Etch Dispersion System for High Aspect Ratio MEMS Cavities
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Solution Overview
Problem
Existing methods for forming micro-electromechanical systems (MEMS) sensors and devices face challenges in fully separating moveable elements from cavity walls, leading to nonfunctioning devices due to high costs and limited etch speed, especially in small-scale features.
Innovation Solution
An etch dispersion system is introduced, comprising dispersion apertures and channels in the substrate to facilitate efficient removal of sacrificial layers, allowing etch materials to penetrate and disperse effectively, thereby separating moveable elements from cavity walls.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional etch methods are used to remove sacrificial material, then the process is simple, but the etch speed is limited and separation of moveable elements from cavity walls is insufficient
Solution Approach 1:
The etch dispersion system divides the substrate into multiple segments with individual channels and apertures, allowing parallel etching operations across different regions. This segmentation enables simultaneous access to multiple sacrificial material locations, dramatically increasing overall etch speed while maintaining manageable system complexity through modular design
Solution Approach 2:
The invention transitions from conventional surface-level etching to three-dimensional etching by forming channels that extend vertically through the substrate thickness. This dimensional change allows etch material to reach sacrificial material at multiple depth levels simultaneously, achieving complete separation of moveable elements from cavity walls in a single processing step
2Reliability
If existing CMOS process techniques are used, then cost is reduced, but moveable elements stick to cavity walls and devices become nonfunctioning
Solution Approach 1:
The etch dispersion system is formed as part of the substrate structure before the sacrificial material is fully deposited and before moveable elements are created. This preliminary formation of channels and apertures ensures that etch material can access and remove sacrificial material completely, preventing sticking issues before they occur and ensuring reliable separation
Solution Approach 2:
The channels and apertures act as intermediaries that facilitate the transport of etch material from the substrate surface to the sacrificial material located within the substrate. This intermediary structure ensures complete penetration and removal of sacrificial material, achieving reliable separation while maintaining compatibility with existing CMOS manufacturing processes
3Area of stationary object
If conventional etching is used, then the process is straightforward, but the area covered is limited and separation is incomplete
Solution Approach 1:
The substrate is divided into multiple etching zones, each with its own channel-aperture system. This segmentation allows parallel processing across large substrate areas, dramatically increasing the total etched area covered per unit time while maintaining complete separation of moveable elements across the entire substrate surface
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 efficient and effective etching of large areas, improving the separation of moveable elements and enhancing the functionality of MEMS devices by increasing etch speed and reducing costs.
Implementation Method 1
an etch material... accessing the sacrificial layer by the etch material via at least one aperture formed in the substrate... removing a portion of the sacrificial layer by the etch material
Data Source
AI summary
Embodiments relate to structures, systems and methods for more efficiently and effectively etching sacrificial and other layers in substrates and other structures. In embodiments, a substrate in which a sacrificial layer is to be removed to, e.g., form a cavity comprises an etch dispersion system comprising a trench, channel or other structure in which etch gas or another suitable gas, fluid or substance can flow to penetrate the substrate and remove the sacrificial layer. The trench, channel or other structure can be implemented along with openings or other apertures formed in the substrate, such as proximate one or more edges of the substrate, to even more quickly disperse etch gas or some other substance within the substrate.