Among flat panel display devices, an organic light emitting diode (OLED) display device has an advantage as a moving picture display medium regardless of the size of the device due to a high response time of 1 ms or less, low power consumption, a self emission characteristic, and a wide viewing angle. The OLED display device has also attracted attention as a next-generation flat panel display device because it can be manufactured at a low temperature by a simple process based on conventional semiconductor process technology.
Methods of forming a thin film of the flat panel display device or OLED display device are roughly classified into methods for a polymer device using a wet process and methods for a small molecular device using a deposition process according to the material and process to be used.
For example, an inkjet printing method among the methods of forming a polymer or small-molecular emitting layer has disadvantages in that materials suitable for forming organic layers other than the emitting layer are limited, and a structure for inkjet printing should be formed on a substrate.
When an emitting layer is formed by deposition, a separate metal mask is used. The size of the flat panel display device is directly proportional to the size of the metal mask. As the metal mask is increased in size, it is difficult to manufacture a large-sized device due to sagging of the metal mask.
FIG. 1 is a schematic cross-sectional view of a deposition apparatus including a deposition mask.
Referring to FIG. 1, to deposit a thin film of an OLED display device, for example, an organic layer including an emitting layer, using a mask 1, a frame 4 coupled to the mask is equipped at a location corresponding to a thin film deposition crucible 3 installed in a vacuum chamber 2, and a subject 5 on which a thin film will be formed is installed. A magnet unit 6 is operated so that the mask 1 supported by the frame 4 is closely in contact with the subject 5 on which the thin film will be formed. In this state, a material disposed in the thin film deposition crucible 3 during the operation of the thin film deposition crucible 3 is deposited on the subject 5.
However, as described above, in the formation of a thin film using a deposition apparatus having such a deposition mask, as a flat panel display device becomes larger, the deposition mask needs to be also increased in size. In this case, however, due to the sagging of the mask, alignment between the mask and the subject is difficult, and thus a large-sized device is also difficult to be manufactured.