The effects of nitrogen partial pressure on the microstructure of amorphous carbon nitride films

ABSTRACT

The amorphous carbon nitride (a-CN_x) films with varying nitrogen content were deposited on Si (100) wafers substrates using radio frequency magnetron sputtering (RFMS) from graphite target at different nitrogen partial pressure. The influence of nitrogen partial pressure on the microstructure and phase composition of a-CN_x films were researched systematically. The films were characterized by atom force spectroscopy (AFM), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). AFM results showed cluster structure in a range of tens to hundreds namometers existed on the surface of the films and the surface roughness increased with the increase of nitrogen partial pressure. Ratio of I_D/I_G increased with the nitrogen partial pressure, while the sp³ phase content from fitting results of XPS displayed reverse trend. The nanohardness of a-CN_x films characterized by nanoindentation test decreased with the increase of nitrogen partial pressure, which consisted with the results of Raman and XPS. Thus high nitrogen partial pressure caused the mechanical properties of a-CN_x films decrease.

KEYWORDS:

• Amorphous carbon nitride films
• RFMS
• nitrogen partial pressure
• microstructure
• mechanical properties

Funding

This study was financially supported by National Natural Science Foundation of China (Grant Nos. 51005117 and 51575269) and Graduate Student Innovation Base (Laboratory) Open Foundation of Nanjing University of Aeronautics and Astronautics (kfjj20160503).