Investigation of Highly c-axis Oriented AlN Thin Film Re-growth

ABSTRACTThe properties of AlN films grown on a first set of differently treated AlN films have been studied by XRD, XPS, AFM, in-plane stress and interferometry. All films were deposited by dc pulsed sputtering at 300°C. The first set of films consisted of smooth, pure c-axis oriented AlN monolayers with narrow rocking curve width and excellent piezoelectric coefficient grown on platinized substrate in a large thickness range of 35–2000 nm. Subsequently, a 1000 nm AlN layer has been added. The use of a strongly alkaline developer during intermediate lithography steps and the time elapsed between the two steps of AlN re-growth were found to degrade the overall quality of the films. It's been shown that the alkaline developer etches down, increases the roughness and contaminates the surface of the AlN monolayer with mainly oxides and hydroxides while the exposure of the films to air develops a native oxide layer. By reducing the air exposure time and by the use of RF plasma cleaning prior to the re-growth process, a good piezoelectric coefficient can be recovered.

Plasma-Surface Interaction Limits for Remote H-Plasma Cleaning of Si(100)

ABSTRACTAn investigation of the parameters in H-plasma cleaning influencing H-diffusion and surface etching is described. The Si surface and subsurface regions were characterized with Raman spectroscopy and high resolution transmission electron microscopy (HRTEM), and the plasma parameters were monitored with a double Langmuir probe and optical emission spectroscopy. The parameters varied in the rf plasma cleaning were the substrate temperature, the rf power, and the plasma exposure time. It was found that low pressure and low power H-plasma exposure was effective in terms of cleaning the surface. In the 300°C, 20 Watts, 2 min. H-plasma exposure case, the Raman spectra indicated that there was no detectable H incorporation into the Si bulk and HRTEM showed no obvious defect microstructure in the near surface region and that the surface was smooth. In contrast, in the 150°C, 50 Watts, 60 min. H-plasma exposure case, HRTEM indicated that H-induced platelet defects formed in the Si(100) subsurface region and that the surface morphology was rough. Raman scattering revealed Si-H features at ∼2100 cm−1.