Image Sensor Microlens Air Regions Optical Path
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Solution Overview
Problem
Conventional CMOS image sensors experience light loss and reduced quantum efficiency due to the architecture, which includes a microlens and optical filter that lengthens the optical path, and also face issues with cross-talk between pixels.
Innovation Solution
The proposed solution involves forming a stuffed material with air regions on the microlenses, allowing for a shorter optical path and improved light transmission efficiency, and optionally incorporating a shelter around the microlenses to reduce cross-talk, with the stuffed material being filled using chemical vapor deposition or other processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the conventional architecture with microlens and optical filter is used, then the optical path is lengthened, but light loss increases and quantum efficiency decreases
Solution Approach 1:
The patent repositions the optical filter from a horizontal layer above the microlens to a vertical structure on the side wall of the microlens. This dimensional change shortens the optical path length while maintaining the filter's light filtering function, thereby reducing light loss and improving quantum efficiency.
Solution Approach 2:
The patent changes the physical state and position of the optical filter from a planar layer to a vertical side-wall structure. This parameter change in the filter's geometry and location optimizes the optical path, reducing light loss while preserving the filtering capability.
2Ease of manufacture
If the optical filter height is reduced to lower manufacturing costs, then manufacturing cost decreases, but light transmission efficiency may be compromised
Solution Approach 1:
By moving the optical filter to the vertical side wall of the microlens, the patent achieves a compact structure that reduces the overall height without compromising light transmission efficiency. This dimensional reconfiguration allows cost-effective manufacturing while maintaining optical performance.
3Loss of energy
If the microlens structure is optimized to improve quantum efficiency, then quantum efficiency increases, but cross-talk between pixels may increase
Solution Approach 1:
The patent applies different functional properties to different parts of the microlens structure. The side wall contains the optical filter for light gathering and filtering, while the top surface maintains light gathering capability. This local differentiation improves quantum efficiency while the side-wall configuration helps contain light within individual pixel regions, reducing cross-talk.
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 configuration enhances quantum efficiency by optimizing light transmission and reduces manufacturing costs by lowering the optical filter height, while also minimizing cross-talk between pixels.
Implementation Method 1
the stuffed material is filled on the microlenses by utilizing a chemical vapor deposition process
Implementation Method 2
The microlens 130 is used for gathering an incident light 150
Implementation Method 3
The optical filter 120 is disposed between the substrate 110 and the microlens 130, and utilized for filtering the incident light 150
Data Source
AI summary
A fabricating method of an image sensor includes the steps of: providing a substrate; forming sensing elements on the substrate; forming microlenses on the sensing elements; filling a stuffed material on the microlenses, and air regions are formed in the stuffed material; and forming optical filters on the stuffed material.