Immersion Lithography Topcoat Composition for Leaching Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In immersion lithography, direct contact between the immersion fluid and photoresist layer leads to leaching of photoresist components, causing contamination and affecting the optical properties of the lens, and existing topcoat layers can introduce defects and reduce device yield due to micro-bridging and altered resist sensitivity.
Innovation Solution
A topcoat composition comprising a polymer system with a matrix polymer and a surface active polymer, along with a solvent system, that self-segregates to form a graded layer, reducing photoresist material migration into the immersion fluid and improving water receding contact angles for faster scanning speeds and increased process throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a topcoat layer is used to prevent photoresist leaching, then contamination of the optical lens is reduced, but micro-bridging defects and altered resist profile occur
Solution Approach 1:
The topcoat composition uses a block copolymer with distinct functional blocks: one block provides water receding properties at the immersion fluid interface, while another block provides developer solubility at the photoresist interface. This local differentiation of properties within a single material allows the topcoat to perform multiple functions without compromising resist profile.
Solution Approach 2:
The invention employs a block copolymer composite structure where hydrophobic blocks (e.g., polyisobutylene) and hydrophilic blocks (e.g., polyacrylic acid) are chemically bonded together. This composite structure enables the topcoat to simultaneously repel water and interact with developer solution, resolving the contradiction between preventing leaching and maintaining resist profile integrity.
2Object-affected harmful factors
If topcoat layer thickness is increased to improve barrier properties, then photoresist protection is enhanced, but process window and critical dimension variation worsen
Solution Approach 1:
The topcoat composition is formulated with specific molecular weight ranges (e.g., 10,000-1,000,000 g/mol) and functional group concentrations to achieve optimal barrier properties at minimal thickness. The block copolymer structure provides enhanced barrier performance per unit thickness, allowing thin coatings to effectively prevent leaching without impacting critical dimension control.
3Productivity
If water receding contact angle is increased to improve scan speed, then throughput is increased, but water mark defects may occur
Solution Approach 1:
The block copolymer topcoat maintains continuous water receding action across the entire exposure surface during scanning. The hydrophobic blocks provide sustained water repellency that prevents water droplet formation and subsequent water mark defects, enabling high scan speeds without compromising pattern fidelity.
4Productivity
If topcoat material is optimized for water receding properties, then scan speed increases, but developer solubility may be compromised
Solution Approach 1:
The topcoat polymer is segmented into functionally distinct blocks: hydrophobic segments (e.g., polyisobutylene) provide water receding properties for high scan speed, while hydrophilic segments (e.g., polyacrylic acid with carboxylic acid groups) provide developer solubility. This segmentation allows independent optimization of each property within the same material.
Solution Approach 2:
The block copolymer acts as an intermediary layer between the immersion fluid and photoresist, with its dual-nature structure mediating between water repellency requirements (for high scan speed) and developer interaction requirements (for proper pattern formation). The amphiphilic structure enables simultaneous satisfaction of both requirements.
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 topcoat composition minimizes photoresist material migration into the immersion fluid, enhancing water contact angle characteristics and developer solubility, thereby reducing defects and improving the yield and throughput in semiconductor device manufacturing.
Implementation Method 1
self-segregating topcoat compositions to form a graded topcoat layer
Implementation Method 2
the surface active polymer has a lower surface energy than a surface energy of the matrix polymer
Implementation Method 3
direct contact between the immersion fluid and photoresist layer can result in leaching of components of the photoresist into the immersion fluid
Implementation Method 4
an improved water receding contact angle at the immersion fluid interface
Data Source
AI summary
Topcoat compositions are provided that can be used in immersion lithography to form photoresist patterns. The topcoat compositions include a solvent system that comprises 1) a first organic solvent represented by formula (I),wherein R1 and R2 are alkyl groups of 3-8 carbons and the total number of carbons of R1 and R2 is greater than 6; and2) a second organic solvent that is a C4 to C10 monovalent alcohol.