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 induced CoSi2 formation as well as the interaction between Co and thick isolation oxides during ion-beam mixing and rapid thermal annealing were investigated. It was shown that a native oxide layer between the Co and the Si has a strong influence on reaction temperature and properties 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 reaction temperature and in formation of homogeneous layers. Further investigations revealed that silicide grain formation is possible on thin thermal oxides up to 10 nm. Using oxide layers thicker than 100 nm, no CoSi2 formation could be detected after thermal treatment but a rather severe damage of the SiO2 surface resulted. In contrast to this, ion-beam mixing with Ge or As ion doses at or above 5 x 10(14) cm(-2) and subsequent annealing led to good adhesion of Co on SiO2 without damage of the oxide surface.