DETERMINATION OF THE ATOMIC MIXING LAYER IN SPUTTER PROFILING OF TA/SI MULTILAYERS BY TEM AND AES

Sputter‐deposited multilayers of Si and Ta with a nominal period length of a double layer (Ta + Si) of 20 nm were studied with AES depth profiling and with transmission electron microscopy (TEM). The asymmetric shape of the measured Si layer profiles was fitted to model calculations based on preferential sputtering of Si and an atomic mixing zone length of 4 nm for 3 keV Ar+ ions at a 36° incidence angle. TEM images of cross‐sections of the original sample show sharp Si/Ta and Ta/Si interfaces, with a width of ∼ 0.5 nm. The atomic mixing zone length of the sputter‐profiled sample was observed directly by TEM and was determined to be 4.0 nm, in accordance with the AES profile evaluation. It is concluded that the observed asymmetric broadening of the shape of the measured AES sputtering profiles is due mainly to atomic mixing and is enhanced by preferential sputtering of Si. Copyright © 1990 John Wiley & Sons Ltd.