JPH03203245A - Thin film transistor array - Google Patents

Abstract

PURPOSE:To make it possible to obtain a liquid crystal display panel which has a recessed display surface and reduces reflected light toward the user by using a specific board and combining liquid crystal with a transparent conductive film on the rear side. CONSTITUTION:At least a thin film 3 is formed on one side of a transparent polymer film-made substrate 2 selected out of SiOx (x: 1 to 2), ZrO2, Al2O3, SiC, TiC, SiN and TiN. A thin film transistor array 1 which comprises a gate electrode 4, a gate insulation film 5, a semiconductor layer 6 and source drain electrodes 7 and 8, is formed on the side where the thin film 3 is formed or on the side opposite to the thin film 3. This construction makes it possible to manufacture a liquid crystal display panel whose display surface is properly curved and hence to reduce reflected light.

Description

Detailed Description of the Invention (a) Industrial Application Field The present invention uses a visible transparent polymer film for the substrate, which allows for curved surfaces and large areas, and enables lightweight, thin and continuous production. The present invention relates to a thin film transistor array used as a switching element in a liquid crystal display panel.

(b) Conventional technology In recent years, a large number of gate lines (scanning lines) and drain lines (signal lines) are arranged perpendicularly to each other in an insulated state on a transparent substrate, which is one substrate of a liquid crystal display panel. Thin film transistor (hereinafter abbreviated as TPT) at the intersection
This is a so-called active matrix system in which images are displayed on televisions, etc. by providing a switching element as a switching element and driving it to open and close to give a signal to the display electrodes placed at each intersection, driving the display of the liquid crystal in this area. Liquid crystal display panels are being developed.

For example, there are TFT arrays for driving liquid crystal displays that use a quartz glass plate as a transparent substrate and a TPT of polycrystalline silicon formed thereon, and TFT arrays that use a glass plate as a substrate and form a TPT of a2-mol 77 silicon. It has been put into practical use.

Liquid crystal display panels using these TFT arrays have many advantages over cathode ray tubes in terms of driving voltage, power consumption, weight, and miniaturization, and are expected to have a wide range of applications.

(c) Problems to be Solved by the Invention However, TFT arrays using these quartz glass plates or glass plates as substrates have various drawbacks.

In other words, quartz glass is advantageous in that it has excellent heat resistance and is less likely to cause contamination problems, but on the other hand, it is difficult to manufacture large-area displays and to 7-otolithography due to multiple-sided mounting on a single substrate. Increasing the area of the substrate, which is essential for cost reduction through rationalization, poses the serious problem of high costs.

In addition, glass substrates do not have any cost problems when increasing in area, but they have a common drawback with quartz glass: their surfaces are generally flat, so the display surface of liquid crystal display panels that use these TFT arrays is It also has the problem that it is difficult to curve the surface.

The shape of the display surface has been studied from the viewpoint of improving visibility by reducing glare caused by reflection of external light.

As the display surface changes from a convex shape (such as the display surface of a cathode ray tube) to a flat shape (such as the display surface of a glass substrate display panel), and then to a concave shape, the external light intake angle decreases, and the amount of reflected light that enters the eye decreases. do.

Of course, it is technically possible to curve a glass plate or the like, but the cost is higher than that of a flat plate, and extremely advanced technology is required in the photolithography process.

As display devices become more widespread in general business, further improvement is desired from the viewpoint of fatigue prevention, and improvements are also required in the thin film transistor arrays that are their constituent parts.

On the other hand, general-purpose products that require simplicity, such as LCD pocket color televisions, make the most of the characteristics of LCD panels, and are lightweight and thin, as well as being suitable for continuous production using the roll-to-roll method. There is a particular need for cost reduction.

As a feature of roll-shaped continuous production, we have emphasized the cost advantage of the continuous process itself, but in addition to this, we must also describe the improvement in production yield by this method.

That is, the individual TPTs constituting the TFT array are extremely minute because they form individual pixels of the display panel, and the array is composed of a huge number of TPTs. Therefore, many defective products are generated due to dust. The advantage of continuous production in roll form is that since processing is performed continuously in a vacuum atmosphere, dust can be easily controlled and yields can be significantly improved.

By the way, in the production of TFT arrays, almost all manufacturing steps of gate electrodes, insulating films, amorphous silicon layers, source electrodes, drain electrodes, etc. are processed in a vacuum atmosphere.

However, if the substrate is a short substrate such as a glass plate, continuous processing in the above steps is extremely difficult.

As a result of intensive studies from the viewpoint of light transmission, the present inventors found that a transparent polymer film was used as a light-transmissive substrate, and at least one side of the polymer film was coated with SiOx (X is 1 to 2>, Z
rO2, Al2O,, T 8705, SiC.

A thin film of at least one of TiC5SiN or TiN is formed, and this thin film protects the substrate 12 in a high temperature environment during aging of a semiconductor layer such as amorphous silicon, and protects the substrate 12 when taken out to room temperature after depositing the semiconductor layer. We discovered that the curl of the substrate was small and the characteristics as TPT were fully comparable to TPT made of glass substrate.
This has led to the completion of the present invention. Transparent polymer films can produce flexible, thin, and lightweight thin film transistor arrays without the need for special film materials, as long as they have light transmittance and heat resistance that are better than windows. can.

Hereinafter, first, the thin film transistor array according to claim 1 will be explained in detail.

The thin film transistor array according to claim 1 of the present application includes a substrate made of a transparent polymer film, SiOx (x is 1 to 2) formed on one side of the substrate, ZrO2, A15-6-2O3, Ta70s, SiC, Tie. , a gate electrode, a gate insulating film, a semiconductor layer, and a source/drain formed on the formation surface of the thin film or on the side opposite to the formation surface of the thin film. It consists of electrodes.

The transparent polymer film substrate used in the present invention is not particularly limited as long as it has light transmittance and heat resistance equal to or higher than that of a window, and has visibility and electrical insulation properties. Typical examples include polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polysulfone, polyetherimide, 4-methylpentene terephthalate, polyphenylene sulfide, and transparent polyimide.

In the present invention, SiOx (x is 1 to 2), ZrO2, A1
2os, Ta2O3, SiC, TiC5SiN or Ti
A thin film of at least one type of N is formed.

As a method for forming these thin films, a sputtering method, an electron beam evaporation method, a plasma CVD method, etc. are appropriately used.

For example, to form SiOxillll by sputtering, SiOx is used as a cathode, the temperature of the transparent polymer film substrate is around 100℃, and the pressure is 2×10.
Torr, shatter voltage 2KV, frequency 13゜56MH
A method using a high frequency of z is adopted.

The thickness of this thin film such as SiO is 20 to 300 nm.
m, preferably in the range of 30 to 2O0nn,
If the film thickness is less than 20 m, the effect of protecting the transparent polymer film substrate in the high temperature environment during deposition of a semiconductor layer such as amorphous silicon and preventing curling will be reduced, while if it exceeds 300 nm, the SiOxll This is not preferable because the transparency of the film, etc. to visible light, etc. becomes poor, and the thin film is likely to peel off from the substrate.

In the present invention, in the substrate made of the transparent polymer film, a gate electrode, a gate insulating film semiconductor layer, and a source layer are formed on the surface on which the thin film is formed, or on the side opposite to the surface on which the thin film is formed.
A thin film transistor array consisting of drain electrodes is formed.

7- This thin film transistor array can have various structures such as staggered or coplanar.
Further, the method for forming it is not particularly limited, and may be a known method.

By the way, in the production of the Z thin film transistor array according to the present invention, when the above thin film is coated on one side of the substrate made of a transparent polymer film, surprisingly, when the thin film is formed on the side on which the thin film is formed, Or, regardless of whether it is on the side opposite to the side on which the thin film is formed, the substrate can withstand temperatures of about 200°C necessary for forming a semiconductor layer such as amorphous silicon, and curling is substantially prevented. , TPT with excellent properties can be obtained, and flexibility is maintained.

Next, the thin film transistor array according to claim 2 of the present application will be explained.

That is, in the thin film transistor array according to claim 2 of the present application, a substrate made of a transparent polymer film, SiOx (x is 1 to 2), ZrO2, A12O.
, Ta2C), SiC, TiC, SiN, or TiN, a gate electrode, a gate insulating film, a semiconductor layer, and a source/drain formed on one side of the 11 films. It consists of electrodes.

In the thin film transistor array of claim 2 of the present application, whereas the thin film transistor array of claim 1 of the present application has a thin film of SiOx (x is 1 to 2) formed on one side of a substrate made of a transparent polymer film, SiOx (
The major feature of x is that it forms a thin film such as 1 to 2), and the other points are the same as those in claim 1 of the present application, so a description thereof will be omitted.

In this way, SiO
When a thin film such as Moreover, a thin thin film transistor 7 layer with excellent characteristics can be obtained.

By the way, in manufacturing the thin film transistor array of the present invention, it is possible to flatten the surface and perform various treatments in the steps of forming each thin film layer and the 7th lithography 10-fi, etc., in the same manner as when handling a glass substrate. Further, by providing curvature when assembling the liquid crystal display panel, the display surface can be appropriately curved (hinged-back shape), so it is possible to reduce the above-mentioned reflected light to the operator.

Further, as a production method for the thin film transistor array of the present invention, so-called roll-to-roll continuous production can be adopted, so that costs can be reduced. Furthermore, the production yield is significantly improved due to the ease of dust control due to continuous roll production.

(e) TF with TPT provided on a flat, short substrate such as a working glass plate
When the T-array is used to manufacture a liquid crystal display panel, the display surface becomes flat, and there is a limit to the reduction in reflected light due to the reduction of the external light intake angle.

Furthermore, in the production of amorphous silicon layers and thin films for forming each electrode, processing is carried out in a vacuum atmosphere, but because of the short length, continuous production, which is advantageous for reducing costs, is difficult. must be taken out into the atmosphere, and during this time dust can cause a decrease in yield.

In the case of a TFT array in which one or both sides of a transparent polymer film substrate according to the present invention is coated with a specific thin film, it can be combined with a transparent conductive film as a transparent conductive substrate used on the opposite side via a layer of liquid crystal. This makes it possible to manufacture liquid crystal display panels with appropriately curved display surfaces.
It has the ability to significantly reduce reflected light.

In addition, in almost all production processes, the transparent polymer film substrate has the advantage of being rolled into a roll and processed continuously, so it can be used for amorphous silicon thin films, thin films for forming various electrodes, and thin films for forming various electrodes, which require particularly high productivity. In the process of depositing an insulating film in a vacuum atmosphere, the substrate is held in a roll in the same chamber and a thin film is continuously formed.1. In addition, it has the effect of almost solving the problem of dust, which causes a critical decrease in yield.

Furthermore, like the conventional TFT array using a glass plate or the like as a substrate, it can be used for full-color display by combining with an appropriate color filter.

(f) Examples Hereinafter, the present invention will be explained in detail based on Examples, but the present invention is not limited thereto.

1(a) to 1(c), FIG. 2, furthermore, FIG. 3, and FIG. 4 respectively show enlarged cross-sectional views of main parts of different thin film transistor arrays of the present invention. Figure 1 (
c) shows the structure of a star type thin film transistor array;
FIG. 2 shows the structure of another staggered thin film transistor array, and FIGS. 3 and 4 show the structure of a cobrana thin film transistor array.

In FIG. 1(a), (1) is a staggered thin film transistor array, and the staggered thin film transistor array (1) is formed as follows.

That is, a transparent polymer film substrate (2) is coated with a specific thin film (3) by vapor deposition, sputtering, etc. (1).
After forming a transparent conductive layer such as an ITO film (indium oxide tin oxide film) or a conductive metal layer such as chromium, molybdenum, aluminum, nickel, etc., patterning is performed by 7 otolithography to form a gate electrode (4). . next,
A gate insulating film (5) is formed on this gate electrode (4).The material of this gate insulating film (5) is an insulating material such as 5i0x (x is 1 to 2) for forming a thin film described above. ,
Can be used similarly.

The gate insulating film (5) is formed by appropriately selecting one of the methods described above, and is further patterned by 7-otolithography. Thereafter, an amorphous silicon-based semiconductor film is formed by a Blastoma CVD method or the like, and patterned by photolithography to form a semiconductor layer (6).

Next, to form a source electrode (7) and a drain electrode (8), an ITO layer, an aluminum layer, etc. are deposited by sputtering or vapor deposition, and patterned by 7 otolithography to form a source electrode (7) and a drain electrode. Electrode (8)
form. Further, a display electrode (not shown) 13-14- is formed in electrical contact with the source electrode (7), thereby completing the thin film transistor array. The display electrode is an ITO film deposited by vapor deposition or sputtering, and patterned by 7 otolithography.

Example 1 A polyethylene terephthalate film with a thickness of 75 μm was used as the substrate (2), and on one side thereof, a thin film (3
) was formed.

A thin film of AbOs is placed on one side of this substrate at a substrate temperature of 10°C.
A chromium film with a thickness of 2,000 yen was deposited by sputtering at 0'C, and then patterned by photolithography to form a gate electrode (4).

Next, a gate insulating film (5) made of silicon nitride (Si, Nt) having a thickness of 2,000 yen was formed over the entire surface by sputtering.

The sputtering conditions were as follows: substrate temperature was 100°C, Si3N was used as a cathode, and pressure was 5 x 10' Tor.
r, sputtering voltage 2KV, frequency 13.56 MHz
high frequency was used.

After that, a thickness of 2,
A semiconductor layer (6) consisting of 500% undoped amorphous silicon was deposited.

The conditions are that the substrate temperature is 180°C, silane diluted to 10 mol% is used as the raw material gas, and the flow rate is 2O08CC.
M, pressure 0.2 Torrx high frequency power density 0, 1
Watt/aLI2.

Next, an amorphous silicon pattern was formed in the transistor formation region by 7-otolithography.

Thereafter, an aluminum film with a thickness of 3,000 wafers was selectively deposited by sputtering to form a source electrode (7) and a drain electrode (8).

Furthermore, an ITO film with a thickness of 300 mm was deposited by sputtering, and display electrodes were formed by 700 mm thick.

The thin film transistor array thus obtained has a source-drain voltage Vsd of 10V1 and a gate voltage of OV~+
Drain current ratio (on/off ratio) is 4 digits in the 5V range,
It is 5 digits in the range of 0 to +10V, and is no inferior to that using a glass plate as a substrate.Moreover, it is flexible, and the characteristics change even when curved with a radius of 7. There wasn't.

Example 2 Polyethylene terephthalate with a thickness of 75 μm was used as a substrate, and a thin film of Ta2O5 with a thickness of 250 OA was formed on one side of the substrate by sputtering. The sputtering conditions were Ta=Os as the cathode, pressure 2X 10-3 Torr,
A voltage of 2 KV and a high frequency of 13.56 MHz were used, and the substrate temperature was 100°C.

Next, under the same conditions as in Example 1, a star-shaped TFT as shown in FIG.
I made an array.

The thus obtained TFT array was comparable to one using a glass plate as a substrate, was flexible and thin, and exhibited no change in characteristics even when curved to a radius of curvature of 71I1 m.

Example 3 A 100 .mu.m thick polyether sal 7on was used as a substrate, and a thin film of SiC of 1500 mm thick was formed on both sides of the substrate by a conventional method using silane and ethylene as raw material gases by plasma CVD.

The composition of SiC was 80 atm % Si.

Next, a star-shaped TFT array shown in FIG. 1(e) was manufactured in the same manner as in Example 1.

The thus obtained TFT array was comparable to one using a glass plate as a substrate, was flexible and thin, and showed no change in characteristics even when curved to a radius of curvature of 811-. .

A TFT array was manufactured using a polyethylene terephthalate film by performing the same process as in Example 1, except that the thin films of Comparative Examples AN and O were not formed.

The resulting array has a radius of curvature of 501 with the substrate side inside.
It is curled to Iln+, and the on-off ratio is such that the source-drain voltage Vsp is 10V1 and the gate voltage OV~+
The characteristics were not good as it was less than 3 digits in the range of 5V and less than 4 digits in the range from Ov to +1017 18-2.

(g) Effects of the Invention The TFT array of the present invention is formed by forming a light-transmitting and electrically insulating thin film on one or both sides of the substrate, and by using such a substrate, a flexible TFT array can be obtained. By combining the liquid crystal with a transparent conductive film on the back side, users can create a liquid crystal display panel with a concave display surface and reduced reflected light.

In addition, since the substrate is rolled into a roll and subjected to the manufacturing process continuously, continuous production is possible.
It is possible to significantly reduce production costs, and at the same time, each process can be performed continuously without taking it out from the vacuum atmosphere to the atmosphere, making it easy to manage 7 rays, greatly improving product yield, and providing high reliability. Therefore, an array with excellent characteristics can be obtained.

Further, since the TFT array of the present invention is lightweight and thin, it has the advantage that a TFT array for a liquid crystal display suitable for application to a portable device can be easily manufactured.

Furthermore, a laminated film consisting of a substrate, a transparent conductive layer, a liquid crystal layer, etc. that are pasted together can also be used over a moderately curved shaped panel made of acrylic resin, etc., and as a result, This method is extremely useful because it allows the production of curved liquid crystal display panels.

[Brief explanation of drawings]

pIS1 Figures (a) to 1(c), Figure 2, Figure 3, and Figure 4 respectively show enlarged sectional views of main parts of different vI membrane transistor arrays of the present invention, and Figures 1(a) to 1(c). FIG. 1(e) is an enlarged cross-sectional view of a main part of a staggered thin film transistor array, FIG. 2 is an enlarged cross-sectional view of a main part of another staggered thin film transistor array, and FIGS. 3 and 4 are different cobrana thin film transistors. An enlarged cross-sectional view of the main part of the array is shown. (1) Thin film transistor array, (2) Substrate, (3) Thin film, (4) Gate electrode, (5
)...Gate insulating film, (6>...Semiconductor scrap, (7)
...source electrode, (8)...drain electrode. 1... Thin film transistor array 2... Substrate 3... Thin film 4... Gate electrode 5... Gate insulating film 6... Semiconductor layer 259

Claims (2)

[Claims] (1) A transparent polymer film substrate, SiO_x (x is 1 to 2), ZrO_2, and Al formed on one side of the substrate.
_2, O_3, Ta_2O_5, SiC, TiC, Si
A thin film made of at least one of N or TiN, a gate electrode, a gate insulating film, a semiconductor layer, and a source/drain electrode formed on the side where the thin film is formed or on the side opposite to the side where the thin film is formed. Thin film transistor array. (2) A transparent polymer film substrate, SiO_x (x is 1 to 2), ZrO_2, and Al formed on both sides of the substrate.
_2O_3, Ta_2O_5, SiC, TiC, SiN
or a thin film transistor array consisting of a thin film made of at least one kind of TiN, a gate electrode, a gate insulating film, a semiconductor layer, and a source/drain electrode formed on one side of the thin film.