VAPOR-PHASE SIO2 ETCHING AND METALLIC CONTAMINATION REMOVAL IN AN INTEGRATED CLUSTER SYSTEM

Vapor phase pregate oxide surface preparation was studied in a high va cuum cluster tool. SiO2 was etched with anhydrous vapor hydrogen fluor ide and methanol vapor. The oxide etch rate can be well controlled by varying wafer temperature, chamber pressure, and gas flow rates. A sta ndard error of 5% in oxide etch rate has been achieved. Particles gene rated are less than ten per 125 mm wafer at an oxide etch rate of 60 A ngstrom/min. Atomic force microscopy measurements reveal no added Si s urface microroughness attributable to vapor hydrogen flouride (HF) etc hing. Trace metallic contaminants such as iron and chromium were reduc ed with UV/Cl-2 based processes. A combination of vapor HF etching fol lowed by UV/Cl-2 metal removal is an effective pregate oxide surface p reparation. (C) 1995 American Vacuum Society.