The performance of W40Re40B20 metallic amorphous thin film alloys as diffusion barriers between monocrystalline silicon substrates (<Si>) and aluminum or copper overlayers is reported. The films are deposited using d.c. and r.f. magnetron co-sputtering. Their crystallization temperature and resistivity are about 900°C and 200 μohmscm, respectively. The <Si>/W40Re40B20/Al and <Si>/W40Re40B20/Cu metallizations were vacuum-annealed at different temperatures for 30 min and characterized by 4He backscattering spectrometry, X-ray diffraction, scanning electron microscopy in combination with energy-dispersive analysis of X-rays, and electrical measurements on shallow junction diodes. The <Si>/W40Re40B20/Al structure was stable up to 500 °C and failed at 550 °C due to chemical reactions between the barrier and aluminum. A formation of cracks in the bilayer <Si>/W40Re40B20/Cu structure is responsible for its failure at 600 °C. The results demonstrate that it is fruitless to raise the crystallization temperature of an amorphous metallic film if its ability to react with the adjacent materials is not suppressed as well.
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