Photomask Pellicle Shading Layout for Foreign Matter Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Photomasks with negative resist transfer patterns experience significant foreign matter adhesion issues due to stray light exposure, leading to reduced usability, especially with shorter wavelengths of exposure light used in modern semiconductor manufacturing.

Innovation Solution

Incorporating a light-shading film region below the pellicle frame, which prevents adhesives and components from being irradiated by stray light, thereby reducing gas generation and deposition on the photomask, particularly effective with high-output lasers of 200 nm or less wavelength.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a photomask uses negative resist with exposed transparent substrate in peripheral regions, then drawing time is shortened and pattern formation is improved, but foreign matter adhesion increases due to stray light exposure

Engineering Contradiction:

Improvedrawing timeVSAvoidforeign matter adhesion

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A light-shading film is introduced as an intermediary element between the exposed transparent substrate and the adhesive/pellicle frame. This film intercepts stray light before it reaches the adhesive, preventing the harmful photochemical reactions that cause foreign matter adhesion, while allowing the negative resist process benefits to be maintained

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful effect of stray light exposure into a beneficial selective shading effect. The light-shading film is strategically placed to intercept only the harmful peripheral stray light that would cause adhesion problems, while allowing necessary light exposure in other regions to proceed unchanged

Inventive Principle:

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

2Ease of manufacture

If adhesive is applied to transparent substrate for pellicle mounting, then pellicle attachment is achieved, but adhesive reacts with stray light to generate deposited substances

Engineering Contradiction:

Improvepellicle attachmentVSAvoiddeposited substances

Core Design Contradiction:

Ease of manufactureVSObject-generated harmful factors

Solution Approach 1:

The light-shading film serves as a protective intermediary layer between the adhesive and stray light. It is positioned to block stray light from reaching the adhesive, preventing photochemical reactions that would generate deposited substances, while allowing the adhesive to maintain its bonding function

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light-shading film provides preliminary protection by intercepting stray light before it can interact with the adhesive. This preventive measure stops the harmful photochemical reactions before they can occur, eliminating the generation of deposited substances

Inventive Principle:

Principle #9Preliminary anti-action

3Manufacturing precision

If high-output laser beams with short wavelengths are used for exposure, then resolution is improved, but foreign matter deposition increases due to enhanced stray light effects

Engineering Contradiction:

ImproveresolutionVSAvoidforeign matter deposition

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The light-shading film acts as a wavelength-selective intermediary that effectively intercepts high-energy short-wavelength stray light from laser exposure systems. This prevents the enhanced photochemical reactions that occur with high-output laser beams, eliminating foreign matter deposition while maintaining the resolution benefits of short-wavelength exposure

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Significantly reduces foreign matter adhesion and extends the usable life of photomasks by preventing gas generation and deposition, maintaining photomask quality even with exposure to shorter wavelengths.

Implementation Method 1

a light-shading film having a light-shading property to an exposure light of the exposure apparatus

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 2

a pellicle frame to which an adhesive is applied only on an outer surface

Methodology Applied

Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20070287077A1Photomask and exposure method

Publication Date: 2007.12.13 PANASONIC SEMICON SOLUTIONS CO LTD

AI summary

To provide a photomask capable of preventing a foreign matter generation in using the photomask, and an exposure method using this photomask. The photomask includes a transparent substrate 2; a transfer pattern 4 formed in a main region 3 of a center portion of the transparent substrate 2; a light-shading band region 5 provided adjacent to the main region 3 in the outer peripheral region of the main region 3; and a pellicle 6 formed by adhering a pellicle film 6a to a pellicle frame 6b by an adhesive 8a, wherein this pellicle 6 is adhered onto a light-shading region 7 consisting of a light-shading film formed in the outer peripheral region of the main region 3, through an adhesive 8b.