Charged Particle Beam Writing Apparatus Resist Heating Mitigation

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Solution Overview

Problem

The increasing demand for high precision in microlithography for semiconductor devices leads to issues with resist heating due to higher electron beam current density, causing line width accuracy degradation and increased writing time.

Innovation Solution

A charged particle beam writing apparatus and method that calculates the total charge amount and representative temperature of each deflection region, modulates the electron beam dose using deflectors of multiple levels, and adjusts the writing process to mitigate resist heating by optimizing the dose and writing schedule.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If electron beam current density is increased to shorten writing time, then productivity is improved, but resist heating occurs causing manufacturing precision to deteriorate

Engineering Contradiction:

Improvewriting speedVSAvoidline width accuracy

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The system calculates the total charge amount and representative temperature of each minimum deflection region before writing, and pre-modulates the dose based on predicted heat accumulation from previously written regions. This preliminary dose modulation prevents resist heating effects before they occur during actual writing, enabling high current density operation without precision loss

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically changes the dose parameter based on the calculated representative temperature of each minimum deflection region. By modulating the dose according to temperature conditions, the system maintains manufacturing precision while operating at higher current densities for improved productivity

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If electron beam current density is increased to maintain line width accuracy, then manufacturing precision is improved, but writing time increases causing productivity to deteriorate

Engineering Contradiction:

Improveline width accuracyVSAvoidwriting time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system divides the writing region into multiple minimum deflection regions and applies different dose modulations to each region based on its local heat accumulation characteristics. This localized dose adjustment allows high current density operation in regions with low heat accumulation while maintaining precision in regions prone to heating, thereby improving overall productivity without sacrificing accuracy

Inventive Principle:

Principle #3Local quality

3Manufacturing precision

If number of electron beam shots is increased to reduce shot noise, then manufacturing precision is improved, but writing time increases causing productivity to deteriorate

Engineering Contradiction:

Improvepattern edge roughnessVSAvoidwriting time

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The system modulates the dose parameter based on temperature conditions, which allows maintaining manufacturing precision through optimized dose distribution rather than simply increasing shot number. This parameter-based control reduces writing time while maintaining pattern quality

Inventive Principle:

Principle #35Parameter changes

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 pattern dimension variations caused by resist heating, allowing for faster and more accurate writing of semiconductor patterns, thereby maintaining precision and reducing writing time.

Implementation Method 1

there is a problem of a phenomenon referred to as 'resist heating' in which the resist sensitivity changes due to overheating of the substrate

Methodology Applied

Scientific EffectResist heating: Heating

Implementation Method 2

calculate a representative temperature of the each minimum deflection region based on heat transfer from other minimum deflection regions having been written before the each minimum deflection region is written

Methodology Applied

Scientific EffectHeat transfer: Conduction (thermal)

Data Source

PatentUS8563953B2Charged particle beam writing apparatus and charged particle beam writing method

Publication Date: 2013.10.22 NUFLARE TECH INC

AI summary

A charged particle beam writing apparatus includes a unit calculating a total charge amount of charged particle beams irradiating each minimum deflection region in deflection regions having different deflection sizes respectively deflected by deflectors of a plurality of levels for deflecting charged particle beams, a unit calculating a representative temperature of the each minimum deflection region based on heat transfer from other minimum deflection regions having been written before the each minimum deflection region is written, a unit inputting a first dose of a shot of each charged particle beam irradiating the each minimum deflection region, and modulating the first dose by using the representative temperature of the each minimum deflection region, and a unit including the deflectors of a plurality of levels and writing a pattern in the each minimum deflection region with a second dose, which has been modulated, by using the deflectors of a plurality of levels.