Carbon Nanotube Pillars for Uniform LCoS Cell Gaps
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Solution Overview
Problem
Conventional liquid crystal on silicon (LCoS) chips face challenges in achieving uniform cell gap spacing, leading to non-uniform optical images and color shifts due to uneven spacer dimensions, which affects the quality and yield of micro-display devices.
Innovation Solution
The integration of carbon nanotube (CNT) pillars grown on the glass substrate serves as spacers, providing precise control over cell gap uniformity and acting as electrical conductors to connect the voltage source with the ITO layer, eliminating the need for conventional connectors and enhancing alignment through nano-LCoS alignment keys.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spacers are used to define cell gap, then cell gap spacing can be established, but non-uniform spacer dimensions cause non-uniform cell gap and optical defects
Solution Approach 1:
The patent changes the material parameter from conventional spherical or cylindrical spacers to carbon nanotube pillars, which have superior dimensional uniformity and mechanical properties. The CNT pillars maintain consistent height and diameter throughout, eliminating the non-uniform cell gap spacing that causes optical defects.
Solution Approach 2:
The patent uses a stamping process to create multiple identical CNT pillar structures simultaneously. The stamp imprints uniform patterns across the substrate, ensuring consistent cell gap dimensions across the entire display area, thereby preventing optical rings and color shifts.
2Manufacturing precision
If CNT pillars are used as spacers, then cell gap uniformity is improved, but additional manufacturing steps are required
Solution Approach 1:
The patent combines multiple functions into the CNT pillars: they serve as both spacers for cell gap definition and as alignment structures through integrated alignment keys. The alignment keys are formed as part of the same stamping process that creates the CNT pillars, reducing the need for separate alignment component fabrication and assembly steps.
Solution Approach 2:
The CNT pillars with integrated alignment keys provide self-alignment functionality during the assembly process. The alignment keys automatically guide the positioning of substrates relative to each other, eliminating the need for complex external alignment mechanisms or additional alignment steps.
3Reliability
If conventional ITO connectors are used for electrical connection, then voltage can be applied to ITO layer, but connector components and assembly steps are required
Solution Approach 1:
The patent merges the electrical connection function directly into the CNT pillar structure. The CNT pillars, being electrically conductive, provide both mechanical support as spacers and electrical pathways to the ITO layer, eliminating the need for separate ITO connector components and their associated assembly steps.
Solution Approach 2:
The CNT pillars serve multiple functions simultaneously: they act as spacers for cell gap definition, provide structural support, enable alignment through integrated keys, and conduct electricity to the ITO layer. This multi-functionality reduces the overall component count and simplifies the device structure.
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 ensures high-quality optical images by maintaining uniform cell gaps and improving manufacturing yield, reducing optical rings and color shifts, and allowing for precise adjustment of CNT pillar height to suit specific applications.
Implementation Method 1
The CNT pillars are grown on the glass substrate portion by the conventional chemical vapor deposition technique.
Implementation Method 2
acting as electrical conductors to connect the voltage source with the ITO layer
Data Source
AI summary
A nano-liquid crystal on silicon (nano-LCoS) chip having carbon nanotube (CNT) pillars that are grown on a glass substrate thereof. As the heights of the CNT pillars are uniform, the CNT pillars can function as spacers providing a uniform cell gap between the glass substrate and a silicon chip of the nano-LCoS chip. Also, being excellent electrical conductors, CNT pillars can form a part of the electrical connection between an outside voltage source and the indium tin oxide (ITO) layer formed on the glass substrate. The nano-LCoS chip includes nano-LCoS alignment keys that are formed in the silicon chip and connected to the CNT pillars. By applying the same voltage to the ITO layer and keys, a portion of the liquid crystal activated by the keys become transparent fiduciary marks for optical alignment of nano-LCoS chips.