A color organic EL (i.e., electroluminescence) display constituted by interposing a gas barrier layer between an organic EL (electroluminescence) structural body and a color filter is well-known.
This sort of color organic EL display is equipped with such a structure that a color filter layer, a gas barrier layer, and an organic EL structural body have been successively stacked on a substrate.
Specifically, when an organic EL structural body for emitting white light is combined with a color filter, the below-mentioned structure of such a color organic EL display is known. That is, a color filter layer, an overcoat layer, a gas barrier layer, and an organic EL structural body element are successively stacked on a transparent substrate, while the organic EL structural body element emits white light.
In this color organic EL display, the gas barrier layer is provided to prevent difficulties such as dark spots of the white light emitting organic EL structural body and lowering of a luminous efficiency thereof. These difficulties are caused by water contents and the like, which are volatilized from the color filter layer and the overcoat layer, which are made of resin.
Accordingly, as to the gas barrier layer, pin-holeless characteristics are required, and superior step coverage thereof is required. In addition to the above-described performance, other performance such as transparent characteristics and flat characteristics of surfaces is required.
Conventionally, as examples of gas barrier layers, one gas barrier layer has been proposed which contains a silicon oxide and is manufactured by executing a sputtering film forming method. For example, Japanese Laid-open Patent Application No. Hei-11-260562 (which corresponds to EP 1115269-A1) discloses the structure. Also, another gas barrier layer has been proposed in which an insulating inorganic oxide layer is arranged as the gas barrier layer of a color converting element (CCM). For example, Japanese Laid-open Patent Application No. Hei-8-279394 (which corresponds to U.S. Pat. No. 5,909,081) discloses this structure.
However, pin-holes are not considered in view of gas barrier characteristics, as to these conventional gas barrier layers, so that dark spots are easily produced in pixels, and such pixels which cannot maintain desirable light emitting characteristics of organic EL elements are readily produced.
As measures capable of solving such pin-hole problems occurred in these gas barrier layers, one measure has been proposed in which while a gas barrier layer is formed in a multilayer structure, cleaning steps are carried out among film forming steps for these plural gas barrier layers. For instance, Japanese Laid-open patent Application No. 2003-229271 discloses this structure. Another measure has been proposed in which while a gas barrier layer is formed in a multilayer structure, resin layers are distributed to the respective gas barrier layers. For instance, Japanese Laid-open Patent Application No. 2003-282239 discloses the structure.
Also, as the pin-hole measures, one measure has been proposed in which a gas barrier layer is formed by a plasma CVD method (P-CVD method), while this P-CVD method is capable of forming a dense film, as compared with a sputtering method which corresponds to a general-purpose film forming method for a gas barrier layer. For example, Japanese Laid-open Patent Application No. 2004-39468 discloses the structure.
However, the pin-hole measures described in the above documents own problems as to productivity and cost aspects, since the structures of the gas barrier layers and the manufacturing processes thereof are complex.
Also, in the gas barrier layer manufactured by employing the P-CVD method, when the gas barrier layer is formed by way of the P-CVD method, the film forming operations are carried out at a relatively low temperature, since heat resistance characteristics as to the color filter layer and the overcoat layer are considered, which are provided under the gas barrier layer. In this film forming operation, since dense characteristics of these films are deteriorated, gas barrier characteristics thereof are deteriorated. As a result, these layer structures must be replaced by other stacked layer structures, or the film thicknesses of these layers must be made thicker, so that the problem as to the productivity still remains, and thus, the manufacturing cost is increased.