Temperature dependence of neutral and positively charged Si and SiCl etch products during argon-ion-enhanced etching of Si(100) by Cl2

Abstract

The temperature dependence of neutral and positively charged Si and SiCl etch products produced during argon-ion-enhanced etching of Si(100) in a molecular-chlorine background are measured over a temperature range between 323 and 923 K. The neutral Si and SiCl product fluxes, detected by laser ionization mass spectroscopy, undergo a monotonic decrease in intensity with increasing temperature. A model based on the temperature dependence of the molecular chlorine sticking probability successfully explains the observed results. In contrast to the neutral species, the yields of the positively charged etch products, Si+ and SiCl+, exhibit a more complex temperature dependence. The ion yields first decrease with increasing temperature, then increase to a maximum at approximately 800 K. As the temperature is further increased to 923 K, both ionic products rapidly decrease. The initial decrease in ionic products mimics the decrease in the neutral products and is likely to be due to the decreasing sticking coefficient of molecular chlorine. A second mechanism, possibly the changing electronic properties of the silicon substrate with increasing temperature, is required to explain the local maximum in the product yield at 800 K.