Particle Sizing and Identification Through Advanced Light Scatter Techniques

Light scatter has been used to map and size particles on silicon wafers for many years, producing accurate maps of particle position and giving an indication of particle size, but do not reveal any information about particle composition. Today's technology is limited by noise, precluding detection of the smallest particles of interest. Present instruments are not adequate for the next generation of semiconductor devices. Experimental and theoretical studies indicate that more information can be obtained from light scattered by particles than is presently being utilized. Through a combination of measurements and modeling, it should be possible to identify an optimum configuration (geometry, wavelength, polarization, etc.) for a scattering instrument. Work includes experimental verification of theoretical scatter models, noise analysis, development of numerical models, selection of potential instrument configurations, comparison and optimization of configurations and development of specifications for a prototype instrument. If successful, this approach will lead to a prototype instrument capable of detecting and classifying particles as small as 0.06 um on silicon wafers. This will support the goals of the National Technology Roadmap for Semiconductors through the 0.18 um process generation.