JPS5852680A - Manufacture of liquid crystal panel substrate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing an IJ square type liquid crystal panel substrate, and more particularly to a method for manufacturing an active matrix IJ square type liquid crystal panel substrate using a non-linear resistance element.

In recent years, the application of TN type liquid crystal display devices R has progressed, and they are now being used in large quantities in the fields of wristwatches, calculators, and the like.

In order to expand the field of application of this liquid crystal display device, it is necessary to increase the display capacity, but conventional TN type liquid crystal display devices are sandwiched between two polarizing plates whose polarization axes intersect at approximately 90 degrees. In a method in which a nematic liquid crystal is sealed between two substrates with transparent electrodes so that its molecular axis is twisted, and display is performed by electric field effect, the rise of the voltage-contrast characteristic is not very steep, making it difficult to use multiplex drive. As the number of digits is increased, crosstalk occurs in which half-selected points begin to light up, and multi-digit driving of several tens of digits is the limit.

Therefore, in order to increase the display capacity of liquid crystal display devices, active polymer (IJ) type devices using non-linear elements have been considered, and various devices such as TFTs and diodes made of amorphous silicon or polysilicon, or varistors made of zinc oxide, etc. have been considered. approaches are being taken. Among them Baraf
f, D, R, et, #A, .

(From 1980S International
l Symp.

eium Digest of Tech, n1
cal Papers.

Vol, X Engineering, P, 200, April
A nonlinear resistance element using an oxide film of tantalum or tantalum nitride according to I980) has the advantage that the manufacturing process is relatively simple and the element design is easy. The basic structure of this device is as shown in FIGS. 1 and 2. A glass substrate 1 is coated with a Ta2O film 2, a Ta thin film or a nitrogen-doped TaN film 3 is sputtered, and the surface is patterned into a predetermined shape. is subjected to @polar oxidation to form an oxide film 4. A rough N i -Or and Au thin film is deposited and patterned to form the counter electrode 5 . A transparent 'rIi electrode 6 made of Ni-Or and Au is attached so as to be electrically conductive with this counter electrode 5. In order to make a display device, the transparent electrodes 6 are arranged in a matrix as shown in FIG.
A TN panel is made by sealing liquid crystal between the substrate and a counter substrate having a plurality of striped transparent electrodes perpendicular to the substrate.

This element (convenience) - Metal - Engineering n5ulator
-Metal (abbreviated as IA M element), that is, Ta thin film or nitrogen-doped Ta thin film 3 and N
When a voltage is applied between the opposing electrodes 5 of the i Or / Au thin film, a nonlinear voltage-■-current characteristic is obtained as shown in Fig. 4, and the relationship is expressed as follows: 1) [In the formula, K9β
is a coefficient] which corresponds to the equation expressing the Poole −Frθn, k e l effect.

When dynamically driving the TN panel that combines this M element and liquid crystal, the effective value ratio of the ON voltage actually applied to the liquid crystal and the pressure becomes large due to the nonlinearity of the M element. According to Baraff et al., 1/100-1
/200 duty dynamic drive can be easily achieved.

However, the M element constructed by Baraff et al. has two different metal-oxide film interfaces: a Ta thin film or a nitrogen-doped Ta thin film, an anodic oxide film of the same thin film, and (Ni, -Or/ A u ) There are two thin film interfaces through which current flows, so when the polarity of the voltage applied to the M element changes, the voltage-current characteristics become asymmetric. For this reason, even if a symmetrical alternating signal is applied to a TN panel using M technology and M elements, the waveform directly applied to the liquid crystal becomes asymmetric, and a DC component remains, which does not significantly affect the life of the panel.

Furthermore, when driving a TN panel using MIM elements, M
The equivalent circuit of the I'M element and the TN panel is shown in Figure 6.The M element 8 has the capacitance OMfM and the non-linear resistor external RMIM in parallel, and the capacitive OLO and the external resistor RLO are in parallel. It is considered that the liquid crystal portions 9 are connected in series. A driving voltage is applied to both ends of this, but the effective voltage actually applied to the liquid crystal 9 is influenced by the combination of the capacitance OMIM of the M element 8 and the capacitance OLO of the liquid crystal 9, so let's calculate it. When the value of the capacitance OMKM of the MIM element 8 is smaller than the capacitance QLOO value of the liquid crystal 9, the range of characteristics setting of the M element 8 becomes wider, and the value of the capacitance ratio OLO/OMI M becomes 5. ~20
In terms of degree, the larger the value is 1.

In the design of Baraff, D, R, et al.
While the M element has dimensions of 12μ×12μ, the liquid crystal portion (pixel) has a pitch of 125H, which is quite rough. In the dot matrix liquid crystal panels actually used in various devices, a pitch of 0.3 to 0.5 mm is often adopted, so if an M element with the same configuration is designed, the pitch is 6 to 5 μm.
This is the corner dimension.

In order to make the optical characteristics of the entire liquid crystal panel uniform, it is necessary that the characteristics of each M element within the substrate be the same, but the size range of 3 to 5 μm is not possible with current mask aligners. It is close to the boundary area between micropattern processing (for vr, sI) and fine pattern processing (for vr, sI).

Therefore, in order to align the characteristics caused by the area of each element, a higher-precision mask aligner is required, and especially when trying to increase the size of a TN liquid crystal panel incorporating M-process M elements, the manufacturing cost of M-process M elements increases. did not have a major impact on

In order to eliminate this drawback, the present invention connects two M-engine M elements in series in a direction that complements the asymmetry of the voltage-current characteristics, thereby obtaining symmetrical voltage-current characteristics. By utilizing the fact that the same capacitance value can be obtained with double the area per MIM element compared to when one MIM element is used, the pattern accuracy required in the photolithography process is made more relaxed.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 7 and FIG. 8 show an embodiment of the manufacturing process for the M element. FIG. 7 is a sectional view, and FIG. 8 is a plan view.

The substrate 11 is made of so-called glass such as soda glass, pyrex glass, or quartz glass.

In order to improve the adhesion between the glass substrate 11 and the metal formed in the subsequent process, in the case of soda glass containing alkali metals, heavy metals, etc., the metal contained in M.
Since it is thought that it will have an adverse effect on the device characteristics and the liquid crystal, a metal oxide film is used as a passivation film for the substrate.
It may be formed by a position method or a sputter deposition method. In this example, considering the above reasons, Ta2
O.

A film 12 is then formed. Next, Ta13 is formed to a thickness of 1000 to 4000× by sputtering or the like, and patterned by photoetching. Etching can be performed by plasma etching using OF or OF gas containing 02. Although Ta is used in this example, the material other than Ta may be any metal that is normally used for M elements. It can be used. The Ta pattern 13 is connected to each Ta pattern 13 (metal pattern to be anodized) as shown in FIG. 9 in order to establish electrical continuity with each Ta pattern 13 (metal pattern to be anodized) in the anodizing process to be performed in the subsequent process. good. After patterning the Ta thin film, the surface of Ta 13 is oxidized by anodic oxidation in a citric acid aqueous solution to form an insulator film 14. The thickness of the anodic oxide film is proportional to the applied voltage, and is about 300 mm at 20 V. After the anodic oxidation, the necessary portions of the pattern made of Ta and Ta 20 H are left, and the others are removed by photo-etching or the like. After forming an insulating film on the Ta surface, heat treatment can improve the quality of the anodic oxide film, the quality of the metal film on top of the oxide film formed in the subsequent process, or the interface state between the oxide film and the metal film. Furthermore, the adhesion of the upper metal film can be improved.

Due to the above effects, it is necessary to perform heat treatment, and the above effects can be obtained by performing heat treatment at a temperature of 200°C or more and 500°C or less in an atmosphere of N2 gas, 0° gas, or a mixed gas of N2 and 02. . Thereafter, a Ta thin film 15 is formed by sputter deposition or the like. Ta
N1g, % 15 in place of metals used in M-tech M elements, such as Ta, W doped with chino.

A L, T i, M o, Or, N
It may also be a metal such as iOr. Film thickness is 3001~4000
Let it be X. If it is more than 40 ooX, cracks may occur due to stress, and if it is made thinner, the resistance will increase or the wire will break at the stepped portion. Ta15 is patterned into a desired shape by photoetching. At this time,
Not shown in FIG. 8: J: Sea urchin M 1M elements are arranged in series and with polarities in opposite directions. At this time, each II engineering M”J4
Wiring 15 connecting the children is also formed at the same time. Moreover, by doing as shown in FIG. 8, even if Ta15 is slightly misaligned with respect to Ta13, there is no change in the dimensions of the M x rIIIg element, and there is a margin for alignment accuracy, and a drop in yield due to poor alignment can be prevented. Through the above steps, a substrate in which MIM elements connected in series are arranged in a 7-trix pattern is produced. Furthermore, a transparent electrode 16 is formed to form a liquid crystal panel substrate.
By connecting M elements in series, it is possible to create a liquid crystal panel substrate arranged in a matrix. The transparent NU electrode 16 is made of In, O, which is used in ordinary liquid crystal panels.

SnO2, To (to) pdium -Tj, n -Ox
j, de). In this example, the engineering To is approximately 300X
MIMs are sputter-deposited and connected in series as shown in Figure 8.
Pattern it so that it is connected to one end of the element. The quality of a transparent conductive thin film can be improved by heat treatment. As a heat treatment method, the substrate is heated during film formation by sputter deposition or OvD, or heat treatment is performed in an air atmosphere or N atmosphere after film formation or patterning. The higher the heat treatment temperature, the better the film quality, and a suitable heat treatment temperature is 100°C to 500°C. In this example, the temperature was 120°C. In order to create a liquid crystal panel substrate, we further employ the methods commonly used to orient liquid crystals, such as rubbing, oblique evaporation of inorganic substances such as SiO, and coating of organic compounds such as polyimide, organic silane compounds, and Teflon. Then, a liquid crystal panel substrate is obtained by rubbing it as an alignment film and forming a liquid crystal panel substrate.In this way, a liquid crystal panel substrate can be obtained in which each pixel has an M element connected in series. Even when the characteristics are asymmetric due to their polarities, according to the present invention, two M elements are connected in series in a direction that complements the asymmetry of the voltage-current characteristics, so symmetrical voltage-current characteristics can be achieved. I was able to get it.

[Brief explanation of drawings]

Figures 1, 2 and 34
f. The structure of the M element of D, R, etc. is shown, and FIG. 4 shows its voltage-current characteristics. FIG. 5 shows the difference in pressure contrast characteristics of a liquid crystal display device when an M element is not used and when an M element is used. FIG. 6 shows a circuit of one pixel of a liquid crystal panel incorporating an M.times.M element. Figures 7 (a,) to (f) and 8 [Flash (α) to (f)
1A and 1B are a cross-sectional view and a plan view showing a method of manufacturing a liquid crystal panel substrate having M elements connected in series according to the present invention. The 91st example is a wiring jump for anodic oxidation. Applicant Suwa Seikosha Co., Ltd. Agent Patent Attorney Mugo Mogami Figure 1

Claims (9)

[Claims] (1) A step of forming a first conductor thin film on an insulating substrate and then selectively etching it to pattern the first conductor 11 into a predetermined shape, and anodizing the first conductor thin film. a step of wrapping the surface of the first conductor thin film with an oxide film of the first conductor, and a step of selectively etching the first conductor thin film and the oxide film of the first conductor to pattern it into a predetermined shape. a heat treatment step after the patterning after the anodic oxidation; a collation step of forming the second conductive thin film and then selectively etching the second conductive thin film to pattern it into a predetermined shape; 1. A method for manufacturing a liquid crystal panel substrate, comprising the steps of forming a third conductive thin film and then selectively etching a third conductive thin film to pattern it into a predetermined shape. (2) The insulator substrate is made of so-called glass such as soda glass, pyrex glass, quartz glass, or
2. The method of manufacturing a liquid crystal panel substrate according to claim 1, wherein the substrate is an insulating substrate in which an oxide of a first conductor is formed on the glass surface. (3) The first conductive thin film is Ta, Or, W or A
100% by sputter deposition etc.
The liquid crystal panel L (method for manufacturing a plate) according to claim 1, characterized in that the film thickness is 0 to 40,001. (4) The anodized film thickness of the first conductor is 100 to 100
2. A method for manufacturing a liquid crystal panel substrate according to claim 1, wherein the liquid crystal panel substrate is 0. (5) The second conductive thin film is Ta, W, At, or Ti. The method for manufacturing a liquid crystal panel substrate according to claim 1, characterized in that the film is made of any one of Mo, Or, and Nior alloys and is made to have a film thickness of 300 to 4000X by sputter deposition or the like. (6) When the third conductor is installed n20. ．． SnO,,■T. Alternatively, the liquid crystal panel substrate according to the above item 1 is made of a transparent conductor made of a thin metal film. (7) The heat treatment after anodizing is performed at 200°C or higher with N2 gas 902 gas or a mixed atmosphere of N2 and 02 uH gas.
The method for manufacturing a liquid crystal panel substrate according to claim 1, wherein the temperature is 00°C or less. (8) A liquid crystal panel substrate according to claim 1, characterized in that the transparent conductor thin film is formed by sputter deposition or 0D method, and the substrate is heated at 100°C to 500°C during film formation. Production method. (9) The method for manufacturing a liquid crystal panel substrate according to claim 1, wherein after forming the transparent conductor thin film, heat treatment is performed at 100°C to 500°C in N2 or air atmosphere.