EUV Mask Cleaning Module Vacuum Integration

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Solution Overview

Problem

Existing methods for cleaning extreme ultraviolet (EUV) masks are ineffective in removing thin carbon buildup before exposure, leading to adverse effects on the first few semiconductor wafers, and the masks become contaminated when transferred from a cleaning module to atmospheric environments.

Innovation Solution

Integration of a cleaning module within the lithography tool, allowing for the removal of carbon buildup under vacuum conditions before transferring the mask to the exposure module, utilizing methods such as hydrogen radicals, hydrogen plasma, ultrasonic waves, laser decomposition, ultraviolet ozone, or electron-stimulated desorption to maintain the mask's cleanliness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the mask is cleaned using external cleaning methods before insertion into the lithography tool, then the carbon buildup can be removed, but the mask becomes contaminated again during transfer to atmospheric environment

Engineering Contradiction:

Improvemask cleanlinessVSAvoidcarbon buildup

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cleaning module is integrated within the lithography tool, merging the cleaning function with the exposure system. This allows the mask to be cleaned inside the vacuum environment of the lithography tool, eliminating the need to transfer the mask through atmospheric conditions that cause contamination. The cleaning module includes a cleaning head with hydrogen plasma generation capability that can clean the mask surface while the mask remains in the vacuum chamber.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The cleaning operation is performed in the vacuum environment inside the lithography tool, which serves as an inert atmosphere preventing oxidation and contamination of the mask surface. By conducting the cleaning process in this controlled vacuum environment rather than in atmospheric conditions, the mask maintains its cleanliness without being exposed to contaminants during transfer.

Inventive Principle:

Principle #39Inert atmosphere (Inert environment)

2Ease of manufacture

If the mask is transferred between cleaning module and lithography tool in atmospheric environment, then the cleaning process can be performed, but the mask gets recontaminated with carbon particles

Engineering Contradiction:

Improvecleaning accessibilityVSAvoidpattern transfer quality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If conventional cleaning methods are used on EUV masks, then general cleaning can be achieved, but thin carbon buildup before exposure cannot be effectively removed

Engineering Contradiction:

Improvecleaning process simplicityVSAvoidfirst wafer quality

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent replaces conventional mechanical cleaning methods with hydrogen plasma cleaning. The cleaning head generates hydrogen plasma that chemically reacts with and removes carbon buildup from the mask surface. This substitution of mechanical cleaning with plasma-based chemical cleaning enables effective removal of thin carbon layers that conventional methods cannot remove, while maintaining a simple automated operation process.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

Ensures the first wafers are not adversely affected by carbon buildup and maintains the mask's cleanliness throughout the lithography process by effectively removing carbon deposits before exposure, preventing contamination and ensuring consistent pattern transfer.

Implementation Method 1

utilizing methods such as hydrogen radicals, hydrogen plasma

Methodology Applied

Scientific EffectHydrogen radicals: Plasma

Implementation Method 2

utilizing methods such as hydrogen radicals, hydrogen plasma

Methodology Applied

Scientific EffectHydrogen plasma: Plasma

Implementation Method 3

utilizing methods such as hydrogen radicals, hydrogen plasma, ultrasonic waves

Methodology Applied

Scientific EffectUltrasonic waves: Ultrasonic Vibration

Implementation Method 4

utilizing methods such as hydrogen radicals, hydrogen plasma, ultrasonic waves, laser decomposition

Methodology Applied

Scientific EffectLaser decomposition: Laser Ablation

Implementation Method 5

utilizing methods such as hydrogen radicals, hydrogen plasma, ultrasonic waves, laser decomposition, ultraviolet ozone

Methodology Applied

Scientific EffectUltraviolet ozone: Photo-oxidation

Implementation Method 6

utilizing methods such as hydrogen radicals, hydrogen plasma, ultrasonic waves, laser decomposition, ultraviolet ozone, or electron-stimulated desorption

Methodology Applied

Scientific EffectElectron-stimulated desorption: Electron Impact Desorption

Data Source

PatentUS11921434B2Mask cleaning

Publication Date: 2024.03.05 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An apparatus includes a vacuum chamber, a reflective optical element arranged in the vacuum chamber and configured to reflect an extreme ultra-violet (EUV) light, and a cleaning module positioned in the vacuum chamber. the cleaning module is operable to provide a mitigation gas flowing towards the reflective optical element and provide a hydrogen-containing gas flowing towards the reflective optical element. The mitigation gas mitigates, by chemical reaction, contamination of the reflective optical element.