System and method for online end point detection for use in chemical mechanical planarization

A computer-implemented process for identifying an endpoint of polishing in a chemical mechanical planarization process, the method comprising the steps of:

• wavelet decomposing the coefficient of friction data acquired from the chemical mechanical planarization process to obtain a plurality of wavelet coefficients;
• testing an energy content of each of the plurality of wavelet coefficients to identify a plurality of wavelet coefficients having a significant frequency level;
• applying thresholding rules to the plurality of wavelet coefficients identified as having a significant frequency level to obtain a plurality of thresholded wavelet coefficients having a significant frequency level;
• reconstructing a plurality of time-domain wavelet details from the plurality of thresholded wavelet coefficients;
• and
• applying a sequential probability ratio test for variance on the reconstructed time-domain wavelet details to identify the endpoint of polishing in the chemical mechanical planarization process.

A system for identifying an endpoint of polishing in a chemical mechanical planarization process, the system comprising:

• a decomposer for wavelet decomposing the coefficient of friction data acquired from the chemical mechanical planarization process to obtain a plurality of wavelet coefficients;
• an energy tester for testing an energy content of each of the plurality of wavelet coefficients to identify a plurality of wavelet coefficients having a significant frequency level;
• a thresholder for applying thresholding rules to the plurality of wavelet coefficients identified as having a significant frequency level to obtain a plurality of thresholded wavelet coefficients having a significant frequency level;
• a reconstructor reconstructing a plurality of time-domain wavelet details from the plurality of thresholded wavelet;
• and
• a sequential probability ratio tester for applying a sequential probability ratio test for variance on the reconstructed time-domain wavelet details to identify the endpoint of polishing in the chemical mechanical planarization process.

A computer readable storage medium executed by a processor for identifying an endpoint of polishing in a chemical mechanical planarization process, the computer readable storage medium comprising:

• a first plurality of binary values for wavelet decomposing the coefficient of friction data acquired from the chemical mechanical planarization process to obtain a plurality of wavelet coefficients;
• a second plurality of binary values for testing an energy content of each of the plurality of wavelet coefficients to identify a plurality of wavelet coefficients having a significant frequency level;
• a third plurality of binary values for applying thresholding rules to the plurality of wavelet coefficients identified as having a significant frequency level to obtain a plurality of thresholded wavelet coefficients having a significant frequency level;
• a fourth plurality of binary values for reconstructing plurality of time-domain wavelet details from the plurality of thresholded wavelet;
• and
• a fifth plurality of binary values for applying a sequential probability ratio test for variance on the reconstructed time-domain wavelet details to identify the endpoint of polishing in the chemical mechanical planarization process.