METHOD OF SELECTING PHOTOMASK BLANK SUBSTRATE FOR FORMING PHOTOMASK USED FOR EXPOSING PATTERNS HAVING REDUCED MINIMUM FEATURE SIZE

摘要

PURPOSE: A method of selecting a photomask blank substrate is provided to form a photomask used for exposing patterns having a reduced minimum feature size to high accuracy on a wafer substrate. CONSTITUTION: One or more layer including at least a masking layer or a phase shift layer is deposited on a top surface(1) of a photomask blank substrate to form a photomask blank. The deposited layer is patterned to form a photomask. The photomask is mounted in an exposure tool. A method of selecting the photomask blank substrate includes a simulating process, a determining process, and a selecting process. The simulating process is performed to simulate a change of shape on the top surface of the substrate before the deposition process when the photomask is mounted in the exposure tool. The determining process is performed to determine the shape on the top surface of the substrate before the change of shape when the photomask is mounted in the exposure tool. The selecting process is performed to select a substrate having the shape on the top surface before the deposition process.