Glass MEMS Comb Structure With Variable Etching Radius Control
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Solution Overview
Problem
The LIDE method for etching glass substrates is limited by the inability to modify the etching radius spatially resolved, resulting in fixed edge profiles and constraints on the formation of micromechanical comb structures with desired properties.
Innovation Solution
The method involves applying laser pulses to define the outer contour of fingers with continuous tool trajectories, followed by wet-chemical anisotropic etching, allowing precise control over the etching radius and sidewall scalloping to create monolithic glass-based MEMS with improved micromechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the LIDE method is used to etch glass substrates with fixed etching radius, then the manufacturing process is simple and cost-effective, but the manufacturing precision of micromechanical comb structures is limited
Solution Approach 1:
The patent applies local quality by varying the pulse spacing parameter locally along the tool trajectory to achieve spatially resolved etching radius control. Different sections of the comb structure receive different pulse spacing, creating the desired non-uniform etching radius profile without changing the fundamental LIDE process or requiring additional equipment.
Solution Approach 2:
The patent changes the pulse spacing parameter of the laser processing to control the etching radius. By adjusting the pulse spacing between laser pulses along the tool trajectory, the etching radius is modified spatially, enabling precise control of the comb structure geometry while maintaining the simplicity of the LIDE method.
2Manufacturing precision
If laser pulses are applied with constant pulse spacing, then the manufacturing process is simple, but the manufacturing precision of comb structure contours is insufficient
Solution Approach 1:
The patent introduces dynamics by transitioning from constant to variable pulse spacing along the tool trajectory. The pulse spacing is dynamically adjusted based on the local geometric requirements of the comb structure contour, enabling high-precision fabrication of complex shapes while maintaining a relatively simple programming approach.
Solution Approach 2:
The patent applies preliminary action by pre-calculating and programming the variable pulse spacing values before the actual laser processing. This allows the complex variable spacing pattern to be prepared in advance, making the actual manufacturing process straightforward and maintaining ease of manufacture while achieving high contour precision.
3Adaptability or versatility
If wet-chemical etching is used with fixed etching radius, then the process is cost-effective and simple, but the adaptability for different micromechanical structures is limited
Solution Approach 1:
The patent applies preliminary action by pre-modifying the glass substrate with laser pulses arranged in specific patterns before the wet-chemical etching step. This preliminary laser modification creates a mask pattern that guides the subsequent etching, enabling the fabrication of various micromechanical structures with a single etching process and maintaining process simplicity.
Solution Approach 2:
The patent applies local quality by creating spatially varying laser modification patterns on the glass substrate before etching. Different regions receive different laser pulse densities and arrangements, which then translate into different etching behaviors in the wet-chemical step, enabling diverse structure fabrication with a single unified 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 production of high-performance MEMS with efficient, cost-effective, and homogeneous micromechanical properties, suitable for electrostatic actuators and sensors, without the need for additional substrates or masks, and allows for precise control over the comb structure's response and actuation.
Implementation Method 1
laser-induced modification of the glass substrate and subsequent wet-chemical anisotropic etching
Implementation Method 2
subsequent wet-chemical anisotropic etching
Data Source
AI summary
In order to extend the possible applications of the already known LIDE (laser-induced deep etching) method, this invention provides for producing a micromechanical comb structure (25) by placing a plurality of laser pulses (4) on a glass substrate (3) with a subsequent wet-chemical etching step for exposing the comb structure (25), and to precisely control the position of those laser pulses (4) that define the outer contour (6) of respective fingers (24) of the comb structure (25). This makes it possible to form very narrow fingers (24) that have uniform sidewalls (13), whereby very small gap dimensions (35) and uniform electrostatic actuation of the comb structure (25) are rendered possible. By controlling the phase angle φ and/or the extent of the sidewall scalloping of the fingers (24), it is also possible to favorably influence or set, in a targeted manner, the mechanical properties of the comb structure (25).