Wafer-Level Mid-IR Gas Sensor Packaging With Hermetic Reference Cavity
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Solution Overview
Problem
Current gas sensors are expensive and bulky, making them costly to manufacture and less reliable, which is a challenge for widespread adoption in applications like environmental monitoring and smart home systems.
Innovation Solution
A monolithic fluid sensor system is developed using a fusion-bond or wafer-bond based wafer-level package that integrates a thermal radiation emitter, optical filter, waveguide, and detector on a semiconductor substrate, with a reference sensor arrangement in a hermetically sealed cavity for improved accuracy and cost-effectiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional gas sensors are used, then gas detection function is achieved, but manufacturing cost is high and device size is large
Solution Approach 1:
The patent merges multiple sensor components (emitter, optical filter, waveguide, detector) onto a single semiconductor substrate to form an integrated sensor arrangement. This integration reduces the number of discrete components, simplifies assembly, lowers manufacturing cost, and improves reliability by reducing connection points that could fail.
Solution Approach 2:
The patent transitions from traditional bulky gas sensor designs to a planar two-dimensional integration layout on a semiconductor substrate. This dimensional change enables compact packaging, reduces device size, and allows for scalable manufacturing processes that lower costs while maintaining or improving performance.
2Productivity
If sensor components are integrated on a single substrate, then manufacturing cost decreases and reliability improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent incorporates alignment marks and positioning structures during the substrate fabrication process itself, before the actual sensor components are assembled. This preliminary action establishes precise reference frames that guide subsequent assembly steps, ensuring accurate positioning of optical components without requiring complex real-time alignment procedures.
Solution Approach 2:
The patent utilizes standard semiconductor manufacturing process parameters and materials that are compatible with existing fabrication capabilities. By designing the sensor arrangement to work within established process tolerances and using conventional materials, the patent achieves high precision integration without requiring breakthrough manufacturing techniques.
3Measurement precision
If a hermetically sealed cavity is created for the reference sensor, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent combines the reference sensor arrangement with the main sensor arrangement on the same semiconductor substrate, sharing common structural elements and packaging features. This integration reduces the overall package complexity compared to having separate hermetically sealed reference and measurement sensors, while still providing the accuracy benefits of a controlled reference environment.
Solution Approach 2:
The semiconductor substrate serves multiple functions: it acts as the mechanical support structure, the optical platform for the sensor components, and the hermetic seal when bonded to the cover substrate. This multi-functionality reduces the need for additional specialized components, simplifying the overall device structure while maintaining measurement accuracy.
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 solution provides a cost-effective, reliable, and efficient mid-infrared gas sensor system with enhanced sensitivity and resolution, allowing for precise gas concentration measurement while minimizing environmental influences.
Implementation Method 1
the first main surface region of the cover substrate is bonded (fusion bonded - wafer bonded) to the first main surface region of a sensor substrate
Implementation Method 2
a sensor arrangement having a thermal radiation emitter, an optical filter structure, a waveguide structure and a thermal radiation detector
Data Source
AI summary
A monolithic fluid sensor system includes a sensor arrangement and a reference sensor arrangement that are monolithically arranged, wherein respective substrates or semiconductor substrates (wafers or semiconductor wafers) are bonded (fusion bonded or wafer bonded on wafer-level) to each other for providing the resulting monolithic fluid sensor system. The monolithic fluid sensor system particularly includes the sensor arrangement, a cover substrate, the reference sensor arrangement, and a reference cover substrate.