The effect of a Mo interlayer on the electrical properties and thermal stability of nickel silicides was investigated. It is shown that the samples with the interlayer produced lower sheet resistances than did the samples without the interlayer, for annealing temperatures in the range 400-800degreesC. Glancing angle X-ray diffraction results show that NiSi is transformed into NiSi2 at temperatures in excess of 700degreesC, at which a tetragonal MoSi2 phase is also formed. It is also shown that the Mo layer moves toward the surface region, when annealed at temperatures in excess of 500degreesC. Transmission electron microscopy and scanning electron microscopy results show that the insertion of the interlayer was effective in improving the surface morphology of the silicide films and the uniformity of the silicide/Si interface. (C) 2003 The Electrochemical Society.