Microlens Array Fabrication With Adjustable Sagittal Height
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Solution Overview
Problem
Traditional microlens array manufacturing methods are cumbersome, have low process consistency and reliability, and are limited by small lens sagittal height.
Innovation Solution
A method involving direct production of a working mold without a master mold, using plasma deep silicon etching to form grooves, applying and softening a photoresist layer to create a concave surface, and forming a microlens array through adhesive attachment or PDMS injection, allowing adjustment of lens sagittal height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional master mold method is used, then microlens array can be manufactured, but the manufacturing process becomes cumbersome and complex
Solution Approach 1:
The invention extracts and eliminates the master mold step from the traditional manufacturing process. By directly forming the working mold on the substrate using spin-coating and thermal reflow methods, the complex two-step mold process is simplified to a single-step process, directly addressing the contradiction between ease of manufacture and device complexity
Solution Approach 2:
The invention merges the master mold formation and working mold formation into a single integrated process. The photoresist layer is directly patterned and thermally reflowed to create the final microlens array structure, combining multiple traditional steps into one streamlined process that reduces complexity
2Reliability
If traditional master mold method is used, then microlens array can be manufactured, but process consistency and reliability are low
Solution Approach 1:
The invention removes the master mold and working mold separation, eliminating the need for mold flipping operations. The direct formation of lenses on the substrate eliminates intermediate transfer steps that compromise process consistency and reliability
Solution Approach 2:
The photoresist layer is pre-patterned with microlens patterns before thermal reflow, ensuring precise positional accuracy is established early in the process. This preliminary patterning action guarantees consistent lens positioning and orientation without requiring subsequent mold flipping operations
3Manufacturing precision
If photoresist coating thickness is limited, then manufacturing is simpler, but lens sagittal height becomes small
Solution Approach 1:
The invention changes the photoresist coating thickness parameter from traditional thin coatings to thick coatings (50-200 μm). This parameter change enables the formation of microlenses with sufficient sagittal height (10-50 μm) while maintaining manufacturing simplicity through the spin-coating and thermal reflow process
Solution Approach 2:
The thick photoresist layer provides localized material volume where needed for lens formation. The thermal reflow process then redistributes this material to create the desired lens curvature and sagittal height, achieving precise local optical properties while maintaining overall process simplicity
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
Reduces process complexity and cost, enhances lens sagittal height, and expands application range by controlling etching depth and photoresist thickness.
Implementation Method 1
step S5, softening the photoresist layer so that it adheres to the inner wall of the groove to form a concave smooth surface
Implementation Method 2
UV curing the adhesive material, separating the second substrate from the working mold, and forming a microlens array on the surface of the second substrate
Data Source
AI summary
A method for fabricating a microlens array includes: step S1, providing a first substrate, and forming a patterned mask layer on the first substrate; step S2, etching the first substrate to form spaced grooves; step S3, removing the patterned mask layer; step S4, attaching a photoresist layer to the upper surface of the first substrate; step S5, softening the photoresist layer so that it adheres to the inner wall of the groove to form a concave smooth surface; step S6, solidifying the photoresist layer to form a working mold; applying an adhesive material and the working mold through the second substrate. The microlens array is produced by pressing the mold together or injecting PDMS material into the surface of the working mold.