Photomask Cleaning Apparatus with Segmented Region Protection

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Solution Overview

Problem

Conventional photomask cleaning methods often result in ineffective pattern transcription due to foreign substances, leading to haze and critical dimension skew, and can damage the photomask by directly exposing it to cleaning liquids, reducing its lifetime.

Innovation Solution

A method and apparatus that protect the pattern on a first region of the photomask by spraying a cleaning liquid from the inner region of a second region towards its outer region and simultaneously blowing gas from the first region towards the second region, using a guide nozzle and frame to direct the cleaning liquid away from the pattern, with options for sulfuric acid solution and clean dry air or nitrogen gas.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cleaning liquid is sprayed directly on the photomask to remove contaminants, then cleaning effectiveness is improved, but the pattern on the photomask is damaged and critical dimension changes occur

Engineering Contradiction:

Improvecleaning effectivenessVSAvoidcritical dimension

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The photomask surface is divided into two distinct regions: a first region containing the pattern to be protected, and a second region surrounding it where contaminants are removed. This segmentation allows selective cleaning of the second region while preserving the pattern integrity in the first region, resolving the contradiction between cleaning effectiveness and pattern protection.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different treatment approaches are applied to different regions of the photomask. The second region receives cleaning liquid spray for contaminant removal, while the first region is protected from direct liquid contact. This local differentiation enables effective cleaning without damaging the critical pattern areas, simultaneously achieving both cleaning effectiveness and manufacturing precision.

Inventive Principle:

Principle #3Local quality

2Reliability

If cleaning liquid is used to remove remnant adhesives and contaminants, then photomask cleanliness is improved, but photomask lifetime is reduced due to damage

Engineering Contradiction:

Improvephotomask cleanlinessVSAvoidphotomask lifetime

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

By segmenting the photomask into a pattern region (first region) and a cleaning region (second region), the cleaning liquid is directed only to the second region where contaminants and remnant adhesives exist. This prevents direct contact between the cleaning liquid and the sensitive pattern structures, thereby maintaining photomask cleanliness while preserving its lifetime through reduced chemical exposure and physical damage.

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If gas is blown from the first region toward the second region during cleaning, then pattern protection is improved, but cleaning liquid distribution may be affected

Engineering Contradiction:

Improvepattern integrityVSAvoidcleaning process control

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

A gas flow is introduced as an intermediary element between the cleaning liquid and the pattern region. The gas is blown from the first region toward the second region, creating a protective barrier that prevents cleaning liquid from reaching the pattern while allowing the cleaning process to proceed effectively in the second region. This intermediary gas flow resolves the contradiction by protecting pattern integrity without significantly complicating the overall cleaning process control.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Effectively removes contaminants from the photomask without exposing the pattern to the cleaning liquid, preventing changes in critical dimension or optical density and minimizing photomask damage, thus maintaining its integrity and extending its lifespan.

Implementation Method 1

Spraying a cleaning liquid from an inner region of the second region toward an outer region of the second region to remove material from the second region

Methodology Applied

Scientific EffectChemical dissolution:

Implementation Method 2

spraying deionized water from the inner region of the second region toward the outer region of the second region to remove the cleaning liquid

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentUS9122177B2Apparatus for cleaning photomask

Publication Date: 2015.09.01 LONGITUDE FLASH MEMORY SOLUTIONS LTD

AI summary

Provided is a method and apparatus for cleaning a photomask. The photomask including a first region and a second region surrounding the first region, a pattern to be protected disposed on the first region, and a material to be removed exists on the second region. A cleaning liquid is sprayed from an inside region of the second region toward an outer region of the second region to remove the material, and a gas is blown from the first region toward the second region to protect the pattern.