## 1 Introduction  
Titanium nitride (TiN) is used in a wide range of applications such as in diffusion barriers in microelectronics, protective coatings on biomedical devices, hard and decorative coatings on machine tools, or in the manufacturing of micropag discharge devices owing to its excellent physical, chemical, electrical, and mechanical properties [1; 2; 3; 4; 5; 6; 7; 8; 9; 10; 11]. The physical properties of TiN include high hardness, excellent adhesion properties, wear and corrosion resistance, high melting temperature, thermal and chemical stability, and biocompatibility [12; 13]. In the semiconductor industry, TiN is used as a gate electrode and a diffusion barrier layer in complementary metal-oxide semiconductor (CMOS) technology owing to its high electrical conductivity and diffusion barrier properties [14; 15]. TiN exhibits very good thermal conductivity and high stability, especially under high-temperature environments, because of its high melting point (2950 \({}^{\circ}\)C).  
In the TiN thin film deposition process, the adhesion and residual stress characteristics vary depending on the substrate material [16], deposition temperature [16; 17], presence of some buffer layer between the substrate [14] and TiN film, and bias voltage of the substrate [16; 18]. The production of a TiN thin film by sputtering TiN at a sufficiently high temperature leads to a composition that is similar to that of the stoichiometric bulk material; the substrate temperature during the deposition process has a significant effect on some properties of the TiN thin film. Thus, an appropriate substrate temperature can improve the adhesion strength of TiN thin films [5; 6; 7].  
The residual stress and adhesion characteristics of a thin film are critical factors for determining the durability and lifespan of nanostructures. Grazing-incidence X-ray diffraction (GIXD) techniques that use the XRD characteristics [7; 8; 14; 15], etch-back [10], and nanoindenter testing [17] are employed for measuring the residual stress. Further, a nanocatch test that measures the critical load value at the breakage of a thin film using a nanoindenter [18], the scotch tape test that uses scotch tape [19], and a pull-off test [20] that uses an epoxy coating are employed to measure the adhesion characteristics. These above-mentioned test methods are both destructive and non-destructive characterization techniques; however, they have a limitation in that they require the fracture for measurement.  
The application of ultrasound is a promising method for non-destructive residual stress measurement. This method employs the acoustoelastic effect, which is the relationship between the velocity of the ultrasonic wave and the internal/applied stress; further, the method facilitates the understanding about material properties for physical property evaluation, acoustic anisotropy, twin deformation, damaged layer, thin-film thickness measurement, and surface layer residual stress measurement by measuring the speed of sound with high precision in a micro-area. A leaky surface acoustic wave (LSAW) is generated by the V(z) technique; this wave propagates along the surface when the half aperture angle of the acoustic lens of the ultrasonic microscope is greater than the critical angle for generating a surface wave. The LSAW can be used to measure the residual stress and adhesion properties [21; 22; 23].  
In this study, the characteristics of the deposited TiN thin film are analyzed using the V(z) technique, which measures the velocity of the LSAW propagating along the surface of the material using an ultrasonic microscope as a substrate temperature variable of DC magnetron sputtering. In addition, the correlation between the residual stress measurements performed using a four-fold circled XRD and the adhesion characteristic analysis that uses the scratch test of nanoindentation and the V(z) technique of ultrasonic microscopy is analyzed.