Resist Underlayer Film Composition for Defect-Free EUV Patterning
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Solution Overview
Problem
Forming a defect-free uniform resist underlayer film with a thickness of 20 nm or less is challenging due to issues like pinholes and roughness in lithography, especially with EUV exposure, where conventional materials and coatings fail to prevent intermixing and ensure desired dry etching rates.
Innovation Solution
A resist underlayer film forming composition comprising a polymer with a specific terminal structure, a cross-linking agent, and a compound promoting cross-linking reactions, along with an organic solvent, is applied to a semiconductor substrate, baked, and exposed to radiation, enabling the formation of a defect-free uniform film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a thin resist underlayer film (20 nm or less) is formed using conventional materials, then the film thickness is reduced to enable finer patterning, but pinholes and aggregations occur making it difficult to form a defect-free uniform film
Solution Approach 1:
The patent modifies the chemical structure parameters of the polymer by introducing specific terminal groups (formula 1) with adjustable R1, R2, R3 substituents and m, n values. This structural parameter change improves coating properties and enables defect-free thin film formation while maintaining the required thickness of 20 nm or less
Solution Approach 2:
The patent creates a composite polymer structure combining a main chain with specific terminal groups (formula 1). This composite structure integrates the light-absorbing functionality of the main chain with the coating-improving properties of the terminal groups, achieving both thin film formation and defect-free uniformity
2Stability of the object's composition
If a resist underlayer film is formed to prevent intermixing with the resist film, then insolubility in resist solvent is achieved, but the film may become too resistant to dry etching or require excessive etching time
Solution Approach 1:
The patent applies local quality by making different parts of the polymer molecule have different properties: the main chain provides light absorption and insolubility for pattern definition, while the terminal groups (formula 1) provide controlled reactivity and etching characteristics. This local differentiation allows the film to be insoluble in resist solvent yet maintain appropriate dry etching rate
3Ease of manufacture
If a polymer with light-absorbing moiety is used for anti-reflective coating, then easy availability and optical properties are achieved, but intermixing with the resist film may occur or desired dry etching rate may not be obtained
Solution Approach 1:
The patent segments the polymer into distinct functional regions: the main chain containing light-absorbing moieties for optical properties, and terminal groups (formula 1) for controlling chemical stability and etching behavior. This segmentation allows each part to independently fulfill its function, preventing intermixing while maintaining optical properties
Solution Approach 2:
The terminal groups (formula 1) act as intermediaries between the light-absorbing main chain and the resist film/etching environment. These terminal groups provide a chemical buffer that prevents direct interaction (intermixing) between the resist and underlayer while maintaining the required dry etching characteristics
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 improves coating properties and enables the formation of a defect-free uniform resist underlayer film, enhancing the formation of desired resist patterns with improved dry etching rates and preventing intermixing with the resist film.
Implementation Method 1
a cross-linking agent; a compound that promotes a cross-linking reaction
Implementation Method 2
exposed to radiation selected from the group consisting of a KrF excimer laser, an ArF excimer laser, extreme ultraviolet rays (EUV), and electron beams
Implementation Method 3
exposed to radiation selected from the group consisting of a KrF excimer laser, an ArF excimer laser, extreme ultraviolet rays (EUV), and electron beams
Data Source
AI summary
A resist underlayer film forming composition for lithography, includes: a polymer including a structure of formula (1) below at a terminal of a polymer chain; a cross-linking agent; a compound that promotes a cross-linking reaction; and an organic solvent:(where R1, R2, and R3 are each independently a hydrogen atom, a linear or branched hydrocarbon group having a carbon atom number of 1 to 13, or a hydroxy group; at least one of R1, R2, and R3 is the hydrocarbon group; m and n are each independently 0 or 1; and a main chain of the polymer is bonded to a methylene group when n is 1 and bonded to a group represented by —O— when n is 0).