JPS5879281A - Matrix type liquid crystal display - 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 display device fK using liquid crystal.

More specifically, a matrix type liquid crystal display #KH is a liquid crystal display device in which non-linear elements are combined to improve display characteristics.

In recent years, the application of LCD displays has progressed, and by taking advantage of their low power consumption and ability to make the display section thinner, they have come to be used in large quantities as display devices for small electronic devices such as wristwatches and calculators. became.

In order to further expand the field of application of this liquid crystal display device It5, it is necessary to increase the display capacity.1 In the conventional TN type liquid crystal display device, the rise of the voltage-contrast characteristic is not very steep, so the multi-break When the number of digits is increased, the difference between the effective voltages applied to the non-selected point or half-selected point and the selected point decreases, causing tallostoke, so that multi-digit driving of several digits becomes common. One way to overcome these disadvantages is to combine nonlinear elements or switching elements with liquid crystal display devices. Various studies have been made, including the use of varistors using materials such as diodes, zinc oxide, etc.

Among such nonlinear elements, Japanese Patent Application Laid-Open No. 52-149090
and JP-A-55-16127!5, the metal-insulator-metal (Mstal-Xnaulato
A non-wire element (hereinafter referred to as an MIM element) having an r-Mstal (abbreviated as MIM) structure has a simple element configuration, so compared to other non-linear elements, the manufacturing process II is shorter and the element design is easier. It is thought that current flows in this MIM device due to the tunnel effect, Schottke effect, or Boer-Frenkel effect, and as shown in Figure 1, the nonlinear voltage-W current flow is controlled by the MIM device. Show your gender.

Insulator A7, Ta, Nb, Ti
, 81, Mo, W.

An acid oxide of Ht@, an oxide of the above-mentioned metal doped with nitrogen, a non-contact material such as a chalcogenide glass cape, and an organic material such as a transparent polyimide resin cape can also be used.

An MTM structure can be obtained by sandwiching the insulating layer with metal, and the metals include the metal and Ni.

By using Cr, ^U or their alloys
−”ru.

When a voltage is applied to a MIM element, the conduction mechanism differs depending on the thickness of the insulating film.For 50 to 100λ, the Door*le effect is dominant, while for 100 to 1000, the Schottke effect and Poole-Frenkel effect are dominant. In the combination of the present liquid crystal display device and the M element, which is said to be the aim and target of the present invention, it is desirable to utilize the region exhibiting the Boo^-Frengal effect in view of the liquid crystal driving method. In that region, the voltage-current characteristic is Poole Frenkel height = kV exp (βJ'V)
It is expressed as (1).

When a liquid crystal display device incorporating this MIM element is driven using the voltage averaging method used to drive a normal matrix type liquid crystal display device, the non-linearity of the IM element causes the voltage actually applied to the liquid crystal to decrease. The N10ff effective value ratio is larger than the ON10FF effective value ratio of the voltage averaging method itself.
, when a 1M V element, which enables multi-digit matrix drive, is combined with a liquid crystal display device, the equivalent circuit for one pixel is as shown in Figure 2, where the capacitance Q MIM and the non-cylindrical resistance R are
MIIM is connected in parallel with M element 1 and capacitance 0.
2 is obtained by considering that the liquid crystal portion 2 in which the resistor R- and the resistor R- are connected in series.

A voltage is applied to both ends of this H, but the effective voltage actually applied to the liquid crystal section 2 is λ (time constant of TM element 10, time constant of liquid crystal section 20, and capacitance Q of MIM element 1)
M! Ratio between M and QLO for 1/2 liquid crystal capacity O・L O/
It is determined by the combination with QMIM, and the time constant of the liquid crystal part 2 and the value of OLO/CMIM are large (and the time constant of the MUM element 10 has an appropriate value, the time effective voltage will be the largest. The larger the nonlinearity of 1, the more digits can be obtained for matrix driving.

Here, to clarify the structure of the conventional M'' process M element, for example, as shown in FIGS. 3 and 4, a glass substrate 3 is coated with an oxide film 4 to serve as an etch stop, and then a gold film 5 is formed. ,
After patterning the metal thin film 5 to a desired shape, an insulator thin film 6 is formed on the surface.

Further, a metal thin film is formed and patterned to form the opposing electrical connection 7 of the MIM element. At this time, the Lii product of the MIM element is the area of the portion where the metal electrode 5 and the counter electrode 7 overlap each other. To make a liquid crystal display device, next, the pixel electrode 8 is formed using a transparent conductive electrode, and a liquid crystal alignment layer is formed on the surface to maintain a constant level. The opposite substrate with a gap maintained is used as a cell, and between them l! A liquid crystal is sealed in I, a polarizing plate is attached, and a TNN liquid crystal display is installed.

When creating a matrix-type liquid crystal display device using MIM elements with such a structure, conventional matrix-type liquid crystal display device v often uses pixel dimensions of α3 to α5 pitch, and such dimensions The size of the MIM cable corresponding to the pixel is 3 to 6srnp. In the current photolin graph contact, this 3 to 6 prn square 2 dimension area is the boundary area between L8 and VLSI, and since it is a matrix layer display device, the display part size is 5 to 6 prn square.
It is very difficult to form an element with the size of 7e, and it has pixels of even smaller dimensions! Complete KVL when trying to make a trix type liquid crystal display device.
BVLSI technology must be used, which is not desirable in terms of cost.

On the other hand, in addition to dimensional problems when manufacturing MIM elements, conventional MIM
It is very difficult to obtain a symmetrical device using the reverse control method of an IM device, and the voltage applied to a 1M IM device is extremely difficult due to the irregularity of the interface between the metal oxide film and the oxide film used as an insulator. It has an asymmetrical property in that the v-r characteristics change depending on the polarity of the polarity.If the liquid crystal is driven with a symmetrical alternating waveform through a νIM element with such asymmetrical characteristics, an asymmetrical alternating waveform is applied to the liquid crystal. As a result, a direct current component remains, significantly shortening the life of the liquid crystal display device.

The present invention is to devise a novel method for manufacturing MTM elements.
To obtain a MrM element with a smaller area and at the same time to use two MIM elements and connect them in series in a direction that cancels out the asymmetry of each other to obtain symmetrical V-1 characteristics and to extend the life of the liquid crystal display device. It is.

The present invention will be explained below with reference to Examples.

Example 1 Pyrex glass substrate 9 top 1c In, O, 8nO
,.

To(Work n, 0.+ Bn02>or FiNi O
The pixel electrode 1o is formed of a transparent conductive film such as r/AU thin film. →Figure 5←) Next K 10 (10 to 10,000 JI thick tantalum material is shaped and patterned into a predetermined shape, then the grain surface is oxidized and the lead part and one metal electrode 11 of the MIM element are tightened.)
form 12. →Fig. 5 6) When patterning tantalum, add 5 to 5 liters of Gaga gas to C1 Ganu.
〇-Mixing and plasma etching Perform taper etching of tantalum.

Next, a zinc oxide thin film layer 13 of K15Qn~YanoX and a positive resist layer 14 of about 1~271m thick are formed on the entire surface. When exposure is performed from the opposite side of the resist layer 140, the lead portion and the tantalum portion of the metal electrode 11 of one of the M elements act as a mask, and in the worst case, the resist 14 remains as shown in FIG. 5(a). .

Next, the zinc oxide thin film layer 15 is etched to form the structure shown in FIG. 5 (.). At this time, the etching conditions of the zinc oxide thin film layer 13 are controlled to control the side etching amount to 1000~1000
Let it be oooX.

Next K 1000~1ooooK shore K Ni Or/
^U thin film 15 is formed. →Figure 5 (t) At this time,
The taper of the metal electrode 11 and the insulating film 12 on one side of the lead part and the MXM element [b t-r] is a method that increases the step coverage (e.g., using a vapor deposition method using a rotation-revolution type substrate mounting jig, or using sputtering). If you use ``Itasho'', it will be faint.

Next, the residual portion of the zinc oxide thin III layer 13 is removed, and the upper resist layer 14 and the Ni0r/^U thin film 15sl are removed to obtain the state of the fifth recirculation.
While removing unnecessary parts of the Or/Au thin film 15 to complete the MIM device, the 1iii elementary electrode 10 is exposed.
→FIG. 5(h) At this time, an example of the planar layout of the completed MIM element and the pixel electrode 10 is shown in FIG.

The area of the MIM element is determined by the length of the tapered portion of the insulating film 12 and the width of the tJior/-u thin film 15 of the counter electrode.

A polyimide resin is coated on the surface of the Pyrex glass substrate 9e on which the IIIM element and the pixels 115 are formed, and the polyimide resin is rubbed with a cotton cloth to perform a liquid crystal alignment treatment. A Pyrex glass-to-meat 1# plate 17 which has been subjected to liquid crystal V-direction treatment by rubbing is prepared and adhered with a gap of 15 to 20 μm, and the liquid crystal 18 is inserted. At this time, rubbing is performed so that the liquid crystal molecules are distributed approximately 9011 times between the upper and lower substrates 9 and 17. A TN-type liquid crystal display device is formed by placing polarizing plates 19 and 20 on the outside of this liquid crystal cell, aligning the polarization axis with the liquid crystal V white sK. →Figure 7 The capacitor circuit of the IJ type liquid crystal display device made as above is shown in Figure 8.

East Example 2 The manufacturing process is the same as in Example 1, but the oxide film formation process is different! In this case, the glass substrate 2 is placed as shown in Figure 9 (a) K.
After saturating the pixel electrode 22, the lead part, and the metal IF electrode 23 on one side of the MIM element, Ta is sputtered on the entire surface, and then thermal oxidation is performed in oxygen at 400 to 500 C to form an oxide film on the entire surface. Form 24.

Furthermore, the MIM device is completed by the same process as in Kll Example 1, and the appearance shown in FIG. 9(b) is obtained.

Although IIF was performed on the actual mackerel example above, the present invention is based on the above-mentioned example VctlF! For example, the substrate is not limited to Pyrex glass, but can be made of soda lime glass or any material used in ordinary liquid crystal display devices.

Method of Forming a Film: After forming a thin metal film, various oxidation methods such as anodic oxidation, thermal oxidation, plasma oxidation, or implantation of oxygen ions can be applied.

In addition, oxides and organic materials can be directly sputtered, OVD,
Various film forming techniques such as plasma CVN, single beam evaporation, induction heating evaporation, ion beam evaporation, and coating methods can be used.

Furthermore, regarding the zinc oxide thin film mentioned in the examples, any material can be used as long as it transmits W light under bright light and can be selectively etched for photoresist, insulation, and substrate materials. It is also possible to use inorganic materials such as , magnesium oxide, calcium oxide, and silicon 9ide, and organic materials such as polyimide resin.

According to Example 1, the tantalum that will become the lead part and one electrode 11 of the MIM element shown in FIG.
An oxide film was formed on the surface. Zinc oxide thin film Cr/^U thin film attached and MIM element type 1i! L f , Ni Cjr/
The width of the other electrode 150 of the V-type M element made of an Au thin film was set to 30 mm, and a matrix type liquid crystal display device was fabricated by combining it with a 300 sm square pixel wvIi.1. vth-tsvrm
e, Vsat = 2. When an OVrme liquid crystal was sealed and driven using a voltage averaging method of 115 by 1 and 1/512 duty, 12 to L5Vh-p
In the voltage range of 0N390- or more, OFF: 10 mo or less was obtained.

As explained above, according to the present invention, it is possible to obtain an MIM element with a minute area due to the self-line effect even if the photorin graph process has a pattern accuracy of several tens of microseconds. It is possible to correct the V-X polarity which has a polarity difference in the case of two M elements so that there is no polarity difference, and the life of the liquid crystal display device can be extended. Therefore, even if a large-scale matrices liquid crystal display with an even finer pattern becomes necessary in the future, there will be no need to use a high-nv manufacturer aligner, which will be advantageous in terms of manufacturing costs.

[Brief explanation of drawings]

Figure 1 shows the non-lsmI! It shows Ii property. FIG. 2 shows a circuit using a combination of an M element and a liquid crystal. Fig. 5 is a cross-sectional view and a sketch of a conventional MIM element. ◎ Fig. 4 is a plan view showing the same conventional MIM element and the arrangement of one pixel. FIG. 5 shows a glimpse of the manufacturing process of the MIM device according to the present invention. Sixth! llI is a plan view of one pixel of the liquid crystal display device according to the first embodiment of the present invention, and FIG. 7 is a sectional view of the liquid crystal display device. FIG. 8 is a circuit diagram of the matrix type liquid crystal display device of Example 1. FIG. 9 is a diagram illustrating the manufacturing process in Example 2. Above Yamaganjin Co., Ltd.

Claims (3)

[Claims] (1) It has a plurality of display pixels, and each of the display pixels is made of metal-in5ulator.
-Formation of a transparent conductive thin film on a transparent substrate in a matrix-type liquid crystal display mt combining non-t*m elements (hereinafter referred to as MIM elements) with a metal (abbreviated as MIM) structure, an xM element is formed on a transparent substrate. and buttering, formation of a metal thin film and buttering, formation of an insulating thin film, formation of a transparent thin film, formation of a positive photoresist layer, exposure from the back side of the transparent substrate, removal of the exposed photoresist portion, Removal of unnecessary parts of the transparent thin film, formation of metal thin film, removal of the transparent thin film remaining from the above-mentioned removal process 1 of the unnecessary part of transparent thin film, photoresist and metal thin film on its upper surface, and removal of the remaining second layer of metal thin film. This is a matrix-type liquid crystal display device that is characterized by being completed by Jung's work. (2) A matrix-type liquid crystal display device according to claim 1, characterized in that two MIM elements are connected to each pixel. (3) The matrix type liquid crystal display device according to claim 2, wherein two MIM elements are folded in series in opposite directions.