JPH06167720A - Active matrix substrate and its production - Google Patents

Abstract

PURPOSE:To provide an active matrix substrate with which the high-mobility characteristics required for TFTs for display and the low-off current characteristics required for TFTs for driving are compatibly obtd. CONSTITUTION:The TFTs (a), (b) for driving are formed by continuously laminating a semiconductor layer 4a and a gate insulating film 5, then patterning the layer and the film to island shapes. The boundaries between the semiconductor layers 4a and the gate insulating films 5 are good and the insulating films 4a are formed to a large film thickness. The TFTs (c) for display are formed by forming the semiconductor layer 4b to a small film thickness and making the resistance of the TFTs higher to decrease off currents and prevent the degradation in the insulation characteristic in the level difference parts of the gate insulating films 3. Further, side wall insulators are formed on the side walls of the gate electrodes 4b and, therefore, these insulators serve as a mask at the time of forming source regions and drain regions. Parts where these impurity ions are implanted or parts 14, 15 where these impurity ions are not implanted are formed among channel parts 20b and the source regions 12b and the drain regions 13b. The off currents at the time of reverse gate bias are thus decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix substrate used for a liquid crystal display, an image sensor and the like, and more particularly to an active matrix substrate suitably used for an active matrix driving type liquid crystal display and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a driver monolithic active matrix substrate in which a thin film transistor (hereinafter referred to as a TFT) used for driving a liquid crystal display or an image sensor is formed on the same substrate as a display section.

Conventionally, this TFT was manufactured by an IC process, and it was necessary to grow a semiconductor layer, form an insulating film, and activate impurities at a high temperature of about 1000.degree. However, in order to form a TFT over a large area using an inexpensive substrate such as a glass substrate, it is necessary to manufacture it by a low temperature process of 600 ° C. or lower. As a semiconductor layer of a TFT manufactured by such a low temperature process, a polycrystalline silicon film obtained by low temperature solid phase growth using amorphous silicon as a material by annealing at about 600 ° C. is formed over a large area. However, because of its good homogeneity, research is actively conducted.

By the way, since the thin film transistor is generally a field effect type, its characteristics are greatly affected by the interface state between the channel portion of the semiconductor layer (polycrystalline silicon film) and the gate insulating film. In the conventional high temperature process, a good interface state is maintained by forming an interface between the gate insulating film and the channel portion inside the semiconductor layer by a thermal oxidation method.
On the other hand, in the low temperature process, the gate insulating film also needs to be formed at a low temperature, and the thermal oxidation method cannot be used. For this reason,
A method has been proposed in which after forming a semiconductor layer, a gate insulating film is continuously formed without being exposed to the air.

[0005]

However, in the above method, since the sidewall surface of the semiconductor layer is exposed when the gate insulating film and the semiconductor layer are patterned into a predetermined shape, the gate electrode is formed in the subsequent step. At times, the gate electrode and the exposed sidewall of the semiconductor layer come into contact with each other, and the leakage current increases. Therefore, it is necessary to cover the sidewall of the semiconductor layer with the sidewall insulator before forming the gate electrode. When a SiO ₂ film that is often used as a gate insulating film is used,
The sidewall insulator needs to be selectively etchable with the SiO ₂ film.

Further, in the polycrystalline silicon film formed by the low temperature solid phase growth method as described above, the mobility tends to increase as the film thickness increases. On the other hand, the driving TFT formed in the driver circuit portion is required to have high mobility. Therefore, it is necessary to increase the thickness of the polycrystalline silicon film formed as the semiconductor layer. When the gate insulating film is formed after the polycrystalline silicon film is patterned into an island shape, if the thickness of the polycrystalline silicon film is increased to increase the mobility, the gate insulating film on the sidewall portion of the island pattern is increased. The insulation of the film deteriorates. This is because the gate insulating film is less likely to be stacked in the step portion of the polycrystalline silicon film than in the flat portion, and the coverage is poor. Therefore, if the thickness of the polycrystalline silicon film is increased, it is necessary to increase the thickness of the gate insulating film. However, if the thickness of the gate insulating film is increased, the threshold voltage of the TFT is increased and the ON current may be reduced. Therefore, it is difficult to increase the mobility by increasing the thickness of the polycrystalline silicon film.

On the other hand, the display TFT formed in the display section for selecting a pixel is not required to have such high mobility. However, a large O
The N / OFF current ratio is required, and particularly the OFF current is required to be small. Therefore, it is more advantageous to form the polycrystalline silicon film thin to increase the resistance of the TFT.

Therefore, the driving T formed on the same substrate
Different characteristics are required for the FT and the display TFT. In the past, it was difficult to make these different characteristics compatible with each other.

The present invention has been made in order to solve the above problems, has a gate insulating film having excellent insulating properties, and further has a high mobility characteristic and a driving TFT required for a display TFT. It is an object of the present invention to provide a driver monolithic active matrix substrate and a method for manufacturing the same, which can achieve both the low OFF current characteristics required for the above.

[0010]

In the active matrix substrate of the present invention, a display portion having display thin film transistors arranged in a matrix is formed on an insulating substrate, and the display portion of the substrate other than the display portion is formed. In the active matrix substrate in which a drive circuit section having a drive thin film transistor for applying a signal to the display thin film transistor is formed, the display thin film transistor and the drive thin film transistor are both provided on one side with a gate insulating film interposed therebetween. The semiconductor layer has an island-shaped pattern having a drain region, the other has a gate electrode that partially overlaps the semiconductor layer, and the semiconductor layer is arranged on the substrate side.
The gate electrode of the display thin film transistor and the semiconductor layer of the driving thin film transistor are formed of the same material, and the gate insulating film of the driving thin film transistor is formed in the same island pattern as the driving semiconductor layer. Further, the sidewall insulator is formed of the same material on the sidewall of the gate electrode of the display thin film transistor and the sidewalls of the semiconductor layer and the gate insulating film of the driving thin film transistor, thereby achieving the above object.

According to the method of manufacturing an active matrix substrate of the present invention, a display portion having display thin film transistors arranged in a matrix is formed on an insulating substrate, and the display portion is provided on a portion other than the display portion of the substrate. In a method of manufacturing an active matrix substrate in which a drive circuit section having a driving thin film transistor for applying a signal to a thin film transistor is formed, a first semiconductor layer is formed in an island pattern in a display thin film transistor forming portion on the substrate. A step of forming a first insulating film so as to cover substantially the entire surface of the substrate on which the first semiconductor layer is formed, and a second semiconductor layer and a second insulating film on the first insulating film And a step of stacking a layer made of a semiconductor or a conductive material on the second insulating film, the second semiconductor layer, the second
Patterning the insulating film and the layer thereover to form an island-shaped portion in the driving thin film transistor forming portion and a linear portion in the display portion that partially overlaps the first semiconductor layer; and the island-shaped portion. Forming a sidewall insulator on each of the sidewall and the linear portion of the sidewall, and for an upper gate electrode made of a semiconductor or a conductive material to cover the island portion on which the sidewall insulator is formed. And forming a layer for the upper gate electrode of the island-shaped portion and a layer on the second insulating film into a linear shape, and forming a layer of the second insulating film of the linear portion. In the step of removing the upper layer, and in the driving section, ion implantation is performed so that ions reach the second semiconductor layer from the layer side for the upper gate electrode, and in the display section, from the second insulating film side. Ion implantation is performed so that the ions reach the first semiconductor layer, and The source / drain regions and the channel portion are formed in the conductor layer, the layer above the second insulating film of the driving portion and the layer for the upper gate electrode are used as the gate electrode of the driving thin film transistor, and the first portion of the display portion is formed. Forming a source / drain region and a channel part in the semiconductor layer, and using the second semiconductor layer of the display part as a gate electrode of the display thin film transistor, thereby achieving the above object.

[0012]

In the driving TFT, since the sidewall insulator is formed so as to cover the sidewall of the semiconductor layer and the gate insulating film formed in the island pattern, the insulation between the semiconductor layer and the gate electrode is improved. Can be made. In addition, the semiconductor layer and the gate insulating film are successively laminated and then patterned into an island shape, so that the interface between the semiconductor layer and the gate insulating film is not exposed to the atmosphere, and the interface state can be kept favorable. .
Further, it is not necessary to increase the thickness of the gate insulating film in order to maintain the insulating property of the gate insulating film, and the thickness of the semiconductor layer can be increased. As a result, the driving TFT can have high mobility characteristics. Further, by forming a layer to be a lower gate electrode on the island-shaped pattern, a sidewall insulator that covers the sidewall of the island-shaped pattern including the semiconductor layer and the gate insulating film is formed. It does not require selective etching of the material and the gate insulating film.

The semiconductor layer of the display TFT is a driving TFT.
Is formed separately from the semiconductor layer. Therefore, by reducing the film thickness, the resistance of the display TFT is increased and
The current can be reduced. Further, it is possible to prevent the insulating property from being deteriorated in the semiconductor layer step portion of the gate insulating film. Further, a sidewall insulator is formed on the sidewall of the gate electrode. Therefore, when the source / drain regions are formed by implanting the impurity ions into the semiconductor layer, this is used as a mask between the channel portion and the source / drain regions in a portion where a small amount of impurity ions are implanted or not implanted. Can be formed. The OFF current at the time of reverse gate bias can be reduced.

[0014]

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

FIG. 2 shows an example of a schematic configuration diagram of an active matrix substrate. This active matrix substrate is provided with a display section and a driver circuit section on an insulating substrate. A gate bus line 19 and a source bus line 20 are formed vertically and horizontally in the display portion, and a liquid crystal cell 22 is formed near the intersection thereof. A display TFT 21 is connected to each liquid crystal cell 22 so as to selectively perform display. The display TFT 21 is connected to the gate bus line 19 and the source bus line 20. The display portion is selectively driven by the driving TFTs provided in the gate driving circuit 24 and the source driving circuit 25. Here, 23 represents a common electrode.

FIG. 1A is a plan view of a driving TFT portion formed on an active matrix substrate according to an embodiment of the present invention, and FIG. 1B is a plan view of a display TFT portion.
FIG. 11A shows the driving TFT A- in FIG.
A sectional view taken along the line A ′, FIG. 11B is a sectional view taken along the line BB ′ of the driving TFT in FIG. 1A, and FIG. 11C is a sectional view taken along the line B− of the display TFT in FIG. A B'line sectional view is shown.

The driving TFT formed in the driving circuit section is
The source / drain regions 12a and 13a and the channel portion 20 are formed on the insulating film 3 formed on almost the entire surface of the insulating substrate 1.
The semiconductor layer 4a having a and the gate insulating film 5a are formed in an island pattern, and the sidewall insulator 8a is provided so as to cover the sidewall of the island pattern. A lower layer gate electrode 6a and an upper layer gate electrode 10 are formed on the island-shaped pattern so as to face the channel portion, and an interlayer insulating film 16 is formed so as to cover almost the entire surface of the substrate in that state.
Further, through the contact hole 17 provided in the interlayer insulating film 16, the source / drain region 1 of the semiconductor layer is formed.
A TFT is formed by forming a metal wiring 18a which is electrically connected to 2a and 13a and serves as a source wiring and a drain wiring.

The display thin film transistor formed in the display portion has a source region / drain region 12 on the insulating substrate 1.
The semiconductor layer 2 having b · 13b and the channel portion 20b is formed in an island pattern. Between the source / drain regions 12b and 13b and the channel portion 20b, there are formed portions 14 and 15 in which a small amount of impurities are injected or in which a small amount of impurities are not injected. The insulating film 3 formed thereon so as to cover almost the entire surface of the substrate serves as a gate insulating film.
A gate electrode 4b made of the same material as the semiconductor layer 4a of the driving thin film transistor is formed on the gate insulating film 3 so as to face the channel portion, and the insulating film 5 is formed thereon.
b is formed. Then, the sidewall insulator 8 formed of the same material as the sidewall insulator 8a of the driving thin film transistor so as to cover the sidewalls of the gate electrode 4b and the insulating film 5b.
b is formed. The interlayer insulating film 16 is formed so as to cover almost the entire surface of the substrate in that state. Further, through the contact hole 17 provided in the interlayer insulating film 16, the source / drain regions 12b and 13b of the semiconductor layer 2 are provided.
A TFT is formed by forming a metal wiring 18b which is to be a source wiring and a drain wiring electrically connected to.

This active matrix substrate is shown in FIGS.
It is manufactured according to the manufacturing process as shown in FIG. Here, (a) is a TFT of the driving TFT, which is A- in FIG.
A section taken along the line A ', (b) is a driving TFT shown in FIG.
(C) is a display TFT.
1B is a sectional view taken along line BB ′ in FIG.

First, as shown in FIG. 3, on the insulating substrate 1, for example, by the low pressure CVD (chemical vapor deposition) method.
Amorphous silicon is deposited at a substrate temperature of 400 to 600 ° C. This in vacuum or in inert gas, 500-650
A polycrystalline silicon film is formed by annealing at 6 ° C. for 6 to 48 hours. This polycrystalline silicon film is formed into an island pattern by etching to form the semiconductor layer 2 of the display TFT. Here, the thickness of the polycrystalline silicon film is 30 to 15
It was formed as 0 nm. As the insulating substrate 1, a glass substrate, a glass substrate covered with an insulating film, or the like can be used. For forming the amorphous silicon film, SiH ₄ and Si ₂ H ₆ are used as a source gas. The amorphous silicon film can also be obtained by a plasma CVD method. Here, since the polycrystalline silicon film 2 is a semiconductor layer of the display part TFT, it is not required to have high mobility as much as the driving TFT. Therefore, instead of polycrystallizing the amorphous silicon film, the polycrystalline silicon film may be formed from the beginning.

Next, as shown in FIG. 4, an insulating film 3 having a film thickness of 100 to 150 nm to be a gate insulating film of the display TFT is formed so as to cover almost the entire surface of the substrate in this state.
The insulating film 3 is formed by sputtering, atmospheric pressure CVD, low pressure CVD.
Method, a plasma CVD method, or a remote plasma CVD method, and is formed as a SiO ₂ film here.

Next, as shown in FIG. 5, the semiconductor layer 4a of the driving TFT, the polycrystalline silicon film 4 to be the gate electrode 4b of the display TFT, and the SiO ₂ film 5 to be the gate insulating film 5a of the driving TFT. Then, a polycrystalline silicon film 6 to be the lower gate electrode 6a of the driving TFT is formed. The polycrystalline silicon film 4 has a substrate temperature of 400 to 6 by a low pressure CVD method.
It is formed by forming an amorphous silicon film at 00 ° C. and annealing it at 500 to 650 ° C. for 6 to 48 hours in vacuum or in an inert gas. SiH ₄ and Si ₂ H ₆ are used as the source gas for the amorphous silicon film. Here, a relatively thick polycrystalline silicon film having a film thickness of 100 to 300 nm was formed. A polycrystalline silicon film may be formed from the beginning. Alternatively, the amorphous silicon film and the polycrystalline silicon film can be obtained by a plasma CVD method.

Subsequently, the SiO ₂ film 5 is formed by any one of the sputtering method, the atmospheric pressure CVD method, the low pressure CVD method, the plasma CVD method and the remote plasma CVD method. SiO
The formation of the ₂ film 5 is performed through the load lock chamber held in vacuum or in an inert gas after the polycrystalline silicon film 4 is formed, without exposing the polycrystalline silicon film 4 to the atmosphere. Here, the SiO ₂ film 5 having a film thickness of 100 to 150 nm is used.
Was formed. Then, the substrate temperature is set to 60 by the low pressure CVD method.
At 0 ° C., a polycrystalline silicon film 6 having a film thickness of 100 nm is formed.

Next, a resist pattern is formed on the gate electrode formation portions of the driving TFT and the display TFT, and the polycrystalline silicon film 4, the SiO ₂ film 5 and the polycrystalline silicon film 6 are etched. As a result, as shown in FIG. 6, the polycrystalline silicon film 4 having an island pattern is formed in the drive circuit portion.
a, is the SiO ₂ film 5a and the polycrystalline silicon film 6a is formed, the display section gate electrode 4b made of a polysilicon film, the insulating film 5b and the polycrystalline silicon film 6b made of SiO ₂ film is formed. Each layer can be formed by anisotropic etching by a reactive ion etching method. Here, the side surfaces of the island pattern after etching were formed so as to be perpendicular to the substrate. A mixed gas of SF ₆ and CCl ₄ is used as an etching gas for the polycrystalline silicon film, and CHF ₃ is used as an etching gas for the SiO ₂ film.
Gas was used.

Subsequently, a SiO ₂ film having a film thickness of 300 to 500 nm is formed by the atmospheric pressure CVD method and anisotropically etched by the reactive ion etching method.
Side wall insulators 8a and 8b, respectively, as shown in FIG.
It is formed in the drive circuit portion and the display portion. Sidewall insulator 8a,
For forming 8b, any film forming method having good step coverage can be used. For example, TEOS (Te
It can be formed by performing anisotropic etching by forming a film by a normal pressure CVD method or a plasma CVD method using tra-Ethyl-Ortho-Silicate, Si (OC ₂ H ₅ ) ₄ ) gas.

Next, the substrate temperature is set to 600 by the low pressure CVD method.
The temperature is set to be 0 ° C., and a polycrystalline silicon film having a film thickness of 200 nm to be the upper gate electrode 10 is formed. Then, a resist pattern is formed on the gate electrode formation portion of the driving TFT, and this polycrystalline silicon film is etched. By this,
As shown in FIG. 8, a gate electrode composed of the lower gate electrode 6a and the upper gate electrode 10 of the driving TFT is formed in the driving circuit portion, and the insulating film 5 of the displaying TFT is formed in the display portion.
The polycrystalline silicon film 6b formed on b is removed.

After that, as shown in FIG. 9, P (phosphorus), As (arsenic), and B (phosphorus), As (arsenic), and B are arranged so as to reach the semiconductor layer 4a of the driving TFT and the semiconductor layer 2 of the display TFT in a self-aligned manner.
Impurity ion implantation 11 such as (boron) is performed to form source regions 12a and 12b and drain regions 13a and 13b.
Are formed respectively. At this time, in the display TFT formed in the display portion, the sidewall insulator 8b serves as a mask during the ion implantation, and serves as the source region 12b and the drain region 13.
Between b and the channel portion 20b, portions 14 and 15 where a small amount of impurity ions are implanted or not implanted are formed.

Next, as shown in FIG. 10, after forming an interlayer insulating film 16 made of silicon oxide (SiO ₂ ) or silicon nitride (SiN _x ), a contact hole 17 is formed.
To form.

Further, as shown in FIG. 11, metal wiring 1
TFTs are completed by forming 8a and 18b.

In the above liquid crystal display panel,
The insulating film 3 is formed in the driving TFT portion formed in the driving circuit portion.
Serves as a base coat insulating film, so that the insulating property of the substrate 1 can be further improved. Since the semiconductor layer 4a and the gate insulating film 5a are continuously laminated and then the island pattern is formed, the interface state between the semiconductor layer 4a and the gate insulating film 5a can be made good. In addition, the semiconductor layer 4 can be formed without increasing the thickness of the gate insulating film.
The mobility can be improved by increasing the film thickness of a.
Since the sidewall insulator 8a is provided, the insulating property between the semiconductor layer 4a and the lower layer gate electrode 5a and the upper layer gate electrode 6a can be improved. Since the lower layer gate electrode 8a is laminated on the island-shaped pattern, and the lower layer gate electrode 6a is formed by patterning after forming the side wall insulator 8a, it is necessary to selectively etch the side wall insulator 8a. Absent. Further, since the lower layer gate electrode 6a and the upper layer gate electrode 10 are patterned and formed at the same time, the process can be simplified.

In the display TFT portion formed in the display portion, since the semiconductor layer 2 is formed separately from the semiconductor layer 4a of the driving TFT, the thickness of the semiconductor layer 2 can be reduced. Therefore, it is possible to prevent the insulating property of the gate insulating film 3 from being lowered in the step portion, and it is also possible to increase the resistance of the TFT and reduce the OFF current. Furthermore, since the sidewall insulator 8b is formed, when the impurity ions are implanted into the semiconductor layer 2 to form the source region and the drain region, the sidewall insulator 8b can be used as a mask to form the low-concentration impurity region. it can. Therefore, the OFF current of the TFT at the time of reverse gate bias can be reduced.

In this embodiment, the O of the display TFT is
The FF current could be reduced to 10 ⁻¹² A (ampere) or less, and the mobility of the driving TFT could be increased to 70 cm ² / Vs or more.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above embodiments and various modifications can be made.

For example, although the sidewall insulator is formed of SiO ₂ in the above embodiment, the present invention is not limited to this and may be formed of an insulator such as SiN _x . Although the gate electrode is formed using polycrystalline silicon, it may be formed using a metal such as Ti or W depending on manufacturing conditions. Alternatively, it can be formed in combination with silicide or the like.

Further, a liquid crystal display device can be manufactured by forming a liquid crystal alignment film on the entire surface of the substrate and enclosing a liquid crystal between the film and the counter substrate.

[0036]

As is apparent from the above description, according to the present invention, the interface state between the semiconductor layer and the gate insulating film should be good in the driving TFT portion formed in the driving circuit portion. Therefore, a gate insulating film having excellent insulating properties can be formed. Further, the mobility can be improved by increasing the thickness of the semiconductor layer without increasing the thickness of the gate insulating film. Therefore, high mobility required for the driving TFT can be realized. Further, in the display TFT portion formed in the display portion, the thickness of the semiconductor layer can be reduced, so that the TFT can have a high resistance and a low OFF current. Further, since the side wall insulator is formed on the side wall of the gate electrode, it is possible to form the impurity ion micro-implantation portion or the non-implantation portion in the semiconductor layer. Therefore, the OFF required for the display TFT
A reduction in current can be realized. Therefore, it is possible to obtain a driver monolithic active matrix substrate that can satisfy the device characteristics required for each, and it is possible to provide an active matrix liquid crystal display panel that can display a high-quality image.

[Brief description of drawings]

FIG. 1 is a diagram showing a TFT portion of an active matrix substrate which is an embodiment of the present invention, in which (a) is a driving TF.
A plan view of T is shown, and (b) is a plan view of a display TFT portion.

FIG. 2 is a diagram showing an example of a schematic configuration diagram of an active matrix substrate.

FIG. 3 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 4 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 5 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 6 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 7 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 8 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

FIG. 9 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, in which FIG.
1 is a sectional view taken along the line AA ′ in FIG. 1, (b) is a sectional view taken along the line BB ′ in FIG. 1 of the driving TFT, and (c) is a display TF.
The BB 'sectional view taken on the line in FIG. 1 of T is shown.

10A and 10B are diagrams showing a process of manufacturing an active matrix substrate of an example of the present invention, in which FIG. 10A is a sectional view of the driving TFT taken along the line AA ′ in FIG. 1, and FIG.
1 is a sectional view taken along the line BB ′ in FIG.
The BB 'sectional view taken on the line in FIG. 1 of FT is shown.

FIG. 11 is a diagram showing a manufacturing process of the active matrix substrate of the embodiment of the present invention, (a) is a sectional view of the driving TFT taken along the line AA ′ in FIG. 1, and (b) is a driving TFT.
1 is a sectional view taken along the line BB ′ in FIG.
The BB 'sectional view taken on the line in FIG. 1 of FT is shown.

[Explanation of reference numerals] 1 insulating substrate 2 semiconductor layer of display TFT 3 insulating film serving as gate insulating film of display TFT 4a semiconductor layer of driving TFT 4b gate electrode of display TFT 5a gate insulating film of driving TFT 6a Lower-layer gate electrode for driving TFT 10 Upper-layer gate electrode for driving TFT 14, 15 Trace-impregnated portion of impurity ion or non-implanted portion

Claims (2)

[Claims] 1. A display unit having display thin film transistors arranged in a matrix on an insulating substrate, and a driving unit for applying a signal to the display thin film transistor on a portion other than the display unit of the substrate. In an active matrix substrate on which a drive circuit section having thin film transistors is formed, both the display thin film transistor and the drive thin film transistor have an island-shaped semiconductor layer having a source / drain region on one side with a gate insulating film interposed therebetween. On the other hand, it has a gate electrode that partially overlaps with the semiconductor layer, and the semiconductor layer is arranged on the substrate side, and the gate electrode of the display thin film transistor and the semiconductor layer of the driving thin film transistor are It is formed of the same material, and the gate insulating film of the driving thin film transistor is the same as the driving semiconductor layer. Of is formed in an island-shaped pattern, further active matrix substrate sidewall insulators on the sidewalls of the semiconductor layer and the gate insulating film of the side walls and the thin film transistor for a gate electrode of the display thin film transistor are formed of the same material. 2. A display section having display thin film transistors arranged in a matrix is formed on an insulating substrate, and a driving section for applying a signal to the display thin film transistor on a portion other than the display section of the substrate. In a method of manufacturing an active matrix substrate having a drive circuit portion having thin film transistors, a step of forming a first semiconductor layer in an island pattern on a display thin film transistor forming portion on the substrate, and the first semiconductor layer. A step of forming a first insulating film so as to cover almost the entire surface of the substrate having the film formed thereon, and a step of laminating a second semiconductor layer and a second insulating film in this order on the first insulating film, A step of laminating a layer made of a semiconductor or a conductive material on the second insulating film; and patterning the second semiconductor layer, the second insulating film and the layer thereover to form a driving thin film transistor. A step of forming an island-shaped portion on the part where the island is formed, a linear portion that partially overlaps the first semiconductor layer on the display portion, and a sidewall is formed on each of the sidewall of the island-shaped portion and the sidewall of the linear portion. Forming a sidewall insulator covering the island, forming an upper gate electrode layer made of a semiconductor or a conductive material to cover the island formed with the sidewall insulator, and forming an upper gate of the island The electrode layer and the layer on the second insulating film are patterned to be linear, and the second portion of the linear portion is patterned.
The step of removing the layer above the insulating film, and the drive section performs ion implantation so that the ions reach the second semiconductor layer from the layer side for the upper gate electrode, and the display section displays the second layer. Ion implantation is performed so that the ions reach the first semiconductor layer from the insulating film side, the source / drain regions and the channel portion are formed in the second semiconductor layer of the driving unit, and the ion implantation is performed on the second insulating film of the driving unit. Layer and the layer for the upper gate electrode are used as the gate electrode of the driving thin film transistor, the source / drain region and the channel part are formed in the first semiconductor layer of the display portion, and the second semiconductor layer of the display portion is formed. A step of forming a gate electrode of a display thin film transistor, and a method for manufacturing an active matrix substrate, comprising: