Method of manufacturing shadow mask

A method of manufacturing a shadow mask having first and second major surfaces and a plurality of apertures, said apertures having different opening sizes on said first and second major surfaces, comprising the steps of:

• (i) forming photoresist layers on said first and second major surfaces of a metal substrate, respectively;
• (ii) exposing and developing said photoresist layers of said first and second major surfaces to form a first opening resist pattern layer on said first major surface, and to form a second opening resist pattern layer which is different in size from said first opening resist pattern on said second major surface;
• (iii) etching the first major surface to form first openings;
• (iv) after the first opening resist pattern layer is removed, applying an etching resistive agent composition containing an acrylic resin, casein, and a leveling agent to said first major surface to form an etching resistive layer;
• (v) etching the second major surface to form second openings which are different from said first openings in size;
• and
• (vi) removing said etching resistive layer and the second opening resist pattern layer, thereby forming said apertures, each having said first and second openings for communicating with each other.