Lithography Stage Control with Mode-Switched Trajectory Feedback

Solution Overview

Problem

Current lithographic apparatuses face challenges in achieving high throughput due to limitations in controlling repetitive movements and accelerations during pattern projection on substrates.

Innovation Solution

A controller system is introduced, comprising a feedforward controller and a feedback controller system with an integrator, trajectory generator, and selector. This system operates in two control modes, selecting between the trajectory generator output and the integrator output based on the reference state signal, to optimize movement control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional feedback controller is used to control the stage movements, then the position control can be maintained, but the settling time is prolonged and overshooting occurs during acceleration and deceleration phases

Engineering Contradiction:

Improveposition control accuracyVSAvoidsettling time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The trajectory generator predicts the ideal trajectory in advance based on the reference trajectory and system dynamics model. By calculating the optimal control signal beforehand using predictive control algorithms, the system prepares the ideal path before execution, enabling faster response and reduced settling time without sacrificing position accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The controller dynamically switches between different control modes (manual mode, automatic mode with trajectory generator, and automatic mode with integrator) based on operational requirements. This dynamic adaptability allows the system to optimize performance for different phases of operation, reducing overshooting during acceleration/deceleration while maintaining accuracy during steady-state scanning.

Inventive Principle:

Principle #15Dynamics

2Manufacturing precision

If the controller uses integrator output for continuous correction, then position accuracy is maintained, but the system responds slowly to changes in acceleration and deceleration

Engineering Contradiction:

Improveposition accuracyVSAvoidresponse speed

Core Design Contradiction:

Manufacturing precisionVSSpeed

Solution Approach 1:

The controller dynamically switches between different control modes (manual mode, automatic mode with trajectory generator, and automatic mode with integrator) based on operational requirements. This dynamic adaptability allows the system to optimize performance for different phases of operation, reducing overshooting during acceleration/deceleration while maintaining accuracy during steady-state scanning.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes control parameters dynamically by switching between integrator gain and trajectory generator output based on the operational phase. During acceleration and deceleration phases, the trajectory generator provides aggressive correction for fast response. During steady-state scanning, the integrator provides continuous fine-tuning for high precision, thus adapting parameters to match operational needs.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If the lithographic apparatus performs frequent accelerations and decelerations for scanning movements, then substrate coverage is improved, but the throughput is reduced due to prolonged settling time

Engineering Contradiction:

Improvesubstrate coverage capabilityVSAvoidthroughput

Core Design Contradiction:

Adaptability or versatilityVSProductivity

Solution Approach 1:

The trajectory generator predicts the ideal trajectory in advance based on the reference trajectory and system dynamics model. By calculating the optimal control signal beforehand using predictive control algorithms, the system prepares the ideal path before execution, enabling faster response and reduced settling time without sacrificing position accuracy.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The predictive trajectory generator continuously calculates the optimal control signal based on real-time system state and reference trajectory, ensuring uninterrupted and smooth stage movements. This continuous prediction and correction mechanism eliminates idle settling time between scanning movements, maintaining continuous productive action while improving substrate coverage capability.

Inventive Principle:

Principle #20Continuity of useful action

Data Source

PatentUS20250116944A1Lithographic apparatus controller system

Publication Date: 2025.04.10 ASML NETHERLANDS BV

AI summary

A controller system is configured to control a plant and comprising a feedforward controller to provide, based on a reference state signal, a feedforward signal to the plant, and a feedback controller system to provide a feedback signal to the plant, based on a difference between the reference state signal and a plant state signal representing an actual state of the plant. The feedback controller system comprises an integrator, a trajectory generator, and a selector. The feedback controller system is configured to operate as a function of the reference state in a first control mode or a second control mode, wherein the feedback controller system, in the first control mode, operates the selector to select the trajectory generator output signal generated by the trajectory generator, and wherein the feedback controller system, in the second control mode, operates the selector to select the integrator output signal generated by the integrator.