1. Field of the Invention
Embodiments of the present invention relate to a flexible substrate, a method of fabricating the same, and a thin film transistor (TFT) using the same. More particularly, embodiments of the present invention relate to a flexible substrate exhibiting reduced deformation during fabrication thereof.
2. Description of the Related Art
Flat panel display devices, e.g., liquid crystal display (LCD) devices, organic light emitting diode (OLED) display devices, and so forth, may include thin and lightweight display panels. For example, since the OLED display devices do not need a back light, the OLED display devices may be implemented in ultra-thin display devices. Flat panel display devices, e.g., OLED display devices, may also exhibit high brightness and a wide viewing angle.
A conventional flat panel display device may include a flexible substrate, e.g., to minimize alignment difficulties and/or damage to the substrate due to external impacts during manufacturing thereof. For example, a conventional flexible substrate may be formed of plastic or metal.
A conventional flexible substrate formed of plastic, however, cannot be used in a process for forming a TFT of polysilicon or in a high-temperature deposition process for forming an electrode or light emitting diode (LED) on the flexible substrate due to low thermal resistance. A conventional flexible substrate formed of metal, however, may be deformed during manufacturing thereof despite a relatively higher thermal resistance and flexibility as compared to the plastic substrate.
In particular, when, e.g., a TFT and/or a LED is formed on the conventional metal substrate, the metal substrate may include a buffer layer to insulate the TFT and/or the LED from the metal substrate. However, since a difference of coefficients of thermal expansion of the metal substrate, i.e., a conductive material, and the buffer layer, i.e., an insulating material, is substantially large, an excessive residual stress may be generated in the buffer layer, thereby deforming, e.g., bending, the metal substrate attached thereto. Deformation of the metal substrate may cause delamination of the buffer layer from the metal substrate, thereby deteriorating the insulating properties of the buffer layer.
USPTO Backgrounds
USPTO Backgrounds