Nanoimprint Lithography Alignment Control via Real-Time System Identification

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Solution Overview

Problem

Nanoimprint lithography faces limitations in alignment speed and accuracy due to non-linear dynamics between the template and substrate, caused by topography, material properties, and friction, leading to slow response and overshoot during field-to-field alignment.

Innovation Solution

A real-time feed-forward control method based on system identification is implemented, which assesses alignment errors, generates input signals for relative motion between the template and substrate, and adjusts motion control actions to reduce alignment errors, using a combination of feed-forward and feedback control signals to achieve smooth and rapid correction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional alignment methods are used to correct alignment error, then alignment accuracy can be achieved, but alignment speed is limited due to non-linear dynamics and friction

Engineering Contradiction:

Improvealignment accuracyVSAvoidalignment speed

Core Design Contradiction:

Measurement precisionVSSpeed

Solution Approach 1:

The system performs system identification in advance to characterize the non-linear dynamics and friction properties of the alignment mechanism. This preliminary characterization enables the feed-forward controller to pre-calculate compensation signals that account for hysteresis and friction effects before alignment operations begin, thereby improving both speed and accuracy without traditional trial-and-error adjustment

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback control using real-time alignment error measurements. The feedback controller continuously monitors the alignment state and adjusts control signals to correct deviations from the target position, ensuring high alignment accuracy while working in conjunction with the feed-forward controller to maintain rapid response

Inventive Principle:

Principle #23Feedback

2Productivity

If high alignment speed is implemented, then alignment throughput improves, but overshoot and oscillation occur due to non-linear dynamics

Engineering Contradiction:

Improvealignment throughputVSAvoidalignment stability

Core Design Contradiction:

ProductivityVSStability of the object's composition

Solution Approach 1:

System identification is performed beforehand to determine the dynamic characteristics and friction properties of the alignment system. This preliminary knowledge allows the feed-forward controller to pre-compensate for inertial effects and non-linear dynamics, enabling high-speed operation without overshoot or oscillation by anticipating system response behavior before commands are executed

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The control system dynamically adjusts control parameters based on the identified system characteristics. The feed-forward controller modifies control signals according to the non-linear friction model and dynamic parameters obtained from system identification, allowing the system to maintain stability across varying speeds and loads while maximizing alignment throughput

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If friction and hysteresis are present in the alignment system, then control precision deteriorates, but these effects are inherent to the mechanical system

Engineering Contradiction:

Improvecontrol precisionVSAvoidfriction and hysteresis effects

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The system transforms the harmful friction and hysteresis effects into useful information through system identification. By characterizing these non-linear effects, the feed-forward controller generates compensation signals that actively counteract friction and hysteresis, converting what were previously detrimental factors into opportunities for enhanced control precision through predictive compensation

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The feed-forward controller acts as an intermediary that processes alignment commands and modifies them based on the identified friction and hysteresis model. This intermediary layer pre-compensates for non-linear effects before commands reach the actuator, isolating the control system from the harmful influences of friction and hysteresis while maintaining accurate positioning

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS10409178B2Alignment control in nanoimprint lithography based on real-time system identification

Publication Date: 2019.09.10 CANON KK

AI summary

An imprint lithography alignment method includes assessing a first alignment error between the template and the substrate, generating a first input signal corresponding to a first relative motion between the template and the substrate, initiating the first relative motion between the template and the substrate via the first input signal, assessing an output signal corresponding to the first relative motion, comparing the first input signal and the output signal to yield a motion control action corresponding to a second relative motion between the template and the substrate, generating a second input signal corresponding to the second relative motion between the template and the substrate, initiating the second relative motion between the template and the substrate via the second input signal, and assessing a second alignment error between the template and the substrate, wherein a magnitude of the first alignment error exceeds a magnitude of the second alignment error.