Abstract

Performance requirements of a higher throughput and accuracy in precision motion systems, such as wafer stage used in integrated circuit manufacturing, are ever increasing. The lightweight design, as one of the design methods, can results in less power consumption and less negative environmental impacts for the required high levels of acceleration. The aim of this research is to investigate the advantage of the lightweight design and to mitigate the negative effect caused by the flexible characteristics using an appropriate control method. In this paper, a prototype wafer stage is the analysis object. Since the mass of the horizontal drive motors accounts for a large proportion of the total mass of the wafer stage, a novel lightweight optimization frame based on the minimum motor mass is presented, while a Lorenz motor model based on finite element method (FEM) and artificial neural network (ANN) is firstly constructed. Then the controller adopting the PID with the maximum control bandwidth and pole placement method are designed. Through numerical analysis, the mass of the mover of the mover of this stage is reduced from 10.28 Kg to 6.078 Kg after lightweight optimization. Taking the Moving Average (MA) and Moving Standard Deviation (MSD) of the servo error in Z-direction as the control index, a closed-loop simulation result shows that the lightweight wafer stage can separately fulfil the requirement of the MA and MSD of the servo error in z-direction within 20nm and 30nm just as the current rigid-body wafer stage without the lightweight optimization.

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