Interdiffusion and reaction in (CrSi)/Al and (CrSiO)/Al thin film systems

Abstract

The interactions in the (CrSi)/Al and (CrSiO)/Al film systems as a result of thermal load were investigated with regard to the electrical properties and the metallurgical stability. The layers were deposited on Si/SiO 2 and NaCl substrates using a reactive d.c. magnetron sputtering technique in vacuum sequence. The film systems where characterized by means of secondary-ion mass spectrometry and transmission electron microscopy-transmission electron diffraction. The electrical resistance and its temperature coefficient and the reflection coefficient were measured. In both film systems the film components had already been intermixed during deposition. In the (CrSi)/Al system the amorphous CrSi layer begins to crystallize at a temperature of 260°C, thereby forming CrSi 2 and giving rise to strong interdiffusion at 400°C. The thermal stability in the (CrSiO)/Al system is improved by the oxygen incorporated. The formation of CrSi 2 is then retarded to 450–500 °C as is the beginning of intensive interdiffusion. Upon heat treatment the two film systems show local defects which are caused by different mechanisms. The changes in physical properties observed are attributed to the chemical and structural alterations in the film systems.