A partition is formed by the process including a step for providing a
sheet-like partition material that covers a display area and outside
thereof on the surface of the substrate, a step for providing a mask for
patterning that covers the display area and the outside thereof, so that
a pattern of the portion arranged outside of the display area of the mask
is a grid-like pattern, a step for patterning the partition material
covered partially with the mask by a sandblasting process, and a step for
baking the partition material after the patterning.