Patent ID: 9726972
Date: 2017-08-08
CPC Classifications: C23F,G03F,H01L

Claim:
1. A mask blank having a structure in which a light semitransmissive film and a light shielding film are laminated on a main surface of a transparent substrate, wherein the light semitransmissive film is formed from a material which can be dry etched with an etching gas containing a fluorine-based gas, wherein the light shielding film at least includes a laminated structure of a lower layer and an upper layer, wherein the lower layer is formed from a material containing tantalum and substantially free from hafnium, zirconium, and oxygen, wherein the upper layer is formed from a material containing tantalum and one or more elements selected from hafnium and zirconium, and free from oxygen excluding a surface layer thereof, and wherein an etching stopper film provided between the light semitransmissive film and the lower layer is made of a material having etch selectivity with respect to the lower layer in dry etching with an etching gas containing a chlorine-based gas and no oxygen gas.