Pattern Formation Method Using Low-Concentration TMAH Developer
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Solution Overview
Problem
Current pattern formation methods in ultramicrolithography and photofabrication processes, especially using liquid-immersion projection exposure with far-ultraviolet light, suffer from scum and watermark defects due to the limitations of traditional chemical amplification techniques and alkali developer concentrations.
Innovation Solution
A method involving a resin composition that includes an acid-decomposable resin, an acid generator, and a hydrophobic resin with fluorine and silicon atoms, exposed to light and developed using a tetramethylammonium hydroxide solution at concentrations less than 2.38 mass %, to reduce scum and watermark defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional chemical amplification technique with standard alkali developer concentration (2.38 mass % TMAH) is used, then dissolution velocity and development efficiency are improved, but scum and watermark defects increase
Solution Approach 1:
The patent changes the concentration parameter of the alkali developer from the standard 2.38 mass % TMAH to a reduced concentration range (0.5-2.0 mass % TMAH). This parameter modification resolves the contradiction by achieving adequate dissolution velocity at lower concentrations while preventing scum and watermark defects that occur at standard concentrations, thus improving both productivity and manufacturing precision simultaneously
2Manufacturing precision
If liquid-immersion projection exposure with far-ultraviolet light is used, then resolution and patterning precision are improved, but scum and watermark defects are generated
Solution Approach 1:
The patent converts the harmful effect of far-ultraviolet light exposure into a beneficial process by using the generated photoacid to catalyze the decomposition of the acid-decomposable resin. This transformation turns the potentially harmful high-energy UV exposure into a controlled chemical reaction that forms the desired pattern while avoiding scum and watermark defects through the specific resin composition and development conditions
3Manufacturing precision
If acid-decomposable resin and hydrophobic resin are used in the photosensitive composition, then pattern quality and defect reduction are improved, but resin composition complexity increases
Solution Approach 1:
The patent employs a composite resin system consisting of multiple components: acid-decomposable resin, hydrophobic resin containing fluorine or silicon atoms, and other necessary photosensitive components. This composite material approach resolves the contradiction by combining the advantages of each resin type to achieve superior pattern quality and defect reduction, while the synergistic effects of the composite system manage the overall complexity through functional integration
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 method effectively forms patterns with reduced scum and watermark defects, enhancing the precision and quality of microchip and high-density information recording medium production.
Implementation Method 1
a compound (B) that generates an acid when exposed to actinic rays or radiation
Implementation Method 2
a resin (A) that exhibits an increased solubility in an alkali developer when acted on by an acid
Implementation Method 3
a resin (C) containing at least one of a fluorine atom and a silicon atom
Data Source
AI summary
Provided is a pattern forming method making it possible to obtain a pattern with less scums and watermark defects. The pattern forming method includes the steps of forming a film from an actinic-ray- or radiation-sensitive resin composition includes a resin (A) that exhibits an increased solubility in an alkali developer when acted on by an acid, a compound (B) that generates an acid when exposed to actinic rays or radiation, and a resin (C) containing at least one of a fluorine atom and a silicon atom, exposing the film to light, and developing the exposed film using a tetramethylammonium hydroxide solution whose concentration is less than 2.38 mass %.