Patent ID: 6998206

Claim:
A method of increasing the shelf life of a blank photomask substrate coated with a chemically amplified photoresist, said method comprising: selecting a chemically amplified photoresist comprising a modified phenolic polymer, and an onium salt-containing chemical amplifier; coating a photomask substrate with said chemically amplified photoresist; and post application baking said chemically amplified photoresist on said photomask substrate at a temperature ranging between about 84° C. and about 115° C. for a time period which provides stability of said baked blank photomask substrate while exposed to ambient atmosphere conditions in a clean room at room temperature, whereby after storage of said coated photomask substrate for a period of more than 2 hours, a difference in a subsequently generated photomask critical dimension feature is less than 20 nm compared with said feature generated immediately after application of said chemically amplified photoresist on said photomask substrate.