Thin-Film Substrate Holder With Burls for EUV Clamping and Thermal Control

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Solution Overview

Problem

In high-throughput lithographic apparatuses, conventional substrate holders face challenges in securely clamping substrates due to high accelerations, especially in extreme ultraviolet (EUV) radiation lithography where vacuum clamping is not feasible, and temperature control is critical to prevent thermal stress and overlay errors.

Innovation Solution

A substrate holder with a thin-film stack forming electronic or electric components, including burls for substrate support, integrated with real-time temperature measurement and heating systems, allowing for electrostatic clamping and improved temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vacuum clamping is used to secure substrates, then clamping reliability is improved, but it cannot be applied in EUV lithography where vacuum environment is required

Engineering Contradiction:

Improveclamping reliabilityVSAvoidapplicability in EUV lithography

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent replaces the mechanical vacuum clamping system with an electrostatic clamping system. The substrate holder includes an electrostatic clamping device that uses electrostatic forces to secure the substrate, eliminating the need for vacuum conditions. This allows the same clamping function to be performed in both conventional lithography and EUV lithography environments where vacuum is required.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Device complexity

If conventional substrate holders are used, then device simplicity is maintained, but temperature control precision is insufficient leading to thermal stress and overlay errors

Engineering Contradiction:

Improveholder structure simplicityVSAvoidoverlay precision

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent merges the substrate holder with integrated temperature control systems including heating elements and temperature sensors directly embedded in the holder structure. This combination allows precise temperature management to maintain substrate flatness and prevent thermal stress, thereby improving overlay precision without requiring separate external temperature control equipment.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The substrate holder incorporates real-time temperature sensing capabilities that provide feedback to the control system. This enables dynamic adjustment of heating elements to maintain precise temperature control, compensating for thermal variations during the lithography process and preventing overlay errors caused by thermal expansion or contraction.

Inventive Principle:

Principle #23Feedback

3Ease of manufacture

If simple burl structures are used for substrate support, then ease of manufacture is improved, but clamping force is insufficient under high acceleration conditions

Engineering Contradiction:

Improveholder manufacturing simplicityVSAvoidclamping force

Core Design Contradiction:

Ease of manufactureVSForce

Solution Approach 1:

The patent implements an electrostatic clamping mechanism that dynamically generates sufficient clamping force to counteract high acceleration forces during lithography. The electrostatic actuation system can rapidly adjust and maintain appropriate clamping pressure on the substrate, ensuring it remains securely positioned even under the extreme acceleration conditions of high-throughput lithographic apparatuses.

Inventive Principle:

Principle #15Dynamics

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

The substrate holder effectively secures substrates during high accelerations and maintains precise temperature control, reducing thermal stress and overlay errors in lithographic processes.

Implementation Method 1

a thin-film stack provided on the surface and forming an electronic or electric component

Methodology Applied

Scientific EffectThin film deposition: Deposition (physical)

Implementation Method 2

a plurality of burls provided on the thin-film stack and having end surfaces to support a substrate

Methodology Applied

Scientific EffectMechanical support: Mechanical Force

Implementation Method 3

integrated with real-time temperature measurement and heating systems, allowing for electrostatic clamping and improved temperature control

Methodology Applied

Scientific EffectThermal control: Heating

Implementation Method 4

allowing for electrostatic clamping

Methodology Applied

Scientific EffectElectrostatic force: Electrostatics

Data Source

PatentUS11235388B2Substrate holder, lithographic apparatus, device manufacturing method, and method of manufacturing a substrate holder

Publication Date: 2022.02.01 ASML NETHERLANDS BV

AI summary

A substrate holder for a lithographic apparatus has a main body having a thin-film stack provided on a surface thereof. The thin-film stack forms an electronic or electric component such as an electrode, a sensor, a heater, a transistor or a logic device, and has a top isolation layer. A plurality of burls to support a substrate are formed on the thin-film stack or in apertures of the thin-film stack.