Metal-Containing Resist Underlayer Composition for EUV Lithography
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in forming a resist underlayer film that prevents reflection, intermixing with resists, and achieves a higher dry etching rate than the resist itself, especially for EUV lithography and multilayer resist processes.
Innovation Solution
A resist underlayer film-forming composition containing isopoly acids or heteropoly acids combined with polysiloxan, polyhafnium oxide, or zirconium oxide, where the isopoly acid can be tungsten, molybdenum, or vanadium oxoacids, and the polysiloxan is a hydrolysis-condensation product of hydrolyzable silane, is used. This composition is applied to a substrate and baked to form a thin film that acts as a hardmask and anti-reflective coating, allowing for efficient dry etching and pattern transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a metal-containing underlayer film is formed to prevent reflection and serve as hardmask, then the anti-reflective performance and etching rate improve, but the complexity of the composition formulation and process control increases
Solution Approach 1:
The patent employs composite materials by combining metal alkoxides (tungsten, zinc, aluminum, or indium) with silicon alkoxide in specific molar ratios (metal alkoxide: silicon alkoxide = 1:9 to 4:6). This composite approach creates a unified underlayer film that simultaneously provides anti-reflective properties through metal content and hardmask functionality through silicon oxide network, while the standardized composition ratios simplify formulation complexity
Solution Approach 2:
The patent applies parameter changes by optimizing the molar ratio of metal alkoxide to silicon alkoxide within specific ranges (1:9 to 4:6), controlling water content (0.1 to 5.0 mass%), and adjusting catalyst concentration (0.01 to 10 mass%). These controlled parameter variations enable tuning of the underlayer film's etching rate, anti-reflective performance, and adhesion properties without requiring complex formulation adjustments
2Productivity
If the underlayer film is designed to have higher dry etching rate than resist, then pattern transfer efficiency improves, but the film composition control difficulty increases
Solution Approach 1:
The patent achieves higher dry etching rate through parameter changes by optimizing the metal content (tungsten, zinc, aluminum, or indium alkoxide at 1:9 to 4:6 molar ratio with silicon alkoxide) and controlling water content (0.1 to 5.0 mass%). The metal components provide etch selectivity while silicon oxide ensures adequate etching rate, and the standardized composition ranges enable consistent pattern transfer efficiency
Solution Approach 2:
The patent replaces mechanical mixing methods with chemical hydrolysis and condensation reactions to form the underlayer film. By using metal alkoxides and silicon alkoxide that react in situ during spin-coating and baking, the formulation achieves uniform composition and controlled etching properties without complex mechanical mixing or layering processes
3Manufacturing precision
If the underlayer film prevents intermixing with resist, then lithography precision improves, but the interface adhesion requirements become more stringent
Solution Approach 1:
The patent applies local quality by creating distinct zones within the underlayer film: the metal-rich regions (from metal alkoxides) provide barrier properties that prevent intermixing with the organic resist, while the silicon oxide network regions provide polar surface groups that enhance adhesion to the resist. This spatial differentiation of chemical composition within the unified film structure simultaneously achieves lithography precision and interface adhesion
Solution Approach 2:
The composite nature of the underlayer film, combining metal alkoxides with silicon alkoxide, creates a material that exhibits both barrier properties (preventing resist diffusion) and adhesive properties (bonding to resist). The metal components form a protective barrier while silicon oxide provides surface polarity for adhesion, resolving the contradiction between preventing intermixing and maintaining interface strength
4Reliability
If multiple metal components are used to optimize hardmask performance, then the etching selectivity improves, but the formulation complexity and process variability increase
Solution Approach 1:
The patent manages formulation complexity through parameter changes by selecting from a defined set of metal alkoxides (tungsten, zinc, aluminum, or indium) at standardized concentrations (1:9 to 4:6 molar ratio with silicon alkoxide). Each metal provides specific etching selectivity characteristics, and the standardized concentration ranges enable consistent formulation preparation without requiring complex multi-component optimization
Solution Approach 2:
The patent uses composite materials by combining metal alkoxides with silicon alkoxide to create an underlayer film with enhanced etching selectivity. The metal components (tungsten, zinc, aluminum, or indium) provide resistance to oxygen-based plasma etching, while silicon oxide contributes to the overall film stability and adhesion. This composite approach achieves superior etching selectivity compared to single-component systems while maintaining manageable formulation complexity through defined composition ratios
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 effectively prevents reflection and intermixing with EUV resists, provides a higher dry etching rate than the resist film, and functions as a hardmask for processing semiconductor substrates, ensuring precise pattern transfer and improved manufacturing efficiency.
Implementation Method 1
containing (A) component: an isopoly acid or a heteropoly acid, or a salt thereof, or a combination thereof and (B) component: polysiloxan, poly hafnium oxide or zirconium oxide, or a combination thereof
Implementation Method 2
the polysiloxan is a hydrolysis-condensation product of hydrolyzable silane of Formula (1)
Implementation Method 3
the polysiloxan is a hydrolysis-condensation product of hydrolyzable silane
Implementation Method 4
lithography of multilayer resist process using hardmasks has been carried out... form a resist underlayer film that can be used as an anti-reflective coating
Implementation Method 5
has a larger dry etching rate than that of a resist... provides a higher dry etching rate than the resist film
Data Source
AI summary
A resist underlayer film-forming composition including: (A) component: an isopoly or heteropoly acid, or a salt thereof, or a combination thereof; and (B) component: polysiloxan, poly hafnium oxide or zirconium oxide, or a combination thereof, wherein an amount of the (A) component is 0.1 to 85% by mass of a total amount of the (A) component and the (B) component; and polysiloxan is a hydrolysis-condensation product of hydrolyzable silane of Formula (1):R1aR2bSi(R3)4−(a+b) Formula (1)and a hydrolyzable silane whose (a+b) is 0 is contained in a proportion of 60 to 85 mol % of a total hydrolyzable silane in Formula (1); the poly hafnium oxide is a hydrolysis-condensation product of hydrolyzable hafnium of Formula (2):Hf(R4)4 Formula (2)and the zirconium oxide is a hydrolysis-condensation product of hydrolyzable zirconium of Formula (3) or Formula (4):Zr(R5)4 Formula (3)ZrO(R6)2 Formula (4)or a hydrolysis-condensation product of a combination thereof.