VUV Mask Haze Acceleration Testing
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Solution Overview
Problem
Current mask defect detection methods using ArF excimer lasers are complex, expensive, and time-consuming, providing limited information on haze formation across the entire mask assembly due to localized illumination, which hampers the prediction of mask performance and manufacturing efficiency.
Innovation Solution
Employing a vacuum ultraviolet (VUV) radiation source to illuminate a broader area of the mask assembly, accelerating haze formation and enabling more comprehensive information on haze distribution, thus reducing testing duration and improving prediction accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ArF excimer laser is used for haze detection, then measurement precision is improved, but device complexity increases and productivity decreases
Solution Approach 1:
The patent extracts the essential function of haze detection from the complex ArF excimer laser system and implements it using a simplified LED-based illumination system combined with a spectrometer, eliminating the need for complex optical components while maintaining detection capability
Solution Approach 2:
The patent creates a functional copy of the laser illumination approach using LED light sources that can provide similar broad-spectrum UV illumination for haze detection, thereby achieving the same measurement objective with simpler, more cost-effective components
2Measurement precision
If ArF excimer laser with localized illumination is used, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent segments the mask assembly into multiple regions of interest and systematically illuminates each region using the LED array, enabling comprehensive coverage of the entire mask surface while maintaining detection precision through structured scanning of discrete areas
Solution Approach 2:
The patent implements continuous scanning illumination across the mask assembly using the LED array, eliminating idle time between measurements by continuously moving the illumination and detection across different regions, thereby reducing total testing duration while maintaining measurement quality
3Measurement precision
If ArF excimer laser is used for haze detection, then measurement precision is improved, but loss of time increases
Solution Approach 1:
The patent changes the illumination parameters by using LED light sources with appropriate spectral characteristics and adjusting illumination intensity and scanning speed to optimize the balance between measurement precision and testing duration, achieving rapid yet accurate haze detection
4Productivity
If VUV radiation source is used to illuminate broader area, then productivity is improved, but illumination intensity decreases
Solution Approach 1:
The patent merges multiple LED light sources into an array configuration, combining their individual illumination outputs to achieve both broad area coverage and sufficient illumination intensity simultaneously, thereby resolving the trade-off between coverage area and intensity
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 VUV radiation source significantly reduces haze generation time, providing more accurate and efficient mask performance prediction, enhancing manufacturing efficiency by illuminating a larger area and eliminating the need for complex optical systems.
Implementation Method 1
The high energy photons from the ArF excimer laser trigger photochemical reactions, accelerating haze formation on the mask
Implementation Method 2
a radiation source having a wavelength ranging from about 160 nm to 180 nm is used to illuminate the mask assembly in order to accelerate the haze formation
Data Source
AI summary
A method of testing a photomask assembly includes placing the photomask assembly into a chamber, wherein the photomask assembly includes a pellicle attached to a first side of a photomask. The method further includes exposing the photomask assembly to a radiation source having a wavelength ranging from about 160 nm to 180 nm in the chamber to accelerate haze development, wherein the exposing of the photomask assembly includes illuminating an entirety of an area of the photomask covered by the pellicle throughout an entire illumination time and illuminating a frame adhesive attaching the pellicle to the photomask. The method further includes detecting haze of the photomask following exposing the photomask assembly to the radiation source. The method further includes predicting performance of the photomask assembly during a manufacturing process based on the detected haze of the photomask following exposing the photomask assembly to the radiation source.