Auto Focus Pixel Grid Width Layout for Image Sensor Cross-Talk
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Solution Overview
Problem
Image sensors experience degradation in auto focus function due to cross-talk phenomena, which reduce the sensitivity difference between phase difference detection regions and deteriorate the auto focus performance.
Innovation Solution
The image sensor incorporates a grid structure with varying widths near auto focus pixel regions, spaced from the central region of the pixel array, to reduce cross-talk and enhance auto focus performance by adjusting the grid structure's width as it moves away from the central region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grid structure with uniform width is used across the pixel array, then the manufacturing process is simple, but cross-talk occurs between adjacent pixels causing degradation of auto focus function
Solution Approach 1:
The grid structure is designed with varying widths at different locations: narrower grid portions adjacent to auto focus pixel regions and wider grid portions elsewhere. This local differentiation reduces cross-talk in critical auto focus regions while maintaining structural integrity and simplifying manufacturing in non-critical areas, thereby resolving the contradiction between auto focus reliability and device complexity.
2Use of energy by moving object
If the grid structure is placed close to the central region of the pixel array, then light incidence efficiency is maximized, but cross-talk between adjacent pixels increases
Solution Approach 1:
The grid structure implements location-dependent width variations: in regions closer to the central pixel array where light incidence efficiency is critical, the grid portions are optimized to balance light transmission and cross-talk reduction, while in peripheral regions, wider grid portions provide stronger isolation. This spatially differentiated design resolves the contradiction between maximizing light incidence efficiency and minimizing cross-talk.
3Object-affected harmful factors
If wider grid portions are used throughout the pixel array, then cross-talk is reduced, but light incidence efficiency and sensitivity decrease
Solution Approach 1:
The grid structure uses narrower grid portions specifically adjacent to auto focus pixel regions where sensitivity is critical, while employing wider grid portions in other areas where cross-talk reduction is prioritized. This selective width variation maintains high sensitivity in auto focus regions while effectively reducing cross-talk in non-critical regions, resolving the contradiction between cross-talk reduction and sensitivity preservation.
Data Source
AI summary
An image sensor includes: a chip structure including normal pixels and auto focus pixels; a grid structure disposed on the chip structure; and color filter regions defined by the grid structure over the chip structure. The color filter regions include normal filter regions and auto focus filter regions. The normal filter regions correspond to the normal pixels. The chip structure includes a first region at a first distance, and a second region a second distance greater than the first distance. The auto focus filter regions include a first auto focus filter region on the first region and a second auto focus filter region on the second region. A first width of a first grid portion disposed adjacent the first auto focus filter region among the grid structure is narrower than a second width of a second grid portion disposed adjacent the second auto focus filter region among the grid structure.