- Purity: high purity completely eliminates contamination.
- Chemical resistance: high stability against a variety of solvents.
- Heat resistance: high dimensional stability over a wide temperature range.
- Transparency: high transmissivity over a wide range of wavelengths from UV to IR.
- Fluorescence: no fluorescence over a wide range of wavelengths from UV to IR.
- Dielectric properties: low dielectric loss even at GHz frequencies.
- Surface: high flatness, high uniformity of thickness and smooth surface, thanks to techniques developed for photomask substrates used in LSI manufacturing.