Positive Resist Composition for High-Resolution Lithography
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Solution Overview
Problem
Current positive resist compositions face challenges in achieving high resolution, minimal edge roughness, and improved etching resistance, especially as feature sizes reduce, leading to issues with acid diffusion and sensitivity in electron beam and extreme ultraviolet lithography.
Innovation Solution
A chemically amplified positive resist composition is developed using a polymer with recurring units of 2-indane or 2-tetrahydronaphthalene-substituted tertiary carboxyl groups, which suppresses acid diffusion and enhances dissolution contrast and etching resistance, forming a resist film with high resolution and minimal edge roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the accelerating voltage of the electron gun is increased to enable further size reduction, then the resolution and dimensional control are improved, but the sensitivity of the resist film is reduced
Solution Approach 1:
The patent changes the chemical composition parameters of the resist film by incorporating specific polymers with acid-labile groups and carboxyl groups in controlled amounts. This chemical parameter modification enables the resist to maintain high sensitivity even when exposed to high-energy electrons (50-100 keV), resolving the contradiction between resolution improvement and sensitivity loss
Solution Approach 2:
The patent creates a composite resist system combining multiple functional components: polymers with acid-labile groups (for sensitivity), polymers with carboxyl groups (for etching resistance), and optional basic compounds (for neutralization). This composite approach allows simultaneous optimization of sensitivity, resolution, and etching resistance that single-material solutions cannot achieve
2Measurement precision
If the resist film thickness is reduced to facilitate pattern feature reduction and prevent collapse, then the resolution is improved, but the etching resistance is reduced
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating polymers with carboxyl groups (0.1-10 mmol/g) that provide enhanced etching resistance. This compositional parameter change allows thin resist films (50-200 nm) to maintain sufficient etching resistance despite reduced thickness, enabling both high resolution and adequate pattern strength
Solution Approach 2:
The patent creates local quality differentiation within the resist film structure by using polymers with specific functional groups at different locations. The acid-labile groups provide sensitivity in the exposure zone, while carboxyl groups distributed throughout the film provide etching resistance, allowing the film to have different functional properties in different aspects
3Strength
If the polymerization conversion is increased to improve the properties of the resist film, then the etching resistance is improved, but the solubility in organic solvents is reduced
Solution Approach 1:
The patent optimizes the polymerization conversion parameter to a specific range (5-50%) rather than maximizing it. At this controlled conversion level, the resist film achieves sufficient etching resistance while maintaining adequate solubility in organic solvents for proper coating and processing. This parameter optimization resolves the contradiction between excessive crosslinking and processability
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 resist composition exhibits high contrast, resolution, and etching resistance, making it suitable for fabricating VLSIs and photomasks with improved pattern profiles and process adaptability.
Implementation Method 1
chemically amplified positive resist composition
Implementation Method 2
a polymer having carboxyl groups whose hydrogen is substituted by an acid labile group
Implementation Method 3
chemically amplified positive resist composition
Data Source
AI summary
A positive resist composition comprising a polymer having carboxyl groups substituted with an acid labile group having formula (1) exhibits a high contrast of alkaline dissolution rate before and after exposure, a high resolution, a good pattern profile and minimal edge roughness. In formula (1), A is —(CR22)m—, B is —(CR52)n—, R2 and R5 are hydrogen or alkyl, m and n are 1 or 2, R3 is alkyl, alkenyl, alkynyl or aryl, R6 is alkyl, alkoxy, alkanoyl, alkoxycarbonyl, hydroxyl, nitro, aryl, halogen, or cyano, and p is 0 to 4.