抄録
A new measuring method for particles of nanometer (nm)-order size on a Si (Silicon) wafer has been developed using a light-scattering method. In this method, a measuring system was developed to detect particles of nm-order size, by scanning the laser spot on the surface of a Si wafer. In this study, to improve the detection sensitivity for particle diameters, we attempted to discriminate detected voltage signals including the detected signal for particles and the measured noise signal for the surface of Si wafer on the photo multiplier tube (PMT). Consequently, the detection sensitivity was improved for particle diameters down to 15nm from 24nm. Results indicate that the detection sensitivity depends on the roughness of the measuring surface, and the maximum detectable diameter is theoretically determined to be 5nm. Furthermore, we attempted to measure a standard particle (polystyrene latex: PSL) adhering on the Si wafer surface, the particle diameter of which is known, using the developed measuring system and particle counting technique. As a result, it was verified that this system can measure particle diameters smaller than 80nm, which are difficult to detect using the particle counter. Moreover, to evaluate the developed measuring system, we attempted to measure particles on the surface of a bare Si wafer using this measuring system and the particle counter. Consequently, it was verified that this measuring system can detect particles of nm-order size on the Si wafer.
