Positive Resist Composition for EUV and Electron Beam Lithography
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Solution Overview
Problem
Current positive resist compositions for semiconductor device processing face challenges in achieving high sensitivity and exposure latitude while maintaining aging stability and preventing acid diffusion, especially when using electron beam or EUV light, which affects the formation of ultrafine patterns in sub-micron regions.
Innovation Solution
A positive resist composition incorporating an acid-decomposable resin with specific acid-decomposable groups, a high concentration of acid generators, and a basic compound to optimize acid generation efficiency and diffusion, along with a surfactant to enhance pattern formation and stability, is developed. The composition includes a resin with acid-decomposable side chains and a hydroxystyrene repeating unit, an acid generator that generates acids upon irradiation, and a basic compound to control acid diffusivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the concentration of the photoacid generator is raised to elevate acid generation efficiency and sensitivity, then sensitivity is improved, but the photoacid generator aggregates, deteriorates in aging stability or precipitates
Solution Approach 1:
A glass transition type regulator is introduced as an intermediary substance to prevent aggregation of the photoacid generator at high concentrations. This regulator acts as a mediator between the photoacid generator molecules, maintaining their dispersion and stability in the resist composition without reducing acid generation efficiency.
Solution Approach 2:
The glass transition temperature of the resist composition is adjusted to a specific range (50°C to 150°C) by adding the glass transition type regulator. This parameter change in the resist matrix prevents photoacid generator aggregation while maintaining high concentration and aging stability.
2Reliability
If the amount of deprotection per the number of acids generated is increased to achieve high sensitivity, then sensitivity is improved, but acid diffusion occurs and exposure latitude deteriorates
Solution Approach 1:
The acid-decomposable groups are pre-installed on the resin molecules before exposure. Upon acid generation, these groups rapidly decompose and transform the resin from alkali-insoluble to alkali-soluble state, achieving high sensitivity without requiring extensive acid diffusion, thereby preserving exposure latitude.
Solution Approach 2:
The deprotection reaction occurs locally at the sites where acid is generated, creating a localized transformation of resin solubility. This localized quality change ensures high sensitivity while limiting acid diffusion, as the chemical transformation happens precisely where needed rather than requiring broad diffusion.
3Reliability
If acid diffusion is encouraged to cause deprotection reaction for high sensitivity, then sensitivity is improved, but process margin such as exposure latitude deteriorates
Solution Approach 1:
The resin is pre-modified with acid-decomposable groups that can rapidly decompose upon acid generation. This preliminary preparation enables immediate deprotection at the exposure sites, achieving high sensitivity without relying on acid diffusion, thus maintaining broad exposure latitude and process margin.
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 solution provides high sensitivity, improved exposure latitude, and enhanced aging stability, enabling the formation of precise patterns in the sub-micron region with reduced acid diffusion, thus addressing the limitations of existing technologies.
Implementation Method 1
The photoacid generator is decomposed upon exposure to generate an acid
Implementation Method 2
this acid decomposes the acid-decomposable group while diffusing in the resist film
Implementation Method 3
this acid decomposes the acid-decomposable group while diffusing in the resist film, whereby the resin is insolubilized to alkali
Data Source
AI summary
A positive resist composition for use with electron beam, X-ray or EUV and a pattern forming method using the positive resist composition are provided, the positive resist composition including: (A) a resin capable of decomposing under an action of an acid to increase a dissolution rate in an aqueous alkali solution; (B) a compound capable of generating an acid upon irradiation with actinic rays or radiation; (C) a basic compound; and (D) an organic solvent, wherein the entire solid content concentration in the resist composition is from 1.0 to 4.5 mass% and a ratio of (B) the compound capable of generating an acid upon irradiation with actinic rays or radiation is from 10 to 50 mass% based on the entire solid content.