INTERFACE STRUCTURE AND ADHESION OF SPUTTERED TI LAYERS ON SI - THE EFFECT OF HEAT-TREATMENT

Interface structure and adhesion of the Ti films on Si substrates pret reated by an Ar ion bombardment have been investigated by high resolut ion transmission electron microscopy, energy-dispersive X-ray spectros copy, electron diffraction and Auger electron spectroscopy (AES). Two extra layers were observed between the Ti layer and Si substrate in th e as-deposited condition. One was an amorphous Si (a-Si) layer about 2 nm thick which contain Ar atoms on the single-crystal Si surface, and the other is an amorphous Ti-Si (a-Ti-Si) mixed layer about 3 nm thic k on the a-Si layer. A peeling test indicates that complete detachment occurred at the interface between the a-Si and the a-Ti-Si mixed laye r. However, the adhesion was increased by the heat treatment at 723 K for 30 min, and peeling ratio was reduced to about 10%. Ar atoms distr ibuted at the interface seem to cause the reduction of the adhesion. T he heat treatment changed the distribution of Ar atoms at the interfac e. The profile of the interface was also changed to increase the area of direct contact between the Ti-Si mixed layer and the Si substrate. Both effects seem to enhance the adhesion.