OBSERVATION OF INTERMETALLIC PHASES FORME D IN AL AU AND AL/CU THIN-FILM COUPLES USING OPTICAL REFLECTIVITY TECHNIQUE/

Formation of intermetallic phases in Al/Au and Al/Cu thin film couples annealed at temperatures between 100-degrees-C and 250-degrees-C has been investigated using X-ray diffraction and optical reflectivity tec hniques. Several intermetallic compounds which exist in a binary equil ibrium phase diagram were produced in the couples after annealing. The formation and growth of Al2Cu, AlCu and Al2Au phases could be observe d by the variation of optical reflectivity with wavelength. The interd iffusion of metals in Al/Au thin film occurred faster than that in Al/ Cu during annealing. For example, the growth rate constants (k) of Al2 Au and Al2Cu layers in the thin film couples annealed at 200-degrees-C were 3.4 x 10(-8) and 2.4 x 10(-9) m/s1/2, respectively. The growth r ate of these intermetallic layers was faster in thin films than in dif fusion couples of bulk metals.