System and method for determining endpoint in etch processes using partial least squares discriminant analysis in the time domain of optical emission spectra
US6830939B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 28, 2002 |
| Grant date | Dec 14, 2004 |
| Priority date | — |
| Expiry date | Mar 2, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J37/32963
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The present invention is directed to a system, method and software product for creating a predictive model of the endpoint of etch processes using Partial Least Squares Discriminant Analysis (PLS-DA). Calibration data is collected from a calibration wafer using optical emission spectroscopy (OES). The data may be non-periodic or periodic with time and periodic signals may be sampled synchronously or non-synchronously. The OES data is arranged in a spectra matrix X having one row for each data sample. The OES data is processed depending upon whether or not it is synchronous. Synchronous data is arranged in an unfolded spectra matrix X having one row for each period of data samples. A previewed endpoint signal is plotted using wavelengths known to exhibit good endpoint characteristics. Regions of stable intensity values in the endpoint plot that are associated with either the etch region or the post-etch region are identified by sample number. An X-block is created from the processed OES data samples associated with the two regions of stable intensity values. Non-periodic OES data and asynchronously sampled periodic OES data are arranged in a X-block by one sample per row. Synchronou…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.