Microlens Fabrication via Liquid Crystal Spin Coating
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Solution Overview
Problem
The existing methods for fabricating microlenses and optical waveguides face challenges such as difficulty in maintaining uniformity and preventing merging during the thermal reflow process, especially as design sizes decrease, and the need for thinner microlenses due to increased focal length from additional circuitry, which complicates the control of curvature and temperature requirements.
Innovation Solution
A semiconductor fabricating process involving the formation of a substrate with block structures and an overcoating layer, where the block structures have a controllable aspect ratio, and the overcoating layer is deposited using a scheme like spin-on coating, allowing for adjustable shape and property of the optical elements through parameters like aspect ratio, density, and interfacial properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If thermal reflow process is used to form microlens, then microlens shape can be formed, but microlens merging occurs as design size decreases
Solution Approach 1:
The patent changes the material parameter from polymer to liquid crystal, which has different physical properties including lower operating temperature and different viscosity characteristics. This parameter change allows forming microlenses without high-temperature thermal reflow, thereby preventing merging while maintaining shape uniformity across large areas
Solution Approach 2:
The patent replaces the thermal reflow process (thermal field) with a spin-coating process followed by alignment layer treatment (mechanical and surface field). This substitution eliminates the need for high-temperature heating, thus avoiding the merging issue that occurs with thermal reflow when microlenses are positioned close together
2Manufacturing precision
If thermal reflow process is used to create thinner microlens, then focal length can be adjusted, but process temperature must be much higher which increases merging possibility
Solution Approach 1:
The patent changes the material from polymer to liquid crystal, which fundamentally changes the processing temperature requirement. Liquid crystal materials can be processed at much lower temperatures than polymers, eliminating the need for high-temperature thermal reflow. This allows creating thin microlenses with precise thickness control without the merging risk associated with high-temperature processing
3Ease of manufacture
If hard molding method is used to form microlens, then fabrication is simple, but difficulty in maintaining uniformity across large area
Solution Approach 1:
The patent replaces the hard molding method (mechanical system) with a spin-coating process followed by alignment layer treatment. The spin-coating process naturally provides uniform thickness distribution across large areas due to centrifugal forces, while the alignment layer treatment ensures proper orientation. This combination maintains both fabrication simplicity and high uniformity
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 process enables the precise formation of microlenses and waveguides with controlled curvature and reduced merging issues, accommodating smaller design sizes and varying focal lengths, while maintaining uniformity across large areas.
Implementation Method 1
The over coating is formed over the set of block structures and the substrate by a deposition scheme to form the optical element according to the aspect ratio
Data Source
AI summary
An optical element structure and a fabricating process for the same are provided. The optical element fabricating process includes providing a substrate forming thereon a protrusion; and forming an over coating layer over the protrusion and the substrate by a deposition scheme to form an optical element.