Thick-Film Resist Composition for Fine Pattern Rectangularity
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Solution Overview
Problem
Conventional non-chemically amplified and chemically amplified positive resist compositions face challenges in forming very fine resist patterns, particularly with dimensions less than 400 nm, due to poor rectangular formability, verticality issues, and pattern collapse, and are unsuitable for high-resolution applications.
Innovation Solution
A positive resist composition comprising a polymer compound with specific structural units derived from hydroxystyrene and acrylate esters, an onium salt-based acid generator, and a nitrogen-containing organic compound, which enhances alkali solubility and improves resist pattern shape and dry etching resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional non-chemically amplified positive resist compositions are used, then the resist film can be formed with simple composition, but the rectangular formability and verticality are poor making very fine patterns (<400 nm) unformable
Solution Approach 1:
The patent uses a composite resin composition containing both polyhydroxystyrene (PHS) based resin and acrylic-based resin, combining the advantages of both materials. The PHS resin provides good adhesion and etching resistance, while the acrylic resin contributes to rectangular formability and verticality, enabling very fine pattern formation with improved manufacturing precision
Solution Approach 2:
The patent optimizes the molecular weight parameters of the resin components (PHS resin: 50,000-200,000, acrylic resin: 10,000-50,000) and their weight ratios (PHS: 70-99 wt%, acrylic: 1-30 wt%) to achieve the desired balance between rectangular formability, verticality, and pattern fidelity for very fine dimensions
2Manufacturing precision
If chemically amplified positive resist compositions are used, then high resolution can be achieved, but pattern collapse occurs due to poor structural support in thick films
Solution Approach 1:
The patent creates a composite resist system where the PHS-based resin provides strong structural support preventing pattern collapse, while the acrylic-based resin components contribute to high resolution patterning. This composite approach maintains pattern integrity in thick films while achieving very fine dimensional control
Solution Approach 2:
The patent introduces a gradient structure in the resist film with different molecular weights and compositions - the lower molecular weight acrylic resin (10,000-50,000) enhances resolution in the exposed regions, while the higher molecular weight PHS resin (50,000-200,000) provides structural strength throughout the film to prevent collapse
3Strength
If thick-film resist is formed to provide structural support, then pattern collapse is prevented, but rectangular formability and verticality deteriorate
Solution Approach 1:
The patent optimizes the molecular weight of the acrylic-based resin to 10,000-50,000, which is lower than conventional thick-film resins. This parameter change enables the formation of thick films with sufficient structural support while maintaining excellent rectangular formability and verticality, as the lower molecular weight resin flows better during spin coating and develops more uniformly
4Strength
If resist film thickness is increased to 1 μm or greater for thick-film applications, then structural support is improved, but manufacturing precision for very fine patterns deteriorates
Solution Approach 1:
The patent uses a bimodal molecular weight distribution strategy: PHS resin with high molecular weight (50,000-200,000) provides structural support for thick films, while acrylic resin with lower molecular weight (10,000-50,000) ensures precise pattern formation. This parameter optimization enables thick-film resist (1 μm or greater) to maintain very fine pattern dimensions with high manufacturing precision
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 enables the formation of thick-film resist patterns with favorable shape and rectangular formability, suitable for high-resolution applications, including MEMS production, with improved heat resistance and etching resistance.
Implementation Method 1
a positive chemically amplified resist includes a resin component that exhibits increased alkali solubility under the action of acid and an acid generator component that generates acid upon exposure, and during resist pattern formation, when acid is generated from the acid generator as a result of exposure, the exposed portions become alkali-soluble
Data Source
AI summary
A positive resist composition for forming a thick-film resist having a film thickness of 1 to 15 μm, the composition comprising: a resin component (A) that includes a polymer compound (A1), which has a weight average molecular weight of 20,000 to 50,000, and includes a structural unit (a1) derived from a hydroxystyrene and a structural unit (a2) derived from an acrylate ester containing an acid dissociable, dissolution inhibiting group, an acid generator component (B) that generates acid upon exposure and includes an onium salt-based acid generator having an anion moiety represented by general formula (I): R4″SO3− (wherein, R4″ represents a linear or branched alkyl group or fluoroalkyl group of 4 carbon atoms), and a nitrogen-containing organic compound (D) that includes a tertiary aliphatic amine.