Hyperspectral Filter Structure With Etch-Stop Layer Control
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Solution Overview
Problem
Existing spectroscopy devices using interference-based filters face challenges in efficiently integrating them with image sensors, particularly CMOS image sensors, due to the need for additional manufacturing steps and the importance of precise layer deposition and thickness uniformity for optimal spectral response.
Innovation Solution
The integration of interference filters, such as Fabry-Pérot filters, with CMOS image sensors is achieved through a method involving deposition of alternating layers with different refractive indices, use of etch stop layers for precise control, and patterned etch processes to form multi-layer interference filter structures, allowing for narrowband filter responses and efficient spectral imaging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If interference-based filters are integrated with CMOS image sensors, then spectral imaging capability is improved, but manufacturing complexity increases due to additional manufacturing steps
Solution Approach 1:
The patent combines the interference filter structure directly with the CMOS image sensor substrate, integrating multiple functional layers (filter layers, stopping layers, sacrificial layers) into a single manufactured component. This merging approach enables spectral imaging capability while consolidating manufacturing steps compared to separate filter and sensor assembly processes.
2Manufacturing precision
If multiple deposition steps are used to create interference filters, then spectral response precision is improved, but manufacturing time increases
Solution Approach 1:
The patent employs stopping layers that are deposited and patterned in advance to define the boundaries and thickness of subsequent filter layers. These pre-positioned stopping layers guide the deposition process, ensuring precise spectral response characteristics while enabling parallel processing and reducing the need for iterative adjustments during manufacturing.
Solution Approach 2:
The interference filter is divided into multiple discrete layers with different refractive indices, where each layer's thickness and position are independently controlled through sequential deposition steps. This segmentation allows precise control over the overall spectral response by optimizing each individual layer's contribution to the interference pattern.
3Reliability
If layer thickness uniformity is strictly controlled, then filter performance is improved, but manufacturing difficulty increases
Solution Approach 1:
The patent introduces stopping layers as intermediary elements between the substrate and the interference filter layers. These stopping layers serve as reference planes that define the thickness of overlying filter layers through controlled deposition. By using these intermediary stopping layers, the system achieves uniform layer thickness and consistent filter performance while simplifying the control requirements for the deposition process.
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 approach enables the creation of small-scale spectral image sensors with improved spectral response performance by ensuring precise layer thickness and deposition, facilitating efficient spectral imaging with localized bandpass responses across different areas of the sensor array.
Implementation Method 1
interference-based filters, such as Fabry-Pérot filters
Implementation Method 2
deposition of alternating layers with different refractive indices
Implementation Method 3
use of etch stop layers for precise control
Data Source
AI summary
A sensor system includes a plurality of optical sensors implemented in a pixel layer of an integrated circuit and a plurality of sets of optical filters implemented proximal to the pixel layer in a plurality of alternating filter layers. An optical filter of a set of optical filters includes a plurality of filter components implemented in a stack and is configured to pass a respective target wavelength range of light to one or more optical sensors of the plurality of optical sensors. One or more filter components of the plurality of filter components in a filter layer of the plurality of filter layers is common to a plurality of optical filters of a set of optical filters.