As one of the core units of a lithography machine, the ultra-precision wafer stage is mainly responsible for achieving functions such as fast scanning, wafer loading/unloading, precise positioning, leveling, and focusing. Currently, most mature solutions adopt a VME parallel bus architecture to build ultra-precision wafer stage control systems. However, as system performance requirements increase, the VME bus and its corresponding processors can no longer meet the demands, thus necessitating the design of a new type of wafer stage control system.

2.1 System Design Requirements Analysis

2.1.1 Wafer Stage System Overview

As shown in Figure 2-1, the wafer stage of a step-and-scan projection lithography machine is mainly composed of three major parts: the measurement wafer stage, the exposure wafer stage, and the reticle stage. A projection system is located between the wafer stage and the reticle stage. During the exposure process, the control system needs to perform high-precision position measurements of the wafer stage and reticle stage using laser interferometers, and control and adjust multiple degrees of freedom to achieve precise positioning motion of the wafer stage.

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