JPH012088A - Active matrix liquid crystal display device and its manufacturing method - 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 [Field of Commercial Use] The present invention relates to an active matrix liquid crystal display device having a field effect transistor formed on a thick film single crystal silicon substrate, and a method for manufacturing the same.

[Conventional technology]

In recent years, the application of twisted nematic type (TN type) t-centered liquid crystal display devices (1, CD) has been developed and has been used in the fields of wristwatches and calculators. In addition, matrix types, which can display arbitrary characters such as letters and figures by combining dots, are beginning to be used in information terminals, word processors, and the like. The structure of a matrix type LCD is such that two substrates having striped electrodes are arranged facing each other with a liquid crystal interposed therebetween so that the electrode lines on each substrate are perpendicular to each other. Such an LCD is driven by XY terminals called matrix terminals.

In order to expand the field of application of this matrix type LCD, it is necessary to increase the display MW. However, conventional LC
Since the voltage rejection rate change characteristic of D does not have a very steep rise, if the number of scans of the matrix terminal is increased in order to increase the display capacity, the effective The land saving ratio will decrease. For this reason, the viewing angle at which good contrast can be obtained becomes significantly narrower, so that in conventional LCDs, the maximum number of scanning lines was about 60 lines.

In order to significantly increase the display width of this matrix type LCD, an active matrix liquid crystal display device in which an active element for liquid crystal switching is arranged in each pixel of the LCD has been proposed.

In this active matrix liquid crystal display device, polycrystalline silicon is used as the semiconductor material for the active element because it is difficult to form single crystal silicon with good crystallinity on an insulator and from the viewpoint of light resistance. Did 1 =
' A thin film transistor (TPT) with a BT structure is used. Since it is difficult to manufacture an IC for driving an active element using polycrystalline silicon due to its crystallinity, a method of connecting an active element and a driving circuit with a terminal has been generally used for flat displays.

[Problem that the invention seeks to solve]

However, a 400x60011ki element display has 400 vertical and 640 horizontal terminals, requiring 1040 If connections and 1040 drivers, and the terminal connection technology has reached its limit. Hence the high density of the display.

Not only was it not possible to achieve high performance, but the connection process required additional costs.

An object of the present invention is to eliminate such conventional drawbacks and provide a high-yield, high-performance active matrix liquid crystal display device and a method for manufacturing the same.

[Means for resolving the issue]

In the active matrix liquid crystal display device of the present invention, an element substrate having an active element provided at a position determined by a data signal electrode and a scanning signal electrode and a counter substrate having a counter electrode are arranged to face each other with a liquid crystal interposed therebetween. In the active matrix liquid crystal display device, the element substrate has a device layer formed on the holding substrate via an adhesive 1-, and
In addition to the active element, at least a scanning side driving circuit and a data side driving circuit of the liquid crystal driving circuit are formed in the device layer, the active element is formed of polycrystalline silicon or amorphous silicon, and the liquid crystal driving circuit is formed of a single layer. It is made of crystalline silicon and has a structure in which data signal electrodes and scanning signal electrodes are formed on the opposite side of the device l-.

Further, in the method for manufacturing an active matrix liquid crystal display device of the present invention, an element substrate having an active element provided at a position determined by a data signal electrode and a scanning signal electrode and a counter substrate having a counter electrode are connected via a liquid crystal. In the manufacturing method of active matrix liquid crystal display devices arranged opposite to each other, the element substrate includes a step of forming an insulator on one main surface of a single crystal silicon substrate, and a step of forming an insulator on the base single crystal silicon of the insulator. a step of forming a contact hole until it reaches the contact hole; a step of forming polycrystalline silicon or amorphous silicon on the insulator to form an active element; a step of forming a wiring from the active element to the contact hole; a step of forming at least a scanning side drive circuit and a data side drive circuit of the liquid crystal drive circuits on one main surface of the single crystal silicon substrate on which the single crystal silicon substrate is not formed; a step of wiring the active element and the liquid crystal drive circuit;
a step of contacting one main surface side of the single crystal silicon substrate to a removing substrate with a layering agent and polishing from the t-m plane of the single crystal silicon substrate until the insulator is exposed; and the holding of the insulator. The device includes a circuit board for forming signal electrodes such as data signal electrodes and scanning signal electrodes on the surface opposite to the substrate, and for wiring to the active element through the signal electrodes and the contact holes.

〔Example〕

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

FIG. 1 is a cross-sectional view of a liquid crystal pixel section for explaining one embodiment of an active matrix liquid crystal display device of the present invention, and FIG. 2 is a schematic plan view of the element substrate shown in FIG. 1. .

As shown in FIGS. 1 and 2, this embodiment includes an element substrate having an active element 5 for switching liquid crystal pixels at a position determined by a data signal electrode 21 and a scanning signal electrode 20, and a counter electrode 14. The counter substrate 15 having the liquid crystal layer 1
3, which are arranged opposite to each other via
In the matrix liquid crystal display device 2, the element substrate has the device I- bonded to the holding substrate IK, and the device 1
Of the active element 5 and the liquid crystal drive circuit, a scan II drive circuit 22 and a data (iIll drive circuit 23) are formed in m, the active element 5 is formed of polycrystalline silicon or amorphous silicon, and the liquid crystal drive circuit is It is an active matrix liquid crystal display device made of single crystal silicon.

Furthermore, in this embodiment, the scanning side drive circuit 22 and the data side drive circuit 23 are formed using MOS transistors.

3 and 4 are representative conceptual circuit diagrams of such a scanning side drive circuit and a data 4A drive circuit, respectively.

As shown in FIG. 3, the scanning side drive circuit is configured to scan:! The number of shift registers 32 is equal to the number of 1-electrodes. A vertical synchronizing signal 26 is input to each of these shift registers 32, and its output signal is input to a driver 25 where it is adjusted to a voltage suitable for driving the liquid crystal and output as a scanning signal 27.

As shown in FIG. 4, the data-side instigator circuit has sample-and-hold circuits 28 only for the ridges of the data signal. Each of these sample and hold circuits 28 holds the video signal 29 by closing the gate in accordance with the horizontal synchronizing signal 30, and inputs this value into the driver 25 and outputs it as a data signal 31.

These circuits explained above are normal MO
As seen in S-IC, it is composed of MOS) transistors. Therefore, these circuits can be formed using the same process as that for forming MOS transistors for switching liquid crystal pixels.

Next, FIGS. 5A to 5C are cross-sectional views of element substrates arranged in the order of steps for explaining an embodiment of the method for manufacturing an active matrix liquid crystal display device according to the present invention.

First, as shown in FIG. 5(a), a silicon dioxide layer 3 with a thickness of 1 μm is formed on a single-crystal silicon substrate 4 at the required portions to expose the single crystal. A MOS 1C, which is a liquid crystal drive circuit 24, is formed in that portion. Thereafter, polycrystalline silicon is deposited on the silicon dioxide layer 3 to form a field effect transistor (FET) to form the active element 5.

The gate structure of this lI'ET is a single gate structure or a double gate structure, as shown in FIG. Note that the double gate structure is a structure in which two gates are arranged directly side by side, and corresponds to a circuit in which two PETs are arranged side by side. FIG. 5(a) shows such a circuit.

Next, as shown in FIG. 5(b), the surface on which the confectionery is to be formed is brought into contact with a holding substrate 1 made of quartz glass or the like through a contact layer 2 made of epoxy or polyimide. Next, the single crystal silicon substrate 4t excluding the device layer is removed by mechanical/chemical boring. In this case, borising uses an organic amine as the chemical solution, so silicon dioxide Im 3 F
i Not processed, polishing color silicon dioxide fB
It can be stopped at a depth of 3.

Next, as shown in FIG.
Formed with TO or the like.

The substrate thus formed is combined with a counter substrate 15 formed over the entire surface of the counter electrode 14 of ITO or the like shown in FIG. 1 via a spacer such as a glass fiber to form a liquid crystal cell. A normal epoxy organic seal is used for the seal. An active matrix liquid crystal display device is obtained by injecting liquid crystal into this cell to form a crystal-tolerant layer 13 and then sealing it.

Here, the confectionery substrate and the opposing substrate are subjected to alignment treatment by rubbing. In this case, an alignment film of polyimide or the like is often applied, but it is not essential, so it is omitted in FIG. In addition, the liquid crystal used was a commercially available TN type Sone crystal with a cell thickness of 8 μm, and the deflection plate was also a commercially available product. When an LCD using this TN type liquid crystal and this polarizing plate is statically driven, the viewing angle at which a contrast ratio CB of 5:1 can be obtained is ±50@.

With this confectionery configuration, 400x640 pixels, pitch 0.
An active matrix liquid crystal display device formed with a thickness of 0.05 mm exhibits almost the same display performance as when statically driven. Furthermore, if a signal equivalent to 2000 lines of scanning is applied as a simulated signal, almost the same display performance as in static driving can be obtained. For the drive signal of this display device, a signal similar to that used in a conventional active matrix liquid crystal display device in which M 08 ) transistors or 'f'FTs are stacked can be used. When a television screen containing halftones is displayed on this display device, the gradations are expressed very faithfully and the contrast is high, and contrast spots do not occur within the screen.

Since the panel according to this example has drive circuits laminated,
The number of terminals is significantly reduced from 1040 to 10, and the process of connecting the terminals is significantly simplified.

Moreover, since this panel is small, it is not only suitable for viewfinders in video cameras, but also can be applied to projection displays to obtain a good projection screen of 1 m x 1 m square, and also has good intermediate and A display. It is.

Next, an application example of the active matrix display device of the present invention will be described.

The embodiments described above can be used both as direct-view displays and as shadow-like projection displays. That is, in contrast to the direct view type, a projection type display, in which a liquid crystal panel is irradiated with strong light from a xenon lamp or the like and projected, is suitable for displaying a super large screen of about 1 m x 1 m square.

By combining the liquid crystal panel of a projection type display using a conventional laser thermal writing liquid crystal panel with the liquid crystal panel of the present invention, a laser and its instigator circuit are not required, so a small projection type display can be realized. .

Note that a conventional projection optical system can be used.

For example, as a liquid crystal panel, 400X6401!1ll
e. If the active matrix display device of the present invention with a pitch of 0.05 mm is used, the liquid crystal panel can be made considerably smaller, so that a reasonably compact projection optical system can be realized.

Furthermore, a normal overhead projector (so-called 011P) can also be used as the projection system.

Although the above embodiments and application examples have all been explained using monochrome screens, it is also possible to form color filters of 9 GB dots for each system on the opposing substrate, as is usually done. This makes it easy to change the color screen to I1.
You can get either a prone type or a projection type. Also,
In the case of a projection type, it is also possible to use three active matrix display devices according to the present invention, each of which is combined with one of the 8083 display devices, and then combine them to obtain a color screen.

〔Effect of the invention〕

As explained above, in the past, since the active element and its drive circuit were separate, it was necessary to connect the terminals, and it was not possible to obtain a stomach-like oily appearance of the wrinkle display. By fabricating this on the same substrate as each allotropic active element, it is possible to significantly reduce the number of terminals, and by applying it to a projection type, it is possible to obtain an ultra-small projection type display. . Historically, by fabricating the control circuit and the signal processing circuit on the same substrate, a television set or information terminal device can be constructed with only a small number of external passive components.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a quasi-crystalline pixel section for explaining one embodiment of the active matrix liquid crystal display device of the present invention, FIG. 2 is a schematic plan view of the element substrate shown in FIG. 1, and FIG. and FIG. 4 are conceptual circuit diagrams of the scanning side drive circuit and data 1ltlI drive circuit shown in FIG. 2, respectively, and FIGS. 5(a) to (C) are the active matrix liquid crystal display of the present invention. FIG. 2 is a cross-sectional view of an element substrate arranged in the order of steps for explaining a method for manufacturing the device. 1...Transparent substrate, 2...No adhesive, 3
...Silicon dioxide layer, 4...Single crystal silicon substrate, 5...Mactip element, 6...
...Silicon dioxide, 7...Stock holding Kiei, 8
...Contact hole, 9...Signal image,
10...Drain region, 11...Source region, 12...Gate electrode, 13...
・Liquid crystal layer, 14... Opposite, 15...
・Counter substrate, 16...Drain electric storage, 17...
...Source electrode, 18...lff1I accumulation electrode, 19...Data signal electrode, 2o...
・Scanning signal electrode, 21... Data signal electrode, 2
2... Set meal 11I11 drive circuit, 23...
・・Data 1klIIIJA moving circuit, 24・・・・・°
Liquid crystal drive circuit, 25...driver, 26...
... Vertical synchronization signal, 27 ... Scanning signal, 28
...Sample and hold circuit, 29...
Video signal, 30...Horizontal synchronization signal, 31...
...Data signal.゛(Figure 1 Figure 2 Figure 3 Figure 4 Figure S

Claims (2)

[Claims] (1) In an active matrix liquid crystal display device in which an element substrate having an active element provided at a position determined by a data signal electrode and a scanning signal electrode and a counter substrate having a counter electrode are arranged to face each other with a liquid crystal interposed therebetween. , in the element substrate, a device layer is formed on a holding substrate via an adhesive layer; in addition to the active element, at least a scanning side driving circuit and a data side driving circuit of the liquid crystal driving circuit are formed on the device layer; The active element is formed of polycrystalline silicon or amorphous silicon, the liquid crystal drive circuit is formed of single crystal silicon, and data signal electrodes and scanning signal electrodes are formed on the opposite side of the device layer. Features an active matrix liquid crystal display device. (2) An active matrix liquid crystal display device in which an element substrate having an active element at a position determined by a data signal electrode and a scanning signal electrode and a counter substrate having a counter electrode are arranged to face each other with a liquid crystal interposed therebetween. In the manufacturing method, the element substrate includes a step of forming an insulator on one main surface of a single crystal silicon substrate, a step of forming a contact hole in the insulator until it reaches the underlying single crystal silicon, and a step of forming a contact hole on the insulator. a step of forming an active element by forming polycrystalline silicon or amorphous silicon; a step of forming a wiring from the active element to the contact hole; A process of forming at least a scanning side drive circuit and a data side drive circuit of the liquid crystal drive circuit, a process of wiring the active element and the liquid crystal drive circuit, and holding one main surface side of the single crystal silicon substrate with an adhesive. polishing the single crystal silicon substrate from the back side until the insulator bonded to the substrate is exposed; and forming signal electrodes of data signal electrodes and scanning signal electrodes on the surface of the insulator opposite to the holding substrate. A method of manufacturing an active matrix liquid crystal display device, comprising the step of wiring the active element through the signal electrode and the contact hole.