Effects of crystal orientation, substrate type, and substrate temperature on residual stress of AlN thin films deposited by different deposition methods

Aluminum nitride thin film can be applied as a high-temperature material because of its excellent heat resistance and thermal conductivity, and high mechanical strength. In addition, application and application to surface acoustic wave devices using piezoelectric properties are expected, and it is known as a material that can replace ZnO. To obtain excellent crystal orientation, the residual stress behavior inside the thin film should be fully evaluated and identified. In this study, AlN thin films were deposited by the conventional PM sputtering method and the Two-Facing-Target (TFT) PM sputtering method using BLC glass and quartz glass with different thermal expansion coefficients as substrates. In the process of cooling the fabricated thin film, the effect of the difference in the coefficient of thermal expansion with the substrate on the residual stress of the thin film and the effect of the substrate temperature on the properties of the thin-film structure and the residual stress when the thin film was deposited were investigated. The AlN thin film deposited on the glass substrate by the conventional PM sputtering method showed a crystal structure in which the c-axis was preferentially oriented in the normal direction of the substrate surface, the same as the AlN thin film produced by the two-facing-target PM sputtering method. The AlN thin film deposited on the glass substrate had a crystal structure in which the c-axis was preferentially oriented in the normal direction to the substrate, and the c-axis orientation showed excellent c-axis orientation when the substrate temperature was higher than 523 K. In the case of the quartz glass substrate, the increase of the tensile residual stress was evident as the substrate temperature increased, and the effect of the thermal residual stress was confirmed.