Photoresist Underlayer Composition for EUV Absorption and Pattern Stability
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Solution Overview
Problem
EUV lithography faces challenges in resist sensitivity and pattern resolution due to low photon density and spatial uniformity, leading to slow photo-speeds and potential pattern collapse.
Innovation Solution
A polymeric photoresist underlayer composition comprising specific repeating units to enhance EUV photon absorption cross-section and improve adhesion, featuring a polymer with three or more different repeating units, a crosslinker, and a solvent, applied to form a film layer over a substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional photoresist materials are used in EUV lithography, then the absorption cross-section at 13.5 nm is limited by the atomic properties of typical atoms (carbon, oxygen, hydrogen, nitrogen), but this results in low photon density and slow photo-speeds
Solution Approach 1:
The patent changes the chemical composition parameters of the photoresist by incorporating iodine-containing monomers and polymers, which have remarkably high EUV light absorption cross-section. This parameter change in material composition directly addresses the low absorption cross-section issue while improving photo-speed
Solution Approach 2:
The patent creates a composite photoresist material system combining iodine-containing polymers with other resist components. This composite approach leverages the high absorption cross-section of iodine while maintaining the functional properties needed for lithography, resolving the contradiction between absorption efficiency and photo-speed
2Use of energy by moving object
If low photon density is used in EUV imaging, then the absorption cross-section can be increased, but this leads to decreased spatial photon uniformity and poor pattern resolution
Solution Approach 1:
The patent optimizes the concentration and distribution parameters of iodine-containing compounds in the photoresist composition. By carefully controlling these parameters, the patent achieves high absorption cross-section while maintaining spatial photon uniformity and pattern resolution
3Use of energy by moving object
If higher EUV source power or longer exposure time is used to compensate for low sensitivity, then absorption can be improved, but this increases processing time and reduces throughput
Solution Approach 1:
The patent changes the material parameters of the photoresist to have inherently higher absorption cross-section through iodine incorporation. This allows achieving sufficient exposure at lower source power and shorter exposure times, directly reducing the time loss in the lithography process
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
Enhances EUV photon absorption, improves photo-speed, and reduces pattern collapse, resulting in higher resolution and better pattern transfer.
Implementation Method 1
Iodine has remarkably high EUV light absorption cross-section... increase the absorption cross-section at 13.5 nm
Implementation Method 2
EUV light absorption cross-section and secondary electron generation yield are important factors for EUV sensitivity
Data Source
AI summary
A composition comprising a polymer, the polymer comprising: repeating units derived from a monomer of Formula A1, Formula A2, or Formula A3, repeating units derived from a monomer of Formula B1, Formula B2, Formula B3, or Formula B4, and repeating units derived from a monomer of Formula C1 or Formula C2, the structures of each as described herein. A coated substrate including a substrate, a photoresist underlayer formed from composition above, and a photoresist layer on the photoresist underlayer.