Utilization of Optical Emission Spectroscopy for End-Point Detection during AlGaAs/GaAs and InGaP/GaAs Etching in BCl[sub 3]/N[sub 2] Inductively Coupled Plasmas

Abstract

We developed optical emission spectroscopy based end-point detection techniques for GaAs-based etching in inductively coupled BCl 3 /N 2 plasmas. It was found that an emission peak of Ga ͑417 nm͒ was quite useful as a tracer for in situ process monitoring during both AlGaAs/GaAs and InGaP/GaAs multilayer etching. The intensity of the Ga emission peak increased significantly during AlGaAs/GaAs etching in a BCl 3 /N 2 inductively coupled plasma when the GaAs layer was exposed to the plasma. We found the same result with InGaP/GaAs etching. Utilization of the Ga peak signal is very important during the plasma process for GaAs-based device fabrication, especially for high electron mobility transistors and heterojunction bipolar transistors in order to minimize overetch time during the nonselective etching. The technique provides a breakthrough for in situ end-point detection of GaAs-based nonselective plasma etching.