Imprint Head Temperature Stabilization via RMS Current Control

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Solution Overview

Problem

Nanoimprint lithography faces challenges with misalignment and overlay errors due to thermal expansion and temperature-induced distortions in imprint heads, particularly during idle and intermittent periods when voice coil currents and temperature stability are compromised.

Innovation Solution

A temperature stabilizing apparatus and method that maintains a consistent root-mean-square electrical current through electromagnetic actuators during both idle and continuous imprinting states, ensuring consistent voice coil power and reducing thermal distortions by controlling the movement of the imprint head's moving plate and template position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the imprint head is kept idle for long periods, then energy consumption is reduced, but temperature instability increases causing misalignment and overlay errors

Engineering Contradiction:

Improveenergy consumptionVSAvoidalignment precision

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent applies periodic action by implementing a temperature stabilization system that periodically monitors and adjusts the imprint head temperature using thermal models and feedback control, rather than maintaining continuous heating. This allows the system to consume less energy during idle periods while still preventing temperature drift that would cause misalignment and overlay errors.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent changes the parameter control approach by dynamically adjusting heating power based on the operational state (idle vs. active) and predicted temperature drift. The system uses thermal expansion coefficients and predetermined thermal models to calculate required compensation, changing heating parameters proactively rather than maintaining constant power.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If continuous heating is applied to maintain temperature stability, then alignment precision is improved, but energy consumption increases

Engineering Contradiction:

Improvealignment precisionVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Instead of continuous heating, the system uses periodic temperature monitoring and model-based prediction to determine when heating is necessary. The control system periodically assesses temperature drift risk and applies heating only when needed, reducing energy consumption while maintaining alignment precision.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs preliminary action by using thermal models to predict temperature drift before it significantly affects alignment. Compensation heating is applied in advance based on predicted drift, preventing misalignment issues without requiring continuous high-level heating.

Inventive Principle:

Principle #10Preliminary action

3Speed

If high current is applied to voice coils for rapid positioning, then positioning speed is improved, but thermal distortion increases

Engineering Contradiction:

Improvepositioning speedVSAvoidthermal distortion

Core Design Contradiction:

SpeedVSTemperature

Solution Approach 1:

The system applies preliminary anti-action by predicting thermal distortion from voice coil heating before it occurs. The thermal model calculates expected expansion, and the control system preemptively adjusts positioning commands or applies compensatory heating to counteract the anticipated distortion, maintaining positioning accuracy despite high-speed movements.

Inventive Principle:

Principle #9Preliminary anti-action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances temperature stability and reduces misalignment and overlay errors, allowing for more precise and consistent nanoimprint lithography processes by maintaining the same average voice coil power during both idle and active states, thereby improving the reliability and efficiency of the nanoimprint process.

Implementation Method 1

at least one electromagnetic actuator mounted between the movable plate and the mount, wherein an electrical current is applied to the at least one electromagnetic actuator for controlling movement of the moveable plate

Methodology Applied

Scientific EffectElectromagnetic actuation: Electromagnetic Propulsion

Implementation Method 2

changes in imprint head voice coil currents causing Joule heating in the coil

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS11054739B2Imprint apparatus, control method, imprint method and manufacturing method

Publication Date: 2021.07.06 CANON KK

AI summary

An apparatus and method configured to stabilize imprint head temperature. The apparatus and method includes an imprinting apparatus including, a mount attached to a fixed surface, a movable plate movable relative to the mount, at least one electromagnetic actuator mounted between the movable plate and the mount, wherein an electrical current is applied to the at least one electromagnetic actuator for controlling movement of the moveable plate, and wherein a root-mean-square of the electrical current applied to the at least one electromagnetic actuator in an idle state is equal to a root-mean-square of the electrical current applied to the at least one electromagnetic actuator during a continuous imprinting state.