OXYGEN SPECIATION IN ALUMINUM NITRIDE SUB STRATES BY X-RAY-DIFFRACTION AND HIGH-TEMPERATURE GAS EXTRACTION WITH THERMAL RAMPING

AlN is one of the best materials for microelectronic circuit packaging . The sintering of AlN, a covalently bonded material, is greatly aided by the addition of densification aids, among which yttrium oxide is t he most common. This results in a rich microstructure, with yttrium al uminate and aluminum oxinitride second phases. A clear correlation of the microstructure with thermal conductivity has not been carried out yet, though oxygen dissolved in AlN lattice (between 0.2 and 0.7%) is likely to be the most important factor. The thermal conductivity decre ases when the oxygen content in the AlN lattice increases. Thus, the d etermination of the total oxygen content of the ceramic is too short. Oxygen dissolved in the lattice must be separated of the oxygen bound in surface oxide layers and in the grain boundary phases. This is achi eved through X-Ray diffraction analysis and Hot Gas Extraction (HGE) m ethod applied in a differential manner. A good correlation between the se two methods is evidenced by a comparative analysis of commercial su bstrates.