JPS599635A - electro-optical device - 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 an electro-optical device using liquid crystal.

More specifically, the present invention relates to an electro-optical device which combines a liquid crystal display device with a non-linear element to improve display characteristics.

In recent years, the application of liquid crystal display devices 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 as display devices for small electronic devices in addition to wristwatches and calculators. became.

In order to further expand the field of application of this liquid crystal display device, it is necessary to increase the display capacity, but in conventional TN type liquid crystal display devices, the rise of voltage-contrast characteristics is not very steep, so it is necessary to increase the number of multiplex orders. The difference between the effective voltages applied to the non-selected point, the cow selected point, and the selected point becomes small, resulting in crosstalk, which limits the ability to drive multiple digits. One way to avoid these drawbacks is to use an IJ type device that combines non-linear elements or switching elements with a liquid crystal display device, as well as TPT and IJ type devices that use amorphous silicon, polysilicon, or compound capacitors. diode.

Various studies have been made, including the use of varistors made of zinc oxide or the like.

Among such non-+1iiJ type elements, JP-A-52-14
9090 & metal-insulator-metal (getal-, 4nsu, 1ator-peta
A non-linear element (hereinafter referred to as MIM) having a structure (abbreviated as MIM)
Since the device configuration is simple, the device has the advantage that the manufacturing process is shorter and the device design is easier than other nonlinear devices.

It is thought that current flows in this M element due to the tunnel effect, Schottky effect, Poole-Frenkel effect, etc., and as shown in Figure 1, there is no electricity! It shows a typical voltage-current characteristic.

Insulators include Al, Ta, Nb,
Oxides such as Ti, Si, MO, W, and Hf, oxides of the metals doped with nitrogen, inorganic materials such as chalcogenide glass, and even organic materials such as polyimide resin can be used.

+jfJ If the self-insulating film is sandwiched with a metal, an M structure will be obtained, and this metal may be ljJ He metal, N1, Or, Au, or their alloys, or 5
n02. ■”203 eTo(engine n 20, +Sn
O.

) or an extremely thin transparent conductive thin film made of metal such as Or or Au can be used.

When a voltage is applied to an M-type IA element, the conduction mechanism differs depending on the thickness G of the absolute M film, and we believe that the tunnel effect is dominant at 50 to 100X, and the Schottky effect and Poole-Frenkle effect are dominant at ioo to 100X. There is. In the combination of a liquid crystal display device and an M element, which is the object of the present invention, it is considered desirable to use a region exhibiting the Poole-Frengal effect in view of the liquid crystal driving method, and in that region, the voltage -' current The characteristics are determined by the Poole-Frenggal formula (%) (1) When a liquid crystal display device incorporating this M element is driven using the voltage averaging method used to drive a normal matrix type liquid crystal display device, the M Due to the non-linearity of the M element, the 0N10FF effective value ratio applied to the liquid crystal becomes larger than the 0N10FF effective value ratio of the voltage averaging method itself, making it possible to drive a matrix with more digits. When the M element is combined with a liquid crystal display device, the equivalent circuit for one pixel is the second
As shown in the figure, the capacitance 01JIM and the nonlinear resistance RMI
M element 1 in parallel with M, and it! (:!L
It can be considered that the liquid crystal part 2 in which + and the external RLO are connected in series.

A pressure of '1u is applied to both ends of this, but the effective voltage actually applied to the liquid crystal section 2 is determined by the time constant of the M element 1, the time constant of the liquid crystal section 2, and the capacity of the MIM element 1.
Ratio between MIM and OLO, which is the capacity of liquid crystal part 2, a x, o
/ OM I y, the time saving number of liquid crystal part 2 and the value of OL
When the time constant of the motor M*element 1 is at an appropriate value, the effective pressure becomes the largest. Naturally, the greater the nonlinearity of the M element 1, the greater the number of digits of matrix drive.

Here, to explain the MIM of the conventional M process M element, for example, as shown in Figs. After forming and patterning the metal thin film 5 into a desired shape, an insulator thin film 6 is formed on the surface. Further, a thin metal M is applied and patterned to form the counter electrode 7 of the MIM element. At this time M
The area of the M element is the area where the metal electrode 5 and the counter electrode 7 overlap each other. To create a liquid crystal display device, next, pixel electrodes 8 are formed using a transparent conductive thin film, a liquid crystal alignment layer is formed on the surface, a counter substrate is formed with a constant gap maintained, and a cell is formed, and liquid crystal is sealed in the gap. Then paste the polarizing plate and
It is an N liquid irises display device.

When trying to make a matrix type liquid crystal display device using M elements with such a structure, conventional matrix type liquid crystal display devices often use pixel dimensions of 0.3 to 0.5 mm pitch. M process M that matches the pixel size like this
The dimensions of the element are 3 to 6 μm square. In the current photoringraph technology, this dimension region of 6 to 6 μγn angle is the boundary region between LSI and VI'3, and since it is a matrix type display device M, the display part size is as large as 5 to 10 cm. It is necessary to form elements having dimensions in the submicron region over a fairly large area, which involves considerable difficulty in soldering. Furthermore, if a matrix type liquid crystal display device having pixels of a very small size is to be manufactured, VLSI technology must be used completely, which is not desirable in terms of cost.

In the present invention, by devising a new manufacturing method of M element, the minimum dimension is 10 μm &! It is possible to manufacture an M element with a small area by using the photorin graph culm of W, and to lower the manufacturing cost by lowering the grade of the necessary exposure equipment.

Hereinafter, the present invention will be explained using a practical example.

Example 1 Pyrex, 1000-5000X on glass substrate 9
It is formed by tantalum fan 10f varnish battering and patterned into a predetermined shape.

Next, the anode was acclimatized in a citric acid water bath, and the tantalum thin film was
An oxide film 11 is formed on the exposed surface [FIG. 5(a)].

Next(ko, IT O(I it 2Os +S n O2
, ) m IN 12 formed on the entire surface of the base, a temporary negative photoresist 16 is applied and a blebake is performed. Then, exposure is performed from the back side of the Pyrex glass substrate 9 [fifth
Figure (b)]. After development, the result is as shown in FIG. 5(C), and after boost baking, the TO# film 12 is etched and the resist 13 is removed, as shown in FIG. 5(d). Furthermore, the shape of the required pixel 14 is modified using the TOIJJi film (12).
If the tantalum thin film 10 is etched, the oxide film 11 on the surface of the tantalum thin film 10 and the pixel electrode 14 will become M
The construction of MJr# is completed and looks like the one shown in Figure 6.

The length of the M element is determined by the length of the tapered part of the insulating film 11 and the width of the pixel' electrode 14.

The surface of the Pyrex glass substrate 9 on which the M elements and pixel electrodes 14 are formed is coated with polyimide (ηl resin), fired, and rubbed with a cotton cloth to perform a liquid crystal alignment treatment. Separately, striped transparent electrodes 16 are formed. Then, prepare a Pyrex glass counter substrate 17 that has been subjected to liquid crystal alignment treatment by rubbing with polyimide resin, and
The liquid crystal 18 is sealed while maintaining the gap. At this time, rubbing is performed so that the liquid crystal molecules are twisted approximately 90 degrees between the upper and lower groups &9117. Polarized light is applied to the outside of this liquid crystal cell.
The polarizing plates 19 and 20 are arranged according to the alignment state of the liquid crystal, forming a TN type liquid crystal display device. →Figure 7 The equivalent circuit of the electro-optical device made through the above steps is shown in Figure 8.

Example 2 The manufacturing process is the same as in Example 1, but when exposing from the back side, light is incident obliquely as shown in FIG. 9 (α). Then, the negative resist 13 is exposed to light with directionality, and by development, it takes on the shape shown in FIG. 9(b).
Process after etching and resist removal
The shape of 12 is the...i + mi shape of Figure 9 (C), the 10th shape
The figure shows the flat shape. That is, the tantalum lead parts 10 and 10' which are adjacent in the left-right direction in FIG. 10 and the ITO thin INs 12 and 12' which become pixel electrodes are electrically separated. Therefore, the pixel 14 as shown in FIG.
When forming 14' by photo-etching, it is sufficient to simply separate 12' into the upper F direction, and as shown in FIG. By etching 12, the M element and the pixel'
Electrode 14 is formed. Thereafter, the electro-optical device is manufactured in the same manner as in Example 1.

As explained above, in the conventional M process and M element manufacturing process, photoetching had to be carried out with an accuracy of several micrometers in width, whereas with the method of the present invention, photoetching must be performed with an accuracy of several tens of micrometers.
It is only necessary to perform photoetching of a certain degree, and it is possible to form the M element and the pixel 'α pole without using a high-precision mask aligner, and it is possible to reduce the Nnn soot F in the photoetching process.

[Brief explanation of drawings]

FIG. 1 shows the nonlinear characteristics of Mg alloy. FIG. 2 shows an equivalent circuit when an MIM element and a liquid crystal are combined. FIG. 6 is a cross section rmr and a sketch of a conventional M element. FIG. 4 is a plan view showing the arrangement of the same conventional M element and one pixel. FIG. 5 is an explanatory diagram of the manufacturing process of the M element of the present invention. FIG. 6 is a diagram of a pixel portion of a liquid crystal display device according to the first embodiment, and FIG. 7 is a cross-sectional view of the liquid crystal display device. FIG. 8 is an equivalent circuit of the matrix type liquid crystal display device of Example 1. Figures 91Δ to 12 are manufacturing steps in Example 2! X
fr: Diagram for explanation. (0) , 'S9 Figure 11 To I

Claims (1)

[Claims] 1. An electro-optical device having a plurality of display pixels and a non-linear element coupled to each of the display pixels, wherein the non-linear element has a metal-insulating film-transparent conductive film structure and is transparent. A blood optical device iM characterized in that it is manufactured by a process that includes a self-alignment process from the back side of the substrate onto the substrate. 2. The blood-air optical device described in item 1 of Patent No. 11-1, characterized in that in the self-alignment step from the back surface of the substrate, the substrate G is exposed from an oblique direction.