A new approach to the development of very thin Pd2Sihyphen;tohyphen;Si contacts for possible future use in ultrasmall devices is described. It is based on the principle of diluting the silicidehyphen;forming metal (Pd in this case) with Si, by codeposition of these two elements onto a singlehyphen;crystal Si substrate. The composition of the codeposited layer has been chosen as Pd80Si20, which is a metastable alloy with an amorphous structure. During annealing of the layered structure, Pd is extracted from the amorphous alloy to form the metalhyphen;rich and very stable compound Pd2Si at the interface. At the same time, the decomposing Pd80Si20is also converted in Pd2Si. In this way a silicide is formed for which only sim;50percnt; of the required Si need be supplied by the Sihyphen;substrate, resulting in a very shallow silicide contact. In the illustrated case, with 400 Aring; of Pd80Si20on Silang;100rang;, only sim;80ndash;100 Aring; of substrate Si is consumed. The microstructural properties of the formed silicide have been studied byinsitutransmission electron microscope experiments, while the electrical characteristics of Pd2Sihyphen;tohyphen;Si Schottky diodes, fabricated by this technique, have been studied by Schottky barrier height (SBH) measurements from the currenthyphen;voltage curves. By choosing the annealing treatments of these two sets of identical specimens, the microstructural and electrical properties could be correlated. It is shown that overannealing of a Pd2Sihyphen;tohyphen;Si contact formed in this way should be avoided, since this gives rise to a lowering of the SBH. Finally, it is demonstrated that initially bad Schottky diodes (ideality factorngsim;1) can be restored to a goodnquest;1 condition by annealing.
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