Patent Document ID: 20140106477
Application ID: 14056059
Patent Flag: 0

Claim One:
1. A method for determining etch process endpoint data, comprising: in a plasma etch processing tool, performing k plasma etch process runs, where k is an integer greater than zero, each of the k plasma etch process runs comprising steps of: loading a substrate to be processed into the plasma etch processing tool, the plasma etch processing tool comprising a spectrometer having a detector comprising m pixels, each pixel corresponding to a different light wavelength; igniting a plasma in the plasma etch processing tool; collecting n optical emission spectroscopy (OES) data sets sampled at equal time intervals during each of k plasma etch process runs, each of the n optical emission spectroscopy (OES) data sets comprising m pixel intensities corresponding to m pixels of the spectrometer; forming an n×m optical emission spectroscopy (OES) data matrix [X] for each of k plasma etch process runs, each time sample occupying a row of the optical emission spectroscopy (OES) data matrix [X], the columns of the optical emission spectroscopy (OES) data matrix [X] corresponding to pixels of the spectrometer; computing an n×m average optical emission spectroscopy (OES) data matrix [X] avg , wherein each element of the average optical emission spectroscopy (OES) data matrix [X] avg is computed as an average of elements of optical emission spectroscopy (OES) data matrices [X] for the k etch process runs; filtering noise from the average optical emission spectroscopy (OES) data matrix [X] avg ; truncating each optical emission spectroscopy (OES) data matrix [X] to eliminate optical emission spectroscopy (OES) data acquired during plasma startup and for times beyond an etch process endpoint; truncating the average optical emission spectroscopy (OES) data matrix [X] avg to eliminate averaged optical emission spectroscopy (OES) data acquired during plasma startup and for times beyond the etch process endpoint; calculating an n x m mean optical emission spectroscopy (OES) data matrix [S avg ], wherein each element of each of the columns of the mean optical emission spectroscopy (OES) data matrix [S avg ] is computed as an average of each of n pixel intensities of the average optical emission spectroscopy (OES) data matrix [X] avg over the column of the average optical emission spectroscopy (OES) data matrix [X] avg ; subtracting the mean optical emission spectroscopy (OES) data matrix [S avg ] from optical emission spectroscopy (OES) data matrices [X], to de-mean the optical emission spectroscopy (OES) data, and performing a principal component analysis [T]=([X] [i] −[S avg ])[P] on the de-meaned and non-normalized subtraction results, to obtain a transformed optical emission spectroscopy (OES) data vector [T] and principal component weights vector [P]; storing the mean optical emission spectroscopy (OES) data matrix [S avg ] for later use in in-situ determination of an etch process endpoint; storing the principal component weights vector [P] for later use in in-situ determination of the etch process endpoint.