Method and apparatus for measurement of particle size distribution in substantially opaque slurries
US6246474A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 29, 1998 |
| Grant date | Jun 12, 2001 |
| Priority date | — |
| Expiry date | Apr 29, 2018 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61B2090/363
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A very sensitive particle distribution probe uses special processing including a modified Twomey/Chahine iterative convergence technique and a specially constructed sample cell to obtain particle size distribution measurements from optically dense slurries, such as the slurries used in the semiconductor industry for chemical mechanical planarization. Spectral transmission data is taken over the spectral range of 0.20-2.5 microns, utilizing specially constructed, chemically resistant sample cells of 50-250 microns thickness, and miniature, fixed grating, linear detector array spectrometers. At wavelengths greater than 1 micron, the preferred design utilizes InGaAs linear detector arrays. An ultrasonic disrupter can be employed to breakup harmless soft agglomerates. In addition to direct particle size distribution measurement, the invention described here could be used to detect other fundamental causes of slurry degradation, such as foaming and jelling. The probe accomplishes continuous, real time sampling of undiluted slurry. A three-position chopper allows automated operation in an industrial environment without the need for frequent reference spectra, which would require taking t…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.