Utilization of optical emission spectroscopy for end-point detection during AlGaAs/GaAs and InGaP/GaAs etching in BCl3/N-2 inductively coupled plasmas

We developed optical emission spectroscopy based end-point detection techni ques for GaAs-based etching in inductively coupled BCl3/Ni-2 plasmas, It wa s found that an emission peak of Ga (417 run) was quite useful as a tracer for in situ process monitoring during both AlGaAs/GaAs and InGaP/GaAs, mult ilayer etching. The intensity of the Ga emission peak increased significant ly during AlGaAs/GaAs etching in a BCl3/N-2 inductively coupled plasma when the GaAs layer was exposed to the plasma. We found the same result with In GaP/GaAs etching. Utilization of the Ga peak signal is very important durin g the plasma process for GaAs-based device fabrication, especially for high electron mobility transistors and heterojunction bipolar transistors in or der to minimize overetch time during the nonselective etching. The techniqu e provides a breakthrough for in situ end-point detection of GaAs-based non selective plasma etching. (C) 2001 The Electrochemical Society.