Photoresist Underlayer Compositions for Planarization and Thermal Stability
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Solution Overview
Problem
Current photoresist underlayer compositions for electronic device manufacturing face challenges such as pattern collapse due to surface tension, high cost of ownership, inability to form planarizing layers over topography, and limited thermal stability, especially when using chemical vapor deposited carbon materials.
Innovation Solution
Development of a curable compound with a specific formula comprising aromatic rings and solvents, which forms a photoresist underlayer that can be thermally set upon heating, providing improved thermal stability, planarization, and gap-filling capabilities, while being soluble in common solvents and compatible with existing silicon hardmask and antireflective layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical vapor deposited carbon materials are used for underlayer formation, then etch selectivity and antireflective properties are improved, but cost of ownership increases and ability to form planarizing layers over topography is lost
Solution Approach 1:
The patent changes the material parameters by using solution-processed high-carbon content polymers instead of CVD carbon, and further optimizes by incorporating specific aromatic core structures with multiple substituents of formula (1). This parameter change maintains high carbon content for etch selectivity while enabling solution processing for cost reduction and planarization capability.
Solution Approach 2:
The patent creates a composite material system combining aromatic core structures with specific substituent groups (formula (1)) that provide multiple functions: high carbon content for etch resistance, aromatic rings for thermal stability, and appropriate molecular weight for planarization. This composite approach integrates multiple desired properties into a single material system.
2Reliability
If chemical vapor deposited carbon materials are used for underlayer formation, then antireflective properties are improved, but inability to form planarizing layers over topography occurs
Solution Approach 1:
The patent changes the physical state and processing parameters by using solution-processed materials instead of CVD deposition. The solution process allows the material to flow and conform to substrate topography, providing planarization capability while maintaining antireflective properties through high carbon content and appropriate optical parameters (n and k values).
Solution Approach 2:
The patent utilizes the fluid properties of solution-processed materials to achieve planarization. The liquid solution flows into and fills substrate features during spin-coating, and the material's viscosity and surface tension characteristics enable it to conform to and planarize the substrate topography before curing.
3Ease of operation
If materials of relatively low molecular weight are used, then viscosity is reduced and ability to flow into substrate features is improved, but thermal stability at higher cure temperatures deteriorates
Solution Approach 1:
The patent creates a composite molecular structure combining low molecular weight aromatic compounds with multiple high-carbon-content substituents. This structure provides appropriate viscosity for flow into substrate features while the aromatic cores and high carbon content groups contribute to thermal stability during curing and subsequent processing up to 400°C.
Solution Approach 2:
The patent optimizes the molecular weight and structural parameters of the curable compound to achieve a balance between processability and thermal stability. The specific formula (1) with aromatic cores and multiple substituents provides the right combination of molecular weight for flow capability and chemical structure for thermal resistance.
Data Source
AI summary
Photoresist underlayer compositions, comprising: a curable compound comprising a group of the following formula (1):wherein: R1 is each independently H, C1-30 alkyl, or C3-30 cycloalkyl; Ar1 is an aromatic ring or a fused aromatic ring system having from 5 to 30 carbon atoms, wherein Ar1 is substituted or unsubstituted; Ar2 is an aromatic ring chosen from a 6-membered carbocyclic aromatic ring, a 5- or 6-membered heteroaromatic ring, or a fused aromatic ring system having from 5 to 30 carbon atoms, wherein Ar2 optionally comprises a fused cyclic imide moiety, a fused oxazole moiety, a fused imidazole moiety, or a fused thiazole moiety, and wherein Ar2 is substituted or unsubstituted; Y1 is a single covalent bond, or is selected from —O—, —C(O)—, —C(O)O—, —S—, —S(O)2—, —N(R2)—, —C(O)N(R2)—, —C(O)N(R2)C(O)—, —(CH2)y—, or a combination thereof, wherein R2 is H, C1-10 alkyl, C2-10 unsaturated hydrocarbyl, C5-30 aryl, C(O)R3, or S(O)2R3, wherein R3 is chosen from H, C1-10 alkyl, C2-10 unsaturated hydrocarbyl, and C5-30 aryl, and y is an integer from 1 to 6; x is an integer from 2 to 5; and * denotes a binding site to a part of the curable compound other than the group represented by formula (1), provided that no twogroups are in an ortho position to each other on Ar1, wherein ** denotes the point of attachment to an aromatic ring carbon of Ar1; anda solvent.