Fluorine-Containing Polymer for Liquid Immersion Lithography
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Solution Overview
Problem
Current liquid immersion lithography techniques face challenges in achieving high resolution and depth of focus while minimizing component elution and watermarks, particularly due to insufficient receding contact angles and acid generator elution in resists used for subquarter micron microfabrication.
Innovation Solution
A fluorine-containing polymer with specific molecular weight and structural units is integrated into a radiation-sensitive resin composition, enhancing the receding contact angle with water and reducing component elution, thereby improving pattern shape and depth of focus in liquid immersion lithography.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional resists are used in liquid immersion lithography, then exposure can proceed, but the receding contact angle is insufficient causing watermarks and component elution
Solution Approach 1:
The patent modifies the chemical composition parameters of the resist by incorporating fluorine-containing polymers with specific molecular weights (1,000-100,000) and fluorine content (5-50 wt%). This changes the surface properties of the resist film to achieve a receding contact angle of 60° or more with water, preventing watermarks and component elution during liquid immersion lithography exposure.
Solution Approach 2:
The patent creates a composite resist system by combining fluorine-containing polymers (which provide high receding contact angle) with acid-generating compounds and other resist components. The fluorine-containing polymer acts as a surface-modifying additive that doesn't interfere with the photochemical reaction but significantly improves water repellency, achieving both functional requirements.
2Reliability
If high molecular weight fluorine-containing polymers are used to improve receding contact angle, then water repellency increases, but manufacturing complexity and purification difficulty increase
Solution Approach 1:
The patent specifies an optimal molecular weight range (1,000-100,000) for the fluorine-containing polymer to balance performance and manufacturability. Polymers within this range achieve sufficient receding contact angle (60° or more) while maintaining good solubility and being amenable to standard purification techniques like precipitation and filtration, avoiding the handling difficulties of high molecular weight polymers.
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 fluorine-containing polymer composition achieves improved receding contact angles, minimizing watermarks and component elution, ensuring high-speed scanning exposure without defects and maintaining excellent depth of focus.
Implementation Method 1
a fluorine-containing polymer which leads to a receding contact angle between water and a resist film formed from a radiation-sensitive resin composition containing the fluorine-containing polymer of 60° or more
Data Source
AI summary
An object of the present invention is to provide a novel fluorine-containing polymer, a radiation-sensitive resin composition for liquid immersion lithography which contains the fluorine-containing polymer, which leads to a pattern having an excellent shape and excellent depth of focus, wherein the amount of an eluted component in a liquid for liquid immersion lithography such as water that comes in contact with the resist during exposure in liquid immersion lithography is little, and which provides a larger receding contact angle between the resist film and the liquid for liquid immersion lithography such as water, and a method for purifying the fluorine-containing polymer. The present resin composition comprises a novel fluorine-containing polymer (A) containing repeating units represented by the general formulae (1) and (2) and having Mw of 1,000-50,000, a resin (B) having an acid-unstable group, a radiation-sensitive acid generator (C), a nitrogen-containing compound (D) and a solvent (E).