Curved Micromirrors via Sacrificial Layer Segmentation
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Solution Overview
Problem
Existing digital micromirror devices are complex and costly to manufacture, with low manufacturing yield, due to their intricate structures and high complexity.
Innovation Solution
A method involving the formation of micromirrors with curved surfaces, using sacrificial layers to create pivotally movable micromirrors with convex or concave reflective surfaces, which are hinged to a transparent layer, allowing for improved manufacturing efficiency and reduced complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional intricate structures are used for micromirrors, then manufacturing complexity increases, but manufacturing yield decreases and costs increase
Solution Approach 1:
The micromirror structure is segmented into distinct functional layers: a curved substrate providing the base geometry, a hinge layer enabling pivotal movement, and a reflective layer providing optical functionality. This segmentation allows each layer to be optimized independently and simplifies the overall manufacturing process by breaking down the complex structure into manageable components that can be fabricated using standard semiconductor processing techniques.
Solution Approach 2:
The substrate is pre-formed with the desired curved geometry (convex or concave) before subsequent layers are added. This preliminary action of shaping the substrate first eliminates the need for complex post-fabrication shaping operations, thereby reducing overall device complexity while maintaining manufacturing precision. The curvature is established early in the process when it can be most efficiently achieved through standard deposition and etching techniques.
2Reliability
If complex micromirror structures are manufactured, then functional performance is achieved, but manufacturing yield is low
Solution Approach 1:
The hinge structure is designed to automatically provide the pivotal movement function through its elastic properties, eliminating the need for additional actuation mechanisms. The curved substrate geometry inherently provides the mechanical advantage needed for mirror deflection, allowing the structure to serve its own functional needs without external complexity. This self-service approach ensures reliable functionality while maintaining simple, high-yield manufacturing processes.
3Illumination intensity
If traditional micromirror designs are used, then light reflection control is achieved, but manufacturing costs are high
Solution Approach 1:
The reflective layer is deposited as a uniform, homogeneous coating over the entire curved substrate surface using standard semiconductor deposition techniques. This homogeneous approach ensures consistent optical properties across all micromirrors in the array, providing reliable light reflection control. The uniformity is achieved through controlled deposition parameters that ensure even material distribution, eliminating the need for costly post-fabrication optical coating operations.
Solution Approach 2:
The curved substrate structure serves multiple functions simultaneously: it provides the mechanical base for the micromirror, defines the optical curvature for light reflection control, and acts as one of the electrodes for actuation. This multi-functionality eliminates the need for separate components for each function, thereby reducing manufacturing complexity and cost while maintaining effective light reflection control across the micromirror array.
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
The solution enables the production of micromirrors with enhanced manufacturing yield and reduced costs, while maintaining the ability to produce high-quality grayscale and color images through precise light reflection control.
Implementation Method 1
Each mirror many measure less than 1⁄5 of the width of a human hair and corresponds to one pixel in a projected image. The digital micromirror device chip can be combined with a digital video or graphic signal, a light source, and a projector lens so that the micromirrors reflect an all-digital image onto a screen or onto another surface.
Data Source
AI summary
A method comprising providing a first substrate and forming a first sacrificial layer over the first substrate, the first sacrificial layer comprising a curved surface portion, and forming a curved micromirror by depositing a reflective material over at the curved surface portion.