Excimer Laser Etching Process of CdTe Crystals for Formation of Deep Vertical Trenches

Deep isolation trenches with high aspect ratio were formed on CdTe crystals using the excimer laser etching technique. Vertical trenches 80-μm deep and 55-μm wide were formed in 5 min by irradiating a laser on the CdTe crystal through a contact-type metal mask in vacuum. Surface chemistry of the laser-irradiated CdTe crystal was examined by Auger electron spectroscopy (AES), scanning electron microscopy (SEM), and photoluminescence (PL) to determine the extent of laser-induced damage. It was found that the damaged layer remains confined to the thin surface layer in the submicron range, which could be easily removed by a light Br-methanol etch.