Slot-die coating is a method of coating a wide layer of thin film on a substrate. It has the advantages of large-area coating with high reproducibility and uniform thickness. For this reason, it has been widely applied in various industrial manufacturing fields. To secure higher coating uniformity under various coating conditions, estimating and controlling the flow rate of the coating solution discharged to the substrate is crucial. In this study, a practical gravimetric flow rate measurement method for slot-die coating uniformity evaluation has been introduced. The gravimetric method is a technique for accurately and quickly estimating the flow rate through the mass change over time using a precision weighing balance. We analyzed the measurement principle and errors caused by fluid mechanics such as hydrodynamic force or capillary force. The dynamic properties based on fluid viscosity were also evaluated for flow rates from 5 to 50 μL/s. The repeatability of the fabricated measurement system was ~1.5 μL/s. Finally, it was confirmed that the settling time for high-viscosity fluid could be advanced by 56.4% through multi-step feedforward control.

A theoretical and numerical FSI approach is used to predict the mass flow in a Coriolis flow meter. By comparing with the experimental results according to the relationship between mass flow and the time phase difference at the inlet and outlet of the tubes, the authors could determine the reliability of the present results from a theoretical and numerical approach in this paper. The mass flow has a linear relationship with the time phase difference, which is a unique parameter to measure true mass flow; therefore, for more precise measurement, it should be long enough to detect the signal within the given time resolution afforded by the detecting system and control system. Compact size and manufacturability, which are the important factors that decide the product competitiveness, should also be considered. In this paper, inversed triangle shaped and conventional U shaped Coriolis flow meters are designed, their time phase difference performances are predicted, and the results from experiments are well matched with the predicted results from the above-mentioned analysis.

Various chemicals are used for semiconductor process. In particular, the most important element in the etching and cleaning process is chemical liquid. An ultrasonic flow meter is used to monitor the supplying amount of chemical solution. If the ultrasonic flow meter contains bubble inside the liquid, measurement cannot be performed or measurement error will be occurred. In this research, the waveform was improved by zero-crossing processing so that the influence on measurement performance is negligible even if the bubble in the chemical solution is included. Consequently, the amplitude of the sound wave is attenuated. Existing flow meters monitor the amplitude value to determine the authenticity of the signal and to filter the noise. The improved method in this study distinguishes noise waves and monitors signal frequency. Flow measurement was carrying out even when the amplitude was resulting only less than 3% of input level volt. The system developed of this study has shown an exact measuring performance compared with the other make’s flow meters.