JPH0618908A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To enable bright display to be effected by commonly using the pixel electrodes formed on one substrate as a light scattering layer. CONSTITUTION:Fine ruggedness is formed on the prescribed surface of the substrate 1 on the side where the pixel electrodes 3 are provided. The ruggedness is reflected to a passivation film 2 and pixel electrodes 3 provided thereon. Transparent electrodes 9 are formed in a stripe form on another substrate 10. A liquid crystal layer dispersed with liquid crystal phases 7 in a high polymer 6 is held between the substrates 1 and 10. The liquid crystal molecules in the liquid crystal phases 7 line up irregularly in the state of not impressing a voltage to the liquid crystal layers 6, 7. Light 1 entering from the substrate 10 is scattered and absorbed in the liquid crystal layer, by which a reflected light quantity 12 is drastically decreased. On the other hand, the liquid crystal molecules in the liquid crystal phases 7 are oriented in an electric field direction in the state of impressing the voltage to the liquid crystal layer and the incident light 11 transmits the liquid crystal phases 7 and is reflected by the pixel electrodes 3. The reflected light quantity 12 is thereby increased. The incident light 11 is reflected as scattered light by the ruggedness on the surface of the pixel electrodes 3.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art One of the display methods in a liquid crystal display device is
There is a so-called scattering type that utilizes the change in a state of transmitting light and a state of scattering light depending on whether a voltage is applied to the liquid crystal layer or not. This system does not require a polarizing plate as compared with a TN type or STN type which requires a polarizing plate. Therefore, without the loss of light due to the polarizing plate,
A bright display is possible, and a direct-viewing (reflection-type) liquid crystal display device that does not require illumination such as a backlight becomes possible. Further, in recent years, as one of scattering type liquid crystal display devices, a polymer dispersion type liquid crystal display device in which liquid crystal is dispersed in a polymer matrix has been proposed, but these are not easily affected by the thickness of the liquid crystal layer. It is attracting attention because of its features such as large area and no need for polarizing plate. In addition, IEICE Technical Report EID89-103,
By using a polymer network type liquid crystal in which liquid crystal is dispersed in a three-dimensional network structure formed by an ultraviolet polymerizable compound as a liquid crystal layer of a display element, advantages such as low voltage driving and excellent steepness can be obtained. There is. However, in these methods, the solvent and unreacted prepolymer used when forming a composite of liquid crystal and polymer, and impurities generated by decomposition of the liquid crystal or prepolymer by ultraviolet rays are surrounded by the liquid crystal layer. In particular, there is concern about reliability. Moreover, many polymer layers other than the liquid crystal are formed between the upper and lower electrodes, so that the voltage actually applied to the liquid crystal layer is lowered and the drive voltage tends to be increased. It was It has been shown that an electrode also serving as a light scattering layer is formed on a substrate having irregularities for the purpose of solving such a problem. However, in order to realize a high-definition, large-screen display, when an active matrix (switching element is added to each pixel) configuration is used, the switching element is formed on the unevenness,
There was a problem with the reliability of the device. Thin film transistors and MIMs are known as switching elements for driving liquid crystals, but MIMs having a hard carbon film as an insulating layer were preferable in terms of low-temperature process, high aperture ratio, low cost, and the like. Further, when the liquid crystal display is a transmissive type by backlight light, it is necessary to connect a transparent pixel electrode (ITO or the like) and MIM or to use one electrode of the MIM as a transparent electrode.
Fine patterning of the transparent electrode was unavoidable. However, in the fine patterning of the transparent electrode, problems such as ITO etching residue and etchant residue that adversely affect the reliability of the MIM element are likely to occur, and the ITO pattern forming process was desired to be deleted if possible. Further, in the transmissive liquid crystal display device, a transparent substrate has to be used, and the choice of the substrate is limited.

[0003]

An object of the present invention is to solve the above problems and to provide a liquid crystal display device having a high display quality by improving the above problems and realizing a bright display. It is what

[0004]

[Structure] The structure and operating mechanism of the liquid crystal display device of the present invention will be described with reference to FIG. 1, which schematically shows the basic structure of the liquid crystal display device of the present invention. The configuration of the liquid crystal display device will be described. Fine irregularities are formed on a predetermined surface of the substrate 1 on which the pixel electrodes 3 are provided (portions where the pixel electrodes 3 are provided), and the irregularities are reflected on the passivation film 2 and the pixel electrodes 3 provided thereon. To be done. A passivation film 2'is also formed on the opposite surface of the substrate. However, the passivation films 2 and 2 ′ are not necessarily provided if reliability is secured. The other substrate 10
The transparent electrodes 9 are formed in a stripe shape. The liquid crystal display device is manufactured by sandwiching a liquid crystal layer between the substrates 1 and 10. As the liquid crystal layer, a polymer 6 having liquid crystal 7 dispersed therein was used. Depending on the display mode, the liquid crystal phase 7 and the dye 8
In particular, a structure containing a dichroic dye can also be adopted. Light scattering on the surface of the pixel electrode is also caused by nonuniformity of the surface structure of the pixel electrode. Especially for Al sputtered film,
Specular reflectance is 90 to 0% depending on coexisting gas species and substrate temperature
Arbitrarily change between. In a general thin film device, an Al sputtered film having a smooth surface and a large specular reflectance is used as a wiring. Suitable manufacturing conditions for a thin film having a small specular reflectance are: pressure 1 × 10 ⁻³ to 1 × 10 ⁻¹ torr substrate temperature room temperature to 350 ° C. coexisting gases N ₂ , O ₂ , H ₂ , H ₂ O, hydrocarbons The deposition rate is 3000 Å / min or less. Above all, the effect of the coexisting gas is large, and N ₂ , O ₂ and hydrocarbon are effective in reducing the specular reflectance of the sputtered film. The decrease in the specular reflectance of the film surface is caused by the non-uniformity of the orientation surface of the film [(111), (20
0), (220), and (311) planes become clear, the specular reflectance decreases, and when the (111) planes are selectively formed, it becomes a mirror surface] and due to surface non-uniformity caused by hillocks. ing. As long as these non-uniform surfaces can be formed, the manufacturing method, manufacturing conditions, pixel electrode material, etc. are not limited.

A liquid crystal display mechanism of the liquid crystal device will be described. When no voltage is applied to the liquid crystal layers (6, 7, 8), the liquid crystal molecules in the liquid crystal phase 7 are irregularly arranged, and the light 11 incident from the substrate 10 is scattered in the liquid crystal layer and absorbed by the dye. , The amount of reflected light 12 is greatly reduced. On the other hand, when a voltage is applied to the liquid crystal layer, the liquid crystal molecules in the liquid crystal phase 7 are oriented in the direction of the electric field, the incident light 11 passes through the liquid crystal phase, is reflected by the pixel electrode 3, and the amount of reflected light is that no voltage is applied. It greatly increases from time to time. At this time, the incident light is reflected as scattered light by the unevenness of the surface of the pixel electrode.
In this way, the amount of reflected light varies depending on whether the voltage is applied or not applied, which enables display. Further, by forming various color filters on the substrate 10, it is possible to colorize the liquid crystal display.

The size of the fine concavo-convex pattern structure on the substrate is preferably about 1 to 5 μm in the substrate plane direction and about 1 μm or less in the substrate vertical direction. As a method for forming a fine concavo-convex pattern on a substrate, there is a method in which a polymer substrate containing fillers or inorganic fine particles or a polymer substrate having inorganic fine particles dispersed on the surface is subjected to plasma treatment with an inert gas such as Ar. To be When the polymer substrate containing the filler or the inorganic fine particles is subjected to the plasma treatment, the polymer portion is etched but the filler or the inorganic fine particle portion is not etched, so that irregularities corresponding to the size of the filler or the inorganic fine particles are formed. It In addition, a polymer substrate on which inorganic fine particles are dispersed may be used to form irregularities on the substrate. Also in this case, the portions without inorganic fine particles are selectively etched to form irregularities. In these etchings, when the etching rate is low, the surface of the inorganic fine particles or the filler is covered with the plasma polymerized film of the etched component. When the etching rate is high, the filler-containing polymer substrate is exposed with the filler to form irregularities. Furthermore, as another aspect, a method of forming a predetermined unevenness by etching a thin film having no unevenness formed on the substrate, a thermoplastic, thermosetting, or ultraviolet curable polymer or the like is applied to the substrate surface. Alternatively, a method of forming a specific structure on the polymer surface by using a stamper having a specific concave-convex pattern formed by etching a metal surface, or the like is also adopted.

As the substrate used in the present invention, various glasses such as soda glass, Pyrex glass and quartz glass, polyethylene terephthalate, polyethylene naphthalate, polyarylate, polyether sulfone, polyetherimide, polysulfone, polycarbonate, polymethyl. Methacrylate, polyethylene, polypropylene, polyimide, polyetheretherketone,
Examples of the plastic include polyphenylene sulfide, polyamide, polyvinylidene fluoride and the like. If necessary, one or both sides of the substrate may be covered with SiO 2.
₂ , SiO, SiON, SiO: H, SiN: H, Si
ON: H, Si ₃ N ₄ , TiO ₂ , ZnS, ZnO, Al ₂
O ₃ , AlN, MgO, GeO, ZrO ₂ , Nb ₂ O ₅ , S
A passivation film such as iC or Ta ₂ O ₅ can be formed. The thickness of the plastic substrate is 50 μm-2 mm
The one used is 500 μm or less, especially 300 μm
The following are preferred. Generally, the curl of the substrate is determined by the internal stress of the thin film formed on the substrate. Further, the thermal stress generated by the temperature at the time of forming a thin film also becomes a problem in a plastic film substrate having a large linear expansion coefficient.
Therefore, the liquid crystal driving element is formed on the plastic substrate,
In order to obtain a flat one, a substrate structure having a stress that cancels internal stress and thermal stress generated when a thin film laminated device is manufactured is required. When a substrate having a thin film made of an inorganic substance formed on both sides is used, a thin film made of an inorganic substance having a stress as shown in the following formula is required. Stress of liquid crystal driving element + stress of second inorganic material layer (2) = stress of first inorganic material layer (2 ′) When the first and second inorganic substances are of the same composition and of the same quality, the stress is a film. Since the thickness is determined by the thickness, it is easy to control the stress of the plastic substrate having the inorganic material formed on both sides by controlling the thickness of the inorganic material.

The liquid crystal driving element is a metal-insulator-
Metal layered MIM (Metal-Insulator)
r-Metal) type element, MSI (Metal-Semi-I) described in JP-A-61-275811.
SIS (Semiconductor-Insu) having a layer structure of a semiconductor element, an insulator, and a semiconductor.
Later-Semiconductor element, metal-insulator-metal-described in JP-A-64-7577.
There is an MIMIM element having an insulator-metal layer structure. Among them, the MIM element using the hard carbon film as the insulator is advantageous. When the hard carbon film is used as the insulating layer, the plastic substrate (film) is greatly curled. Therefore, it is necessary to form the inorganic material film on both sides of the substrate to increase the rigidity of the substrate.

MI when this hard carbon film is used as an insulating layer
A method of manufacturing the M element will be described based on FIGS. 1 and 2. The electrode material for pixel electrodes is vapor-deposited or sputtered on the coating layer 2 of the substrate 1 having both sides coated (2, 2 ') with the above-mentioned inorganic substance having fine irregularities only on the portions where the pixel electrodes 3 are provided. It is deposited and patterned into a predetermined pattern to form the pixel electrode 3. The surface of the pixel electrode 3 and the surface of the inorganic material are formed with fine irregularities that reflect the fine irregularities provided on the base. Next, a conductor thin film for the lower electrode is formed by a method such as vapor deposition and sputtering, and is patterned into a predetermined pattern by wet or dry etching to form a first conductor 3'which becomes the lower electrode. When both the pixel electrode and the lower electrode are used, one patterning can be deleted. After coating a hard carbon film thereon by a plasma CVD method, an ion beam method or the like, the insulating film 4 is patterned into a predetermined pattern by dry etching, wet etching or a lift-off method using a resist,
Then, a conductor thin film for a bus line is coated thereon by a method such as vapor deposition and sputtering, and patterned into a predetermined pattern to form a second conductor 5 serving as a bus line. When a transparent electrode is used for the pixel electrode 3, finally, an unnecessary portion of the lower electrode is removed to expose the transparent electrode pattern, and the pixel electrode 3 is formed. In this case, the configuration of the MIM element is not limited to this, and after the MIM element is manufactured, various modifications such as a pixel electrode provided on the uppermost layer and an MIM element formed on the side surface of the lower electrode are possible. Is. When the lower electrode 3 ′ has a thickness of several μm, the step of MIM becomes large and the element is likely to be broken. Therefore, the lateral structure in which the MIM element is formed on the side surface of the lower electrode is advantageous. Here, the lower electrode 3 ', the upper electrode 5 and the pixel electrode 3
The thickness is usually in the range of hundreds to thousands Å, hundreds to thousands Å, and hundreds to thousands Å, respectively. The thickness of the hard carbon film 4 is 100
˜8000 Å, preferably 200 to 6000 Å, and more preferably 300 to 4000 Å.

In the case of a plastic substrate, it has been very difficult to manufacture an active matrix device using an active element because of its heat resistance. However, a hard carbon film can be formed into a good quality film at a substrate temperature of about room temperature, and can be formed even on a plastic substrate, which is a very effective image quality improving means.

Next, the material of the MIM element used in the present invention will be described in more detail. The material of the lower electrode and the first conductor to be the pixel electrode is Al, Ta, Cr, W,
Mo, Pt, Ni, Ti, Cu, Au, W, ITO, Z
Various conductors such as nO: Al, In ₂ O ₃ and SnO ₂ are used. Next, as the material of the second conductor 5 which becomes the bus line, Al, Cr, Ni, Mo, Pt, Ag, Ti, C are used.
u, Au, W, Ta, ITO, ZnO: Al, In
Various conductors such as ₂ O ₃ and SnO ₂ are used, but IV
Ni, because of its excellent stability and reliability of characteristics
Pt and Ag are preferred. It is understood that the MIM element using the hard carbon film 4 as the insulating film does not change the symmetry even if the type of the electrode is changed, and the pool Frenkel type conductivity is obtained from the relation of 1nI∝√v. Also from this thing, this kind of M
In the case of the IM element, it can be seen that the upper electrode and the lower electrode may be combined in any manner. However, the device characteristics (IV characteristics) are deteriorated and changed due to the adhesion between the hard carbon film and the electrodes and the state of the interface. Considering these, Ni, P
It turned out that t and Ag are good. The current-voltage characteristics of the MIM element of the present invention are shown in FIG. 5, and are approximately expressed by the following conduction equation.

[0012]

[Equation 1]

I: current V: applied voltage κ: conductivity coefficient β:
Pool Frenkel coefficient n: Carrier density μ: Carrier mobility q: Electron charge Φ: Trap depth ρ: Specific resistance d: Hard carbon film thickness (Å) k: Boltzmann constant T: Atmospheric temperature ε ₁ : Hard carbon Dielectric constant ε ₂ : Vacuum dielectric constant As liquid crystal driving MIM elements, Ta ₂ O ₅ obtained by anodizing Ta and Al, MIM elements having Al ₂ O ₃ as an insulating layer, SiNx produced by plasma CVD, aC : An MIM element using H (hard carbon film) as an insulating layer is known.
Among them, MIM using a hard carbon film having a process temperature of 150 ° C. or less and a steepness of the element as an insulating layer is effective.

The hard carbon film that can be preferably used as the insulating layer of the MIM element will be described in detail below. An organic compound gas, particularly a hydrocarbon gas is used to form the hard carbon film. The phase state of these raw materials does not necessarily have to be a gas phase at room temperature and normal pressure, and may be a liquid phase or a solid phase as long as it can be vaporized through melting, evaporation, sublimation, etc. by heating or pressure reduction. is there. For the hydrocarbon gas as the raw material gas, for example, CH ₄ , C ₂ H ₆ , C ₃
Paraffinic hydrocarbons such as H ₈ and C ₄ H ₁₀ , acetylene hydrocarbons such as C ₂ H ₂ , olefinic hydrocarbons, diolefinic hydrocarbons, and all hydrocarbons such as aromatic hydrocarbons. At least gas containing can be used. In addition to hydrocarbons, compounds containing at least a carbon element such as alcohols, ketones, ethers, esters, CO and CO ₂ can be used. As a method for forming a hard carbon film from a source gas in the present invention, a method in which a film-forming active species is formed through a plasma state generated by a plasma method using direct current, low frequency, high frequency, or microwave However, since the deposition is performed under a low pressure for the purpose of increasing the area, improving the uniformity, and forming a film at a low temperature, a method of utilizing the magnetic field effect is more preferable.
Active species can also be formed by thermal decomposition at high temperature. Besides, it may be formed through an ionic state generated by an ionization vapor deposition method, an ion beam vapor deposition method, or the like, or may be formed from neutral particles generated by a vacuum vapor deposition method, a sputtering method, or the like. However, it may be formed by a combination thereof.

An example of the deposition conditions of the hard carbon film thus produced is as follows in the case of the plasma CVD method. RF output: 0.1 to 50 W / cm ² Pressure: 10 ^{−3 to} 10 Torr Deposition temperature: Room temperature to 350 ° C., preferably room temperature to 250 ° C. This plasma state causes the source gas to decompose into radicals and ions to react. By the carbon atom C on the substrate
A hard carbon film containing at least one of amorphous and microcrystalline (crystal size is several tens of .mu.m to several .mu.m) consisting of hydrogen atoms and hydrogen atoms H is deposited. Table 1 shows various characteristics of the hard carbon film.

[0016]

[Table 1]

Note) Measuring method: Specific resistance (ρ): Determined from IV characteristics of a coplanar cell. Optical bandgap (Egopt): From absorption characteristics to absorption coefficient
(α) is calculated and determined from the relationship of Equation 2.

[0018]

[Equation 2] Amount of hydrogen in film [C (H)]: 29 from infrared absorption spectrum
The peak near 00 / cm is integrated, and it is determined by multiplying by the absorption cross section A. That is, [C (H)] = A · ∫α (ν) / ν · dν SP ³ / SP ² ratio: the infrared absorption spectrum is decomposed into Gaussian functions assigned to SP ³ and SP ² , respectively, and Calculate from the area ratio. Vickers hardness (H): By micro Vickers meter. Refractive index (n): By ellipsometer. Defect density: According to ESR.

The hard carbon film thus formed is analyzed by Raman spectroscopy and IR absorption, and the results are shown in FIGS.
As shown in 8 and 8, hybrid orbitals with carbon atoms of SP ³ and SP ²
It has been clarified that the interatomic bonds forming the mixed orbitals of are mixed. The ratio of SP ³ bond to SP ² bond can be roughly estimated by separating peaks in the IR spectrum. IR spectrum shows 2800 to 3150 cm ^-1
The spectra of many modes are overlapped and are measured,
The attribution of the peaks corresponding to the respective wave numbers has been clarified. As shown in FIG. 5, the peaks are separated by the Gaussian distribution, the respective peak areas are calculated, and the ratio is calculated to obtain S.
You can know P ³ / SP ² . Further, it has been found by X-ray and electron diffraction analysis that it is in an amorphous state (a-C: H) and / or in an amorphous state containing fine crystal grains of about 50Å to several μm. Generally, in the case of the plasma CVD method suitable for mass production, the smaller the RF output, the more the specific resistance value and hardness of the film increase, and the lower the pressure, the longer the life of active species. The area can be made uniform, and the specific resistance and hardness tend to increase. Furthermore, at low pressure the plasma density decreases,
The method utilizing the magnetic field confinement effect is particularly effective for increasing the specific resistance. Furthermore, this method is also suitable for lowering the temperature of the MIM element manufacturing process because it has the characteristic that a good quality hard carbon film can be formed even under relatively low temperature conditions of room temperature to 150 ° C. Therefore, the degree of freedom in selecting the substrate material to be used is widened, and since the substrate temperature can be easily controlled, a uniform film can be obtained in a large area. Further, as shown in Table 1, the structure and physical properties of the hard carbon film can be controlled over a wide range, so that there is also an advantage that the device characteristics can be freely designed. Furthermore, the relative permittivity of the film is 2 to 6, which is Ta ₂ used in the conventional MIM element.
For O _5, Al ₂ O _3, small compared with SiNx, when making elements having the same capacitance, since the need to increase the element size, without the need for much fine processing, yield is improved (driving condition Therefore, the capacitance ratio between the LCD and the MIM element needs to be about C (LCD) / C (MIM) = 10: 1). Since the element steepness is β ∝ 1 / √ε · √d, the steepness increases as the relative permittivity ε decreases.
A large ratio of the on-current Ion and the off-current Ioff can be taken. Therefore, the LCD can be driven with a lower duty ratio, and a high-density LCD can be realized. Furthermore, since the hardness of the film is high, there is little damage due to the rubbing process when the liquid crystal material is filled, and the yield is improved from this point as well. In consideration of the above points, by using a hard carbon film, low cost, gradation (colorization), and high density LCD can be realized.
In addition to the carbon and hydrogen atoms, this hard carbon film is
It may contain a Group III element, a Group IV element, a Group V element, an alkali metal element, an alkaline earth metal element, a nitrogen atom, an oxygen element, a chalcogen element or a halogen atom as a constituent element of the periodic table. Periodic table No. 1 as one of the constituent elements
The group III element, the group V element, the alkali metal element, the alkaline earth metal element, the nitrogen atom or the oxygen atom introduced, the thickness of the hard carbon film is about 2 compared to the non-doped one.
The thickness can be increased to 3 times, and by this, the occurrence of pinholes at the time of manufacturing the element can be prevented and 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 the group IV element of the periodic table as described below is obtained. Similarly, Periodic Table IV
Introducing a group element, a chalcogen-based element or a halogen element dramatically improves the stability of the hard carbon film,
The hardness of the film is also improved, so that a highly reliable element can be manufactured. These effects are obtained because the active double bond existing in the hard carbon film is reduced in the case of the group IV element and the chalcogen element, and in the case of the halogen element, 1) the abstraction to hydrogen The reaction accelerates the decomposition of the raw material gas to reduce dangling bonds in the film, and 2) during the film formation process, the halogen element X abstracts hydrogen from the C—H bond and replaces it with C—X bond. This is because it enters the film and the binding energy increases (the binding energy between C-H and between C-X is larger between C-X). In order to use these elements as the constituent elements of the film, in addition to hydrocarbon gas and hydrogen as the source gas, a group III element, a group IV element and a group V element of the periodic table are contained in the film as a dopant. In order to contain an element, an alkali metal element, an alkaline earth metal element, a nitrogen atom, an oxygen atom, a chalcogen element or a halogen element, a compound (or molecule) containing these elements or atoms (hereinafter, these are referred to as `` other (Sometimes called "compound") gas is used. Examples of the compound containing a Group III element of the periodic table include B (OC
₂ H ₅ ) ₃ , B ₂ H ₆ , BCl ₃ , BBr ₃ , BF ₃ , Al (O-i-C
₃ H ₇ ) ₃ , (CH ₃ ) ₃ Al, (C ₂ H ₅ ) ₃ Al, (i-C ₄ H ₉ ) ₃ A
_{l, AlCl 3, Ga (O} -i-C 3 H 7) 3, (CH 3) 3 Ga, (C
_{2 H 5) 3 Ga, GaCl} 3, GaBr 3, (O-i-C 3 H 7) 3 In,
(C ₂ H ₅ ) ₃ In and the like. Examples of the compound containing a Group IV element of the periodic table include Si ₂ H ₆ , (C ₂ H ₅ ) ₃ SiH, Si
F ₄ , SiH ₂ Cl ₂ , SiCl ₄ , Si (OCH ₃ ) ₄ , Si (OC _{2
H 5) 4, Si (OC} 3 H 7) 4, GeCl 4, GeH 4, Ge (OC 2
_{H 5) 4, Ge (C} 2 H 5) 4, (CH 3) 4 Sn, (C 2 H 5) 4 Sn, Sn
There are Cl ₄ etc. Examples of the compound containing a Group V element of the periodic table include PH ₃ , PF ₃ , PF ₅ , PCl ₂ F ₃ , PCl ₃ and P
Cl ₂ F, PBr ₃ , PO (OCH ₃ ) ₃ , P (C ₂ H ₅ ) ₃ , PO
Cl ₃ , AsH ₃ , AsCl ₃ , AsBr ₃ , AsF ₃ , AsF ₅ , A
There are sCl ₃ , SbH ₃ , SbF ₃ , SbCl ₃ , Sb (OC ₂ H ₅ ) _{3 and the} like. As the compound containing an alkali metal atom, there is for example _{LiO-i-C 3 H 7} , NaO-i-C 3 H 7, KO-i-C 3 H 7 or the like. Examples of the compound containing an alkaline earth metal atom include Ca (OC ₂ H ₅ ) ₃ , Mg (OC ₂ H ₅ ) ₂ and (C ₂ H ₅ ) ₂ Mg. Examples of the compound containing a nitrogen atom include an inorganic compound such as nitrogen gas and ammonia, an organic compound having a functional group such as an amino group and a cyano group, and a heterocycle containing nitrogen. Examples of the compound containing an oxygen atom include oxygen gas, ozone, water (water vapor), hydrogen peroxide, carbon monoxide,
Inorganic compounds such as carbon dioxide, carbon suboxide, nitric oxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen pentoxide, nitric oxide, hydroxyl group, aldehyde group, acyl group, ketone group, nitro group, nitroso group, sulfone Examples thereof include organic compounds having functional groups or bonds such as groups, ether bonds, ester bonds, peptide bonds, oxygen-containing heterocycles, and metal alkoxides. Examples of the compound containing a chalcogen-based element include H ₂ S, (CH ₃ ) (CH ₂ ) ₄ S (CH ₂ ) ₄ CH ₃ ,
CH ₂ = CHCH ₂ SCH ₂ CH = CH ₂ , C ₂ H ₅ SC
₂ H ₅ , C ₂ H ₅ SCH ₃ , thiophene, H ₂ Se, (C ₂ H ₅ ) ₂
Se, H ₂ Te, etc. are available. Examples of the compound containing a halogen element include fluorine, chlorine, bromine, iodine, hydrogen fluoride,
Carbon fluoride, chlorine fluoride, bromine fluoride, iodine fluoride, hydrogen chloride,
Inorganic compounds such as bromine chloride, iodine chloride, hydrogen bromide, iodine bromide and hydrogen iodide, and organic compounds such as alkyl halides, aryl halides, styrene halides, polymethylene halides and haloforms are used. Liquid crystal drive MIM
A hard carbon film suitable as an element has a thickness of 10 depending on driving conditions.
Advantageously, it has a specific resistance of 0 to 8000Å and a specific resistance of 10 ⁶ to 10 ¹³ Ω · cm. Drive voltage and breakdown voltage (dielectric breakdown voltage)
In consideration of the margin with, it is desirable that the film thickness is 200 Å or more. Also, in order to prevent color unevenness due to the step (cell gap difference) between the pixel part and the thin film two-terminal element part from becoming a practical problem. Since the film thickness is preferably 6000Å or less, it is more preferable that the hard carbon film has a film thickness of 200 to 6000Å and a specific resistance of 5 × 10 ⁶ to 10 ¹³ Ω · cm. The number of defects in the device due to pinholes in the hard carbon film increases as the film thickness decreases, and becomes particularly noticeable below 300 Å (the defect rate exceeds 1%), and the in-plane distribution of the film thickness is uniform. Therefore, it is more desirable that the film thickness is 300 Å or more, because it is not possible to secure the uniformity (and eventually the uniformity of device characteristics) (the accuracy of film thickness control is limited to about 30 Å, and the variation in film thickness exceeds 10%). . Further, in order to prevent the hard carbon film from peeling off due to stress and to drive at a lower duty ratio (desirably 1/1000 or less), the film thickness is more preferably 4000 Å or less. Taking these factors into consideration, it is more preferable that the hard carbon film has a film thickness of 300 to 4000 Å and a specific resistance of 10 ⁷ to 10 ¹¹ Ω · cm.

Next, a method of manufacturing a liquid crystal display device will be described with reference to FIG. First, a transparent conductor for the common electrode 9, for example, ITO, ZnO: Al, ZnO: Si, Sn is formed on the insulating substrate 10.
A common electrode 9 is formed by depositing O ₂ , In ₂ O ₃ or the like by sputtering, vapor deposition or the like by several hundred liters to several μm, and patterning them in stripes. An alignment material such as polyimide is attached to the surface of each of the substrate 10 on which the common electrode 9 is provided and the substrate 1 on which the MIM elements are previously provided in a matrix shape, a rubbing process is performed, a sealing material is attached, and a gap material is inserted. The gap is made constant by enclosing the liquid crystal 3 in the liquid crystal display device.
In this way, a liquid crystal display device is obtained. When a polymer-liquid crystal composite is used for the liquid crystal 3 and a light scattering mode display is formed, it is not necessary to provide an alignment material. Polymer
As the polymer material in the liquid crystal composite, polymethylmethacrylate, polystyrene, polyfumarate, polyethylene oxide or the like can be used. Of these, polyfumarate, which is a rigid polymer, is preferable. As the liquid crystal material, TN liquid crystal or the like which has been used for the conventional liquid crystal display can be used. The structure of the polymer-liquid crystal composite includes a system in which liquid crystal is dispersed in a droplet form in the polymer and a system in which liquid crystal forms a continuous phase in the polymer. Either system can be used in the present invention. These composite layers can be prepared by casting a polymer-liquid crystal solution using chloroform as a solvent. It can also be produced by a method in which a monomer and liquid crystal are mixed and then light is aggregated.

[0021]

EXAMPLES Examples of the present invention will be described, but the present invention is not limited to these examples. Example 1 A portion other than the pixel electrode pattern was resist-coated on a polyethylene terephthalate film containing a filler having a thickness of 100 μm, and plasma-treated with Ar gas at 0.1 torr. As a result, the non-resist coating portion is shown in FIG.
The unevenness as shown in (b) was formed. Next, a 6000Å thick SiO ₂ sputtered film was formed on both sides of the film. Next, an Al thin film was deposited on SiO ₂ to a thickness of 1000 Å by vacuum evaporation, and then patterned to form a pixel electrode and a lower electrode of MIM at the same time. Further, as the insulating layer 4, a hard carbon film was deposited to a thickness of 1000 Å by the plasma CVD method and then patterned by dry etching. The conditions for forming the hard carbon film at this time are as follows. Pressure: 0.035 torr CH ₄ Flow rate: 10 SCCM RF power: 0.2 W / cm ² Further, Ni was deposited thereon by EB vapor deposition to a thickness of about 1000 Å and patterned to form the upper electrode 5, thereby forming an MIM element. Was completed. Next, 700 Å of transparent conductor ITO for the common electrode 9 is deposited on the insulating substrate 10 by sputtering and patterned in a stripe shape to form the common electrode 9
And Next, an E8 chloroform solution containing polyfumarate and a black dye was cast on the substrate 1 provided with the MIM element, and a polymer-liquid crystal composite film was provided by a solvent evaporation method. Next, the liquid crystal display device was laminated with the common electrode substrate 10. The liquid crystal display device manufactured as described above can obtain a bright and high-definition display without a backlight, and since it is lightweight and thin, it has excellent impact resistance and flexibility. Moreover, since a reflector and a transparent pixel electrode are not required, the yield is improved and the cost is reduced.

Example 2 A 2 μm thick Al sputtered film having a specular reflectance of 0% was deposited on a glass substrate at a N ₂ partial pressure of 2 × 10 ⁻³ torr and a substrate temperature of 100 ° C., and then patterned to form a pixel electrode. . Next, a MIM element having a lateral structure was formed on the side surface of the Al pixel electrode by the same process as in Example 1. Next, a liquid crystal display device was manufactured in the same manner as in Example 1. The liquid crystal display device manufactured as described above can obtain a bright and high-definition display without a backlight and does not require a reflector or a transparent pixel electrode, so that the yield is improved and the cost is reduced. Also, M
By using IM as a lateral structure, it became possible to fabricate a smooth surface (side surface), and the reliability of the device was secured.

[0023]

【effect】

(1) Since the liquid crystal display device of the present invention doubles as a pixel electrode and a light scattering layer, it is possible to provide a bright and high-definition liquid crystal display device with improved yield and reduced cost. (2) The substrate used in the liquid crystal display device of the present invention can be easily produced by plasma-treating a polymer material substrate containing a filler or dispersed with inorganic fine particles, and a lightweight and flexible liquid crystal display device can be provided. (3) In the liquid crystal display device of the present invention, by using the lateral type MIM element, it is possible to connect the reliable MIM element to the pixel electrode having the uneven surface. (4) Since the liquid crystal display device of the present invention is a light-scattering type liquid crystal display device using a polymer-liquid crystal composite film as liquid crystal, it enables bright and high-definition display without a backlight. (5) MI using a hard carbon film as an insulating layer for a liquid crystal driving element
When the M-type element is used, the hard carbon film is formed by 1) a vapor phase synthesis method such as plasma CVD method, so that the physical properties can be controlled widely depending on the film forming conditions, and thus the degree of freedom in device design is large. ) Since it is hard and can be thick film, it is less susceptible to mechanical damage, and it can be expected to reduce pinholes due to thicker film. 3) Good quality film can be formed even at low temperature near room temperature, so substrate material is restricted 4) It is suitable for thin film devices because it has excellent uniformity in film thickness and film quality. 5) It has a low dielectric constant, so it does not require high-level microfabrication technology, and therefore has a large element area. In addition, since the element has a high steepness due to its low dielectric constant and a high Ion / Ioff ratio, it can be driven at a low duty ratio, and so on. Suitable as a switching element for liquid crystal display A.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a substrate configuration of a liquid crystal display device of the present invention.

FIG. 2 is a perspective view of a MIM liquid crystal driving element used in the present invention.

FIG. 3 is a diagram schematically showing a state of forming irregularities when a filler-containing polymer substrate is subjected to etching treatment. (A) It is a figure which shows typically the cross section of a polymer film substrate containing a filler. (B) It is a figure which shows typically the cross section of the said substrate at the time of etching the substrate of said (a) at a low speed. (C) It is a figure which shows typically the cross section of the said board | substrate when the board | substrate of said (a) is etched at high speed.

FIG. 4 is a diagram schematically showing a state of forming irregularities when a polymer substrate on which inorganic fine particles are dispersed is subjected to an etching treatment. (A) It is a figure which shows typically the cross section of the polymer substrate in which the inorganic fine particle was scattered. (B) It is a figure which shows typically the cross section of the said substrate at the time of etching the substrate of said (a) at a low speed. (C) It is a figure which shows typically the cross section of the said board | substrate when the board | substrate of said (a) is etched at high speed. The inorganic fine particles are removed after etching.

5A is a diagram showing an IV characteristic curve of the MIM element of the present invention, and FIG. 5B is a diagram showing an lnI-√V characteristic curve of the MIM element.

FIG. 6 is a diagram showing a Gaussian distribution of IR spectrum of a hard carbon film used as an insulating layer of the MIM element of the present invention.

FIG. 7 is a spectrum diagram showing the analysis results of the Raman spectrum analysis of the hard carbon film used for the insulating layer of the MIM element of the present invention.

FIG. 8 is a spectrum diagram showing an analysis result obtained by analyzing a hard carbon film used as an insulating layer of the MIM element of the present invention by an IR absorption method.

FIG. 9 is a diagram schematically showing a cross section of a lateral structure MIM element used in the present invention.

[Explanation of symbols]

 1 substrate 2 passivation film 2'passivation film 3 pixel electrode 3'lower electrode 4 hard carbon insulating film 5 upper electrode (second conductor) 6 polymer phase 7 liquid crystal phase 8 dye 9 common electrode 10 substrate 11 incident light 12 reflected light 13 Filler 14 Polymer film 15 Inorganic fine particles 16 Polyimide

Claims (7)

[Claims] 1. In an active drive type liquid crystal display device having a structure in which a liquid crystal layer is sandwiched between a pair of substrates provided with liquid crystal drive electrodes, a pixel electrode formed on one substrate also functions as a light scattering layer. A liquid crystal display device characterized by the above. 2. The liquid crystal display device according to claim 1, wherein the pixel electrode has an uneven surface. 3. The liquid crystal display device according to claim 1, wherein the pixel electrode is provided on a substrate on which fine irregularities are formed. 4. The liquid crystal display device according to claim 1, wherein the substrate on which at least the pixel electrode is provided is made of a polymer material is used as the substrate. 5. A liquid crystal driving element having M having a lateral structure.
The liquid crystal display device according to claim 1, which is an IM element. 6. The liquid crystal display device according to claim 5, wherein the insulating film of the MIM element is formed of a hard carbon film. 7. A polymer / liquid crystal dispersion layer that changes between a state in which light is scattered and a state in which light is transmitted depending on whether a voltage is applied to the liquid crystal layer or not. It is comprised, Claim 1, 2, 3,
The liquid crystal display device according to 4, 5, or 6.