Immersion Lithography Resist Coating via Alkali Solubility
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In immersion lithography, existing resist protective coatings face challenges such as water solubility, low etch resistance, and the need for specialized solvents for stripping, which hinder effective pattern formation and increase costs.
Innovation Solution
A water-insoluble, alkali-soluble resist protective coating material is developed, comprising a polymer with specific partial structures that allows for simultaneous stripping during alkaline development, enhancing process compatibility and pattern formation precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coating is applied on the resist layer to prevent water contact during immersion lithography, then water solubility problems are solved, but the coating requires specialized stripping solvents and additional process steps
Solution Approach 1:
The protective coating uses a polymer with specific chemical structure (carboxyl groups or sulfonic acid groups) that changes its solubility parameters based on pH. The coating is water-insoluble at neutral pH but becomes soluble in alkaline conditions during development, eliminating the need for specialized stripping solvents and simplifying the process
Solution Approach 2:
The protective coating serves multiple functions: it protects the resist from water during immersion lithography, maintains pattern definition, and can be simultaneously stripped with the resist using the same alkaline developer solution, reducing process steps and complexity
2Object-affected harmful factors
If existing protective coating materials are used, then water repellency is achieved, but etch resistance is low and pattern definition deteriorates
Solution Approach 1:
The protective coating uses a composite polymer structure combining hydrophobic groups (for water repellency) with alkaline-soluble groups like carboxyl or sulfonic acid groups. This composite structure maintains both water repellency during lithography and good etch resistance, while allowing clean removal in alkaline developers
Solution Approach 2:
The polymer structure has different functional groups serving different purposes: hydrophobic portions provide water repellency during exposure, while alkaline-soluble portions (carboxyl or sulfonic acid groups) provide controlled solubility for stripping, creating local quality differentiation within the same material
3Ease of manufacture
If fluorocarbon solvents are used for stripping the protective coating, then complete removal is achieved, but environmental concerns arise and process costs increase
Solution Approach 1:
The protective coating is designed to change its solubility behavior based on pH parameters. By using alkaline developers (pH change) instead of fluorocarbon solvents, the coating can be completely removed efficiently without environmental concerns, maintaining ease of manufacture while eliminating harmful factors
Solution Approach 2:
The protective coating is designed as a temporary, disposable layer that can be easily and completely removed using inexpensive, environmentally friendly alkaline developers, replacing the need for expensive and environmentally problematic fluorocarbon solvents
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 new coating material enables effective pattern formation in immersion lithography by being insoluble in water and dissolvable in alkali solutions, allowing for simultaneous development and stripping, thus improving process efficiency and reducing operational complexity.
Implementation Method 1
a water-insoluble, alkali-soluble resist protective coating material
Implementation Method 2
a water-insoluble, alkali-soluble resist protective coating material comprising a polymer with specific partial structures that allows for simultaneous stripping during alkaline development
Data Source
AI summary
A resist protective coating material is provided comprising a polymer having a partial structure of formula (1) wherein R0 is H, F, alkyl or alkylene, and R1 is fluorinated alkyl or alkylene. In a pattern-forming process, the material forms on a resist film a protective coating which is water-insoluble, dissolvable in alkaline developer and immiscible with the resist film, allowing for effective implementation of immersion lithography. During alkali development, development of the resist film and removal of the protective coating can be simultaneously achieved.