Ion Beam Assisted Maskless Etching of GaAs by 50 keV Focused Ion Beam

Maskless etching of GaAs by means of an ion beam assisted etching technique has been investigated using a 50 keV focused Au beam, and it is found that ion beam assisted etching is very promising for maskless direct etching with a high etching rate. The Au+ focused beam was irradiated on GaAs in chlorine ambient gas. It was observed that this etching technique gives a smooth etched surface with an etching rate of 2 µm·min-1·mA-1·cm2, which is about 100 times larger than the value observed for physical sputter etching without chlorine gas. From the measurement of mass spectra it was observed that about 75 percent of chlorine gas reacts with residual water vapour and HCl gas is produced. It is considered that both chlorine and HCl gases play an important role in the enhancement of etching.