Thin film Ni-Si solid-state reactions: Phase formation sequence on amorphized Si

The phase formation sequence during the thermally induced solid-state reaction of a 10-nm-thick magnetron-sputtered Ni film with a Si(001) substrate amorphized by ion implantation (a-Si) is investigated using a combination of in situ temperature-resolved x-ray diffraction and ex situ x-ray pole figure analyses, transmission electron microscopy, and Rutherford backscattering spectrometry. Our results reveal (1) that the metastable theta-phase grows from delta-Ni2Si and directly transforms into NiSi and (2) that cleaving the as-prepared, amorphized samples are often subject to a spontaneous reaction possibly resulting from cleaving. In the spontaneously reacted samples, a mixture of theta and NiSi is observed from the beginning of the thermal treatment. The theta phase exhibits a (110) fiber texture with a +/- 10 degrees misorientation, which is then inherited by NiSi. The rest of the phase sequence is the same as for nonreacted samples, the NiSi2 growing from 390 degrees C if the amorphized Si is not completely consumed. (C) 2013 American Vacuum Society.