Pellicle Frame Reflectance Tuning for Accurate Contaminant Inspection
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Solution Overview
Problem
Existing pellicle frames in lithography systems face challenges in accurately distinguishing scattering light from contaminants due to high reflectance, limiting effective contaminant inspection, especially in EUV lithography where specific wavelength ranges are not adequately addressed.
Innovation Solution
The pellicle frame is designed with a minimum reflectance of up to 20% at wavelengths between 500 to 1,000 nm, allowing for targeted inspection light wavelength selection to minimize scattering and enhance contaminant detection, while enabling various surface treatments without color restrictions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pellicle frame inside surface has high reflectance, then the frame material and coloring methods are flexible, but the scattering light from the frame interferes with contaminant detection
Solution Approach 1:
The pellicle frame inside surface is designed with specific optical properties to minimize reflectance of inspection light (He-Ne laser at 632.8 nm or semiconductor laser at 532 nm). This is achieved by selecting frame materials and applying coloring treatments that absorb inspection light wavelengths, thereby reducing scattering light that would interfere with contaminant detection while maintaining structural integrity
Solution Approach 2:
The reflectance parameter of the pellicle frame inside surface is optimized to be minimal at specific inspection light wavelengths. By controlling the optical parameters (reflectance, absorption) of the frame material and surface treatment, the system achieves high contrast between frame scattering and contaminant scattering, enabling accurate contaminant detection
2Measurement precision
If the reflectance of pellicle frame is reduced to improve inspection accuracy, then contaminant detection is enhanced, but the frame material and coloring options are restricted
Solution Approach 1:
The optical treatment is applied specifically to the inside surface of the pellicle frame where inspection light interacts with contaminants. This localized approach ensures minimal reflectance at the inspection surface while allowing flexibility in frame material selection and overall frame design, as the optical property requirement is confined to a specific location and function
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 design improves contaminant inspection accuracy by reducing frame scattering, allowing effective detection of contaminants and increasing the freedom of surface treatments, particularly suitable for EUV lithography.
Implementation Method 1
the pellicle frame is designed with a minimum reflectance of up to 20% at wavelengths between 500 to 1,000 nm, allowing for targeted inspection light wavelength selection to minimize scattering
Implementation Method 2
The contaminant inspector is generally designed to irradiate laser light of He—Ne laser or semiconductor laser to the pellicle frame and detect light scattering from contaminants by a semiconductor detector (CCD)
Data Source
AI summary
Provided are a pellicle frame, a pellicle, a method for inspecting a pellicle, a pellicle-attached exposure original plate and exposure method, and a method for manufacturing a semiconductor or a liquid crystal display board.