Vapor deposition mask substrate, vapor deposition mask substrate manufacturing method, vapor deposition mask manufacturing method, and display device manufacturing method

A vapor deposition mask substrate, comprising:

• a metal sheet that has a shape of a strip and is configured to be etched to include a plurality of holes and used to manufacture a vapor deposition mask, wherein
• the metal sheet has a longitudinal direction and a width direction,
• the metal sheet has shapes in the width direction that are taken at different positions in the longitudinal direction of the metal sheet and differ from one another,
• each of the shapes comprises an undulated shape including protrusions and depressions repeating in the width direction of the metal sheet,
• a length in the width direction of a surface of the metal sheet is a surface distance,
• a minimum value of surface distances at different positions in the longitudinal direction of the metal sheet is a minimum surface distance,
• a ratio of a difference between a surface distance and the minimum surface distance to the minimum surface distance is an elongation difference ratio in the width direction, and
• a maximum value of elongation difference ratios is less than or equal to 2×10−5.