MEMS Cavity Sealing via Deposition Plug
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Solution Overview
Problem
Current methods for hermetically sealing MEMS pressure sensor devices, such as eutectic and fusion bonding, face challenges including increased device package height, stress-induced deflections, and susceptibility to temperature variations, which affect accuracy and increase costs.
Innovation Solution
A method involving a semiconductor structure where a MEMS substrate is bonded to a CMOS substrate using a fusion bond, with a cavity sealed by forming a plug or sealing layer over a vent hole using a film deposition device set to a reference pressure, reducing the reference pressure and package height while minimizing stress and costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If eutectic or fusion bonding methods are used to hermetically seal MEMS pressure sensor devices, then sealing reliability is improved, but device package height increases and stress-induced deflections occur
Solution Approach 1:
The patent extracts the sealing function from traditional bonding methods (eutectic/fusion bonding) and implements it through a different mechanism: forming a seal layer within a cavity that hermetically seals the MEMS device. This eliminates the need for thick bonding layers, thereby reducing device package height while maintaining sealing reliability.
Solution Approach 2:
The patent introduces a seal layer as an intermediary element within the cavity that performs the hermetic sealing function. This seal layer acts as a mediator between the cavity walls, providing reliable sealing without requiring the thick structures associated with traditional bonding methods, thus reducing overall device height.
2Reliability
If eutectic or fusion bonding methods are used to hermetically seal MEMS pressure sensor devices, then sealing reliability is improved, but stress-induced deflections and temperature variation susceptibility increase
Solution Approach 1:
The patent removes the stress-inducing bonding process from the sealing mechanism. By extracting the sealing function and implementing it through a seal layer formed within the cavity using deposition techniques, the method eliminates the thermal stress and mechanical stress associated with eutectic and fusion bonding, thereby reducing stress-induced deflections and temperature variation susceptibility.
Solution Approach 2:
The patent replaces the mechanical bonding process (eutectic/fusion bonding involving heat and pressure) with a deposition-based sealing mechanism. The seal layer is formed through vapor deposition or similar processes, substituting the high-stress mechanical bonding system with a low-stress conformal coating approach, which minimizes stress-induced deflections and improves temperature stability.
3Reliability
If traditional bonding methods are used for hermetic sealing, then sealing reliability is improved, but manufacturing costs increase
Solution Approach 1:
The patent extracts the sealing function from expensive bonding processes and implements it through more cost-effective deposition techniques. By removing the need for eutectic or fusion bonding equipment and processes, the method reduces manufacturing costs while maintaining hermetic sealing reliability through the seal layer approach.
Solution Approach 2:
The patent employs a seal layer that can be formed through relatively inexpensive deposition processes compared to bonding operations. The seal layer serves as a cost-effective sealing solution that eliminates the need for expensive bonding equipment, materials, and process control, thereby reducing overall manufacturing costs while achieving reliable hermetic sealing.
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 reduces the reference pressure in the hermetic cavity, decreases the device package height, lowers costs, and enhances the flexibility in packing MEMS devices, while minimizing the impact of temperature variations on device performance.
Implementation Method 1
forming a plug or sealing layer over the vent hole with a film deposition device
Data Source
AI summary
A method for manufacturing a microelectromechanical systems (MEMS) device is provided. According to some embodiments of the method, a semiconductor structure is provided. The semiconductor structure includes an integrated circuit (IC) substrate, a dielectric layer arranged over the IC substrate, and a MEMS substrate arranged over the IC substrate and the dielectric layer to define a cavity between the MEMS substrate and the IC substrate. The MEMS substrate includes a MEMS hole in fluid communication with the cavity and extending through the MEMS substrate. A sealing layer is formed over or lining the MEMS hole to hermetically seal the cavity with a reference pressure while the semiconductor structure is arranged within a vacuum having the reference pressure. The semiconductor structure resulting from application of the method is also provided.