On the mechanical properties of ultrathin titanium nitride films under different gas ratios of PVD process

Titanium Nitride (TiNx) thin film has numerous applications in semiconductors, nanotechnology, and various aspects of daily life. This study presents an approach to adjusting the mechanical properties of TiNx ultrathin films, including Young's modulus, residual stress, and coefficients of thermal expansion (CTE), by varying the gas ratio of N2 and Ar during the Physical Vapor Deposition (PVD) process (DC magnetron sputtering). In the experiment, TiNx films with three different gas ratios RN (= N2/(N2 + Ar)) were investigated. To demonstrate the feasibility of this approach, TiNx films with different RN values (0.3, 0.5, and 0.8) were deposited on SiO2 beams to form composite test cantilevers. Measurements reveal significant changes (ranging from 33 % to 2-fold) in Young's modulus, residual stress, and CTE of the TiNx films by varying the gas ratio during the PVD process. As a result, this study provides a straightforward approach and guidelines for users to tailor TiNx films according to specific application requirements. [Display omitted] •The MEMS cantilever test keys are employed to characterize the mechanical properties of PVD TiNx thin film.•Adjusting gas ratios (RN) affects the mechanical properties of TiNx film.•Young's modulus can be increased nearly 2-fold when the RN is changed from 0.8 to 0.5.•Residual stress can be reduced by 47 % when the RN is increased from 0.3 to 0.8.•Coefficient of thermal expansion can be increased by 33 % when the RN is decreased from 0.8 to 0.3.