After the attachment process, a substrate etching process, in which the outer surfaces of the upper and lower substrates are etched to reduce the thickness of the substrates, is performed according to the desired lightening of the substrate. However, since a main seal pattern can be damaged during the substrate etching process, a method of preventing the damage, in which a sub-seal pattern is formed, is suggested. However, if a plurality of unit liquid crystal cells is formed on one substrate, deterioration resulting from a low margin for the sub-seal patterns can occur so that a yield is decreased. In an embodiment according to the present invention, damage of the main seal pattern from the etching solution during the substrate etching process is prevented by the formation of the sub-seal patterns in the exterior of the main seal pattern, and air of the cell interior are easily vented due to the air vent portion having a proper seal pattern for ventilation. Therefore, the yields of the unit liquid crystal cells are increased.