Parallel fabrication of high-aspect-ratio all-silicon grooves using femtosecond laser irradiation and wet etching

This paper introduces a simple method using 800 nm femtosecond laser irradiation and wet etching with a hydrofluoric (HF) acid solution for the parallel fabrication of high-aspect-ratio all-silicon groove arrays. In this method, one laser beam was divided into five beams by a diffractive optical element. Five laser-induced structure change (LISC) zones were formed in the silicon simultaneously with a single scan of the divided beams, and then the materials in the LISC zones were etched by HF acid solution to form groove arrays. Via this method, all-silicon grooves with aspect ratios up to 39.4 were produced, and the processing efficiency could be increased by five times in contrast with that of the single laser beam irradiation. Furthermore, high-aspect-ratio grooves with near uniform morphologies were fabricated using this method in silicon wafers with different crystal orientations. (paper)