EUV Reticle Static Charge Neutralization via Ionizer

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Solution Overview

Problem

Advanced lithography processes face challenges in maintaining the cleanliness and defect-free nature of extreme ultraviolet (EUV) masks due to static charge accumulation, which can lead to electrostatic discharge damage and particulate contamination, affecting the quality of the projected pattern.

Innovation Solution

A reticle container with a discharging device, such as an alpha-ionizer, is used to neutralize static charges on the EUV reticle by emitting alpha particles that ionize air molecules, attracting and neutralizing static charges, and a conductive material structure on the reticle directs these charges to the reticle electrostatic-clamp, preventing damage and contamination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a reflective mask is used in EUV lithography, then the manufacturing precision is improved, but the reliability deteriorates due to static charge accumulation causing electrostatic discharge damage

Engineering Contradiction:

Improvepattern qualityVSAvoidmask cleanliness

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent converts the harmful static charge accumulation into a beneficial effect by using an ionizer to generate ions that neutralize the static charges. The ionizer emits ions that are attracted to the negatively charged mask, converting the harmful electrostatic potential into a controlled ion-neutralization process that prevents discharge damage while maintaining mask cleanliness and pattern quality

Inventive Principle:

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

Solution Approach 2:

The ionizer acts as an intermediary device between the static-charged mask and the environment. It introduces ions as a mediating substance that facilitates charge neutralization without direct contact between the mask and potential discharge sources, thereby protecting the mask while maintaining the precision of the lithography process

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If static charges are not neutralized, then the device complexity is reduced, but the object-affected harmful factors increase due to electrostatic discharge damage and particulate contamination

Engineering Contradiction:

Improvesystem simplicityVSAvoidelectrostatic discharge damage

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The ionizer performs preliminary action by continuously or periodically neutralizing static charges on the mask before they can accumulate to dangerous levels. This preventive measure eliminates the need for complex emergency discharge systems, reducing overall device complexity while effectively preventing electrostatic discharge damage and particulate contamination

Inventive Principle:

Principle #10Preliminary 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

The solution effectively neutralizes static charges on the EUV reticle, preventing electrostatic discharge damage and particulate contamination, thereby maintaining the cleanliness and quality of the projected pattern during lithography processes.

Implementation Method 1

emitting alpha particles that ionize air molecules, attracting and neutralizing static charges

Methodology Applied

Scientific EffectIonization: Ionisation

Data Source

PatentUS11982944B2Method of lithography process and transferring a reticle

Publication Date: 2024.05.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of lithography process is provided. The method includes forming a conductive layer over a reticle. The method includes applying ionized particles to the reticle by a discharging device. The method includes forming a photoresist layer over a semiconductor substrate. The method includes securing the semiconductor substrate by a wafer electrostatic-clamp. The method also includes patterning the photoresist layer by emitting radiation from a radiation source via the reticle.