MEMS Wafer Alignment via Segmented Fabrication
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Solution Overview
Problem
Achieving precise alignment between two chips in micro-electro mechanical systems (MEMS) devices is challenging, limiting design flexibility and manufacturing efficiency.
Innovation Solution
The method involves forming MEMS transducers from two wafers, decoupling the thickness of the proof mass and flexures to allow independent design, and etching both sides of the wafers for optical alignment, enabling the formation of a single chip with enhanced processing speed and design benefits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If two chips are wired together to form MEMS devices, then device functionality is achieved, but alignment precision deteriorates
Solution Approach 1:
The patent divides the MEMS device into two separate wafers (first wafer and second wafer) that can be independently fabricated and then bonded together. This segmentation allows each wafer to be optimized separately for its specific function (proof mass on first wafer, flexures on second wafer) while maintaining precise alignment through the bonding process, thereby resolving the contradiction between device functionality and alignment precision.
Solution Approach 2:
The patent introduces an intermediary bonding process between the two wafers that enables precise alignment. The bonding interface acts as a mediator that allows the two separately fabricated wafers to be joined with high precision, overcoming the alignment difficulties that would arise from trying to wire two chips together while maintaining their individual design optimizations.
2Adaptability or versatility
If proof mass and flexures are integrated in a single wafer, then manufacturing is simplified, but design flexibility deteriorates
Solution Approach 1:
The patent segments the proof mass and flexures onto different wafers (proof mass on first wafer, flexures on second wafer), allowing independent design optimization for each component. This segmentation enables different materials, thicknesses, and geometries to be used for each component without compromising manufacturing, thereby achieving both design flexibility and manufacturing simplicity through separate fabrication processes followed by bonding.
Solution Approach 2:
The patent transitions from a single-wafer three-dimensional integration to a multi-wafer stacked architecture. By moving to another dimension (stacking wafers vertically), the patent achieves independent design of proof mass and flexures while maintaining manufacturing simplicity through standardized wafer fabrication and bonding processes.
3Volume of moving object
If wafer thickness is reduced for miniaturization, then device size is decreased, but structural integrity deteriorates
Solution Approach 1:
The patent segments the structural functions between two separate wafers, allowing each wafer to be optimized for its specific structural requirements. The first wafer can be designed with appropriate thickness and material properties for the proof mass, while the second wafer can be optimized for flexure structural integrity, thereby achieving miniaturization without compromising overall structural strength.
Solution Approach 2:
The patent effectively creates a composite structure by bonding two different wafers together, where each wafer can be made from materials and thicknesses optimized for its specific function. This composite approach allows the overall device to be miniaturized while maintaining structural integrity through the combined strength of the bonded wafer assembly.
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 allows for improved alignment and independent design of proof mass and flexures, increasing sensitivity and control over movement detection in multiple axes, enhancing the overall performance of MEMS devices.
Implementation Method 1
both sides of the wafers being etched for optical alignment
Data Source
AI summary
Embodiments of a micro electro mechanical system are disclosed.