Low pressure chemical vapor deposition of oxide from SiH4/O 2: Chemistry and effects on electrical properties
Abstract
The low pressure chemical vapor deposition (CVD) process of SiO2 from SiH4 and O2 has been analyzed. For deposition at pressures ranging from 10-3 to 3 Torr, with no carrier gas, the process is dominated by fast gas-phase reactions. In situ analytical techniques, such as mass spectrometry and high-resolution electron energy loss spectroscopy, indicate that hydroxyl groups are reaction products and are imbedded into the growing oxide at temperatures from 300 to 600°C. Presence of these groups is detrimental to the electrical properties of metal-oxide-semiconductor (MOS) structures, e.g., by causing low-field breakdown and by increasing the interface state density. Low-pressure (SiH 4/O2) oxides are thus principally not well suited for gate-oxide applications because of their underlying chemistry.