Coatings on reflective mask substrates

In a process for fabricating a mask substrate containing at least a multilayer structure on the front side of a substrate, the improvement comprising:

• forming the substrate of low thermal expansion material,
• forming a layer of material intermediate the substrate and the multilayer structure to enhance defect inspection, improve surface finishing, reduce defect levels, and correct stress imbalance,
• said layer of material being selected from the group consisting of silicon, molybdenum, chromium, chromium oxynitride, TaSi, and Mo/Si multilayers, and
• forming at least one layer of material on the backside of the substrate to facilitate at least one of the group of electrostatic chucking, enhance defect inspection and correct for bowing of the substrate caused by stress imbalance.

A transparent EUVL mask substrate, comprising:

• a substrate composed of low thermal expansion material,
• a first layer of silicon on a frontside of said substrate,
• a multilayer structure on said first layer of silicon,
• a second layer of silicon on a backside of said substrate, and
• a layer of conductive material on said second layer of silicon.