For non-silica slurries, LNS, DLS, and SEM measurements have geometric mean diameters which can vary from another by 10 nm or more. We find also that the LNS can quantify multimodal size distributions. LNS measurements are more repeatable than DLS measurements, and for 4 silica slurries, LNS distributions are in better agreement with SEM measurements than DLS. LNS measurements are compared to size distributions inferred from electron microscopy (SEM), and dynamic light scattering (DLS). We evaluate the potential of an aerosol technique, namely differential mobility analysis (in a liquid nanoparticle sizer, LNS, system) to characterize size distributions of CMP slurries. Key to CMP performance is the size distribution of the particles. These clear advantages make the NanoFlowSizer the ideal solution for inline or online measurements, providing continuous real-time process feedback on nanoparticle size characteristics, a powerful Process Analytical Tool.In chemical mechanical planarization (CMP), a particle slurry is used in polishing semiconductor wafers. The flow corrected auto-correlation functions can be processed into reliable particle size information. The Flow correction algorithms of the NanoFlowSizer make use of the known flow velocity pattern of a laminary flow, which allows direct correction (Right) for flow rate as long as a laminary flow is maintained. As a consequence of flow the obtained auto-correlation functions will deviate (show a steeper decay) when flow rates become larger (Middle). Figure: Left: For measurements in flow, particles close to the edge (glass interface for measurement) show lower flow rates compared to particles further away from the edge.
#DYNAMIC LIGHT SCATTERING SIZE DISTRIBUTION BY NUMBER SOFTWARE#
The XsperGo software is able to correct for flow effects on measurements using the relevant Brownian motion information. As spatially resolved data are available, the NanoFlowSizer is capable of fitting and distinguishing particle movements caused by flow and Brownian motion. The measurement and processing of the data into particle size information, such as z-average, PSD (particle size distribution) and PDI (poly dispersity index), takes place within 10s.Ĭonventional DLS requires the sample to be at rest. Right: Particle size information is obtained by processed single scattered light data only. Middle: the obtained auto-correlation functions originated form single scattered light are automatically selected, for processing of particle size information, while those related to multiple scattering are automatically discarded. When multiple scattering occurs, the applied algorithms of the NanoFlowSizer will detect automatically at which depth (pathlength) this occurs. As a result, obtained data of highly turbid samples is automatically corrected for multiple scattered light (since multiple scattered light will not be used for adequate particle size analysis in DLS).įigure: Left: the chance that unwanted multiple scattering occurs increases with the turbidity level of the sample and the pathlength of the light. The spatially resolved data in combination with smart algorithms allows the NanoFlowSizer to distinguish single from multiple scattered light, which is fully automated within the XsperGo software. Nanoparticle analysis of highly concentrated and optically turbid samples
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