Method for fabricating n-type metal oxide semiconductor transistor

A method for fabricating an NMOS transistor, comprising:

• forming a gate structure on a substrate;
• forming two source/drain regions in the substrate and respectively located at two sides of the gate structure;
• performing a first pre-amorphous implantation (PAI) process to implant a first amorphizing substance into the two source/drain regions;
• performing a stress memorization technique (SMT) process to form a strained channel, wherein the strained channel is located in the substrate and below the gate structure, and at least one of the source/drain regions is formed with a dislocation;
• performing a second PAI process to implant a second amorphizing substance into the two source/drain regions, so as to form two amorphous portions respectively in the two source/drain regions;
• and
• performing a self-aligned silicide process to form a silicide on the two source/drain regions.