Invited Paper TF+EM+NS+SS-ThA8
Aluminum Nitride Thin Films Deposition, Properties and Applications

Thursday, October 31, 2013, 4:20 pm, Room 104 A

Aluminum nitride (AlN) is a wide bandgap semiconductor and showing intrinsic properties such as high thermal conductivity, high electrical resistivity, good mechanical hardness and efficient piezoelectricity. Due to its intrinsic properties, single-crystalline AlN is a promising III–V semiconductor for applications in high power electronics and optoelectronics such as HEMTs, UV light-emitting diodes and acoustic waves devices. AlN films are grown on a variety of substrates using different deposition methods including chemical vapor deposition techniques and molecular beam epitaxy, laser ablation and reactive sputtering techniques. Among these methods, sputtering techniques permit to obtain c-axis oriented AlN films with small surface roughness at relatively low temperatures. Both modes of Magnetron Sputtering are presented: the DC mode and the HiPIMS mode (High Power Impulsed Magnetron Sputtering) for reactive AlN synthesis. HiPIMS for deposition of insulating AlN thin films were used and compare to the DC mode. The processes are optimized for working with Aluminum targets in a reactive atmosphere (Ar-N₂). As the plasma characterization of the ionized species is necessary in order to understand pulsed plasma process, time-resolved investigations were carried out using Optical Emission Spectroscopy and Mass Spectrometry was used for quantifying the ionic and neutral species reaching the substrate and the results are compared to the DC case. The AlN film stress was measured by the substrate curvature technique. The AlNfilm quality was characterized and by X-ray diffraction analysis (XRD), UV Raman spectrometry and Ellipsometry. The first purpose of this contribution consists to compare the structural and microstructural properties of AlN films deposited by DCMS and HiPIMS, in particular, in order to study the influence of the ionic bombardment resulting from the different discharges. Then, from the first deposition optimization study, we developed the epitaxial growth of AlN on a specific buffer layer on Silicon (111) and its electrical characterizations are presented. This AlN epitaxial layer obtained by magnetron sputtering was used to re-growth a thick GaN film in order to obtain HEMT device. This original structure exhibits a low drain current collapse which may be attributed to the enhanced thermal dissipation properties of the structure.

The present study has been supported by the French National Research Agency under grant ANR-2010-EMMA-030 CREATIVEPI.