An apparatus and method for detection of a feature etch completion within an etching reactor. The method includes determining a correlation matrix by recording first measured data regarding a first etch process over successive time intervals to form a first recorded data matrix, assembling a first endpoint signal matrix using target endpoint data for a specific etch process, performing a partial least squares analysis on the recorded data matrix and the first endpoint signal matrix to refine the recorded data matrix, and computing a correlation matrix based upon the refined recorded data matrix and the first endpoint signal matrix. The method further includes performing a second etch process to form a second recorded data matrix. The correlation matrix and the second recorded data matrix are analyzed to determine whether an endpoint of the second etch process has been achieved.