INFLUENCE OF OXIDE THICKNESS ON ION-BEAM-INDUCED AND THERMAL COSI2 FORMATION

In this study, the influence of thin oxides on thermal and ion-beam in duced CoSi2 formation as well as the interaction between Co and thick isolation oxides during ion-beam mixing and rapid thermal annealing we re investigated. It was shown that a native oxide layer between the Co and the Si has a strong influence on reaction temperature and propert ies of the formed silicide layer whereas ion-beam mixing with Ge doses at or above 5 x 10(14) cm(-2) resulted reproducibly in a decreased re action temperature and in formation of homogeneous layers. Further inv estigations revealed that silicide grain formation is possible on thin thermal oxides up to 10 nm. Using oxide layers thicker than 100 nm, n o CoSi2 formation could be detected after thermal treatment but a rath er severe damage of the SiO2 surface resulted. In contrast to this, io n-beam mixing with Ge or As ion doses at or above 5 x 10(14) cm(-2) an d subsequent annealing led to good adhesion of Co on SiO2 without dama ge of the oxide surface.