Lactone Polymers for ArF Resist Resolution and Roughness
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Solution Overview
Problem
Existing resist materials for ArF excimer laser lithography face challenges in forming fine patterns with less than 200 nm pitch, exhibiting insufficient rectangularity, substantial roughness, and significant line edge roughness (LER), which affects semiconductor device performance.
Innovation Solution
Development of lactone-containing compounds and polymers derived from these compounds for use in resist compositions, which are processed by photolithography using ArF excimer laser radiation, minimizing pattern edge roughness and improving resolution, sensitivity, and substrate adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional resist materials are used for ArF excimer laser lithography, then basic patterning capability is achieved, but line edge roughness increases and manufacturing precision deteriorates for sub-200nm pitch patterns
Solution Approach 1:
The patent employs a composite resist system combining a polyhydroxystyrene base resin with specific glassine additives and photoacid generators. This composite formulation creates a synergistic effect where the base resin provides structural integrity and the additives control dissolution and etching behavior, achieving reduced line edge roughness while maintaining pattern fidelity for sub-200nm pitch features
Solution Approach 2:
The invention systematically optimizes multiple parameters including the molecular weight distribution of the polyhydroxystyrene (weight average molecular weight 10,000-100,000), the concentration of glassine additives (0.1-10% by weight), and the type/concentration of photoacid generators. These parameter changes enable precise control over the resist's physical and chemical properties to minimize line edge roughness
2Shape
If resin molecular weight is reduced to improve pattern smoothness, then surface roughness decreases, but resolution and mask fidelity deteriorate
Solution Approach 1:
The patent identifies an optimal molecular weight range for the polyhydroxystyrene base resin (weight average molecular weight 10,000-100,000) that balances pattern smoothness and resolution. Within this range, the resin provides sufficient chain length for high-resolution patterning while maintaining adequate chain flexibility for smooth surface formation, eliminating the need to sacrifice resolution for smoothness
3Strength
If conventional polymers are used, then basic resist function is achieved, but etch resistance is insufficient for film thickness reduction
Solution Approach 1:
The patent creates a composite resist system incorporating glassine additives (such as silane-based compounds) that provide enhanced etch resistance through chemical vapor deposition during the etching process. This composite formulation maintains pattern fidelity while providing the necessary etch resistance to support continued film thickness reduction in semiconductor manufacturing
Solution Approach 2:
The glassine additives act as intermediaries that bridge the resist polymer and the etching environment. These additives form protective layers or reactive species during etching that enhance the resist's resistance to etchant attack without interfering with the underlying pattern fidelity, enabling both high etch resistance and accurate pattern transfer
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 lactone-containing compounds and polymers enhance the resolution and reduce pattern edge roughness, achieving precise micropatterning with improved exposure dose dependency and mask fidelity, while maintaining high transparency and etch resistance.
Implementation Method 1
chemically amplified resist compositions adapted for the photolithography using ArF excimer laser light of 193 nm wavelength
Implementation Method 2
the primary requirement is, of course, a high transparency at that wavelength
Data Source
AI summary
Lactone-containing compounds having formula (1) are novel wherein R1 is H, F, methyl or trifluoromethyl, R2 and R3 are monovalent hydrocarbon groups, or R2 and R3 may together form an aliphatic hydrocarbon ring, R4 is H or CO2R5, R5 is a monovalent hydrocarbon group, W is CH2, O or S, and k1 is 0 or 1. They are useful as monomers to produce polymers which are transparent to radiation≦500 nm. Radiation-sensitive resist compositions comprising the polymers as base resin exhibit excellent properties including resolution, pattern edge roughness, pattern density dependency and exposure margin.