Antireflective Coating Composition for Lithography
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Solution Overview
Problem
In microlithography, existing antireflective coatings fail to adequately address issues of thin film interference and reflective notching, particularly in highly reflective substrates with topographical features, leading to line width variations and photoresist loss, and require additional layers for improved etch resistance and aspect ratio.
Innovation Solution
A novel high carbon content antireflective coating composition, comprising a crosslinkable polymer with specific repeat units, is used as a spinable carbon hard mask to reduce reflections and enhance pattern transfer, while maintaining high aspect ratio and plasma etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional antireflective coatings are used on highly reflective substrates, then coating simplicity is maintained, but thin film interference and reflective notching occur causing line width variations and photoresist loss
Solution Approach 1:
The coating system is segmented into multiple functional layers: a bottom antireflective coating layer (BARC) and a top hard mask layer. The BARC layer addresses thin film interference and reflections, while the hard mask layer provides etch resistance and maintains structural integrity during patterning, thereby improving line width control without requiring complete redesign of the entire coating system
Solution Approach 2:
The invention uses composite material structure combining organic BARC material with carbon-rich hard mask material. This composite approach allows each layer to perform its specialized function - the BARC layer reduces reflections and interference, while the hard mask layer provides mechanical strength and etch resistance, collectively solving the line width control problem
2Reliability
If additional hard mask layers are added to improve etch resistance and aspect ratio, then plasma etch resistance is improved, but coating complexity and processing steps increase
Solution Approach 1:
The top hard mask layer is designed to perform multiple functions simultaneously: it provides plasma etch resistance during substrate patterning, maintains high aspect ratio structures, and serves as a protective layer during subsequent processing steps. This multi-functionality reduces the need for additional specialized layers, thereby improving reliability without proportionally increasing coating complexity
3Manufacturing precision
If high carbon content material is used for antireflective coating, then reflections are reduced and pattern transfer is enhanced, but solubility and coating uniformity may be compromised
Solution Approach 1:
The chemical composition parameters of the hard mask material are optimized to achieve the desired balance. The material contains high carbon content (typically 70-90% by weight) for excellent antireflective properties and pattern transfer, while incorporating specific functional groups and molecular structures that maintain adequate solubility in coating solvents and ensure uniform film formation during spin coating processes
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 novel coating composition provides improved solubility, coating uniformity, and via filling capabilities, with high carbon content and low weight loss, enabling effective image transfer and reducing undesirable reflections, thereby enhancing lithographic performance.
Implementation Method 1
The polymer is crosslinked to be insoluble in the solvent of a material to be coated above the polymer
Implementation Method 2
Absorbing antireflective coatings and underlayers in photolithography are used to diminish problems that result from back reflection of light from highly reflective substrates
Implementation Method 3
The present invention relates to a novel organic spin coatable antireflective coating composition
Data Source
Figure 1
AI summary
The present invention relates to a novel absorbing antireflective coating composition comprising a novel crosslinkable polymer comprising at least one repeat unit (A) having structure (1), at least one repeat unit (B) having a structure (2), and at least one repeat unit (C) having structure (3) where D is a direct valence bound or C(R1)(R2) methylene moiety where R1 and R2 are independently H, C1-C8 alkyl, C3-C24 cycloalkyl or C6-C24 aryl; Ari, Arii, Ariii and Ariv are independently phenylenic and naphthalenic moiety, R3 and R4 are independently hydrogen or C1-C8 alkyl; and R5 and R6 are independently hydrogen or C1-C8 alkyl; and a solvent. The invention also relates to a process for forming an image using the novel antireflective coating composition.