Patent ID: 7147747

Claim:
A plasma processing apparatus having a process chamber in which substrates are subjected to plasma processing in lots comprising; a light-receiving part for monitoring a plasma emission in said process chamber; a spectrometer unit for performing a spectrometry on said plasma emission and to convert the same into a multi-channel signal; an arithmetic unit for performing principal component analysis on the multi-channel signal for each substrate to obtain an average of principal component scores (P ij for j-th substrate of i-th lot); a database for storing a filter vector for obtaining the principal component scores; first means to determine a difference (D i,j =P i,j −P i-1,j ) of average principal component scores of a substrate in a lot compared to that of a substrate in an identical position in the previous lot; second means to determine an average, a difference of minimum and maximum, and a standard deviation of (D ij ) for all substrates in a lot; third means to compare the average, the difference of minimum and maximum, and the standard deviation, as determined, with preset thresholds to determine an end point of seasoning; and a controller for controlling an operation of said plasma processing apparatus.