LOW-PRESSURE THERMAL CVD SYNTHESIS OF TUN GSTEN NITRIDE THIN-FILM USING WCL6 AS TUNGSTEN SOURCE

The dependence of growth parameters (deposition temperature and gas co mposition) on the deposition rate of tungsten nitrides on a qualtz sub strate was studied by chemical vapor deposition (CVD) at temperatures of 500 to 803 degrees C under total pressure of 0.12-0.17 kPa, total f low rate of 60 ml/min in a gas mixture of WCl6-NH3-H-2 (in Ar). The me chanism of the deposition of tungsten nitride film with time on stream was also discussed. The tungsten nitride films were analyzed by scann ing electron microscopy, X-Ray diffraction, and X-Ray photoelectron sp ectroscopy. W2N (200) plane was preferably deposited for thickness of 0.5 mu m, but W2N (111) plane was mainly orientated above thickness of 1 mu m. The thin film was smoothly deposited about 500 degrees C and has a fine structure without defects such as cracks and tearings. The reaction orders for W2N deposition were 0.4, 0.3, and 0.3 with respect to WCl6, NH3, and H-2, respectively.