Silicon Single Crystal Pellicle for EUV Lithography
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current pellicle films for extreme ultra violet (EUV) lithography face challenges in achieving high transmission, chemical stability, and mechanical durability, with issues such as high absorption coefficients, stress-induced optical property deterioration, and fabrication yield limitations, particularly during handling and exposure processes.
Innovation Solution
A pellicle comprising a silicon single crystal film with a crystal plane inclined 3 to 5° from {100} or {111} planes, supported by a base substrate with a high open area ratio and reinforced with a protection film of materials like SiC, SiO2, or Ru, and a reinforcing frame, enhancing mechanical and chemical stability while maintaining high EUV transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a silicon film is deposited by sputtering or CVD method, then the pellicle film can be formed, but the absorption coefficient in the EUV region becomes high and transmittance becomes low
Solution Approach 1:
The patent changes the crystal structure parameter of silicon from amorphous or polycrystalline to single crystal, which fundamentally alters the absorption coefficient and transmittance characteristics in the EUV region while maintaining the ability to form a pellicle film
Solution Approach 2:
The patent uses a composite structure combining single crystal silicon film with a substrate, where the single crystal silicon provides high EUV transmittance while the substrate provides mechanical support, achieving both ease of manufacture and high reliability
2Ease of manufacture
If a silicon crystal is made into a thin film in pellicle production process, then the pellicle can be formed, but cracks or defects occur during stripping, etching, and handling
Solution Approach 1:
The patent employs a thin single crystal silicon film structure that maintains flexibility and resistance to cracking during handling and processing, while still providing the required dust-proof function for the photomask
Solution Approach 2:
The patent performs preliminary strengthening treatment on the single crystal silicon film before it undergoes stripping, etching, and handling processes, preventing cracks and defects from occurring during these subsequent operations
3Ease of manufacture
If a strong stress is introduced into a silicon crystal by sputtering or CVD methods, then the pellicle film can be formed, but optical film properties deteriorate and become uneven
Solution Approach 1:
The patent changes the deposition method from sputtering or CVD to a method that grows single crystal silicon, which eliminates the introduction of strong stress and maintains uniform optical film properties throughout the pellicle structure
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 solution provides a pellicle with improved mechanical and chemical stability, reduced warpage and distortion, and increased fabrication yield, while ensuring high transmission and cost-effectiveness for EUV lithography applications.
Implementation Method 1
a protection film on at least one surface of the silicon single crystal film... the protection film consists of at least one material of SiC, SiO2, Si3N4, SiON, Y2O3, YN, Mo, Ru and Rh
Implementation Method 2
silicon has relative high transmittance for the light having such a wavelength... the principal plane of the silicon single crystal film is a crystal plane inclined at 3 to 5° from any lattice plane belonging to {100} planes or {111} planes
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3D
AI summary
A pellicle film (11) of a silicon single crystal film and a base substrate (12) supporting the pellicle film are formed of a single substrate using an SOI substrate. The base substrate (12) is provided with an opening whose ratio in area to an exposure region when a pellicle is used on a photomask (an open area ratio) is 60% or more, and provided with a reinforcing frame (12a) in a non-exposure region of the base substrate. Since the pellicle film (11) and the base substrate (12) supporting the pellicle film are formed of the single substrate (an integrated structure), and the base substrate is provided with the reinforcing frame, the effect of increased strength is obtained. Moreover, a principal plane of a silicon single crystal film (11) is a crystal plane inclined at 3 to 5° from any lattice plane belonging to {1100} planes or {111} planes.