The Influence of Argon Cluster Ion Bombardment on the Characteristics of AlN Films on Glass-Ceramics and Si Substrates.

Ivan V Nikolaev,Pavel V Geydt,Ivan A Azarov,Vladimir I Strunin,Aleksandr V Kapishnikov,Evgeny Y Gerasimov,Vladimir A Volodin,Nikolay G Korobeishchikov

doi:10.3390/nano12040670

Abstract

In this paper, the influence of surface modification on the characteristics and properties of AlN thin films on Si and glass-ceramics substrates is investigated. The surface modification was made at various parameters of argon cluster ions. By using XRD and Raman spectroscopy, it was shown that the obtained AlN films have a hexagonal structure with a characteristic direction of texturing along the c axis and slight deviations from it. A comparison of the AlN surface morphology obtained by atomic force microscopy before and after cluster processing was demonstrated. This demonstrated that the cluster ions with low energy per atom (E/N = 10 eV/atom) have a high efficiency of surface smoothing. A decrease in the intensity of the Raman peaks and an increase in their full-width after bombardment with cluster ions were found, which may be caused by a change in the physicochemical state of the surface. The optical properties, the quality of the boundaries, and the distribution map of the thickness of the functional layer of AlN were investigated by the methods of spectral and spatial resolution ellipsometry. By using the cross-sectional SEM, the direction of crystallite texturing was demonstrated. The influence of argon cluster ion bombardment on the stoichiometry of samples was analyzed by EDX spectroscopy. The results obtained demonstrate the efficiency of the cluster ion smoothing of polycrystalline thin films for microelectronics, particularly when creating surface acoustic wave resonators.

Highlights

IntroductionDue to its piezoelectric and pyroelectric parameters, such as the piezoelectric coefficients (e15 = −0.33 ~ −0.48 C/m2 , e31 = −0.38 ~ −0.82 C/m2 , e33 = 1.26–2.1 C/m2 and d33 = 4–6 pC/N) and the relative permittivity coefficient (ε11 = ε22 = 9, ε33 = 11), aluminum nitride is used in optomechanical and electroacoustic devices, phonon crystals, and nonlinear optics [8,9,10,11,12,13,14,15]
The diffraction pattern for AlN films indicates the presence in the samples of the preferred orientation of crystallites in the direction of the c axis, with the March-Dollars parameter in the range of 0.35–0.43, which is in good agreement with the literature data [25,28,51]
The structure and optical characteristics of AlN films on glass-ceramics and Si substrates before and after argon cluster ion bombardment were investigated for the first time

Summary

Introduction

Due to its piezoelectric and pyroelectric parameters, such as the piezoelectric coefficients (e15 = −0.33 ~ −0.48 C/m2 , e31 = −0.38 ~ −0.82 C/m2 , e33 = 1.26–2.1 C/m2 and d33 = 4–6 pC/N) and the relative permittivity coefficient (ε11 = ε22 = 9, ε33 = 11), aluminum nitride is used in optomechanical and electroacoustic devices, phonon crystals, and nonlinear optics [8,9,10,11,12,13,14,15] As a rule, such devices are in the form of thin-film composite layers containing an AlN layer. The main advantages of magnetron sputtering are the fast speed of layer growth and the low price of production, which make it a relatively affordable technological method and have led to the widespread use of this technique, including the manufacturing scale [22,23,24]

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