Connecting System Identification and Robust Control for Next-Generation Motion Control of a Wafer Stage

Abstract

Next-generation precision motion systems are lightweight to meet stringent requirements regarding throughput and accuracy. Such lightweight systems typically exhibit lightly damped flexible dynamics in the controller cross-over region. State-of-the-art modeling and motion control design procedures do not deliver the required model complexity and fidelity to control the flexible dynamical behavior. The aim of this paper is to develop a combined system identification and robust control design procedure for high performance motion control and apply it to a wafer stage. Hereto, new connections between system identification and robust control are employed. The experimental results confirm that the proposed procedure significantly extends existing results and enables next-generation motion control design.

Constrained Iterative Feedback Tuning for Robust Control of a Wafer Stage System

“…In this section, the control tuning problem of wafer scanners in general and wafer stages in specific is introduced; see also [6] for an historical perspective and [33] for an overview of present control challenges. The section is divided into five parts: (a) wafer scanners, (b) motion control context, (c) wafer stage plant description, (d) wafer stage feedback control, and (e) performance of wafer scanners and stages.…”

“…For clarity of presentation, only the scanning y-direction is subject to further (constrained) IFT optimization, see [16], [17], [35] for examples of MIMO IFT and [33], [45] for MIMO model-based counterparts.…”

“…Model-based approaches refer to the system first being modeled, for example through system identification. Modeling, however, can be a time-consuming and difficult process [19], [33]. In this regard, direct data-driven approaches, see, e.g.…”

A compliance feedforward scheme for a class of LTV motion systems

“…The required forces to be applied during operation are therefore increasingly higher, which increases the demands on actuators, amplifiers, and cooling. The resulting force density and heat generation necessitated to accelerate the mass therefore becomes increasingly infeasible, which prompts for more flexible lightweight designs [14].…”

Decoupling Control Method for High-Precision Stages using Multiple Actuators considering the Misalignment among the Actuation Point, Center of Gravity, and Center of Rotation

“…High-precision scan stages play an important role in the manufacturing processes for semiconductors and liquid crystal displays (1) (2) . In these applications, high-precision stages have to control six degrees of freedom (DOFs: x, y, z, θ x , θ y , and θ z ) (3) .…”