Patterned Carbon Layer Formation Using EUV Without Resist
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Solution Overview
Problem
Current methods for forming patterned graphene layers in semiconductor devices face challenges in achieving high accuracy, speed, and cost-effectiveness, particularly due to the need for high temperatures and the use of resist overlayers, which can lead to defects and roughness in extreme ultraviolet (EUV) lithography.
Innovation Solution
A method involving the irradiation of a solid structure with extreme ultraviolet radiation in the presence of a carbon-containing precursor to form a patterned carbon layer without the need for high temperatures or resist overlayers, utilizing photo-electrons to catalyze the formation of carbon, allowing for high spatial resolution and efficient deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If chemical vapor deposition (CVD) or silicon sublimation from SiC is used to produce graphene, then graphene can be formed on metal surfaces or substrates, but high temperatures are required which increases processing complexity and cost
Solution Approach 1:
The patent replaces thermal energy input with electromagnetic radiation (EUV photons) to drive the chemical reactions. Instead of heating the substrate to high temperatures for CVD or sublimation, EUV radiation directly induces photoelectric effects and chemical reactions in the carbon-containing precursor, forming graphene at lower temperatures. This substitution of thermal processing with photonic processing resolves the contradiction between achieving reliable graphene formation and avoiding high temperature processing.
2Manufacturing precision
If traditional lithography with resist overlayers is used to form patterns, then patterns can be transferred to the substrate, but the resist must be peeled away which adds processing steps and can cause defects
Solution Approach 1:
The patent extracts and eliminates the resist overlayer from the patterning process. Instead of using a separate resist material that needs to be deposited, patterned, and then removed, the invention directly forms the patterned carbon layer through EUV-induced decomposition of a carbon-containing precursor. The carbon layer itself serves as both the pattern definition and the final product, removing the need for resist deposition and peel-away steps, thus reducing device complexity while maintaining manufacturing precision.
Solution Approach 2:
The patent merges the patterning function and the graphene formation function into a single step. In traditional approaches, patterning (via resist) and graphene formation (via CVD) are separate processes. Here, the EUV radiation simultaneously patterns the substrate and forms the carbon layer in the exposed regions, combining what were previously distinct processing steps into one integrated operation, thereby reducing the number of processing steps and potential defects.
3Manufacturing precision
If EUV lithography is used to form smaller features, then higher spatial resolution is achieved, but the resist thickness must be reduced to avoid high aspect ratio features which are prone to collapse
Solution Approach 1:
The patent uses a gaseous carbon-containing precursor that is present only during the EUV irradiation process and then decomposes to form the carbon layer. This precursor does not require forming a stable, thick resist structure like traditional EUV resists, because it is consumed during the reaction to form the desired patterned carbon layer. The precursor molecules are transient and convert directly to the final product, avoiding the need for thick, structurally vulnerable resist layers while maintaining high spatial resolution.
4Manufacturing precision
If the photoresist layer thickness is decreased to achieve smaller critical dimensions, then higher numerical aperture can be used, but photon absorption decreases leading to higher shot noise and defects
Solution Approach 1:
The patent changes the fundamental parameter of how carbon is delivered to the substrate. Instead of relying on photon absorption through a thin resist layer to trigger chemical changes throughout the resist thickness, the invention uses EUV radiation to directly decompose carbon-containing precursor molecules in the gas phase or on the surface. This approach does not depend on the same photon absorption physics that limit thin resist performance, allowing high numerical aperture and small critical dimensions without the shot noise and absorption efficiency problems that plague traditional EUV resist systems.
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
This approach enables the formation of patterned carbon layers with high precision and speed, reducing defects and processing steps, while maintaining the flexibility to use either gaseous or solid-state precursors, thus addressing the limitations of existing techniques in EUV lithography.
Implementation Method 1
the irradiation generates photo-electrons from the solid structure; the photo-electrons catalyse a reaction involving the carbon-containing precursor
Implementation Method 2
the radiation interacts with the solid structure in the selected portion to cause formation of a layer of carbon
Data Source
AI summary
Methods and apparatus for forming a patterned layer of carbon are disclosed. In one arrangement, a selected portion of a surface of a solid structure is irradiated with extreme ultraviolet radiation in the presence of a carbon-containing precursor. The radiation interacts with the solid structure in the selected portion to cause formation of a layer of carbon in the selected portion from the carbon-containing precursor. The layer of carbon is formed in a pattern defined by the selected portion.