Next, a thin film encapsulation layer 300 may be formed to cover the lower dam 700 and the display unit 200. A concave portion C may be formed in thin film encapsulation layer 300 at a portion covering the lower dam 700. For example, as illustrated in FIG. 7A, when the thin film encapsulation layer 300 is formed to cover two lower dams 700, the thin film encapsulation layer 300 may be formed to be concavely curved between the two lower dams 700 spaced apart from each other by a certain distance. Thus, the thin film encapsulation layer 300 may include the concave portion C formed at a position between the two lower dams 700.

Next, referring to FIG. 7B, an upper dam 600 may be formed over the thin film encapsulation layer 300.

As described above, because the concave portion C is formed in the thin film encapsulation layer 300, the upper dam 600 may be easily formed. For example, as an alternative embodiment, two lower dams 700 spaced apart from each other may be formed, a concave portion C may be formed at a corresponding position between the two lower dams in the thin film encapsulation layer 300 covering the lower dam 700, and an upper dam 600 may be formed over the concave portion C. Because the concave portion C is formed to be curved concavely between the two lower dams 700, the upper dam 600 may be easily formed at a position of the concave portion C.

Next, referring to FIG. 7C, a buffer layer 350 may be formed over the thin film encapsulation layer 300, and the buffer layer 350 may not flow into the opening portion OP due to the upper dam 600.