Chamber conditioning process development for improved inductively coupled plasma reactive ion etching of GaAs/AlGaAs materials

Dry-etch tool preparation, which is critical to ensuring reproducible etch conditions, is particularly important in multiple-user, multiple-process-tool settings. A reproducible dry-etch process has been developed, utilizing inductively coupled plasma reactive ion etching (ICP-RIE) of GaAs and AlGaAs materials, for the fabrication of ridge structures in slab-coupled optical waveguide semiconductor diode lasers and amplifiers. A commercial ICP-RIE system was used, configured with aluminum-oxide-coated chamber components and a SiCl4/Cl/Ar etch gas mixture. Passivation of etch chamber component surfaces by preconditioning or “seasoning” contributed to a chemically stable etch environment as monitored by tracking the GaAs etch rate. The etched areas and sidewall profiles obtained using this process were smooth, and run-to-run etch depth control was ±2% of the desired target depth of ∼1.25 μm. Energy dispersive analysis x-ray of the etch chamber surfaces before and after chamber conditioning is reported.