Sacrificial Substrate for MEMS Etching and Separation
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Solution Overview
Problem
Conventional methods for forming MEMS with piezoelectric actuators face challenges in achieving uniformity of structure dimensions, leading to inconsistent performance, particularly in forming features within micrometer precision, and require manual handling which is tedious and prone to damage during substrate separation.
Innovation Solution
A method involving fusion bonding of silicon substrates with a sacrificial substrate, allowing for precise etching and separation using a mechanical device with sensors to control pressure, ensuring uniformity and preventing damage during the separation process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods are used to form MEMS structures, then the manufacturing process is simpler, but the manufacturing precision and uniformity of structure dimensions deteriorate
Solution Approach 1:
The invention divides the substrate into a device substrate and a sacrificial substrate that can be separated. The sacrificial substrate is used during processing to provide support and enable precise etching, then removed to release the final MEMS structure. This segmentation allows for higher manufacturing precision during fabrication while simplifying the overall process by enabling batch processing of multiple structures simultaneously.
Solution Approach 2:
The sacrificial substrate acts as an intermediary during the fabrication process. It provides mechanical support to the device substrate during etching and processing, enables precise dimensional control, and is subsequently removed to release the final structure. This intermediary approach allows for high precision manufacturing without requiring complex specialized equipment for each individual structure.
2Reliability
If manual handling is used during substrate separation, then the process is simpler, but the reliability and risk of damage increase
Solution Approach 1:
The sacrificial substrate serves as a mediator that facilitates controlled separation. By designing the sacrificial substrate with specific properties (thickness, material composition), the separation process can be automated with controlled force application, reducing manual handling and associated damage risks while maintaining process simplicity.
Solution Approach 2:
The invention changes physical parameters of the sacrificial substrate (thickness, material properties) to enable controlled separation. By optimizing these parameters, the separation force can be precisely controlled to prevent damage to the device substrate, allowing for reliable automated separation processes.
3Manufacturing precision
If features are formed without a sacrificial substrate, then the process is more direct, but the manufacturing precision and feature dimension control worsen
Solution Approach 1:
By segmenting the processing into phases using a sacrificial substrate, the invention enables precise feature formation during the supported phase, then releases the final structure after sacrificial material removal. This segmentation allows for micrometer-level precision in feature dimensions while maintaining ease of manufacture through standardized processing steps.
Solution Approach 2:
The sacrificial substrate provides preliminary support during critical fabrication steps, enabling precise feature formation before the final structure is released. This preliminary action ensures manufacturing precision during etching and processing, while the sacrificial substrate can be removed using straightforward procedures that maintain ease of manufacture.
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
Enables the formation of MEMS with high thickness uniformity and precise feature dimensions, improving performance consistency and automating the substrate separation process, reducing the risk of damage and human error.
Implementation Method 1
The bonding can include creating Van der Waals bonds between the first silicon substrate and the sacrificial silicon substrate and can occur at room temperature
Data Source
AI summary
A method of etching a silicon substrate is described. The method includes bonding a first silicon substrate to a sacrificial silicon substrate. The first silicon substrate is etched. A pressure is applied at an interface of the first silicon substrate and the sacrificial silicon substrate to cause the first silicon substrate to separate from the sacrificial silicon substrate. An apparatus having metal blades can be used to separate the substrates.