Deep InP Gratings for Opto-Electronic Devices Etched by Cl₂/CH₄/Ar Inductively Coupled Plasma

Deep InP gratings are etched by Cl₂/CH₄/Ar inductively coupled plasma (ICP) at room temperature. A comparison is made between SiN_x mask patterns formed by wet and dry etching. SF₆ reactive ion etching is adopted for smooth and vertical sidewall. The etching conditions of Cl₂/CH₄/Ar ICP are optimized for high anisotropy, and a 1.7-μm-deep InP grating with an aspect ratio of 10:1 is demonstrated. The technique is then used for the fabrication of 1.55-μm laterally coupled distributed feedback AlGaInAs-InP laser.