Tension Breaking Features for Recessed Color Filter Arrays
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Solution Overview
Problem
Conventional recessed color filter arrays in imaging devices often exhibit non-uniform thickness, leading to uneven pixel output signals and increased fixed pattern noise due to surface tension issues during filter material flow, which affects imaging efficiency and microlens alignment.
Innovation Solution
Incorporating tension breaking features, such as trenches and walls, around the color filter array recess to break the surface tension of the filter material during formation, thereby reducing the settling distance and achieving a more uniform thickness across the array.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a recessed color filter array is formed without tension breaking features, then the stack height requirement is met, but the filter array thickness becomes non-uniform with increased settling distance
Solution Approach 1:
The recessed region is segmented by introducing tension breaking trenches that divide the continuous filter material flow path. These trenches create separate flow zones that prevent surface tension from causing material to pile up at the recess edges, thereby achieving uniform thickness while maintaining the recessed configuration for stack height compliance.
Solution Approach 2:
Tension breaking structures (trenches and walls) are introduced as intermediary elements between the filter material and the recessed region edges. These intermediaries break the surface tension continuity, preventing the material from being pulled toward the edges by capillary forces, thus achieving uniform thickness deposition.
2Manufacturing precision
If tension breaking features are added to the recessed color filter array, then the filter array thickness uniformity is improved, but the device complexity increases
Solution Approach 1:
The tension breaking features segment the recessed region into controlled flow zones. By strategically placing trenches and walls at specific locations, the design achieves thickness uniformity without requiring complex three-dimensional structures, thereby minimizing the increase in device complexity while maximizing the benefit to manufacturing precision.
Solution Approach 2:
Tension breaking features are applied locally at critical locations where surface tension effects are most pronounced (at the recess edges and corners) rather than throughout the entire structure. This localized application achieves the necessary thickness uniformity while minimizing the overall structural complexity and material usage.
3Ease of manufacture
If the filter material flows into the recess without tension breaking features, then the production process is simple, but fixed pattern noise and shading effects increase
Solution Approach 1:
Tension breaking trenches and walls serve as intermediary structures that modify the filter material flow behavior during deposition. These features are integrated into the existing production process without requiring additional complex manufacturing steps, thereby maintaining ease of manufacture while effectively reducing fixed pattern noise and shading effects by ensuring uniform thickness.
Solution Approach 2:
The tension breaking features are pre-formed in the substrate before filter material deposition. This preliminary action prepares the surface to control material flow and prevent surface tension-induced thickness variations, thereby eliminating the need for complex post-processing steps and maintaining production simplicity while reducing harmful effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The implementation of tension breaking features results in a more uniform color filter array thickness, reducing fixed pattern noise and shading effects, and providing a stable foundation for microlenses, thereby enhancing imaging efficiency.
Implementation Method 1
one problem associated with formation of a conventional recessed color filter array 14 is that the color filter array 14 may have a non-uniform thickness and may be thicker at the edges of the color filter array 14 than at the center. The majority portion of the color filter array 14 located away from the edge of the recess 12 is formed to a relatively uniform thickness d. The distance from the edge of the recess 12 to the portion of the color filter array 14 at the relatively uniform thickness d is known as the settling distance s.
Data Source
AI summary
A method of making a color filter array of an imaging device comprises forming a main recess for a color filter array, forming a tension breaking feature at an edge of the main recess, and providing a color filter array material across the tension breaking feature and main recess as part of forming the color filter array. The tension breaking feature reduces the settling distance of the color filter array material. An imaging device having the thus formed color filter array is also described.