Structure and fracture toughness of TiAlN thin films deposited by deep oscillation magnetron sputtering

•TiAlN thin films were deposited by deep oscillation magnetron sputtering.•Low deposition temperature was adjusted in oscillation voltage on-time and off-time.•Microstructure of TiAlN thin films changed from Zone I to Zone T with peak power.•Fracture toughness of TiAlN thin films in Zone T was optimized at a peak power.•Bombarding energy Ebi and mobility D of species were discussed in deposition process.