According to some embodiments, the concave-convex pattern 63 may include the first pair of inclined interfaces I1, each of which is inclined to face each other, and a second pair of inclined interfaces I2, each of which is inclined to face each other between the first pair of inclined interfaces I1, each of which is inclined to face each other. Here, that each of the first pair of inclined interfaces 1 and the second pair of inclined interfaces I2 are inclined to face other may denote that each of the first pair of inclined interfaces I1 and the second pair of inclined interfaces I2 may have inclinations approaching each other from a lower location to an upper location in the thickness direction (the third direction Z3) of the first plate P1. Here, the first pair of inclined interfaces I1 may include an interface inclined by an inclination of about 45 degrees in the second direction Z2 and an interface inclined by an inclination of about ?45 degrees in the second direction Z2, and the second pair of inclined interfaces I2 may include inclined interfaces having a greater downward inclination toward the second plate P2 than the first pair of inclined interfaces. For example, the second pair of inclined interfaces I2 may include the inclined interfaces having greater inclinations than 45 degrees and ?45 degrees. According to some embodiments, while each of the first pair of inclined interfaces I1 and each of the second pair of inclined interfaces I2 may have the inclination approaching each other from the lower location toward the upper location in the direction opposite to the second plate P2, the second pair of inclined interfaces I2 may have a greater inclination toward the second plate P2 than the first pair of inclined interfaces I1.