Image Sensor Color Filter Layout to Prevent Edge Spot Defects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image sensors often experience image failure due to spots generated at the edge portion of the active pixel region during the manufacturing process, particularly during the rinsing and drying processes when components of the developing solution and color filter layer mix in the rinsing solution.
Innovation Solution
The image sensor design includes a substrate with distinct regions, where active pixels are in the first region and optical black (OB) pixels are in the second region. A dummy color filter layer is formed on the light blocking metal pattern in the second region adjacent to the first region, which helps in preventing spots from forming at the edge of the active pixel region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a color filter layer is formed and rinsing process is performed during manufacturing, then the color filter layer is completed, but spots are generated at the edge portion of the active pixel region causing image failure
Solution Approach 1:
A dummy color filter layer is introduced as an intermediary structure between the active pixel region and the optical black pixel region. This dummy layer serves as a buffer that prevents rinsing solution from accumulating at the edge of the active pixel region, thereby eliminating spot formation while maintaining the functionality of the color filter layer in the active region.
Solution Approach 2:
The dummy color filter layer is formed in advance on the optical black pixel region before the final rinsing and drying processes. This preliminary structure preparation ensures that when the rinsing solution is applied, there is already a defined boundary structure in place to guide the solution flow and prevent it from reaching the active pixel region edges.
2Area of stationary object
If the active pixel region is maximized to improve image sensing area, then more light can be detected, but spots are more likely to form at the edges during manufacturing
Solution Approach 1:
The pixel region is segmented into distinct zones: the active pixel region for image sensing, the optical black pixel region for light blocking, and the dummy color filter layer region that acts as a transition zone. This segmentation allows the active pixel region to be maximized while the dummy layer provides a protective buffer zone that prevents manufacturing defects from affecting the active region.
Solution Approach 2:
The dummy color filter layer serves as an intermediary buffer zone between the active pixel region and the optical black pixel region. This intermediate structure absorbs the harmful effect of rinsing solution accumulation, protecting the active pixel region edges from spot formation while allowing the active region to maintain its maximum area.
Data Source
AI summary
An image sensor includes a substrate including a first region and a second region surrounding the first region, a light sensing element in the substrate, a planarization layer on the light sensing element, a color filter array layer including color filters on the planarization layer on the first region of the substrate, a light blocking metal pattern on the planarization layer on the second region of the substrate, a dummy color filter layer on the light blocking metal pattern on a portion of the second region adjacent to the first region of the substrate, and microlens on the color filter array layer. Active pixels are in the first region, and optical black (OB) pixels are in the second region.