Alkali-Soluble Resist Protective Coating for Immersion Lithography
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Solution Overview
Problem
Current photolithography techniques face challenges with the use of water in immersion lithography, leading to pattern collapse and sensitivity changes due to acid dissolution and evaporation, and existing resist protective coatings are not adequately hydrophobic or alkali-developable, requiring additional processing steps and environmental concerns.
Innovation Solution
A water-insoluble, alkali-soluble resist protective coating material is developed, comprising specific polymer structures that can be simultaneously stripped during alkaline development, maintaining pattern integrity and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective coating is applied to prevent acid dissolution in water, then pattern stability is improved, but additional processing steps are required and the coating must be removable
Solution Approach 1:
The patent combines the protective coating material and the resist material into a single dual-functional composition. The coating forms in situ on the resist surface during application, eliminating the need for separate coating and stripping processes while maintaining pattern stability during immersion lithography.
Solution Approach 2:
The resist protective coating material serves multiple functions: it acts as both a protective barrier against acid dissolution during immersion lithography and a removable layer after exposure. The material is designed to be water-insoluble for protection but soluble in alkali developers for easy removal, combining protective and removable functionalities in one material.
2Reliability
If existing protective coatings are used, then some protection is provided, but they require additional stripping steps and have environmental concerns
Solution Approach 1:
The patent extracts the protective function from a separate coating material and integrates it into the resist composition itself. This eliminates the need for additional protective coating materials and their associated application and stripping processes, simplifying the overall manufacturing process.
Solution Approach 2:
The resist composition automatically forms a protective coating on its own surface during the application process. The coating material is incorporated into the resist and self-assembles or precipitates on the resist surface, eliminating the need for separate coating application equipment and processes.
3Reliability
If the protective coating is made water-insoluble to prevent dissolution, then pattern stability is improved, but the coating must also be easily removable by alkali developers
Solution Approach 1:
The patent utilizes changes in chemical solubility parameters based on pH. The protective coating material is designed to be insoluble in water (neutral pH) for protection during immersion lithography, but soluble in alkali developers (high pH) for easy removal. This parameter change allows the same material to exhibit opposite solubility behaviors under different chemical conditions.
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, improves process compatibility, and maintains resist stability, reducing defects and environmental impact.
Implementation Method 1
The resist protective coating material is developed, comprising specific polymer structures that can be simultaneously stripped during alkaline development, maintaining pattern integrity and stability
Implementation Method 2
A water-insoluble, alkali-soluble resist protective coating material is developed, comprising specific polymer structures that can be simultaneously stripped during alkaline development
Data Source
AI summary
A polymer comprising repeat units having formula (1) wherein R1 and R2 are hydrogen or C1-C12 alkyl, or R1 and R2 may bond together to form a ring, and R30 is hydrogen or methyl is used to formulate a resist protective coating material. A protective coating formed therefrom on a resist film is water-insoluble, dissolvable in alkali aqueous solution or alkaline developer, and immiscible with the resist film so that the immersion lithography can be conducted in a satisfactory manner. During alkali development, development of the resist film and removal of the protective coating can be simultaneously achieved.