Patent ID: 7666480

Claim:
A method for forming a silicon nitride film on a wafer in a PECVD chamber, comprising: pre-coating the PECVD chamber with a silicon nitride film to form a protection layer; inserting a wafer into the PECVD chamber to deposit the silicon nitride film on the wafer; adjusting a time for depositing the silicon nitride film in the PECVD chamber so as to deposit the silicon nitride film with a uniform thickness on each one of a predetermined number of wafers; and cleaning the PECVD chamber with RE plasma after depositing the silicon nitride film on the predetermined number of wafers, wherein, in the adjusting of the time for depositing the silicon nitride film, a deposition time SDT for each wafer is calculated by SDT=(10*T)/(bX 2 +cX +d), wherein X is an index that is incremented for each calculation of SDT until the predetermined number of wafers are processed, T is a standard deposition time, and b, c, and d are constants.