Investigation of hydrogen impurities in PE-ALD AlN thin films by IBA methods

Abstract

Hydrogen impregnation is one of the main sources of contamination in AlN thin films obtained by atomic layer deposition method (ALD) as many studies report. Such impurities can be potentially detrimental to mechanical and electrical properties of the material. In this study methods belonging to ion-beam analysis (IBA) group, namely: elastic recoil detection analysis (ERDA), nuclear reaction analysis (NRA) and secondary-ion mass spectrometry (SIMS) were utilized to examine AlN thin films obtained by plasma-enhanced atomic layer deposition (PE-ALD) with use of trimethylaluminium (TMA) and N2+H2 gas mixture as precursors. Several depositions of AlN layers were carried out with different values of N2+H2 flux intensity (20, 100, 150 sccm) and TMA pulse (0.06, 0.12, 0.15 s) in order to investigate whether such alterations would produce any effect on the resulting films. Data obtained within the scope of this study suggest that AlN grown by PE-ALD exhibit rather low amounts of hydrogen impurities, especially when compared to thermal ALD. Furthermore, the effect of high-temperature treatment in N2 atmosphere was studied and was found out to produce a positive effect on the chemical composition of AlN films.