No abstract

As chemical mechanical planarization (CMP) enables local and global planarization over a wafer surface by the combined effects of chemical and mechanical interactions, process monitoring is becoming an increasingly important in-situ methodology for process control. According to the materials and process, signal characteristics were distinguishable between material and process. In this study, an acoustic emission (AE) sensor was used to measure the abrasive and molecular-scale phenomena during CMP. An AE signal was acquired using rotational equipment and adapted to two types of equipment. First, a wireless AE system consisting of wireless modules using Bluetooth was used. This system was suitable for acquiring signals in rotational equipment. However, a wireless AE system could be acquired with only Root Mean Square(RMS) signals. Second, mercury slip-ring (wired) AE systems that were suitable for rotational equipment and the acquisition of raw signals were used. The acquired raw signals could be analyzed by a Fast Fourier Transform (FFT) for abrasive and molecular-level phenomena in the CMP process. The AE signal parameters including the AE RMS, frequency, and amplitude were analyzed for abrasive and molecular-level phenomena in the CMP process. The authors analyzed the AE signals for changes in the materials and CMP process.

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The existing vibration serviceability evaluation of bridges focused on the structure. To evaluate vibration serviceability from a user perspective, vibration level felt by pedestrians was surveyed in a steel composite wooden bridge and analyzed to present the vibration serviceability evaluation method felt by the pedestrian. Such vibration was classified according to the walking type using the modified Reiher-Meister vibration curve, the existing evaluation method, and rolling up and down and rolling left and right in place were the most overestimated. As vibration is influenced by individuals, additional research is needed.

The vibration acceleration response and excellent frequency generated by pedestrian’s walking type of the steel composite wooden bridge were measured and analyzed. Based on the modified Reiher-Meister vibration curve, vibration influence evaluation on the structural perspectives of the pedestrian bridge was performed. The pedestrian’s walking types were divided into walking, running, rolling, and shaking, and eight experimental cases were set up by combining them with the number of users and moving direction. A total of 37 measurements were made. To evaluate the vibration serviceability of pedestrian bridges, the pedestrian’s walking type must be considered, and a standardized study on the pedestrian’s walking type will be necessary in the future.