Reflective Mask Black Border for EUV Edge Reflection Control

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Solution Overview

Problem

The challenge in advanced lithography processes is the reflection of extreme ultraviolet (EUV) light and out-of-band (OoB) light, such as deep ultraviolet (DUV) light, at the edges of patterned fields on a resist film, leading to dose deviation and critical dimension errors, as well as overheating of the reflective mask due to high-energy light absorption.

Innovation Solution

A reflective mask design incorporating a light absorbing layer with anisotropic thermal conductivity, made of materials like graphene or carbon nanotubes, is used at the black border zone to absorb EUV and DUV light, converting it into heat or electricity and dissipating it parallel to the substrate, while the reflective multilayer is removed to minimize reflectivity at this zone.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a reflective mask is used in EUV lithography, then high-resolution patterning is achieved, but light reflection at field edges causes dose deviation and critical dimension errors

Engineering Contradiction:

Improvepatterning precisionVSAvoidlight reflection at field edges

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The patent extracts and removes the reflective multilayer coating from the border zones surrounding the patterned fields. This selective removal eliminates the source of unwanted light reflection at field edges while preserving the reflective coating in the patterned field areas where high-resolution patterning is required, thereby resolving the contradiction between achieving high patterning precision and eliminating edge reflection effects

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent applies different structural properties to different zones of the mask: the patterned fields retain the reflective multilayer coating for high-resolution patterning, while the border zones have the reflective coating removed to prevent light reflection. This local differentiation of structural quality allows the mask to simultaneously achieve high patterning precision in critical areas while eliminating harmful reflections in non-critical border areas

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If the reflective multilayer is removed at the black border zone, then light reflection is minimized, but the mask structure becomes more complex

Engineering Contradiction:

Improvelight reflectionVSAvoidmask structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent segments the mask into distinct functional zones: patterned fields with reflective multilayer coating for high-resolution patterning, and border zones with removed reflective coating to minimize light reflection. This segmentation allows each zone to be optimized for its specific function, achieving reduced light reflection in border areas while maintaining the necessary reflective properties in patterned field areas

Inventive Principle:

Principle #1Segmentation

3Manufacturing precision

If high-energy EUV light is absorbed by the mask, then patterning is achieved, but the mask overheats and distorts

Engineering Contradiction:

ImprovepatterningVSAvoidmask temperature

Core Design Contradiction:

Manufacturing precisionVSTemperature

Solution Approach 1:

The patent extracts and removes the reflective multilayer coating from the border zones, which reduces the overall absorption of high-energy EUV light in areas where patterning is not required. This extraction decreases the heat generation in border regions, preventing mask overheating and distortion while maintaining the necessary light absorption and patterning capability in the patterned field areas

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

This design reduces unwanted light reflection and overheating, improving wafer printing quality by minimizing neighboring die effects and preventing mask distortion.

Implementation Method 1

the light absorbing layer is configured to absorb the extreme ultraviolet (EUV) and deep ultraviolet (DUV) light

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 2

The light absorbing layer has an anisotropic thermal conductivity and is configured to dissipate the heat in a direction substantially parallel to a surface of the reflective mask substrate

Methodology Applied

Scientific EffectThermal conduction with anisotropic properties: Conduction (thermal)

Implementation Method 3

a reflective multilayer over the light absorbing layer

Methodology Applied

Scientific EffectLight reflection: Reflection

Data Source

PatentUS20260044066A1Reflective mask and fabricating method thereof

Publication Date: 2026.02.12 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The prevent disclosure provides a reflective mask. In some embodiments, the reflective mask includes a sp2-hybrid carbon atom-containing layer, a reflective layer, and an absorption pattern. The reflective layer is over the sp2-hybrid carbon atom-containing layer. The absorption pattern is over the reflective layer. In some embodiments, the reflective mask includes a reflective multilayer, a tantalum-containing pattern layer, and a carbon-containing layer. The tantalum-containing pattern layer is over a first surface of the reflective multilayer. The carbon-containing layer is over a second surface of the reflective multilayer opposite to the first surface of the reflective multilayer.