Halftone mask, method of manufacturing the same, and method of manufacturing an array substrate using the same

A halftone mask includes a transparent substrate, a light-blocking layer, a first semi-transparent layer and a second semi-transparent layer. The transparent substrate includes a light-blocking area, a light-transmitting area, a first halftone area transmitting first light, and a second halftone area transmitting second light that is less than the first light. The light-blocking layer is formed in the light-blocking area to fully block light from being transmitted. The first and second semi-transparent layers are formed on the transparent substrate. At least one of the first and second semi-transparent layers is formed in the first halftone area, and the first and second semi-transparent layers are overlapped with each other on the second halftone area.