Photomask blank, photomask, and methods of manufacturing the same

A photomask blank for fabricating a phase shift mask having a light-transmissive substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light,

• wherein said phase shift part is a phase shift film formed on an upper surface of said light-transmissive substrate and adapted to give a predetermined phase change amount to said transmitted exposure light,
• said photomask blank comprising:
• a light-shielding part formed in a peripheral area around a transfer pattern area of a surface of said phase shift film and adapted to shield exposure light;
• and
• an etching mask film formed in the transfer pattern area of the surface of said phase shift film and made of a material being substantially dry-etchable with a chlorine-based gas, but not substantially dry-etchable with a fluorine-based gas, said etching mask film serving as an etching mask at least until a transfer pattern is formed in said phase shift film by dry etching with a fluorine-based gas.

A method of manufacturing a phase shift mask having a light-transmissive substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light, said method comprising:

• forming a light-shielding film on an upper surface of said light-transmissive substrate, said light-shielding film adapted to shield exposure light;
• dry-etching said light-shielding film using a resist film pattern as a mask, thereby forming a light-shielding part in a peripheral area around a transfer pattern area;
• forming an etching mask film on the upper surface of said light-transmissive substrate after said step of dry-etching;
• dry-etching said etching mask film using a resist film pattern as a mask, thereby forming an etching mask film pattern;
• and
• dry-etching said light-transmissive substrate using said etching mask film pattern as a mask, thereby forming said phase shift part by digging down said light-transmissive substrate from the upper surface thereof to a digging depth adapted to produce said predetermined phase difference.

A method of manufacturing a phase shift mask having a light-transmissive substrate provided with a phase shift part adapted to give a predetermined phase difference to transmitted exposure light, said method comprising:

• forming a phase shift film on an upper surface of said light-transmissive substrate, said phase shift film adapted to give a predetermined phase change amount to transmitted exposure light;
• forming a light-shielding film on an upper surface of said phase shift film, said light-shielding film adapted to shield exposure light;
• dry-etching said light-shielding film using a resist film pattern as a mask, thereby forming a light-shielding part in a peripheral area around a transfer pattern area;
• forming an etching mask film on the upper surface of said phase shift film after said step of dry-etching;
• dry-etching said etching mask film using a resist film pattern as a mask, thereby forming an etching mask film pattern;
• and
• dry-etching said phase shift film using said etching mask film pattern as a mask, thereby forming said phase shift part.