Cycloolefin Underlayer for Lithographic Etch Resistance
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Solution Overview
Problem
Chemically amplified resist systems in semiconductor manufacturing face challenges such as standing wave effects, substrate poisoning, and the need for high plasma etch resistance, which are difficult to achieve simultaneously due to tradeoffs in material properties like absorbance, etch resistance, and refractive index matching between layers.
Innovation Solution
A thermally curable polymer composition using cycloolefin polymers with aromatic pendant groups is developed, providing tunable absorbance and excellent etch resistance, and is formulated with cycloolefin repeating units, amino or phenolic cross-linking agents, thermal acid generators, and solvents to create an Underlayer film that minimizes reflective interference and enhances plasma etch resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If chemically amplified resist systems are used to achieve high sensitivity and resolution, then lithographic performance is improved, but plasma etch resistance deteriorates
Solution Approach 1:
The patent divides the resist system into two separate layers: a chemically amplified imaging layer for high-resolution patterning and a separate underlayer for plasma etch resistance. This segmentation allows each layer to be optimized for its specific function without compromise.
Solution Approach 2:
The patent employs composite material structures combining different polymer systems - the imaging layer uses chemically amplified resists while the underlayer uses etch-resistant materials, creating a multi-layer composite that achieves both high resolution and plasma etch resistance simultaneously.
2Manufacturing precision
If photoresist film thickness is reduced to minimize standing wave effects, then line width control is improved, but etch resistance deteriorates
Solution Approach 1:
The patent segments the protective function against standing waves from the etch resistance function by placing an underlayer between the substrate and the thin photoresist film. This allows the photoresist to be kept thin for better line width control while the underlayer provides the necessary etch resistance.
Solution Approach 2:
The underlayer acts as an intermediary layer that mediates between the thin photoresist film and the substrate, providing etch resistance and reducing standing wave effects without requiring the photoresist itself to be thick.
3Illumination intensity
If aromatic groups are removed from chemically amplified photoresists to decrease absorbance, then lithographic transparency is improved, but etch resistance deteriorates
Solution Approach 1:
The patent separates the optical properties from the etch resistance properties by placing aromatic-containing etch-resistant materials in the underlayer while keeping the imaging layer free of aromatic groups for optimal lithographic transparency.
Solution Approach 2:
The patent creates a composite structure where the underlayer contains aromatic groups for etch resistance while the imaging layer uses non-aromatic chemically amplified materials for transparency, combining the benefits of both material types in a multi-layer system.
4Quantity of substance
If anti-reflective coatings are made thinner to retain sufficient photoresist thickness, then photoresist film integrity is improved, but absorbance decreases
Solution Approach 1:
The underlayer serves as an intermediary that provides anti-reflective functionality without requiring a thick ARC layer, allowing sufficient photoresist thickness to be maintained while achieving the necessary absorbance through the combined underlayer-ARC structure.
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 solution achieves high etch resistance and tunable absorbance, improving lithographic performance by reducing line width variations and maintaining compatibility with edge bead remover solvents, while allowing for efficient pattern transfer into substrates with enhanced dimensional stability.
Implementation Method 1
a thermal acid generator
Implementation Method 2
an acid generated by photolysis catalyzes a solubility switch from alkali insoluble to alkali soluble by removal of an acid sensitive (acid cleavable) group
Implementation Method 3
requirements of sensitivity, transparency, aesthetics of the image produced, and the selectivity of the resists to etch conditions for pattern transfer become more and more strenuous
Implementation Method 4
lithographic aspect ratios require the chemically amplified resist layer be thin, e.g., about 500 nm or lower, to print sub 180 nm features. This in turn requires the resist to have excellent plasma etch resistance
Data Source
AI summary
An etch resistant thermally curable Underlayer for use in a multiplayer liyhographic process to produce a photolithographic bilayer coated substrate, the composition having:(a) at least one cycloolefin polymer comprising at least one repeating unit of Structure (I), and at least one repeating unit of Structure (II), and optionally at least one repeating unit of Structure (III) with the proviso that neither Structure (I) nor Structure (II) nor Structure (III) contains acid sensitive groups.b) at least one cross-linking agent selected from the group consisting of an amino or phenolic cross-linking agent;c) a least one thermal acid generator (TAG);d) at lest one solvent; ande) optionally, at least one surfactant.