EUV Resist Laminate With Multilayer Reflector for Sensitivity and LWR
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Solution Overview
Problem
EUV lithography faces challenges in achieving high sensitivity while maintaining line width roughness (LWR) and hole critical dimension uniformity (CDU) due to fluctuations in photon exposure, which are exacerbated by the localization and agglomeration of base polymers and acid generators.
Innovation Solution
A pattern forming method using EUV lithography with a multilayer reflective film layer disposed between the substrate and resist upper layer film, where materials with differing refractive indices are alternately laminated to enhance sensitivity and maintain LWR, comprising high and low refractive index films made of specific materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If EUV exposure is performed with conventional resist, then sensitivity is reduced due to photon fluctuations, but maintaining LWR requires lowering PEB temperature which further reduces sensitivity
Solution Approach 1:
A multilayer reflective film is introduced as an intermediary layer between the substrate and the resist. This film includes a lower reflective film and an upper reflective film with different refractive indices, creating optical interference that enhances EUV light reflection and increases the effective photon dose reaching the resist, thereby improving sensitivity without compromising LWR
Solution Approach 2:
The invention changes the optical parameters of the system by introducing materials with specific refractive index differences (Δn ≥ 0.02) in the reflective film. This parameter change optimizes the reflectivity and light distribution, allowing the resist to receive sufficient photon energy for high sensitivity while maintaining controlled acid diffusion for good LWR
2Manufacturing precision
If the amount of quencher is increased to reduce LWR degradation, then sensitivity is reduced
Solution Approach 1:
The multilayer reflective film acts as an optical intermediary that compensates for the reduced photon efficiency caused by increased quencher content. By enhancing light reflection and distribution, it ensures sufficient energy delivery to the resist even when quencher concentration is elevated for better LWR control
3Manufacturing precision
If multiple exposure processes are used for finer patterns, then manufacturing complexity and cost increase
Solution Approach 1:
The invention changes the optical parameters of the lithography system by introducing the multilayer reflective film with optimized refractive index differences. This enables single-exposure formation of finer patterns by enhancing light-matter interaction, avoiding the need for multiple exposure steps and their associated complexity
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 achieves higher sensitivity and maintains LWR performance by utilizing the multilayer reflective film layer's high reflectivity for EUV light, allowing for precise pattern formation on substrates.
Implementation Method 1
the multilayer reflective film layer has a structure in which two or more materials different in refractive index n at a wavelength of the EUV light are alternately laminated
Implementation Method 2
the multilayer reflective film layer's high reflectivity for EUV light
Implementation Method 3
irradiating the resist upper layer film with EUV light; and developing the resist upper layer film to form a pattern
Data Source
AI summary
The present invention is a pattern forming method using EUV lithography, the pattern forming method including steps of: forming a resist upper layer film on at least one surface side of a substrate; irradiating the resist upper layer film with EUV light; and developing the resist upper layer film to form a pattern, wherein a multilayer reflective film layer is disposed between the substrate and the resist upper layer film, and the multilayer reflective film layer has a structure in which two or more materials different in refractive index n at a wavelength of the EUV light are alternately laminated. The present invention provides: a pattern forming method and a laminate that can contribute to sensitivity enhancement while maintaining LWR of a resist upper layer film are provided.