MEMS Cavity Fabrication via Layer Bonding
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Solution Overview
Problem
The manufacturing process for integrated circuits that include MEMS devices designed for different operating environments is complex and costly due to the need for separate fabrication and subsequent combination of components, which increases time and expenses.
Innovation Solution
The integration of MEMS devices within varying pressure operating environments is achieved by forming recesses of different dimensions and materials in a semiconductor wafer, allowing for hermetically sealed cavities with distinct pressures to be created in a single process, using eutectic bonding and fusion bonding techniques, and depositing specific materials to control atmospheric pressure within these cavities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MEMS devices for different operating environments are manufactured separately and then combined, then each device can be optimized for its specific environment, but the fabrication process becomes more complex and costly
Solution Approach 1:
The patent merges multiple MEMS devices designed for different operating environments (vacuum, pressurized, atmospheric) onto a single substrate, allowing them to be fabricated simultaneously in one process rather than separately and combined later. This reduces fabrication complexity while maintaining device optimization through separate cavity sealing.
Solution Approach 2:
The substrate is segmented into multiple isolated cavities, each housing a MEMS device optimized for its specific operating environment. The segmentation is achieved through through-holes that extend through the substrate, allowing individual cavities to be sealed independently after fabrication, thus maintaining reliability while enabling integrated manufacturing.
2Reliability
If MEMS devices for different operating environments are manufactured separately and then combined, then each device can be optimized for its specific environment, but the production time increases
Solution Approach 1:
All MEMS devices for different operating environments are fabricated simultaneously on the same substrate in advance, before the substrate is segmented into individual cavities. This preliminary integrated fabrication significantly reduces production time compared to sequential separate manufacturing and assembly.
Solution Approach 2:
Multiple MEMS devices are combined into a single integrated structure that is fabricated in one process batch, reducing the total fabrication time while maintaining the ability to optimize each device for its specific environment through subsequent cavity sealing.
3Reliability
If MEMS devices for different operating environments are manufactured separately and then combined, then each device can be optimized for its specific environment, but the manufacturing cost increases
Solution Approach 1:
The patent combines multiple MEMS devices onto a single substrate, allowing them to be fabricated simultaneously using shared process steps and materials. This merging approach reduces per-device manufacturing costs while maintaining the ability to optimize each device for its specific operating environment through independent cavity sealing.
Solution Approach 2:
A single substrate serves multiple functions by housing MEMS devices for different operating environments (vacuum, pressurized, atmospheric). This multi-functional substrate approach reduces manufacturing costs by eliminating the need for separate substrates and assembly processes for each device 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 simplifies and reduces the production time and cost by enabling the formation of MEMS devices with varied pressure environments on a single chip, ensuring efficient operation of sensors like gyroscopes and accelerometers within different conditions.
Implementation Method 1
using eutectic bonding and fusion bonding techniques
Implementation Method 2
using eutectic bonding and fusion bonding techniques
Implementation Method 3
depositing specific materials to control atmospheric pressure within these cavities
Data Source
AI summary
A method for forming an integrated circuit having Micro-electromechanical Systems (MEMS) includes forming at least two recesses into a first layer, forming at least two recesses into a second layer, the at least two recesses of the second layer being complementary to the recesses of the first layer. An intermediate layer is bonded onto the second layer, the intermediate layer includes through-holes corresponding to the recesses of the second layer. The first layer is bonded to the intermediate layer such that cavities are formed, the cavities to act as operating environments for MEMS devices. The two cavities have different pressures.