Lithographic Substrate Temperature Conditioning for Overlay Accuracy

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Solution Overview

Problem

Temperature offsets between the substrate and the substrate holder in lithographic apparatuses can lead to substrate distortion and overlay errors during the lithographic process, due to varying temperatures caused by exposure radiation and mechanical components.

Innovation Solution

A lithographic apparatus with a substrate temperature conditioner that actively controls the substrate temperature to match the temperature of the substrate holder before, during, or after transfer, using sensors and heating/cooling systems to maintain thermal alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the substrate holder temperature is increased due to exposure radiation and mechanical components, then the lithographic process can proceed, but substrate distortion and overlay errors occur due to temperature offset between substrate and holder

Engineering Contradiction:

Improvelithographic process throughputVSAvoidsubstrate positioning accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The substrate temperature is adjusted in advance before the substrate is mounted on the substrate holder. This preliminary temperature adjustment ensures that when the substrate is transferred to the holder, minimal temperature offset occurs, preventing substrate distortion and overlay errors while maintaining high productivity

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

A temperature sensor measures the actual temperature of the substrate holder, and this measured temperature is fed back to a controller. The controller then adjusts the substrate temperature accordingly to match the holder temperature, creating a closed-loop control system that maintains thermal alignment and prevents positioning errors

Inventive Principle:

Principle #23Feedback

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 solution prevents substrate distortion and overlay errors by ensuring the substrate and holder are at the same temperature, enhancing the precision and accuracy of the patterning process.

Implementation Method 1

using sensors and heating/cooling systems to maintain thermal alignment

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

using sensors and heating/cooling systems to maintain thermal alignment

Methodology Applied

Scientific EffectCooling: Cooling

Implementation Method 3

The average temperature of the substrate holder can rise, for example by heating caused by incoming exposure radiation during exposure sequences and/or due to heating caused by nearby actuators or motors

Methodology Applied

Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentUS7440076B2Lithographic apparatus, device manufacturing method and device manufactured thereby

Publication Date: 2008.10.21 ASML NETHERLANDS BV

AI summary

A lithographic apparatus arranged to transfer a pattern from a patterning structure onto a substrate is disclosed that includes a substrate holder configured to hold a substrate and a substrate temperature conditioner configured to condition a temperature of the substrate prior to, during, or both, a transfer of the substrate to the substrate holder to substantially match a temperature of the substrate holder.