Display device

An organic EL display device has a TFT formed on the substrate, and an organic EL layer formed on the TFT. A protective layer is formed on the organic EL layer, and a first barrier layer which contains AlOx is formed between the substrate and the TFT.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent Application No. 2016-100485 filed on May 19, 2016, the content of which is hereby incorporated by reference into this application.

BACKGROUND OF THE INVENTION

(1) Field of the Invention

The present invention relates to a display device, and more particularly, to a flexible display device which allows the substrate to be bent. The present invention further relates to the flexible display device configured to employ an oxide semiconductor for the TFT.

(2) Description of the Related Art

The organic EL display device and the liquid crystal display device may be configured to reduce the display device thickness so as to be used while being flexibly bent. In this case, the thin glass or the thin resin may be used for forming the substrate that constitutes the device. The organic EL display device which employs no backlight is more suitable for thinning.

The liquid crystal display device or the organic EL display device has a layer structure including a large number of layers of various types, for example, the conductive layer, the inorganic insulating layer, the organic insulating layer, the semiconductor layer, and the like Laminating layers each exhibiting different thermal expansion coefficient may cause stress in the film, leading to crack and separation in the thin film.

Japanese Unexamined Patent Application Publication No. 2004-317649 discloses the laminated structure obtained by interposing SiOx2and Cr2O3films between the organic insulating film and the ITO (Indium Tin Oxide) for the purpose of alleviating the interlayer stress resulting from formation of the organic insulating film and the ITO.

SUMMARY OF THE INVENTION

The TFT (Thin Film Transistor) is employed for controlling signals applied to the pixel. Such materials as a-Si (Amorphous-Si) and Poly-Si have been used for forming the TFT. Meanwhile, recently, use of the TFT constituted by the oxide semiconductor featured by small leak current has been receiving a lot of attention because the pixel electrode voltage can be stably retained for a prolonged period of time. However, the oxide semiconductor is weak to moisture and hydrogen.

Meanwhile, the organic EL material for forming the light emitting layer of the organic EL display device will be decomposed in the presence of moisture, resulting in deteriorated performance. Accordingly, the organic EL layer has to be protected from moisture in order to ensure operating life. The barrier against moisture is implemented by using the laminated film of SiOx (denoting SiO2in the description as the basic structure, generally indicating deviation from stoichiometry of x=2), or SiNx (denoting Si3N4in the description as the basic structure, generally indicating deviation from the stoichiometry of x=4/3).

The use of the laminated film made of SiOx or SiNx is still insufficient to provide the barrier performance against the moisture and hydrogen. It is an object of the present invention to provide the long-life display device configured to protect the TFT and the organic EL layer from moisture and hydrogen.

The present invention may be exemplified by the structure as described below.

(1) An organic EL display device includes a TFT formed on a substrate, and an organic EL layer formed on the TFT. A protective layer is formed on the organic EL layer, and a first barrier layer which contains AlOx is formed between the substrate and the TFT
(2) In the organic EL display device as described in (1), the first barrier layer is formed into a laminated structure of a first AlOx and a second AlOx.
(3) A liquid crystal display device includes a TFT and a pixel electrode formed on a first substrate, a counter substrate disposed opposite to the first substrate, and a liquid crystal interposed between the first substrate and the second substrate. A first barrier layer which contains AlOx is formed between the TFT and the first substrate.
(4) In the liquid crystal display device as described in (3), the first barrier layer is formed into a laminated structure of a first AlOx and a second AlOx.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in detail referring to the following embodiments.

First Embodiment

FIG. 1is a plan view of the organic EL display device to which the present invention is applied. The organic EL display device according to the present invention is configured to be flexibly bent. Referring toFIG. 1, the organic EL display device includes a display region1000and a terminal part150. A polarizing plate500is bonded to the display region1000for antireflection purpose. A flexible wiring substrate300is connected to the terminal part150for supplying power and signals to the organic EL display device. A driver IC400is also connected to the terminal part150for driving the organic EL display device.

FIG. 2is a sectional view taken along line A-A ofFIG. 1. The display region and the terminal part are formed on a polyimide substrate100. The polyimide substrate100has a thickness from 10 μm to 20 μm, which can be flexibly bent. Since the polyimide substrate100is thin to make its shape unstable, and mechanical strength insufficient, a first protective film1is applied to a back surface of the substrate. The first protective film1is made of PET (polyethylene terephthalate), or an acrylic resin, having a thickness of approximately 0.1 mm.

Referring toFIG. 2, an array layer having a light emitting layer is formed on the polyimide substrate100, on which the polarizing plate500is disposed to cover the layer. The organic EL display device of top emission type includes a reflection electrode so as to reflect external light. The polarizing plate500serves to help the user view the screen by preventing reflection of the external light.

FIG. 3is a sectional view showing structure of the display region of the organic EL display device of top emission type according to the present invention.FIG. 3omits the first protective film1as shown inFIG. 2. Referring toFIG. 3, a first barrier layer10made of AlOx, or the like is formed on the polyimide substrate100having the thickness ranging from 10 μm to 20 μm. In the description, the AlOx is regarded as the term having Al2O3as the basic structure, which generally refers to deviation from the stoichiometry of x=1.5. The first barrier layer10serves to prevent external penetration of moisture through the polyimide substrate100, or penetration of moisture or hydrogen generated in the polyimide substrate100by itself.

A base film101made of SiOx, SiNx, or the like is formed on the first barrier layer10through the CVD. A semiconductor layer102is formed on the base film101. The semiconductor layer102as shown inFIG. 3is constituted by the oxide semiconductor. The oxide semiconductor may be, for example, a-IGZO (amorphous Indium Gallium Zinc Oxide), or the like. The oxide semiconductor is featured by small leak current. Meanwhile, the Poly-Si semiconductor layer may be used for forming the TFT as shown inFIG. 3. In this case, the semiconductor layer102can be primarily produced by forming the a-Si through the CVD first, which is then converted into Poly-Si through excimer laser.

A gate insulating film103made of SiOx derived from TEOS (tetraethoxysilane) through the CVD is formed while covering the semiconductor layer102. A gate electrode104is formed on the gate insulating film103. Thereafter, the part of the semiconductor layer102besides the region corresponding to the gate electrode104is formed into a conductive layer through ion implantation. The part of the semiconductor layer102, which corresponds to the gate electrode104becomes a channel part1021.

An interlayer insulating film105is made of SiNx through the CVD while covering the gate electrode104. A second barrier layer20made of AlOx is formed on the interlayer insulating film105. The second barrier layer20serves to protect the TFT constituted by the oxide semiconductor from moisture and hydrogen, and to protect an organic EL layer112from moisture, hydrogen, and the like from the polyimide substrate100.

Then through holes are formed in the second barrier layer20, the interlayer insulating film105, and the gate insulating film103so as to connect a drain electrode106and a source electrode107. Referring toFIG. 3, an organic passivation film108is formed while covering the drain electrode106, the source electrode107, and the second barrier layer20. The organic passivation film108serving as a flattening film is made thick in the range from 2 μm to 3 μm. For example, the acrylic resin may be used for forming the organic passivation film108.

A reflection electrode109is formed on the organic passivation film108, on which a lower electrode110is formed as an anode, which is made of transparent conductive film such as ITO. The Al alloy with high reflectivity is used for forming the reflection electrode109. The reflection electrode109is connected to the source electrode107of the TFT via the through hole formed in the organic passivation film108.

A bank111made of acryl or the like is formed around the lower electrode110. The bank111is provided in order to prevent conduction failure caused by step-cut of the organic EL layer112including the light emitting layer and an upper electrode113, which are formed in the subsequent step. The bank111is formed by applying a transparent resin such as the acrylic resin over the entire surface, and forming the hole in the part corresponding to the lower electrode110for taking light from the organic EL layer.

Referring toFIG. 3, the organic EL layer112formed on the lower electrode110is constituted by an electron injection layer, an electron transport layer, a light emitting layer, a hole transport layer, a hole injection layer, and the like. The upper electrode113as a cathode formed on the organic EL layer112is constituted by an IZO (Indium Zinc Oxide), an ITO (Indium Tin Oxide), and the like as the transparent conductive film. It may also be constituted by a thin metal film such as silver.

Then, a protective layer114made of SiN through the CVD is formed on the upper electrode113for the purpose of preventing penetration of moisture from the side of the upper electrode113. As the organic EL layer112is weak to heat, the protective layer114is formed through the CVD at low temperature of approximately 100° C.

A third barrier layer30made of AlOx or the like is formed while covering the protective layer114. The third barrier layer30serves to protect the organic EL layer112from moisture which penetrates the polarizing plate500and the like, together with the protective layer114.

The polarizing plate500is bonded with an adhesive material501to cover the third barrier layer30. The polarizing plate500serves to prevent reflection of external light. Any other type of protective layer or the protective film may be formed between the polarizing plate500and the third barrier layer30depending on the product type.

FIG. 4is a sectional view of the part around the first barrier layer10as shown inFIG. 3. Referring toFIG. 4, the first barrier layer10is formed on the polyimide substrate100. The polyimide substrate100which contains moisture may become the hydrogen source. The polyimide has the property that is likely to allow moisture penetration. In order to block the above-described moisture and hydrogen, the first barrier layer10made of AlOx is provided. The dense AlOx exhibiting high block performance with thickness from approximately 30 nm to 80 nm may provide sufficient block effect. The first barrier layer10made of AlOx as shown inFIG. 4is derived from sputtering.

Referring toFIG. 3, the second barrier layer20is formed on the interlayer insulating film105made of SiN, and the third barrier layer30is formed on the protective layer114made of SiN. Although each contact layer of the second barrier layer20and the third barrier layer30is different from that of the first barrier layer10, such layer serves to prevent moisture and hydrogen from externally reaching the TFT and the organic EL layer.

Generally, AC sputtering is employed for forming AlOx. The film formed through the AC sputtering will grow until the film stress reaches magnitude of GPa (Giga Pascal). The aforementioned state may bend the substrate asFIG. 5schematically shows. Bending of a large mother substrate4000upon sputtering of AlOx may cause the serious problem. The largely bent mother substrate4000is no longer available for the manufacturing process.

The DC sputtering may reduce the film stress, but fail to increase the film thickness of AlOx. Meanwhile, the AlOx formed through the process of atomic deposition layer (ADL) may reduce the film stress, but exhibit the low film production rate.

In order to solve the aforementioned disadvantage, the present invention is configured to produce the first barrier layer10by laminating the first AlOx11and the second AlOx12each having different film quality as shown inFIG. 6. The first AlOx11is produced through sputtering at the low H2O pressure, and the AlOx12as shown inFIG. 2is produced at the H2O pressure higher than the pressure at which the first AlOx is produced. The first AlOx11and the second AlOx12are produced so that the resultant films exhibit stress signs opposite to each other. This makes it possible to lower the overall stress of the barrier layer10.

FIG. 7is a graph indicating the relationship between the H2O pressure upon sputtering and the film stress of the produced AlOx film. As shown inFIG. 7, the x-axis denotes the H2O pressure upon sputtering, and the y-axis denotes the film stress of the produced AlOx film. Referring toFIG. 7, as the H2O pressure becomes higher, the sign of the film stress is switched from negative to positive.

AsFIG. 7shows, the film stress becomes zero at the H2O pressure of approximately 2×104Pa. In other words, from a limited view point of the film stress, the film produced through sputtering at the H2O pressure of approximately 2×10−4Pa is available. The AlOx film quality may vary depending on the H2O pressure in sputtering. Specifically, the lower the H2O pressure becomes, the denser the film may be obtained. The AlOx derived from sputtering at the H2O pressure of approximately 2×10−4Pa may fail to exhibit sufficient barrier property.

The present invention allows the use of the laminated structure constituted by laminating the first AlOx with high barrier property derived from sputtering at low H2O pressure, and the second AlOx derived from sputtering at the H2O pressure higher than the one at which the first AlOx is produced. This makes it possible to produce the barrier layer constituted by the AlOx with lower stress while retaining excellent barrier property.

As the film stress of the second AlOx has its sign opposite to that of the first AlOx, the overall film stress of the laminated film constituted by the first AlOx and the second AlOx may be regarded as being small Because of high barrier property, the first AlOx becomes the first barrier layer with high barrier property.

For example, asFIG. 7shows, the H2O pressure is set to P1(approximately 9×10−6Pa) for forming the first AlOx, and the H2O pressure is set to P2(approximately 4×10−4Pa) for forming the second AlOx so that values of the film stress of the first AlOx11and the second AlOx11become −200 MPa and 180 MPa, respectively. The overall film stress of the first barrier layer10may be made very small. This makes it possible to prevent warpage of the substrate. The first AlOx11is allowed to impart high barrier property to the first barrier layer10as a whole.

There is a correlation between density and refractive index of the AlOx film. That is, as the film becomes denser, the refractive index becomes higher.FIG. 8is a graph showing the relationship between the H2O pressure upon sputtering of the AlOx, and the refractive index of the produced AlOx. Specifically, the film quality of the AlOx may be evaluated by measuring the refractive index of the produced AlOx film. Such marks as ◯, Δ, X, □ shown inFIGS. 7 and 8represent different sample production lots.

Referring toFIG. 6, the first AlOx11is 10 nm thick, and the second AlOx12is 10 nm thick so that the overall thickness of the first barrier layer10is 50 nm. The laminated structure ofFIG. 6is a mere example, and accordingly, it is possible to set each film thickness to the value besides 10 nm. It is also possible to increase the number of layers to be more than five, or decrease the number of layers. Preferably, the total number of layers is an odd number, and each of the outer layers is constituted by the first AlOx11.

The film with laminated structure constituted by the first AlOx11and the second AlOx12as shown inFIG. 6may be easily produced. That is, the AlOx is produced through reactive sputtering using gas such as oxygen and Ar while setting Al as the target. Each H2O pressure in sputtering may be varied upon production of the first AlOx and the second AlOx.

According to the embodiment, the H2O pressure is controlled to change the AlOx film property. However, it is possible to introduce hydrogen bond to the AlOx film by using alkane such as hydrogen and methane, resulting in similar effects to those derived from the embodiment.

FIG. 9shows structure of the part around the first barrier layer10as shown inFIG. 3. The first barrier layer10has been explained referring toFIG. 6. The base film101formed on the first barrier layer10has a laminated structure constituted by SiOx (50 nm), SiNx (50 nm), SiOx (300 nm), for example.

The layer of the part around the first barrier layer10may have any other structure as shown inFIG. 10, for example. AsFIG. 10shows, the first barrier layer10is sandwiched between upper and lower layer sets of SiOx (50 nm), SiNx (50 nm), and SiOx (300 nm). The aforementioned structure may improve the film quality of the first AlOx11of the first barrier layer10. The SiOx layer and SiNx layer may have any other structures with respect to thickness and arrangement with no limitation to those shown inFIGS. 9 and 10.

The description of the present invention has been made with respect to the first barrier layer10as shown inFIG. 3. This applies to both the second barrier layer20and the third barrier layer30.

Second Embodiment

FIG. 11is a sectional view showing the structure of the first barrier layer10according to the second embodiment. The first barrier layer10as shown inFIG. 11has the laminated structure constituted by layers of the first AlOx11and an Al13. Specifically, this embodiment is different from the first embodiment in that the second AlOx12as shown inFIG. 6is replaced with the Al13. AsFIG. 11shows, each of odd-numbered layers is formed as the AlOx11, and each of even-numbered layers is formed as the Al13.

The film stress of the odd-numbered AlOx11will be absorbed by the even-numbered Al13so as to reduce the film stress of the first barrier layer10as a whole. The Al13formed adjacent to the AlOx11may further density the film quality of the sputtered AlOx.

The film having the laminated structure constituted by the AlOx11and Al13as shown inFIG. 11may be easily produced. Specifically, the AlOx11is produced by the reactive sputtering process using such gas as oxygen and Ar while setting Al as the target, and the Al13is produced using such gas as Ar while setting Al as the target. Accordingly, the film with the laminated structure may be produced by using different kind of gas upon formation of the respective films.

The Al layer13which exists in the structure of the barrier layer as shown inFIG. 11may make light transmission difficult. Therefore, the structure as shown inFIG. 11may be applied to the first barrier layer10and the second barrier layer20, but have difficulty in application to the third barrier layer30.

Referring toFIG. 11, for example, each film thickness of the first AlOx11and the Al13is 10 nm, and the film has the five-layered structure. However, the film thickness and the number of layers do not have to be limited to those shown inFIG. 11. The embodiment provides another advantage that the conductive layer of the Al13may be used in the process for antistatic purpose.

The embodiment has another advantage of automatically preventing electrification of the sputtering chamber owing to the conductive film formed therein on a regular basis. Specifically, the sputtering apparatus will accumulate static electricity therein as only the insulating film sputtering proceeds, resulting in damage to the product. For this reason, the sputtering apparatus is required to execute the conductive film sputtering process on the regular basis for preventing electrification inside the apparatus. The film formation according to the embodiment includes the process for forming the conductive film on the regular basis. Therefore, addition of the conductive film sputtering process is not necessary.

As described above, this embodiment is capable of protecting the TFT and the organic EL layer from moisture and hydrogen, and preventing warpage of the substrate simultaneously.

Third Embodiment

FIG. 12is a sectional view showing the present embodiment, specifically, in the case that the TFT of the organic EL display device is of bottom gate type. Referring toFIG. 12, the first barrier layer10made of AlOx or the like is formed on the polyimide substrate100. The base film101is formed on the first barrier layer10. The gate electrode104is formed on the base film101, and the gate insulating film103is formed while covering the gate electrode. The semiconductor layer102constituted by the oxide semiconductor or a-Si is formed on the gate insulating film103at the part corresponding to the gate electrode104.

The drain electrode106and the source electrode107are connected to the semiconductor layer102. An inorganic passivation film40made of SiN or the like is formed while covering the semiconductor layer102, the drain electrode106, and the source electrode107. The second barrier layer20made of AlOx or the like is formed on the inorganic passivation film40. The organic passivation film108is formed on the second barrier layer20, and the reflection electrode109is formed on the organic passivation film108. The reflection electrode109is connected to the source electrode107of the TFT via the through hole. The subsequent process is the same as the one as shown inFIG. 3.

The first barrier layer10as shown inFIG. 12has the same structure as the one described in the first embodiment referring toFIGS. 4 to 10, orFIGS. 6 to 10. In other words, the present invention may be applied to the TFT of bottom gate type so as to ensure lessening of the influence of moisture and hydrogen on the organic EL layer112, the TFT, and the like, and further ensure prevention of warpage of the substrate100.

Each of the second barrier layer20and the third barrier layer30as shown inFIG. 12has the same structure as the one described in the first embodiment. The laminated structure constituted by AlOx and Al as shown inFIG. 11according to the second embodiment may be applied to the present embodiment.

Fourth Embodiment

The present invention is applicable to the liquid crystal display device.FIG. 13is a plan view of the liquid crystal display device. Referring toFIG. 13, the display region1000is formed on a counter substrate200which faces the TFT substrate100, and an upper polarizing plate510is disposed while covering the display region1000. The terminal part150is connected to the driver IC400and the flexible wiring substrate300.

FIG. 14is a sectional view taken along line B-B ofFIG. 13. Referring toFIG. 14, the TFT substrate100and the counter substrate200are arranged, facing with each other, which have liquid crystal interposed therebetween. The upper polarizing plate510is applied onto the counter substrate200, and a lower polarizing plate520is applied to the lower surface of the TFT substrate100. A liquid crystal display panel3000is constituted by the TFT substrate100, the counter substrate200, the upper polarizing plate510, and the lower polarizing plate520. A backlight2000is disposed at the lower side of the lower polarizing plate520.

Referring toFIG. 14, use of the thin resin or thin glass for forming the TFT substrate100or the counter substrate200allows the liquid crystal display panel3000to have a flexibly bendable structure. The backlight2000including the light source, the light guide plate, the optical sheet, and the like is also configured to be flexible by using the thin resin for forming the light guide plate so that the overall liquid crystal display device becomes the flexible display device.

FIG. 15is a sectional view of the display region of the liquid crystal display device. AsFIG. 15shows, the liquid crystal display device is of IPS (In Plane Switching) type. The TFT for driving the liquid crystal is constituted by the oxide semiconductor. The present invention provides the barrier layer made of AlOx or the like for the purpose of protecting the oxide semiconductor from the externally penetrating moisture, or hydrogen generated in the material for forming the component.FIG. 15shows the TFT of top gate type.

Referring toFIG. 15, for example, the first barrier layer10which contains AlOx is formed on the polyimide TFT substrate100. The first barrier layer10is similarly structured to the one as described in the first embodiment referring toFIGS. 4 to 10. The structure is capable of protecting the TFT from externally penetrating moisture, or moisture, hydrogen, and the like generated in the polyimide substrate100.

The base film101made of SiOx or SiNx is formed on the first barrier layer10. Basically, the TFT formed on the base film101has the same structure as the one described in the first embodiment. Specifically, the semiconductor layer102constituted by the oxide semiconductor is formed on the base film101, and the gate insulating film103made of SiOx derived from TEOS covers the semiconductor layer102. The gate electrode104is formed on the gate insulating film103, and the interlayer insulating film105made of SiNx through the sputtering process is formed while covering the gate electrode.

A contact electrode1071is formed on the interlayer insulating film105. The contact electrode1071is connected to the drain electrode107of the TFT via the through hole, and connected to a pixel electrode122via the through hole. The drain electrode106as shown inFIG. 15is connected to the video signal line. Referring toFIG. 15, the inorganic passivation film40made of SiNx is formed on the interlayer insulating film105, for example, and the second barrier layer20which contains AlOx is formed on the inorganic passivation film. The second barrier layer20protects the TFT from moisture and hydrogen penetrating from above in cooperation with the inorganic passivation film40. Basically, the second barrier layer20also has the same structure as that of the first barrier layer10.

The organic passivation film108serving as a flattening film is formed on the second barrier layer20. A common electrode120is planarly formed on the organic passivation film108, and a capacitance insulating film121is formed on the common electrode. The pixel electrode122is formed on the capacitance insulating film. The pixel electrode122is connected to the contact electrode1071via the through hole. The capacitance insulating film121constitutes the storage capacitor together with the pixel electrode122and the common electrode120. Referring toFIG. 15, upon application of voltage to the pixel electrode122, the electric force line indicated by arrows is generated between the pixel electrode and the common electrode120for driving liquid crystal molecules251. An alignment film123is formed on the pixel electrode122for initial alignment of the liquid crystal molecules251.

AsFIG. 15shows, the counter substrate200is disposed opposite to the TFT substrate while interposing a liquid crystal layer250. The counter substrate200is also made of polyimide, and has the third barrier layer30made of AlOx at the inner side. The third barrier layer30serves to block moisture penetrating through the polyimide substrate200, or moisture, hydrogen, and the like generated in the polyimide substrate200. InFIG. 15, the third barrier layer30only includes the barrier layer. The barrier property may further be improved by forming the barrier layer simultaneously with formation of the inorganic insulating layer made of SiOx or SiNx according to the first embodiment as shown inFIGS. 9 and 10.

AsFIG. 15shows, a black matrix202and a color filter201are formed on the third barrier layer30, and an overcoat film203is formed while covering the color filter201. The alignment film123is formed while covering the overcoat film203for initial alignment of the liquid crystal molecules251.

The first barrier layer10, the second barrier layer20, and the third barrier layer30constitute the AlOx laminated structure as described in the first embodiment referring toFIG. 6. Therefore, this embodiment is capable of preventing moisture and hydrogen from influencing the liquid crystal layer or the oxide semiconductor, and suppressing warpage of the substrate.

In the case that the laminated structure of AlOx and Al is constituted by the first barrier layer10, the second barrier layer20, and the third barrier layer30as described in the second embodiment referring toFIG. 11, the backlight no longer transmits light in the presence of Al. Meanwhile, the liquid crystal display device of reflection type allows the first barrier layer10and the second barrier layer20to have the structure as described in the second embodiment referring toFIG. 11.

Fifth Embodiment

FIG. 16is a sectional view showing a fifth embodiment of the present invention. Referring to the sectional view of the display region of the liquid crystal display device as shown inFIG. 16, the TFT is of bottom gate type, which is different from the TFT as shown inFIG. 15. Referring toFIG. 16, likewise the structure as shown inFIG. 15, the first barrier layer10which contains AlOx is formed on the polyimide TFT substrate100, and the base film101is formed on the first barrier layer. The first barrier layer10also has the same structure as the one described in the first embodiment referring toFIGS. 4 to 10.

Referring toFIG. 16, the gate electrode104is formed on the base film101. The gate insulating film103is formed while covering the gate electrode104. The semiconductor layer102constituted by the oxide semiconductor is formed on the gate insulating film103corresponding to the gate electrode104. The drain electrode106and the source electrode107are formed on the semiconductor layer102, which are arranged opposite to each other. The inorganic passivation film40is formed while covering the semiconductor layer102, the drain electrode106, and the source electrode107, on which the second barrier layer20is formed.

The organic passivation film108is formed while covering the second barrier layer20. The layer configuration above the organic passivation film108is analogous to that of the liquid crystal display device as shown inFIG. 15, having the TFT of top gate type as described in the fourth embodiment. Specifically, the third barrier layer30made of AlOx is formed at the side of the counter substrate200as shown inFIG. 16for preventing penetration of moisture through the polyimide substrate200, or moisture and hydrogen generated therein into the liquid crystal layer250or the semiconductor layer102.

Basically, each structure of both the second barrier layer20and the third barrier layer30is the same as that of the barrier layer described in the first embodiment referring toFIGS. 4 to 10. Accordingly, this embodiment is capable of preventing moisture and hydrogen from influencing the liquid crystal layer250or the semiconductor layer102, and further suppressing warpage of the substrate. The first barrier layer10and the second barrier layer20of the liquid crystal display device of reflection type may have the same structure as the one shown inFIG. 11.

The present invention has been exemplified by the organic EL display device, and the liquid crystal display device as described in the embodiments referring to the sectional views. However, it is possible to implement the present invention to have different structures. For example, the organic EL display device as shown inFIG. 3is allowed to include other supporting film or the like between the polarizing plate500and the third barrier layer30, or to form the third barrier layer30on the upper electrode113, on which the protective layer114is further formed. With respect to the organic EL display device according to the first to the third embodiments, and the liquid crystal display device according to the fourth and the fifth embodiments, it is also possible to use any other resin or glass, in place of polyimide, for forming the TFT substrate100or the counter substrate200.