Patent ID: 7147748

Claim:
A plasma processing method to subject substrates to plasma processing in lots having: a light-receiving part for monitoring a plasma emission in a 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; and a controller for controlling an operation of said plasma processing apparatus; the method comprising: step (A) of determining a difference (D ij =P ij −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; step (B) of determining an average, a difference of minimum and maximum, and a standard deviation of (D ij ) for all substrates in a lot; and step (C) of comparing the average, the difference of minimum and maximum, and the standard deviation, as determined, with preset thresholds to determine an end point of seasoning.