<title>Characteristics of gate oxide surface material after exposure to magnetron-enhanced reactive ion etching plasma</title>

Abstract

New developments in the area of etching are focused on an etch system/process that has similar results to RIE (such as anisotropy and high selectivity to the underlying layer) while operating at lower DC biases. This is to minimize the charge build up on the gate structure and minimize the substrate damage during the plasma etch process. Magnetron Enhanced Reactive Ion Etching (MERlE) has the advantage of lowering the DC bias as the magnetic field increases while maintaining acceptable etch rates for throughput requirements. A low DC bias results in a lower charge build up on the gate structure during the plasma etch process. The use of the Magnetic Field in MERlE also increases etch rates by increasing the density of the ionized species. In this study the plasma exposed oxide surface composition and thickness after an HBR/C12 based polysilicon etch and after various surface treatment/cleaning processes is investigated by Auger Electron Spectroscopy (AES) and Scanning Ion Mass Spectroscopy (SIMS). The Chlorine and Bromine impingement into the top surface of the gate oxide as determined by AES and SIMS analysis was correlated to the etch rate of this layer in a dilute Hydroflouric acid solution. The effect of process variation in a low pressure low power MERlE HBr/Cl/He/O2 chemistry on the poly to oxide selectivity total gate oxide loss and thickness of the plasma exposed oxide is also studied in this