Polyvalent Ammonium Salt Curing in Silicon-Containing Resist Underlayers

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Solution Overview

Problem

Existing photoresist compositions face challenges in achieving high resolution and etching resistance while maintaining pattern integrity, leading to issues such as pattern collapse and degradation in line width roughness (LWR) and critical dimension uniformity (CDU) in ultra-fine patterns, particularly with the advent of ArF immersion lithography and EUV lithography.

Innovation Solution

A polyvalent ammonium salt compound is used as a curing catalyst in a composition for forming a silicon-containing resist underlayer film, promoting thermosetting and enhancing the etching rate and LWR/CDU properties, while minimizing diffusion to the resist upper layer film.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a photoresist composition uses a resin with low light absorption (such as novolak resin or polyhydroxystyrene) to improve resolution at shorter exposure wavelengths, then resolution performance is improved, but etching resistance decreases and etching rate increases

Engineering Contradiction:

Improveresolution performanceVSAvoidetching resistance

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention divides the resist system into two separate layers: a photoresist film for pattern formation and a silicon-containing resist underlayer film for etching resistance. This segmentation allows each layer to be optimized independently - the photoresist film uses low light-absorption resin for high resolution, while the underlayer provides the necessary etching resistance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The silicon-containing resist underlayer film acts as an intermediary layer between the photoresist film and the substrate. It serves as a protective mask during dry etching, shielding the substrate from excessive etching while allowing the photoresist pattern to be accurately transferred

Inventive Principle:

Principle #24Intermediary (Mediator)

2Shape

If the photoresist film thickness is reduced to maintain aspect ratio and prevent pattern collapse during development, then pattern collapse is reduced, but etching resistance decreases further

Engineering Contradiction:

Improvepattern integrityVSAvoidetching resistance

Core Design Contradiction:

ShapeVSReliability

Solution Approach 1:

By separating the photoresist film from the etching protection function, the invention allows the photoresist film to be thin (maintaining pattern integrity) while the silicon-containing underlayer provides the necessary etching resistance

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The silicon-containing resist underlayer film is formed beforehand to provide a cushion of etching resistance, protecting both the substrate and the thin photoresist film during the dry etching process

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Reliability

If a multilayer resist method is used with a silicon-containing resist underlayer film to improve etching resistance, then etching resistance is improved, but residue from the underlayer film may remain and cause defects

Engineering Contradiction:

Improveetching resistanceVSAvoidresidue-related defects

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The invention carefully controls the composition parameters of the silicon-containing underlayer film, specifically using polysiloxane with controlled molecular weight and crosslinking density, to achieve optimal etching rate and complete removal without residue

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The silicon-containing underlayer film is designed with specific local properties - it has high etching resistance during the main etching process but becomes selectively removable afterward to prevent residue defects

Inventive Principle:

Principle #3Local quality

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 polyvalent ammonium salt compound improves LWR and CDU in ultra-fine patterns, enabling effective pattern transfer and reducing residue-related defects, thus facilitating the formation of high-quality semiconductor device patterns.

Implementation Method 1

promoting thermosetting

Methodology Applied

Scientific EffectThermosetting:

Implementation Method 2

A polyvalent ammonium salt compound is used as a curing catalyst in a composition for forming a silicon-containing resist underlayer film

Methodology Applied

Scientific EffectCuring catalyst: Catalysis

Data Source

PatentUS20250289931A1Polyvalent ammonium salt compound, composition for forming silicon-containing resist underlayer film, and patterning process

Publication Date: 2025.09.18 SHIN ETSU CHEMICAL CO LTD

AI summary

The present invention is a polyvalent ammonium salt compound having two or more ammonium ions per molecule, the polyvalent ammonium salt compound being represented by the following general formula (A-1). This can provide: a composition for forming a silicon-containing resist underlayer film with which it is possible to form a silicon-containing resist underlayer film that has an appropriate etching rate and can improve LWR and CDU in an ultra-fine pattern in a multilayer resist method; a polyvalent ammonium salt compound to be contained in the composition; and a patterning process using the composition.