Plasma power effect on crystallinity and density of AlN films deposited by plasma enhanced atomic layer deposition

Aluminum nitride (AlN) film is a promising material which is used in various fields. In this study, AlN films with different plasma powers were grown by remote plasma atomic layer deposition. Saturation experiments have been applied in the plasma power between 1000 and 3000 W. The influence of plasma power on preferential orientation, chemical, optical, and electrical properties of AlN films are investigated. AlN films displayed multiphase hexagonal wurtzite crystal structure with (002) preferential orientation for higher plasma power, while the predominant orientation shifted toward (100) at lower plasma power. The optical emission spectroscopy analyses show that NH and NH2 radicals conduce to the deposition of AlN films and H radicals selectively dissociate Al–OH bonds which were on AlN film surface and etch deposition films. Atomic force microscopy measurements show that the 1500 W prepared AlN film with smallest surface roughness may be related to the relatively smaller concomitant crystal grains of (100) and (002). X-ray photoelectron spectroscopy investigation presents that oxygen content decreases as the plasma power increases. The obtained maximum value of dielectric constant and breakdown electrical field of AlN film deposited at 3000 W is 8.23 and 5.42 MV/cm, respectively.