Abstract
Polycrystalline Al-C-O-N films were prepared by microwave plasma chemical vapor deposition using an AlBr3-H2-N2-N2O-CH4-Ar gas mixture on an Si (100) substrate. The composition, structure and crystallinity of films as a function of N2O gas flow rate (0 to 10 sccm) and CH4 gas flow rate (0 to 60 sccm) were examined at a total gas pressure of 0.4 Torr, and a substrate temperature of 530°C. The Al-C-O-N films contained 0 to 53mol% oxygen and 0 to 6mol% carbon. Crystallinity of the films as a function of N2O and CH4 gas flow rates were classified following three regions: (1) highly c-axis oriented AlN, (2) the lower oriented AlN, (3) amorphous. The unit cell volume of AlN films in (1) and (2) increases with increasing carbon concentration in the films. Results of XRD, TEM and IR indicate that carbon and oxygen atoms take the place of nitrogen in the AlN lattice. Vickers microhardness of the polycrystalline Al-C-O-N film containing 4.3mol% of carbon and 3mol% of oxygen was about 26GPa, and higher than that of AlN (14GPa).
