Monolithic MEMS Device With Decoupling Trench
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Solution Overview
Problem
The existing process for manufacturing MEMS devices involves complex bonding of three wafers, resulting in a thick and costly product with potential contamination and delamination issues due to the use of multiple semiconductor wafers and gluing materials.
Innovation Solution
A monolithic semiconductor body is used to form both cavities within a single substrate, eliminating the need for bonding multiple wafers and reducing the number of manufacturing steps, thereby simplifying the process and minimizing material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three wafers are bonded together to form MEMS device, then the device can achieve proper structural formation, but the device becomes thick and manufacturing costs increase
Solution Approach 1:
The patent combines multiple wafer functions into a single monolithic semiconductor substrate. The sensitive region, peripheral portion, and both cavities are all formed within one continuous substrate rather than bonding three separate wafers, thereby reducing device thickness while maintaining structural integrity.
Solution Approach 2:
The monolithic substrate is segmented into functional regions including a sensitive region and a peripheral portion, separated by a decoupling trench. This segmentation allows independent optimization of each region while maintaining a thin overall structure.
2Manufacturing precision
If three wafers are bonded together to form MEMS device, then the device can achieve proper structural formation, but manufacturing complexity and costs increase
Solution Approach 1:
The patent merges the functions of three separate wafers into a single monolithic substrate, eliminating the need for complex wafer bonding processes, alignment procedures, and multiple manufacturing steps associated with multi-wafer assembly.
Solution Approach 2:
The single monolithic substrate serves multiple functions that previously required separate wafers: it provides the sensitive region, the peripheral portion, both cavities, and the mechanical support structure, thereby simplifying the manufacturing process.
3Ease of manufacture
If bonding regions and gluing materials are used to fix cap and closing region, then the device can achieve proper assembly, but contamination risks and delamination issues increase
Solution Approach 1:
The patent eliminates the need for separate cap and closing region assemblies by integrating all functional elements directly into the monolithic substrate. This removes the interfaces where bonding regions and gluing materials would be required, thereby eliminating contamination and delamination risks at these interfaces.
4Strength
If sensitive region is connected to peripheral portion, then the device can achieve structural support, but package stress transfers to the sensitive part
Solution Approach 1:
The patent extracts the stress path from the sensitive region by introducing a decoupling trench that separates the sensitive region from the peripheral portion. This allows the peripheral portion to bear package stress independently while the sensitive region remains isolated and protected from stress transfer.
Data Source
AI summary
A micro-electro-mechanical device formed in a monolithic body of semiconductor material accommodating a first buried cavity; a sensitive region above the first buried cavity; and a second buried cavity extending in the sensitive region. A decoupling trench extends from a first face of the monolithic body as far as the first buried cavity and laterally surrounds the second buried cavity. The decoupling trench separates the sensitive region from a peripheral portion of the monolithic body.