Photomask having a plurality of shielding layers

A photomask for mask patterning, comprising:

• a transparent layer comprising quartz;
• a molybdenum silicide (MoSi) layer overlying the transparent layer;
• a first shielding layer overlying the MoSi layer, the first shielding layer comprising a transition metal or a post transition metal, wherein the first shielding layer has a first thickness and a first optical density;
• and
• a second shielding layer overlying the first shielding layer and comprising chromium, wherein the second shielding layer has a second thickness less than one half of the first thickness and has a second optical density that is less than one half of the first optical density, and wherein an overall optical density of the first and second shielding layers is greater than 1.8.

A photomask for mask patterning, comprising:

• a transparent layer comprising quartz;
• a molybdenum silicide (MoSi) layer overlying the transparent layer;
• a first shielding layer overlying the MoSi layer, the first shielding layer having a first thickness and a first optical density;
• and
• a second shielding layer overlying the first shielding layer, the second shielding layer having a second thickness and a second optical density;
• wherein a thickness ratio of the first thickness to the second thickness is greater than 3:1, and an optical density ratio of the first optical density to the second optical density is greater than 4:1.