JP2001209070A - Liquid crystal display device - Google Patents

Abstract

(57) [Problem] To substantially increase a channel width of a TFT without increasing a capacitance between a gate and a source electrode of the TFT.
A large current can be supplied to the TFT, a driving duty is increased, and a high pixel density is achieved. In addition, an opening ratio is sufficiently increased by eliminating the need to increase a wiring width of a gate wiring. Provided is an active matrix liquid crystal display element capable of performing favorable display by reducing a change in a writing state of a pixel region due to an influence of an inter-capacitance. SOLUTION: A TFT 13 is provided with at least the source electrode 17 out of a source electrode 17 and a drain electrode 17 thereof.
However, the TFT 13 has a configuration in which a notch 17a is formed at the edge of the TFT 13 on the channel region side so as to be recessed from the edge toward the inside of the electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active matrix type liquid crystal display device using thin film transistors (hereinafter, referred to as TFTs) as switching elements.

[0002]

2. Description of the Related Art As an active matrix type liquid crystal display device, a device using a TFT as an active device is widely used.

This active matrix liquid crystal display element has a plurality of pixel electrodes and a plurality of TFTs arranged in a matrix on an inner surface of one of a pair of substrates arranged opposite to each other (hereinafter referred to as a TFT substrate). , A plurality of gate wirings and data wirings are provided, a counter electrode facing the plurality of pixel electrodes is provided on an inner surface of the other substrate (hereinafter, referred to as a counter substrate), and liquid crystal is sealed between the pair of substrates. It is the configuration that was done.

FIG. 5 is a plan view of a part of a TFT substrate of a conventional active matrix liquid crystal display device.
A plurality of transparent pixel electrodes 2 arranged in a matrix in the row direction and the column direction on the inner surface of the FT substrate 1, and are arranged corresponding to these pixel electrodes 2, and a source electrode 7 is provided on the corresponding pixel electrode 2. A plurality of connected TFTs 3,
A plurality of gate lines 9 for supplying gate signals to the gate electrodes 4 of the TFTs 3 in each row and a plurality of data lines 10 for supplying data signals to the drain electrodes 8 of the TFTs 3 in each column are provided.

The TFT 3 includes a gate electrode 4 formed on the substrate 1 and a gate insulating film 5 covering the gate electrode 4.
An i-type semiconductor film 6 provided on the gate insulating film 5 so as to face the gate electrode 4; and a source electrode 7 and a drain electrode 8 provided on both sides of the i-type semiconductor film 6. The source electrode 7 and the drain electrode 8 are respectively formed of n and n for forming a source region and a drain region formed on the i-type semiconductor film 6.
And a conductive metal film formed on the n-type semiconductor film.

Amorphous silicon or polysilicon is used for the i-type semiconductor film 6 of the TFT 3 and the n-type semiconductor film which is a lower layer film of the source electrode 7 and the drain electrode 8. Although the mobility of electrons is lower than that of single crystal silicon, it can be formed relatively easily on the substrate 1 made of glass or the like, and thus is suitable for a switching TFT of a liquid crystal display element.

The gate wiring 9 is formed integrally with the gate electrode 4 of the TFT 3 on the substrate 1, and the data wiring 10 is formed on the gate insulating film 5 to form a drain electrode of the TFT 3. Connected to 8.

The pixel electrode 2 is formed on the gate insulating film 5, and a source electrode 8 of the TFT 3 corresponding to the pixel electrode 2 is provided on a side edge of the pixel electrode 2.
Is connected.

In this active matrix liquid crystal display element, a gate signal having a waveform in which a period during which the potential for turning on the TFT 3 is turned on is sequentially supplied to the plurality of gate lines 9, and the plurality of data lines 10 are supplied to the plurality of data lines 10. The display is driven by supplying a data signal having a waveform whose potential changes in accordance with image data in each selection period of the gate wiring 9. The gate wiring 9 corresponds to each selection period of the gate wiring 9. A data signal is applied from the data wiring 10 to the pixel electrode 2 of the row to be connected via the TFT 3, and a write charge corresponding to the potential of the data signal is applied to the pixel electrode 3 and a counter electrode provided on a counter substrate (not shown). The pixel capacitor composed of the liquid crystal layer therebetween is charged, and writing is performed in a plurality of pixel regions where the plurality of pixel electrodes 2 and the counter electrode face each other. Divide.

[0010]

By the way, active matrix liquid crystal display elements tend to have higher and higher pixel densities, and therefore, it is required to perform time-division driving with a higher duty.

On the other hand, in the active matrix liquid crystal display element, the i-type semiconductor film 6 of the switching TFT 3 and the n-type semiconductor film which is the lower layer of the source electrode 7 and the drain electrode 8 have a smaller number of electrons than single crystal silicon. Since it is made of amorphous silicon or polysilicon having low mobility, a sufficient amount of write charge corresponding to the potential of the data signal supplied from the data line 10 within the limited selection period (the ON period of the TFT 3) is sufficient for the pixel capacitance. In order to charge the TFT, the channel length of the TFT 3 (the source electrode 7
The distance L between the opposing edges of the drain electrode 8 and the drain electrode 8) is made as small as possible, the channel width (the width of the source electrode 7 and the drain electrode 8) W is made as large as possible, and T
It is necessary to allow a large current to flow through FT3.

However, in order to maintain the write charge charged to the pixel capacitor during the selection period until the next selection period, the source electrode 7 and the drain electrode 8 of the TFT 3 are connected so that no leakage current occurs between them. Therefore, there is a limit to reducing the channel length L.

When the width of the source electrode 7 and the drain electrode 8 of the TFT 3 is increased and the channel width W thereof is increased to allow a large current to flow through the TFT 3,
The TFT 3 having a large channel width W has a stray capacitance between the gate electrode 4 and the source electrode 7 (hereinafter, referred to as a gate-source electrode capacitance) and a stray capacitance between the gate electrode 4 and the drain electrode 8 (hereinafter, referred to as a capacitance). (Referred to as the gate-drain electrode capacitance), the effect of the gate-source electrode capacitance and the gate-drain electrode capacitance,
Due to the influence of the capacitance between the source electrodes, the waveform of the gate signal supplied from the gate wiring 9 to the gate electrode 4 becomes blunt,
The TFT 3 cannot be turned on / off with good operability, and writing characteristics to the pixel region deteriorate.

The dullness of the waveform of the gate signal can be compensated to some extent by lowering the electric resistance of the gate wiring 9, but in order to reduce the resistance of the gate wiring 9, the wiring width must be widened. Therefore, the aperture ratio of the liquid crystal display element decreases.

In addition, the capacitance between the gate and source electrodes of the TFT 3 also affects the write charge charged to the pixel capacitance composed of the pixel electrode 3 and a counter electrode provided on a counter substrate (not shown) and a liquid crystal layer therebetween. Therefore, if the capacitance between the gate and source electrodes is large, the writing state of the pixel region changes.

For these reasons, it is conventionally difficult to increase the channel width W of the TFT 3 to allow a large current to flow. Therefore, it is necessary to increase the drive duty of the active matrix liquid crystal display element. It was difficult to increase the pixel density.

According to the present invention, a large current can be supplied to the TFT without increasing the capacitance between the gate and source electrodes of the TFT, a large current can be supplied to the TFT, and the driving duty is increased to increase the pixel count. In addition to increasing the density, it is not necessary to increase the wiring width of the gate wiring, so that the aperture ratio is sufficiently increased. It is an object of the present invention to provide an active matrix type liquid crystal display element capable of performing display.

[0018]

According to the present invention, a plurality of pixel electrodes arranged in a matrix in a row direction and a column direction on an inner surface of one of a pair of substrates arranged opposite to each other are provided. It is arranged corresponding to each electrode,
A plurality of TFTs each having a source electrode connected to the corresponding pixel electrode, a plurality of gate lines for supplying gate signals to the gate electrodes of the TFTs in each row, and a data signal to each drain electrode of the TFTs in each column. A plurality of data wirings are provided, and on the inner surface of the other substrate, a counter electrode facing the plurality of pixel electrodes is provided, and in an active matrix liquid crystal display element in which liquid crystal is sealed between the pair of substrates, Of the source electrode and the drain electrode of the TFT, at least the source electrode is
An edge of the FT on the channel region side is formed in a shape having a cutout recessed from the edge toward the inside of the electrode.

The liquid crystal display device according to the present invention is characterized in that
Out of the source electrode and the drain electrode, at least the source electrode was formed in a shape provided with a cutout recessed in the electrode inward direction from the edge on the channel region side edge of the TFT. TF
The current path between the source electrode and the drain electrode when T is turned on is not only between the edge of the portion of the source electrode without the notch and the drain electrode, but also the current path of the source electrode. It is also formed between the side edge of the notch and the drain electrode.

Therefore, the TFT has a channel width substantially larger than an apparent channel width in which the edge of the portion of the source electrode without the notch and the edge of the drain electrode face each other. I have.

In this TFT, since the source electrode is formed in a shape in which the notch is provided at the edge on the channel region side, a substantial channel width is reduced between the source electrode and the drain electrode. Even if the edge on the channel region side is the same as the channel width of a general TFT having a straight edge without the notch, the general TFT
In this case, the facing area between the source electrode and the gate electrode is small, and the capacitance between the gate and source electrodes is small.

Therefore, according to this liquid crystal display device,
Without increasing the capacitance between the gate and source electrodes of the TFT, the channel width of the
A large current can be supplied to T, and the driving duty can be increased to increase the pixel density.

Moreover, since the TFT has a small capacitance between the gate and drain electrodes, the waveform of the gate signal supplied from the gate wiring to the gate electrode is blunt due to the influence of the capacitance between the gate and source electrodes. Therefore, it is not necessary to widen the width of the gate wiring and lower its electrical resistance in order to compensate for the dulling of the waveform of the gate signal, so that the aperture ratio can be sufficiently increased.

Further, the liquid crystal display element is provided with the TFT
Since the gate-source electrode capacitance is small, the gate-source electrode capacitance hardly affects the writing charge charged to the pixel capacitance composed of the pixel electrode, the counter electrode, and the liquid crystal layer therebetween, Therefore, it is possible to reduce fluctuations in the writing state of the pixel region due to the influence of the capacitance between the gate and source electrodes, and to perform a favorable display.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, the liquid crystal display device of the present invention comprises a TFT in which at least the source electrode of the source electrode and the drain electrode is disposed at the channel region side edge of the TFT. By adopting a configuration in which a notch recessed from the edge to the inside of the electrode is provided, the channel width of the TFT can be substantially increased without increasing the gate-source electrode capacitance of the TFT. As a result, a large current can be supplied to this TFT, and the drive duty is increased to increase the pixel density.
The aperture ratio can be sufficiently increased by eliminating the necessity of increasing the wiring width of the gate wiring, and furthermore, the variation in the writing state of the pixel region due to the influence of the capacitance between the gate and source electrodes can be reduced, and a good display can be performed. It is like that.

In the liquid crystal display device according to the present invention, the T
Among the source electrode and the drain electrode of the FT, at least the source electrode has a shape in which a plurality of cutouts recessed in the electrode inward direction from the edge at the channel region side are provided at predetermined intervals. In this way, the capacitance between the gate and source electrodes of the TFT can be further reduced, and the substantial channel width can be further increased.

In the TFT, the drain electrode is also formed in such a shape that at least one notch recessed in the electrode inward from the edge is provided at the edge on the channel region side. It is more preferable that the cutout portion of the electrode is configured to face at least one cutout portion provided at the edge of the source electrode on the channel region side. Not only the capacitance between the drain electrodes but also the capacitance between the gate and drain electrodes can be reduced, and the dullness of the waveform of the gate signal due to the influence of the capacitance between the electrodes can be further reduced.

The present invention can be applied to various active matrix liquid crystal display devices such as TN (twisted nematic) type, STN type (super twisted nematic) type, scattering effect type, ferroelectric or antiferroelectric liquid crystal display device. .

In particular, a ferroelectric or antiferroelectric liquid crystal display device in which a ferroelectric liquid crystal or an antiferroelectric liquid crystal is sealed between a pair of substrates has a large pixel capacity, so that a large current can flow through the TFT. According to the present invention, the channel width of the TFT can be substantially increased without increasing the capacitance between the gate and source electrodes of the TFT, so that a large current can flow through the TFT. Therefore, it is possible to increase the pixel density by increasing the driving duty, eliminate the need to increase the wiring width of the gate wiring, sufficiently increase the aperture ratio, and furthermore, by the influence of the capacitance between the gate and source electrodes. Good display can be performed with less variation in the writing state of the pixel area.

[0030]

1 and 2 show a first embodiment of the present invention. FIG. 1 is a plan view of a part of a TFT substrate of an active matrix liquid crystal display element, and FIG. 2 is a TFT of FIG.
It is an enlarged view of a part.

The TFT substrate 11 is a transparent substrate made of glass or the like, and a plurality of transparent pixel electrodes 12 arranged in a matrix in the row direction and the column direction on its inner surface, that is, a surface facing a not-shown counter substrate. And a plurality of TFTs 13 arranged corresponding to these pixel electrodes 12 and having a source electrode 17 connected to the corresponding pixel electrode 12.
A plurality of gate wirings 19 for supplying gate signals to the gate electrodes 14 of the TFTs 13 in each row;
A plurality of data wirings 20 for supplying data signals to the drain electrode 18 of T13 are provided.

The TFT 13 is provided on a gate electrode 14 formed on the substrate 11, a gate insulating film 15 covering the gate electrode 14, and provided on the gate insulating film 15 so as to face the gate electrode 14. an i-type semiconductor film 16,
The source electrode 17 and the drain electrode 18 are provided on both sides of the i-type semiconductor film 16. The source electrode 17 and the drain electrode 18 are formed on the i-type semiconductor film 16, respectively. And a conductive metal film formed on the n-type semiconductor film for forming the source and drain regions.

The i-type semiconductor film 16 of the TFT 13
The n-type semiconductor film as the lower layer film of the source electrode 17 and the drain electrode 18 is made of amorphous silicon.

In this liquid crystal display device, the TF
Of the source electrode 17 and the drain electrode 18 of T13,
The source electrode 17 has at least one notch 17a which is recessed in the inward direction of the electrode 17 from the edge of the TFT 13 on the channel region (region between the source electrode 17 and the drain electrode 18) side of the TFT 13. It is formed in a given shape.

In this embodiment, the source electrode 1
Are formed in a comb-tooth shape having a plurality of (three in the figure) cutouts 17a provided at predetermined intervals at the channel region side edge.

Each of the plurality of cutouts 17a is formed in a rectangular shape whose both side edges are respectively substantially perpendicular to the channel region side edge and the inner back edge is substantially parallel to the channel region side edge. The length (the distance from the channel region side edge to the inner depth edge) is set to be slightly larger than the length of the source electrode 17 overlapping the i-type semiconductor film 16 and the width (the distance between both side edges) is set. Is about 2μ
m to 4 μm.

The gate wiring 19 is formed on the substrate 11 integrally with the gate electrode 14 of the TFT 13. Note that the gate insulating film 15 is
This is a single-layer transparent insulating film formed over the entire T array region, and the gate wiring 11 is covered with the gate insulating film 15 except for its terminal portions.

On the other hand, the data wiring 12 is formed on the gate insulating film 15 and is connected to the drain electrode 18 of the TFT 13. In this embodiment, the data wiring 12 is formed integrally with the drain electrode 18 of the TFT 13, but the TFT 13 is covered with an interlayer insulating film, and the data wiring 12 is formed thereon.
The data line 12 may be connected to the drain electrode 18 of the TFT 13 at a contact hole provided in the interlayer insulating film.

The pixel electrode 12 is formed on the gate insulating film 15. A source electrode 18 of a TFT 13 corresponding to the pixel electrode 12 is connected to a side edge of the pixel electrode 12. I have. Although not shown in the drawing, an alignment film is provided on the inner surface of the TFT substrate 11 so as to cover the plurality of pixel electrodes 12.

The liquid crystal display element is provided with the TFT substrate 11 and an inner surface (a single film-shaped transparent counter electrode facing the plurality of pixel electrodes 12 on a surface facing the TFT substrate 11). An unillustrated counter substrate (transparent substrate) having an alignment film formed thereon is joined via a not-shown frame-shaped sealing material, and a liquid crystal (not shown) is provided between the substrates in a region surrounded by the sealing material. Is enclosed.

In the liquid crystal display device of this embodiment, a ferroelectric liquid crystal or an antiferroelectric liquid crystal is placed between a pair of substrates (TFT substrate 11 and counter substrate) so that the direction of the normal line of the smectic layer structure is changed. It is a ferroelectric or antiferroelectric liquid crystal display element that is sealed by being regulated along a predetermined direction by the alignment film, and although not shown in the drawing, polarizing plates are respectively provided on the outer surfaces of the pair of substrates. , Each transmission axis is oriented in a predetermined direction.

In this liquid crystal display device, the TFT 13 is
Of the source electrode 17 and the drain electrode 18, the source electrode 17 is formed in a shape in which a notch 17 a that is recessed in the inward direction of the electrode 17 from the edge at the channel region side edge of the TFT 13 is provided. 2, the current path between the source electrode 17 and the drain electrode 18 when the TFT 13 is turned on, as shown by a broken line in FIG.
The drain electrode 18 is formed not only between the edge of the portion without the mark and the drain electrode 18, but also between the side edge of the cutout portion 17 a of the source electrode 17 and the drain electrode 18.

That is, the TFT 13 has a plurality of cutouts 17 a at the edge of the source electrode 17 on the channel region side.
Is formed in a shape provided with
Is turned on, the current flowing between the source electrode 17 and the drain electrode 18 via the i-type semiconductor film 16 is between the edge of the portion of the source electrode 17 where the notch 17 a is not formed and the drain electrode 18. In addition, the current flows between the side edge of the cutout portion 17 a of the source electrode 17 and the drain electrode 18.

The notch 17a of the source electrode 17
Of the current path formed between the side edge of the drain electrode 18 and the drain electrode 18, that is, the current path outside the region between the edge of the portion of the source electrode 17 where the notch 17 a is not formed and the drain electrode 18. The spread width of one side is about 1 μm to 2 μm, and in this embodiment, as described above, the notch 17
Since the width of “a” is about 2 μm to 4 μm, the region of the i-type semiconductor film 16 corresponding to the cutout portion 17a of the source electrode 17 can be effectively used as a current path when the TFT is turned on with almost no waste. it can.

Therefore, the TFT 13 substantially has
The edge of the portion of the source electrode 17 where the notch 17a is not provided has a larger channel width than the apparent channel width where the edge of the drain electrode 18 faces each other.

In the TFT 13, the source electrode 17 has the notch 17a at the edge on the channel region side.
Is formed in a shape provided with a notch, the substantial channel width is the channel width of a general TFT in which the edges of the source electrode 17 and the drain electrode 18 on the channel region side are straight edges without the notch, respectively. However, the facing area between the source electrode 17 and the gate electrode 18 is smaller than that of the general TFT, and the capacitance between the gate and the source electrode (floating capacitance between the gate electrode 14 and the source electrode 17).
Is small.

In this embodiment, the source electrode 17 is
An electrode 17 is connected to the edge on the channel region side from the edge.
Since the plurality of notches 17a recessed inward are formed in a shape provided at a predetermined interval, the capacitance between the gate and source electrodes of the TFT is further reduced, and the substantial channel width is further reduced. Can be bigger.

Therefore, according to this liquid crystal display device,
The gate / source of the TFT 13 having a semiconductor film made of amorphous silicon having lower electron mobility than single crystal silicon (i-type semiconductor film 6 and n-type semiconductor film which is a lower film of the source electrode 7 and the drain electrode 8). Without increasing the inter-electrode capacitance, the channel width can be substantially increased to allow a large current to flow through the TFT 13, and the driving duty can be increased to increase the pixel density.

Further, the TFT 13 has its gate
Since the capacitance between the drain electrodes is small, the waveform of the gate signal supplied from the gate wiring 19 to the gate electrode 14 is less likely to be blunt due to the influence of the capacitance between the gate and source electrodes. It is not necessary to widen the width of the gate wiring 19 and lower its electrical resistance in order to compensate for this, so that the aperture ratio can be made sufficiently high.

Further, this liquid crystal display element is provided with the above-mentioned TFT.
13 has a small capacitance between the gate and source electrodes, so that the capacitance between the gate and source electrodes is charged to the pixel capacitance composed of the pixel electrode 12 and a counter electrode provided on a counter substrate (not shown) and a liquid crystal layer therebetween. The change in the writing state in the pixel area due to the influence of the capacitance between the gate and the source electrode is less affected by the writing charge, and a favorable display can be performed.

The liquid crystal display device of the above embodiment is a ferroelectric or antiferroelectric liquid crystal display device in which a ferroelectric liquid crystal or an antiferroelectric liquid crystal is sealed between a pair of substrates. Therefore, it is necessary to allow a larger current to flow through the TFT 13. However, as described above, the channel width is substantially increased without increasing the capacitance between the gate and source electrodes of the TFT 13. Since a large current can be passed through the TFT 13, the drive duty is increased to increase the pixel density, and it is not necessary to increase the width of the gate wiring, so that the aperture ratio is sufficiently increased. Good display can be performed with less variation in the writing state of the pixel region due to the influence of the gate-source electrode capacitance.

FIG. 3 shows a TF according to a second embodiment of the present invention.
FIG. 3 is an enlarged view of a TFT portion of a T substrate, and this embodiment shows a TFT portion.
The source electrode 17 of the FT 13 is formed in a shape provided with a plurality of cutouts 17a which are recessed in the electrode 17 inward from the edge at the channel region side edge.
The drain electrode 18 of the FT 13 has a plurality of cutouts 18 (the same number as the cutouts 17a of the source electrode 17) recessed into the electrode 18 from the end on the channel region side.
a, and the plurality of cutouts 18 a of the drain electrode 18 are respectively formed in the source electrode 1.
7 are opposed to the plurality of notches 17a.

FIG. 4 is an enlarged view of a TFT portion of a TFT substrate according to a third embodiment of the present invention. In this embodiment, a source electrode 17 of a TFT 13 is provided at an edge on a channel region side. A plurality of cutouts 17a recessed inward from the edge in the direction of the electrode 17 are formed.
The drain electrode 18 of the TFT 13 is recessed in the inward direction from the edge on the channel region side edge.
The notch 18a of the drain electrode 18 is formed with a plurality of notches 17a provided at the edge of the source electrode 17 on the channel region side.
1a is opposed to one notch (the center in the figure) 17a.

It should be noted that the above-described second and third embodiments employ T
The drain electrode 18 of the FT 13 also has a notch 18a recessed in the inward direction from the edge on the channel region side edge.
Are formed in a shape provided with a symbol. However, since the other configuration is the same as that of the above-described first embodiment, the duplicate description is given the same reference numerals in the drawings and omitted.

According to the second and third embodiments, T
Since the notch 18a is also provided in the drain electrode 18 of the FT 13, not only the capacitance between the gate and the drain electrode of the TFT 13 but also the capacitance between the gate and the drain electrode is reduced, and the gate signal due to the influence of the capacitance between these electrodes is reduced. Of the waveform can be further reduced.

In the above embodiment, the semiconductor film of the TFT 13 (the i-type semiconductor film 16 and the n-type semiconductor film which is the lower layer film of the source electrode 17 and the drain electrode 18) is formed of amorphous silicon. The semiconductor film of the TFT 13 may be formed of polysilicon. Polysilicon has a lower electron mobility than single crystal silicon, but has a higher electron mobility than amorphous silicon. When formed of silicon, the source electrode 17 or the source electrode 17 may be used.
And the number of cutouts 17a and 18a provided in the drain electrode 18 may be smaller than in the above embodiment.

Although the liquid crystal display device of the above embodiment is a ferroelectric or antiferroelectric liquid crystal display device, the present invention is not limited to a ferroelectric or antiferroelectric liquid crystal display device.
The present invention can be applied to various active matrix liquid crystal display elements such as a TN (twisted nematic) type, an STN type (super twisted nematic) type, and a scattering effect type.

[0058]

According to the liquid crystal display device of the present invention, the TFT is
Of the source electrode and the drain electrode, at least the source electrode was formed in a shape in which a notch recessed in the electrode inward direction from the edge at the channel side edge of the TFT was provided. The TFT
Without increasing the gate-source electrode capacitance, the channel width can be substantially increased to allow a large current to flow through the TFT, and the drive duty can be increased to increase the pixel density and to increase the gate wiring. No need to widen the wiring width of the, to make the aperture ratio sufficiently high,
Good display can be performed by reducing the variation in the writing state of the pixel region due to the influence of the gate-source electrode capacitance.

In the liquid crystal display device of the present invention,
Among the source electrode and the drain electrode of the FT, at least the source electrode has a shape in which a plurality of cutouts recessed in the electrode inward direction from the edge at the channel region side are provided at predetermined intervals. In this manner, the capacitance between the gate and source electrodes of the TFT can be reduced, and the substantial channel width can be further increased.

In the TFT, the drain electrode is also formed in such a shape that at least one notch recessed in the electrode inward from the edge is provided at the edge on the channel region side. It is more preferable that the cutout portion of the electrode is configured to face at least one cutout portion provided at the edge of the source electrode on the channel region side. Not only the capacitance between the drain electrodes but also the capacitance between the gate and drain electrodes can be reduced, and the dullness of the waveform of the gate signal due to the influence of the capacitance between the electrodes can be further reduced.

The present invention is particularly effective for a ferroelectric or antiferroelectric liquid crystal display. A ferroelectric or antiferroelectric liquid crystal in which a ferroelectric liquid crystal or an antiferroelectric liquid crystal is sealed between a pair of substrates. Since the liquid crystal display element has a large pixel capacity, it is necessary to allow a large current to flow through the TFT. However, according to the present invention, the channel between the gate and the source electrode of the TFT can be increased without increasing the capacity. Since the width can be substantially increased to allow a large current to flow through the TFT, the drive duty is increased to increase the pixel density, and it is not necessary to increase the width of the gate wiring. The aperture ratio can be made sufficiently high, and the variation in the writing state of the pixel region due to the effect of the capacitance between the gate and source electrodes can be reduced, and good display can be performed.

[Brief description of the drawings]

FIG. 1 is a plan view of a part of a TFT substrate of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is an enlarged view of a TFT portion of FIG.

FIG. 3 shows a TFT substrate according to a second embodiment of the present invention;
The enlarged view of the FT part.

FIG. 4 shows a TFT substrate according to a third embodiment of the present invention;
The enlarged view of the FT part.

FIG. 5 is a plan view of a part of a TFT substrate of a conventional liquid crystal display element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... TFT substrate 12 ... Pixel electrode 13 ... TFT 14 ... Gate electrode 15 ... Gate insulating film 16 ... i-type semiconductor film 17 ... Source electrode 17a ... Notch 18 ... Drain electrode 18a ... Notch 19 ... Gate wiring 20 ... Data wiring

Continuation of the front page F term (reference) 2H092 GA14 GA26 JA24 JA29 JA38 JA42 JB13 JB23 JB32 JB33 JB38 KA04 KA05 KA07 NA07 NA22 NA27 PA06 QA07 QA10 QA13 QA14 5C094 AA21 AA31 BA03 BA43 EA04 5F110 AA02 GG01 BB02 HK16 HK21 HM04 NN02 NN72

Claims (4)

[Claims] A plurality of pixel electrodes arranged in a matrix in a row direction and a column direction on an inner surface of one of a pair of substrates arranged opposite to each other, and are arranged corresponding to these pixel electrodes, respectively. A plurality of thin film transistors each having a source electrode connected to the corresponding pixel electrode, a plurality of gate wirings each supplying a gate signal to a gate electrode of each row of thin film transistors, and a data signal supplied to a drain electrode of each column of thin film transistors. A plurality of data wirings are provided, and on the inner surface of the other substrate, a counter electrode facing the plurality of pixel electrodes is provided, and an active matrix liquid crystal display element in which liquid crystal is sealed between the pair of substrates is provided. Wherein at least the source electrode of the source electrode and the drain electrode of the thin film transistor is the thin film A liquid crystal display element, wherein at least one notch is formed in an edge of a transistor on a channel region side inwardly from the edge in an electrode direction. 2. A semiconductor device comprising: a plurality of notches formed in a source region and a drain electrode of a thin film transistor, wherein at least the source electrode has a plurality of cutouts recessed inward from the edge on the channel region side of the thin film transistor; 2. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is formed in a shape provided at intervals of. 3. A drain electrode of the thin film transistor is formed in a shape in which at least one notch recessed inward from the edge on the channel region side is provided at an edge on the channel region side of the thin film transistor. 2. The liquid crystal display device according to claim 1, wherein the notch of the drain electrode faces at least one notch provided at an edge of the source electrode on the channel region side. 4. A ferroelectric liquid crystal or an antiferroelectric liquid crystal is sealed between a pair of substrates.
4. The liquid crystal display device according to any one of items 1 to 3.