ASML and the University of Twente have posted a preprint showing significant increase in the IR emissivity of SiN membranes by addition of a 2-4 nm ruthenium film. The improved emissivity is enough to lower the temperature of EUV-exposed membranes from >1500K to ~500K in 10-4 mbar helium. Thus, uncoated membranes glow white hot and collapse, while coated membranes emit no visible radiation and survive quite well.
Reference: P J van Zwol, et al., “Emissivity of freestanding membranes with thin metal coatings”, arXiv:1511.06111.