Improvement of Er-silicide formation on Si(100) by W capping

Pinhole or pyramidal defect is often observed in Er-silicide (ErSi2 − x) formed on Si by solid-state reaction. To solve the problem, Er and W capping layers are successively deposited onto Si wafer. Er reacts with Si to form ErSi2 − x during rapid thermal annealing. Then the W capping layer and the un-reacted Er layer are selectively etched. The formed ErSi2 − x film is observed quite smooth without any pinhole or pyramidal defect. This technique will also improve the contact properties of the ErSi2 − x on p-type Si. With the W capping layer, the Schottky barrier height of ErSi2 − x on p-type Si is measured to increase from 0.54–0.66 eV to as high as 0.71 eV, corresponding to 0.41 eV Schottky barrier height on n-type Si. The Er silicide process with a W capping layer is promising for applications in devices such as Schottky barrier source/drain metal-oxide-semiconductor field-effect transistors.