Reticle Cleaning via Ozone and UV Decomposition

Solution Overview

Problem

During integrated circuit (IC) manufacturing, reticles stored in vacuum libraries accumulate particles and hydrocarbon contamination, leading to reduced reflectivity and critical dimension (CD) uniformity issues when used in lithographic processes, as existing cleaning methods with solvents can introduce additional particles and delay the process without effectively addressing the oxide layer deposition and modified top layer composition.

Innovation Solution

A treatment device using ozone fluid and UV radiation is employed to decompose particles and hydrocarbon contamination on reticles, remedying the deposited oxide and modified top layer composition without damaging the reticle structure, thereby enhancing CD uniformity and reducing the risk of introducing additional particles into the lithographic system.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solvents are used to clean reticles, then particles are removed, but additional particles are introduced and process time is delayed

Engineering Contradiction:

Improvereticle cleanlinessVSAvoidprocess time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent replaces mechanical/chemical cleaning methods (solvent-based cleaning) with a light-based treatment system. A light source irradiates the reticle surface to decompose organic contamination and restore reflectivity without requiring physical contact or chemical solvents, thereby eliminating the risk of introducing additional particles and reducing process time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical-chemical state of the reticle surface through controlled light irradiation. The light energy modifies the molecular structure of organic contaminants on the reticle surface, transforming them into volatile compounds that can be removed without solvents, thus improving cleanliness while avoiding particle introduction and time delays.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If solvents are used to clean reticles, then particles are removed, but additional particles are introduced

Engineering Contradiction:

Improvereticle cleanlinessVSAvoidparticle contamination

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical/chemical cleaning methods (solvent-based cleaning) with a light-based treatment system. A light source irradiates the reticle surface to decompose organic contamination and restore reflectivity without requiring physical contact or chemical solvents, thereby eliminating the risk of introducing additional particles and reducing process time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces light as an intermediary substance between the cleaning mechanism and the reticle surface. Instead of using solvents that may leave residues or introduce particles, light acts as a clean intermediary that transfers energy to decompose contaminants without material transfer, thus preventing particle contamination.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If reticles are stored in vacuum libraries, then contamination is prevented, but oxide layers deposit and reflectivity decreases

Engineering Contradiction:

Improvereticle protectionVSAvoidreflectivity

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary treatment to the reticle surface by irradiating it with light before the reticle is used in lithography. This pre-treatment decomposes organic contaminants and restores the original composition of the top layers, including the reflective coating, thereby recovering reflectivity while maintaining the protective vacuum storage condition.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the physical-chemical state of the reticle surface through controlled light irradiation. The light energy modifies the molecular structure of organic contaminants on the reticle surface, transforming them into volatile compounds that can be removed without solvents, thus improving cleanliness while avoiding particle introduction and time delays.

Inventive Principle:

Principle #35Parameter changes

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 ozone fluid and UV radiation treatment effectively improves reticle reflectivity and CD uniformity, reducing the exposure time and costs associated with the lithography process while maintaining the integrity of the reticle structure, thus optimizing the lithographic process efficiency.

Implementation Method 1

A surface of the reticle is treated by releasing ozone fluid over the surface of the reticle and irradiating the surface of the reticle with UV radiation of a UV source for a predetermined irradiation time

Methodology Applied

Scientific EffectPhotodissociation: Photodissociation

Implementation Method 2

A surface of the reticle is treated by releasing ozone fluid over the surface of the reticle and irradiating the surface of the reticle with UV radiation of a UV source for a predetermined irradiation time

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS20240393701A1Enhancing lithography operation for manufacturing semiconductor devices

Publication Date: 2024.11.28 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of cleaning a reticle includes applying ozone fluid over a surface of the reticle, and while the ozone fluid is over the surface of the reticle, irradiating the surface of the reticle with ultraviolet (UV) radiation for an irradiation time to treat the surface of the reticle. The method of cleaning the reticle further includes adjusting the irradiation time based on a reflected UV beam from the surface of the reticle.