Invisible Pellicle Lithography Mask Protection

Solution Overview

Problem

Existing EUV lithography systems face challenges in protecting reflective masks from contaminant particles, which can lead to defects in semiconductor integrated circuits due to the high absorption of EUV light by all materials, necessitating the use of reflective optics and a protective pellicle to prevent particle contamination.

Innovation Solution

The implementation of an optical module that generates an invisible pellicle using laser beams or light sources to trap and remove contaminant particles through radiation pressure, preventing them from reaching the mask surface during the lithography process, thereby avoiding aberrations and defects in the ICs produced.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a solid pellicle is used to protect the mask from contaminant particles, then the mask is protected from damage and contamination, but critical dimension errors increase and exposure radiation energy consumption increases

Engineering Contradiction:

Improvemask protection from contaminant particlesVSAvoidcritical dimension errors

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent replaces the mechanical solid pellicle system with an optical field-based particle manipulation system. Laser beams create optical forces (radiation pressure and gradient forces) to trap and remove particles without physical contact, eliminating the mechanical pellicle structure that caused CD errors and energy loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces laser beams as an intermediary between the contaminant particles and the mask. The optical field serves as a mediator that exerts forces on particles to trap and remove them, without requiring a solid pellicle to be placed between the particles and mask.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a solid pellicle is used to protect the mask from contaminant particles, then the mask is protected from damage and contamination, but exposure radiation energy consumption increases

Engineering Contradiction:

Improvemask protection from contaminant particlesVSAvoidexposure radiation energy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces the mechanical solid pellicle system with an optical field-based particle manipulation system. Laser beams create optical forces (radiation pressure and gradient forces) to trap and remove particles without physical contact, eliminating the mechanical pellicle structure that caused CD errors and energy loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extracts and removes contaminant particles from the exposure path using optical forces before they can reach the mask. By actively removing particles rather than using a pellicle to block them, the system eliminates the energy-absorbing barrier while maintaining protection.

Inventive Principle:

Principle #2Taking out (Extraction)

3Productivity

If reflective optics are used instead of refractive optics due to high absorption of EUV light by all materials, then the lithography process can proceed with EUV light, but the system complexity increases

Engineering Contradiction:

Improvelithography process capability with EUV lightVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts and removes contaminant particles from the exposure path using optical forces before they can reach the mask. By actively removing particles rather than using a pellicle to block them, the system eliminates the energy-absorbing barrier while maintaining protection.

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 solution enhances the yield and quality of the lithography process by effectively preventing contaminant particles from reaching the mask, eliminating the need for a solid pellicle and reducing critical dimension errors and exposure radiation energy consumption.

Implementation Method 1

The optical module is configured to optically form an invisible pellicle over the mask to protect the mask from contaminant particles

Methodology Applied

Scientific EffectRadiation pressure: Radiation Pressure

Implementation Method 2

providing a pair of laser beams to scan back and forth over a surface of the mask to optically form an invisible pellicle over the surface

Methodology Applied

Scientific EffectOptical tweezers: Optical Tweezers

Data Source

PatentUS10488766B2Lithography system having invisible pellicle over mask

Publication Date: 2019.11.26 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A lithography system is provided. The lithography system includes a mask and an optical module. The optical module is configured to optically form an invisible pellicle over the mask to protect the mask from contaminant particles. As a solid pellicle used in the prior arts is omitted, the critical dimension (CD) error from the boarder effect due to reflection of some light by the solid pellicle and the exposure radiation energy consumption caused by the solid pellicle can be avoided.