Abstract: An etching process is disclosed which is suited for manufacturing color selecting mechanisms in wide scope of specifications without need of complicated process of manufacture.The etching process comprises the steps of (a) forming an etching resist layer (20) on the front surface (10A) of a work (10) and also forming a protective layer (12) on the back surface (10B), (b) patterning the etching resist layer (12) to form a first opening (22) and a second opening (24) smaller than and near the first opening, and (c) etching the work to form a slit zone (32) under the first opening (22) and a recess (34) under the second opening (24) while removing at least a portion (10C) of the work spacing apart the slit zone (32) and the recess (34), thereby forming an electron beam passage slit (30) having a greater opening area defined on the side of the front surface (10A) by the slit zone (32) and the recess (34). (See FIG.