Image Sensor Micro-Lens Gap Fill to Reduce Striation Defects
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Solution Overview
Problem
Current image sensors face challenges in achieving improved image properties and simplified fabrication methods, particularly in the design of color filters and micro-lens layers, which can lead to striation defects and reduced image quality due to non-coplanarity and the need for additional color filters.
Innovation Solution
The proposed image sensor design includes a substrate with pixel regions, color filters, and a micro-lens layer where the micro-lens layer's gap-fill portion contacts the adhesive layer and fills gaps between color filters, eliminating the need for a separate fourth color filter and ensuring coplanar top surfaces of color filters, thereby simplifying fabrication and reducing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fourth color filter is added to fill gaps between color filters, then image quality is improved by reducing striation defects, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines the gap-fill function with the micro-lens layer by forming the micro-lens layer to extend into the gap region between adjacent color filters. This integration eliminates the need for a separate fourth color filter while maintaining the gap-filling function, thus improving image quality without increasing device complexity
Solution Approach 2:
The micro-lens layer is designed to serve multiple functions: it focuses light onto the photodiode and simultaneously fills the gap between color filters to prevent striation defects. This multi-functionality resolves the contradiction by achieving image quality improvement without adding extra structural elements
2Ease of manufacture
If color filters are spaced apart from the lower layer, then ease of manufacture is improved by simplifying fabrication processes, but manufacturing precision may be affected by alignment requirements
Solution Approach 1:
The adhesive layer is formed in advance on the lower layer before placing the color filters. This preliminary action provides pre-defined alignment references that guide the positioning of color filters, thereby maintaining manufacturing precision while allowing spaced-apart configuration that simplifies fabrication
3Reliability
If the micro-lens layer extends to fill gaps between color filters, then image properties are improved by reducing striation defects, but device complexity increases due to extended micro-lens structure
Solution Approach 1:
The gap-fill function is merged with the micro-lens layer formation process. The micro-lens layer is formed to extend into the gap region, combining light-focusing and gap-filling functions into a single structural element, thereby improving image properties without adding separate components
4Reliability
If a fourth color filter is used to fill gaps, then striation defects are reduced, but manufacturing time and cost increase
Solution Approach 1:
The formation of the micro-lens layer is merged with the gap-filling operation. By forming the micro-lens layer to extend into the gap region during the same fabrication process, the patent eliminates the need for a separate fourth color filter, thereby reducing manufacturing steps and improving productivity while maintaining image quality
Solution Approach 2:
The patent extracts and eliminates the unnecessary fourth color filter from the structure. By using the micro-lens layer to fill gaps instead, the design removes redundant components, simplifying the manufacturing process and improving productivity
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
This design enhances image sensor performance by reducing striation defects and improving image properties through the elimination of a fourth color filter, resulting in more reliable photoelectric signals and simplified manufacturing processes.
Implementation Method 1
The photodiode serves to transform or convert incident light into an electrical signal
Implementation Method 2
a micro-lens layer on or covering top surfaces of the color filters
Data Source
AI summary
An image sensor includes a substrate having a plurality of pixel regions, a lower layer on the substrate; a plurality of color filters on the lower layer, and a micro-lens layer on or covering top surfaces of the color filters. The micro-lens layer extends to a location between two of the color filters and contacts the lower layer on one of the pixel regions. The color filters are spaced apart from the lower layer.