Inductively coupled plasma reactive ion etching of GaAs wafer pieces with enhanced device yield

Inductively coupled plasma reactive ion etching (ICP-RIE) is used in the fabrication of GaAs slab-coupled optical waveguide (SCOW) laser and amplifier devices in order to prepare etched-ridge-waveguide surface features. The processing of GaAs wafer pieces (less than full wafers) requires mounting these samples on a ceramic or silicon carrier wafer by means of a thermally conductive mounting paste to improve thermal contact between the GaAs and carrier wafer. However, use of a mounting paste requires additional postetch handling of samples, including mechanical clean-up and multiple solvent cleaning steps. Insufficient paste removal can lead to unwanted surface contamination and film adhesion issues during subsequent sample processing. Massachusetts Institute of Technology Lincoln Laboratory has developed an ICP-RIE process for GaAs wafer pieces that eliminates the use of mounting paste. This process features time-limited thermal management during etching, which is essential to maintain predictable etch rates along with suitable etched surfaces and satisfactory sidewall quality. Utilizing this simplified etch process for SCOW fabrication has resulted in greatly reduced film adhesion failures and a dramatic improvement in device yield. (C) 2014 American Vacuum Society.