Resist Underlayer Composition for Lithography Pattern Collapse
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Solution Overview
Problem
In ArF liquid immersion lithography and extreme ultraviolet (EUV) lithography, resist patterns with fine line widths are prone to collapse due to a small contact area between the resist pattern and the ground, which existing resist underlayer films with lactone structures fail to adequately prevent.
Innovation Solution
A resist underlayer film-forming composition comprising a polymer with specific structural units, such as those represented by Formulas (1a), (1b), or (2), and an organic solvent, which reform the surface state of the underlayer film to be basic, thereby enhancing adhesiveness and preventing undercut formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a resist underlayer film with a lactone structure is used, then adhesiveness to the resist pattern is improved, but collapse of the resist pattern still occurs in fine lithography processes
Solution Approach 1:
The invention changes the chemical parameter of the underlayer film surface from acidic to basic by introducing a basic group-containing compound. This parameter change transforms the interface chemistry to prevent undercut formation, thereby preventing pattern collapse while maintaining the adhesiveness provided by the lactone structure.
Solution Approach 2:
The invention creates a composite underlayer film system combining a lactone-containing polymer (for adhesiveness) with a basic group-containing compound (for surface state modification). This composite approach integrates two functional components to simultaneously achieve both adhesiveness and collapse prevention.
2Manufacturing precision
If the contact area between resist pattern and ground is reduced for finer line widths, then manufacturing precision is improved, but the aspect ratio increases causing pattern collapse
Solution Approach 1:
The invention changes the chemical state parameter of the underlayer film surface to basic, which prevents undercut formation at the resist-underlayer interface. This chemical parameter change strengthens the effective support for high aspect ratio patterns, enabling finer line widths without collapse.
3Shape
If the chemical state of the interface is acidic, then the resist pattern shape becomes undercut, but the contact area with the underlayer film decreases, reducing adhesiveness
Solution Approach 1:
The invention inverts the conventional acidic interface chemistry to a basic chemical state by introducing a basic group-containing compound. This inversion prevents undercut formation and maintains both the desired pattern shape and sufficient contact area for adhesiveness.
Data Source
AI summary
A composition forms a resist underlayer film showing improved adhesiveness to a resist pattern. A resist underlayer film-forming composition for lithography, including: a polymer that has a structure of Formula (1a), Formula (1b), or Formula (2) below on an end of the polymer; and an organic solvent:where R1 is a hydrogen atom or a methyl group; each of R2 and R3 is independently a hydrogen atom or an organic group such as a hydrocarbon group, etc., the hydrocarbon group optionally has at least one of a hydroxy group and a methylthio group as substituent(s); R4 is a hydrogen atom or a hydroxy group; Q1 is an arylene group; v is 0 or 1; y is an integer of 1 to 4; w is an integer of 1 to 4; x1 is 0 or 1; and x2 is an integer of 1 to 5.