Photomask blank
View Patent ↗A photomask blank has a light-shielding film composed of a single layer of a material containing a transition metal, silicon and nitrogen or a plurality of layers that include at least one layer made of a material containing a transition metal, silicon and nitrogen, and has one or more chrome-based material film. The high transition metal content ensures electrical conductivity, preventing charge-up in the photomask production process, and also provides sufficient chemical stability to cleaning in photomask production. The light-shielding film has a good resistance to dry etching of the chrome-based material film in the presence of chlorine and oxygen, thus ensuring a high processing accuracy.
1. A photomask blank for producing a photomask having a transparent substrate provided thereon with a mask pattern of regions transparent to and regions substantially opaque to an exposure light, comprising:
a light-shielding film composed of a single layer made of a material containing a transition metal, silicon and nitrogen or a plurality of layers that include at least one layer made of a material containing a transition metal, silicon and nitrogen, and
one or more chrome-based material film;
wherein the material containing a transition metal, silicon and nitrogen has an atomic ratio of silicon to transition metal, expressed as silicon/transition metal, of at least 1:1 but less than 4:1, and has a nitrogen content of least 5 atom % but not more than 40 atom %.
2. The photomask blank of claim 1 , wherein the layer made of a material containing a transition metal, silicon and nitrogen has a combined amount of transition metal and silicon, as a proportion of the material making up the layer, of at least 60 atom %.
3. The photomask blank of claim 1 , wherein the chrome-based material film is formed in a side of the light-shielding film that is away from the transparent substrate.
4. The photomask blank of claim 3 , wherein the chrome-based material film forms part or all of an antireflective film.
5. The photomask blank of claim 3 , wherein the chrome-based material film is an etching mask film.
6. The photomask blank of claim 1 , wherein the chrome-based material film is formed between the transparent substrate and the light-shielding film.
7. The photomask blank of claim 6 , wherein the chrome-based material film is an etching stopper film.