Doped Carbon Underlayer for EUV Photoresist Adhesion and Etch Selectivity

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Solution Overview

Problem

Extreme ultraviolet (EUV) lithography faces challenges with traditional chemically amplified resist systems due to line edge and line width roughness, sensitivity limitations, and delamination issues between EUV photoresist and hardmask materials, requiring improved adhesion and etch selectivity.

Innovation Solution

A thin underlayer of hydronated carbon doped with oxygen, silicon, nitrogen, tungsten, boron, iodine, or chlorine is deposited between the substrate and EUV inorganic photoresist, enhancing adhesion and reducing radiation dose, while also providing improved etch selectivity and reduced line edge and line width roughness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If EUV inorganic photoresist is deposited directly on hardmask materials, then the structure is simpler, but adhesion is poor causing delamination

Engineering Contradiction:

Improvestructure complexityVSAvoidadhesion

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A thin underlayer of hydronated carbon doped with oxygen, silicon, nitrogen, tungsten, boron, iodine, or chlorine is deposited between the substrate and EUV inorganic photoresist. This underlayer acts as an intermediary that enhances adhesion between the photoresist and substrate, preventing delamination while maintaining structural simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If traditional chemically amplified resist systems are used, then the process is established, but line edge and line width roughness occur

Engineering Contradiction:

Improveprocess establishmentVSAvoidline edge and line width roughness

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent changes the chemical composition parameters of the underlayer by doping hydronated carbon with specific elements (oxygen, silicon, nitrogen, tungsten, boron, iodine, or chlorine). These parameter changes in the underlayer composition improve the performance of EUV inorganic photoresist, reducing line edge and line width roughness while maintaining process establishability.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If EUV inorganic photoresist is used directly on Spin-On-Carbon stacks, then fewer layers are needed, but etch selectivity is insufficient

Engineering Contradiction:

Improvenumber of layersVSAvoidetch selectivity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The underlayer of hydronated carbon doped with specific elements serves as an intermediary layer that provides improved etch selectivity. This allows the system to maintain a simple two-layer structure (substrate + underlayer + photoresist) while achieving the etch selectivity that would otherwise require additional functional layers.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Reliability

If higher radiation dose is applied, then effective photoresist exposure is achieved, but dose to size performance worsens

Engineering Contradiction:

Improvephotoresist exposure effectivenessVSAvoiddose to size performance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The doping of hydronated carbon with specific elements (particularly iodine, boron, or tungsten) changes the radiation interaction parameters of the underlayer. This enhances the generation of secondary electrons upon radiation exposure, improving photoresist exposure effectiveness at lower doses and achieving better dose to size performance.

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

The underlayer improves the dose to size performance, etch selectivity, and reduces line edge and line width roughness, achieving comparable or better results than EUV inorganic photoresist directly on Spin-On-Carbon stacks, with decreased required dose and enhanced adhesion.

Implementation Method 1

the underlayer is configured to: increase adhesion between the substrate and the imaging layer

Methodology Applied

Scientific EffectAdhesion: Adhesive

Implementation Method 2

the underlayer includes the hydronated carbon doped with iodine configured to improve generation of secondary electrons upon exposure to radiation

Methodology Applied

Scientific EffectSecondary electron generation: Photoelectric Effect

Implementation Method 3

the underlayer includes a vapor deposited film of hydronated carbon doped with O, Si, N, W, B, I, Cl, or a combination of two or more of any of these

Methodology Applied

Scientific EffectVapor deposition: Physical Vapour Deposition

Data Source

PatentUS11988965B2Underlayer for photoresist adhesion and dose reduction

Publication Date: 2024.05.21 LAM RES CORP

AI summary

This disclosure relates generally to a patterning structure including an underlayer and an imaging layer, as well as methods and apparatuses thereof. In particular embodiments, the underlayer provides an increase in radiation absorptivity and/or patterning performance of the imaging layer.