VARIATION OF INTERNAL-STRESSES IN SPUTTERED TA FILMS

It has been found that the stress of a sputtered Ta film gradually changes toward compression in a normal atmosphere. It was found that the cause of this Ta film stress change is quick oxygen diffusion along grain boundaries. The amount of this stress change was measured to be about approximately 3 X 10(7) N/m2 when the Ta film was sputtered with Ar gas below 3.5 Pa. The stress change occurred neither in a vacuum nor in a nitrogen atmosphere, but only in an oxygen atmosphere. Once the Ta films had been annealed for 60 min at 100-degrees-C in an oxygen atmosphere, no further stress change was observed.