Journal of Vacuum Science & Technology B, Vol.13, No.4, 1460-1465, 1995
Vapor-Phase SiO2 Etching and Metallic Contamination Removal in an Integrated Cluster System
Vapor phase pregate oxide surface preparation was studied in a high vacuum cluster tool. SiO2 was etched with anhydrous vapor hydrogen fluoride and methanol vapor. The oxide etch rate can be well controlled by varying wafer temperature, chamber pressure, and gas flow rates. A standard error of 5% in oxide etch rate has been achieved. Particles generated are less than ten per 125 mm wafer at an oxide etch rate of 60 Angstrom/min. Atomic force microscopy measurements reveal no added Si surface microroughness attributable to vapor hydrogen flouride (HF) etching. Trace metallic contaminants such as iron and chromium were reduced with UV/Cl-2 based processes. A combination of vapor HF etching followed by UV/Cl-2 metal removal is an effective pregate oxide surface preparation.