MEMS Waveguide Etching Depth Deviation via Substrate Segmentation
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Solution Overview
Problem
Existing methods for manufacturing terahertz oscillators face challenges in achieving uniformity and precision during substrate etching, leading to depth deviations and radius of curvature issues, which affect the performance and accuracy of the devices.
Innovation Solution
The approach involves using substrates with different etching depths and employing a method that includes forming specific patterns and bonding techniques, such as thermo-compressive bonding and eutectic-bonding, to create a waveguide structure that minimizes depth deviations and curvature, thereby enhancing the etching quality and precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If deep reactive-ion etching (DRIE) is used to create step heights of 100 to 1,000 μm, then the etching depth increases, but the etching plasma cannot uniformly permeate into the deep step, resulting in poor precision and uniformity
Solution Approach 1:
The substrate is divided into multiple separate substrates, each etched to a moderate depth. These substrates are then bonded together to achieve the total required depth. This segmentation allows each substrate to be etched within the optimal depth range where plasma can uniformly permeate, maintaining high precision and uniformity while achieving deep overall structures.
Solution Approach 2:
Instead of achieving depth in a single substrate through deep etching, the solution transitions to a multi-substrate stacking approach. By adding the dimension of multiple layers bonded together, the patent achieves deep structures without requiring deep etching of individual substrates, thus avoiding plasma permeation issues.
2Length of stationary object
If etching depth increases, then deeper structures are achieved, but etching rate changes with depth, making it difficult to accurately perform etching to a desired depth
Solution Approach 1:
The total etching depth is segmented across multiple substrates. Each substrate is etched to a controlled, achievable depth where etching rate remains relatively stable and predictable. This segmentation enables accurate depth control for each layer while achieving greater total depth through stacking.
Solution Approach 2:
The desired total depth is pre-calculated and divided into manageable segments for each substrate. By planning the etching depth for each substrate in advance based on stable etching rate characteristics, the patent ensures accurate depth control before the actual etching process begins.
3Length of stationary object
If etching depth increases, then deeper structures are achieved, but edges develop a radius of curvature, increasing deviation in depth in the etched bottom surface
Solution Approach 1:
By dividing the structure into multiple substrates with moderate etching depths, each substrate maintains a flatter bottom surface without significant radius of curvature at edges. The stacking of these flat surfaces preserves overall flatness while achieving the required total depth.
4Manufacturing precision
If multiple substrates are bonded together to achieve deep structures, then etching quality improves, but the manufacturing process complexity increases
Solution Approach 1:
While segmentation into multiple substrates improves etching quality, the patent manages process complexity by using standardized bonding procedures and alignment techniques. The repeated use of the same bonding process for each substrate reduces the learning curve and process variability.
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 method improves the evenness of the etched surfaces, allowing for more accurate operation of terahertz oscillators by reducing depth deviations and curvature, leading to improved performance and precision in terahertz frequency operation.
Implementation Method 1
employing a method that includes forming specific patterns and bonding techniques, such as thermo-compressive bonding
Implementation Method 2
employing a method that includes forming specific patterns and bonding techniques, such as thermo-compressive bonding and eutectic-bonding
Data Source
Figure 1~2
Figure 3A~3D
Figure 3E~3G
AI summary
Provided is a microelectromechanical system (MEMS) that includes a first structure 100 and second structure 200. The first structure and second structure may each include a first substrate 110 and a second substrate 120. The first substrate of each structure may have first and second surfaces that face each other. The first substrate may include a via etching hole pattern penetrating the first surface and the second surface and a first non-via etching hole pattern penetrating the first surface. The second substrate 120 of each structure may have third and fourth surfaces that face each other. The second substrate may include a second non-via etching hole pattern penetrating the third surface in a position corresponding to the via etching hole pattern of the first substrate. In the microelectromechanical system (MEMS) the second surface of the first substrate and the third surface of the second substrate may be bonded together.