Electro-Optical EUV Mirror Layer for Aberration Compensation

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Solution Overview

Problem

Optical aberrations in EUV radiation sources cause non-uniformity in critical dimension (CD) and pattern placement error (PPE) during lithographic processes, leading to image degradation and pattern defects on wafers.

Innovation Solution

Employing an electro optical layer in mirrors of the exposure device that alters refractive index in response to applied electric fields, using the Pockels or Kerr effect to compensate for optical aberrations by adjusting the phase and amplitude of EUV radiation, thereby minimizing aberrations and improving CD uniformity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional mirrors are used in the exposure device, then the device complexity is low, but optical aberrations cause non-uniformity in critical dimension and pattern placement error

Engineering Contradiction:

Improvecritical dimension uniformityVSAvoidexposure device structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies parameter changes by modifying the refractive index of the electro-optical layer through applied electric fields. The controller adjusts voltage parameters to the electro-optical layer, causing changes in refractive index that compensate for optical aberrations in the mirrors, thereby improving critical dimension uniformity without requiring complete redesign of the mirror system.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The electro-optical layer serves as an intermediary element between the mirrors and the EUV radiation path. This layer mediates the optical aberrations by introducing controllable refractive index variations that counteract the mirror-induced aberrations, allowing correction without directly modifying the mirror surfaces or structures.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If electro-optical layer is added to mirrors, then optical aberrations are reduced and CD uniformity improves, but device complexity increases

Engineering Contradiction:

Improvepattern placement accuracyVSAvoidmirror structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent uses parameter changes by applying variable electric fields to the electro-optical layer, dynamically adjusting its refractive index to compensate for pattern placement errors. The controller modifies voltage parameters in real-time during lithographic operations, enabling precise correction of optical aberrations without physical modification of the mirror geometry.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces mechanical adjustments of mirror surfaces with an electro-optical control system. Instead of mechanically adjusting mirror positions or shapes to correct aberrations, the system uses electric fields to modulate the refractive index of the electro-optical layer, providing a non-mechanical method for achieving precise pattern placement accuracy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Manufacturing precision

If multiple voltages are applied to electro-optical layer, then phase and amplitude of EUV radiation are adjusted to compensate aberrations, but energy consumption increases

Engineering Contradiction:

Improveoptical aberration compensationVSAvoidvoltage application energy

Core Design Contradiction:

Manufacturing precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies local quality by distributing multiple voltage applications to different regions of the electro-optical layer. Each region receives tailored voltage levels to create specific refractive index variations where needed, rather than uniformly increasing energy across the entire layer. This localized approach compensates for spatially varying optical aberrations while minimizing overall energy consumption.

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

The solution effectively reduces optical aberrations, enhancing CD uniformity and reducing PPE, resulting in improved pattern accuracy and quality on wafers.

Implementation Method 1

using the Pockels or Kerr effect to compensate for optical aberrations by adjusting the phase and amplitude of EUV radiation

Methodology Applied

Scientific EffectPockels effect: Pockels Effect

Implementation Method 2

using the Pockels or Kerr effect to compensate for optical aberrations by adjusting the phase and amplitude of EUV radiation

Methodology Applied

Scientific EffectKerr effect: Kerr Effect

Data Source

PatentUS20250271770A1Method and device for generating EUV radiation

Publication Date: 2025.08.28 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A mirror structure includes an insulator layer and a first conductive layer disposed on the insulator layer. The first conductive layer includes a first non-conductive film disposed on the insulator layer. The first non-conductive film includes one or more first conductive segments. The mirror structure also includes a reflective layer disposed on the first conductive layer and an electro optical layer disposed on the reflective layer. The mirror structure further includes a second conductive layer disposed on the electro optical layer. The second conductive layer includes a second non-conductive film disposed on the electro optical layer. The second non-conductive film includes one or more second conductive segments.