BN protective coating for high temperature applications Ravi Bathe, R.D. Vispute, Daniel Habersat, Ichiro Takeuchi, R.P. Sharma, T. Venkatesan. T.S. Zheleva 1 and Ken Jones 1 CSR, Department of Physics, University of Maryland, College Park, MD 20742. 1 United States Army Research Laboratory, Adelphi, MD 20783. ABSTRACT We report on the fabrication, characterization, and processing of boron nitride films for use in high temperature applications such as field passivation, capping layers for thermal annealing of SiC, and protecting metallic filaments from their working environments. The BN films have been fabricated by pulsed laser deposition and spray techniques. The deposited films were characterized by X-ray Diffraction, Fourier Transform Infrared Spectroscopy, Ultraviolet- Visible Spectroscopy, Rutherford Backscattering Spectrometry and Transmission Electron Microscopy. The BN films deposited in the temperature range of 200-500°C have been found to be poorly crystalline, whereas the films fabricated above 600°C have been found to be microcrystalline. The as-deposited films were annealed at various temperatures ranging from 900°C to 1700°C in order to densify the films and study the applicability of the coatings. An AlN buffer layer was also applied in a few cases to improve chemical bonding with the substrate. Adhesion of the films with the heater components was greatly improved for high temperature annealed samples due to good interfacial bonding with the substrate material. Our results on the properties of BN films with an emphasis on characterization, processing, and implications for high temperature applications are discussed. INTRODUCTION Protective coatings of ceramic materials are of great interest for high temperature applications. In particular, these coatings are required for the protection of electronic components, high temperature filaments, and parts that are constantly exposed to various atmospheres at high temperatures [1]. For example, Silicon Carbide (SiC) is the most promising wide band gap semiconductor material for high temperature, high power, and high speed electronic devices, which need high temperature annealing treatment at up to 1800°C to remove the ion-implantation induced damage and to electrically activate the dopants [2,3]. The high temperature coatings or passivation layers are required on SiC to prevent surface roughening and changes in the surface composition due to the preferential evaporation of silicon at elevated temperatures during annealing. Another example is the metallic elements that are used in high temperature wafer heaters or furnaces, which are exposed to various atmospheres at high temperatures. The metallic elements can be coated with high temperature stable materials such as BN, Al 2 O 3 , or MgO. Boron nitride and aluminum nitride thin films and coatings are ideal material candidates in reducing the effects of atmosphere and high temperature due to their structural and chemical stability at temperatures >1400°C [4-6]. Though the properties of BN and AlN are compatible to high temperature applications, a fundamental understanding of the factors that govern the performance of the protective coatings is needed to provide a sound basis for the development of advanced products. In this paper we report on the fabrication, characterization, and processing of BN and BN/AlN dual layer films deposited on SiC, Si, and metallic elements. Mat. Res. Soc. Symp. Proc. Vol. 697 © 2002 Materials Research Society P3.3.1