High-Energy Neutral Atoms in the Sputtering of ZnO

Abstract

Dips were observed in the distribution curves of the deposition rates of ZnO films prepared both by planar diode and by planar magnetron sputtering. These dips are ascribed to high-energy neutral atoms bombarding the films. The influence of high-energy neutral atoms on the mixed orientation of ZnO film is also investigated in planar diode sputtering. In planar magnetron sputtering, which gives highly [00·2] oriented ZnO films, the correlation between the degree of c-axis orientation and the flux of high-energy neutral atoms is examined. It is found that high-energy neutral atoms should be considered when trying to obtain highly-oriented ZnO films.

On performance limitations and property correlations of Al-doped ZnO deposited by radio-frequency sputtering

“…4), we conclude that our AZO film is partially resputtered by energetic particle bombardment in the low-pressure regime. Previous studies have shown that not only can resputtering effects exist in AZO, but they can also be spatially distributed: the regions of the film where a higher flux density of energetic ions is expected may have a higher resputtering rate [28,29]. By inspection of the radial distribution of deposition rate in our films (Fig.…”

“…However, it can be assumed that increasing deposition pressure leads to a reduction in the flux density gradient due to a larger contribution from species with an off-normal incidence angle caused by more frequent collisions. This effect can be seen to some extent in angle-resolved flux density measurements [28].…”

“…The summed flux density from of the two species was only slightly decreasing with increasing pressure up to about 8 mTorr, then a faster exponential decay occurred, characterized by a 50% decrease every 10 mTorr. The spatial distribution of the O − ion flux density was investigated in several works, which generally found a larger flux density near x e , corresponding to the largest plasma density or, equivalently, to the strongest magnetic field at the target [9,28,41]. It is difficult to extract quantitative trends, because the flux density distribution depends on the age of the target [9,42], the strength of the magnetic field in the magnetron [10], the type of excitation [9] (RF or DC), and energy-dispersive measurements are typically affected by the limited acceptance angle of the probe [9,15].…”

Texture development of non-epitaxial polycrystalline ZnO films

“…c-axis-oriented ZnO films were obtained at P around 1 mTorr [5,9]. Tominaga et al [7] observed that increasing pressure around 0.1 Torr degraded the c-axis PO. It seems that increasing P leads PO from the a-axis to c-axis and finally to random orientation.…”

Effect of incident angle of target molecules on electrical property of Al-doped ZnO thin films prepared by RF magnetron sputtering

“…The growing film at each location would be exposed to different environment such as the amount of plasma damage, the amount of materials supplied, and incident angle of the sputtered materials. There are many reports that the amount of plasma damage will be different according to the relative distance of substrate against the target center, hence the film resistivity in turn [4][5][6][7]. Firstly, plasma damage can increase defect density of film and provide carrier trap sites so as to increase the film resistivity.…”