Chemically Amplified Resist Composition for VLSI Patterning
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Solution Overview
Problem
Current chemically amplified positive resist compositions face challenges in achieving high resolution, maintaining a satisfactory pattern profile after development, and ensuring high etching resistance, particularly for microfabrication applications like VLSI manufacturing, due to issues with pattern thinning and heat resistance.
Innovation Solution
A chemically amplified positive resist composition is developed using a polymer with alkoxyisobutoxystyrene-type reactive groups and indene units, combined with a photoacid generator and organic solvent, which forms a resist film with increased dissolution contrast, high resolution, and improved etch resistance, suitable for precise microfabrication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional acid labile groups (tert-butyl, tert-butoxycarbonyl) are used in base resins, then high sensitivity and good dry etching resistance are achieved, but the resist pattern takes on a T-top profile and has poor heat resistance
Solution Approach 1:
The patent changes the chemical structure of the acid labile group from conventional tert-butyl or tert-butoxycarbonyl to alkoxyisobutoxystyrene with specific parameters (R1-R6 groups as defined in formulae 1-5). This parameter change in the molecular structure enables the resin to maintain etching resistance while achieving a satisfactory pattern profile without T-top formation.
Solution Approach 2:
The patent uses a copolymer composite material comprising multiple functional units: alkoxyisobutoxystyrene units (providing acid labile groups), indene units (improving etching resistance), and optionally other styrene derivatives. This composite structure combines the benefits of different functional groups to simultaneously achieve good pattern profile and high etching resistance.
2Shape
If weak acid-cleavable groups (ethoxyethyl, 2-tetrahydropyranyl) are used, then pattern configuration is maintained initially, but the pattern configuration is considerably narrowed with the passage of time between exposure and heat treatment
Solution Approach 1:
The patent changes the acid labile group from weak acid-cleavable ethoxyethyl or 2-tetrahydropyranyl groups to alkoxyisobutoxystyrene groups with specific structural parameters. This parameter change increases the stability of the pattern configuration over time while maintaining the ability to be cleaved by acid during development, preventing pattern narrowing during the storage period.
3Productivity
If some conventional resins are used, then sensitivity is improved, but heat resistance is poor causing lens contamination by outgassing during development
Solution Approach 1:
The patent employs a composite polymer material combining alkoxyisobutoxystyrene units (for acid lability and sensitivity) with indene units (for heat resistance and etching resistance). This composite structure suppresses outgassing during development while maintaining high sensitivity, preventing lens contamination in stepper equipment.
Solution Approach 2:
The patent modifies the thermal stability parameters of the resin by incorporating indene units and specific alkoxyisobutoxystyrene structures, raising the temperature at which outgassing occurs. This parameter change ensures the resin remains stable during development heating while maintaining its chemical amplification sensitivity.
4Manufacturing precision
If pattern film is thinned for reduced feature size, then resolution is improved, but pattern profile degrades due to pattern film becoming thinner
Solution Approach 1:
The patent uses a composite copolymer material where indene units provide enhanced etching resistance and structural integrity to thin pattern films, while alkoxyisobutoxystyrene units provide the necessary acid lability for development. This composite structure maintains a well-defined pattern profile even when the film is thinned to achieve reduced feature sizes of 0.5 μm or less.
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 composition achieves high resolution, a satisfactory resist pattern profile, and enhanced etch resistance, making it suitable for the fabrication of VLSI and other micro-patterning applications.
Implementation Method 1
chemically amplified positive resist composition, comprising as the base resin a polymer containing alkoxyisobutoxystyrene as reactive groups which are decomposable under the action of an acid to increase solubility in alkali
Implementation Method 2
acid-catalyzed chemical amplification positive resists utilize a high-intensity KrF excimer laser as the deep-UV light source
Data Source
AI summary
A hydroxystyrene/indene/alkoxyisobutoxystyrene copolymer having Mw of 1,000-500,000 is formulated as a base resin to give a resist composition, typically chemically amplified positive resist composition. The composition exhibits a high resolution, a satisfactory resist pattern profile after development, and improved etch resistance and is thus suitable as a micropatterning material for the fabrication of VLSI.