Positive-Working Resist Composition for ArF Lithography
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Solution Overview
Problem
Existing positive resist compositions with acetal groups as acid-dissociable, dissolution-inhibiting groups face significant fluctuations in pattern size when exposed to varying radiation, leading to inadequate resolution and pattern fidelity, especially when using ArF excimer lasers.
Innovation Solution
A positive resist composition incorporating a polymer compound with specific structural units and an onium salt-based acid generator, which increases alkali solubility upon exposure, reducing pattern size fluctuations by ensuring acid-dissociable groups dissociate effectively, thereby improving resolution and pattern stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If acetal groups are used as acid-dissociable, dissolution-inhibiting groups in positive resist compositions, then the resist can function with ArF excimer laser lithography, but the pattern size fluctuates significantly when exposure varies
Solution Approach 1:
The patent changes the chemical structure parameters of the acid-dissociable groups by introducing specific structural formulas (I) and (II) with defined molecular weights and compositions. These parameter changes optimize the dissociation energy and alkali solubility characteristics, enabling the resist to maintain stable pattern dimensions across varying exposure conditions while remaining compatible with ArF excimer laser lithography.
2Reliability
If strong acid-generating onium salts are used to ensure adequate dissociation of acid-dissociable groups, then the resist functions properly, but the pattern size fluctuation increases under varying exposure
Solution Approach 1:
The patent employs a composite resist composition containing multiple components: polymer compounds with specific structural units (I) and (II), onium salt-based acid generators, and various additives. This composite formulation creates synergistic effects where the polymer structure compensates for the strong acid generation, maintaining both resist functionality and pattern size stability through the combined properties of its constituents.
3Stability of the object's composition
If the acid-dissociable groups have high dissociation energy, then the resist structure remains stable, but the groups do not dissociate satisfactorily without strong acid generators
Solution Approach 1:
The patent optimizes the dissociation energy parameter of the acid-dissociable groups by introducing specific structural formulas with controlled molecular weights (5,000-50,000) and compositional ratios (structural unit I: structural unit II at 70:30 to 30:70). These parameter adjustments enable satisfactory dissociation with onium salt-based acid generators while maintaining structural stability throughout the exposure and development process.
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 reduced pattern size fluctuations and enhanced resolution, maintaining pattern fidelity even under varying exposure conditions, with improved adhesion and hydrophilicity, suppressing pattern collapse and footing.
Implementation Method 1
an acid generator component (B) that generates acid on exposure to radiation
Data Source
AI summary
The present invention is a positive resist composition and a resist pattern forming method including a resin component (A) which has a polymer compound (A1) having a structural units (a1) including an acetal type acid dissociable, dissolution inhibiting group, a structural unit (a2) derived from an acrylate ester having a lactone-containing polycyclic group, and a structural unit (a3) derived from an acrylate ester having a polar group-containing aliphatic hydrocarbon group, and an acid generator component (B) having an onium salt-based acid generator (B1) having a cation portion represented by a general formula (b-1) shown below [wherein, R11 represents an alkyl group, an alkoxy group, a halogen atom or a hydroxyl group; R12 to R13 each represents, independently, an aryl group or the alkyl group that may have substituent group; n' represents either 0 or an integer from 1 to 3].