JPH05249496A - Substrate for liquid crystal display and its production - Google Patents

Abstract

PURPOSE:To obtain TN system or the like having high contrast even in a structure using a single crystal semiconductor thin film. CONSTITUTION:This liquid crystal display substrate is used for an active matrix liquid crystal display, comprising a plastic transparent plate 30 and a single crystal silicon film 10 having a hole 18 to transmit light on the rear surface of the plate 30. On the single crystal silicon film 10, MOB transistor alpha is formed as one structural component of the liquid crystal driving circuit. A metal film 50 as a light shielding layer is formed between the MOS transistor alpha and the plastic transparent plate 30 to cover the MOS transistor alpha.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display substrate used in an active matrix type liquid crystal display and a manufacturing method thereof.

[0002]

2. Description of the Related Art With the arrival of the advanced information age, flattening is strongly desired for video information display. Among the various types of flat displays, the liquid crystal display is also a promising candidate because it also has the excellent aspect of lightweight and low power consumption. In particular, the active matrix liquid crystal display is a CRT (Cathodrd Ray
It is attracting attention because it has an image quality comparable to that of Tube).

FIG. 4 shows a typical equivalent circuit of a conventional active matrix type liquid crystal display. In the figure, 60 is a scanning signal wiring electrode, 61 is a data signal wiring electrode, and 63 is a MOS transistor. Reference numeral 64 in the figure denotes a liquid crystal sealed between the transparent electrode terminal 65 and the counter electrode terminal 66. The output voltage of the scan signal drive circuit 68 is applied to the gate of the MOS transistor 63 through the scan signal wiring electrode 60, whereby the conduction state of the MOS transistor 63 is controlled. The output voltage of the data side drive circuit 67 is applied to the transparent electrode terminal 65 through the channel of the data signal wiring electrode 61 and the MOS transistor 63, and the liquid crystal 64 is polarized and oriented to drive the liquid crystal cell.

Among the active matrix systems, the MOS transistor type active matrix system in which a glass substrate is used for one substrate of the liquid crystal cell and single crystal silicon is used for the other substrate, and a MOS transistor array is formed on the substrate, a conventional LSI is used. There is an advantage that the manufacturing technology can be used as it is and a high-performance element can be easily manufactured.
Furthermore, it is easy to integrate and integrate the peripheral drive circuit on the same substrate of the MOS transistor array, and there are advantages that the lead connection between the drive circuit unit and the display unit is simplified, the device is downsized, and the reliability is high. .. That is, the MOS transistor type active matrix system is most suitable for downsizing, high reliability, and cost reduction of the peripheral circuit section of the liquid crystal display.

[0005]

However, as long as single crystal silicon is used, since it is opaque in the visible light region, it is not possible to use a TN method or the like with good contrast, and the image quality of the liquid crystal display is poor. There is an inherent drawback. Further, as a result of having to use the reflection type method, there is a drawback that it is difficult to use in a dark place and the field of use is limited. In particular, it is a big problem for application to home televisions.

The present invention was created in view of the above background, and provides a liquid crystal display substrate and a manufacturing method thereof which can adopt a TN method or the like with good contrast even though it has a structure using single crystal silicon. To provide.

[0007]

A liquid crystal display substrate of the present invention is a liquid crystal display substrate used in an active matrix type liquid crystal display, and a transparent substrate which is one of the substrates of a liquid crystal cell and a transparent substrate. A single crystal semiconductor thin film formed on the surface of the substrate and having a plurality of light-transmitting holes; a plurality of elements which are at least one component of the liquid crystal drive circuit and are formed on the single crystal semiconductor thin film; And a light shielding layer for covering.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partial sectional view of an active matrix type liquid crystal display substrate, and FIG. 2 is a diagram showing a manufacturing process of the liquid crystal display substrate.

The liquid crystal display substrate described by way of example is used for a MOS transistor type active matrix liquid crystal display. The sectional view shown in FIG. 1 shows a portion corresponding to one pixel of a liquid crystal display.

Reference numeral 30 in the drawing denotes a plastic transparent plate as a transparent substrate, which corresponds to one substrate of the liquid crystal cell. In addition,
The other glass substrate of the liquid crystal cell is not shown.

A single crystal silicon film 10 as a single crystal semiconductor thin film is provided on the surface of the plastic transparent plate 30 (the lower surface in the figure).
Are formed. A transparent hole 18 is provided on the surface (the lower surface in the figure) of the single crystal silicon film 10. This translucent hole 18
The transparent electrode 22 of the liquid crystal cell is formed in the portion. The other transparent electrode and liquid crystal in the liquid crystal cell are not shown.

A MOS transistor α is formed on the single crystal silicon film 10. The MOS transistor α is one component of the liquid crystal drive circuit, and is adapted to drive the liquid crystal cell. The SIO ₂ films 11, 15, 17 and the wiring electrodes 12, 13,
It is composed of 14 mag.

Single crystal silicon film 10 and plastic transparent plate
An insulating film 42, a metal film 50, and an adhesive layer 41 are provided in this order with respect to 30. The metal film 50 is a MOS transistor α
Covers the upper side in the figure and serves as a light shielding layer. That is, the light entering from the plastic transparent plate 30 is shielded to prevent it from hitting the MOS transistor α.

However, since FIG. 1 shows only a portion corresponding to one pixel, the other transparent holes 18, the MOS transistor α, and the metal film 50 are not shown, but the number of pixels of the liquid crystal display is not shown. There are as many as.

Next, a method of manufacturing the liquid crystal display substrate having the above structure will be described with reference to FIG.

First, the surface of a P-type single crystal silicon wafer 1 as a single crystal semiconductor wafer is thermally oxidized to SIO ₂
Create a membrane. Then, the SIO ₂ film in the drain and source portions of the MOS transistor α is removed by a selective etching technique such as photo etching or reactive ion etching to form the SIO ₂ film 11 having a predetermined pattern (FIG. 2 (a)). ).

After that, a predetermined n-type diffusion layer is formed in the drain and source portions by a thermal diffusion method or an ion implantation method. Then, the SIO ₂ film 11 that will become the gate
Is removed by a selective etching technique, and a SIO ₂ film 17 having a predetermined pattern is formed by thermal oxidation at about 1000 degrees. Subsequently, a metal film of AL, MO or the like is formed on the surface of the substrate by sputtering or electron beam evaporation or the like, and the wiring electrode 13 (gate line) having a predetermined pattern is formed by the photo etching technique or the selective etching technique. After that, CVD or plasma CV
The SIO ₂ film 15 having a predetermined pattern is formed by the D method or the like (
Figure 2 (b)).

Next, after opening the electrode windows of the drain portion and the source portion by the photo etching technique and the selective etching technique, the AL, again by the sputtering or the electron beam vapor deposition, etc.
A metal film such as MO is formed, and the wiring electrodes 12 and 14 (source line, drain line) having a predetermined pattern are formed by a photo etching technique and a selective etching technique. This produces the MOS transistor α. Furthermore, CVD method and plasma CVD
The insulating film 42 of SiN or the like is formed by the method. Subsequently, a metal film such as AL or MO is formed on the surface of the substrate by sputtering or electron beam evaporation, and a metal film 50 having a predetermined pattern is formed by the photo etching technique and the selective etching technique (Fig. 2).
(c)).

After that, an adhesive material (adhesive layer 41) such as epoxy is applied on the surface of the insulating film 42 and the like, the metal film 50 is sandwiched and the plastic transparent plate 30 is attached and adhered (FIG. 2 (d)). ..

Then, the single crystal silicon wafer 1 is smoothed and thinned to a predetermined thickness from the back surface side of the single crystal silicon wafer 1 by grounding, lapping, polishing or the like. Then, even in the single crystal silicon wafer 1, MO
Unnecessary portions other than the S transistor α and the like are removed. As a result, the single crystal silicon film 10 having the light transmitting hole 18 is formed (FIG. 2 (e)).

Next, SIO _{2 is formed} by the selective etching technique.
The films 11 and 15, and if necessary, the insulating film 42 and the adhesive 41 are sequentially cut into a predetermined pattern, after being cut off, an ITO (Indium Tin Oxide) film or the like is formed on the entire surface of the substrate by sputtering or electron beam evaporation. When the transparent electrode 22 having a predetermined pattern is formed by the photo-etching technique and the selective etching technique and the transparent electrode 22 and the wiring electrode 14 are connected, the desired transmissive active matrix type liquid crystal display of the present invention as shown in FIG. 1 is obtained. A substrate is created (Fig. 2 (e)).

In the case of the first embodiment, in addition to the merits described later, since an inexpensive and light plastic transparent plate is used as the transparent substrate, there is an advantage in reducing the cost and weight of the liquid crystal display. ..

Next, the second embodiment will be described. FIG. 3 is a diagram showing a part of the manufacturing process of the liquid crystal display substrate. Since FIG. 3D corresponds to FIG. 1 used in the description of the first embodiment, the structure of the liquid crystal display substrate will be described with reference to this drawing. However, the same components as those in the first embodiment are designated by the same reference numerals.

In the figure, 30 'is a glass substrate as a transparent substrate. A single crystal silicon film 10 having a light transmitting hole 18 is formed on the surface of the glass substrate 30 '. In the figure, 43 is an insulating film such as SiN, and a transparent electrode 22 is formed on the surface of the transparent hole 18 and above the wiring electrode 14 which will be described later on this surface. The other transparent electrode and liquid crystal in the liquid crystal cell are not shown.

A MOS transistor α is formed on the single crystal silicon film 10. MOS transistor α is SIO
It is composed of _two films 11, 15, 17 and wiring electrodes 12, 13, 14 and the like. The wiring electrode 14 of the MOS transistor α is electrically connected to the transparent electrode 22 through a hole formed in a part of the insulating film 43.

A metal film 50 'is provided between the MOS transistor α and the insulating film 43. MOS transistor α
The upper side surface of the metal film 50 'is covered with the metal film 50'.
Serves as a light shielding layer of the MOS transistor α when driving the liquid crystal. That is, the light entering from the other transparent substrate (the transparent substrate facing the glass substrate 30 ') in the liquid crystal cell is M
Prevents hitting the OS transistor α.

The glass substrate 30 'and the single crystal silicon film
Provided between 10 and 10 is an adhesive layer 41 ′ made of polyimide, epoxy or the like.

Next, a method of manufacturing the liquid crystal display substrate having the above structure will be described with reference to FIG.

Since the manufacturing process shown in FIG. 2B in the first embodiment is the same, the manufacturing process thereafter will be described. From the state shown in FIG. 2 (b), after opening the drain and source electrode windows in the MOS transistor α by photo-etching technology and selective etching technology, AL by sputtering or electron beam evaporation,
A metal film such as MO is formed, and the source / drain wiring electrodes 12 and 14 are formed by a photo etching technique and a selective etching technique. This produces the MOS transistor α.
Similarly, a metal film 50 'is formed (FIG. 3 (a)).

Then, a wax 44 is applied to the surface of the single crystal silicon wafer 1 in the figure as an adhesive for temporary fixing. The supporting substrate 31 made of glass or the like is temporarily fixed with the wax 44 so that the metal film 50 ′ is sandwiched on the upper side of the single crystal silicon wafer 1 in the figure.

In this state, the single crystal silicon wafer 1 is smoothed and thinned to a predetermined thickness by grounding, lapping, polishing or the like from the back surface side of the single crystal silicon wafer 1 to form the single crystal silicon film 10. (Fig. 3
(b)).

On the other hand, an adhesive (adhesive layer 41 ') such as polyimide or epoxy is applied to the surface of the glass substrate 30', and the surface of the glass substrate 30 'is adhered to the back surface of the single crystal silicon film 10 and then a predetermined The wax 44 is melted under temperature conditions and the supporting substrate 31 is removed (FIG. 3 (c)).

Next, the SIO ₂ films 15 and 11 and the single crystal silicon film 1 are formed by the photo etching technique and the selective etching technique.
0, unnecessary portions of the adhesive layer 41 'are removed to form a predetermined pattern. At this time, the single crystal silicon film 10
A transparent hole 18 is formed in the. After that, spatter or low temperature C
An insulating film such as SiN is formed on the substrate surface by the VD method,
The insulating film 43 is formed by the photo etching technique and the selective etching technique. At this time, a hole for connecting the transparent electrode 22 and the wiring electrode 14 is also formed.

Subsequently, an ITO (Indium Tin Oxide) film or the like is formed on the surface of the substrate by sputtering or electron beam vapor deposition and the like, and is subjected to photo-etching technology and selective etching technology.
A transparent electrode 22 is formed on the transparent hole 18 and on the periphery of the hole. At this time, the transparent electrode 22 and the wiring electrode 14 are connected
(Fig. 3 (d)).

A liquid crystal display substrate is manufactured through the series of processes described above. Even in the case of the second embodiment, the same effect as that of the first embodiment can be obtained as the light shielding layer.
In addition, since the metal film 50 ′ serving as the light shielding layer is formed at the same time when the source / drain wiring electrodes 12 and 14 are formed, the number of steps can be reduced and the steps can be simplified. Furthermore, since the SIO ₂ films 11, 15 and the like are etched from the element surface side of the single crystal silicon substrate 10, there is also an advantage that alignment during photo-etching becomes easy.

The present invention is not limited to the first and second embodiments described above, but other substrates such as quartz can be used for the transparent substrate, and other single crystal semiconductors such as GaAs can be used for the single crystal semiconductor thin film. Can be used. Further, a MOS transistor and a capacitor element for charge storage may be formed on the single crystal semiconductor thin film, or a CMOS, a diode element, a bipolar element, or the like may be formed, and a peripheral circuit including a liquid crystal drive circuit is formed. May be taken.

[0037]

As described above, according to the liquid crystal display substrate and the method of manufacturing the same of the present invention, the following advantages can be obtained. First, since the single crystal semiconductor thin film is provided with the light-transmitting holes, a transmissive liquid crystal display can be obtained, and a TN method or the like with good contrast can be used. Therefore, it becomes possible to brighten the screen of the liquid crystal display and improve the image quality by using a backlight or the like. In particular, the application to a home television or the like becomes easy. Further, since the light shielding layer is provided, the plurality of elements can operate stably without being affected by light, and the liquid crystal display has good electrical characteristics. Furthermore, since other peripheral circuits, a control circuit in a television, and the like can be easily incorporated in the single crystal semiconductor thin film, there is an advantage in reducing the assembly cost and downsizing.

[Brief description of drawings]

FIG. 1 is a diagram for explaining a first embodiment of the present invention, which is a partial cross-sectional view of a liquid crystal display substrate.

FIG. 2 is a diagram for explaining the manufacturing method of the liquid crystal display substrate in the first embodiment, which is a diagram illustrating a manufacturing process.

FIG. 3 is a diagram for explaining the second embodiment and is a diagram showing a manufacturing process.

FIG. 4 is a diagram showing a typical equivalent circuit of a conventional active matrix liquid crystal display.

[Explanation of symbols]

 1 Single crystal silicon wafer 10 Single crystal silicon film 18 Translucent hole α MOS transistor 30 Plastic transparent plate 31 Support substrate 41 Adhesive layer 44 Wax 30 'Glass substrate 50, 50' Metal film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Shuhei Tsuchimoto 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (4)

[Claims] 1. A liquid crystal display substrate used for an active matrix liquid crystal display, comprising a transparent substrate which is one substrate of a liquid crystal cell, and a plurality of light transmitting holes formed on the surface of the transparent substrate. A single crystal semiconductor thin film, a plurality of elements that are at least one component of a liquid crystal drive circuit and are formed on the single crystal semiconductor thin film, and a light shielding layer that covers the plurality of elements. A liquid crystal display substrate characterized by the following. 2. A liquid crystal drive circuit other than a plurality of elements is formed on the single crystal semiconductor thin film.
The liquid crystal display substrate described. 3. A plurality of devices are formed on a single crystal semiconductor wafer, a light shielding layer is formed, a transparent substrate is adhered with the light shielding layer sandwiched therebetween, and unnecessary portions of the single crystal semiconductor wafer are removed. The method for manufacturing a liquid crystal display substrate according to claim 1, wherein a single crystal semiconductor thin film having a plurality of light transmitting holes is formed by setting a predetermined thickness. 4. A plurality of devices are formed on a single crystal semiconductor wafer, a light shielding layer is further formed, and then a supporting substrate is temporarily fixed with an adhesive layer sandwiching the light shielding layer. In this state, the single crystal semiconductor wafer is formed. A transparent hole is formed by removing the unnecessary portion of the single crystal semiconductor thin film after removing the supporting substrate after forming the single crystal semiconductor thin film to a predetermined thickness by cutting the back surface of the single crystal semiconductor thin film. Item 2. A method for manufacturing a liquid crystal display substrate according to item 1.