JPH0567209B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an active matrix liquid crystal display device and a method for manufacturing the same, and particularly to a device in which active elements such as field effect transistors and pixel electrodes are arranged in a grid pattern and driven. The present invention relates to an active matrix liquid crystal display device that uses a liquid crystal layer to display images, and a method for manufacturing the same.

[Conventional technology]

In the past, the application of liquid crystal display devices centered on twisted nematic type (TN type) has been developed and is used in large quantities in wristwatches, calculators, etc., but matrix type liquid crystal display devices, which can display arbitrary characters such as characters and figures, have developed. Liquid crystal display devices are also beginning to be used. This matrix liquid crystal display device is a liquid crystal display device in which two substrates having striped electrodes are arranged facing each other with a liquid crystal interposed therebetween.

Recently, active matrix liquid crystal display devices have been proposed in which active elements are arranged in series in each pixel of the liquid crystal display device in order to significantly increase the display capacity of the matrix liquid crystal display device. In this active matrix liquid crystal display device, data signal electrodes and scanning signal electrodes formed on a substrate are formed to cross each other perpendicularly. Regarding such active matrices, please refer to the journal ``Proceedings of SID'', Vol. 24, No. 2.
``Promise and Challenge of Thin Film Silicon Approaches to Active Matrix''
Thin−FilmSilicon Approaches to Active
Matrices).

Furthermore, recently, transferred semiconductor devices using polysiling have appeared as active devices. For details on this transferred semiconductor element and its manufacturing method, please refer to the ``Proceedings of the 45th Autumn 1981 Academic Conference of the Japanese Society of Applied Physics'' (lecture number 12a-c-2) and the ``Japanese Journal of the Japanese Society of Applied Physics''. of
Applied Physics), Volume 23, Page L815 (published in 1984).

[Problem that the invention seeks to solve]

Although the TN type liquid crystal display device can increase the contrast, there is a problem in that the display range of characters, figures, etc. is limited.

In addition, it is essential for normal matrix liquid crystal display devices to increase the display capacity, but the voltage transmittance change characteristic, which is one of the display characteristics, does not have a very steep rise, so in order to increase the display capacity, it is necessary to increase the display capacity. When the number of drive scans is increased,
The execution voltage applied to each of the selected pixel and the non-selected pixel is reduced. Therefore, there is a problem that the viewing angle for obtaining good contrast in a matrix liquid crystal display device becomes extremely narrow, and the number of scanning lines is also limited to about 100 lines.

Furthermore, in active matrix liquid crystal display devices, there are still various problems with active elements formed on insulating substrates. In other words, this active element is an FET that uses amorphous silicon (a-Si) or polycrystalline silicon (p-Si) as a semiconductor material.
Most of them are thin film transistors (TFTs) with a structure, or TFTs with an FET structure using single crystal silicon (s-Si) as a semiconductor material. Among these, the manufacturing process for the former a-Si and p-Si TFTs has not yet been established, so the yield is low, the on/off current characteristics of good products are insufficient, and the number of scans is limited. Furthermore, since the on/off current characteristics are not uniform even within a single substrate, not only it is not possible to produce halftones like a television screen, but also the contrast becomes weak and contrast spots occur within the screen. On the other hand, since the latter s-Si TFT can be obtained by using the conventional silicon IC process as is, the yield is good, the characteristics of good products are sufficient, and there is no practical limit to the number of scans.
Since Si is opaque, it has the disadvantage that it is difficult to produce all colors.

Furthermore, the above-mentioned a-Si and p-Si can be used as active elements.
In addition to the method using Si, single crystal silicon is epitaxially grown on a crystalline insulator such as sapphire or spinel, and an element (this element is formed on sapphire) is formed on the epitaxial layer.
There is also a method of forming an SOS (SOS). this
SOS can achieve performance comparable to elements on s-Si, but
The drawback is that the cost of substrates such as sapphire is very high and that large-area substrates cannot be obtained.

Furthermore, even when the latest transferred semiconductor elements are used as active elements in active matrix liquid crystal display devices, they do not operate stably under intense light irradiation, such as under direct sunlight or inside a projection optical system. The problem is that it is difficult to do.

In short, in such a conventional active matrix liquid crystal display device, data signal electrodes and scanning signal electrodes formed on a substrate are formed on the same plane so as to cross each other perpendicularly, and TFTs are used as active elements. In some cases, both of these electrodes are formed on the same surface of the element substrate via some kind of insulating thin film. As a result, pinholes in the insulator thin film and dielectric breakdown can cause disconnections due to steps at the shoot and intersection between the two electrodes, leading to lower manufacturing yields and unstable operation under intense light irradiation. There's a problem.

A first object of the present invention is to provide an active matrix liquid crystal display device that has high performance and prevents short-circuiting and disconnection of data signal electrodes and scanning signal electrodes, and a method for manufacturing the same.

A second object of the present invention is to provide an active matrix liquid crystal display device and a method for manufacturing the same that achieves a high manufacturing yield.

Furthermore, a third object of the present invention is to provide an active matrix liquid crystal display device that can realize stable operation under intense light irradiation, and a method for manufacturing the same.

[Means for solving problems]

In the active matrix liquid crystal display device of the present invention, an element substrate on which active elements and pixel electrodes are formed at the intersections of data signal electrodes and scanning signal electrodes, and a counter substrate having electrodes opposite to both the electrodes are arranged as liquid crystal layers. In the active matrix liquid crystal display device, the element substrate is formed by bonding a device layer in which active elements are formed on a single crystal silicon region separated by an insulator region to a holding member, and The scanning signal electrode or the data signal electrode is formed on the side on which the active element is formed, and the light shielding layer is formed on the side opposite to the side on which the active element is formed so as to block incident light to the active element. , the pixel electrode connected to the active element through the contact hole provided in the insulator region, and the data signal electrode or the scanning signal electrode are respectively formed to correspond to each other.

Further, the method for manufacturing an active matrix liquid crystal display device of the present invention includes an element substrate forming an active element and a pixel electrode at a position where a data signal electrode and a scanning signal electrode intersect; A method for manufacturing an active matrix liquid crystal display device in which a substrate is formed through a liquid crystal layer includes a step of forming an insulator region on one main surface of a single crystal silicon substrate, and etching the insulator region to etch the monocrystalline silicon substrate. forming a single crystal silicon region on a crystalline silicon substrate; forming a contact hole in the insulator region until reaching the single crystal silicon substrate; and forming an active element on the single crystal silicon region. , a step of forming an electrode wiring from the active element to the contact hole, and a step of forming the scanning signal electrode or the data signal electrode connected to the active element on substantially the same surface as the active element. , bonding one main surface side of the single crystal silicon substrate to a holding member via an adhesive layer, and polishing the single crystal silicon substrate from the side opposite to the one main surface until the insulator region is exposed. a light shielding layer that blocks incident light to the active element in the insulator region on the polished surface, and wiring to the active element formed on the one main surface through the contact hole. forming the pixel electrode and the data signal electrode or the scanning signal electrode in correspondence with each other, and forming the element substrate and the counter substrate on which the active element, the light shielding layer, and various electrodes are formed, thereby forming the liquid crystal display. The method includes a step of sealing the layer.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

1 and 2 are sectional views of main parts for explaining a first embodiment of an active matrix liquid crystal display device of the present invention, respectively, and FIG. 3 is an element in the first embodiment of the present invention. 2 is a schematic plan view showing a substrate along line A-A' showing the cross-sectional position in FIG. 1 and line B-B' showing the cross-sectional position in FIG. 2; FIG.

As shown in FIG. 1, in this embodiment showing a cross section of a data signal electrode and a pixel electrode (cross section taken along line A-A' in FIG. 3), an active matrix liquid crystal display device includes active elements such as MOS transistors. It is formed by sandwiching a liquid crystal layer 6 between an element substrate 3 having a device layer 1 including a device layer 1 attached to a holding member 2 and a counter substrate 5 having a counter electrode 4, and is particularly constructed by arranging the active elements in a matrix. Ru. The device layer 1 described above has a gate insulating film 9 on the upper surface of a single crystal silicon region 8 separated by an insulator region 7.
After covering the gate electrode 10 with an interlayer insulating film 11 over the gate electrode 10, a drain region 12 and a source region 13 are formed by ion implantation or the like. A drain electrode 15 and a source electrode 16 connecting the contact hole 14 and the drain region 12 and source region 13, and a transparent single layer are formed on the surface of the single crystal silicon region 8 opposite to the surface on which the source and drain regions are formed. A light shielding layer 26 that blocks incident light to the active element through the crystalline silicon region 8, and a pixel electrode 18 and a data signal electrode 19 formed to be connected to the source electrode 16 and drain electrode 15, respectively. and is attached to the holding member 2 by an adhesive layer 17.

Next, as shown in FIG. 2, in this embodiment, a cross section of a pixel electrode, a data signal electrode, and a scanning signal electrode formed on the opposite side with an insulator region in between. (B- in Figure 3
B′ cross section), the above device layer 1 is an insulator region 7
A scanning signal electrode 2 which also serves as a gate electrode is provided on one side of the
0 is deposited, and the pixel electrode 18 and data signal electrode 19 described in FIG. 1 are deposited on the opposite side. The other points are similar to those explained in FIG. Form by sandwiching 6.

Next, as shown in FIG. 3, the cross section taken along the line A-A' (FIG. 1) and the cross section taken along the line B-B' (FIG. 2) are as described above. The element substrate 3 in this first embodiment has a data signal electrode 19 connected to a source electrode and a scanning signal electrode 20 which also serves as a gate electrode arranged in a matrix, and a pixel electrode 18 is connected to the drain electrode. Data signal electrode 1
9 and the scanning signal electrode 20 are each connected to a matrix terminal 21 which is an X-Y terminal of the liquid crystal display device for external connection, and a MOS transistor 22 is formed at the point where they intersect. In addition,
In order to simplify the explanation, two data signal electrodes 19 and two scanning signal electrodes 20 have been described here, but normally, the same electrodes are arranged above, below, left and right, and in between.

FIG. 4 is a schematic plan view of an element substrate for explaining a second embodiment of the active matrix liquid crystal display device of the present invention.

As shown in FIG. 4, a data side drive circuit 23 and a scan side drive circuit 24 are connected to the matrix terminals.
This is the same as the description of the first embodiment described above in FIG. 3, except that the MOS transistor 22 connected to the pixel electrode 18 is provided in a predetermined single crystal silicon region at the same time as the MOS transistor 22 connected to the pixel electrode 18. In this case, the data side drive circuit 23 is composed of a shift register and a sample holder, and the scanning side drive circuit 24 is composed of a shift register, so that the data side drive circuit 23 is composed of a shift register and a sample holder.
This is the same circuit.

Since the panel according to the second embodiment has drive circuits laminated, the number of terminals is significantly reduced from 1040 to 10, and the process of connecting the terminals is extremely simplified.
Since this panel is small, it is suitable for viewfinders such as video cameras. Furthermore, if applied to a projection type display, a good projection screen of 1 m x 1 m square can be obtained, and the halftone display is also good.

Next, FIGS. 5a to 5c are cross-sectional views of the main parts of the element substrate shown in the order of steps for explaining one embodiment of the method of manufacturing an active matrix liquid crystal display device of the present invention.

As shown in FIG. 5a, a single crystal silicon substrate 2
A silicon oxide film (SiO ₂ ) having a thickness of 2 μm is formed on the substrate 5 by thermal oxidation, and the silicon oxide film in the portion corresponding to each display pixel is removed by reactive ion etching. This remaining portion of the silicon oxide film becomes the insulator region 7. In the exposed portion of the single crystal silicon substrate 25 due to the etching,
Silicon is selectively epitaxially grown using a SiH ₂ Cl ₂ -H ₂ -HCl system to the same height as the insulator region 7 to form a single crystal silicon region 8. A FET type transistor is formed in this single crystal silicon region 8 by a method similar to a normal MOS process. Regarding selective epitaxial growth, here, selective epitaxial growth was performed by selectively removing the silicon oxide film after thermal oxidation, but if the single crystal silicon substrate 25 is selectively oxidized, selective epitaxial growth is not performed. Good too. In that case, a step difference occurs between the single crystal silicon region and the insulator region, but substantially the same performance can be obtained.

Next, as shown in FIG. 5b, a gate insulating film 9 made of a silicon oxide film is formed on the single crystal silicon region 8, and a polycrystalline silicon layer or a metal layer such as aluminum, molybdenum, tungsten, etc. A gate electrode 10 is formed. Next, after forming an interlayer insulating film 11 made of a silicon oxide film, a drain region 12 and a source region 13 are formed by ion implantation. Next, two contact holes 14 per pixel are formed in the insulator region 7 made of a silicon oxide film by photolithography, and chromium, molybdenum, tungsten, etc. are deposited by metal vapor deposition to form a drain electrode 15 and a source electrode 16, respectively. Form. As a result, the drain electrode 15 of the MOS transistor, which is an active element,
Wiring is provided from the source electrode 16 to the contact hole 14. Note that, as described above, the gate electrode 10 also serves as a scanning signal electrode. Further, at this stage, the single crystal silicon substrate 25 under the device layer remains without being separated.

Next, as shown in FIG. 5c, the MOS
The element forming surface is covered with an adhesive layer 17 made of an insulating polymer material, such as epoxy or polyimide resin.
It is bonded to a holding member 2 made of quartz glass, borosilicate glass, pyrex glass, soda glass, silicon wafer, or the like. After that, MOS
Single crystal silicon substrate 2 excluding transistor forming part
5 is removed by mechanochemical polysyring. In this case, polishing uses an organic amine as a chemical solution, and since silicon oxide, which is a component of the insulator region 7, has a much slower processing speed than single-crystal silicon, the polishing process is carried out to the depths of the insulator region 7. You can stop it. In this manner, the device layer 1 having the insulator region 7 and the single crystal silicon region 8 in which elements are formed can be easily left. Furthermore, a data signal electrode 19 is formed on the polished surface of the insulator region 7 and is electrically connected to the source electrode 16 through the contact hole 14 . This data signal electrode 19 is the same metal electrode as the drain electrode, source electrode, etc. Further, a pixel electrode 18 is formed on the same surface as the polished surface, and is electrically connected to the drain electrode 16 through the contact hole 14. This pixel electrode 18
is a transparent electrode made of indium-tin, tin oxide, or the like. In this way, the pixel electrode 18 is formed on the surface of the element substrate, and the data signal electrode 19 and the scanning signal electrode 20 are formed on both sides of the device layer 1.

Next, a light shielding layer 26 is formed on the surface of the single crystal silicon region 8 opposite to the surface on which the MOS transistor is formed.
is formed to cover the channel portion of the transistor. Examples of the light shielding layer 26 include a metal film or a multilayer film with a metal compound, and a polymer film containing dye. The metal film includes chromium, molybdenum, tungsten, aluminum,
There are vapor deposited films such as nickel, and the multilayer films include chromium oxide, chromium, chromium oxide, and the like.
Furthermore, the polymer membrane contains gelatin, casein,
In addition, any material can be used as long as it has a light shielding effect. This light shielding layer 26 can prevent the MOS transistor from malfunctioning even under intense light irradiation.

On the other hand, although not shown in FIG. 5c, another contact hole is made in the insulator region 7, and as shown in FIG. 19
Matrix terminals 21 are provided on the surface of the element substrate 3 so as to be electrically connected to the scanning signal electrodes 20 and 20, respectively.

Note that silicon oxide is formed as an intermediate layer by sputtering on the device layer 1 including the above-mentioned insulator region 7 and single crystal silicon region 8, and a metal layer such as chromium is patterned thereon to form a light shielding layer 26. It is also possible to do this.

By going through each process described above, the MOS transistor 22, which is an active element, the pixel electrode 18, the data signal electrode 19, and the scanning signal electrode 20 are placed on the holding member 2 as shown in FIGS. 1 and 3.
Each lead electrode and matrix terminal 21 are formed to complete the element substrate 3.

The element substrate 3 thus formed is formed into a liquid crystal cell with a thickness of about 8 μm by interposing spacers such as glass fibers on a counter substrate 5 on which a counter electrode 4 made of indium-tin oxide or the like is formed on the entire surface. . A liquid crystal layer 6 is formed by injecting liquid crystal into this liquid crystal cell. Finally, an active matrix liquid crystal display device is obtained by sealing this liquid crystal layer 6 using an epoxy organic seal. In addition,
In this liquid crystal display device, a TN type liquid crystal was used as the liquid crystal, and a commercially available polarizing plate was used as the counter substrate. When this liquid crystal display device is statically driven, the viewing angle at which a contrast ratio of 5:1 can be obtained is ± It is 50°.

In one embodiment of the method for manufacturing the active matrix liquid crystal display device described above, the number of vertical and horizontal pixels is
I made a prototype with 400 x 640 pixels and a pitch interval of 0.2 mm,
The overall display performance is almost the same as when static driving is performed, and in particular, even when a signal equivalent to 2000 scans is applied as a simulated signal, almost the same display performance as when static driving is obtained. In addition, the drive signal is similar to the drive signal used in active matrix liquid crystal display devices stacked with conventional MOS transistors or TFTs, and when displaying a TV screen that includes halftones, it is not possible to faithfully express gray scales. , a high-contrast screen can be obtained, and contrast spots do not occur within the screen. Furthermore, according to this method of manufacturing a liquid crystal display device, a-Si or p-Si
The yield is also significantly improved compared to those using TFT.

The embodiments of the present invention have been described above, and the active elements in each embodiment include not only MOS transistors but also other field effect transistors, bipolar transistors, various diodes,
The present invention can also be carried out using combinations thereof.

Furthermore, in the element substrate of the above embodiment, the scanning signal electrodes are formed on the holding member side of the device layer, and the data signal electrodes are formed on the opposite side, but these may be formed in the opposite direction, and similar methods may be used. Display performance can be obtained.

Finally, application examples of the present invention will be explained.

Each of the embodiments described above is a direct-view type liquid crystal display device, but on the other hand, for an ultra-large screen liquid crystal display of about 1 m x 1 m square, the liquid crystal panel is irradiated with strong light from a xenon lamp. There is a projection type liquid crystal display device that projects images. In a projection type liquid crystal display device using such a conventional laser thermal writing liquid crystal panel, the liquid crystal panel can be replaced with the active liquid crystal panel of the present invention.
By replacing the liquid crystal panel of a matrix liquid crystal display device, miniaturization can be achieved because a laser and its driving circuit are not required. A conventional projection engineering system can be used. for example,
As a liquid crystal panel, 400 x 640 pixels, pitch 0.05mm
If a liquid crystal display device is used, the size can be significantly reduced. Note that a normal overhead projector (so-called OHP) can also be used as the projection system.

In addition, although the screen in the above application example was a black and white screen, by forming a color filter of RGB dots corresponding to each pixel on the opposing substrate, a display device that has a color screen for both direct view type and projection type. can be obtained. Also, especially in the case of projection type,
It is also possible to obtain a color screen by using three active matrix liquid crystal display devices of the present invention, each of which is combined with one of the three RGB display devices, and then synthesized.

〔Effect of the invention〕

As explained above, in the past, a-Si was used on a transparent substrate.
Alternatively, p-Si is formed and TFT is formed on it, which has poor characteristics and the number of scan lines is limited to 500, which is equivalent to static drive.However, according to the present invention, firstly, data signal electrodes and scan Since the signal electrodes do not intersect with each other on the same plane of the substrate, electrode disconnections due to shorts and steps between the electrodes can be eliminated, and line defects in display can be significantly reduced. Also,
Second, since active elements can be formed on the single-crystal silicon region that serves as a transparent substrate, good characteristics can be obtained, and large-capacity scanning of about 2,000 lines is possible, which has a significant effect on improving manufacturing yield.

Furthermore, thirdly, the active elements can be stably operated even under intense light irradiation, which has the effect of improving the reliability of the liquid crystal device.

Further, by combining a large number of liquid crystal display devices according to the present invention, it is possible to increase the area, and by manufacturing the peripheral drive circuit on the same substrate as the active element of each pixel, there is an effect that the number of terminals can be significantly reduced. Furthermore,
Application to a projection type liquid crystal display device also has the effect of making it ultra-small.

[Brief explanation of drawings]

1 and 2 are sectional views of main parts for explaining a first embodiment of an active matrix liquid crystal display device of the present invention, respectively, and FIG. 3 is an element in the first embodiment of the present invention. 4 is a schematic plan view showing the board along line A-A' showing the cross-sectional position in FIG. 1 and line B-B' showing the cross-sectional position in FIG. 2;
The figure is a schematic plan view of an element substrate for explaining a second embodiment of the active matrix liquid crystal display device of the present invention, and FIGS. FIG. 3 is a cross-sectional view of the main parts of the element substrate shown in the order of steps for explaining one embodiment. DESCRIPTION OF SYMBOLS 1... Device layer, 2... Holding member, 3... Element substrate, 4... Counter electrode, 5... Counter substrate, 6...
...Liquid crystal layer, 7...Insulator region, 8...Single crystal silicon region, 9...Gate insulating film, 10...Gate electrode, 11...Interlayer insulating film, 12...Drain region, 13...Source region , 14... Contact hole, 15... Drain electrode, 16... Source electrode, 17... Adhesive layer, 18... Pixel electrode, 19...
...Data signal electrode, 20...Scanning signal electrode, 21
... Matrix terminal, 22 ... MOS transistor, 23 ... Data side drive circuit, 24 ... Scanning side drive circuit, 25 ... Single crystal silicon substrate, 26 ...
...Light shielding layer.

Claims (1)

[Scope of Claims] 1. An element substrate on which an active element and a pixel electrode are formed at a position where a data signal electrode and a scanning signal electrode intersect, and a counter substrate having an electrode facing both said electrodes are formed with a liquid crystal layer interposed therebetween. In the active matrix liquid crystal display device, the element substrate is formed by bonding a device layer in which active elements are formed in single crystal silicon regions separated by an insulator region to a holding member, and the scanning signal electrode or the data signal electrode on the side on which the active element is formed; a light shielding layer formed on the side opposite to the side on which the active element is formed so as to block incident light to the active element; and the insulator. An active matrix liquid crystal display device characterized in that the pixel electrode connected to the active element through a contact hole provided in a region and the data signal electrode or the scanning signal electrode are respectively formed in correspondence with each other. 2. Active matrix liquid crystal in which an element substrate forming an active element and a pixel electrode at a position where a data signal electrode and a scanning signal electrode intersect, and a counter substrate having an electrode opposite to both electrodes are formed with a liquid crystal layer interposed therebetween. A method for manufacturing a display device, comprising: forming an insulator region on one main surface of a single-crystal silicon substrate; etching the insulator region to form a single-crystal silicon region on the single-crystal silicon substrate; forming a contact hole in the insulator region up to the single crystal silicon substrate; forming an active element on the single crystal silicon region; and forming an electrode wiring from the active element to the contact hole. forming the scanning signal electrode or the data signal electrode connected to the active element on substantially the same surface as the active element; and forming an adhesive layer on one main surface side of the single crystal silicon substrate. a step of polishing the single crystal silicon substrate from the side opposite to the one principal surface until the insulator region is exposed; a light shielding layer that blocks incident light to the active element, the pixel electrode that is wired to the active element formed on the one main surface through the contact hole, and the data signal electrode or scanning signal electrode. and a step of sealing the liquid crystal layer with the element substrate on which the active element, the light shielding layer, and various electrodes are formed, and the counter substrate.・
A method for manufacturing a matrix liquid crystal display device.