Photosensitive Resist Underlayer Film Composition for Lithography
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Solution Overview
Problem
Conventional anti-reflective coatings for lithography in semiconductor production are ineffective in preventing photoacid generator elution and do not allow concurrent development with photoresists, leading to issues with pattern shape and dimensional precision, especially with short-wavelength light exposure.
Innovation Solution
A composition for forming a resist underlayer film that includes a polymer with unit structures containing amide linkages, a crosslinkable compound, a photoacid generator, and a solvent, which suppresses photoacid generator elution and enables alkali development, allowing for concurrent removal with the photoresist without dry etching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a conventional thermally crosslinkable anti-reflective coating is used, then intermixing with photoresist is prevented, but the coating requires dry etching for removal which also etches the photoresist, reducing photoresist film thickness and pattern precision
Solution Approach 1:
The patent changes the chemical composition parameters of the anti-reflective coating by incorporating polymers with specific functional groups (carboxyl, hydroxyl, or amine groups) that enable alkali solubility. This allows the coating to be removed by alkali development rather than dry etching, preventing photoresist thickness reduction and maintaining pattern precision while preserving coating stability through controlled solubility characteristics.
Solution Approach 2:
The patent creates a composite anti-reflective coating material combining polymer base structures with specific functional groups (carboxyl, hydroxyl, or amine groups) and crosslinkable compounds. This composite structure provides both the stability needed to prevent intermixing with photoresist and the controlled solubility required for alkali-based removal, eliminating the need for damaging dry etching processes.
2Ease of manufacture
If dry etching is used to remove the anti-reflective coating, then the coating is effectively removed, but the photoresist is also damaged and its film thickness is reduced
Solution Approach 1:
The patent introduces an intermediary chemical mechanism where the anti-reflective coating contains functional groups (carboxyl, hydroxyl, or amine groups) that act as mediators for alkali-based removal. This intermediary chemical property allows selective removal of the coating through alkali development without affecting the photoresist, replacing the mechanical/physical dry etching process with a chemically selective alternative that preserves photoresist integrity.
3Productivity
If the anti-reflective coating is designed to be soluble in alkaline developer, then concurrent development with photoresist is possible, but the coating may elute into the photoresist solvent during application
Solution Approach 1:
The patent applies preliminary crosslinking action to the anti-reflective coating before the development process. The crosslinkable compounds form a stable network structure in advance that prevents elution into the photoresist solvent during application, while the functional groups (carboxyl, hydroxyl, or amine groups) remain available for subsequent alkali-based concurrent development with the photoresist, achieving both stability and productivity.
Solution Approach 2:
The patent provides beforehand cushioning against elution by incorporating crosslinkable compounds that form a protective network structure before the development stage. This pre-formed structure acts as a cushion that prevents the coating material from dissolving into the photoresist solvent during application, while still allowing controlled removal through alkali development after the photoresist is applied and exposed.
4Object-affected harmful factors
If a photoresist pattern with large line width is used for ion implantation, then standing wave effects are reduced, but fine pattern formation is not achieved for modern device structures
Solution Approach 1:
The patent enables fine pattern copying by providing a stable anti-reflective coating underlayer that supports thin photoresist films. The coating's optical properties and structural stability allow high-resolution pattern transfer from the mask through the photoresist without standing wave interference, enabling faithful copying of fine patterns required for modern device structures while maintaining pattern fidelity.
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 effectively absorbs short-wavelength light, prevents intermixing with photoresists, and achieves high-resolution pattern formation with reduced footing, ensuring precise microfabrication.
Implementation Method 1
The composition effectively absorbs short-wavelength light
Implementation Method 2
a photoacid generator
Data Source
AI summary
A composition for forming a resist underlayer film to be used in a lithography process, that includes: a polymer containing unit structures of Formula (1), Formula (2), and Formula (3):the polymer being a polymer in which the unit structure of Formula (1) has a ratio of mole number (a) within a range of 0.20≦a≦0.90, the unit structure of Formula (2) has a ratio of mole number (b) within a range of 0.05≦b≦0.60, and the unit structure of Formula (3) has a ratio of mole number (c) within a range of 0.001≦c≦0.40, when a total mole number of all unit structures constituting the polymer is 1.0, and the polymer having a weight average molecular weight of 3,000 to 100,000; a crosslinkable compound; a photoacid generator; and a solvent.