Work

Synchronization‐Performance‐Oriented Frequency‐Domain Iterative Learning Control for Wafer and Reticle Stages

Year: 2026

Type: article

Abstract: ABSTRACT The synchronization accuracy between the wafer stage and reticle stage in lithography is critical to overlay and critical dimension uniformity. Existing iterative learning control (ILC) methods indirectly optimize synchronization via time‐domain errors, failing to balance low‐frequency tracking accuracy and high‐frequency noise suppression; thus, they cannot achieve optimal synchronization performance. To address this issue, this paper proposes a synchronization performance‐oriented frequency‐domain ILC approach, which embeds a comprehensive frequency‐domain index integrating Moving Average and Moving Standard Deviation into the ILC learning law. An adaptive learning gain is designed to balance convergence speed and disturbance rejection. Rigorous theoretical analyses confirm the method's asymptotic convergence under deterministic conditions and almost sure convergence under stochastic disturbances. Simulation results demonstrate that the proposed method outperforms two representative ILC methods, achieving faster convergence, higher accuracy with a maximum synchronization error of 0.1117 nm, and strong robustness.

Source: Asian Journal of Control

DOI: 10.1002/asjc.70230

Authors: Xin Zhou, Yuejing Qi, Zhipeng Wu, Wei Qi, Tianwei Xu

Institutions: Chinese Academy of Sciences, Institute of Microelectronics, University of Chinese Academy of Sciences

Language: English

Topic: Iterative Learning Control Systems

Subfield: Control and Systems Engineering

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $2,850

Funder: National Science and Technology Major Project