Stereo laser micromachining of silicon

Abstract

A technique has been developed for 1-μm resolution, high speed micromachining of three-dimensional (3D) silicon parts. The method, based on acousto-optic deflection of laser microchemical chlorine etching reactions, creates parts directly from a file generated with computer-aided design/computer-aided manufacturing (CAD/CAM) software. In this demonstration, 1-μm3 pixels are removed at a rate of 2×104 pixels/s. The laser-driven process relies on one of the fastest-known sustained gas/solid interface reactions, and the size- and pressure-scaling laws permit micromachining at ≳2×105 μm3/s at 10-μm resolution. This is ∼3000 times the rate of current electrodischarge matching methods. Exchange of the etchant gas for organometallic vapor precursors has permitted laser deposition of 3D platinum and cobalt metallization on the laser-etched structures. It is proposed that this approach can satisfy the need for primary patterning of 3D parts and molds for micromechanics, in analogy with two-dimensional (2D) electron-beam patterning of masks for microelectronics.