Hermetic Microelectronic Package With Dual Cap And ASIC Integration
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Solution Overview
Problem
Conventional microelectronic packages with MEMS transducer structures face challenges in achieving structurally robust and cost-effective designs, particularly in enclosing multiple transducer structures within separate, fluidly-isolated cavities while maintaining optimal pressure conditions and minimizing package size and manufacturing costs.
Innovation Solution
The use of a dual cap architecture where two cap pieces are bonded to a sensor die to create hermetically-sealed cavities with disparate pressures, allowing for the optimization of each MEMS transducer structure, and optionally integrating an ASIC on the cap pieces to reduce the need for a discrete ASIC die, thereby enhancing mechanical strength and reducing package size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If thin film layers are used to produce fluidly-isolated cavities, then manufacturing complexity is reduced, but mechanical strength and seal integrity deteriorate
Solution Approach 1:
The cavity sealing function is segmented from the thin film layer structure and assigned to a separate solid cap piece. The cap piece is bonded to the substrate to form hermetic cavities, while the thin film layers retain only their original sensing functions. This segmentation allows each component to be optimized independently for its specific function.
2Strength
If a dummy cap is bonded over MEMS transducer structures to create hermetic cavities, then mechanical strength improves, but package size and cost increase
Solution Approach 1:
The cap piece is designed to serve multiple functions simultaneously: it provides hermetic sealing for the cavities, serves as a mounting substrate for the ASIC, and acts as a structural reinforcement element. This multi-functionality eliminates the need for separate dummy caps and reduces overall package size.
Solution Approach 2:
The ASIC mounting function is merged with the cavity sealing function by integrating the ASIC directly onto the cap piece. This combination eliminates the need for a separate discrete ASIC die and its associated packaging, thereby reducing package size and component count.
3Reliability
If a dummy cap is used to create hermetic cavities, then seal integrity improves, but manufacturing cost increases
Solution Approach 1:
The cap piece is prepared in advance with integrated ASIC mounting capabilities and bonding structures. The ASIC is mounted on the cap piece before final assembly, allowing for pre-tested, pre-assembled units to be integrated into the final package. This preliminary action reduces assembly steps and manufacturing cost.
4Reliability
If multiple MEMS transducer structures are enclosed in separate hermetic cavities with different pressures, then performance is optimized, but device complexity increases
Solution Approach 1:
The package is segmented into multiple independent hermetic cavities, each enclosing a specific MEMS transducer structure and maintained at its optimal pressure. The cap piece provides common sealing for all cavities, while internal partitions or separate bonding regions maintain fluid isolation between cavities. This segmentation allows independent pressure optimization for each transducer type.
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 results in a structurally robust microelectronic package with reduced size and manufacturing costs, enabling the simultaneous optimization of multiple MEMS transducer structures within separate cavities, while maintaining optimal pressure conditions and integrating additional components like magnetometers for enhanced performance.
Implementation Method 1
two cap pieces positioned on the same side of a sensor die... bonding a solid cap piece lacking active circuitry
Data Source
AI summary
Microelectronic packages having hermetic cavities are provided, as are methods for producing such packages. In one embodiment, the microelectronic package includes a sensor die having first and second Microelectromechanical Systems (MEMS) transducer structures formed thereon. First and second cap pieces are coupled to the sensor die by, for example, direct or indirect bonding. A first hermetic cavity encloses the first MEMS transducer structure and is at least partially defined by the first cap piece and the sensor die. Similarly, a second hermetic cavity encloses the second MEMS transducer structure and at least partially defined by the second cap piece and the sensor die. A vent hole is fluidly coupled to the first hermetic cavity and is sealed by the second cap piece.