Resist Underlayer Film Composition for Dense, Etch-Resistant Patterning
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Solution Overview
Problem
Existing resist underlayer films in semiconductor production face challenges such as intermixing with resist layers, low dry-etching resistance, and pattern collapse due to insufficient film thickness and hardness, especially with the advancement of semiconductor integration and the use of shorter wavelength light sources.
Innovation Solution
A resist underlayer film-forming composition using a novolak resin with specific chemical groups substituted for hydrogen atoms on aromatic rings, enhancing film density, hardness, and etching resistance, and incorporating crosslinkers and acids to improve film properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the resist film thickness is decreased to achieve finer patterns, then the resolution is improved, but the film becomes insufficient for substrate processing and patterns collapse
Solution Approach 1:
The invention divides the protective function into two separate layers: a thin resist layer for pattern formation and a thicker underlayer film for structural support and substrate protection. This segmentation allows the resist to be thin enough for high-resolution patterning while the underlayer provides sufficient thickness to prevent pattern collapse and enable substrate processing.
Solution Approach 2:
The underlayer film acts as an intermediary between the thin resist layer and the substrate. It receives the transferred pattern from the resist and provides the mechanical strength needed for substrate processing, mediating between the conflicting requirements of thin resist for resolution and thick film for structural integrity.
2Productivity
If conventional resist underlayer films are used, then the etching rate is high, but the selection ratio of dry etching rate is not close to that of the resist
Solution Approach 1:
The invention changes the chemical composition parameters of the underlayer film by using a novolak resin with specific aromatic ring structures and substituents. This compositional change adjusts the etching characteristics to achieve a selection ratio of dry etching rate close to that of the resist, enabling precise pattern transfer while maintaining efficient etching speed.
3Ease of manufacture
If the resist underlayer film is formed with insufficient density and hardness, then the application is simple, but intermixing with resist layer occurs and dry-etching resistance is low
Solution Approach 1:
The underlayer film is formed as a composite material consisting of novolak resin combined with specific additives including crosslinkers and etching resistance enhancers. This composite structure provides both the simplicity of a single-step application process and the enhanced properties of high density, hardness, and dry-etching resistance needed to prevent intermixing and maintain pattern integrity.
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 composition allows for precise resist pattern formation without intermixing, reduces reflection, and provides high dry-etching resistance, preventing pattern collapse and enabling efficient substrate processing.
Implementation Method 1
a polymer including a cyclic structure such as novolak has been widely used... a polymer having a crosslink structure
Implementation Method 2
chemical groups (a) that cause an increase in mass upon oxidation
Implementation Method 3
chemical groups (c) that induce phase separation during curing
Data Source
AI summary
A resist underlayer film formation composition including a novolak resin that has a repeating unit structure represented by the following formula (1). (In formula (1), groups A and B are organic groups which each have an aromatic ring, a fused aromatic ring, or a fused aromatic heterocycle and have a structure in which two or more mono- or divalent chemical groups selected from the group consisting of chemical groups (a) that cause an increase in mass upon oxidation, groups (b) that form a crosslink upon heating, and groups (c) that induce phase separation during curing have replaced hydrogen atoms on the ring(s) contained in group A and/or B.) The composition further includes a crosslinking agent and an acid and/or acid generator. A production process is provided in which the resist underlayer film formation composition is applied to a semiconductor substrate and burned to obtain a resist underlayer film.