Conductive Substrate Mask Inspection for Electron Beam Charging

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Solution Overview

Problem

The existing methods for inspecting photo mask substrates, particularly with electron beams, face challenges in detecting defects due to charging and contrast deficiencies, especially in multilayered resist structures with thick insulating films, leading to reduced detection sensitivity.

Innovation Solution

Transferring a mask pattern onto a conductor or semiconductor substrate with a conductive surface pattern, and irradiating it with an electron beam to detect secondary, reflected, or backscattered electrons, thereby acquiring an image for inspection and verifying exposure conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If electron beam inspection is used on multilayered resist structures with thick insulating films, then high-resolution inspection capability is achieved, but detection sensitivity deteriorates due to charging and contrast deficiency

Engineering Contradiction:

Improveinspection resolutionVSAvoiddetection sensitivity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the electrical conductivity parameter of the substrate by using conductive substrates (such as silicon substrates with conductive layers) instead of insulating substrates. This parameter change eliminates charging effects during electron beam inspection, thereby maintaining high detection sensitivity while preserving the high-resolution capability of electron beam inspection for multilayered resist structures.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If resist pattern inspection is performed on multilayered resist structures, then pattern transfer capability is maintained, but contrast deficiency occurs due to thick insulating film coating

Engineering Contradiction:

Improvepattern transfer qualityVSAvoidimage contrast

Core Design Contradiction:

Manufacturing precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent changes the electrical property parameter of the substrate system by employing conductive substrates, which fundamentally alters the electron beam interaction characteristics. This eliminates the contrast deficiency caused by thick insulating films, as the conductive substrate allows proper electron beam penetration and signal generation, thereby improving image contrast while maintaining pattern transfer quality.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces a conductive layer as an intermediary between the electron beam and the multilayered resist structure. This conductive intermediary (such as a silicon substrate with conductive properties) mediates the electron beam interaction, preventing charging effects and improving electron beam penetration, thereby enhancing image contrast without compromising the integrity of the multilayered resist structure inspection.

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

This approach enhances inspection sensitivity and contrast, improves pattern transfer quality, and ensures appropriate exposure conditions, leading to more accurate and reliable mask pattern inspection and semiconductor device manufacturing.

Implementation Method 1

irradiating the sample with an electron beam to detect at least one of a secondary electron, a reflected electron and a backscattered electron generated from the surface of the sample

Methodology Applied

Scientific EffectSecondary electron emission: Electron Impact Desorption

Implementation Method 2

irradiating the sample with an electron beam to detect at least one of a secondary electron, a reflected electron and a backscattered electron

Methodology Applied

Scientific EffectElectron reflection: Reflection

Implementation Method 3

irradiating the sample with an electron beam to detect at least one of a secondary electron, a reflected electron and a backscattered electron

Methodology Applied

Scientific EffectBackscattering: Compton Scattering

Data Source

PatentUS7674570B2Mask pattern inspection method, exposure condition verification method, and manufacturing method of semiconductor device

Publication Date: 2010.03.09 KIOXIA CORP

AI summary

A mask pattern inspection method includes: transferring a mask pattern onto a conductor substrate or a semiconductor substrate; preparing a sample including a substrate surface pattern in an electrically conductive state to the substrate, the substrate surface pattern being constituted of a convex pattern or a concave pattern each having a shape in accordance with the transferred mask pattern, or a surface layer obtained by filling the concave pattern with a material; irradiating the sample with an electron beam to detect at least one of a secondary electron, a reflected electron and a backscattered electron generated from the surface of the sample, thereby acquiring an image of the sample surface; and inspecting the mask pattern on the basis of the image.