High Aspect Ratio MEMS Through Holes via Substrate Segmentation
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Solution Overview
Problem
The manufacturing of MEMS devices faces challenges in increasing the aspect ratio of through holes in semiconductor wafers, limiting the thickness and complexity of MEMS structures due to process capabilities, which restricts the formation of larger and more complex MEMS devices.
Innovation Solution
A substrate structure and method for fabricating semiconductor structures with through holes having an aspect ratio greater than 30, achieved by forming multiple sub-through holes that are substantially aligned to create a single through hole, allowing for increased thickness and complexity of MEMS structures, such as springs and proof masses, while using techniques like deep reactive-ion etching and bonding processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the aspect ratio of through holes in semiconductor wafers is increased to allow thicker MEMS structures, then the thickness and complexity of MEMS devices can be improved, but the process capability is exceeded and manufacturing becomes infeasible
Solution Approach 1:
The through hole is divided into multiple sub-through holes formed in separate substrates that are stacked together. Each substrate contains a portion of the sub-through holes, and when bonded, these sub-through holes align to form the complete high aspect ratio through hole. This segmentation allows the manufacturing process to work with lower aspect ratios in each individual substrate while achieving the overall high aspect ratio structure.
Solution Approach 2:
Multiple substrates containing sub-through holes are stacked and bonded together in a nested configuration, with each substrate contributing a segment of the final through hole structure. The sub-through holes in each substrate are positioned to align with corresponding sub-through holes in adjacent substrates, creating the complete through hole pathway when the substrates are bonded together.
2Length of stationary object
If multiple sub-through holes are formed in separate substrates and stacked to create high aspect ratio through holes, then the thickness of MEMS structures can be increased, but the alignment complexity and device complexity increase
Solution Approach 1:
The sub-through holes are formed in each substrate before the substrates are bonded together. This preliminary formation of sub-through holes in separate substrates allows for easier manufacturing with lower aspect ratios, and the subsequent bonding process simply requires alignment of these pre-formed features rather than creating the entire high aspect ratio through hole in a single complex process step.
3Quantity of substance
If aggressive design rules are implemented to increase IC device density, then the density of integrated circuits can be improved, but the complexity of processing semiconductor devices with decreased feature sizes increases
Solution Approach 1:
The fabrication process is segmented into multiple manageable steps involving separate substrates, each processed to a certain degree before bonding. This segmentation of the manufacturing process makes it more manageable and less complex than attempting to process a single thick substrate with high aspect ratio through holes in one continuous process.
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 structures with enhanced thickness and complexity, satisfying next-generation requirements without the need for complex alignment mechanisms, thereby improving the efficiency and capability of MEMS device fabrication.
Implementation Method 1
techniques like deep reactive-ion etching and bonding processes
Implementation Method 2
techniques like deep reactive-ion etching and bonding processes
Data Source
AI summary
The present disclosure provides a substrate structure for a micro electro mechanical system (MEMS) device. The substrate structure includes a cap and a micro electro mechanical system (MEMS) substrate. The cap has a cavity, and the MEMS substrate is disposed on the cap. The MEMS substrate has a plurality of through holes exposing the cavity, and an aspect ratio of the through hole is greater than 30.