Micro Mirror Fabrication via Multi-Layer Hard Masks
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Solution Overview
Problem
The stiction between the mirror plate and mechanical stops in micro-mirror arrays of spatial light modulators causes delays in mirror tilt response, affecting the reliability and speed of mirror-based SLM devices, particularly in high-frequency video applications.
Innovation Solution
A method for fabricating micro structures with multiple layers and hard masks over a substrate, allowing for the selective removal of materials to create structure portions of varying heights, including hinge support posts, electrodes, and landing tips, enabling precise tilt movement of mirror plates around hinge components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical stops are used to hold the mirror plate at on and off positions, then the mirror plate can be reliably positioned, but stiction occurs between the mirror plate and mechanical stops causing delay in mirror tilt response
Solution Approach 1:
The patent removes the mechanical stop component entirely from the system. Instead of using physical mechanical stops to hold the mirror plate at on and off positions, the invention uses electrostatic forces generated by electric potential differences between the mirror plate and electrode to position and hold the mirror plate at the desired orientations, thereby eliminating stiction and the associated response time delays while maintaining positioning reliability
Solution Approach 2:
The patent replaces the mechanical stop system with an electrostatic field-based positioning system. The mechanical contact-based positioning mechanism is substituted with an electrostatic force-based mechanism where electric potential differences create electrostatic forces that hold the mirror plate at on and off positions without physical contact, thus eliminating stiction and improving response time
2Manufacturing precision
If multi-layer structures with varying heights are fabricated using conventional methods, then different structure portions can be created, but manufacturing complexity and costs increase
Solution Approach 1:
The patent combines multiple deposition and patterning operations into an integrated fabrication sequence. By depositing multiple layers of material (such as electrode materials, dielectric layers, and reflective coatings) and patterning them in a coordinated manner, the invention creates multi-layer structures with varying heights through a unified process rather than separate discrete steps, thereby reducing manufacturing complexity while maintaining precise height control
Solution Approach 2:
The patent uses vertical layering (adding the height dimension) to create structures of varying heights. By depositing materials in multiple layers with different thicknesses and selectively removing or retaining certain layers in different regions, the invention achieves three-dimensional structures with precise height variations without requiring complex lateral machining or assembly operations
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 reduces manufacturing complexity and costs while enhancing the reliability and speed of mirror tilt movements, improving the performance of micro-mirror arrays in display devices by minimizing stiction and optimizing electrostatic torque.
Implementation Method 1
Each micro mirror can be tilted about an axis by electrostatic forces. The electrostatic forces can be generated by electric potential differences between the mirror plate and an electrode over the substrate underneath the mirror plate.
Implementation Method 2
depositing a first layer of a first material over a substrate; depositing a second layer of a second material over the first layer and the first hard mask
Data Source
AI summary
A method for fabricating a micro structure includes depositing a first layer of a first material over a substrate; patterning a first hard mask over the first layer; depositing a second layer of a second material over the first layer and the first hard mask; patterning a second hard mask over the second layer; and selectively removing the first material and the second material not covered by any of the first mask and the second mask to produce over the substrate the micro structure having a first structure portion having a first height and a second structure portion having a second height.