JPH11282013A - TFT array for liquid crystal display device, method of manufacturing the same, liquid crystal display device using the same, and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [Problem] To manufacture a large area liquid crystal display device,
An object of the present invention is to provide a TFT array in which an active layer is a polysilicon film having a uniform field effect mobility in an in-plane direction, and a liquid crystal display device using the same. SOLUTION: After a buffer layer 2, a polysilicon layer 4, a gate insulating layer 5, and a gate electrode 6 are sequentially formed on a glass substrate 1, impurities are implanted to form a source region 10 and a drain region 9. When the polysilicon layer 4 is formed, silicon, which is an evaporation sample, is evaporated using a pressure gradient plasma gun, and then the evaporated silicon particles are irradiated onto the glass substrate 1 while being excited in the plasma region. A silicon layer is formed. Since the ionized particles with high energy were used, the migration was high, and a polysilicon thin film which could be used as it was in a pixel switch transistor as it was deposited was obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, a thin film transistor used as a control element of the liquid crystal display device, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, active matrix type liquid crystal display devices have been developed. Among them, a thin film transistor (polysilicon layer) having a high field effect mobility of electrons is used instead of an amorphous silicon layer as an active layer. Developments to improve display characteristics by shortening the switching time of TFTs have been actively conducted.

[0003] A conventional method of manufacturing a polysilicon layer (which will later become an active layer), which is currently regarded as the most promising, will be described below with reference to the drawings. Hereinafter, a method for manufacturing a low-temperature polysilicon layer that can be manufactured at a relatively low temperature (approximately 600 ° C. or less) that can use an inexpensive glass substrate instead of an expensive quartz substrate will be described as an example. .

FIG. 4 is a cross-sectional view showing a manufacturing process of a conventional thin film transistor. In FIG. 4, reference numeral 1 denotes a glass substrate (here, an inexpensive glass substrate which is not usable at a high temperature is used as an example, but a quartz substrate may be used), 2 denotes a buffer layer formed on the substrate, and 3 denotes an amorphous substrate. A silicon layer, 4 is a polysilicon layer, 5 is a gate insulating layer, 6 is a gate electrode, 7 is a source region, 8 is a drain region, 9 is a contact hole, 10 is a source electrode, and 11 is a drain electrode.

Next, the manufacturing process of a conventional thin film transistor using a low-temperature polysilicon layer will be specifically described with reference to FIG.

First, a buffer layer 2 is formed on a glass substrate 1.
Silicon with a thickness of, for example, 600 _ThreeN_FourForming this
Amorphous silicon layer 3 over buffer layer 2
accumulate. And in this state, the amorphous silicon layer
3 was irradiated with excimer laser
The recon layer is locally heated and melted and finally polycrystallized,
A polysilicon layer is formed (FIG. 4A).

Next, on the polysilicon layer 4 formed by irradiation of excimer laser light or infrared light, for example,
A gate insulating layer 5 made of Si ₃ N ₄ having a thickness of 00 and SiO _{2 having} a thickness of 1500 is formed. Then, a gate electrode 6 made of, for example, Mo of 6000 is formed on the gate insulating layer 5, and phosphorus ions are implanted into the polysilicon layer 4 using the gate electrode 6 as a mask (FIG. 4B).

[0008] Thereafter, the polysilicon layer 4 is irradiated again by excimer laser light in the step of FIG.
Activating the phosphorus ions implanted into the source region 1
0 and the drain region 9 are formed (FIG. 4C).

Finally, the gate insulating layer 5 is etched to form a contact hole 9 reaching the source region 7 and the drain region 8, and 3000 are formed in the contact hole 9.
When the source electrode 10 and the drain electrode 11 are formed by embedding Al having a film thickness of 10 nm, a low-temperature polysilicon thin film transistor is completed.

[0010]

However, in the above-mentioned conventional method of manufacturing a polycrystalline silicon thin film transistor, there is a problem that display unevenness occurs when displaying on a liquid crystal display device. So in the following,
The cause of such a problem will be described with reference to FIG.

FIG. 5 (a) shows the T.V. of a general liquid crystal display device.
FIG. 1 is a plan view schematically showing a substrate on which an FT array is formed. In FIG.
Is a TF for a pixel switch formed on the glass substrate 12.
A pixel portion on which a T array element is formed, 14 is a gate drive circuit portion having a built-in TFT, and 15 is a source drive circuit portion having a built-in TFT.

The thin film transistor formed by the process as shown in FIG. 4 is the same as the pixel unit 13, the gate drive circuit unit 14, and the source drive circuit unit 1 shown in FIG.
5 respectively. Therefore, when the amorphous silicon is polycrystallized by excimer laser annealing in the step shown in FIG. 4A, an excimer laser beam must be applied to almost the entire surface of the glass substrate 12 in FIG. 5A. . When excimer laser light is applied to amorphous silicon formed in such a large area, it is usually indispensable to scan with linear excimer laser light (line beam).

As described above, the polysilicon layer formed by forming an excimer laser beam into a linear beam (line beam) and scanning the large-area amorphous silicon layer has an in-plane field effect mobility. Is uneven. This is because, when silicon melted by excimer laser irradiation recrystallizes, polycrystallization is performed in a state where the nucleus of crystallization cannot be specified, and amorphous silicon formed on the glass substrate This is because silicon cannot be polycrystallized at the same time. The non-uniformity of the field-effect mobility eventually causes display unevenness (for example, linear unevenness) in the liquid crystal display device.

Actually, when an amorphous silicon layer having a large area such as 320 mm.times.400 mm is scanned and irradiated with an excimer laser beam as a line beam, the field effect mobility becomes 50 to 300 c.
variation in the range of m ² / Vsec, for example, in a pixel portion are formed of a TFT array, a field-effect mobility than polysilicon around towards the center portion of the polysilicon in the peripheral region becomes higher tendency .

As described above, in the conventional method of manufacturing a low-temperature polycrystalline silicon thin film transistor, when forming a large-area liquid crystal display device, the field effect mobility of polysilicon after polycrystallization is not uniform. (Particularly, a pixel portion in which TFTs are formed in an array is remarkable), and it is difficult to obtain a liquid crystal display device without display unevenness.

In view of the above problems, the present invention provides a TFT for a liquid crystal display device in which an active layer is made of polysilicon having uniform field effect mobility in an in-plane direction when manufacturing a large area liquid crystal display device. It is a main object to provide an array and a method for manufacturing the same, and a liquid crystal display device using the same and a method for manufacturing the same.

[0017]

In order to achieve the above object, a first aspect of the present invention is to provide at least a transparent pixel electrode group and a pixel switch TFT group formed on a transparent substrate and a connection between them. The source bus line, the gate bus line, and the driving circuit connected thereto, and the field effect movement of the pixel switch TFT group is 1 to 25 cm.
² / V · s, and the field effect movement of the TFT or MOS transistor group constituting the drive circuit is 100 cm ² /
V.s or higher, TF for liquid crystal display device
Provide a T-array.

According to this structure, the pixel switching TFT
Since the field effect movement of the array is set to a relatively low value of 1 to 25 cm ² / V · s, the field effect mobility in the plane of the thin film transistor for a pixel switch which needs to form a thin film transistor over a large area is reduced. It is possible to maintain uniformity.

According to a second aspect of the present invention, there is provided at least a first comb-shaped transparent pixel electrode group formed on a transparent substrate and a pixel switch TFT group having a field effect movement of 1 to 25 cm ² / V · s. A driving circuit composed of a source bus line and a gate bus line connected to them, and a TFT or MOS transistor group connected to them and having a field effect movement of 100 cm ² / V · s or more, and the first comb-shaped pixel electrode A TFT array for an IPS-type liquid crystal display device, characterized by including a second comb-shaped electrode opposed to the TFT array.

According to this structure, the pixel switching TFT
Since the field effect movement of the group is set to a relatively low value of 1 to 25 cm ² / V · s, the field effect mobility in the plane of the thin film transistor for the pixel switch which needs to form the thin film transistor over a large area is reduced. It is possible to maintain uniformity. Further, by adding a pixel switch TFT group and a driving circuit composed of a TFT or MOS transistor group having a field effect movement of 100 cm ² / V · s or more connected via a source bus line and a gate bus line. Thus, a TFT array that can be driven at a high frequency can be obtained.

In the first and second inventions, when an n-channel TFT is used in the array as a TFT for a pixel switch, a TFT for a liquid crystal display device capable of high-speed response with a field effect transfer of 5 to 25 cm ² / V · s. An array is obtained.

According to a third aspect of the present invention, there is provided at least a step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material using a pressure gradient plasma gun on a transparent substrate; Forming a source / drain region by diffusing p or n-type impurities; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film Forming a group of pixel switching TFTs by forming a source electrode and a source bus line, forming a group of transparent pixel electrodes, and attaching and connecting an IC chip in which a driving circuit is formed in advance. A method for manufacturing a TFT array for a liquid crystal display device, characterized by providing:

According to this method, a TFT array having a pixel switch TFT group having a uniform in-plane field effect mobility and a pixel switch TFT of 1 to 25 cm ² / V · s can be obtained without using a laser annealing method. .

A fourth aspect of the present invention is a method for forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material using a pressure gradient plasma gun on a transparent substrate, and forming a driving circuit. A step of selectively heating the thin film in a predetermined portion to improve crystallinity, a step of forming a gate oxide film, a step of diffusing p or n-type impurities to form a source / drain region, and a step of depositing a metal thin film to form a gate. Forming a pixel switch TFT group and a drive circuit by forming an electrode and a gate bus line, forming an interlayer insulating film, depositing a metal thin film and forming a source electrode and a source bus line,
Forming a group of transparent pixel electrodes.

According to this method, without using the laser annealing method, a group of pixel switching TFTs having a uniform in-plane field-effect mobility of 1 to 25 cm ² / V · s, a source bus line and a gate bus. A TFT array having a driving circuit TFT having a field effect movement of 100 cm ² / V · s or more connected to the pixel switching TFT array via the line is obtained.

In the third and fourth aspects of the present invention, in the step of selectively heating the polycrystalline silicon thin film in the portion where the drive circuit is to be formed to improve the crystallinity, selective annealing is performed by using a laser beam or an infrared lamp. Becomes easier. Further, when heating is performed in an atmosphere containing hydrogen, the annealing effect can be improved.

According to a fifth aspect of the present invention, at least a transparent pixel electrode group formed on a transparent substrate and a pixel switch TFT having a field effect movement of 1 to 25 cm ² / V · s are provided.
Groups, source bus lines and gate bus lines connected to them, and the field effect movement connected to them is 100 cm.
^A liquid crystal is interposed between a first substrate including a drive circuit composed of a group of TFTs or MOS transistors of ² / V · s or more and a second substrate formed of a transparent substrate having a counter electrode formed thereon via an alignment film. The present invention provides a liquid crystal display device characterized by interposing.

According to this configuration, the pixel switch TFT
Since the field effect movement of the group is set to a relatively low value of 1 to 25 cm ² / V · s, the field effect mobility in the plane of the thin film transistor for the pixel switch which needs to form the thin film transistor over a large area is reduced. It is possible to maintain uniformity. Further, by adding a pixel switch TFT group and a driving circuit composed of a TFT or MOS transistor group having a field effect movement of 100 cm ² / V · s or more connected via a source bus line and a gate bus line. Thus, a display device capable of high-frequency driving can be obtained.

In the fifth invention, a transparent liquid crystal display device is provided by forming a counter electrode formed on a second substrate with a transparent conductive film and forming a color filter between the counter electrode and the transparent substrate. it can. In addition, a reflective liquid crystal display device can be provided by forming a counter electrode formed on the second substrate with a reflective film containing metal Al as a main component and forming a color filter on the surface of the counter electrode.

According to a sixth aspect of the present invention, there is provided at least a first comb-shaped transparent pixel electrode group formed on a transparent substrate and a pixel switch TFT group having a field effect movement of 1 to 25 cm ² / V · s. A driving circuit composed of a source bus line and a gate bus line connected to them, and a TFT or MOS transistor group connected to them and having a field effect movement of 100 cm ² / V · s or more, and the first comb-shaped pixel electrode IPS-type liquid crystal display device characterized in that liquid crystal is interposed between a first substrate including a second comb-shaped electrode facing the first substrate and a second substrate made of a transparent substrate with an alignment film interposed therebetween.

According to this configuration, the pixel switch TFT
Since the field effect movement of the group is set to a relatively low value of 1 to 25 cm ² / V · s, the field effect mobility in the plane of the thin film transistor for the pixel switch which needs to form the thin film transistor over a large area is reduced. It is possible to maintain uniformity. Further, by adding a pixel switch TFT group and a driving circuit composed of a TFT or MOS transistor group having a field effect movement of 100 cm ² / V · s or more connected via a source bus line and a gate bus line. Thus, an IPS type liquid crystal display device which can be driven at a high frequency can be obtained.

In the sixth aspect of the invention, a color IPS type liquid crystal display device can be provided by forming an alignment film on a side of the second substrate made of a transparent substrate which is in contact with the liquid crystal through a color filter. Further, if a reflection film mainly composed of metal Al is formed between the color filter and the transparent substrate, a color IPS type reflection liquid crystal display device can be provided.

A seventh aspect of the present invention is a process for forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate by using a pressure gradient plasma gun, and forming a gate oxide film. Forming a source / drain region by diffusing p or n-type impurities; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film Forming a pixel switch TFT group by forming a source electrode and a source bus line, forming a transparent pixel electrode group, and forming an alignment film on the transparent electrode group side surface.
Forming an alignment film after forming a counter electrode on a transparent substrate to form a second substrate; and aligning the alignment film of the first substrate and the alignment film of the second substrate with each other. A step of bonding the periphery of the first substrate and the second substrate together at an arbitrary gap and injecting liquid crystal into the gap, and a step of mounting and connecting an IC chip in which a drive circuit is formed in advance; And a method of manufacturing a liquid crystal display device characterized by the following.

According to this method, a liquid crystal display device having a uniform field effect mobility in a plane and having a group of pixel switching TFTs of 1 to 25 cm ² / V · s can be obtained without using a laser annealing method. Can be

An eighth aspect of the present invention is a method of forming a polycrystalline silicon thin film by evaporating a silicon material on a transparent substrate by using a pressure gradient plasma gun and performing ion plating, and forming a driving circuit. A step of selectively heating the thin film in a predetermined portion to improve the crystallinity, a step of forming a gate oxide film, a step of forming a source / drain region by diffusing p or n-type impurities, and a step of depositing a metal thin film. A step of forming a gate electrode and a gate bus line, a step of forming an interlayer insulating film, a step of depositing a metal thin film to form a source electrode and a source bus line, and a step of forming an alignment film on the transparent electrode group side surface Forming a first substrate on which a group of switching TFTs and a driving circuit are formed; forming an alignment film after forming a counter electrode on a transparent substrate; And bonding an alignment film on the first substrate surface and an alignment film on the second substrate surface to each other, and bonding the periphery of the first substrate and the second substrate to the second substrate at an arbitrary gap. Provided is a method for manufacturing a liquid crystal display device, which includes a step of injecting liquid crystal.

According to this method, without using the laser annealing method, a TFT group for pixel switches having a uniform in-plane field effect mobility and 1 to 25 cm ² / V · s, a source bus line and a gate bus A liquid crystal display device having a driving circuit TFT having a field effect movement of 100 cm ² / V · s or more connected to the pixel switching TFT array via the line is obtained.

In the seventh and eighth inventions, when forming the second substrate, a color filter is previously formed on the surface of the transparent substrate, and a transparent conductive film for the counter electrode is formed thereon, whereby a transmission liquid crystal display device can be manufactured.

When forming the second substrate, a transparent conductive film mainly composed of metal Al is formed as a counter electrode on the surface of the transparent substrate in advance, and a color filter is formed thereon. Can be manufactured. Furthermore,
When a nematic liquid crystal is used as a liquid crystal to be used, a TN liquid crystal display device can be manufactured.

A ninth aspect of the present invention is a method for forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material using a pressure gradient plasma gun on a transparent substrate. Forming a source / drain region by diffusing p or n-type impurities; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film Forming a group of pixel switching TFTs by forming a source electrode and a source bus line; forming a first group of transparent comb-shaped pixel electrodes; and forming a second group of transparent comb-shaped pixel electrodes. First
Forming a first substrate by forming an alignment film on the surface of the second transparent electrode group side, and forming a second substrate having an alignment film formed on the surface of the transparent substrate; A process in which the alignment films of the second substrate are opposed to each other, and the first substrate and the second substrate are bonded to each other with an arbitrary gap, and liquid crystal is injected into the gap; And a method for manufacturing an IPS-type liquid crystal display device.

According to this method, an IPS-type liquid crystal display device having a uniform in-plane field effect mobility and having a pixel switch TFT group of 1 to 25 cm ² / V · s without using a laser annealing method. Is obtained.

A tenth aspect of the present invention is a method for forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate using a pressure gradient plasma gun and forming a driving circuit. A step of selectively heating the thin film in a predetermined portion to improve the crystallinity, a step of forming a gate oxide film, a step of forming a source / drain region by diffusing p or n-type impurities, and a step of depositing a metal thin film. Forming a pixel switch TFT group and a driving circuit by forming a gate electrode and a gate bus line, forming an interlayer insulating film, depositing a metal thin film and forming a source electrode and a source bus line, Forming a first group of transparent comb-shaped pixel electrodes;
Forming a first substrate by forming a transparent comb-shaped pixel electrode group, forming an alignment film on the first and second transparent electrode group side surfaces, and forming a counter electrode on the transparent substrate Forming an alignment film after forming the second substrate, and forming the alignment film of the first substrate and the alignment film of the second substrate so as to face each other at an arbitrary gap.
And bonding the periphery of the substrate to the substrate and injecting a liquid crystal into the gap.

According to this method, without using the laser annealing method, a TFT group for pixel switches having a uniform in-plane field effect mobility of 1 to 25 cm ² / V · s, a source bus line and a gate bus. A PS-type liquid crystal display device having a driving circuit TFT having a field effect movement of 100 cm ² / V · s or more connected to the pixel switching TFT array via the line can be obtained.

In the ninth and tenth inventions, when the second substrate is formed, a color filter is formed on the surface of the transparent substrate in advance, and then a transparent conductive film for the counter electrode is formed.
Type transmissive liquid crystal display device can be manufactured.

When the second substrate is formed, a reflective film composed mainly of metal Al is formed as a counter electrode on the surface of the transparent substrate in advance, and then a color filter is formed thereon. Can be manufactured. Furthermore, if a nematic liquid crystal having excellent response characteristics is used, an IPS type liquid crystal display device having excellent response characteristics can be manufactured.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a method for manufacturing a liquid crystal display device (particularly, a method for manufacturing a thin film transistor) according to an embodiment of the present invention will be described. Note that, in the embodiment described below, a case is described in which an inexpensive glass substrate is used as a substrate although it can withstand only in a low temperature range of 600 ° C. or lower. Needless to say, the present invention can be applied to a case where a quartz substrate that can withstand high temperatures is used as the substrate. The present invention also provides
It can be used for various liquid crystal display devices such as a transmission type and a reflection type.

The most important feature of the present invention is that when polysilicon is formed on a glass substrate as a transparent substrate, an amorphous silicon layer is formed in advance, as in the prior art.
The amorphous silicon layer is not melted and polycrystallized (recrystallized), but the field effect mobility becomes 1 to 1 when the silicon semiconductor layer is deposited on the glass substrate from the beginning.
It is a 25 cm ² / V · s polysilicon layer. That is, the present invention seeks to form a highly uniform polysilicon layer on a glass substrate without going through an excimer laser annealing process of an amorphous silicon layer that causes in-plane field-effect mobility non-uniformity. It is assumed that.

According to this structure, a polysilicon layer having a field-effect mobility approximately 2 to 50 times higher than that of amorphous silicon can be formed with a uniform field-effect mobility in a plane. This is advantageous for forming a thin film transistor for a pixel switch which is formed in an array and needs to be formed.

(Embodiment 1) FIG. 1 is a sectional view showing a manufacturing process of a thin film transistor according to Embodiment 1 of the present invention. In FIG. 1, 1 is a glass substrate, and 2 is formed on the substrate. Buffer layer, 4 is a polysilicon layer, 5 is a gate insulating layer, 6 is a gate electrode, 7 is a source region, 8 is a drain region, 9 is a contact hole, 10 is a source electrode, and 11 is a drain electrode. In FIG. 1, a description will be given by taking a manufacturing process sectional view of one thin film transistor as an example. However, this thin film transistor is actually a pixel portion and a gate driving device as shown in FIG. It is formed together with a driving circuit section such as a circuit section and a source driving circuit section. The thin film transistor formed in the pixel portion is a thin film transistor for a pixel switch formed in an array, and the thin film transistor formed in the drive circuit portion is connected to the thin film transistor for a pixel switch.

Hereinafter, a method of manufacturing a thin film transistor according to the present embodiment will be described with reference to FIG.

First, on the glass substrate 1, for example, a 600 nm thick Si ₃ N ₄ and a 1000 SiO
_Then , a polysilicon layer 4 is formed on the buffer layer 2 (FIG. 1A). A specific method for forming the polysilicon layer 4 will be described later.

Next, for example, 200
A gate insulating layer 5 made of Si ₃ N ₄ having a thickness of 1500 and SiO _{2 having} a thickness of 1500 is formed. Then, a gate electrode 6 made of, for example, 6000 Mo is formed on the gate insulating layer 5, and phosphorus ions are implanted into the polysilicon layer 4 using the gate electrode 6 as a mask (FIG. 1B).

Thereafter, by irradiating an excimer laser beam, the phosphorus ions implanted into the polysilicon layer 4 in the step of FIG. 1B are activated to form a source region 10 and a drain region 9 (FIG. 1). (C)). At this time, a lamp annealing method could be used instead of the laser to activate the phosphorus ions.

Finally, the gate insulating layer 5 is etched to form a contact hole 9 reaching the source region 7 and the drain region 8.
When the source electrode 10 and the drain electrode 11 are formed by embedding Al having a thickness of 2 nm, a low-temperature polysilicon thin film transistor (TFT) can be completed.

In the same manner, a polycrystalline silicon thin film is formed on a transparent substrate by evaporating and ion-plating the silicon material using a pressure gradient plasma gun. Thereafter, a step of forming a gate oxide film and p or n
The source / drain regions are formed by diffusing the mold impurities. Next, a metal thin film is deposited to form a gate electrode and a gate bus line, and an interlayer insulating film is formed. Then, a metal thin film is deposited to form a source electrode and a source bus line to form a pixel switch T.
Form an FT group. Further, a transparent pixel electrode group is formed,
By mounting and connecting an IC chip in which a drive circuit was previously formed, a TFT array for a liquid crystal display device could be manufactured.

Further, an alignment film is formed on the surface of the TFT array for a liquid crystal display device manufactured as described above to form a first substrate. On the other hand, a second substrate in which a counter electrode and an alignment film are formed on a transparent substrate prepared in another process is prepared. After that, the alignment film of the first substrate and the alignment film of the second substrate are placed facing each other, and the periphery of the first substrate and the second substrate are adhered at an arbitrary gap, and liquid crystal is injected into the gap. After that, sealing was performed, and further, an IC chip in which a drive circuit was previously formed was attached and connected, whereby a liquid crystal display device was manufactured.

Further, in the same manner, a polycrystalline silicon thin film is formed by evaporating and ion-plating a silicon material on a transparent substrate by using a pressure gradient plasma gun, and then a gate oxide film is formed. Thereafter, a p-type or n-type impurity is diffused to form a source / drain region, and then a metal thin film is deposited to form a gate electrode and a gate bus line. Further, after forming an interlayer insulating film, a metal thin film is deposited to form a source electrode and a source bus line, thereby forming a pixel switch TFT group. Next, after forming the first transparent comb pixel electrode group and the second transparent comb pixel electrode group separately, an alignment film is formed on the first and second transparent electrode group side surfaces, and the first substrate is formed. create. On the other hand, a second substrate having an alignment film formed on the surface of the transparent substrate is prepared. After that, the alignment films of the first and second substrates are opposed to each other, and the first substrate and the second substrate are adhered to each other with an arbitrary gap, liquid crystal is injected into the gap, sealed, and then sealed. By mounting and connecting an IC chip having a driving circuit, an IPS liquid crystal display device could be manufactured.

In the case of a transmissive liquid crystal display device, a color filter is formed on the surface of a transparent substrate in advance, a transparent conductive film for a counter electrode is formed thereon, and a color filter is formed between the counter electrode and the transparent substrate. In the case of a reflective liquid crystal display device, a reflective conductive film mainly composed of metal Al is formed as a counter electrode on the transparent substrate surface, and a color filter is formed thereon. Good.

According to the above method, when the polysilicon layer 4 is formed, the silicon semiconductor layer is already formed so as to become polysilicon at the deposition stage, and after exposing amorphous silicon to excimer laser, Since the annealing process is not performed, a polysilicon layer having uniform field effect mobility in the in-plane direction can be formed. The field effect mobility of amorphous silicon of a thin film transistor using amorphous silicon as an active layer, which is used in a liquid crystal display device generally commercially available at present, is about 0.5 cm ² / V · s. The polysilicon layer formed according to the above mode is ¹ to 25 cm ² /
A field effect mobility of about Vsec was obtained. That is,
An excellent thin film transistor having characteristics usable for a pixel switch could be obtained without annealing.

Next, a kind of ion plating method for forming the polysilicon layer 4 so as to become a polysilicon layer when deposited on the glass substrate 1 as described above will be described in detail with reference to FIG. I do.

FIG. 2 is a schematic sectional view of an apparatus used for forming a polysilicon layer in the method of manufacturing a thin film transistor according to the present invention.
7 is a glass substrate on which a polysilicon layer is deposited, 18 is a sample stage on which a glass substrate 17 is placed, 19 is an evaporation sample (polysilicon tablet) as a raw material of the polysilicon layer, 20
Is a pressure gradient type plasma gun as a plasma generation means used for evaporating the evaporated sample 19 and exciting the evaporated silicon particles by plasma, 21 is a plasma region formed by the plasma generation means 20,
Reference numeral 22 denotes silicon fine particles which evaporate from the silicon tablet by the thermal energy of the DC arc discharge by the plasma generating means and are excited in the plasma region 21.

In the present embodiment, first, Ar gas is excited by the plasma generating means 20 and the high density plasma region 2 is excited.
Form one. At this time, the silicon particles evaporate from the surface of the evaporation sample 19 of the polysilicon tablet by the thermal energy of the DC arc discharge by the plasma generation means 20. Thereafter, the evaporated silicon particles are removed from the plasma region 21.
Glass substrate 1 placed on sample stage 18 excited in
7 and a polysilicon layer is deposited and formed on the glass substrate 17.

For example, using a borosilicate glass substrate previously coated with 500 nm of silica, the discharge current of the pressure gradient plasma gun is set to about 100 A at a degree of vacuum of 3 × 10 ^-4 Torr, and the substrate temperature is set to 200 ° C. When evaporation was performed while heating, a silicon film of about 1000 angstroms could be deposited in 20 seconds. Therefore, when an n-channel TFT is formed using this polysilicon thin film and the transistor characteristics are evaluated, 5 cm ² / V
・ The field effect mobility of s was shown. This value is about ten times that of amorphous silicon, indicating that a thin film transistor (TFT) array of a practical level can be obtained as it is.

Further, the polysilicon film formed by the above method exhibited good characteristics as shown below.

First, according to the present embodiment, most of the excited silicon particles 22 serving as the material for forming the polysilicon layer reach the glass substrate 17 in a state where most of them are sufficiently ionized. The silicon particles have sufficient energy even when they reach the glass substrate 17. In other words, even after reaching the glass substrate 17, microscopically, it still has energy that can move on the substrate surface and can move to a stable point (migration is possible). Even when microscopic defects occur in the crystal of the silicon thin film when the excited silicon particles 22 reach and form the silicon thin film, the silicon particles migrate so that the defects disappear, and in fact, A polysilicon layer having a crystal grain size of about 500 to 700 nm with very few defects existing therein and having good crystallinity was obtained. Naturally, when the silicon particles migrate as described above, the denseness of the finally obtained polysilicon thin film has also been improved. Such a polysilicon thin film having good crystallinity naturally has a high field-effect mobility. When an n-channel TFT is formed using the polysilicon thin film and transistor characteristics are evaluated, conventional polysilicon is used. Compared with the TFT, a field-effect mobility of 5 to 25 cm ² / V · s, which is a high field-effect mobility, was obtained, and a practical-use thin-film transistor usable as a pixel switch as it was was obtained.

Second, according to the present embodiment, since a pressure gradient plasma gun is used, polysilicon can be deposited at a higher speed and with a larger area as compared with the conventional ion plating method. Further, since the evaporation area of the silicon raw material as the evaporation sample is large, when the silicon particles excited and ionized are viewed from the glass substrate 17 side on which the polysilicon layer is formed, the silicon particles fly from various directions. As a result, a polysilicon thin film having excellent uniformity can be obtained.

Third, according to the present embodiment, the glass substrate 17 on which the polysilicon layer is formed is placed outside the plasma region 21 formed by the pressure gradient plasma gun, The temperature of the glass substrate 17 does not rise due to the collision of the plasma particles in the glass substrate 17. As a matter of fact, when trying to deposit polysilicon as described above, the temperature of the glass substrate 17 could be reduced to 100 ° C. or less.

In the present invention, it is also possible to use the device shown in FIG. 3 instead of the device shown in FIG. The apparatus shown in FIG. 3 can form a polysilicon layer using only ionized particles.

The apparatus shown in FIG. 3 is an apparatus using a pressure gradient plasma gun in the same manner as in FIG. 2 described above, 23 is a vacuum vessel, 24 is a glass substrate for depositing a polysilicon layer, 25
Is a sample stage on which a glass substrate 24 is placed, 26 is an evaporating sample serving as a raw material of a polysilicon layer, 27 is a pressure as a plasma generating means used for evaporating the evaporating sample 26 and exciting the evaporated silicon particles by plasma A gradient type plasma gun, 28 is a voltage applying unit, 29 is a plasma region formed by the plasma generating unit 27,
Numeral 30 denotes an insulator for surely separating the glass substrate 24 from the plasma region 29, and numeral 31 evaporates from the evaporation sample by the heat energy of the DC arc discharge by the plasma generating means and is excited in the plasma region 29. The silicon particles applied to the glass substrate 24 are shown.

Using the apparatus shown in FIG. 3, a polysilicon layer can be formed on the glass substrate 24 as described below. First, Ar gas is excited by the plasma generating means 27 to form a high-density plasma region 29. At this time, the silicon particles evaporate from the surface of the evaporating sample 26 by the heat energy of the DC arc discharge by the plasma generating means 27, and thereafter the evaporated silicon particles are excited in the plasma region 29. Here, in the apparatus shown in FIG. 2 described above, the glass substrate is installed above the silicon evaporating, but in the apparatus shown in FIG. 3, the glass substrate 24 is in a direction different from the direction in which the silicon evaporates. It is installed below. In order to irradiate the silicon particles on the glass substrate 24 provided below the semiconductor substrate, a voltage applying means 28 is provided. The glass substrate 2 by the voltage applying means 28
When a voltage is applied to the sample stage 25 on which the sample 4 is placed, an electric field is formed between the plasma region 29 where the excited silicon particles are present and the glass substrate 24, and the ionization existing in the plasma region 29 is caused by the electric field. Only the extracted silicon particles 31 are extracted and irradiated on the glass substrate 24.

As described above, in the example shown in FIG. 2, since high-density plasma is formed by using the pressure gradient plasma gun, most of the silicon particles evaporated from the evaporation sample are ionized. The glass substrate is irradiated with a considerable amount of energy. When the apparatus shown in FIG. 3 is used, excited silicon particles (such as ionized particles and neutral particles) existing in the plasma region 29 are used. 2 can selectively irradiate the ionized silicon particles 31 onto the glass substrate 24, so that migration after being deposited on the glass substrate 24 is easier than in the apparatus shown in FIG. Can be raised.

Although the example of FIG. 3 has been described using a pressure gradient plasma gun which also serves as a means for evaporating the evaporated sample and a means for forming a plasma region for exciting the evaporated particles, the apparatus shown in FIG. In this method, instead of evaporating and ionizing a silicon material using a pressure gradient plasma gun, a method of introducing a silane gas and exciting it with high frequency was somewhat contaminated with hydrogen, but almost the same film formation was possible. .

Instead of using a pressure gradient type plasma gun, an ordinary ion plating method may be used. In this case, although it is difficult to perform high-speed film formation as compared with the case where a pressure gradient plasma gun is used,
It was possible to form a polysilicon layer using only ionized particles.

(Embodiment 2) Next, a method of manufacturing a thin film transistor according to Embodiment 2 of the present invention will be described. This embodiment is different from the first embodiment in that
After forming a polysilicon layer on a glass substrate so as to become a polysilicon layer at the deposition stage, the drive circuit section is further selectively subjected to excimer laser annealing to further increase the field effect mobility of the drive circuit section. It is to have a step of improving.

Note that the above-mentioned drive circuit section is the same as that shown in FIG.
Gate drive circuit unit 14 incorporating a TFT and TF
It refers to the source drive circuit unit 15 containing T. In the following example, an excimer laser annealing will be described as an example of a heat treatment for further improving the crystallinity of the polysilicon layer.However, an infrared lamp may be used, or heating may be performed in an atmosphere containing hydrogen. Is also good.

Therefore, in the method of manufacturing a thin film transistor according to the present embodiment, the above-described step of FIG. 1A is basically performed until excimer laser annealing is performed, and thereafter, only the drive circuit portion is selected. The polysilicon layer 4 is melted and recrystallized by irradiating an excimer laser beam, and the value of the field effect mobility is further increased to 100 to 400 cm ² / V.
・ It will be increased to about s. The irradiation conditions of the excimer laser light at this time are 300 to 450 m.
It is about J / cm ² . Further, the subsequent steps of the thin film transistor of the drive circuit portion irradiated with the excimer laser light and the thin film transistor of the pixel portion not irradiated with the excimer laser light are the same as the steps (b) to (d) of FIG. Here, the description is omitted.

Therefore, similarly, first, a polycrystalline silicon thin film is formed on a transparent substrate by evaporating and ion-plating a silicon material using a pressure gradient plasma gun. Further, the thin film in the portion where the drive circuit is to be formed is selectively heated to improve the crystallinity. After that, a gate oxide film is formed, a p-type or n-type impurity is diffused, a source / drain region is formed, a metal thin film is deposited, a gate electrode and a gate bus line are formed, an interlayer insulating film is formed, and again. A metal thin film is deposited to form a source electrode and a source bus line. After that, the pixel switch T
When the FT group and the drive circuit were formed, and the transparent pixel electrode group was formed, a TFT array for a liquid crystal display device having higher performance than in the first embodiment could be manufactured.

A polycrystalline silicon thin film is formed on a transparent substrate by evaporating and ion-plating a silicon material using a pressure gradient plasma gun. Further, the thin film in the portion where the drive circuit is to be formed is selectively heated to improve the crystallinity. Thereafter, a gate oxide film is formed, and p
Alternatively, diffuse a n-type impurity to form a source / drain region, deposit a metal thin film to form a gate electrode and a gate bus line, form an interlayer insulating film, deposit a metal thin film again, and form a source electrode and a source. Form a bus line. Thereafter, a pixel switch TFT group and a driving circuit are formed, a transparent pixel electrode group is formed, and the first TFT is formed.
After fabricating the array substrate, an alignment film is formed on the surface of the transparent electrode. On the other hand, a counter electrode is formed on a transparent substrate in parallel, and then an alignment film is formed to form a second substrate. This first
The alignment film on the substrate surface and the second alignment film on the substrate surface face each other, and the first substrate and the second substrate are adhered to each other with an arbitrary gap, and liquid crystal is injected into the gap to form a liquid crystal display device. Could be manufactured.

Further, after a silicon material is evaporated and ion-plated on a transparent substrate by using a pressure gradient plasma gun to form a polycrystalline silicon thin film, the thin film in a portion where a drive circuit is to be formed is selectively heated. After forming a gate oxide film, p or n-type impurities were diffused to form source / drain regions.
After that, a thin metal film is further deposited to form a gate electrode and a gate bus line, and then an interlayer insulating film is formed. Further, a thin metal film is deposited to form a source electrode and a source bus line, thereby forming a pixel switch TFT group and a driving circuit. Form. After that, the first transparent comb pixel electrode group and the second transparent comb pixel electrode group are separately formed, and then an alignment film is formed on the first and second transparent electrode group side surfaces to form the first substrate. Produced. On the other hand, after forming a counter electrode on a transparent substrate, an alignment film is formed to prepare a second substrate, and the alignment film of the first substrate and the alignment film of the second substrate are opposed to each other to obtain an arbitrary gap. Then, the periphery of the first substrate and the periphery of the second substrate were adhered to each other, and liquid crystal was injected into the gap and sealed, whereby an IPS type liquid crystal display device could be manufactured.

In the case of a transmission type liquid crystal display device, a color filter is formed on the surface of a transparent substrate in advance, a transparent conductive film for a counter electrode is formed thereon, and a color filter is formed between the counter electrode and the transparent substrate. In the case of a reflective liquid crystal display device, a reflective conductive film mainly composed of metal Al is formed as a counter electrode on the transparent substrate surface, and a color filter is formed thereon. Good.

As described above, in this embodiment, excimer laser annealing is performed only on the thin film transistor formed in the drive circuit portion to selectively increase the field-effect mobility of the drive circuit portion. This is a particularly effective means for increasing the manufacturing efficiency of the liquid crystal display device. When the liquid crystal display device has a large area, problems such as signal delay may occur inevitably, and the characteristics of a thin film transistor formed in a driving circuit portion for performing signal processing are required to have higher speed. Therefore, when a driving circuit for a large-area liquid crystal display device is assumed, a polysilicon layer having a higher field-effect mobility than a polysilicon layer of a thin film transistor formed by the method of the first embodiment is driven. It needs to be formed in the circuit section.

Here, the excimer laser annealing as a means for increasing the field effect mobility of the polysilicon layer in the present embodiment is different from the conventional excimer laser annealing. In other words, the conventional excimer laser annealing for increasing the field-effect mobility also serves as a process for changing amorphous silicon to polysilicon, so that a portion that becomes a nucleus for the growth of crystal grains when converting to polysilicon is used. As described above, it is difficult to obtain a polysilicon layer having unstable field of crystal growth and uniform in-plane field-effect mobility because it is impossible to specify where the occurrence occurs. On the other hand, according to the present invention, since the excimer laser light irradiation is applied to the layer which is already polysilicon, the polysilicon before the excimer laser light irradiation becomes a nucleus at the time of recrystallization, and the crystal becomes It is easy to obtain a polysilicon layer that is stable in growth and has a uniform field effect mobility in the plane.

Further, in this embodiment, since the region where excimer laser annealing is performed is limited to the drive circuit portion, there is an advantage that the region to be irradiated with excimer laser light can be small.

This point will be specifically described with reference to FIG. 5A and 5B are plan views schematically showing a substrate on which a TFT array of a general liquid crystal display device is formed. In FIG. 5, 12 is a glass substrate, and 13 is a glass. A pixel portion on the substrate 12 on which a TFT array element for a pixel switch is formed, 14 is a gate drive circuit portion having a built-in TFT, and 15 is a source drive circuit portion having a built-in TFT.

The difference between the plan views of FIGS. 5A and 5B is the area of the liquid crystal display device, and the display area of FIG. 5B is larger. When a liquid crystal display device having a larger area required in the future is considered (FIG. 5A to FIG.
In the case of (b), if the excimer laser annealing is to be performed after the amorphous silicon is once formed as in the related art, the excimer laser light must be applied to almost the entire surface of the liquid crystal display device. For this reason, as the display area increases, a larger-scale excimer laser beam irradiation device is required (the irradiation width of the excimer laser beam becomes wider), and the stability and uniformity of the laser beam irradiated are considered accordingly. The need arises.

On the other hand, according to the present embodiment, when a larger-area liquid crystal display device as shown in FIG. 5A to FIG. Although the area of the drive circuit portion, which is a region to be increased, increases, but its width does not change much, the large-scale excimer laser light irradiation device as described above is not required. Therefore, according to the present embodiment, it becomes possible to stably form a polysilicon layer having further increased field-effect mobility with uniform characteristics in a plane. When the scanning directions 33a and 33b for irradiating the line beams 32a and 32b of the excimer laser light while scanning are parallel to the scanning directions of the source and gate signals, efficient use of a laser having a short beam width is possible. Become.

As described above, in this embodiment mode, an excimer laser beam irradiation for increasing the field effect mobility is performed on the thin film transistor region for an array of pixel switches constituting the pixel portion of the liquid crystal display device. Not. According to the present inventor's view, the thin film transistor forming the pixel portion does not require complicated signal processing required for the thin film transistor of the drive circuit portion, and the method described in Embodiment 1 above is used. Considering that the formed polysilicon layer has a field effect mobility of at least 10 times or more as compared with the conventional amorphous silicon even without irradiation with excimer laser light, the polysilicon layer of the thin film transistor constituting the pixel portion is considered. It is not necessary to perform excimer laser annealing on the substrate. That is, according to the present embodiment, excimer laser annealing is performed only on the minimum necessary region, and a thin film transistor having sufficient display characteristics of the liquid crystal display device can be easily formed.

If, for some reason, the thin film transistor forming the pixel portion requires the same field-effect mobility as the thin film transistor forming the drive circuit portion, the pixel portion may be subjected to excimer laser annealing. Needless to say. In this case, it is necessary to irradiate a large area region such as a pixel portion with an excimer laser beam, so that the above-described inconvenience arises. Compared with silicon laser annealing, the field effect mobility is higher (depending on irradiation conditions, but 100 to 400
cm ² / V · S was obtained. ), TFTs including thin film transistors with good characteristics with uniform field effect mobility in the plane
An array was obtained.

In the above embodiment, not only a thin film transistor for a pixel switch but also a thin film transistor for a driving circuit connected to the thin film transistor for a pixel switch are described on an example in which they are formed on a glass substrate. The method for forming a polysilicon layer according to the present invention is a very useful method for forming a polysilicon layer having a uniform field effect mobility over a large area. The circuit may be formed separately in a single-crystal silicon IC chip and then connected to the above-described pixel switch thin film transistor. In this case, the thin film transistor for the pixel switch can be uniform and has a higher field-effect mobility than amorphous silicon, while the driving circuit portion can be formed using single crystal silicon. Further, there is an effect that high-speed signal processing can be performed.

(Embodiment 3) Next, a method of manufacturing a thin film transistor according to Embodiment 3 of the present invention will be described below. This embodiment is different from the first embodiment in that a silicon semiconductor layer serving as an active layer of a thin film transistor is not only made of polysilicon at the stage of deposition but also made of polysilicon.
The point is that the gate insulating layer is also formed by the method described in Embodiment 1.

Therefore, the method of manufacturing a thin film transistor according to the present embodiment is the same as that of the first embodiment up to the step of FIG. 1A, and the gate insulating layer 5 is formed in the step of FIG. At the time of formation, a silicon nitride layer or a silicon oxide film layer is formed using, for example, the apparatus shown in FIG. When the gate insulating layer 5 is formed, Si ₃ N ₄ or SiO ₂ having the same material composition as the gate insulating layer 5 is used as an evaporation sample.
The other conditions may be the same as the conditions for forming the polysilicon thin film of the first embodiment. FIG.
Steps after (b) are the same as the steps (c) and (d) in FIG. 1, and thus description thereof is omitted here.

When the gate insulating layer of the thin film transistor is formed as described above, if the material is excited and formed on the polysilicon layer using the same material as the gate insulating layer as an evaporation sample, the following advantages are obtained. .

First, impurities in the gate insulating layer are reduced. Conventionally, in forming a SiO ₂ as a gate insulating layer, or a silane-based gas, but not have a material of TEOS-based, SiO ₂ was created by using a silane-based gas is OH
And the TEOS-based material contains carbon. Such impurities are originally unnecessary, but are inevitably included in the gate insulating layer due to the manufacturing method. On the other hand, according to the present embodiment, the starting material for forming the gate insulating layer is, for example, Si ₃ N ₄ or SiO _3.
Since it is _2, it is possible to fundamentally prevent extra impurities from being mixed. For example, in the case of a SiO ₂ film, Nss is reduced by 1
0 ¹² or less. In addition, conventionally, it was necessary to perform dehydrogenation treatment for the purpose of removing impurities, but according to the present embodiment, such a step was unnecessary.

Second, when the gate insulating layer is formed by using a pressure gradient plasma gun as shown in FIG. 2, the evaporation sample is formed over a large area at a high speed and in a large area as in the case of forming the polysilicon layer. Since Si ₃ N ₄ and SiO ₂ can be evaporated, the gate insulating layer itself has uniform characteristics in the plane and can be a dense layer.

Third, a gate insulating layer is formed continuously (without exposing the polysilicon surface to the air) on the polysilicon layer, which is the active layer of the thin film transistor, particularly by employing the load lock method. Then, contamination at the interface between the polysilicon layer and the gate insulating layer can be minimized. It is known that the interface state between the active layer made of polysilicon and the gate insulating layer greatly affects the characteristics of the thin film transistor. According to this embodiment, the region can be extremely cleaned.
As a result, it is possible to minimize variations in Vt characteristics of each thin film transistor.

In the third embodiment, the first embodiment is used.
Although the example in which the gate insulating layer is also formed by the method shown in FIG. 2 has been described with respect to the method for manufacturing the thin film transistor of the second embodiment, the method shown in FIG. It is needless to say that the same effect can be obtained even if it is formed as follows.

[0096]

As described above, according to the present invention, even if laser annealing is not performed, a large area is uniform and the field effect mobility is 2 times higher than that of conventional amorphous silicon.
It is possible to obtain a polysilicon thin film which is about 50 times higher, and has the effect of greatly improving the performance of an arrayed thin film transistor as a pixel switch formed on the thin film. Also,
The field effect mobility of the obtained thin film field effect transistor can be formed uniformly in the plane. Therefore,
Display unevenness can be minimized.
This is particularly effective for improving the performance of a liquid crystal display device having a large display area.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a manufacturing process of a thin film transistor according to an embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus for forming a polysilicon layer in the method for manufacturing a thin film transistor according to the embodiment of the present invention.

FIG. 3 is a schematic diagram of an apparatus for forming a polysilicon layer in the method for manufacturing a thin film transistor according to the embodiment of the present invention.

FIG. 4 is a sectional view of a manufacturing process of a conventional thin film transistor.

FIG. 5 is a plan view schematically showing a liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Buffer layer 3 Amorphous silicon layer 4 Polysilicon layer 5 Gate insulating layer 6 Gate electrode 7 Source region 8 Drain region 9 Contact hole 10 Source electrode 11 Drain electrode 12 Glass substrate 13 Pixel part 14 Gate drive circuit part 15 Source drive Circuit section 16 Vacuum container 17 Glass substrate 18 Sample table 19 Evaporated sample 20 Plasma generating means 21 Plasma area 22 Excited silicon particles 23 Vacuum container 24 Glass substrate 25 Sample table 26 Evaporated sample 27 Plasma generating means 28 Voltage applying means 29 Plasma area Reference Signs List 30 Insulator 31 Silicon particle 32a, 32b Line beam shape 33a, 33b Line beam scanning direction

Claims (24)

[Claims] 1. A pixel comprising: a transparent pixel electrode group and a pixel switch TFT group formed on a transparent substrate; a source bus line and a gate bus line connected thereto; and a driving circuit connected thereto. A liquid crystal characterized in that the field effect movement of the group of switching TFTs is 1 to 25 cm ² / V · s, and the field effect movement of the group of TFTs or MOS transistors constituting the drive circuit is 100 cm ² / V · s or more. TFT array for display device. 2. A first comb-shaped transparent pixel electrode group formed on a transparent substrate, a pixel switch TFT group having a field effect movement of 1 to 25 cm ² / V · s, and a source bus line and a gate connected thereto. Bus lines and TFTs or Ms connected to them that have a field effect movement of 100 cm ² / V · s or more
A TFT array for a liquid crystal display device, comprising: a driving circuit constituted by an OS transistor group; and a second comb-shaped electrode facing the first comb-shaped pixel electrode. 3. The TFT array for a liquid crystal display device according to claim 1, wherein the TFT array for a pixel switch is an n-channel type. 4. The TFT array for a liquid crystal display device according to claim 3, wherein the field effect movement of the n-channel type TFT array for pixel switch is 5 to 25 cm ² / V · s. 5. A step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate by using a pressure gradient plasma gun and a step of forming a gate oxide film, and removing p or n-type impurities. Forming a source / drain region by diffusion; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film to form a source electrode and a source bus line And T for pixel switch
A method for manufacturing a TFT array for a liquid crystal display device, comprising a step of forming an FT group, a step of forming a transparent pixel electrode group, and a step of mounting and connecting an IC chip in which a drive circuit is formed in advance. 6. A step of forming a polycrystalline silicon thin film on a transparent substrate by evaporating and ion-plating a silicon material by using a pressure gradient plasma gun, and selectively heating the thin film in a portion where a drive circuit is to be formed. To improve the crystallinity by forming, a step of forming a gate oxide film, and p or n
Forming a source / drain region by diffusing a type impurity, depositing a metal thin film and forming a gate electrode and a gate bus line, forming an interlayer insulating film, depositing a metal thin film and forming a source electrode and a source bus line. A method of manufacturing a TFT array for a liquid crystal display device, comprising: a step of forming a pixel switch TFT group and a drive circuit by forming; and a step of forming a transparent pixel electrode group. 7. A step of selectively heating a polycrystalline silicon thin film at a portion where a drive circuit is to be formed to improve crystallinity.
7. The method for manufacturing a TFT array for a liquid crystal display device according to claim 5, wherein a laser beam or an infrared lamp is used. 8. The method according to claim 5, wherein in the step of selectively heating the thin film in the portion where the drive circuit is to be formed to improve crystallinity, the thin film is heated in an atmosphere containing hydrogen. A method for manufacturing a TFT array for a liquid crystal display device. 9. A transparent pixel electrode group formed on a transparent substrate, a pixel switch TFT group having a field effect movement of 1 to 25 cm ² / V · s, a source bus line and a gate bus line connected thereto, and the like. Field-effect movement connected to
A first substrate including a driving circuit composed of a group of TFTs or MOS transistors of not less than 00 cm ² / V · s;
A liquid crystal display device comprising a second substrate made of a transparent substrate on which a counter electrode is formed, and a liquid crystal interposed between a second substrate and an alignment film. 10. The device according to claim 9, wherein the counter electrode formed on the second substrate is made of a transparent conductive film, and a color filter is formed between the counter electrode and the transparent substrate. The liquid crystal display device according to the above. 11. A method according to claim 11, wherein the counter electrode formed on the second substrate is formed of a reflection film containing metal Al as a main component, and a color filter is formed on the surface of the counter electrode. Item 10. A liquid crystal display device according to item 9. 12. A first comb-shaped transparent pixel electrode group formed on a transparent substrate, a pixel switch TFT group having a field effect movement of 1 to 25 cm ² / V · s, and a source bus line and a gate connected thereto. A bus line and a driving circuit connected to the driving circuit, the driving circuit comprising a group of TFTs or MOS transistors having a field effect movement of 100 cm ² / V · s or more;
Including a second comb-shaped electrode opposed to the first comb-shaped pixel electrode
IPS-type liquid crystal display device, characterized in that a liquid crystal is sandwiched between the first substrate and a second substrate made of a transparent substrate via an alignment film. 13. The IPS type liquid crystal display device according to claim 12, wherein an alignment film is formed on a side of the second substrate made of a transparent substrate, which is in contact with the liquid crystal, via a color filter. 14. A metal A between a color filter and a transparent substrate.
14. The IPS type liquid crystal display device according to claim 13, wherein a reflection film mainly containing 1 is formed. 15. A step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate using a pressure gradient plasma gun and a step of forming a gate oxide film, and removing p or n-type impurities. Forming a source / drain region by diffusion; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film to form a source electrode and a source bus line Forming a first substrate by forming a pixel switch TFT group, forming a transparent pixel electrode group, forming an alignment film on the transparent electrode group side surface, and forming a first substrate on the transparent substrate. Forming an alignment film after forming a counter electrode on the substrate to form a second substrate; and aligning the alignment film of the first substrate and the alignment film of the second substrate with each other. The method comprises the steps of: adhering the periphery of the first substrate and the second substrate at an arbitrary gap and injecting liquid crystal into the gap; and attaching and connecting an IC chip on which a drive circuit has been formed in advance. Of manufacturing a liquid crystal display device. 16. A step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate using a pressure gradient plasma gun and selectively heating the thin film in a portion where a drive circuit is to be formed. A step of forming a gate oxide film, a step of forming a source / drain region by diffusing p or n-type impurities, and a step of forming a gate electrode and a gate bus line by depositing a metal thin film. The step of forming an interlayer insulating film, the step of depositing a metal thin film to form a source electrode and a source bus line, and the step of forming an alignment film on the transparent electrode group side surface formed a pixel switch TFT group and a drive circuit. A step of forming a first substrate, a step of forming an alignment film after forming a counter electrode on a transparent substrate to form a second substrate, and a step of disposing a surface of the first substrate. Film and the first substrate in any gaps facing each other alignment film of the second surface of the substrate and a second
Bonding the periphery of the substrate to the substrate and injecting liquid crystal into the gap. 17. The liquid crystal display according to claim 15, wherein a color filter is previously formed on the surface of the transparent substrate when forming the second substrate, and a transparent conductive film for the counter electrode is formed thereon. Device manufacturing method. 18. A method according to claim 18, wherein a transparent conductive film mainly composed of metal Al is formed as a counter electrode on the surface of the transparent substrate before forming the second substrate, and a color filter is formed thereon. Item 17. A method for manufacturing a liquid crystal display device according to item 15 or 16. 19. The method according to claim 15, wherein the liquid crystal is a nematic liquid crystal. 20. A step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material using a pressure gradient plasma gun on a transparent substrate, a step of forming a gate oxide film, and a step of removing p-type or n-type impurities. Forming a source / drain region by diffusion; depositing a metal thin film to form a gate electrode and a gate bus line; forming an interlayer insulating film; and depositing a metal thin film to form a source electrode and a source bus line Forming a pixel switch TFT group, forming a first transparent comb pixel electrode group, forming a second transparent comb pixel electrode group, and forming first and second transparent electrode group side surfaces. Forming a first substrate by forming an alignment film on the transparent substrate; forming a second substrate having an alignment film formed on the surface of the transparent substrate; Adhering the periphery of the first substrate and the second substrate at an arbitrary gap with the alignment films of the substrates facing each other, injecting liquid crystal into the gap, and mounting an IC chip on which a drive circuit has been formed in advance A method for manufacturing an IPS-type liquid crystal display device, comprising a step of connecting. 21. A step of forming a polycrystalline silicon thin film by evaporating and ion-plating a silicon material on a transparent substrate using a pressure gradient plasma gun and selectively heating the thin film in a portion where a drive circuit is to be formed. A step of forming a gate oxide film, a step of forming a source / drain region by diffusing p or n-type impurities, and a step of forming a gate electrode and a gate bus line by depositing a metal thin film. Forming a pixel switch TFT group and a drive circuit by forming an interlayer insulating film and depositing a metal thin film to form a source electrode and a source bus line; and forming a first transparent comb-shaped pixel electrode group. Forming a second group of transparent comb-shaped pixel electrodes;
Forming a first substrate by forming an alignment film on the surface of the second transparent electrode group side, and forming an alignment film after forming a counter electrode on the transparent substrate to form a second substrate. A step of bonding the alignment film of the first substrate and the alignment film of the second substrate to each other, bonding the periphery of the first substrate and the second substrate to an arbitrary gap, and injecting liquid crystal into the gap A method for manufacturing an IPS type liquid crystal display device, comprising the steps of: 22. The method according to claim 20, wherein a color filter is formed on the surface of the transparent substrate before forming the second substrate, and then a transparent conductive film for the counter electrode is formed.
2. The method for manufacturing an IPS type liquid crystal display device according to item 1. 23. A method of manufacturing a second substrate, comprising: forming a reflective conductive film mainly composed of metal Al as a counter electrode on a surface of a transparent substrate in advance; and forming a color filter thereon. Item 20 or 21 IP
A method for manufacturing an S-type liquid crystal display device. 24. The method according to claim 20, wherein the liquid crystal is a nematic liquid crystal.