JPS58181023A - Manufacture of electrooptic device - Google Patents

Abstract

PURPOSE:To make a display using an MIM large-sized, by anodizing the surface of the first metal which is etched selectively, forming the second metallic film, etching the second metallic film so as to be laid across the first metallic film, and removing the second metallic film. CONSTITUTION:A Ta film 12 is formed (a) on a glass transparent substrate 11, and Ta is etched and is patterned (b) to a prescribed shape. In this way, a data line 13 and one electrode 14 of an MIM element are formed at the same time. A Ta oxide film 15 is formed by being anodized in a citric acid solution, and a part of the Ta wire 13 is also anodized (c). A Cr film 16 is formed and its etching is executed (d). A resist film 17 is formed and a resist on the Ta electrode 14 is removed (e). A Cr film 18 is removed (f) by etching. In this way, the MIM element utilizing the Ta film thickness is formed. Subsequently, a transparent electrode 19 is formed in a prescribed shape, by which an MIM substrate is manufactured (g). In this way, an element having a size of 1/100 of a conventional one is obtained.

Description

[Detailed description of the invention] The present invention relates to a method for manufacturing an electro-optical device.

More specifically, we manufacture electro-optical devices using liquid crystals that display by accumulating and retaining charge in each pixel electrode using a nonlinear element (hereinafter referred to as an MIM element) having a metal-oxide film-metal structure. Regarding the method.

In recent years, liquid crystal display devices have been put into practical use and are being applied to many fields including wristwatches and calculators.

However, when considering applications in other fields, such as display units in information terminals and small personal electronic devices, despite the advantages of display units such as small volume, low voltage drive, and low power consumption, However, the driving voltage-contrast characteristics were not very good, and since multi-digit IJ matrix driving was not possible, there were problems in that only a few information devices could be used for display.

Matrix driving using M elements has been considered as one way to overcome the drawbacks of this liquid crystal display device.

This method uses an M element 1 in which a nonlinear resistor RMIM and a capacitor CMIM are connected in parallel, and a liquid crystal in which a resistor RLa and a capacitor QLC are connected in parallel, as shown in Figure 1, which shows the equivalent circuit for one pixel. It can be considered that the capacitor 2 is connected in series with the capacitor 2, which has the liquid crystal as the dielectric, and the low resistance state of the MIM element 1 is utilized during the matrix drive selection period to accumulate charge in the capacitor 2, which has the liquid crystal as the dielectric. During the non-selection period, the high resistance state of the MIM element 1 is utilized to hold the above-mentioned charge, thereby applying an electric field to the liquid crystal to control the alignment state of the liquid crystal to perform display.

In the case of this method, the nonlinearity of the M element 1, the capacitance QLa value and the resistance Hr of the capacitor 2 using the liquid crystal as a dielectric,
The effective value applied to the liquid crystal is determined by the correlation of the three o values. Of these three, capacitor 2 uses liquid crystal as a dielectric.
The values of the capacitance QLO and the resistance RLC are determined by determining the dimensions of the pixel electrode, the cell gap, and the liquid crystal used. Therefore, the M element 1 is required to have characteristics according to the liquid crystal part. For example, a cell with a 7 μm gap and a 04 m square pixel electrode has a dielectric anisotropy of Δ6-27 (ε
=35. g=8), Vt&:LIVrma.

Enclose a nematic liquid crystal with Vaat=t5Vrms,
If you want to drive a twisted nematic cell with a duty of 1/500, for example, T, -Ta2α-N
The dimensions required for the M element of sOr/A u #I structure are approximately 5 μm square.

The M element is formed by the following method. Ta Ill 6 is formed on a transparent substrate 5F made of glass or the like by sputter deposition or the like, and Ta is selectively etched using a 7-otoetching method to form a predetermined shape. At this time, the 'ra wiring and one electrode of the MUM are formed simultaneously.

C1.01wt% of the buttered Ta6
After polar oxidation in an aqueous citric acid solution, Cr (NsOy
Alternatively, Au may be continuously deposited as an upper layer) (8) and patterned into a predetermined shape by photo-etching to form an M element. 7...
・Sun! #Oxide film. After that, a transparent electrode 9 is formed to serve as one electrode substrate of the liquid crystal display device.

Thereafter, it is assembled into a liquid crystal display device in the same manner as a normal display device.

The minimum limit for the size of the M element, ie, the force, is determined by the accuracy of the 7-dimensional etching, especially the accuracy of the photolithography. A high-precision mask aligner is required for 5μm dimension <turning, but such a high-precision mask aligner has a small substrate size, and currently works best on a 4-inch diameter substrate, and for larger substrates. Mask aligners that use substrates have lower resolution. There is a method using an electrical device called a pattern generator, which is used in mask production. This pattern generator has a resolution of 2 to 3 .mu.m and is capable of producing a substrate with a size of 6 inches square, but its processing capacity is small and the processing capacity is about one sheet per hour, making it expensive and unsuitable for mass production.

SUMMARY OF THE INVENTION An object of the present invention is to provide a large-sized electro-optical device by eliminating such drawbacks, easing restrictions on pattern dimensions of photolithography in pattern formation, and facilitating manufacturing on large-sized substrates.

In the present invention, the dimensions of the element, which were conventionally limited only by the precision of photoetching, are limited by the thickness of the metal film, thereby significantly reducing the dimensions and forming picture elements with smaller dimensions than in the past. This allows display devices to become larger and have higher resolution.

The following will be explained according to examples.

Example 1 This will be explained using FIGS. 4 and 5. FIGS. 4 and 5 are a cross-sectional view and a plan view of the present invention, respectively.

T a is deposited on a transparent substrate 11 such as glass by sputter deposition.
To form the film 12 (a), selectively etch 'ra' by photo-etching method and pattern T(+) into a predetermined shape (b). At this time, the wiring !1 (data line) 1
3 and one electrode 14 of the M element are formed at the same time.

Next, a Ta# film 15 is formed on the surface of the Tat electrode 14 by polar oxidation in a 0.01 wt% citric acid aqueous solution. At this time, a part of the Tα layer 1113 is also anodized (c).

Next, a Cr film 16 is formed by thermal evaporation or the like, and etched into a predetermined shape (d). At this time, CrMi on the Ta electrode 14 is removed. First, a resist film 17 is formed according to a normal photoetching process, and a Ta electrode 511 is formed.
The resist on 14 is removed by normal photolithography technique (#). 'ra electrode 14 exposed O
The r film 18 is removed by etching (1). As a result, an MIM element utilizing the Ta film thickness is formed.

After this, a transparent electrode 19 is formed in a predetermined shape to form an MIM substrate (?). A display device is obtained by assembling the display device in the same manner as a normal liquid crystal display device.

Example 2 This will be explained using FIG.

FIG. 6 is a sectional view illustrating the present invention.

After forming the Cr film 16 and patterning it into a predetermined shape in the same manner as in Example 1 (al), a resist 21 with low viscosity is applied to the entire surface (6).

Because the viscosity is low, the resist film thickness is thick in the recesses on the substrate.
The convex portion becomes thinner. This tendency is further exacerbated by heat treatment after resist coating. The resist-coated substrate is subjected to plasma etching or ion etching to expose the resist surface (c). What is exposed is the Crm above T, which is the highest surface (the resist film thickness is the thinnest). When this exposed Or is etched, the stepped portion of TaFIk is not etched because it is thick in the vertical direction and remains as shown in FIG. 6, forming the electrode 22 of the M I Ml element. Thereafter, a transparent electrode 19 is formed to produce an M-process M-element substrate (U). Thereafter, a display device is obtained by assembling in the same manner as a normal liquid crystal display device.

The dimensions of the M element manufactured by the above method are as follows.

If the resolution of the mask aligner is 20 μm, the conventional MIM element dimensions are Tαα electrode width 2×4 according to the invention.
If the TQ film thickness is 02 μm, the Ta electrode width (Ta film thickness)
0. 2 /j m X Cr electrode width 20An=4
μ-, which makes it possible to reduce the M element size by 1/100 of the conventional size. The drawings in this explanation have the same shape as the conventional shape, so the M-type M elements are formed on both sides of the Ta electrode, so the total dimensions of the two M-type elements are 8 μ-, which is 1/50. It becomes. One M as shown in Figure 7
It is easy to use IM.

In the description of the present invention, Cr was used as the second metal, but O
In addition to r, NiCr is commonly used, and Au is sometimes formed on top of the metal to facilitate connection with the transparent electrode and as a metal passivation film for the liquid crystal.

Further, the transparent electrode may be formed before forming the Ta film or before forming the Cr film.

As described above, according to the present invention, compared to the conventional M process M element area, the area is 1 to 2
It becomes possible to obtain an M element with an order of magnitude smaller size.

[Brief explanation of the drawing]

FIG. 1 shows an equivalent circuit of a MUM element for one pixel and a liquid crystal section. FIGS. 2 and 3 show conventional M-engine and M-elements. Figures 4(a) to 5(a) to 5(a) are cross-sectional views and plane circles showing the MIM device according to the present invention. FIG. 7 is a cross-sectional view showing the M-engine M element. FIG. 7 is a plan view showing the M-engine M element according to the present invention. 'j J figure-1/1 (J) No. 50 Fig. 6 Fig. 7 121-

Claims (1)

[Claims] a step of forming a first metal film on a substrate; a step of selectively etching the first metal into a predetermined shape; a step of anodizing the surface of the first metal; a step of selectively etching the second metal film into a predetermined shape so that a portion of the second metal straddles the first metal covered with the oxide film; selectively removing the second metal film on the first metal film in the metal film pattern.