JPH06138481A - Active matrix substrate and its production - Google Patents

Abstract

PURPOSE:To provide the driver monolithic type active matrix substrate with which the specifications required for TFTs for display driving picture elements and TFTs for driving a display part are compatible. CONSTITUTION:An active layer 106 of the TFTs for display driving the picture elements consists of a first p-Si film 104 and a second p-Si film 107. The active layer of the TFTs for driving the display part which drives scanning lines and the signal lines consist of only the second p-Si film 107. The film thickness of the p-Si film 106 of the TFTs for display is small, and therefore, the decreasing of off current is possible with the TFT for displaying. Since the film thickness of the p-Si film 107 is small with the TFTs for driving the display part, the increasing of on current is possible. The specifications required for the respective elements are thus made compatible.

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 in an active matrix drive type display device, and more particularly to a drive monolithic active matrix substrate.

[0002]

2. Description of the Related Art Conventionally, as a driving method of a display device such as a liquid crystal display device, an EL display device, a plasma display device, etc., a switching element is connected to each of pixel electrodes arranged in a matrix and selectively driven. There is known an active matrix driving method in which a display pattern is formed according to the above. This active matrix drive system is capable of high-contrast display, and has been put to practical use in, for example, liquid crystal televisions, word processors, and terminal display devices of computers. Further, as a switching element for selectively driving the pixel electrode, a TFT (thin film transistor) element, a MIM (metal-insulator-mim) element, an MO
S (metal-oxide-semiconductor) transistor element,
Diodes, varistors, etc. are commonly known.

An active matrix type display device has a display section in which a pixel electrode and a switching element for selectively driving the pixel electrode are formed, and a drive circuit for driving the display section. Conventionally, the drive circuit is provided by bonding an integrated circuit made of single crystal silicon or the like to an active matrix substrate on which a display unit is formed by a method such as tab bonding or COG (chip on glass) bonding. However, in recent years, active research has been conducted on a driver monolithic active matrix substrate in which a display section and a driving (driver) circuit are simultaneously formed on the same substrate. In a normal active matrix substrate, a large number of expensive driver LSIs are required, but in a driver monolithic active matrix substrate, the driver circuit is formed at the same time as the switching element formed in the display section, which reduces the cost of the display device. Can be achieved.
Further, since all peripheral functions are integrated in an area of only a few mm around the display unit, the entire module can be made compact and the mounting process can be simplified. The merits of this are great.

FIG. 5 shows a sectional view of a switching element portion in a conventional active matrix substrate using a polycrystalline silicon TFT as a switching element. In this figure, the right side shows the display section, and the left side shows the driver circuit section that drives the display section. In this active matrix substrate, a polycrystalline silicon (p-Si) film 502 having a source region 502a, a drain region 502b and an active region 502c is formed on a glass substrate 501 on which a base coat insulating film is formed, and thereon. A gate insulating film 503 made of a silicon oxide film or the like is formed so as to cover the entire surface of the substrate. Then, the scanning line (gate line) and the gate electrode 5 branched from the gate line
04 is formed, and the interlayer insulating film 505 is formed thereon. Further, the source electrode 506a branched from the signal line (source line) is formed, and the interlayer insulating film 505 is formed.
Source region 50 through the contact hole formed in
6a is electrically connected. In addition, a drain electrode 506b is formed in the driver circuit portion and is electrically connected to the drain region 506b via a contact hole formed in the interlayer insulating film 505. A pixel electrode 506c is formed in the display portion and is electrically connected to the drain region 506b through a contact hole formed in the interlayer insulating film 505. A passivation (oxide) film is formed on it to form an active matrix substrate.

Here, p-Si refers to those having various crystal orientations in the same film.

[0006]

By the way, in order to realize a display device using a driver monolithic active matrix substrate, a switching element for driving a display section formed in a driver circuit is required to have high mobility. It On the other hand, the display switching element formed in the display unit is not required to have such high mobility. However, the display switching element has a large ON / OF
The F current ratio is required, and particularly the OFF current is required to be small. Therefore, different specifications are required for the display unit driving switching element and the display switching element which are simultaneously formed on the same substrate. In the past, it was difficult to satisfy these different specifications at the same time.

For example, as can be understood from FIG. 5, the structural difference between the switching element of the driver circuit section and the switching element of the display section is that the drain electrode in the driver circuit serves as a pixel electrode in the display section. And there is no other big difference. However, as mentioned above,
The element characteristics required for the switching element of the driver circuit and the switching element of the display section are different. In the past, the element characteristics were controlled by making the two-dimensional element size different. Therefore, a large area may be required on the substrate, and conversely, it may be necessary to form a small area less than the patterning accuracy, which causes a problem.

The present invention has been made in order to solve the above-mentioned problems, and simultaneously satisfies the specifications required for a display switching element for driving pixels and the specifications required for a display section driving switching element. It is to obtain a compatible driver monolithic active matrix substrate.

[0009]

The active matrix substrate of the present invention comprises a matrix of pixel electrodes and display switching elements each having an active layer which is in a conducting or non-conducting state. A plurality of display portions each having a display portion, a drive circuit portion for driving the display portion formed on a substrate portion other than the display portion, and an active layer for making the drive circuit portion conductive or non-conductive. In the active matrix substrate having the driving switching element, the thickness of the active layer of the display switching element is different from the thickness of the active layer of the display driving switching element, thereby achieving the above object.

According to the method of manufacturing an active matrix substrate of the present invention, a display section is formed on the substrate, in which pixel electrodes and display switching elements each having an active layer which is conductive or non-conductive are formed in a matrix. A plurality of switching circuits for driving a display unit, which has a drive circuit unit that drives the display unit on a substrate portion other than the display unit and includes an active layer that makes the drive circuit unit conductive or non-conductive. In a method of manufacturing an active matrix substrate having elements, a step of forming a first active layer in a portion where an active layer of the display section driving switching element is formed, the display section driving switching element and the display switching Forming a second active layer in a portion of the device where the active layer is formed, thereby achieving the above object.

According to the method of manufacturing an active matrix substrate of the present invention, a display portion is formed on the substrate, in which pixel electrodes and display switching elements each having an active layer which is in a conductive or non-conductive state are formed in a matrix. A plurality of display units for driving the display unit, the drive circuit unit driving the display unit is formed on a substrate portion other than the display unit, and the drive circuit unit includes an active layer that is a conductive or non-conductive normal body. A method for manufacturing an active matrix substrate having a switching element includes a step of forming an active layer of each switching element, and a step of etching the active layer of the display switching element to reduce its thickness. The purpose is achieved.

The display switching element and the display section driving switching element may be thin film transistors, and the active layer may be made of polycrystalline silicon.

The active matrix substrate of the present invention has a plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, and pixel electrodes formed in the vicinity of intersections of the scanning lines and the signal lines on the substrate. And a display portion having a display thin film transistor connected to the pixel electrode, and a drive circuit portion for driving the display portion is formed on a substrate portion other than the display portion. In the active matrix substrate having the display part driving thin film transistor, the thickness of the gate insulating film of the display part driving thin film transistor is different from the thickness of the gate insulating film of the display part driving thin film transistor, thereby achieving the above object.

According to the method of manufacturing an active matrix substrate of the present invention, a plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, and a portion near the intersections of the scanning lines and the signal lines are formed on the substrate. A pixel electrode and a display thin film transistor connected to the pixel electrode, and a drive circuit portion for driving the display portion is formed on a substrate portion other than the display portion. A method of manufacturing an active matrix substrate having a plurality of display-driving thin film transistors, the step of forming a first gate insulating film in a portion of the display-driving thin film transistor where the gate insulating film is formed; A step of forming a second gate insulating film in a portion of the driving thin film transistor and the display thin film transistor where the gate insulating film is formed, and thereby, There is achieved.

According to the method of manufacturing an active matrix substrate of the present invention, a plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, and a portion near the intersection of the scanning lines and the signal lines are formed on the substrate. A pixel electrode and a display thin film transistor connected to the pixel electrode, and a drive circuit portion for driving the display portion is formed on a substrate portion other than the display portion. A method of manufacturing an active matrix substrate having a plurality of display portion driving thin film transistors, a step of forming a gate insulating film of each thin film transistor, and a step of etching the gate insulating film of the display thin film transistor to reduce the thickness, The above object is achieved thereby.

[0016]

In the active matrix substrate of the present invention, the thickness of the active layer of the display switching element for driving the pixel is different from the thickness of the active layer of the display section driving switching element, or the gate insulation of the display TFT is performed. The thickness of the film and the thickness of the gate insulating film of the display driving TFT are different.

In the switching element, the ON / OFF current can be adjusted by changing the thickness of the active layer. For example, as a switching element, p-Si
When a TFT is used, the OFF current can be reduced by reducing the thickness of the p-Si film that is the active layer, and the ON current can be increased by increasing the thickness of the p-Si film. be able to. Therefore, a thin p-Si film is formed as an active layer of the display switching element,
By forming a thick p-Si film as an active layer of the display unit driving switching element, it is possible to satisfy the specifications required for each element.

Further, in the TFT, by increasing the film thickness of the gate insulating film, the voltage applied to the channel can be suppressed to reduce the OFF current, and by decreasing the film thickness of the gate insulating film, the ON current can be reduced. Can be large. Therefore, a thick insulating film is formed as the gate insulating film of the display switching element, and a thin insulating film is formed as the gate insulating film of the display driving switching element. It is possible to satisfy both specifications.

As a result, the specifications required for each of the display switching element and the display section driving switching element can be made compatible without greatly changing the two-dimensional size.

[0020]

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

(Embodiment 1) FIG. 1F shows a sectional view of a switching element formed in a driver circuit portion and a display portion in an active matrix substrate of Embodiment 1. In this active matrix substrate, a display portion and a driver circuit portion are formed on a glass substrate 101. Scanning lines and signal lines are formed in the display portion, pixel electrodes are formed at the intersections thereof, and p-SiTFTs are formed as switching elements connected to the pixel electrodes. Further, a p-Si TFT is also formed in the driver circuit section. In the active matrix substrate of this embodiment, the display section driving TF formed in the driver circuit section is formed.
The thickness of the active layer 106 of T and the display T formed in the display portion.
It is different from the film thickness of the active layer 107 of FT.

This active matrix substrate is shown in FIG.
It is manufactured according to the manufacturing process as shown in (a) to (f). In this figure, the left side shows the display portion driving TFT portion formed in the driver circuit portion, and the right side shows the display TFT portion formed in the display portion, which are formed simultaneously on the same substrate. .

First, as shown in FIG. 1A, for example, plasma C is placed on a transparent glass substrate 101 which has been washed in advance.
Substrate temperature 300 ° C by VD (chemical vapor deposition) method
Base coat insulating film 1 made of silicon oxide (SiO ₂ ) having a film thickness of about 1000 Å
02 is formed. By forming this insulating film 102, contamination from the substrate 101 can be prevented. Next, a film thickness of 150 is formed on the entire surface of the substrate by, for example, a low pressure (LP) CVD method at a substrate temperature of about 550 ° C.
Amorphous silicon (a-Si) of about 0 angstrom
The film 103 is formed.

Next, as shown in FIG. 1B, a-Si
The film 103 is etched to form an island-shaped pattern only in the driver circuit portion to form an a-Si film 104a. The a-Si film 104a is a film that will become the first active layer 104 in a later step.

Thereafter, as shown in FIG. 1C, the substrate temperature is set to 50 on the entire surface of the substrate by, for example, the LPCVD method.
A- with a film thickness of about 300 Å at about 0 ° C
The Si film 105 is formed.

Then, as shown in FIG. 1D, aS
The i film 105 is etched to form an island pattern on both the driver circuit portion and the display portion, and the a-Si film 107 is formed.
a. The a-Si film 107a is a film that will become the second active layer 107 in a later step. By this,
The a-Si film 104a and the a-Si film 1 are provided in the driver circuit section.
07a and an a-Si film 106a having a thickness of about 1800 angstroms is formed, and the display portion has a thickness of 300
Only the a-Si film 107a having a thickness of about angstrom is formed.

Then, for example, by performing solid layer growth annealing at a substrate temperature of about 600 ° C. for about 36 hours in a nitrogen atmosphere, the a-Si films 106a and 107a are crystallized to form p-Si films.

Next, as shown in FIG. 1E, a gate made of SiO ₂ having a film thickness of about 1500 angstroms is formed on the entire surface of the substrate by, for example, AP (normal thickness) CVD method at a substrate temperature of about 300 ° C. The insulating film 108 is formed.
Then, for example, by setting the substrate temperature to about 600 ° C., the LPC
An impurity-doped p-Si film is formed to a thickness of about 2000 angstroms by the VD method or the like, and is patterned into a predetermined shape by etching to form a gate line and a gate electrode 109 branched from the gate line. In the above, a metal thin film formed by a sputtering method may be used instead of the p-Si film doped with impurities. Then, on the p-Si films 106 and 107,
For example, phosphorus 110 is ion-implanted to accelerate voltage 8
Doping is performed under the conditions of 0 keV and an impurity density of 5 × 10 ¹⁵ cm ^-2 . As a result, the source regions 113 and 115 and the drain regions 114 and 116 made of ion-doped p-Si are formed as shown in FIG. At this time, due to the shielding effect of the gate electrode 109, the active regions 111 and 112 of the TFT are not doped with impurities.

Subsequently, for example, active annealing is performed at a substrate temperature of about 600 ° C. for about 6 hours, so that the source regions 113 and 115 and the drain regions 114 and 11 are formed.
Activate 6 As a result, the active layer 106 including the first active layer 107 and the second active layer 104 is formed in the driver circuit section, and the second active layer 10 is formed in the display section.
An active layer consisting of only 7 is formed, and, for example,
An interlayer insulating film 117 made of SiO ₂ and having a film thickness of about 4000 angstroms is formed by the APCVD method so as to cover the gate electrode 109 at a substrate temperature of about 300 ° C.

Next, predetermined portions of the gate insulating film 108 and the interlayer insulating film 117 are removed to remove the source regions 113, 1
Contact holes are formed so as to reach 15 and the drain regions 114 and 116. Then, a transparent conductive film made of ITO or the like is vapor-deposited to have a thickness of about 1000 Å by a sputtering method, and patterned into a predetermined shape by etching to form a pixel electrode 121. Next, aluminum is vapor-deposited by a sputtering method, patterned into a predetermined shape by etching, and a source line 120 and a source electrode 118 branched from the source line 120 are formed.
And the drain electrode 119 is formed. Here, the source electrode 118 and the source line 120 are respectively the source region 1
The drain electrode 119 and the pixel electrode 121 are connected to the drain regions 114 and 116, respectively.

After that, a passivation film 122 made of a nitride film is deposited by plasma CVD at a substrate temperature of about 250 ° C., and then patterned into a predetermined shape by etching to form the pixel electrode 121.
Expose. The insulating film 122 can prevent contamination from the external environment. As a result, an active matrix substrate is formed. Furthermore, the active region 11
In order to improve the characteristics of the interface between the gate insulating film 108 and the gate insulating film 108 and to improve the grain boundary characteristics of the silicon microcrystals forming the p-Si in the active regions 111 and 112, for example, hydrogen is included. The hydrogen plasma treatment using gas may be performed at a substrate temperature of about 300 ° C.

As described above, the active matrix substrate in which the active layer 106 and the active layer 107 have different film thicknesses can be obtained between the display portion driving TFT formed in the driver circuit portion and the display TFT formed in the display portion. .

In this embodiment, the O of the display TFT is
The FF current could be reduced to 10 ^-10 Å or less, and the ON current of the display driving TFT could be increased to 10 ^-4 Å or more.

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 the liquid crystal with the counter substrate.

(Embodiment 2) FIG. 2E shows a sectional view of a TFT formed in a driver circuit portion and a display portion in an active matrix substrate of Embodiment 2. In this active matrix substrate, a display portion and a driver circuit portion are formed on a glass substrate 201. Scanning lines and signal lines are formed in the display portion, pixel electrodes are formed at the intersections thereof, and p-SiTFTs are formed as switching elements connected to the pixel electrodes. Further, a p-Si TFT is also formed in the driver circuit section. In the active matrix substrate of this embodiment, similar to the first embodiment, the film thickness of the active layer 204 of the display portion driving TFT formed in the driver circuit portion and the active layer 207 of the display TFT formed in the display portion 207. It is different from the film thickness of.

This active matrix substrate is shown in FIG.
It is manufactured according to the manufacturing process as shown in (a) to (e). In this figure, the left side shows the display portion driving TFT portion formed in the driver circuit portion, and the right side shows the display TFT portion formed in the display portion, which are formed simultaneously on the same substrate. .

First, as shown in FIG. 2A, the base coat insulating film 2 was formed on the glass substrate 201 in the same manner as in Example 1.
02 is formed. Then, the a-Si film 2 having a film thickness of about 1500 angstrom is formed on the entire surface of the substrate in the same manner as in the first embodiment.
Form 03.

Next, as shown in FIG. 2B, a-Si
The film 203 is etched to form island patterns in the driver circuit portion and the display portion to form a-Si films 204a and 205.

After that, as shown in FIG. 2C, a photoresist is applied to the substrate and exposed to cover the island-shaped a-Si film 204a in the driver circuit portion so that the resist is formed. The pattern 206 is formed. By controlling etching the substrate in this state,
A- of the display part not covered with the resist pattern 206
The Si film 205 has a film thickness of about 300 Å, as shown in FIG. In this etching step, it is necessary to check the etching rate of a-Si with respect to the etchant in advance. Then, the resist pattern 206 is removed. As a result, the driver circuit section has an aS of about 1500 angstroms.
The i film 204a is formed, and the a-Si film 207a having a thickness of about 300 Å is formed on the display portion. The a-Si films 204a and 207a are films that will become the active layer 204 of the display TFT and the active layer 207 of the display driving TFT, respectively, in the subsequent steps.

Then, as in the first embodiment, as shown in FIG.
An active matrix substrate as shown in (e) is manufactured.

As described above, an active matrix substrate in which the active layers 204 and 207 have different film thicknesses can be obtained in the display portion driving TFT formed in the driver circuit portion and the display TFT formed in the display portion. .

In this embodiment, the O of the display TFT is
The FF current could be reduced to 10 ^-10 Å or less, and the ON current of the display driving TFT could be increased to 10 ^-4 Å or more.

(Embodiment 3) FIG. 3F shows a sectional view of a TFT formed in a driver circuit portion and a display portion in an active matrix substrate of Embodiment 3. In this active matrix substrate, a display portion and a driver circuit portion are formed on a glass substrate 301. Scanning lines and signal lines are formed in the display portion, pixel electrodes are formed at the intersections thereof, and p-SiTFTs are formed as switching elements connected to the pixel electrodes. Further, a p-Si TFT is also formed in the driver circuit section. In the active matrix substrate of this embodiment, the film thickness of the gate insulating film 319 of the display part driving TFT formed in the driver circuit part and the film thickness of the gate insulating film 320 of the display TFT formed in the display part. Is different.

This active matrix substrate is shown in FIG.
It is manufactured according to the manufacturing process as shown in (a) to (f). In this figure, the left side shows the display portion driving TFT portion formed in the driver circuit portion, and the right side shows the display TFT portion formed in the display portion, which are formed simultaneously on the same substrate. .

First, as shown in FIG. 3A, the base coat insulating film 3 was formed on the glass substrate 301 in the same manner as in Example 1.
02 is formed. Then, an a-Si film having a film thickness of about 1000 Å is formed on the entire surface of the substrate by, for example, a low pressure (LP) CVD method at a substrate temperature of about 550 ° C., and the a-Si film is etched to form a driver circuit portion. And an island pattern is formed on the display part to
-Si film 303. Then, in the same manner as in Example 1, the a-Si film 303 is crystallized to form the p-Si film 303.

Next, as shown in FIG. 3B, the island-shaped p-Si film 303 is covered, and, for example,
A SiO ₂ film 304 having a film thickness of about 1000 angstroms is formed at a substrate temperature of about 300 ° C. by the APCVD method or the like.
To form. The SiO ₂ film 304 is a film that will become the first gate insulating film 318 in a later step.

Then, as shown in FIG. 3C, the SiO ₂ film 304 formed in the driver circuit portion is removed by etching.

Next, as shown in FIG. 3 (d), the whole substrate is covered, for example, by the APCVD method.
At a substrate temperature of about 300 ° C., a SiO ₂ film 305 having a film thickness of about 1000 Å is formed. The SiO ₂ film 305 is a film that will become the second gate insulating film 319 in a later step.

Then, as shown in FIG. 3E, the p-Si film doped with impurities was formed into a film having a thickness of 2 as in the first embodiment.
The gate electrode 3 and the gate electrode 3 branched from the gate line are formed by etching and patterned into a predetermined shape.
06 is formed. Next, the SiO ₂ films 304 and 305 are etched using the gate electrode 306 as a mask to remove the portions other than below the gate electrode 306 to remove SiO 2.
_Two films 318 and 319. As a result, the first gate insulating film 318 and the second gate insulating film 319 are formed on the display portion.
A gate insulating film 320 having a thickness of 2000 angstroms is formed, and a gate insulating film having only a second gate insulating film 319 having a thickness of 1000 angstroms is formed in the driver circuit portion. In this etching process, Si formed in the display section and the driver circuit section
Since the thickness of the O ₂ film is different, the etchant needs to have sufficient selectivity with respect to the p-Si film forming the gate insulating film. Examples of such an etchant include buffered hydrofluoric acid.

Then, for example, phosphorus 307 is ion-implanted into the p-Si film 303 to accelerate it to an acceleration voltage of 10 keV.
Doping is performed under conditions such as an impurity density of 5 × 10 ¹⁵ cm ⁻² . This results in ion-doped p-Si
Source regions 308 and 310 and drain regions 309 and 311 are formed. In this ion implantation process, for example, if the acceleration voltage is 10 keV, the impurity density can be 5 × 10 ¹⁵ cm ⁻² .

Then, similarly to the first embodiment, the source regions 308 and 310 and the drain regions 309 and 311 are activated.

Next, as shown in FIG.
Interlayer insulating film 3 made of SiO _{2 of} about angstrom
12 is formed in the same manner as in Example 1 so as to cover the substrate. Then, a predetermined portion of the interlayer insulating film 312 is removed to remove the source regions 308 and 310 and the drain region 30.
Contact holes are formed to reach 9 and 311. Then, similarly to Embodiment 1, the pixel electrode 316, the source line 315, the source electrode 313 branched from the source line, and the drain electrode 314 are formed. Here, the source electrode 313 and the source line 315 are connected to the source regions 308 and 310, respectively, and the drain electrode 31
4 and the pixel electrode 316 are drain regions 309 and 31 respectively.
Connected to 1. Then, in the same manner as in Example 1,
A passivation film 317 made of a nitride film is formed to be an active matrix substrate. Further, if necessary, for example, hydrogen plasma treatment using a gas containing hydrogen may be performed at a substrate temperature of about 300 ° C.

As described above, an active matrix substrate in which the gate insulating films 319 and 320 have different film thicknesses in the display portion driving TFT formed in the driver circuit portion and the display TFT formed in the display portion is obtained. To be

In this embodiment, the O of the display TFT is
The FF current could be reduced to 10 ^-10 Å or less, and the ON current of the display driving TFT could be increased to 10 ^-4 Å or more.

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

(Embodiment 4) FIG. 4E shows a sectional view of a TFT formed in a driver circuit portion and a display portion in an active matrix substrate of Embodiment 4. In this active matrix substrate, a display portion and a driver circuit portion are formed on a glass substrate 401. Scanning lines and signal lines are formed in the display portion, pixel electrodes are formed at the intersections thereof, and p-SiTFTs are formed as switching elements connected to the pixel electrodes. Further, a p-Si TFT is also formed in the driver circuit section. In the active matrix substrate of this embodiment, the film thickness of the gate insulating film 407 of the display part driving TFT formed in the driver circuit part and the film thickness of the gate insulating film 408 of the display TFT formed in the display part. Is different.

This active matrix substrate is shown in FIG.
It is manufactured according to the manufacturing process as shown in (a) to (e). In this figure, the left side shows the display portion driving TFT portion formed in the driver circuit portion, and the right side shows the display TFT portion formed in the display portion, which are formed simultaneously on the same substrate. .

First, as shown in FIG. 4A, the base coat insulating film 4 was formed on the glass substrate 401 in the same manner as in Example 3.
02 and p-Si film 403 are formed.

Next, as shown in FIG. 4B, the p-Si film 403 formed in an island shape is covered, and, for example,
A SiO ₂ film 404 having a film thickness of about 2000 angstroms is formed by the APCVD method or the like at a substrate temperature of about 300 ° C.
To form.

Then, as shown in FIG. 4C, a photoresist is applied to the substrate and exposed to expose the resist pattern 405 so as to cover the SiO ₂ film 404 formed in the island shape in the display portion. To form. By subjecting the substrate in this state to control etching, the portion of the SiO ₂ film 40 not covered with the resist pattern 405 is etched.
4 has a film thickness of about 1000 Å, as shown in FIG. In this etching step, it is necessary to check the etching rate of the gate insulating film material with respect to the etchant in advance. Then, the resist pattern 405 is removed. As a result, the driver circuit section has an S of about 1000 angstroms.
An iO ₂ film 406 is formed, and a SiO ₂ film 404 having a thickness of about 2000 Å is left in the display portion. The SiO ₂ films 406 and 404 will be used as a gate insulating film 408 of a display TFT and a display portion driving T in a later step.
It is used as the gate insulating film 407 of the FT.

After that, as in the third embodiment, as shown in FIG.
An active matrix substrate as shown in (e) is manufactured.

As described above, the active matrix substrate in which the gate insulating films 407 and 408 are different in film thickness between the display portion driving TFT formed in the driver circuit portion and the display TFT formed in the display portion is obtained. To be

In this embodiment, the O of the display TFT is
The FF current could be reduced to 10 ^-10 Å or less, and the ON current of the display driving TFT could be increased to 10 ^-4 Å or more.

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

For example, in the above, Si serving as an active layer
By forming the jig of the film forming device or the SiO ₂ film forming device to be the gate insulating film, the film thickness formed at the edge of the substrate and the film thickness at the center of the substrate are made different. You can also do it.

Also, by combining the first or second embodiment with the third or fourth embodiment, both the film thickness of the active layer and the film thickness of the gate insulating film are controlled, and the driver circuit is further enhanced. The element characteristics required for the display section and the display section can be compatible with each other.

Although p-SiTFTs are used as switching elements in the above embodiments, the present invention is not limited to this. For example, a-SiTFTs, MIM elements, MOS transistor elements, diodes, varistors, etc. may be used. .

[0068]

As is apparent from the above description, according to the present invention, in the driver monolithic type active matrix substrate, each of the switching elements formed in the driver circuit section and the switching elements formed in the display section is required. It is possible to satisfy the required device characteristics without changing the device size. Therefore, in the driver circuit portion, the area of the switching element occupying the substrate is reduced, and the space can be saved. In addition, in the display unit, it is possible to prevent a decrease in yield due to the size reduction of the switching element. Therefore, an active matrix display device capable of obtaining a high quality image can be obtained at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a manufacturing process of an active matrix substrate according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing process of the active matrix substrate according to the second embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing process of the active matrix substrate according to the third embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing process of the active matrix substrate according to the fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a TFT portion of a conventional active matrix substrate.

[Explanation of symbols]

 101, 201, 301, 404 Substrate 106, 107, 204, 207 Active layer 319, 320, 407, 408 Gate insulating film

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Tsukasa Shibuya 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka Within Sharp Co., Ltd. Within the corporation

Claims (7)

[Claims] 1. A display part, which is formed by forming pixel electrodes and display switching elements each having an active layer in a conductive or non-conductive state in a matrix on a substrate, and a substrate other than the display part. An active matrix substrate having a plurality of switching elements for driving a display unit, wherein a drive circuit unit for driving the display unit is formed on the portion, and the drive circuit unit includes a plurality of switching elements for driving the display unit, the active layer being in a conductive or non-conductive state. An active matrix substrate in which the thickness of the active layer of the display switching element is different from the thickness of the active layer of the display section driving switching element. 2. A display portion is formed on a substrate, in which pixel electrodes and a display switching element having an active layer that is in a conductive or non-conductive state are formed in a matrix, and a substrate other than the display portion. A method of manufacturing an active matrix substrate having a plurality of switching elements for driving a display unit, the drive circuit unit driving the display unit is formed on the portion, and the drive circuit unit is provided with an active layer that is conductive or non-conductive. In the step of forming a first active layer in a portion where the active layer of the display portion driving switching element is formed, and a portion where the display portion driving switching element and the active layer of the display switching element are formed. And a step of forming a second active layer on the substrate. 3. A display portion, which is formed by forming a matrix of pixel electrodes and a display switching element having an active layer in a conductive or non-conductive state on a substrate, and a substrate other than the display portion. Manufacture of an active matrix substrate having a plurality of switching elements for driving a display unit, in which a drive circuit unit for driving the display unit is formed on a portion, and the drive circuit unit is provided with an active layer that is a conductive or non-conductive normal body. A method of manufacturing an active matrix substrate, comprising: a method of forming an active layer of each switching element; and a step of etching the active layer of the display switching element to reduce the thickness. 4. The active matrix substrate according to claim 1, wherein the display switching element and the display section driving switching element are thin film transistors, and the active layer is made of polycrystalline silicon. 5. A plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, a pixel electrode formed in the vicinity of an intersection of the scanning line and the signal line, and a pixel electrode on the substrate. A display portion having a connected display thin film transistor is formed,
In an active matrix substrate in which a drive circuit unit for driving the display unit is formed on a substrate portion other than the display unit, and the drive circuit unit has a plurality of display unit driving thin film transistors, the gate insulation of the display thin film transistor is provided. An active matrix substrate having a film thickness different from that of a gate insulating film of the display portion driving thin film transistor. 6. A plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, a pixel electrode formed in the vicinity of an intersection of the scanning line and the signal line, and a pixel electrode on the substrate. A display portion having a connected display thin film transistor is formed,
In a method of manufacturing an active matrix substrate, wherein a drive circuit section for driving the display section is formed on a substrate section other than the display section, and the drive circuit section has a plurality of display section driving thin film transistors, A step of forming a first gate insulating film in a portion of the thin film transistor where the gate insulating film is formed; and a second gate insulating film in a portion of the display portion driving thin film transistor and the display thin film transistor where the gate insulating film is formed. And a step of forming an active matrix substrate. 7. A plurality of scanning lines, a plurality of signal lines intersecting the scanning lines, a pixel electrode formed in the vicinity of an intersection of the scanning line and the signal line, and a pixel electrode on the substrate. A display portion having a connected display thin film transistor is formed,
In a method of manufacturing an active matrix substrate in which a drive circuit unit for driving the display unit is formed on a substrate portion other than the display unit, and the drive circuit unit has a plurality of display unit driving thin film transistors, gate insulation of each thin film transistor is provided. A method of manufacturing an active matrix substrate, comprising: a step of forming a film; and a step of etching the gate insulating film of the display thin film transistor to reduce its thickness.