Development of a Magnetic Levitation Wafer Handling Robot Transfer System with High-Accuracy and High-Cleanliness: Experimental Evaluation

Abstract

Magnetic levitation can reduce particulate contamination that occurs during wafer transportation in the semiconductor manufacturing process. This technology radically eliminates contact between the wafer and the transport system, reducing friction, wear, and particle generation. Therefore, it is suitable for achieving high cleanliness in the ultra-fine line-width semiconductor production process and solving the need for particle removal in a vacuum environment. In this study, the roller and linear motion guide components of the wafer transfer system were replaced with a magnetic levitation module, and a robot arm was installed on top to transport a single wafer. A posture controller and a current controller were designed, and test equipment simulating the wafer transfer system was also manufactured and tested. Regarding mover and system identification, a sine sweep test was performed on the motion axis of the five degrees of freedom. Through the obtained system identification, it was possible to design the posture controller more precisely. Moreover, through levitation in standstill experiments and high-speed operation experiments, the wafer transport system can be used to verify dust-free high-speed transport and accurate positioning performance.

Optimal Control for a Superconducting Hybrid MagLev Transport System with Multirate Multisensors in a Smart Factory

“…The proposed output feedback compensator combines the measured values of sensors with multirate sampling times and minimizes the H 2 norm of the closed-loop system [ 8 ]. The proposed H 2 compensator is designed for a lifted sensor networked system (9) with exogenous input, and output, and is applied to a multirate system (2).…”

“…In the in-track magnetic levitation system considered in this paper, all sensors are installed on the track rather than on the vehicle, so multiple heterogeneous sensors are installed along the vehicle’s transport path [ 2 , 8 , 9 ]. Controlling system inputs requires processing and implementing multiple measured outputs from these sensors simultaneously.…”

“…Controlling system inputs requires processing and implementing multiple measured outputs from these sensors simultaneously. Various sensors are applied inside and outside the track and vehicle to measure output signals such as current, voltage, levitation gap, and propulsion position [ 2 , 8 , 9 ]. Typically, the control performance of the entire system is governed by the slowest measurement sensor among multiple heterogeneous sensors [ 18 , 19 , 20 ].…”

“…The studied MagLev systems are being considered to replace the existing belt-type conveyor system in the semiconductor and OLED display panel production process [3][4][5][6][7]. These processes require a highly clean environment because fine dust has a significant impact on production yield [8,9]. Therefore, the MagLev conveyor system, which does not generate contact dust, is more suitable than the traditional electric motor conveyor belt system [9,10].…”