Focused Ga ion beam etching characteristics of GaAs with Cl2

Abstract

The etching characteristics of GaAs bombarded with 20 keV Ga+ ion beam during impingement of Cl2 gas flux have been investigated. At room temperature, an etch yield (the number of substrate atoms removed per ion) with showered ion beam irradiation approaches a saturated value of 101 atoms/ion with the increase in gas flux for different incident ion fluxes of the order of 1014 ions/s/cm2. A previously proposed etching model which accounted well for the experimental results for Si/Cl2 is in good agreement with the present results. Variation of etch depth computed by this model for focused ion beam raster scanning also agrees with the experimental results. However, as the substrate temperature rises up to 110 °C, the etch yield increases as opposed to the case of Si/Cl2 and the saturated etch yield becomes 430 atoms/ion. It seems that formation of several layers of chlorinated compounds might be responsible for the increase in etch yield. Finally, fabrication of multineedle field electron emitter is demonstrated.