SYNTHESIS OF TITANIUM BASED NITRIDE THIN FILMS BY PLASMA FOCUS SYSTEM

Abstract

The present research is motivated by the remarkable mechanical, thermal and electronic properties of titanium based nitride thin films that have many applications ranging from coatings on cutting tools to diffusion barrier microelectronic applications. This work reports the first successful attempt to grow titanium based nitride thin films, specifically TiAlN, nc- TiN/ a-Si 3 N 4 , nc- (Ti, Al) N/ a-Si 3 N 4 and Ti-Si-N using plasma focus device. The synthesize of these films using different deposition techniques have been reported earlier but the use of plasma focus technique is one of the prospective hybrid deposition method which is not only economical, simple, efficient but also provide high deposition rate and good adhesion SS in less time compared to other available thin film synthesize techniques. The results of these experiments show the successful growth of titanium based nitride thin films using plasma focus device of energy 2.3 kJ. The following four types of different experiments were performed: In the first experiment, the sputtered titanium ions and energetic nitrogen ions emitted from Mather-Type plasma focus device were used to synthesize nanocrystalline TiN/amorphous-Si 3 N 4 thin films. The crystallite size analysis showed strong dependence on the number of focus shots. The crystallinity of TiN thin films wasfound to increase with increasing the number of focus shots. SEM results showed net like structure ofthe film deposited for 15 numbers of shots, which are in the form of elongated grains of Si 3 N 4 embedded in TiN crystals. The average surface roughness calculated from AFM images indicated that the average surface roughness increased for films deposited with increased number of focus shots. In the second experiment, a plasma focus device was used to prepare thin films of nc-(Ti,Al)N/a-Si 3 N 4 at room temperature. The plasma focus device, fitted with copper anode encapsulated with Ti 0.5 Al 0.5 anode, operated with nitrogen as the filling gas was used. Films were deposited with various number of focus shots, at 90 mm from top of the anode and at zero angular position with respect to anode axis. XRD patterns showed the growth of polycrystalline (Ti, Al) N thin films with orientations in the (111), (200), (220) and (311) crystallographic planes. Behavior of lattice constant, grain size and film roughness of xvideposited film as a function of variation in number of focus shots was discussed. SEM micrographs of film deposited with 15 number of focus shots exhibited well-developed net like structure of nc-(Ti,Al)N/a-Si 3 N 4 and possibly nc-(Ti,Al)N/a-Si 3 N 4 /a-AlN or nc-TiN/a- Si 3 N 4 /a-AlN. Surface Roughness ranging 64 nm to 89 nm was also observed. In the third experiment, TiAlN coatings were synthesized by a dense plasma focus deposition system. The effect of focus shots on the crystallography, microstructure, surface morphology, roughness and hardness was investigated. The X-ray diffraction (XRD) data showed TiAlN coatings crystallized in the cubic NaCl B1 structure with orientations in the (111), (200), (220) and (311) crystallographic planes.SEM micrographs showed dense and SS uniformly spread film with fine-grained morphology with hardly any void. Grain size and roughness were found to decrease, whereas thickness and hardness were found to increase, with increasing focus shots. In the fourth and the last experiment, a plasma focus device was used to prepare thin films of Ti-Si-N. XRD patterns showed the growth of polycrystalline TiN thin films. The results revealed that the grain size was correlated to the amount of silicon added. SEM results showed Ti–Si–N film exhibited a denser and amorphous compact structure almost without obvious defects due to addition of Si content in TiN structure. The surface roughness of synthesized thin films was much smoother compared to Plasma focus deposited thin films reported previously, the average surface roughness ranged from 0.23 nm to 9.39 nm.