Silicon Spatial Light Modulator with Hidden Hinge for High Fill Ratio
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Solution Overview
Problem
Conventional spatial light modulators face challenges in increasing the number of micro-mirrors while maintaining array dimension size, as reducing mirror size poses design and manufacturing issues due to current materials and fabrication processes.
Innovation Solution
A method and structure for fabricating a spatial light modulator with a high fill ratio, utilizing an all silicon mirror, torsion spring hinge, and multi-level electrode design, which includes a semiconductor substrate, silicon hinge, and mirror structure that can operate at higher temperatures and maintain reliability, with improved bonding areas and reduced bonding tolerances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the size of individual micro-mirrors is decreased to increase the number of micro-mirrors in the array, then the array dimension size remains constant, but design and manufacturing problems arise due to current materials and fabrication processes
Solution Approach 1:
The patent changes the material parameter from conventional materials to silicon-based materials (silicon nitride, silicon oxide, silicon), which enables better manufacturing precision at smaller dimensions. This material parameter change allows the micro-mirrors to be fabricated with improved accuracy while maintaining the high density required for increased quantity.
Solution Approach 2:
The patent employs composite material structures combining silicon nitride, silicon oxide, and silicon layers to create the micro-mirror and hinge structures. This composite approach provides both mechanical support and precise dimensional control, resolving the manufacturing precision issues that arise when decreasing mirror size to increase array density.
2Quantity of substance
If additional micro-mirrors are added to the array while maintaining conventional size, then the number of micro-mirrors increases, but the silicon real estate used increases
Solution Approach 1:
The patent changes the size parameter of individual micro-mirrors to smaller dimensions, which allows more micro-mirrors to be packed into the same silicon real estate area. This parameter change enables increased array density without proportionally increasing the total silicon area required.
3Quantity of substance
If the mirror size is decreased to maintain constant array dimension, then more micro-mirrors can be fitted, but stiction forces increase and reliability decreases
Solution Approach 1:
The patent uses composite material structures (silicon nitride, silicon oxide, silicon) that provide superior mechanical properties compared to conventional materials. These materials have better stiction characteristics and maintain reliability even when mirror dimensions are reduced, allowing high-density arrays without the reliability penalties that would result from simply scaling down conventional designs.
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 a spatial light modulator with a high fill ratio and hidden hinge, providing long-term reliability, increased operational temperature range, and improved image quality, while reducing stiction forces and manufacturing complexities.
Implementation Method 1
a hinge device (116) including a silicon material... a mirror structure (130) including a post region (136) coupled to the hinge device (116) and a mirror plate (130) coupled to the post region (136)
Implementation Method 2
When a voltage is applied to an electrode array, an electrostatic attraction force acts on the mirror plate to rotate it to a first position
Implementation Method 3
a hinge device (116) including a silicon material... a mirror structure (130) including a post region (136) coupled to the hinge device (116)
Data Source
AI summary
A display system includes a light source and a first optical system coupled to the light source and adapted to provide an illumination beam along an illumination path. The display system also includes a spatial light modulator positioned in the illumination path. The spatial light modulator includes a semiconductor substrate including a plurality of electrode devices and a hinge structure coupled to the semiconductor substrate. The hinge structure includes silicon material. The spatial light modulator also includes a mirror post coupled to the hinge structure and extending to a predetermined distance from the semiconductor substrate and a mirror plate coupled to the mirror post and overlying the plurality of electrode devices. The display system further includes a second optical system coupled to the spatial light modulator and adapted to project an image onto a projection surface.