The introduction of rapid thermal processing for silicide formation has triggered a lot of research to temperature uniformity and reproducibility in RTP systems. From the other side there has been the demand to make the process itself as robust as possible for temperature variations. Indeed the way the module is set up can open or close the thermal process window for silicidation. In addition to the temperature, the ambient control is to be taken into account. Although gasses are specified to a low level of contaminants, the RTP step needs to be optimized for optimal contaminant reduction. Besides, the process wafer itself can be a source of contamination. In this paper an overview will be given of the role of temperature and ambient during RTP on the silicidation processes. The effect of the wafer on ambient purity will be highlighted. It will be shown that the latter can also have an impact on other process steps in the interconnect technology.