Fabrication of Multiscale-Structure Wafer-Level Microlens Array Mold

Abstract

The design and manufacture of cost-effective miniaturized optics at wafer level, using advanced semiconductor-like techniques, enables the production of reduced form-factor camera modules for optical devices. However, suppressing the Fresnel reflection of wafer-level microlenses is a major challenge. Moth-eye nanostructures not only satisfy the antireflection requirement of microlens arrays, but also overcome the problem of coating fracture. This novel fabrication process, based on a precision wafer-level microlens array mold, is designed to meet the demand for small form factors, high resolution, and cost effectiveness. In this study, three different kinds of aluminum material, namely 6061-T6 aluminum alloy, high-purity polycrystalline aluminum, and pure nanocrystalline aluminum were used to fabricate microlens array molds with uniform nanostructures. Of these three materials, the pure nanocrystalline aluminum microlens array mold exhibited a uniform nanostructure and met the optical requirements. This study lays a solid foundation for the industrial acceptation of novel and functional multiscale-structure wafer-level microlens arrays and provides a practical method for the low-cost manufacture of large, high-quality wafer-level molds.