Measurement of nanoparticles on parts: Figures of merit of a liquid-borne particle counter

An effective way to evaluate surface cleanliness of semiconductor tool components (parts) is to measure surface particles extracted from parts by liquid-borne particle counter (LPC). In this work, a previously published framework for evaluating commercial LPCs was extended for evaluation of LPC counting particles smaller than 200 nm and with <;100% counting efficiency. Key parameters such as counting accuracy, precision, stability, and limit of detection, etc., of a RION KS-42AF were evaluated. Experiments based on PSL count standards indicated that counting accuracy is low at <;70% if counting efficiency was not considered. After compensated with counting efficiency, the counter under evaluation showed ≤3% counting error and imprecision. The linear dynamic range is from 15 to 1,000 particles/mL.