Lithographic Encoder Target Recess and Thermal Management

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Solution Overview

Problem

The increasing demands for accuracy and stability in lithographic apparatuses, particularly due to larger substrate handling and thermal expansion issues, compromise the positioning accuracy of encoder type sensor systems used in lithographic processes.

Innovation Solution

Incorporating a recess to accommodate the encoder sensor target, providing a gas stream to stabilize temperature, using a heat shielding layer, and employing materials with zero thermal expansion or high thermal conductivity to minimize temperature effects on measurement accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the encoder sensor target size is increased to handle larger substrates and provide increased substrate handling flexibility, then substrate handling capability is improved, but thermal expansion effects and positioning accuracy deteriorate

Engineering Contradiction:

Improvesubstrate handling flexibilityVSAvoidposition measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent changes the material parameter of the encoder sensor target by using materials with zero or low thermal expansion coefficients. This allows the target to maintain dimensional stability and measurement precision even when the target size is increased for larger substrate handling capability.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures for the encoder sensor target, combining materials with complementary properties including zero thermal expansion, high thermal conductivity, and high stiffness. This composite approach enables large target sizes for versatile substrate handling while maintaining nanometer-level positioning accuracy through superior thermal and mechanical stability.

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If common encoder sensor target materials are used, then ease of manufacture is improved, but temperature stability must be controlled within milli Kelvins to achieve one nanometer stability

Engineering Contradiction:

Improvemanufacturing easeVSAvoidtemperature stability

Core Design Contradiction:

Ease of manufactureVSTemperature

Solution Approach 1:

The patent fundamentally changes the thermal parameter of the encoder sensor target material by selecting materials with zero or low thermal expansion coefficients and high thermal conductivity. This parameter change eliminates the need for extreme temperature control (milli Kelvin stability), making the system both easier to manufacture and more stable thermally.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent directly addresses thermal expansion effects by using materials specifically selected for their zero or low thermal expansion properties. This eliminates the harmful thermal expansion that would otherwise require extreme temperature control, thereby improving both manufacturing ease and temperature stability.

Inventive Principle:

Principle #37Thermal expansion

3Adaptability or versatility

If the range of movement of the substrate table is increased to provide increased flexibility in substrate handling, then substrate handling flexibility is improved, but the size of the encoder sensor target must be increased which aggravates thermal effects

Engineering Contradiction:

Improvesubstrate handling flexibilityVSAvoidthermal effects

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent changes the thermal parameters of the encoder sensor target material (zero thermal expansion coefficient, high thermal conductivity) to enable large target sizes required for increased substrate table movement range without suffering from aggravated thermal effects.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials with optimized thermal and mechanical properties to construct large encoder sensor targets that can accommodate increased substrate table movement ranges while resisting thermal deformation and maintaining measurement accuracy.

Inventive Principle:

Principle #40Composite materials

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

These measures enhance the stability and accuracy of position measurements, allowing for increased substrate handling flexibility and maintaining high precision in nanometer-scale stability.

Implementation Method 1

providing a gas stream to stabilize temperature

Methodology Applied

Scientific EffectConvection: Convection

Implementation Method 2

using a heat shielding layer

Methodology Applied

Scientific EffectThermal Insulation: Thermal Insulation

Implementation Method 3

employing materials with zero thermal expansion or high thermal conductivity

Methodology Applied

Scientific EffectZero Thermal Expansion: Zero Thermal Expansion

Implementation Method 4

employing materials with zero thermal expansion or high thermal conductivity

Methodology Applied

Scientific EffectThermal Conduction: Conduction (thermal)

Data Source

PatentUS8836913B2Lithographic apparatus having an encoder type position sensor system

Publication Date: 2014.09.16 ASML NETHERLANDS BV

AI summary

A lithographic apparatus is disclosed that includes an encoder type sensor system configured to measure a position of a substrate table of the lithographic apparatus relative to a reference structure. The encoder type sensor system includes an encoder sensor head and an encoder sensor target and the lithographic apparatus comprises a recess to accommodate the encoder sensor target.