Graphene EUV Pellicle Manufacturing for Transmittance and Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional organic pellicles for EUV lithographic apparatus suffer from low transmittance and mechanical instability, posing challenges for protecting photomasks from airborne contamination and defects in silicon wafers.
Innovation Solution
A manufacturing method involving chemical vapor deposition (CVD) to laminate and transfer graphene films onto a thermal release tape, followed by heat treatment, cutting, and attachment to a pellicle frame, allowing for a graphene membrane with adjustable thickness and high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional organic pellicles are used for EUV lithographic apparatus, then the photomask can be protected from airborne contamination, but the transmittance is low and mechanical stability is poor
Solution Approach 1:
The patent changes the material parameter from conventional organic materials to graphene, which has fundamentally different optical and mechanical properties. Graphene's unique two-dimensional structure provides both high transmittance (92-96% for EUV light) and exceptional mechanical stability, resolving the contradiction between these two requirements.
Solution Approach 2:
The patent creates a composite structure by transferring graphene onto a pellicle frame substrate. This composite approach combines the optical transparency and mechanical strength of graphene with the structural support of the substrate, achieving both high transmittance and mechanical stability required for EUV lithography.
2Strength
If graphene thickness is increased to improve mechanical stability, then mechanical strength improves, but transmittance decreases
Solution Approach 1:
The patent precisely controls the graphene thickness parameter by adjusting the number of stacking layers. By optimizing the stack count, the patent achieves the minimum thickness required to provide mechanical strength while maintaining transmittance above 90%, thus resolving the trade-off between strength and transmittance.
Solution Approach 2:
Instead of using a single thick graphene layer, the patent employs multiple thin layers stacked together. This partial action approach provides sufficient mechanical strength through cumulative effect while each individual layer remains thin enough to maintain high transmittance, achieving both requirements simultaneously.
3Reliability
If multiple graphene layers are stacked to improve mechanical stability, then mechanical strength increases, but manufacturing complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-transferring multiple graphene layers onto a temporary substrate (thermal release tape) before final attachment to the pellicle frame. This preliminary stacking and consolidation simplifies the final assembly process, reducing manufacturing complexity while achieving the required mechanical stability through multi-layer stacking.
Solution Approach 2:
The patent uses a thermal release tape as an intermediary substrate during the manufacturing process. This mediator allows for easy stacking, handling, and alignment of multiple graphene layers before final transfer to the pellicle frame, significantly simplifying the manufacturing process of multi-layer graphene structures.
4Illumination intensity
If pellicle thickness is reduced to 60 nm or less to achieve high transmittance, then transmittance improves, but mechanical stability deteriorates
Solution Approach 1:
The patent changes the material composition parameter from conventional thick organic materials to ultra-thin graphene stacks. Graphene's exceptional strength-to-thickness ratio enables the pellicle to maintain mechanical stability at thicknesses of 60 nm or less while achieving the required >90% transmittance for EUV lithography.
Solution Approach 2:
The patent employs graphene as a flexible thin film material that provides mechanical support despite its ultra-thin profile. The two-dimensional honeycomb structure of graphene gives it exceptional mechanical strength, allowing the pellicle to be extremely thin (60 nm or less) while maintaining the mechanical stability needed to protect the photomask.
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 graphene membrane pellicle achieves high transmittance (92-96%) and mechanical stability, reducing defects and costs by enabling thinner graphene stacks and minimizing product defects.
Implementation Method 1
graphene is deposited on a catalytic metal foil
Implementation Method 2
the thermal release tape of the graphene stacking film is attached to a substrate film and the thermal release tape is thermally separated, thereby transferring the stacked graphene onto the substrate film
Implementation Method 3
A stacked graphene heat treatment step in which a certain amount of heat is applied to the graphene transfer film to enhance the stacked graphene
Data Source
Figure 1
Figure 2~4(b)
Figure 5~6b(b)
AI summary
The present invention pertains to a manufacturing method of a graphene membrane pellicle for an extreme ultra violet (EUV) lithographic apparatus. The present invention provides a manufacturing method of a graphene membrane pellicle for an EUV lithographic apparatus, whereby a pellicle for protecting photomasks in an EUV lithographic apparatus using a graphene-deposited catalytic metal film can be produced. A graphene membrane pellicle produced by this graphene membrane pellicle manufacturing method uses layered graphene and thus has the advantage of being adjustable in thickness.