FIR Sensor Cap Bonding Before Thinning and Via Etching
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Solution Overview
Problem
The challenge in manufacturing wearable infrared (FIR) sensors is the structural weakening of the substrate during thinning, which can lead to damage and reduced reliability, and the difficulty in integrating T-shaped sensors with electrical contacts into space-constrained wearable devices.
Innovation Solution
A method involving substrate thinning using DRIE techniques, forming vias, and selectively removing cap layer portions to create an inverted T-shape with electrical connections, allowing for precise etching and improved structural integrity, and using a Silicon-On-Insulator (SOI) structure for accurate depth control and uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate is thinned to facilitate faster etching and improve via reliability, then the etching speed and via reliability are improved, but the structural strength of the substrate is weakened leading to damage during manufacture
Solution Approach 1:
The cap layer is formed and bonded to the substrate before the substrate thinning process. This preliminary action provides structural support during the subsequent thinning and via etching operations, preventing substrate damage while enabling the necessary thinning for reliable via formation.
Solution Approach 2:
The cap layer acts as an intermediary protective element between the substrate and the manufacturing process. It reinforces the substrate during thinning and via formation, allowing the substrate to be thinned to optimal thickness without compromising structural integrity during manufacture.
2Adaptability or versatility
If the cap layer is removed to form an inverted T-shape for sealing, then the sealing capability is improved, but the structural integrity during manufacturing is reduced
Solution Approach 1:
The cap layer is formed and bonded to the substrate before the substrate thinning and via formation processes. This preliminary bonding provides the structural reinforcement needed to maintain integrity during manufacturing, while still allowing subsequent removal or thinning of the cap layer to create the inverted T-shape for sealing applications.
Solution Approach 2:
The cap layer processing is segmented into distinct stages: initial formation and bonding for structural support, followed by selective removal or thinning in peripheral regions to create the inverted T-shape. This segmentation allows the cap layer to serve both structural and sealing functions at different manufacturing stages.
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 method enhances the yield of FIR sensors by reducing breakage during manufacturing and enables space-efficient integration of T-shaped sensors with electrical contacts, allowing for precise control over etching depth and placement of vias, facilitating the production of sensors with reduced size windows.
Implementation Method 1
Thinning the substrate may comprise: thinning a backside of the substrate using a DRIE technique.
Implementation Method 2
Bonding the cap layer to the substrate layer may comprise: glass frit bonding the cap layer to the substrate layer.
Implementation Method 3
Bonding the cap layer to the substrate layer may further comprise: bonding the cap layer to the substrate layer in a pressurised atmosphere comprising a predetermined gas at a predetermined pressure.
Data Source
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Figure 3
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AI summary
A method of manufacturing a sensor device(100) comprises forming (200) a substrate (102) comprising a sensor element followed by forming (202) a cap layer (104). The cap layer (104) is then bonded (204) to the substrate (102) before the substrate (102) is thinned (206). A via is formed (210) between the sensor element and a back side of the thinned substrate (102). An electrical connection is provided between the sensor element and the back side of the thinned substrate (102). A mask is formed (208) on the cap layer (104) to define an area about a predetermined window region (108) before forming (210) of the via. A portion of the cap layer (104) about the predetermined window region (108) of the cap layer (104) is removed (212) after formation (210) of the via.