High damage threshold anti-reflectors by physical vapor deposited amorphous fluoropolymer

摘要

High laser-resistant anti-reflective coatings were made from an amorphous fluoropolymer (Teflon AF2400) material by physical vapor deposition. Single layers of Teflon AF2400 were thermally deposited in a vacuum chamber. Refractive index and adhesion of the coatings were determined as a function of deposition rate (2 to 20 (Angstrom)/s), substrate temperature (20 to 200C), and glow-discharge bias potential ((minus)1500 to 1500 V). An anti-reflective coating of an amorphous fluoropolymer (Teflon AF2400) had a laser resistance of > 47 J/cm(sup 2) (1.06 (mu)m, 3-ns pulselength) and is transparent from 200 nm to 1600 nm. The majority of the coatings had a 1.30 refractive index, similar to that of the bulk material. Scanning electron microscopy and preliminary nuclear magnetic resonance observations indicated that morphological changes caused the variations in the refractive index rather than compositional changes. The coatings adhered to fused silica and silicon wafers under normal laboratory handling conditions. Scotch tape with 12.6 gr/mm tension was sufficient to pull off every coating from fused silica substrates.