High-sp3 Carbon Underlayer for Lower-Dose EUV Lithography
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Solution Overview
Problem
EUV lithography faces challenges with low photon absorption and dose requirements due to high energy photons, leading to poor lithography structure quality and increased photon shot noise, especially at small sizes, and existing amorphous carbon layers do not provide dose reduction.
Innovation Solution
A cyclical deposition process, such as plasma-enhanced atomic layer deposition, is used to form an underlayer with a high sp3 carbon content, which includes exposing the substrate to precursors and reactants in alternating pulses, followed by purges, to create a carbon underlayer that enhances photon absorption and reduces the required dose.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high energy EUV photons are used for lithography, then resolution is improved, but photon absorption becomes more difficult and dose requirements increase
Solution Approach 1:
An amorphous carbon underlayer is introduced as an intermediary between the substrate and the photosensitive resist. This underlayer acts as a mediator that absorbs EUV photons and generates secondary electrons, which then initiate the chemical changes in the resist. This intermediary approach solves the problem of direct photon absorption difficulty by using the carbon layer to convert photon energy into a form more effective for resist modification.
Solution Approach 2:
The invention changes the physical and chemical parameters of the underlayer by using amorphous carbon with specific properties (sp3 hybridization, controlled density, specific thickness). By optimizing these parameters, the underlayer achieves maximum photon absorption efficiency and secondary electron generation, directly addressing the photon absorption problem while maintaining resolution.
2Productivity
If continuous carbon deposition is used for high throughput, then productivity is improved, but dose reduction effect is not achieved
Solution Approach 1:
The invention changes the deposition parameters from continuous to cyclical, and controls the carbon microstructure through parameters such as deposition temperature, precursor selection, and cycle timing. These parameter changes enable the formation of amorphous carbon with high sp3 content that provides dose reduction, while maintaining high throughput through optimized cyclical deposition rates.
Solution Approach 2:
The continuous deposition process is replaced with a cyclical deposition process that alternates between carbon deposition phases and controlled interruption phases. This periodic action allows for the formation of amorphous carbon with specific microstructural properties that enable dose reduction, while the overall process maintains high productivity through efficient cycle timing.
3Productivity
If amorphous carbon layers are deposited using high growth rate methods, then productivity is improved, but dose reduction effect is not achieved
Solution Approach 1:
The invention optimizes deposition parameters including temperature, precursor type, and cycle timing to control carbon microstructure. By adjusting these parameters, the process achieves the formation of amorphous carbon with high sp3 hybridization content, which provides the necessary dose reduction effect while maintaining acceptable deposition rates for practical manufacturing.
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 dose reduction and improved lithography structure quality by increasing the sp3 carbon content in the underlayer, offering better etch contrast and lower line roughness while maintaining pattern quality at lower doses.
Implementation Method 1
A cyclical deposition process, such as plasma-enhanced atomic layer deposition, is used to form an underlayer with a high sp3 carbon content, which includes exposing the substrate to precursors and reactants in alternating pulses
Implementation Method 2
ones from the plurality of deposition cycles further comprising a reactant pulse that comprises exposing the substrate to a reactant; wherein the reactant pulse comprises generating a plasma and wherein the reactant comprises one or more plasma-generated species
Data Source
AI summary
Methods, related structures, and related systems for lithography, particularly extreme ultraviolet lithography (EUV). Presently disclosed methods can comprise forming a carbon underlayer having a high sp3 carbon content. Presently disclosed methods can comprise forming a carbon underlayer by means of a cyclical deposition process such as plasma-enhanced atomic layer deposition.