Method for forming silicide

A method for forming silicide on a semiconductor wafer, the semiconductor wafer comprising a doped silicon layer on a predetermined area of the semiconductor wafer, a metal layer positioned on the doped silicon layer, and a first barrier layer covering the metal layer, the method comprising:

• performing a first rapid thermal processing (RTP) step to make portions of the metal layer react with silicon inside the doped silicon layer so as to form a transitional silicide;
• removing the first barrier layer and the portions of the metal layer that have not reacted with silicon;
• forming a second barrier layer on the transitional silicide, wherein the second barrier layer is used to prevent impurities in the doped silicon layer from outgassing during a second rapid thermal processing step;
• performing the second rapid thermal processing (RTP) step to make the transitional silicide react with portions of the doped silicon layer so as to form the silicide;
• removing the second barrier layer;
• and
• forming a dielectric layer on the silicide.