JPH03185425A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the elution of the various components included in glass substrates on the substrate surfaces of the liquid crystal display device which crimps a liquid crystal material between a pair of the transparent substrates by coating both the front and rear surfaces of the transparent substrates with hard carbon films. CONSTITUTION:The hard carbon films 2, 2' are provided on both the front and rear surfaces of the transparent substrates 1 and transparent electrodes for picture element electrodes are deposited by vapor deposition, etc., thereon and are patterned to prescribed patterns to form the picture element electrodes 4. Prescribed known stages are executed in succession thereto to obtain the liquid crystal display device. The hard carbon films 2, 2' are provided on both the surfaces of the substrates 1 in such a manner, by which the elution of the alkaline oxides, such as Na2O, K2O and BeO of the glass components of the transparent substrates 1 onto the surfaces of the substrates 1 and the consequent deterioration of the liquid crystal material are prevented. The display quality is, therefore, improved and the formation at a low temp. is attained. In addition, the yield is improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a liquid crystal display device, and more specifically, the present invention relates to a liquid crystal display device, in particular, a transparent substrate whose front and back surfaces are coated with hard carbon films, and a liquid crystal material is sandwiched between them. The present invention relates to a liquid crystal display device.

[Conventional technology]

Liquid crystal display devices include simple matrix type and active type.
There are two known matrix methods.

Currently, there is a shift towards the latter active matrix method. The reason for this is the demand for large-area LCD panels for OA.
It comes from the fact that it is emitted from devices such as LCD TVs. This active matrix method employs a method of providing an active element for each pixel. however,
In any case, both types of liquid crystal display devices have in common that they employ a structure in which a layer of liquid crystal material is sandwiched between a pair of transparent substrates.

Incidentally, in conventional liquid crystal display devices, glass is generally used as a transparent substrate. However,
When a glass plate is used as a transparent substrate, Na, OlK, OlBeOlMgOlZn are extracted from the glass.
There are disadvantages in that alkaline oxides such as OlFedMnO, Cab, and 5rO1BaO are eluted onto the substrate surface, deteriorating the liquid crystal material and causing deterioration of active element characteristics.

Taking these points into consideration, it has been proposed that (1) a glass substrate composed of components consisting of SiO, Am, 03, B20°, Na, and O be used as an electrode substrate for liquid crystals (particularly According to this publication (Japanese Patent Publication No. 60-6926).

Since the soda component in the substrate is sufficiently small, it is said that the elution of the soda component from the liquid crystal panel can be prevented, but it is actually difficult to completely prevent the elution of the soda component. (2) There is also known a liquid crystal display device that uses a plastic substrate as the transparent substrate on which no active elements are arranged to reduce its weight (Japanese Patent Application Laid-open No. 130717/1983,
However, with this structure, the transparent substrate on the side where the active element is placed is exposed to high temperature, and therefore the plastic substrate is used as the transparent substrate on the active element side. Furthermore, if a glass substrate is used, alkaline oxides will be leached onto the surface. Furthermore, (3) providing hard carbon as passivation for a glass substrate is described in Japanese Patent Laid-Open No. 64-921. By using this hard carbon for passivation of the glass substrate, the elution of alkaline oxides from the glass substrate surface to the liquid crystal layer is prevented, but heat treatment at about 300°C is required, and the transparent substrate is made of plastic. The use of substrates is inappropriate.

In addition to these, MIM elements are often used as one of the active elements. This is because it exhibits nonlinear current-voltage characteristics that are good for switching. Conventionally, MIM elements have been formed by providing a metal electrode such as Ta, ^α, Ti, etc. as a lower electrode on a transparent substrate such as a glass plate, and on top of this, an insulating film made of an oxide of the metal or 5iO1, 5iNz, etc. Aft is provided thereon as an upper electrode.
, Many have metal electrodes such as Cr.

However, MIM using metal oxide as an insulator (insulating film)
Element (Unexamined Japanese Patent Publication No. 57-196589, No. 61-2326)
No. 89, No. 62-62333, etc.), the insulating film is formed by anodic oxidation or thermal oxidation of the lower electrode, so the process is complicated and requires high-temperature heat treatment. However, high-temperature heat treatment is required to ensure removal of impurities, etc.), film controllability (uniformity and reproducibility of film quality and film thickness) is poor, and the substrate is limited to heat-resistant materials. Furthermore, since the M edge film is made of a metal oxide with constant physical properties, it is not possible to freely change the device material and device characteristics, and there is a drawback that the degree of freedom in design is narrow. This means that it is extremely difficult to design and manufacture a device that fully satisfies the specifications of a liquid crystal display device incorporating an MIM element. moreover,
As described later, the relative dielectric constant Er and the steepness β of the element are β
There is a relationship of oc 1/v'i'〒, and when Cr is high, the steepness decreases, making it unsuitable for high-density display1
It has the following drawbacks.

In addition, in the case of a HIM element using 5iO1 or 5iNz for the insulating film (Japanese Patent Laid-Open No. 61-275819), the insulating film is formed by a gas phase method such as plasma CVD or sputtering, but the substrate temperature is normal. Since a temperature of about 300° C. is required, a low-cost substrate cannot be used, and when the area is increased, the film thickness and film quality tend to become non-uniform due to the substrate temperature distribution. Furthermore, since these insulating films are synthesized in a gas phase, a large amount of dust is generated and the film has many pinholes, which reduces the yield of devices. Furthermore, the film stress is large and film peeling occurs, which also reduces the yield of the device.

On the other hand, as described above, a glass plate is usually used as the transparent substrate. This is because the formation of insulating films in conventional active elements requires heat treatment at 300 to 600°C.

[Problem to be solved by the invention]

The purpose of the present invention is to prevent the alkaline oxides contained in the glass substrate from leaching out from the substrate, thereby preventing the deterioration of the characteristics of the liquid crystal material and active elements, and in addition, preventing the occurrence of scratches due to work in each process. The present invention provides a liquid crystal display device that prevents the above problems from occurring, has good display quality, and has excellent long-term stability.

Another object of the present invention is that even when a plastic substrate is used as a transparent substrate, it is possible to prevent the diffusion of impurities and the generation of bubbles from the hygroscopic and breathable plastic substrate, and to prevent the substrate from warping. The present invention provides a liquid crystal display device that does not cause problems such as peeling.

Still another object of the present invention is to improve the functional strength of the MIM device when it is used as an active device, thereby improving long-term stability and yield. The present invention provides a liquid crystal display device capable of active matrix display.

[Means to solve the problem]

The present invention is a liquid crystal display device in which a liquid crystal material is sandwiched between a pair of transparent substrates, characterized in that both the front and back surfaces of the transparent substrates are coated with hard carbon films.

The inventors of the present invention have conducted many research studies on liquid crystal display devices, and found that by coating both the front and back surfaces of a transparent substrate with a hard carbon film, alkaline oxides from the glass substrate can be removed from the substrate surface. Elution is effectively prevented, diffusion of impurities and generation of bubbles from the surface of the plastic substrate are effectively prevented, and in addition, the substrate is not warped, and desirably, the insulating film of the Hijia element is If a similar hard carbon film is used, together with coating both surfaces of the transparent substrate with the hard carbon film, not only the range of choices for the transparent substrate will be further expanded, but also good device characteristics will be obtained. It has also been confirmed that the present invention has been made based on these.

The present invention will now be described in more detail with reference to the accompanying drawings.

As described above, the liquid crystal display device of the present invention is configured such that both the front and back surfaces of the transparent substrate are formed with a hard carbon film that can be formed at a deposition temperature of room temperature. The insulating film of the (HIM element) is also formed of a hard carbon film.

That is, in the present invention, the coating layer (insulating film) on both the front and back surfaces of the substrate is:
A hard carbon film containing at least one of amorphous and microcrystalline materials (i
-egg, diamond-like carbon film.

It consists of an amorphous diamond film (also called a diamond thin film).

One of the features of the hard carbon film is that it is a vapor-phase grown film.
As will be described later, the various physical properties can be controlled over a wide range by controlling the film forming conditions. Therefore, even though it is called an insulating film, its resistance value covers the range from semi-insulator to insulator, and in this sense, it is preferable to
The M element is an MSI element (Metal-5emi-I) described in Japanese Patent Application Laid-Open No. 61-275819.
SIS elements (an element consisting of a semiconductor-insulator-semiconductor, where the semiconductor is doped with impurities at a high concentration), etc.

The transparent substrate in the present invention can be made of many materials such as glass, polymeric materials (plastic plates, flexible polymeric films, etc.), and in particular, when polymeric materials are used, lower cost and thinner , a lightweight, impact-resistant liquid crystal panel can be obtained.

Examples of the glass substrate material include quartz, Pyrex, and soda lime glass, but the components in the glass are not particularly limited. Materials for polymer film substrates, plastic substrates, etc. include, but are not limited to, polyester (PUT), polyethersulfone (PES), polyethylene, polypropylene, polyamide, polycarbonate, and polyacetate.

As mentioned earlier, hard carbon films are provided on both the front and back surfaces of such a transparent substrate. The method for forming this hard carbon film and the physical properties of the film are common to those of the insulating film of the MIH element, so they will be described in detail later.

Next, manufacturing of the liquid crystal display device according to the present invention will be explained. First, the general thickness of the hard carbon film provided on both the front and back surfaces of the transparent substrate is 100-30.000λ, and is generally formed at a temperature of room temperature -950°C, preferably room temperature to 250°C. However, when using an MI element using a hard carbon film as an active element.

The temperature at which the hard carbon film is formed is not limited to this range.

A hard carbon film was formed on both the front and back sides of this transparent substrate, and ITOlZnO:
2. A transparent electrode material such as ZnO:SL, SnO,:Sb is deposited in several hundred layers by sputtering, vapor deposition, CVD, etc., and then patterned into a predetermined pattern. At this time, if the substrate is a simple matrix substrate, the transparent electrodes are patterned into stripes to obtain a liquid crystal display substrate. To make a substrate for an active matrix, as shown in Fig. 1, after patterning the transparent electrode, an active element (switching element) is attached to each pixel electrode 4.
5 and a common electrode 6 are provided. As the active element 5, a-3
Hard carbon film, SiNx, SiC, Ta, O, All
, O, etc. HIM element, XSI element, PIN
Diodes, back-to-back diodes, varistors, etc. are used. The common electrode wiring is made of the transparent electrode material used previously, Afi, Ni, Cr, Ni-Cr, No, T.
Using a highly conductive material such as a, Ti, Au, Ag, or Pt, several hundred to several layers are deposited by a method such as sputtering, vapor deposition, or CVD, and then patterned. In this way, an active matrix substrate is obtained.

A similarly prepared transparent substrate 1 with a hard carbon film 2 formed on the surface is used as the opposite substrate of these substrates, and an alignment material 8 such as polyimide is applied to the surface, and a rubbing treatment is performed to apply a sealing material. the gap material 9 is inserted to make the gap constant, and the liquid crystal 3 is sealed to form a liquid crystal display device (second
The liquid crystal display device obtained in this way can prevent contamination of the liquid crystal layer and the active layer of active elements from the transparent substrate with impurities, and can prevent deterioration of the liquid crystal layer and active elements. In order to increase the long-term stability of liquid crystal display devices,
Furthermore, when the transparent substrate 1 is a polymer film, it has hygroscopic and breathable properties, which causes bubbles to occur in the liquid crystal layer.
By coating both sides with the hard carbon films 2, 2, this can be prevented and the effect is great.In addition, if the hard carbon film is coated on only one side of the transparent substrate, the film stress and coefficient of thermal expansion will be reduced. Depending on the difference, curling of the substrate may occur during WA peeling, but by coating both sides of the substrate with a hard carbon film, it becomes possible to manufacture a liquid crystal device with high precision without deforming the substrate.

In addition, since both the front and back sides of the transparent substrate are coated with hard carbon films 2, 2, it is difficult to scratch, and it is possible to prevent scratches that occur during each process and rubbing, making it possible to manufacture a liquid crystal display device with good display quality. . Particularly for plastic substrates whose surfaces tend to be easily scratched, the effect of preventing scratches on one surface is very effective.

Yet again. A liquid crystal display device with good display quality can be manufactured by forming an MIM element using a hard carbon film as an insulating layer on a transparent substrate whose front and back surfaces are coated with hard carbon films. The fabrication of the MIM device will be described below with reference to FIG.

What is the image electrode 4 in Figure 1? IIM! This shows how a child is connected to a cram school. First of all, this thing has 3 customers.

A transparent electrode material for a pixel electrode is deposited by vapor deposition, sputtering, etc. on a transparent substrate with hard carbon films on both sides (not shown).

The pixel electrode 4 is formed by patterning into a predetermined pattern, and then a conductor thin film for the lower electrode is formed by vapor deposition, sintering, etc., and then a predetermined pattern is formed by wet smearing and dry etching. The first conductor 7 is turned to become the lower electrode, and then the plasma CvD method is applied.
Ion beam method, etc. ↓ After coating the hard carbon film 2', it is patterned into a predetermined pattern by dry etching, wet etching, or a lift-off method using a resist to form an insulating film, and then vapor deposition, sputtering, etc. A conductor thin film for a pass line is coated and patterned into a predetermined number of turns to form a second conductor 6 that will become a pass line, and finally an unnecessary portion of the lower electrode 7 is removed.
The transparent electrode pattern is made into a pixel electrode 4. In this case, the configuration of the HIM element (active element) 5 is not limited to this, but may include a configuration in which a transparent electrode is provided on the top layer after the MIM element is created, or a configuration in which the transparent electrode also serves as an upper or lower electrode. Various modifications are possible, such as forming an MIM element on the side surface of the lower electrode.

Here, the thickness of the lower electrode, upper electrode and transparent electrode is usually
They range from several hundred to several thousand A, several hundred to several thousand people, and several hundred to several thousand people, respectively. The thickness of the hard carbon film 2' in the KIN element is 100 to 8,000, preferably 200-sooo.

More preferably, it is in the range of 300 to 4000A.

The use of HIM elements using hard carbon films not only improves display quality and enables production at low temperatures;
Since there is a similar hard carbon film on the substrate surface, the adhesion is improved compared to the conventional hard carbon film of the insulating layer that was directly attached to the transparent substrate, and it is more resistant to external loads such as the rubbing process. This increases the yield rate. Furthermore, in the case of plastic substrates, it has been extremely difficult to fabricate active matrix devices using active elements due to their heat resistance, but with hard carbon films, high-quality films can be fabricated at substrate temperatures around room temperature. It is possible to fabricate it even on a plastic substrate, and is a very effective means for improving image quality.

Next, the material of the HIM element used in the present invention will be explained.

Materials for the first conductor 7, which becomes the lower electrode, include ribs, Ta,
Various conductors are used, such as Cr, W, No, Pt, Ni, and transparent conductors.

The materials for the second conductor 6, which becomes the pass line, are ^Q, C
A wide variety of conductors are used, such as r, Ni, Mo, Pt, Ag, and transparent conductors, but! -■ Characteristic stability and f
Ni, Pt, and Ag are preferred because they have particularly excellent a-reliability.

In the HIM element using a hard carbon film as an insulating film, the symmetry does not change even if the type of electrode is changed, and it can be seen from the relationship of QnIccf that Poole-Frenkel type conduction is performed. Further, from this fact, it can be seen that in the case of this type of HIM element, the upper electrode and the lower electrode may be combined in any manner. However, the device characteristics (1-V characteristics) deteriorate and change depending on the adhesion between the hard carbon film and the electrode and the state of the interface. Considering these, it was found that Ni, Pt, and Ag are good.

The current-voltage characteristics of the MIM element according to the present invention are shown in FIG. 3, and are approximately expressed by the conduction equation shown below.

I = exp (βV1/2) ・(1) ■
= Current V: Applied voltage N: Conductivity coefficient β: Poole-Frenkel coefficient n: Carrier density μ: Carrier mobility q: Electron charge Φ Nidrap depth ρ: Specific resistance d
: Thickness of the hard carbon film: Boltzmann's constant T: Ambient temperature t8: Dielectric constant ε of the hard carbon film. : An organic compound gas, especially a hydrocarbon gas, is used to form a hard carbon film on both the front and back surfaces of a vacuum dielectric transparent substrate and in a HIM element. The phase state of these raw materials does not necessarily have to be a gas phase at normal temperature and pressure; they can be used in either a liquid or solid phase as long as they can be vaporized through melting, evaporation, sublimation, etc. by heating or reduced pressure. be.

Regarding hydrocarbon gas as a raw material gas, for example, C
I4. Contains at least all hydrocarbons such as paraffinic hydrocarbons such as CzHa and C3H1CJzo, acetylenic hydrocarbons such as C and H4, olefinic hydrocarbons, acetinic hydrocarbons, diolefinic hydrocarbons, and even aromatic hydrocarbons. Gas is available.

Furthermore, other than hydrocarbons, any compound containing at least a carbon element can be used, such as alcohols, ketones, ethers, esters, CO1CO2, etc.

As a method for forming a hard carbon film from a raw material gas in the present invention, there is a method in which active species for film formation are formed through a plasma state generated by a plasma method using direct current, low frequency, high frequency, microwave, etc. Preferably, a method utilizing magnetic field effect is more preferable since the deposition is performed under low pressure for the purpose of increasing the area, improving uniformity, and forming a film at a low temperature.
However, active species can also be formed by thermal decomposition at high temperatures.

In addition, a hard carbon film may be formed through an ionic state generated by an ionization vapor deposition method or an ion beam vapor deposition method, or a hard carbon film may be formed from neutral particles generated by a vacuum vapor deposition method, a sputtering method, etc. Alternatively, a combination of these may be used to form a film.

An example of the deposition conditions for the hard carbon film produced in this manner is approximately as follows in the case of plasma CVD method.

RF crab On 1~5017cm pressure crab
10-3w 1OTorr Deposition temperature: Deposition -950℃ (
Although such a wide range can be adopted, preferably room temperature to
The temperature is 300°C, more preferably room temperature to 150°C. ) Due to this plasma state, the raw material gas is decomposed into radicals and ions and reacts, thereby forming carbon atoms on the substrate.
A hard carbon film containing at least one of amorphous (non-crystalline) and microcrystalline (crystal size is several tens of λ to several μ-) is deposited.The various properties of the hard carbon film are shown below. Note) Measurement method: Specific resistance (ρ): Determined from I-■ characteristics using a coplanar cell.

Optical band gap (Egopt): Obtain the absorption coefficient (α) from the spectral characteristics, (ahy)1/2=B(hv-Egopt)
Determined from the relationship.

Amount of hydrogen in the film (CH): 290 from infrared absorption spectrum
Integrate the peak around 0()-1.

Multiply the absorption cross section by MA.

CM: A-fα(v)/v-dv S P'/S P'' ratio: Infrared absorption Calculated from area ratio.

Vickers hardness (H): Based on micro Vickers meter.

Refractive index (n): By ellipsometer.

Defect density: Based on ESR.

As a result of analysis of the hard carbon film thus formed by IR@harvest method and Raman spectroscopy, it was found that carbon atoms formed SP3 hybrid orbitals and SP2 hybrid orbitals as shown in Figures 4 and 5, respectively. It has become clear that there are interatomic bonds. The ratio of sp” bonds to SP2 bonds is
It can be roughly estimated by peak-separating the IR spectrum. In the IR spectrum, spectra of many modes overlap in the range 2800 to 3150>-'', but the attribution of the peak corresponding to each wavenumber is clear, and the peaks are separated by Gaussian distribution as shown in Figure 6. If you perform separation, calculate the area of each peak, and find the ratio, SP
3/SP" ratio can be known.

Further, according to X-ray and electron diffraction analysis, it has been found that it is in an amorphous state (a-C: H) or an amorphous state containing microcrystalline grains of several tens of λ to several μ-.

In the case of plasma CVD method, which is generally suitable for mass production,
The lower the RF output, the higher the resistivity and hardness of the film, and the lower the pressure, the longer the life of the active species. There is a tendency for the number to increase. Furthermore, since the plasma density decreases at low pressures, methods using magnetic field confinement effects are particularly effective in increasing resistivity.

Furthermore, this method has the characteristic that it can form a hard carbon film of good quality even under relatively low temperature conditions of about room temperature to 150° C., so it is optimal for lowering the temperature of the MIM element manufacturing process. Therefore.

It has the advantage of increasing flexibility in selecting the substrate material to be used and making it easier to control the substrate temperature, allowing a uniform film to be obtained over a large area. Furthermore, as shown in Table 1, the structure, physical properties, etc. of the hard carbon film can be controlled over a wide range, so there is an advantage that device characteristics can be designed freely. Furthermore, the dielectric constant of the film is 2 to 6, which is Ta2O, which has been conventionally used in MIM.

Since it is smaller than AQzO, SiNx, when making an element with the same capacitance, the element size only needs to be larger, so microfabrication is not required and the yield is improved (from the relationship of H1 dynamic conditions, LCD The capacitance ratio between CLcD and HIM element is required to be approximately 10:1 (CLcD:CNIN=10:1).

Because it is! I If the permittivity is small, All! The Ii property increases, and the ratio between the on-current Ion and the off-current Ioff becomes large. Therefore, it is possible to operate the LCD at a lower duty ratio, and a high-density LCD can be realized. Furthermore, since the hard carbon film has high hardness, there is little damage caused by the rubbing process during encapsulation of the liquid crystal material, which also improves yield.

In view of the above points, by using a hard carbon film, a low-cost, gradation (color), and high-density LCD can be realized.

Furthermore, in addition to carbon atoms and hydrogen atoms, this hard carbon film contains
It may contain as a constituent element an element of group Ⅰ, an element of group ②, an element of group V of the periodic table, an alkali metal element, an alkaline earth metal element, a nitrogen atom, an oxygen element, a chalcogen element, or a halogen atom.

One of the constituent elements is the Group ■ element of the periodic table, which is also Group ■.
By introducing elements, alkali metal elements, alkaline earth metal elements, nitrogen atoms, or oxygen atoms, the thickness of the hard carbon film can be made approximately 2-3 times thicker than that of non-doped ones. In addition to preventing the occurrence of pinholes during device fabrication.

The mechanical strength of the element can be dramatically improved. Further, in the case of a nitrogen atom or an oxygen atom, the same effect as in the case of an element of group Ⅰ of the periodic table as described below can be obtained.

Similarly, devices that incorporate elements from group Ⅰ of the periodic table, chalcogen elements, or halogen elements dramatically improve the stability of the hard carbon film and also improve the hardness of the film, resulting in highly reliable elements. can be made. These effects can be obtained because Group (I) elements and chalcogen elements reduce active double bonds present in the hard carbon film. In addition, in the case of halogen elements, ■) the decomposition of the source gas is promoted by an abstraction reaction with hydrogen to reduce dangling bonds in the film, and 2) the halogen element
extracts the hydrogen in the C-H bond and replaces it, C-
This is because it enters the film as an X bond and increases the bond energy (the bond energy between C-8 and C-x is larger for C-x).

In order to use these elements as constituent elements of the film, raw material gases include, in addition to hydrocarbon gas and hydrogen, elements of group Ⅰ, group Ⅰ, and group ① of the Periodontal System Table.

Alkali metal elements, alkaline earth metal elements, nitrogen atoms,
A gas of a compound (or molecule) containing an oxygen atom, a chalcogen element, or a halogen element (hereinafter, these may be referred to as "other compounds") is used.

Examples of compounds containing Group I elements of the periodic table include B (OCz Is )3, B, H,, Rcl, B
Brl, B.F.

AQ (0-i-C, H7)a, (CH3)3AQ, (
CzHs)aAfl-(1-C4HJiAl-AQCQ
,,Ga(0-i-CJv)z-(CHz)3Ga,(
Cal(s)aGa, GaCQ, , GaBr3, (0-
There are i-C, H, ), In, (CJ, ), In, etc.

Examples of compounds containing Group Ⅰ elements of the periodic table include 5i
)1. , Si, H5i3H,, (C2)1. ), S
iH,SiF4,SiH,CQ,,5i(OCH□)I St (QC,H,)I St (QC3)1? )4,
GeCQl, GeH4, Ga(QC,H,), Ge
(C2H,), (CH,)4Sn, (C2Hs)4
There are Sn, 5nca4, etc.

Examples of compounds containing Group Ⅰ elements of the periodic table are:
PH,,PF,,PFPCQ,F,,PCQ,F,
PC is also PBr, , PO(OCHa)a, P(CzHs
)a, PO(4,, AsH3, AsCQ,, AsBr,
, AsF,, ^sF,, AsCQ3, SbH,,S
bF,, 5bCQ3゜5b(oc, o,), etc.

As a compound containing an alkali metal atom, for example, Li0
-i-C,H,,Na0-i-C,H,,KO-i-C
, II, etc.

Examples of compounds containing alkaline earth metal atoms include C
a (oc, Hs)a -Kg C0Cx +l5
)s, (CJs)zMg, etc.

Examples of compounds containing nitrogen atoms include nitrogen gas, inorganic compounds such as ammonia, organic compounds having functional groups such as amino groups and cyano groups, and nitrogen-containing heterocycles.

Examples of compounds containing oxygen atoms include oxygen gas, ozone, water (steam), hydrogen peroxide, -carbon oxide, carbon dioxide, carbon suboxide, -nitrogen oxide, nitrogen dioxide, dinitrogen trioxide, and dinitrogen pentoxide. , inorganic compounds such as nitrogen trioxide, hydroxyl groups, aldehyde groups, acyl groups, ketone groups, nitro groups, nitroso groups, sulfone groups, ether bonds, ester bonds, peptide bonds, and functional groups or bonds such as heterocycles containing oxygen. Further, examples thereof include organic compounds having a metal alkoxide, metal alkoxides, and the like.

Compounds containing chalcogen elements include, for example, H, S
,(co,)(cut)ms(cl,cui,CH,=
C1 (CIl, SCH□C)1=cH,, CJsSC
Js, CJsSCH:+, Thiophene, H, Se,
(CJs) zse, H, Te, etc.

Compounds containing halogen elements include, for example, fluorine,
Inorganic compounds such as chlorine, bromine, iodine, hydrogen fluoride, chlorine fluoride, bromine fluoride, iodine fluoride, hydrogen chloride, bromine chloride, iodine chloride, hydrogen bromide, iodine bromide, hydrogen iodide, alkyl halides Organic compounds such as halogenated aryl, halogenated styrene, halogenated polymethylene, and haloform are used.

In fact, in order to make, for example, an active matrix type liquid crystal display device of the present invention, hard carbon films 2, 2 are first deposited on both the front and back surfaces of a transparent substrate l, and a transparent film for a common electrode is formed on one surface of this film. Conductor such as ITO, ZnO:A
Q, ZnO: Si, SnO, In, Oa, etc. are deposited to a thickness of several micrometers from several hundreds by a method such as sputtering or vapor deposition, and patterned into stripes to form the common electrode 4.

An alignment material 8 such as polyimide is applied to each surface of the transparent substrate l on which the common electrode 4 is provided and the transparent substrate on which HIM elements are previously provided in a matrix (hard carbon films are formed on both the front and back surfaces). A sealing material is attached, a gap material 9 is inserted to make the gap constant, and a liquid crystal 3 is sealed to form a liquid crystal display device (FIG. 1).

〔Example〕

Examples will be shown next, but the present invention is not limited thereto.

Example I: Approximately 2 hard carbon films were formed on both sides of the PET substrate by plasma CVD method.
It was deposited to a thickness of 0.00 OA.

At this time, the film forming conditions were: Pressure: 0.05 Torr CH4 flow rate: 55CCM RF power: 11t/d Temperature: room temperature And so.

Next, by electron beam ([!,B,) deposition method.

After depositing ITO to a thickness of about 100 OA, it was patterned into stripes to form a common pixel electrode. Subsequently, a polyimide film was formed on this as an alignment film, and a rubbing treatment was performed.

A liquid crystal display device was fabricated by placing these substrates facing each other with each pixel electrode facing inward, pasting them together via a gap material with a diameter of about 5 μm, and then filling the thus formed cells with a commercially available liquid crystal material. .

Example 2 A PES substrate was used as a transparent substrate, and a hard carbon film was deposited on both sides of this substrate to a thickness of approximately 100 OA by plasma CVD.
Next, about 800 ITO was deposited using the magnetron sputtering method and then patterned to form a pixel electrode.

Next, an elbow M element using a hard carbon film as an active element was provided as follows.

First, about 100% of Al is deposited on the pixel electrode of the substrate by vapor deposition.
After depositing to an OA thickness, it was patterned to form a lower electrode.

A hard carbon film was deposited thereon as an insulating film to a thickness of approximately 900 mm by plasma CVD, and then patterned by dry etching.

Furthermore, approximately 10% of Ni is deposited on each hard carbon insulating layer by vapor deposition.
After depositing to a thickness of 0OA, it was patterned to form an upper electrode.

After depositing a hard carbon film to a thickness of approximately 100 OA on both sides of the PES substrate serving as the other transparent substrate (counter substrate), ITO was deposited to a thickness of approximately 100 OA by sputtering and patterned into stripes to form a common pixel electrode. . Furthermore, a color filter was placed on the opposite surface where the common pixel electrode was provided.

A polyimide film was formed as an alignment film on both substrates, and a rubbing process was performed.

Next, these substrates were placed facing each other with each pixel electrode facing inward, and then bonded together with a gap material in between, and a commercially available liquid crystal material was then filled into the thus formed cells to create a color liquid crystal display device. .

At this time, the hard carbon film formation conditions used for the NIN element were as follows: pressure: 0.035 TorrCH, flow rate:
10 SCCM RF power: 0.2 V/esi Temperature: Room temperature.

In addition, the conditions for forming the hard carbon film deposited on the substrate were as follows: pressure: 0.07 Torr CH, flow rate: 5 SCCM RF power: 0.5 V/cd, temperature = 100°C. Example 3 A Pyrex substrate was used as the transparent substrate, and a hard carbon film was deposited on both sides of the substrate to a thickness of about 3000 mm by plasma CVD.ITO was then vapor-deposited to a thickness of about 1000 mm as the primary pixel electrode. A2 was deposited by evaporation method as a zero-order lower electrode, which was then turned.
After the film was deposited to a thickness of 0.00 mm, it was patterned.

Next, about 800 hard carbon films were deposited by plasma CVD, and then patterned by dry etching.

Furthermore, Ni&F! is used as the upper electrode! , B, about 1 by vapor deposition method
After depositing to a thickness of 500 mm, patterning was performed.

A hard carbon film was deposited on both sides of the Pyrex substrate as the other transparent substrate (counter substrate), and then ITO was deposited to a thickness of about 1000 mm by sputtering, and then patterned into stripes to form a common pixel electrode. .

A polyimide film was formed as an alignment film on both substrates, and a rubbing process was performed.

Next, these substrates are placed facing each other with each pixel electrode side facing inside, and are pasted together with a gap material interposed between them.Furthermore, a commercially available liquid crystal material is sealed in the thus formed cell, as shown in Fig. 1. created a liquid crystal display device.

At this time, the conditions for forming the hard carbon film used in the HIM element are as follows.

Pressure: O, Q2 Torr CH4 flow rate: 205CCM RF power: 0.811/d Temperature = 100℃ Met.

In addition, the conditions for forming the hard carbon deposited on the substrate are as follows: pressure force CH9 flow rate RF power Temperature Met.

Example 4: 0. I Torr: 25 SCCM: I V/d: 150°C A MIM element was provided on a Pyrex glass substrate as one transparent substrate in the following manner. First, a hard carbon film was deposited on both sides of a Pyrex substrate to a thickness of about 1000 mm by plasma CVD.

Next, Cr was deposited to a thickness of about 1,000 ml by sputtering, and then patterned to form a lower common electrode. On top of that, approximately 1
After forming a 5iNxll film with a thickness of 0.00 mm, it was patterned to form an insulating film. Further, Cr was deposited on top of it to a thickness of about 2,000 ml, and then patterned to form an upper electrode. Approximately 10% of ITO was applied on the thus formed MIM element by sputtering.
After being deposited to a thickness of 0, it was patterned to form a pixel electrode.

A Pyrex substrate was used as a counter substrate, and a hard carbon film was deposited on both sides of the substrate to a thickness of about 1000 μm.

Next, ITO was deposited to a thickness of about 100 mm by sputtering, and then patterned into stripes to form a common pixel electrode.

Furthermore, these two substrates were bonded together via a gap material in the same manner as in Example 1, and then a commercially available liquid crystal material was encapsulated to produce a liquid crystal display device.

Example 5 A PET substrate was used as the transparent substrate. A hard carbon film was deposited on both sides of the substrate to a thickness of approximately 1,500 mm by plasma CVD. Next, a hard carbon film was deposited to a thickness of approximately 1,000 mm by ITIE, B, and evaporation. Next, a HIM element using a hard carbon film as an active element was provided in the following manner after patterning to form a pixel electrode.

First, An was deposited to a thickness of about 100 nm on the pixel electrode of the substrate by vapor deposition, and then patterned to form a lower electrode. A hard carbon film was deposited thereon as an insulating layer to a thickness of about 1200 mm by plasma CVD, and then patterned by dry etching. Further, as an upper electrode, Ni was deposited to a thickness of about 1,500 ml by a vapor deposition method, and then patterned.

The other transparent substrate is made of NET, and after depositing a hard carbon film on both sides of the substrate to a thickness of approximately 200 ml, ITO is applied to f! , B was deposited to a thickness of about 1,000 μm by vapor deposition and patterned into stripes to form a common pixel electrode.

A polyimide film is formed as an alignment film on both substrates.

A rubbing process was performed.

Next, these substrates were placed facing each other with each pixel electrode facing inward, and bonded together with a gap material interposed therebetween, and a commercially available liquid crystal material was then filled in the cells thus formed to produce a liquid crystal display device.

At this time, the conditions for forming the hard carbon film used in the MIM element were: pressure: 0.035 TorrCH, flow rate:
5 SCCM RF power: 0.15 V/aJ Temperature: room temperature.Furthermore, the film forming conditions for the hard carbon deposited on the substrate were: pressure C1, flow rate RF power temperature.

〔Effect of the invention〕

: 0. I Torr: 8 SCCM: 0.3 1/csf: 80°C The liquid crystal display device according to the present invention provides the following effects.

1) Na and O contained in the glass substrate are removed by coating hard carbon films on both the front and back surfaces of the transparent substrate.

K, O, BaO, MgO, ZnO, FeO, MnO,
It is possible to prevent alkaline oxides such as CaO, SrO, and BaO from being eluted onto the substrate surface, deteriorating the liquid crystal material, and deteriorating the device characteristics of the active device. Furthermore, since a hard carbon film is coated on both the front and back surfaces of the transparent substrate, scratches caused by operations in each process can be prevented, and a liquid crystal display device with good display quality and long-term stability can be produced.

2) By coating both sides of the plastic substrate with hard carbon, it is possible to prevent the diffusion of impurities from the substrate and the generation of air bubbles, even on plastic substrates with hygroscopicity and air permeability, and the hard carbon film is coated on both sides of the substrate. This prevents the board from warping and peeling.

3) Coating a hard carbon film on the substrate surface and HIN
If a hard carbon film is used for the insulating layer of the device, the mechanical strength of the device will be improved, and long-term stability and yield will be improved.

Furthermore, when the substrate is made of plastic, it has been difficult to fabricate active elements due to the high substrate temperature, but by using HIM elements using hard carbon films, active matrix display is possible even on plastic substrates, and the display quality is improved. It becomes possible to fabricate a high-density liquid crystal display device.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a state in which the HIM element and the image electrode are continuous. FIG. 2 is a partially cutaway perspective view of the liquid crystal display device. FIG. 3 is a current-voltage characteristic diagram of the HIM element in the present invention. FIG. 4, FIG. 5, and FIG. 6Wi are diagrams for explaining the properties of the hard carbon film in the present invention. l...Transparent substrate 2.2'...Hard carbon film 3...
・Liquid crystal 4...Pixel electrode 5...Active element
6... Common electrode (pass line) 7... Lower electrode (base electrode) 8... Alignment film 9... Gap material

Claims (1)

[Claims] (1) A liquid crystal display device in which a liquid crystal material is sandwiched between a pair of transparent substrates, wherein both the front and back surfaces of the transparent substrates are coated with hard carbon films.