Active solid-state devices (e.g. – transistors – solid-state diode – Incoherent light emitter structure
Reexamination Certificate
2001-07-11
2004-12-07
Blum, David S. (Department: 2813)
Active solid-state devices (e.g., transistors, solid-state diode
Incoherent light emitter structure
Reexamination Certificate
active
06828588
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a protective film for a flat panel display (FPD) such as a plasma display panel (PDP), a plasma addressed liquid crystal display (PALC), and the like and an FPD in which the protective film is used, a vapor deposition material suitable for forming a protective film for FPD and its production method, and a device for manufacturing an FPD protective film.
2. Description of Related Art
During the past several years, there has been considerable activity in the research and development as well as practical application of liquid crystal displays (LCD) and various other types of flat displays, and production of these displays is also increasing rapidly. There has recently also been growing activity in the development and practical application of color plasma display panels (PDP). PDP are easily applied to large screens, and are the easiest way to achieve large-screen wall-mounted televisions for Hi-Vision applications, and prototypes of PDP offering a diagonal size of 40 inches have already been developed. In the case of FPD, which include these PDP, the glass dielectric layer is directly exposed to electrical discharge, and the surface of the dielectric layer changes due to sputtering of ion collisions resulting in a rise in the discharge starting voltage. Consequently, various oxides having a high heat of sublimation have been used as protective films.
In the past, known examples of depositing this protective film included methods involving the formation of an FPD protective film using a vacuum process such as electron beam vapor deposition, sputtering and ion plating. In the case of electron beam vapor deposition and ion plating, the vapor deposition material serving as the raw material for forming the protective film, and the FPD on which the protective film is formed, are placed in a vacuum container, the vapor deposition material is heated under a high vacuum, or evaporated using an electron beam or plasma, and the vapor is agglutinated in the form of a thin film on the surface of the FPD.
On the other hand, since a PDP protective film is in direct contact with the discharge space, it serves as the key material for fulfilling the most important role for discharge characteristics, and an MgO film was used in the past due to its high secondary electron discharge capabilities and superior sputtering resistance, light transmission and insulating properties.
However, if this MgO film is exposed to the atmosphere during the course of processing, it deteriorates easily as a result of reacting with CO
2
and H
2
O. Therefore, it is known that degassing exhaust treatment over a long period of time while heating in a vacuum after sealing the film on the panel is required in order to obtain the inherent characteristics of MgO (see, for example, Sato, ed., Current Plasma Display Production Technology (Press Journal Co., Ltd.): p. 118-123 and p. 291-295 (1997)). According to this, impurity gases such as H
2
O, H
2
, O
2
, CO, CO
2
and N
2
have a detrimental effect on PDP discharge characteristics and composite materials in the panel, and contamination by CO
2
in particular can worsen panel characteristics beyond recovery.
Consequently, the coating of the MgO surface with another material having low moisture permeability has been proposed in order to prevent deterioration of MgO (Japanese Unexamined Patent Application, First Publication No. 10-149767, W. T. Lee et al.: “LaF
3
coated MgO protecting layer in AC-Plasma Display Panels”, IDW '99, p. 72-75).
The above Japanese Unexamined Patent Application, First Publication No. 10-149767 proposes a PDP production method consisting of forming a protective film followed by temporarily forming a protective film having a low moisture permeability on this protective film, and then removing that temporary protective film. According to this method, during production of the PDP, since the surface of the protective film is protected by a temporary protective film, a deteriorated layer is not formed on the surface of the protective film. As a result, in addition to being able to obtain a protective film with satisfactory discharge characteristics, thermal decomposition treatment of a deteriorated layer on the protective film is not required.
In addition, in the above reference of W. T. Lee et al, together with suppressing deterioration of the MgO protective film by coating LaF
3
having low moisture permeability onto an MgO protective film, it is proposed that higher secondary electron discharge characteristics and lower discharge characteristics can be realized.
However, in the production methods described in the above-mentioned Japanese Unexamined Patent Application, First Publication No. 10-149767 and the reference of W. T. Lee et al. of the prior art, it is difficult to conform the temporary protective film with the protective film when forming the temporary protective film, and there are cases in which cracks may form in the temporary protective film or the temporary protective film may peel off, thus making the effect of the temporary protective for preventing deterioration of the protective film inadequate. In order to improve this, although a method was considered in which a temporary protective film is laminated in a thick layer onto a protective film, in this method, there was the problem of a large amount of impurities (decomposition products of the temporary protective film) being formed during removal of the temporary protective film.
Moreover, in the above reference of W. T. Lee et al., 5-90 nm of LaF
3
are laminated onto MgO and in this double layer structure, when the LaF
3
of the upper layer film is removed by sputtering, there was the problem of an adequate lifetime being unable to be obtained due to sudden changes in the discharge voltage
In addition, alkaline earth metal oxides are used as vapor deposition materials that serve as the raw materials for forming a superior protective film as described above.
However, similar to MgO films, if these alkaline earth metal oxides are exposed to the atmosphere before being used as vapor deposition materials, they are easily deteriorated as a result of reacting with CO
2
and H
2
O. Consequently, it is known that, after placing vapor deposition materials comprised of alkaline earth metal oxides in a vacuum container, degassing exhaust treatment for a long period of time while heating in a vacuum is required. Namely, if degassing exhaust treatment is not performed for a comparative long period of time, impurity gases such as H
2
O, H
2
, O
2
, CO, CO
2
and N
2
generated in large amounts from the deteriorated surface of the vapor deposition material cause problems in the characteristics of the resulting protective film.
In addition, as an example of a manufacturing device for producing a protective film as described above, a manufacturing device for FPD protective films is disclosed comprising coupling a loading chamber that loads substrate onto a line, a heating chamber that heats the substrates, a film formation chamber in which a film body is formed on one surface of the substrates, a cooling chamber that cools the substrates, and an unloading chamber that unloads substrates from the line, without exposing them to the atmosphere (inline system), whereby a protective film is formed by electron beam vapor deposition and so forth at a predetermined region on the substrates (see, for example, Ulvac Technical Journal, No. 46, pp. 8-13 (1997), 7
th
Fine Process Technology Japan '97 Seminar preliminary collection of papers, D5, pp. 35-42 (1997)). In a manufacturing device for FPD protective film composed in this manner, since the process is carried out from loading to unloading of substrates without exposing the process to the atmosphere, improved productivity and conservation of space can be realized.
On the other hand, as examples of an apparatus for treating materials with a gaseous fluoridation agent, a dry etching apparatus that performs treatment with a mixed gas of H
F
and H
2
O for removi
Kuromitsu Yoshirou
Sakurai Hideaki
Blum David S.
Mitsubishi Materials Corporation
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