JPH02259729A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the performance of a liquid crystal substance caused by the elution of alkaline oxide contained in a substrate to the surface of the substrate by providing a hard carbon film layer on the surface of at least one substrate of a liquid crystal display device having a liquid crystal layer between a pair of transparent substrates. CONSTITUTION:A glass plate or a plastic plate, etc., is used as the insulating transparent substrate 1 of the liquid crystal display device and the hard carbon film 2 is provided on the substrate 1. After patterning is performed to the substrate 1, an active element 5 and a common electrode 6 are provided at every picture element electrode 4. An orientation material 8 made of polyimide is attached to the surface of the substrate 1 and a gap is made constant by a gap material 9, then the liquid crystal 3 is sealed. A metal-insulating material- metal (MIM) element is used as the active element 5 and the hard carbon film is used for the insulating material, so that the liquid crystal layer and the active layer of the active element are prevented from being contaminated by impurities from the substrate 1 and the liquid crystal display device with high display quality is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a liquid crystal display device used in displays of computer terminals, wall-mounted televisions, pocket televisions, and the like.

[Prior art]

A liquid crystal display (LCD) basically consists of two opposing glass substrates each with a plurality of display pixel electrodes, and the cells formed between these substrates filled with liquid crystal material. However, in the conventional method, Na, 0, O, Be contained in the glass substrate are displayed.
d, MgO, ZnO, Fed.

There is a problem in that alkaline oxides such as MnO, Cab, and 5rOtBaO are eluted onto the substrate surface, deteriorating the liquid crystal material and deteriorating the device characteristics of the active device.

In order to solve such problems, Japanese Patent Application Laid-Open No. 60-692
In No. 6, a glass component with a low soda content is used, but this does not completely prevent the problem.

Also, JP-A-60-130717 and JP-A-60-2
In No. 47685, a plastic substrate is used for the transparent substrate on which no active elements are placed in order to reduce the weight, but the substrate on which the active elements are placed has the disadvantage that a plastic substrate cannot be used because it requires high temperature treatment. .

Furthermore, in JP-A No. 64-92I, a hard carbon film is used as a passivation film for a glass substrate, but since the hard carbon film is heat-treated at about 300 degrees Celsius, it is difficult to form the film at room temperature. In addition, the plastic substrate had the drawback that it could not be used as a Bassibasimin film.

〔the purpose〕

SUMMARY OF THE INVENTION An object of the present invention is to overcome the conventional drawbacks by coating a transparent substrate with a hard carbon film at a low temperature, and to provide a liquid crystal display device with good display quality and long-term stability.

〔composition〕

As a result of intensive research to achieve the above object, we have developed a liquid crystal display device having a liquid crystal layer between a pair of transparent substrates, characterized in that a hard carbon film layer is provided on the surface of at least one of the substrates. It has been found that the above objects can be achieved by providing a device.

In a preferred embodiment of the invention, the liquid crystal layer has at least one metal-insulator-metal (MI
M) An element is provided, and the insulator is made of a hard carbon film.

That is, the feature of the present invention is that a hard carbon film is coated on a transparent substrate, and a pixel electrode is formed on the hard carbon film.

An active element is provided to form an active matrix substrate. More preferably, an MIM element is provided as an active element on this substrate, and a hard carbon film is used for this insulating layer.

In the present invention, a hard carbon film refers to a hard carbon film containing at least one of amorphous and microcrystalline materials (i-C film, diamond-like carbon film, amorphous diamond (also called diamond film).

Next, the manufacturing method and structure of the present invention will be specifically explained with reference to the accompanying drawings.

FIG. 1 is an explanatory diagram showing the form of a liquid crystal display device of the present invention.

First, a hard carbon film 2 is provided on the insulating transparent substrate 1, which may be a glass plate, a plastic plate, a flexible plastic film, or the like. The hard carbon membrane 2 has a thickness of 100 to 30,000, and is generally room temperature to 950°C, preferably room temperature to 25°C.
Formed at a temperature of 0°C. However, when using an MIM 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.

The method for manufacturing this hard carbon film 2 and the physical properties of the film will be described later. The substrates thus obtained are used to produce liquid crystal display substrates, optical sensor substrates, etc.

A substrate that has conventionally been used as a single transparent substrate is manufactured.

Here, ITO, Zno:A Q, ZnO:S are used as transparent electrode materials for liquid crystal display on a substrate provided with a hard carbon film, which will be explained below by taking a liquid crystal display substrate as an example.
A transparent electrode material such as SnO, :Sb is deposited in a thickness of several hundred to several micrometers by a method such as sputtering deposition or CVD, and then patterned into a predetermined pattern. At this time, if the substrate is for a simple matrix, the transparent electrodes are patterned into stripes to form a substrate for liquid crystal display. In order to use the substrate for an active matrix, after patterning the transparent electrode, an active element (switching element) 5 and a common electrode 6 are provided for each pixel electrode 4. The active element 5 is a TPT element using a-5L, Poly-3i, etc., and the insulating layer is a hard carbon film, SiNx, SiC, Ta,
O,,Afi,03. MIM element using etc., MSI
elements, PIN diodes, back-to-back diodes, varistors, etc. are used. The common electrode wiring is made of the previously used transparent electrode material, Aa, Ni, Cr, Ni-Cr.
, No, Ta, Ti, Au, Ag.

Sputtering deposition using highly conductive material such as PT.

A thickness of several hundred to several micrometers is deposited by a method such as the CVD method, and then buttered. In this way, an active matrix substrate was obtained.

A transparent substrate 1 made in the same manner was used as the opposite substrate to these substrates, an alignment material 8 such as polyimide was applied to the surface, a rubbing treatment was performed, a sealing material was applied, and a gap material 9 was put in to close the gap. A liquid crystal display device is obtained by keeping the temperature constant and enclosing liquid crystal 2. The liquid crystal display device obtained in this way can prevent contamination of the liquid crystal layer and the active layer of the active element from the transparent substrate with impurities, and can prevent deterioration of the liquid crystal layer and the active element. The long-term stability of the liquid crystal display device is increased, and since the surface of the transparent substrate is coated with a hard carbon film 2, it is less prone to scratches, which prevents scratches that occur during each process and rubbing. It becomes possible to manufacture. Particularly for plastic substrates whose surfaces tend to be easily scratched, the effect of preventing scratches on one surface is very effective.

Furthermore, by using an MIM element in which a hard carbon film is used as an insulating layer on a transparent substrate coated with a hard carbon film, a liquid crystal display device with good display quality can be manufactured. MIM below
The fabrication of the device will be described with reference to FIG.

First, on a transparent substrate coated with the hard carbon film obtained by the method described above, a transparent electrode material for an image electrode is deposited by a method such as vapor deposition sputtering, and patterned into a predetermined pattern.

Next, a metal thin film for the lower electrode is formed by a method such as vapor deposition or sputtering, patterned into a predetermined pattern by wet or dry etching to form the lower electrode 7, and then hardened by a plasma CVD method, an ion beam method, etc. After coating the 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 a thin metal film for the upper electrode is formed on it by a method such as vapor deposition or sputtering. The upper electrode 6 is formed by coating and patterning into a predetermined pattern, and finally the unnecessary portion of the lower electrode 7 is removed.
The transparent electrode pattern is exposed to serve as the pixel electrode 4.

In this case, the configuration of the MIM element is not limited to this, and after the MIM element is created, a transparent electrode is provided on the top layer, a transparent electrode also serves as an upper or lower electrode, and a side surface of the lower electrode. Various modifications are possible, such as one in which an MIM element is formed on the top.

The use of MIM elements using hard carbon films not only improves the display quality and enables manufacturing at low temperatures, but also allows the use of a similar hard carbon film on the surface of the substrate, making it possible to directly insulate the transparent substrate. Compared to a layer with a hard carbon film, the adhesion is improved, and the strength against external loads such as the rubbing process is increased, resulting in a 1-point improvement in yield. 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. However, a hard carbon film can be produced at a substrate temperature of about room temperature, and can also be produced on a plastic substrate, making it a very effective means for improving image quality.

Next, the material of the MIM element used in the present invention will be explained in more detail.

The material of the lower electrode 7 is A Q t D a, Cr
Various conductors are used, such as yW, No, Pt, Ni, and transparent conductors.

Next, the materials for the upper electrode 6 include AQ, Cr, N1 +
Various conductors such as transparent conductors can be used for MOr P i J Ag, but Ni, Pt, and Ag are preferable because they have particularly excellent stability and reliability of IV characteristics.

The symmetry of the MIM device using the hard carbon film 2' as the insulating film does not change even if the type of electrode is changed, and the Q n oe
From the relationship y' y, it can be seen that Poole-Frenkel type conduction is occurring. Further, from this fact, it can be seen that in the case of this type of MIM element, the upper electrode and the lower electrode may be combined in any manner. However, the device characteristics (IV characteristics) deteriorate and change depending on the adhesion between the hard carbon film and the electrode and the state of the interface. Considering these, Ni, Pt.

It turns out that Ag is good.

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

I=zaxp(βvL/2), (1) Engineering:
Current v: Cut m-ball χ: Conductivity coefficient β: Poole-Frenkel coefficient n: Carrier density μ: Carrier mobility
q: Electron charge Φ Nidrap depth ρ: Specific resistance d:
Hard carbon film thickness: Boltzmann constant T: Ambient temperature
ε, : Dielectric constant of hard carbon, : Vacuum permittivity The hard carbon film in the present invention will be explained in detail.

An organic compound gas, especially a hydrocarbon gas, is used to form a hard carbon film. 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, CH
4,C,H,,C3H,,C,H□. Paraffinic hydrocarbons such as C, 84, etc., olefinic hydrocarbons, acetylenic hydrocarbons.

Gases containing at least all hydrocarbons such as diolefinic hydrocarbons and even aromatic hydrocarbons can be used.

Furthermore, other than hydrocarbons, compounds containing at least the carbon element can be used, such as alcohols, ketones, ethers, esters, CO, and CO□.

The method of forming a hard carbon film from a raw material gas in the present invention is a method in which the film-forming active species is formed through a plasma state generated by a plasma method using direct current, low frequency, high frequency, microwave, etc. However, for the purpose of increasing the area, improving uniformity, and forming a film at a low temperature, a method using a magnetic field effect is more preferable because the deposition is performed under low pressure. Active species can also be formed by thermal decomposition at high temperatures. . Alternatively, it may be formed through an ion state generated by an ionization vapor deposition method, an ion beam vapor deposition method, or the like.

It may be formed from neutral particles produced by vacuum evaporation, sputtering, or the like.

Furthermore, it may be formed by a combination of these.

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

RF output: 0.1 to 50 V/a # Pressure: 101 to 1.0 Torr Deposition temperature: Room temperature to 950° C. Due to this plasma state, the raw material gas is decomposed into radicals and ions and reacts.

A hard carbon film containing at least one of an amorphous (non-crystalline) and a microcrystalline (crystal size: several tens to several microliters 11) consisting of carbon atoms C and hydrogen atoms H is deposited on the substrate. Further, various properties of the hard carbon film are shown in Table 1.

Table 1 Note) Measurement method: Specific resistance (ρ): Determined from the IV characteristics of a coplanar cell.

Optical band gap (Egopt): Obtain the absorption coefficient (α) from the spectral characteristics and determine from the relationship (ahv) = B (hv-Egopt).

Amount of hydrogen in the film (CM): 2900 from infrared absorption spectrum
It is determined by integrating the peak around m-' and multiplying by the absorption cross section A. Namely.

C□=A test fα(w)/w ratio S P'/S P'' ratio: Infrared absorption spectrum, sp
', sp'' are decomposed into Gaussian functions that belong to each, and the area ratio is obtained.

Vickers hardness (H) by 2 micro Vickers meter.

Refractive index (n): By ellipsometer.

Defect density: Based on ESR.

The hard carbon film thus formed was measured using Raman spectroscopy and IR spectroscopy.
As a result of analysis by the absorption method, it was revealed that there were interatomic bonds in which the carbon atoms formed the SF3 hybrid orbital and the SF3 hybrid orbital, as shown in Figures 4 and 5, respectively. There is. sp” bond and SP1 bond ratio is IR
It can be roughly estimated by separating the peaks of the spectrum. I
In the R spectrum, many mode spectra from 2800 to 3150 aa-1 are measured to overlap, but the attribution of the peak corresponding to each wave number has been clarified.
If you perform peak separation using Gaussian distribution as shown in Figure 6, calculate the area of each peak, and find the ratio, SP
You can know "/SP".

Also, according to x, m and electron diffraction analysis, amorphous 7I! (a-C: )l) and/or is in an amorphous state containing microcrystalline grains of about 50 to several μm in size.

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 to increase. Furthermore, since the plasma density changes at low pressure, the method using the magnetic field confinement effect is
It is particularly effective in increasing specific resistance.

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, the degree of freedom in selecting the substrate material to be used is increased, and the substrate temperature can be easily controlled, so that a uniform film can be obtained over a large area.

In addition, the structure and physical properties of the hard carbon film are as shown in Table 1.
Since it can be controlled over a wide range, there is also the advantage that device characteristics can be designed freely. Furthermore, the dielectric constant of the film is 3 to 5, which is conventionally used in MIM. Ta, O,, A Q
Since it is smaller than zoa and SiNx, when manufacturing an element with the same capacitance, the element size only needs to be larger, so microfabrication is not required so much, and the yield is improved.

(Due to the driving conditions, the capacitance ratio of the LCD and MIM element is C
-C=10:1 is required)LCD"MI River 17・Previous 1.1= *1°Element steepness β"F co, so if the dielectric constant ε is small, the steepness will be large, and the ON The ratio between the current Ion and the off-state current IOFF can be increased. Therefore, it is possible to drive the LCD at a lower duty ratio, and a high-density LCD can be realized. Furthermore, since the 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.

In addition to carbon atoms and hydrogen atoms, this hard carbon film
Group ■ elements of the periodic table, Group ■ elements of the periodic table.

Elements from group Ⅰ of the periodic table as one of the constituent elements, which may include group Ⅰ elements, alkali metal elements, alkaline earth metal elements, nitrogen atoms, oxygen elements, chalcogen elements, or halogen atoms as constituent elements; Similarly, when group Ⅰ elements, alkali metal elements, alkaline earth metal elements, nitrogen atoms, or oxygen atoms are introduced, the thickness of the hard carbon film can be made approximately 2 to 3 times thicker than that of non-doped ones. Moreover, this can prevent the occurrence of pinholes during device fabrication and dramatically improve the mechanical strength of the device. 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 in the case of group Ⅰ elements and chalcogen elements, active double bonds existing in the hard carbon film are reduced, and in the case of halogen elements, 1) abstraction for hydrogen is achieved. The reaction promotes the decomposition of the raw material gas and reduces dangling bonds in the film, and
extracts the hydrogen in the C-H bond and replaces it, C-X
It enters the membrane as a bond, increasing the bond energy (C
This is because the bond energy between -H and between C-X is larger for C-X.

In order to use these elements as constituent elements of the film, in addition to hydrocarbon gas and hydrogen, the material gases must include elements from group Ⅰ, Ⅰ, ①, In order to contain an alkali metal element, an alkaline earth metal element, a nitrogen atom, an oxygen atom, a chalcogen element or a halogen element,
Gases of compounds (or molecules) containing these elements or atoms (hereinafter, these may also be referred to as "other compounds J") are used.

Examples of compounds containing Group Ⅰ elements of the periodic table in 2N include B(OCis) i la, o, l BCna
t BBr) lBF3 t A Q (0-i-C3
Ht)x r (CH3))A Q + (CzHg)
j Q t(1-C41+*)3A Q t A Q
CQ 3 + Ga(0-1-CJt)ip (CH
s) aGa, (CtHs)xGa* GaCQ 2
, GaBra e (0-f-CiHt)tIn,
(C,Hl)3In and the like.

As a compound containing an element of group Ⅰ of the periodic table.

For example, Si, H, (C, Hs), SIH, SiF,
SiH, CJ2. , SiCQ 4t 5i (OC
Hj)4t5i(OCl)11)4t5i(o
ciot) * fGeCI241 GeH4v Ge(
QC,)11), Ge(CJs)ms (CHi)
, Sn, (C,)I, )4Snt 5nCfi4, etc.

As a compound containing an element of group Ⅰ of the periodic table, for example, P
H,, PF, , PF, , PCΩ, F,, PC
Q.F.

pcIl,, PBr,, PO(OCR,) at P
(C,H8)It POcns*AsHa, AsCQ
,, AsBr,, AsF,, AsF,, AsC
jl, tSbHa, 5bFa -SbCj! s t
There are Sb(OCJg)s, etc.

As a compound containing an alkali metal atom, for example, Li0
-1-C,H,,Na0-i-C,)It t KO-
i-C, )l, etc.

As a compound containing an alkaline earth metal atom.

For example, Ca(OCJi)a + Mg(OCxHi)3
+ (CJs)Jg, 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.

Examples of compounds containing chalcogen elements include H*S
-(CH3)(CH-)4S(C)Is)*CHs-
CHi =CHCHsSCH, CH=CH,,C,H,
SC,H,,C,HISCH,,thiophene, )I,
See CClHg')*Seg H, Ta, 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.

The present invention will be explained in more detail below with reference to the following examples, but the present invention is not limited thereto.

(Left below) Example 1 A hard carbon film was formed on a plastic substrate using the plasma CVD method.
000 people deposited.

At this time, the film forming conditions were: Pressure Crab 0.05 Torr CH4 style i: 5 SCCM RF power: IW/cd Temperature: room temperature And so.

Next, by electron beam (E, B,) evaporation method,
After depositing 1000 ITO layers, it was patterned into stripes to form a common pixel electrode.

Subsequently, a polyimide film was formed thereon as an alignment film, and a rubbing treatment was performed.

Next, these substrates were placed facing each other with each pixel electrode side facing inside, and were bonded together with a gap material having a diameter of 5 μm interposed therebetween, and a commercially available liquid crystal material was then sealed in the thus formed cells to create a liquid crystal display device. Ta.

Example 2 A plastic substrate was used as the transparent substrate. 1000 layers of hard carbon was deposited on this substrate by plasma CVD method. 800 layers of ITO was deposited using magnetron sputtering method. Then, it was patterned to form pixel electrodes. was formed.

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

First, AQ was deposited to a thickness of 1,000 layers 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 to a thickness of 900 mm as an insulating film by plasma CVD, and then patterned by dry etching.

Furthermore, 1000% Ni was deposited on each hard carbon insulating film by vapor deposition.
After depositing it to a thickness of 100 mL, it was patterned to form an upper electrode.

Next, a hard carbon film of 1,000 layers is deposited on a flexible plastic film substrate as the other transparent substrate (counter substrate), and then ITO is deposited to a thickness of 1,000 layers by sputtering and patterned into stripes to form a common pixel electrode. did. Furthermore, a color filter was provided on the opposite surface where the common pixel electrode was provided.

Next, 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 side facing inside, and were bonded together with a gap material interposed therebetween, and a commercially available liquid crystal material was further sealed in the thus formed cells to produce a color liquid crystal display device.

At this time, the hard carbon film formation conditions used for the MIM element were as follows: Pressure Crab 0.035 Torr CH4 flow rate: 10 SCCM RF power: 0.2W/cd Temperature: room temperature Met.

Also, what are the conditions for forming the hard carbon film deposited on the substrate?

Pressure Crab 0.07 min orr CH, flow rate: 5 SCCM RF power: 0.5W/aJ Temperature: 100℃ Met.

Example 3 A Pyrex substrate was used as a transparent substrate, and 3,000 hard carbon films were deposited on this substrate by plasma CVD.

Next, 1000 layers of ITO were deposited by vapor deposition as a pixel electrode, and then buttered. Next, 1500 layers of AQ were deposited by vapor deposition as a lower electrode, and then buttered.

Next, a hard carbon film of 800 mm was deposited by plasma CVD, and then patterned by dry etching. Furthermore, 1,500 pieces of Ni was deposited as an upper electrode by E, B, and evaporation methods, and then buttered.

Next, a hard carbon film of 3,000 layers was deposited on the Pyrex substrate as the other transparent substrate (counter substrate), and then ITO was deposited to a thickness of 1,000 layers by sputtering, and then patterned into stripes to form a common pixel electrode. did.

Next, 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 therebetween.A liquid crystal display device as shown in the figure is then created by filling the cells formed in this way with a commercially available liquid crystal material. made.

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

Pressure Crab 0.02 Torr CH4 flow rate: 20 SCCM RF power: 0.8W/cd Temperature: 100℃ Met.

Also, what are the conditions for forming the hard carbon film deposited on the substrate?

pressure crab 0. I Torr CH4 flow rate: 25 SCCM RF power: IW/ad Temperature: 150° C. Example 4 A MIM element was provided on a Pyrex glass substrate as one transparent substrate in the following manner. First, 1000 hard carbon films were deposited by plasma CVD.

Next, after depositing Cr to a thickness of 100 OA by sputtering, it was patterned to form a lower common electrode.
After forming a deposited iN film with a thickness of 0.000 nm, it was patterned to form an insulating film. Furthermore, after evaporating Cr to a thickness of 200 OA, it was patterned and used as an upper electrode.ITO was deposited on the MIM element thus formed to a thickness of 500 OA by sputtering.
After the film was deposited to a certain thickness, it was patterned to form a pixel electrode.

Next, a Pyrex substrate was used as a counter substrate, and a hard carbon film was deposited on this to a thickness of 100 OA.

Next, after depositing 500 layers of ITO using sputtering method,
A common pixel electrode was formed by patterning it into stripes.

Further, 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 sealed to produce a liquid crystal display device.

〔effect〕

(i) By coating a hard carbon film on a transparent substrate, Na, O, K, O, Be contained in the glass substrate can be
d, Mg0t ZnO, Fed, MnO, Cab,
SrO.

It is possible to prevent alkaline oxides such as BaO from eluting to the substrate surface and deteriorating the liquid crystal material or deteriorating the device characteristics of the active element. Similarly, in the case of a plastic substrate, it is possible to prevent the influence of adsorbed water from the substrate and to improve the chemical resistance of the substrate. Furthermore, since it is coated with a hard carbon film, it is possible to prevent scratches caused by work in each process and scratches that occur during rubbing processing, resulting in good display quality and long-term stability (
This makes it possible to provide a liquid crystal display device with excellent environmental resistance.

(ii) When the substrate surface is coated with a hard carbon film and the hard carbon film is used as the insulating layer of the MIM element,
The mechanical strength of the device is improved, and long-term stability and yield are improved.

Furthermore, when the substrate is plastic, it has been difficult to fabricate active elements due to the high substrate temperature, but by using MIM elements using hard carbon films that can be formed at low temperatures, active matrix display can be achieved even on plastic substrates. This makes it possible to manufacture high-density liquid crystal display devices with good display quality.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a liquid crystal display device of the present invention, and FIG. 2 is an explanatory diagram of an MIM element. FIG. 3 shows the current-voltage (I-V) characteristics of the MIM element. Figures 4, 5 and 6 show the characteristics of the hard carbon film. 1... Transparent substrate 2, 2'... Hard carbon film 3... Liquid crystal material 4... Pixel electrode 5...
Active element 6...Common electrode (upper electrode) 7...Lower electrode 8...Alignment film 9...Gap material patent applicant Rico Co., Ltd. - Figure 3 Figure 6 (1st letter) Crn - '

Claims (1)

[Scope of Claims] 1. A liquid crystal display device having a liquid crystal layer and an active element between a pair of transparent substrates, characterized in that a hard carbon film layer is provided on the surface of at least one of the substrates. 2. The liquid crystal display device according to claim 1, wherein the active element is a metal-insulator-metal (MIM) element, and the insulator is made of a hard carbon film.