Capacity coupled r.f. Discharge plasma jet treatment of a-SiC:H structures

Amorphous hydrogenated silicon carbide (a-SiC:H) thin films were treated in a capacity coupled r.f. discharge plasma jet working in nitrogen. The samples, with a carbon content in the range of 30%-50%, were deposited onto Si(100) wafers by plasma enhanced chemical vapor deposition. The capacity coupled r.f. discharge (less than 100 W) is generated in flowing nitrogen or ammonia in a small distance (1-2 mm) gap, at medium pressure (3-25 torr). The gap is limited by a planar (40 mm diameter) electrode and a nozzle (1-2 mm) opening. Plasma expands as a bright nitrogen plasma jet in a larger vacuumed vessel. The sample's holder ( which can be heated) was placed downstream the nozzle at several centimeters distance, being exposed to the plasma beam. In this way the samples (a-SiC:H) were irradiated. Various techniques, such as X-ray diffraction, X-ray photoelectron spectroscopy, Fourier infrared transmission spectroscopy measurements, spectroscopic ellipsometry and microhardness measurements were used to characterize the induced composition evolution towards Si-C-N (SiC-SiN-CN) mixtures.