Low-temperature (< 100°C) growth of AIN by ion beam assisted deposition

During the past few years, there has been growing interest in aluminum nitride (AIN) thin films because of their excellent optical, electrical, chemical, mechanical and high-temperature properties. Ion beam assisted deposition (IBAD) was used to deposit AIN films on flat and curved substrates, including Si, SIMOX, sapphire, quartz, aluminum, stainless steel, and carbon, at temperatures substantially below 100°C. The objective was to enhance the physical and mechanical properties of AIN film by controlling the crystal size and structures. Experimental results, as obtained by Rutherford backscattering spectroscopy (RBS) show the formation of stoichiometric AIN. Plan-view/cross-sectional transmission electron microscopy (TEM), clearly demonstrated the formation of a smooth, uniform AIN film. Electron diffraction and dark field TEM studies clearly show the growth of AIN crystallites with cubic and/or hexagonal structures and dimensions of 30 to 100angstrom. The films are transparent and have good adhesion to all substrates. In addition to excellent high temperature (up to 1050°C measured) and chemical stability (shown through a variety of acid tests), these films have demonstrated extreme hardness, greater than two times that of bulk AIN.