Platinum silicide formation has been studied by Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) in conjunction with argon ion depth profiling. These techniques were used to probe the chemistry of the interface between the Pt metal and PtSi formed from two standard platinum deposition processes: dc sputtering and filament evaporation. The results indicate that after sintering in nitrogen, the PtSi is separated from the platinum metal by a ``protective'' layer which has tentatively been identified as PtSiO4. This ``protective'' layer has a significantly slower etch rate in standard etchants than the platinum metal and platinum silicide and may be formed during sintering by an interaction between the platinum metal and the native silicon dioxide. The platinum silicate identification is based on the XPS ``chemical shifts'' found for both the platinum and silicon core levels. The silicate layer formation appears to be independent of the technique for platinum deposition.