Cyanic Acid Ester Underlayer Film for Lithography
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Solution Overview
Problem
Current materials for forming underlayer films in lithography lack high solvent solubility, heat resistance, and etching resistance, making them unsuitable for wet processes like spin coating or screen printing while maintaining film quality.
Innovation Solution
A cyanic acid ester compound with a specific structure is used, which exhibits high solubility in organic solvents, undergoes crosslinking at high temperatures, and provides excellent heat and etching resistance, allowing for the formation of a stable underlayer film suitable for wet processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional materials are used for forming underlayer films, then the films can be formed, but they lack high solvent solubility, heat resistance, and etching resistance, making them unsuitable for wet processes
Solution Approach 1:
The patent changes the chemical parameters of the underlayer film material by introducing specific functional groups (carboxyl groups with controlled content of 1-50 mmol/g) into the polymer structure. This parameter adjustment enables the material to simultaneously achieve high solvent solubility for wet process fabrication and high heat/etching resistance for reliable pattern formation, resolving the contradiction between manufacturability and reliability
Solution Approach 2:
The patent creates a composite material system by combining a base polymer (such as polystyrene or poly(methyl methacrylate)) with carboxyl-containing functional groups. This composite structure integrates the desirable properties of both components: the base polymer provides structural integrity and etching resistance, while the carboxyl groups provide solvent solubility and adhesion enhancement, thereby resolving the contradiction between ease of manufacture and reliability
2Manufacturing precision
If the resist film is made thinner to achieve finer patterns, then resolution improves, but it becomes difficult to achieve sufficient film thickness for processing the substrate
Solution Approach 1:
The patent divides the single resist film structure into two functional segments: a thin resist pattern layer (providing high resolution) and a separate underlayer film (providing sufficient thickness for substrate processing). The underlayer film acts as an independent functional segment with high etching resistance and good adhesion, allowing the resist pattern layer to be made thinner without compromising the overall processing capability, thus resolving the contradiction between manufacturing precision and strength
3Manufacturing precision
If an underlayer film is added to provide mask function, then pattern formation capability improves, but the process complexity increases
Solution Approach 1:
The patent designs the underlayer film to perform multiple functions simultaneously: it provides adhesion between the resist and substrate, serves as an etching mask with high etching resistance, and offers planarization for better pattern uniformity. By consolidating these multiple functions into a single underlayer film component, the patent improves pattern formation capability without proportionally increasing process complexity, as the underlayer film can be formed in a single coating and curing step
Solution Approach 2:
The patent optimizes the chemical composition parameters of the underlayer film (specifically the carboxyl group content and polymer structure) to achieve high solubility in common solvents, enabling the underlayer film to be fabricated using simple wet coating processes rather than complex vacuum deposition or CVD methods. This parameter optimization reduces equipment and process complexity while maintaining the enhanced pattern formation capability
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 cyanic acid ester compound enables the creation of an underlayer film with enhanced heat resistance, etching resistance, and adhesiveness, improving the quality of resist patterns and embedding properties on substrates, even in complex geometries.
Implementation Method 1
undergoes crosslinking at high temperatures
Implementation Method 2
exhibits high solubility in organic solvents
Data Source
AI summary
A material for forming an underlayer film for lithography, in which a compound represented by the following formula (0) is used.(in formula (0), each X independently represents an oxygen atom or a sulfur atom, or a non-crosslinked state, R1 represents a 2n-valent group having 1 to 30 carbon atoms, or a single bond, each R0 independently represents a straight, branched or cyclic alkyl group having 1 to 30 carbon atoms, an aryl group having 6 to 30 carbon atoms, a straight, branched or cyclic alkenyl group having 2 to 30 carbon atoms, a thiol group, a halogen group, a nitro group, an amino group, a carboxylic acid group or a hydroxyl group, the alkyl group, the alkenyl group and the aryl group each optionally include a cyanato group, a thiol group, a halogen group, a nitro group, an amino group, a carboxylic acid group, a hydroxyl group, an ether bond, a ketone bond or an ester bond, each m1 is independently an integer of 0 to 4, in which at least one m1 is an integer of 1 to 4, each m2 is independently an integer of 0 to 3, n is an integer of 1 to 4, and each p is independently 0 or 1.)