Photosensitive Edge Bead Removal via Rough Profile

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Solution Overview

Problem

Conventional methods for removing photosensitive material from the outer edge of a substrate in lithographic apparatuses often result in defects such as watermarks due to the meniscus pinning effect, leading to reduced yield and increased errors.

Innovation Solution

A method and apparatus that control the removal of photosensitive material to generate a radial width edge with a varying thickness profile, creating a rough or patterned edge to alter the pinning mechanism and reduce water loss, using techniques like oscillating nozzles, lasers, or plasma jets to modulate the edge profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional edge bead removal is performed using a nozzle, then photosensitive material is removed from the substrate edge, but the meniscus pinning effect causes droplets to form on the substrate surface

Engineering Contradiction:

Improveedge bead removal qualityVSAvoiddroplet formation

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent changes the geometric parameters of the edge profile by creating a rough or patterned edge structure with varying thickness instead of a uniform sharp edge. This modifies the meniscus behavior and eliminates droplet formation while maintaining effective edge bead removal

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces asymmetry in the edge profile by creating a rough or patterned structure with varying thickness across the edge. This asymmetric profile disrupts the symmetric meniscus pinning effect that causes droplet formation, thereby solving the contradiction

Inventive Principle:

Principle #4Asymmetry

2Productivity

If a uniform sharp edge is created around the photosensitive material layer, then edge bead removal is effective, but water loss and film pulling occur due to meniscus pinning

Engineering Contradiction:

Improveedge bead removal efficiencyVSAvoidwater loss

Core Design Contradiction:

ProductivityVSLoss of substance

Solution Approach 1:

The patent modifies the geometric parameters of the edge by creating a rough or patterned profile with varying thickness. This changes the meniscus interaction characteristics, preventing water loss and film pulling while maintaining productivity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary action by creating the rough or patterned edge profile before the substrate enters the immersion lithographic apparatus. This pre-modification prevents subsequent water loss and film pulling issues during processing

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If spin coating is used to apply photosensitive material, then uniform coverage is achieved, but a thick ring forms at the substrate edge

Engineering Contradiction:

Improvephotosensitive material uniformityVSAvoidedge bead thickness

Core Design Contradiction:

Manufacturing precisionVSShape

Solution Approach 1:

The patent extracts or removes the problematic thick edge bead that forms during spin coating. By selectively removing material from the edge region and creating a rough or patterned profile, the unwanted thick ring is eliminated while preserving the uniform central area

Inventive Principle:

Principle #2Taking out (Extraction)

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 controlled edge profile reduces the formation of droplets and defects on the substrate surface, enhancing the yield and reducing errors by minimizing water loss and film pulling issues.

Implementation Method 1

using techniques like oscillating nozzles, lasers, or plasma jets to modulate the edge profile

Methodology Applied

Scientific EffectMechanical oscillation: Vibration

Implementation Method 2

using techniques like oscillating nozzles, lasers, or plasma jets to modulate the edge profile

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 3

using techniques like oscillating nozzles, lasers, or plasma jets to modulate the edge profile

Methodology Applied

Scientific EffectPlasma erosion: Plasma

Implementation Method 4

any variation or irregularity on the surface of the substrate may act as a meniscus pinning feature. In particular, the surface of the substrate and/or the edge of the photosensitive material remaining on the surface of the substrate after conventional edge bead removal process may act a meniscus pinning feature

Methodology Applied

Scientific EffectMeniscus pinning: Capillary Action

Data Source

PatentUS10948825B2Method for removing photosensitive material on a substrate

Publication Date: 2021.03.16 ASML NETHERLANDS BV

AI summary

A method of processing a substrate includes: providing a substrate with a layer of photosensitive material on a surface of the substrate; and removing at least part of the photosensitive material from around an outer edge of the layer of photosensitive material so as to generate an edge, having a radial width, around the layer of photosensitive material remaining on the surface of the substrate, wherein the photosensitive material varies in thickness forming a thickness profile across the radial width and the removing is controlled so as to generate variation in the thickness profile along the length of the edge, and/or wherein the removing is controlled so as to generate a rough edge around the layer of photosensitive material remaining on the surface of the substrate.