Design and Fabrication of Wafer-Level Microlens Array with Moth-Eye Antireflective Nanostructures

Abstract

Wafer-level packaging (WLP) based camera module production has attracted widespread industrial interest because it offers high production efficiency and compact modules. However, suppressing the surface Fresnel reflection losses is challenging for wafer-level microlens arrays. Traditional dielectric antireflection (AR) coatings can cause wafer warpage and coating fractures during wafer lens coating and reflow. In this paper, we present the fabrication of a multiscale functional structure-based wafer-level lens array incorporating moth-eye nanostructures for AR effects, hundred-micrometer-level aspherical lenses for camera imaging, and a wafer-level substrate for wafer assembly. The proposed fabrication process includes manufacturing a wafer lens array metal mold using ultraprecise machining, chemically generating a nanopore array layer, and replicating the multiscale wafer lens array using ultraviolet nanoimprint lithography. A 50-mm-diameter wafer lens array is fabricated containing 437 accurate aspherical microlenses with diameters of 1.0 mm; each lens surface possesses nanostructures with an average period of ~120 nm. The microlens quality is sufficient for imaging in terms of profile accuracy and roughness. Compared to lenses without AR nanostructures, the transmittance of the fabricated multiscale lens is increased by ~3% under wavelengths of 400–750 nm. This research provides a foundation for the high-throughput and low-cost industrial application of wafer-level arrays with AR nanostructures.

Coupled Superhydrophilic PMMA Film with Inverted Pyramid Microstructures for Antireflection and Antifogging Properties

“…On the one hand, air will enter the nanoparticle layer, which declines the refractive index of the top layer, and a lower refractive index contributes to augmenting transmission of the film [22,23]. On the other hand, the optical properties of the film are affected by the interlayer particle structure [24]; the granular structure of the top layer not only causes the incident light to be scattered at different angles, but also concentrates the incident light. The incident light preferentially penetrates the film, which improves the light transmittance of the C-P film.…”

Single-Step Fabrication of Longtail Glasswing Butterfly-Inspired Omnidirectional Antireflective Structures

“…To resolve the issues, a spinning-shear-force-induced assembly technology has recently been developed to rapidly produce wafer-sized non-close-packed colloidal monolayers using a standard spin-coater [ 25 ]. The shear-aligned colloidal crystals can be utilized to design and build moderate-aspect-ratio (~1) antireflective structures [ 26 , 27 ]. Unfortunately, their antireflection performances are impaired at large viewing angles.…”

Nanopatterned Polymer Molds Using Anodized Aluminum Templates for Anti-Reflective Coatings

“…Recent studies have demonstrated several methodologies to fabricate moth-eye nanostructures including the Langmuir-Blodgett technique [12], lithography [9,13,14], imprinting processes [15], double replication of a silicon master [10], dip-coating solid silica nanoparticles [11], and a combination of ultrasonic vibration demolding and precision hot embossing [16]. In particular, there has been a series of studies on the AAO templateassisted synthesis of moth-eye-inspired nanostructures reporting significant properties such as superhydrophobicity [17], anti-reflectivity [18,19], and ultrasensitive substrates for surface-enhanced Raman scattering-based detection [4,20].…”