations and overlay accuracy, separate from the imaging pixels that capture actual images. This separation allows the measurement function to be added without increasing the complexity of the imaging pixel structure, resolving the contradiction between measurement precision and device complexity.

The patent applies different micro-lens configurations to different pixel regions: dummy pixels have shifted micro-lenses optimized for measuring overlay accuracy, while imaging pixels have centered micro-lenses optimized for optical performance. This local differentiation allows each region to have the specific structural characteristics needed for its function, resolving the contradiction between measurability of overlay accuracy and structural uniformity by making uniformity conditional on the functional requirements of each pixel type.