Laser micromachining of high-aspect-ratio metallic grooves for application to microthermal devices

Abstract

A fabrication method of high-aspect-ratio (HAR) microgrooves in stainless steel using laser-induced thermochemical wet etching is reported in this paper. The fabrication of deep microgrooves with an aspect ratio over 10 is realized by applying a multiple etching process with an optimization of process conditions. The cross-sectional profile of the microgrooves can be adjusted between rectangular and triangular shapes by properly controlling laser power and etchant concentration. An excellent dimensional uniformity is achieved among the grooves with little heat affected area. Microgrooves with a width ranging from 15 to 50 µm can be fabricated with an aspect ratio of 10 and a pitch of 150 µm or smaller. The effects of process variables such as laser power, scan speed and etchant concentration on the fabrication results including etch width, depth and cross-sectional profile are closely examined.