Abstract

Laser-induced photoelectrochemical (PEC) etching of semiconductor compounds offers the possibility of a maskless, simple-surface patterning process.¹ The thin reaction cell configuration offers some advantages over bulk cells, among which are its ease of use and the potential for a true holographic etching process. In this configuration, an electrolyte layer of about 50 m is held by capillary action between a semiconductor wafer and a microscope cover glass. The cover glass face that is in contact with the electrolyte may be coated with a transparent conductor (such as indium tin oxide) to form one of the biasing electrodes. In previous works²,³ we have suggested that a nonlinear diffusion process governs the PEC reaction; oxide is built and then dissolves during the reaction. We now present findings on light diffraction from an etched pattern in a thin-film cell configuration. We suggest that indirect monitoring of the reaction process, such as light diffraction, be carefully interpreted owing to interfering parameters such as the existence of a reaction product layer.

© 1990 Optical Society of America