Acid-Generating SOC Layer for Low-Dose EUV Lithography
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Solution Overview
Problem
Conventional methods for reducing doses in extreme ultraviolet (EUV) lithography to increase throughput often compromise critical dimension (CD) uniformity, roughness, or lead to defects such as nanobridges and collapses, particularly at the bottom of the photoresist in line/space and contact hole applications.
Innovation Solution
The use of an acid-generating spin-on carbon (SOC) layer comprising a carbon-rich polymer and an acid generator, which generates acid upon exposure to EUV radiation, allowing the acid to diffuse through a hardmask layer and compensate for insufficient acid at the bottom of the photoresist, thereby reducing the required EUV dose without sacrificing device quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to reduce EUV dose to increase throughput, then productivity is improved, but manufacturing precision deteriorates due to compromised CD uniformity and increased roughness
Solution Approach 1:
An acid-generating spin-on carbon (SOC) layer is introduced as an intermediary between the substrate and the photoresist. This SOC layer contains acid generators that, when exposed to EUV radiation, produce acid to diffuse into the photoresist and enhance the chemical amplification effect. This mediator enables dose reduction while maintaining or improving CD uniformity and reducing line width roughness, thereby resolving the contradiction between throughput and manufacturing precision
2Productivity
If conventional methods are used to reduce EUV dose, then productivity is improved, but reliability deteriorates due to increased defects such as nanobridges and collapses
Solution Approach 1:
The acid-generating SOC layer acts as a mediator that provides additional acid to the photoresist during EUV exposure. This enhanced acid generation improves the development contrast and reduces the formation of defects such as nanobridges and collapses, thereby maintaining high reliability even at reduced doses that increase throughput
3Productivity
If conventional methods are used to reduce EUV dose, then productivity is improved, but manufacturing precision deteriorates due to increased line width roughness
Solution Approach 1:
The acid-generating SOC layer serves as an intermediary that enhances acid generation in the photoresist, leading to more uniform polymerization and reduced line width roughness. This allows for dose reduction and increased throughput while maintaining or improving the quality of the fabricated features
4Productivity
If conventional methods are used to reduce EUV dose, then productivity is improved, but manufacturing precision deteriorates due to scum and top loss
Solution Approach 1:
The acid-generating SOC layer acts as a mediator that provides enhanced acid generation throughout the photoresist thickness, improving the uniformity of the development process. This reduces scum formation at the bottom and top loss at the surface, thereby maintaining profile quality while enabling dose reduction for increased throughput
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 a lower EUV dose requirement, improving CD uniformity and reducing defects, maintaining or enhancing the quality of microelectronic structures without disrupting the process window.
Implementation Method 1
an acid generator, which generates acid upon exposure to EUV radiation
Implementation Method 2
allowing the acid to diffuse through a hardmask layer
Data Source
AI summary
Methods of using an acid-generating, spin-on carbon (SOC) layer for EUV lithography are disclosed. The methods can be used to reduce the dose, scumming, and/or nanobridges induced by insufficient acid at the bottom of a photoresist for both line/space (LS) and contact hole (CH) applications. The methods may improve uniformity in acid compensation at the bottom of the photoresist via bottom-up diffusion of an acid from the acid-generating layer. By utilizing the acid-generating SOC layer under a spin-on silicon hardmask or spin-on glass (SOG), dose reduction has been realized.