Thin-film deposition mask assembly and method of fabricating organic light-emitting display panel using same

A thin-film deposition mask assembly, comprising:

• a first mask comprising a first base member having a plurality of openings provided in the first base member, each of the opening being spaced apart from each other;
• a first frame holding the first mask;
• a plurality of first openings disposed in odd columns included in the plurality of openings of the first mask;
• and
• a plurality of second openings disposed in even columns included in the plurality of openings of the first mask, the odd and even columns being arranged in a column direction;
• wherein a single second opening disposed in an nth even column, among the plurality of second openings, the second opening being disposed between two first openings arranged in a first direction corresponding to a row direction, the row direction being transverse to the column direction and disposed in at least one column of (n−1)th and (n+1)th columns, among the plurality of first openings, where n is a natural number equal to or greater than 2.