EUV Mask Phase Defect Repair via Localized Absorber Deposition

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Solution Overview

Problem

Extreme ultraviolet lithography (EUVL) masks suffer from phase defects due to microscopic non-flatness, which cause severe pattern distortion on wafers, necessitating an efficient method to mitigate these defects and improve print fidelity.

Innovation Solution

A method involving the determination of phase-defect location and size using tools like atomic force microscopy, followed by local deposition of an absorber material to cover the defect region and removal of a portion of the absorption layer to form an absorber-absent region, thereby reducing the phase shift impact.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a multi-layer structure is used in an EUVL mask to achieve high resolution patterning, then the lithography capability is improved, but microscopic non-flatness on the substrate surface causes phase defects that deteriorate print fidelity

Engineering Contradiction:

Improvelithography resolutionVSAvoidprint fidelity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent performs preliminary identification of phase defect locations and sizes using atomic force microscopy or aerial image metrology before the lithography process. By detecting and mapping defects in advance, the system can pre-compensate for their effects through adjusted exposure parameters or targeted repair actions, preventing print fidelity deterioration while maintaining high resolution patterning capability

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements a feedback mechanism where aerial image metrology measurements are used to identify phase defects, and this information feeds back to adjust the lithography process parameters or trigger repair operations. The feedback loop continuously monitors and corrects for defect-induced phase errors, maintaining print fidelity despite the presence of substrate non-flatness in the multi-layer mask structure

Inventive Principle:

Principle #23Feedback

2Measurement precision

If atomic force microscopy is used to determine phase defect location and size, then measurement precision is improved, but the complexity of the repair process increases

Engineering Contradiction:

Improvedefect location and size determinationVSAvoidrepair process complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical repair operations with a streamlined process that uses atomic force microscopy for precise defect characterization, then applies computational methods to determine repair parameters. The high measurement precision from AFM is leveraged to simplify subsequent repair steps by providing exact defect coordinates and dimensions, reducing the need for trial-and-error or complex manual adjustment procedures

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If absorber material is deposited to cover phase defect regions, then print fidelity is improved, but the manufacturing complexity and process time increase

Engineering Contradiction:

Improveprint fidelityVSAvoidmask fabrication efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies absorber material deposition only in specific local regions where phase defects are detected, rather than uniformly across the entire mask surface. This localized approach, guided by precise defect mapping from atomic force microscopy, restores print fidelity in affected areas while minimizing additional process steps and material usage, thereby maintaining higher fabrication efficiency compared to full-mask repair methods

Inventive Principle:

Principle #3Local quality

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 approach effectively reduces the impact of phase defects, enhancing the printability and fidelity of EUVL patterns by minimizing phase errors, even when defects introduce significant phase shifts, and is applicable to various EUV mask types.

Implementation Method 1

determining the location and size of the phase-defect region by a topography measured by an atomic force microscopy tool

Methodology Applied

Scientific EffectAtomic force microscopy: Scanning Probe Microscopy

Implementation Method 2

depositing an absorber material to cover the phase-defect region

Methodology Applied

Scientific EffectPhysical vapor deposition: Physical Vapour Deposition

Implementation Method 3

removing a portion of the patterned absorption layer near the phase-defect region in the patterned EUV mask to form an absorber-absent region

Methodology Applied

Scientific EffectFocused ion beam etching: Ion Beam

Data Source

PatentUS8785084B2Method for mask fabrication and repair

Publication Date: 2014.07.22 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for repairing phase defects for an extreme ultraviolet (EUV) mask is disclosed. The method includes receiving a patterned EUV mask with at least one phase-defect region, determining location and size of the phase-defect region, depositing an absorber material to cover the phase-defect region and removing a portion of the patterned absorption layer near the phase-defect region in the patterned EUV mask to form an absorber-absent region.