EUV Mask Pellicle Frame Mounting to Shield Adhesives

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Solution Overview

Problem

In EUV lithography, mask 3D effects and shadowing issues arise due to thick absorber layers, leading to feature-size dependent focus and pattern placement shifts, reducing contrast and quality of photoresist patterns, especially as feature sizes shrink.

Innovation Solution

A pellicle membrane frame is attached directly to the substrate of a photolithography mask, positioned in a trench formed in the reflective multilayer stack and absorber layer, reducing exposure of adhesives to detrimental radiation and enhancing the mask's lifetime.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a thick absorber layer is used in EUV masks, then absorption of incident radiation is improved, but mask 3D effects and shadowing issues arise leading to focus and pattern placement shifts

Engineering Contradiction:

Improveradiation absorptionVSAvoidpattern placement accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The mask structure is segmented into functional zones: the absorber layer is patterned with openings to create transparent regions, allowing EUV radiation to pass through to the substrate. This segmentation enables the mask to simultaneously absorb radiation in patterned areas while maintaining transparency in unpatterned areas, resolving the contradiction between absorption and precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A pellicle membrane is introduced as an intermediary protective layer between the absorber layer and the substrate. This membrane prevents direct contact and contamination while allowing radiation to pass through, mediating between the absorber layer's protective function and the substrate's requirement for precise pattern transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If adhesives are used to attach the pellicle frame, then structural support is improved, but adhesive degradation occurs due to exposure to EUV radiation and thermal effects

Engineering Contradiction:

Improvestructural supportVSAvoidadhesive durability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The pellicle membrane serves as a protective intermediary barrier between the adhesives and the harsh EUV radiation environment. This membrane allows structural support to be maintained while shielding the adhesives from direct radiation exposure, preventing degradation and extending the mask's operational lifetime.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The pellicle membrane, initially introduced as a protective barrier, inadvertently creates a radiation shadowing effect that protects the adhesives from EUV exposure. This protective function converts the potential harm of radiation exposure into a beneficial shielding effect, preserving adhesive integrity.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If the pellicle frame is positioned in a trench formed in the reflective multilayer stack and absorber layer, then adhesive exposure to radiation is reduced, but structural complexity increases

Engineering Contradiction:

Improveadhesive protectionVSAvoidmask structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The pellicle frame is nested within a trench that is itself formed within the reflective multilayer stack and absorber layer structure. This nested configuration provides protective shielding for the adhesives while integrating the pellicle system into the existing mask architecture, minimizing additional structural complexity.

Inventive Principle:

Principle #7Nested doll (Nesting)

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 configuration minimizes adhesive degradation, maintaining the mask's integrity and improving pattern transfer fidelity by shielding adhesives from EUV radiation and thermal effects, thus enhancing the lithography process yield.

Implementation Method 1

positioned in a trench formed in the reflective multilayer stack and absorber layer, reducing exposure of adhesives to detrimental radiation

Methodology Applied

Scientific EffectRadiation shielding: Absorption (EM radiation)

Implementation Method 2

shielding adhesives from EUV radiation and thermal effects

Methodology Applied

Scientific EffectThermal shielding: Thermal Insulation

Implementation Method 3

absorbing a portion of the incident radiation in the patterned absorber layer and blocking, by one or more of the patterned absorber layer or the reflective multilayer stack, a portion of the incident radiation from the pellicle frame adhesive layer

Methodology Applied

Scientific EffectRadiation absorption: Absorption (EM radiation)

Data Source

PatentUS20250355342A1Pellicle assembly mounting for lithography mask

Publication Date: 2025.11.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

An extreme ultraviolet mask including a substrate, a reflective multilayer stack on the substrate and patterned absorber layer on the reflective multilayer stack is provided with a pellicle membrane frame attached to the substrate. In some embodiments, the pellicle membrane frame is attached to the substrate using an adhesive between the pellicle membrane frame and the substrate. In some embodiments, the pellicle membrane frame is located in a trench formed in the reflective multilayer stack and patterned absorber layer. In other embodiments, the pellicle membrane frame not located in a trench formed in the reflective multilayer stack and patterned absorber layer.