Synthetic Quartz Glass Birefringence Sorting via Liquid Coating
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Solution Overview
Problem
Current methods for producing synthetic quartz glass substrates are inefficient in achieving low birefringence, high flatness, and flawlessness, leading to low productivity and high costs, especially for use in excimer laser lithography and nanoimprint lithography, where birefringence issues affect exposure performance and pattern accuracy.
Innovation Solution
A method involving coating specific liquids on synthetic quartz glass blocks or plates to measure and sort birefringence distribution, allowing for early identification and sorting of acceptable substrates, thereby reducing unnecessary machining steps and increasing productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If birefringence measurement is performed only after polishing to mirror-like surface, then measurement accuracy is improved, but productivity deteriorates due to unnecessary machining of high-birefringence blocks
Solution Approach 1:
The patent applies preliminary action by coating the synthetic quartz glass block with a liquid having high transmittance at the measurement wavelength before polishing. This allows birefringence measurement to be performed on the rough-surfaced block, enabling early identification and rejection of high-birefringence blocks before time-consuming polishing operations are performed, thus resolving the contradiction between measurement accuracy and productivity
Solution Approach 2:
The patent introduces a liquid coating as an intermediary substance that bridges the gap between the rough glass surface and the light used for birefringence measurement. The liquid fills surface irregularities and provides optical transparency, enabling accurate measurement without requiring the surface to be polished to a mirror finish, thereby maintaining measurement precision while improving productivity
2Manufacturing precision
If all synthetic quartz glass blocks undergo complete machining process, then substrate quality is ensured, but costs increase due to processing of unsuitable blocks
Solution Approach 1:
The patent performs preliminary birefringence measurement on rough-surfaced blocks using liquid coating, enabling early sorting of suitable and unsuitable blocks. This preliminary action prevents unnecessary machining of high-birefringence blocks, reducing production costs while maintaining quality consistency by ensuring only suitable blocks undergo the complete manufacturing process
Solution Approach 2:
The patent extracts or removes unsuitable high-birefringence blocks from the production flow at an early stage through preliminary measurement and sorting. This prevents these blocks from consuming additional machining resources and ensures that only suitable blocks proceed through the complete manufacturing process, thereby reducing costs while maintaining quality standards
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 production of synthetic quartz glass substrates with desired birefringence values, improving productivity and reducing costs by sorting out suitable substrates at an early stage, ensuring high-quality substrates for advanced lithography applications.
Implementation Method 1
the liquid having a transmittance of at least 99.0%/mm at the wavelength of birefringence measurement
Implementation Method 2
measuring a birefringence distribution on the block by letting light enter one coated surface and exit the other coated surface
Data Source
AI summary
A synthetic quartz glass substrate is prepared by furnishing a synthetic quartz glass block, coating two opposite surfaces of the block with a liquid having a transmittance of at least 99.0%/mm at the wavelength of birefringence measurement, measuring a birefringence distribution on the block by letting light enter one coated surface and exit the other coated surface, and sorting the block to an acceptable group or unacceptable group, based on the measured birefringence distribution.