System and Method for the Identification of Chemical Mechanical Planarization Defects

• US 20050223805A1
• Filed: 04/08/2005
• Published: 10/13/2005
• Est. Priority Date: 04/08/2004
• Status: Abandoned Application

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Das, Tapas K., Sikder, Arun K., Kumar, Ashok, Ganesan, Rajesh
• Application Number:
  US10/907,633
• Publication Number:
  US 20050223805A1
• Time in Patent Office: Days
• US Class Current: 73/587
• CPC Class Codes: B24B 37/005 Control means for lapping machines or devices
• CPC Class Codes: B24B 49/003 involving acoustic means
• CPC Class Codes: G01N 2291/0231 Composite or layered materials
• CPC Class Codes: G01N 2291/2632 flat
• CPC Class Codes: G01N 2291/2697 Wafer or (micro)electronic parts
• CPC Class Codes: G01N 29/043 in the interior, e.g. by shear waves
• CPC Class Codes: G01N 29/12 by measuring frequency or resonance of acoustic waves measuring frequency or resonant frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04, G01H13/00; acoustic resonators G10K11/04; vibration or shock testing of structures G01M7/00
• CPC Class Codes: G01N 29/14 using acoustic emission techniques echo of particles G01N29/046; measuring mechanical vibrations or acoustic waves in solids in general G01H1/00
• CPC Class Codes: G01N 29/348 with frequency characteristics, e.g. single frequency signals, chirp signals measuring frequency of mechanical vibrations or acoustic waves in general G01H1/06, G01H3/04; measuring frequency or analysing frequency spectra G01R23/00
• CPC Class Codes: G01N 29/42 by frequency filtering or by tuning to resonant frequency
• CPC Class Codes: G01N 29/4427 with stored values, e.g. threshold values
• CPC Class Codes: G01N 29/4445 Classification of defects
• CPC Class Codes: G01N 29/46 by spectral analysis, e.g. Fourier analysis or wavelet analysis spectral signal processing per se G06F17/14

Abstract

The present invention presents a novel application of a wavelet-based multiscale method in a nanomachining process chemical mechanical planarization (CMP) of wafer fabrication. The invention involves identification of delamination defects of low-k dielectric layers by analyzing the nonstationary acoustic emission (AE) signal collected during copper damascene (Cu-low k) CMP processes. An offline strategy and a moving window-based strategy for online implementation of the wavelet monitoring approach are developed.

Claims

1. A method of detecting a delamination defect in a chemical mechanical planarization process, the method comprising the steps of:

sampling acoustic emission signals of the chemical mechanical planarization process, the acoustic emission signals associated with at least one preselected frequency or preselected frequency band; and

performing wavelet based multiresolution analysis of the sampled acoustic emission signals to detect a delamination defect in the chemical mechanical planarization process.

2. The method of claim 1, wherein the step of performing wavelet based multiresolution analysis of the sampled acoustic emission signals further comprises the steps of:

wavelet decomposing the acoustic emission signals;

identifying a plurality of wavelet coefficients of the acoustic emission signals;

thresholding the wavelet coefficients;

reconstructing the details from the thresholded wavelet coefficients in the time domain at each of the at least one preselected frequency or preselected frequency bands; and

observing the details of the reconstruction to detect a delamination defect in the chemical mechanical planarization process.

3. The method of claim 2, wherein the step of wavelet decomposing the acoustic emission signals further comprises wavelet decomposing to six levels of decomposition.

4. The method of claim 2, wherein the step of wavelet decomposing the acoustic emission signals further comprises wavelet decomposing the acoustic emission signals utilizing a moving wavelet window.

5. The method of claim 1, wherein the method of detecting a delamination defect in a chemical mechanical planarization process is performed ex situ.

6. The method of claim 1, wherein the method of detecting a delamination defect in a chemical mechanical planarization process is performed in situ.

7. The method of claim 1, further comprising the steps of:

sampling in-control acoustic emission signals to obtain in-control data;

establishing a standard for the wavelet based multiresolution analysis of the sampled acoustic emission signals utilizing the in-control data.

9. The method of claim 1, wherein the analyzer further includes:

a wavelet decomposer to decompose the acoustic emission signals;

a thresholder to apply thresholds to a plurality of wavelet coefficients of the decomposed acoustic emission signals;

a reconstructor to reconstruct the details from the thresholded wavelet coefficients in the time domain at each of the at least one preselected frequency or preselected frequency bands; and

a detector to observe the details of the reconstruction to detect a delamination defect in the chemical mechanical planarization process.

10. The method of claim 2, wherein the decomposer further comprises a moving wavelet window.

11. The method of claim 1, wherein the acoustic transducer and the analyzer are operated ex situ.

12. The method of claim 1, wherein the acoustic transducer and the analyzer are operated in situ.

13. The method of claim 1, further comprising:

an in-control data sampler to sample in-control acoustic emission signals to obtain in-control data;

a standards establisher to establish a standard for the wavelet based multiresolution analysis of the sampled acoustic emission signals utilizing the in-control data.

15. The method of claim 1, wherein the means for performing wavelet based multiresolution analysis further comprises:

means for wavelet decomposing the acoustic emission signals;

means for thresholding to a plurality of wavelet coefficients of the decomposed acoustic emission signals;

means for reconstructing the details from the thresholded wavelet coefficients in the time domain at each of the at least one preselected frequency or preselected frequency bands; and

means for observing the details of the reconstruction to detect a delamination defect in the chemical mechanical planarization process.

16. The method of claim 2, wherein the means for wavelet decomposing the acoustic emission signals further comprises means for applying a moving wavelet window.

17. The method of claim 1, wherein the means for sampling acoustic emission signals the means for performing wavelet based multiresolution analysis are performed ex situ.

18. The method of claim 1, wherein the means for sampling acoustic emission signals the means for performing wavelet based multiresolution analysis are performed in situ.

19. The method of claim 1, further comprising:

means for sampling in-control acoustic emission signals to obtain in-control data;

means for establishing a standard for the wavelet based multiresolution analysis of the sampled acoustic emission signals utilizing the in-control data.

8. A system for detecting a delamination defect in a chemical mechanical planarization process, the system comprising:

an acoustic transducer positioned proximate to a contact region between a wafer and a polishing pad of the chemical mechanical planarization process, the acoustic transducer to sample acoustic emission signals associated with at least one preselected frequency or preselected frequency band; and

an analyzer performing wavelet based multiresolution analysis of the sampled acoustic emission signals to detect a delamination defect in the chemical mechanical planarization process.

14. A system for detecting a delamination defect in a chemical mechanical planarization process, the system comprising:

means for sampling acoustic emission signals associated with at least one preselected frequency or preselected frequency band; and

means for performing wavelet based multiresolution analysis of the sampled acoustic emission signals to detect a delamination defect in the chemical mechanical planarization process.