Fabrication of a diamond-based imprint mold by applying diamond CVD on silicon master molds for a glass microlens array

A diamond-based mold could be fabricated for glass imprinting by applying a replica method using CVD diamond film growth on a precisely patterned Si master substrate with arrays of square-arranged microlens (10 × 10 μm2 in size). After the hot filament chemical vapor deposition (CVD) process, the diamond mold was obtained through dissolution of the Si substrate. The surface roughness (RMS) of the diamond mold could be drastically decreased from 52.9 nm to 0.5 nm by using the post reactive ion etching (RIE) process with fluorocarbon gases as well as by lowering the film deposition temperature. We evaluated the morphology of the diamond mold pattern from our cross-sectional observations by focused ion beam (FIB) etching, and we examined the crystal structure of the mold via Raman scattering spectroscopy. Fabrication of glass microlens array devices was demonstrated by imprinting the fabricated diamond-based mold on a soda-lime silicate glass and a quartz glass. We also characterized the mold releasability and its shape transcription properties.

Research highlights
► Diamond molds with maximum height of 6 μm for glass imprinting could be fabricated.
► Microlens arrays could be fabricated by imprinting the diamond mold on quartz glass.
► The imprinted quartz glass has the shape of the microlens array with maximum depth of 5 μm.