Bottom Resist Layer Composition for Lithography
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Solution Overview
Problem
Current bottom resist layer compositions for multilayer-resist processes in semiconductor manufacturing face challenges in achieving optimal refractive indices and etching resistance, particularly when used with shorter wavelengths and silicon-containing intermediate layers, leading to issues with pattern accuracy and antireflection effects.
Innovation Solution
A bottom resist layer composition comprising a polymer with a specific repeating unit, such as a nortricyclen derivative, is developed, which provides optimal refractive indices and etching resistance, suitable for bilayer and trilayer resist processes, especially when used with silicon-containing intermediate layers, and includes optional additives like organic solvents, acid generators, and crosslinkers to enhance application properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional bottom resist layer compositions are used, then the process is simple and well-established, but the refractive index cannot be optimized and etching resistance is insufficient for shorter wavelengths and silicon-containing intermediate layers
Solution Approach 1:
The patent employs composite polymer materials combining polyhydroxystyrene (for etching resistance and antireflection) with polyacrylonitrile or polymethacrylonitrile (for refractive index control). This composite approach enables simultaneous optimization of multiple optical and chemical properties that cannot be achieved with single polymers, directly resolving the contradiction between manufacturing precision and composition complexity.
Solution Approach 2:
The patent systematically varies composition parameters including polymer ratios (polyhydroxystyrene:polyacrylonitrile = 95:5 to 70:30), molecular weights, and additive concentrations to optimize refractive index and etching resistance. By controlling these parameters, the invention achieves tailored optical properties for specific wavelength ranges while maintaining patterning accuracy.
2Productivity
If the bottom resist layer thickness is reduced, then the overall process efficiency improves and fewer materials are used, but the antireflection effect deteriorates
Solution Approach 1:
The patent optimizes the thickness parameter of the bottom resist layer within the range of 50-200 nm, combined with specific refractive index values (k ≤ 0.3) achieved through the composite polymer formulation. This parameter optimization enables effective antireflection with reduced thickness, improving process efficiency while maintaining manufacturing precision.
Solution Approach 2:
The composite polymer system enhances the specific surface area and optical interaction efficiency per unit thickness, allowing the bottom resist layer to achieve adequate antireflection effect with thinner films. The synergistic combination of polymers maximizes the functional performance relative to the material quantity used.
3Strength
If polyhydroxystyrene is used as the base resin, then etching resistance is improved, but the refractive index becomes too high for optimal antireflection
Solution Approach 1:
The patent creates a composite system where polyhydroxystyrene (providing etching resistance) is combined with polyacrylonitrile or polymethacrylonitrile (providing refractive index control). The synergistic effect of these polymers achieves both high etching resistance and optimized refractive index, resolving the contradiction between strength and manufacturing precision.
Solution Approach 2:
The invention applies different functional properties to different components of the composite: polyhydroxystyrene contributes primarily to etching resistance, while polyacrylonitrile/polymethacrylonitrile contributes to refractive index control. This local quality assignment enables each polymer to excel at its specific function while working together as a unified system.
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 achieves accurate patterning and improved antireflection effects by maintaining optimal refractive indices and etching resistance, even with thinner layers, thereby enhancing the precision and reliability of multilayer-resist processes in semiconductor manufacturing.
Implementation Method 1
lithography using ArF excimer laser (193 nm) has been particularly examined... exhibits optimum n value and k value on exposure to shorter wavelengths... optimal refractive indices
Implementation Method 2
excellent etching resistance under conditions of etching substrates... improved antireflection effects by maintaining optimal refractive indices and etching resistance
Data Source
AI summary
There is disclosed a bottom resist layer composition for a multilayer-resist film used in lithography comprising, at least, a polymer comprising a repeating unit represented by the following general formula (1). Thereby, there can be provided a bottom resist layer composition that exhibits optimum n value and k value on exposure to shorter wavelengths, excellent etching resistance under conditions for etching substrates, and is promising for forming a bottom resist layer used for a multilayer-resist process such as a silicon-containing bilayer resist process or a trilayer resist process using a silicon-containing intermediate resist layer.