Isosorbide Nitrate Ester Resist Suppresses Acid Diffusion

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Solution Overview

Problem

Current chemically amplified resist compositions face challenges in achieving high sensitivity, resolution, and minimal edge roughness for microelectronic device manufacturing, particularly as feature sizes reduce, due to issues with acid diffusion and sensitivity tradeoffs.

Innovation Solution

A positive resist composition is developed using a polymer with recurring units of isosorbide nitrate ester, which suppresses acid diffusion and enhances dissolution contrast, sensitivity, and resolution, while maintaining minimal edge roughness, by incorporating acid labile groups and specific monomers to improve acid generation efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If the accelerating voltage is increased to improve line width accuracy, then resolution is improved, but resist film sensitivity decreases

Engineering Contradiction:

Improveline width accuracyVSAvoidresist film sensitivity

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters of the resist film by incorporating specific compounds (compound A and compound B) that enhance acid generation efficiency. This allows the resist to maintain high sensitivity even at elevated accelerating voltages of 30-50 kV, resolving the contradiction between resolution improvement and sensitivity loss.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite resist system by combining multiple components: base resist material, compound A (acid generator), and compound B (sensitivity enhancer). This composite approach enables simultaneous achievement of high resolution and high sensitivity that cannot be obtained with single-material systems.

Inventive Principle:

Principle #40Composite materials

2Reliability

If chemically amplified resist compositions are designed to enhance sensitivity and contrast by acid diffusion, then sensitivity is improved, but acid diffusion control becomes problematic for fine patterns

Engineering Contradiction:

ImprovesensitivityVSAvoidacid diffusion control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent introduces compound B which locally enhances acid generation at specific sites within the resist film. This localized acid generation mechanism allows fine patterns to be formed with precise control, as the acid diffusion is concentrated rather than widespread, thereby maintaining both sensitivity and manufacturing precision.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Compound B acts as an intermediary substance that mediates between the acid generator and the base resist material. It controls the acid diffusion process by providing a controlled release mechanism, preventing uncontrolled spread of acid while maintaining the necessary chemical amplification for high sensitivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Manufacturing precision

If the post-exposure bake temperature and time are reduced to minimize acid diffusion, then resolution is improved, but sensitivity and contrast are drastically reduced

Engineering Contradiction:

ImproveresolutionVSAvoidsensitivity

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent incorporates acid generators and sensitivity enhancers into the resist film before exposure. This preliminary preparation allows the resist to achieve high sensitivity and contrast even with minimal post-exposure bake treatment, as the chemical amplification is already in place to enhance the exposure effects without requiring extended heating.

Inventive Principle:

Principle #10Preliminary action

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 resist composition achieves high sensitivity, resolution, and controlled acid diffusion, forming patterns with good profiles and minimal edge roughness, suitable for advanced lithography processes such as EB and EUV lithography.

Implementation Method 1

an acid generator capable of generating a bulky acid... the addition of an acid generator capable of generating a bulky acid is an effective means for suppressing acid diffusion

Methodology Applied

Scientific EffectPhotochemical decomposition: Photodissociation

Implementation Method 2

With respect to high-energy radiation of very short wavelength such as electron beam (EB) or x-ray, hydrocarbons and similar light elements used in resist materials have little absorption

Methodology Applied

Scientific EffectRadiation absorption: Absorption (EM radiation)

Data Source

PatentUS9482949B2Positive resist composition and patterning process

Publication Date: 2016.11.01 SHIN ETSU CHEMICAL CO LTD

AI summary

A positive resist composition is provided comprising a polymer comprising recurring units having a carboxyl or phenolic hydroxyl group substituted with an acid labile group and recurring units of isosorbide nitrate ester, and having a Mw of 1,000-500,000. The resist composition has a satisfactory effect of suppressing acid diffusion and a high resolution, and forms a pattern of good profile and minimal edge roughness after exposure.