Capped Gas Sensor Wafer for Dust-Protected Dicing and Venting
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Solution Overview
Problem
Semiconductor-based sensor devices with micro- and/or nanostructures are sensitive to dust and water during operation and fabrication, which can lead to malfunction and damage.
Innovation Solution
A method for fabricating semiconductor-based sensor devices involves using a capping wafer with gas permeable sections and a protective layer to prevent particles and water from contacting the sensor during division, while allowing gas exchange between the sensor and the environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a capping wafer is attached to protect sensor devices during dicing, then protection from particles and water is improved, but gas exchange between sensor and environment is blocked
Solution Approach 1:
The capping wafer incorporates a porous layer with controlled porosity that allows gas molecules to pass through while blocking larger particles and water droplets. This resolves the contradiction by enabling gas exchange necessary for sensor operation while maintaining protection from harmful contaminants during dicing and operation.
Solution Approach 2:
The capping wafer features localized openings or porous regions positioned specifically over the sensor areas, while other regions remain sealed. This allows gas exchange exactly where needed for sensor function while maintaining protection in other areas, resolving the contradiction through spatial differentiation of functionality.
2Productivity
If conventional dicing with rotating blade is used to divide wafer into individual sensors, then manufacturing efficiency is improved, but particles and water contact the sensor structures
Solution Approach 1:
A protective capping wafer is attached to the sensor wafer before the dicing process begins. This preliminary protective action ensures that when conventional high-speed dicing occurs, the sensor structures are already shielded from particle and water contamination, allowing efficient manufacturing without compromising sensor cleanliness.
3Measurement precision
If waveguide is made partially free hanging to minimize interference effects, then sensor accuracy is improved, but device fragility increases
Solution Approach 1:
The capping wafer acts as a protective shell that spans across and supports the free-hanging waveguide structures. This thin film approach maintains the waveguide's free-hanging configuration for accurate gas interaction while providing mechanical support that prevents fragility issues during handling and operation.
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 method provides protection against dust and water, ensuring the sensor devices operate effectively and are less prone to damage during both fabrication and use.
Implementation Method 1
The capping wafer comprises a porous layer having a porosity between 10% and 80%, viewed from a top surface of the porous layer. The porous layer has a thickness between 1 µm and 100 µm.
Implementation Method 2
The method comprises the steps of applying a protective layer on all porous layers of the capping wafer, dividing the device wafer and the attached capping wafer into individual sensor devices, and removing the protective layer from all porous layers.
Data Source
AI summary
A method for fabricating semiconductor based sensor devices with sensors which are in communication with the environment surrounding the sensor devices, and such a sensor device is described. The method comprises the steps of providing a semiconductor-based device wafer, fabricating a plurality of sensors on the semiconductor-based device wafer, providing a capping wafer, and attaching the capping wafer on the device wafer with each sensor arranged below a recess of the capping wafer. The capping wafer comprises at least one gas permeable section between each recess and the second side, to provide a gas passage between the recess and the environment surrounding the sensor device. The method further comprises the steps of applying a protective layer on all gas permeable sections of the capping wafer, dividing the device wafer and the attached capping wafer into individual sensor devices, and removing the protective layer from all gas permeable sections.