MEMS Anchor Structure Using Relaxed Epitaxial Layers
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Solution Overview
Problem
The manufacture of MEMS devices faces challenges in creating anchors that are strong enough to support moving elements while minimizing footprint and avoiding mechanical failure, which increases the complexity and cost of the devices.
Innovation Solution
The solution involves forming anchors using a semiconductor substrate with an intermediate layer and a device layer, where the intermediate layer is relaxed with zero or very low strain by growing it beyond its critical thickness, and the device layer is also relaxed using similar epitaxial growth techniques, allowing for the creation of strong yet compact anchor structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the anchor is made stronger to support the moving element under stress, then the strength increases, but the footprint and complexity increase
Solution Approach 1:
The patent employs a multi-layer composite structure consisting of a first layer, second layer, and third layer with different material properties. The first layer provides mechanical strength, the second layer provides structural support, and the third layer provides stress distribution, creating a composite anchor that achieves high strength with reduced footprint compared to monolithic anchors.
Solution Approach 2:
The patent transitions from planar anchor designs to three-dimensional multi-layer structures. By stacking multiple layers vertically, the anchor gains increased strength and stress-bearing capacity without proportionally increasing the lateral footprint, effectively utilizing the vertical dimension to resolve the strength-footprint contradiction.
2Strength
If the anchor design is made more complex to increase strength, then the strength increases, but the manufacturing complexity and cost increase
Solution Approach 1:
The anchor is segmented into multiple functional layers, each with specific purposes. This segmentation allows each layer to be optimized for its particular function while maintaining overall simplicity in the manufacturing process, as each layer can be deposited using standard semiconductor fabrication techniques.
Solution Approach 2:
The multi-layer anchor structure serves multiple functions simultaneously: mechanical support, stress distribution, and structural integrity. This multi-functionality is achieved through a standardized fabrication process that deposits different material layers, each contributing to one or more functions, thereby reducing overall device complexity despite the enhanced capabilities.
3Area of stationary object
If the anchor footprint is reduced to minimize device size, then the area decreases, but the strength and reliability decrease
Solution Approach 1:
The patent uses composite multi-layer materials that provide high strength-to-area ratio. The combination of different materials in the first, second, and third layers creates synergistic effects that maintain or enhance anchor strength while reducing the required footprint compared to single-material anchors of equivalent strength.
Solution Approach 2:
By utilizing vertical stacking of multiple layers, the patent compensates for reduced lateral footprint through increased vertical complexity. The multi-layer structure distributes stresses across multiple interfaces and layers, maintaining structural integrity and strength even when the horizontal footprint is minimized.
4Reliability
If the anchor is made more robust to prevent mechanical failure, then the reliability increases, but the footprint and complexity increase
Solution Approach 1:
The multi-layer composite structure enhances reliability by distributing mechanical stresses across multiple layers and interfaces, preventing stress concentration that leads to failure. Each layer is designed to specific material properties that contribute to overall structural robustness, achieving high reliability with minimized footprint.
Solution Approach 2:
The vertical multi-layer architecture provides redundant load paths and stress distribution mechanisms that enhance reliability. When stress is applied, it is distributed across multiple layer interfaces rather than concentrated in a single plane, preventing catastrophic failure while maintaining a compact footprint.
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 enables the creation of MEMS devices with anchors that are stronger under stress while maintaining a small footprint, thereby reducing the complexity and cost of the devices and minimizing the risk of mechanical failure.
Implementation Method 1
growing an intermediate layer by epitaxy overlying a semiconductor substrate
Implementation Method 2
growing a device layer by epitaxy overlying the intermediate layer
Data Source
AI summary
A semiconductor device is disclosed having one or more anchors that is configured to support a moving mass. The one or more anchors are formed in or on the semiconductor substrate. The one or more anchors are attached to the semiconductor substrate. An intermediate layer is formed overlying the semiconductor substrate. A device layer is formed overlying the intermediate layer. The device layer, the intermediate layer, and the semiconductor substrate are single crystal. The moving mass is formed in the device layer. The at least one anchor comprises a dielectric material coupled to the semiconductor substrate. The moving mass couples to the at least one anchor. Portions of the intermediate layer are removed to free the moving mass in relation the semiconductor substrate.