Antireflective Coating Composition for 193 nm Photoresist
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Solution Overview
Problem
In photolithographic processes, highly reflective substrates cause back reflection issues such as thin film interference and reflective notching, leading to line width variations and photoresist loss, especially at lower wavelengths like 193 nm, where existing antireflective coatings fail to provide sufficient etch rates and absorption characteristics.
Innovation Solution
A novel antireflective coating composition comprising a polyester polymer with specific chemical structures, a crosslinking agent, and an acid generator, which forms a thin film with high etch rates and absorption properties, minimizing intermixing with the photoresist and preventing line width variations, particularly effective at 193 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If conventional antireflective coatings are used to reduce back reflection, then reflective notching and thin film interference are diminished, but etch rate becomes insufficient and photoresist loss increases
Solution Approach 1:
The patent modifies the chemical composition parameters of the antireflective coating by incorporating specific polyester polymers with controlled molecular weights and functional groups. This changes the etch selectivity parameters between the antireflective coating and photoresist, enabling sufficient etch rate while maintaining optical absorption properties to prevent reflective notching and thin film interference.
Solution Approach 2:
The patent creates a composite antireflective coating system consisting of polyester polymer, crosslinking agent, and acid generator. This composite material provides multiple functions simultaneously: optical absorption to prevent interference effects, controlled etch rate through plasma reactions, and adhesion to the substrate. The synergistic combination resolves the contradiction between preventing reflective defects and enabling sufficient etching.
2Manufacturing precision
If bottom antireflective coating is applied to eliminate reflectivity, then line width variations are reduced, but intermixing between coating and photoresist occurs
Solution Approach 1:
The patent applies local quality by creating distinct chemical zones: the antireflective coating contains polyester polymer with specific functional groups that provide optical absorption and etch resistance, while the photoresist layer maintains its own chemical composition for patterning. The crosslinking agent creates a localized barrier at the interface that prevents intermixing while allowing clean plasma etching of the antireflective coating. This localized chemical differentiation maintains composition stability and prevents unwanted mixing.
3Object-affected harmful factors
If highly absorbing antireflective coating is used to prevent back reflection, then reflective notching is reduced, but film thickness control becomes difficult
Solution Approach 1:
The patent optimizes the optical parameters of the antireflective coating by adjusting the polyester polymer composition, molecular weight, and concentration of absorbing groups. This enables achieving the required optical absorption (high k value) with thinner film deposits, improving thickness uniformity and control while maintaining effectiveness against reflective notching and back reflection.
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 ensures minimal loss of the photoresist layer during etching, achieves clean images with good lithographic properties, and maintains the purity of semiconductor devices by forming thin, effective films with optimized optical characteristics.
Implementation Method 1
The coated substrate is then subjected to an image-wise exposure to radiation. This radiation exposure causes a chemical transformation in the exposed areas of the coated surface.
Implementation Method 2
The antireflective coating in the exposed area is then etched, typically in gaseous plasma, and the photoresist pattern is thus transferred to the substrate.
Data Source
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AI summary
The invention relates to an antireflective coating composition for a photoresist layer comprising a polymer, a crosslinking agent and an acid generator, where the polymer comprises at least one unit of structure 1, (Formula I) (I) where, X is a linking moiety selected from a nonaromatic (A) moiety, aromatic (P) moiety and mixture thereof, R' is a group of structure (2), R" is independently selected from hydrogen, a moiety of structure (2), Z and W-OH, where Z is a (Cr C20) hydrocarbyl moiety and W is a (C1-C20) hydrocarbylene linking moiety, and, Y' is independently a (C1-C20) hydrocarbylene linking moiety, where structure (2) is (Formula II) (II) where R1 and R2 are independently selected from H and C1C4alkyl and L is an organic hydrocarbyl group. The invention further relates to a process for imaging the antireflective coating composition.