Thin film encapsulation for a flat panel display device and a method of manufacturing the thin film encapsulation structure. The thin film encapsulation structure of the flat panel display device includes thin film layers covering a display unit formed on a substrate, wherein the thin film layers comprise a plurality of inorganic layers and a hexamethyldisiloxane (HMDSO) layer interposed between the inorganic layers. Accordingly, as multiple layers of the thin film encapsulation structure may be formed in a single chamber, the manufacturing process may be simplified, and also, as the HMDSO layer, which is flexible, absorbs stresses, a risk of cracks occurring may also be reduced.