Method for forming metal silicide on a semiconductor surface with minimal effect on pre-existing implants

摘要

An method is provided for fabricating a metal silicide upon a semiconductor topography. The method advantageously performs the anneal cycles at a substantially lower temperature. By employing a high pressure anneal chamber, temperature equilibrium is achieved across the semiconductor topography and especially in small silicide formation areas. The higher pressure helps ensure thermal contact of heated, flowing gas across relatively small geometries in which silicide is to be formed. Substantial metal silicide formation can occur at the higher pressures even under relatively lower temperature conditions. The lower temperature process helps ensure that pre-existing implant regions remain at their initial position. The present metal silicide process and lower temperature anneal is therefore well suited to avoid impurity migration problems such as, for example, threshold skew, parasitic junction capacitance enhancement, and gate oxide degradation.