Antireflective Coating Composition for Microlithography
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Solution Overview
Problem
In microlithography, the miniaturization of semiconductor devices leads to challenges such as thin film interference and reflective notching due to back reflection from highly reflective substrates, which affect the uniformity and resolution of photoresist patterns, necessitating the use of advanced antireflective coatings that provide sufficient dry etch resistance and prevent intermixing with photoresists.
Innovation Solution
A novel organic spin coatable antireflective coating composition with high carbon content, comprising a polymer with a fused aromatic ring, hydroxylbiphenyl, and derivatized fluorene units, which can crosslink to form a hard mask layer that reduces reflections and enhances pattern transfer while maintaining solubility and coating uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional antireflective coatings are used, then back reflection is reduced, but dry etch resistance is insufficient and intermixing with photoresist occurs
Solution Approach 1:
The patent uses a composite material system consisting of an inorganic silicon layer combined with an organic polymer coating. The silicon layer provides the primary antireflective function and etch resistance, while the organic polymer layer enhances adhesion, provides additional etch resistance, and prevents intermixing with the photoresist. This composite structure resolves the contradiction by combining the advantages of both materials to achieve both optical performance and chemical resistance.
Solution Approach 2:
The patent modifies the chemical and physical parameters of the coating material by using a specific organic polymer composition with controlled molecular weight, functionality, and purity. The polymer is designed to crosslink upon exposure to radiation, changing its state from soluble to insoluble, thereby providing hard mask properties and preventing intermixing while maintaining the antireflective function of the underlying silicon layer.
2Manufacturing precision
If the photoresist layer is made thinner for miniaturization, then resolution is improved, but thin film interference and reflective notching increase
Solution Approach 1:
The patent introduces an intermediary antireflective coating layer (the silicon layer with organic polymer coating) between the photoresist and the substrate. This intermediary layer absorbs reflected light and prevents it from interfering with the photoresist patterning process. By placing this absorbing layer in the optical path, the harmful thin film interference effects are eliminated, allowing thinner photoresist layers to be used for miniaturization without sacrificing pattern uniformity.
3Manufacturing precision
If a thick organic mask layer is used for high aspect ratio, then etch masking is improved, but coating uniformity and solubility decrease
Solution Approach 1:
The patent carefully controls the parameters of the organic polymer coating, including molecular weight, functionality, and concentration, to achieve optimal performance. The polymer is designed to crosslink upon radiation exposure, which allows the use of thicker films for high aspect ratio etch masking while maintaining coating uniformity and solubility during the coating process. The crosslinking transformation occurs after coating, preserving the stability and uniformity achieved during application.
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 antireflective coating composition enables high-resolution image transfer with high aspect ratios, reduces reflections, and improves pattern transfer, maintaining stability and etch resistance, thus addressing the challenges of miniaturization in microlithography.
Implementation Method 1
a polymer capable of crosslinking... The polymer is crosslinked upon exposure to radiation
Implementation Method 2
Absorbing antireflective coatings... An antireflective coating coated beneath a photoresist and above a reflective substrate provides significant improvement in lithographic performance
Data Source
AI summary
The present invention relates to an absorbing hard mask antireflective coating composition comprising a novel polymer, where the novel polymer comprises in the backbone of the polymer four repeat units -A-, -B-, -C- and -D-, where A is repeat unit which comprises a fused aromatic ring in its backbone, B has the structure (1), C is a hydroxylbiphenyl of structure (2) and D is a derivatized fluorene of structure (3),where R1 is C1-C4alkyl, R2 is C1-C4alkyl, R3 and R4 are independently hydrogen or C1-C4 alkyl, and Ar′ and Ar″ are independently phenylenic, or naphthalenic derived moieties, R5 and R6 are independently —OH or —(CH2)nOH where n=2-4, and R7 and R8 are independently hydrogen or C1-C4 alkyl. This invention also relates to a process for forming an image using the novel antireflective coating composition.