JPH0272329A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To reduce the size of a thin film transistor(TFT) and to improve the opening rate by projecting the drain electrode of the TFT from a video signal line in the extending direction of a scanning signal line, and projecting the gate electrode of the TFT from the scanning signal line in the extending direction of the video signal line. CONSTITUTION:The drain electrode SD2 of the TFT is projected form the video signal line DL in the extending direction of the scanning signal line GL and the gate electrode GT of the TFT is projected from the scanning signal line GL in the extending direction of the video signal line DL. The video signal line DL where the gate electrode GT is projected and the drain electrode SD2 projected along the scanning signal line GL constitute the substantial drain area of the TFT in an L shape. Therefore, the channel width size of the TFT can be increased. Consequently, the size of the TFT is reduced and the opening rate of picture elements is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique that is effective when applied to a liquid crystal display device, particularly a liquid crystal display device configured using an active matrix method.

[Conventional technology]

A plurality of pixels are arranged in a matrix in a liquid crystal display section of an active matrix type liquid crystal display device.

Each pixel is arranged within a region surrounded by a scanning signal line (gate signal i) and a video signal line (drain signal line). A plurality of scanning signal lines are arranged and extend in the horizontal direction. A plurality of video signal lines are arranged and extend in the vertical direction intersecting the scanning signal lines.

Each pixel is composed of a series circuit of a thin film transistor (TPT) and a transparent pixel electrode. A thin film transistor is constructed by sequentially stacking a gate insulating film, a semiconductor layer (channel forming region), a source electrode, and a drain electrode on a gate electrode. The source electrode is electrically connected to the transparent pixel electrode. The drain electrode is integrally constructed and electrically connected to the video signal line. The electrode to the gate 1 is integrally constructed and electrically connected to the scanning signal line.

Regarding this type of liquid crystal display device, for example, Japan Display '86 (1986), No. 208
Pages 211 to 211 (rAcLive Matrix C
o1orLCD Fabricated by Usi
ng Redundancy and RepairSy
stemJ pp, 208-211. Japan Di
spray'86).

[Problem to be solved by the invention]

As the screen size (area) of liquid crystal display devices becomes larger, the size of thin film transistors in pixels tends to decrease. Since the driving ability of this thin film transistor decreases, it becomes necessary to increase the size to ensure the driving ability. For this reason, the amount corresponding to the increase in the size of the thin film transistor is
There is a problem in that the size of the transparent pixel electrode is reduced and the aperture ratio is reduced.

In addition, the transparent pixel electrode of the pixel is patterned using etching, and a jagged surface is formed on the etched end surface due to crystallinity. When this transparent pixel electrode is subjected to an etching mask peeling treatment or a cleaning treatment after etching, the etched peripheral portion, that is, the jagged surface portion, is peeled off from the underlying insulating film. In particular, at the connection between the source electrode of the thin film transistor and the transparent pixel electrode, the connection between the two is disconnected.

Therefore, there is a problem in that the manufacturing yield of the liquid crystal display device is reduced.

An object of the present invention is to provide a technique that can reduce the size of a thin film transistor and improve the aperture ratio in a liquid crystal display device.

Another object of the present invention is to provide a technique that can improve manufacturing yield in a liquid crystal display device.

The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

(1) In a liquid crystal display device, the drain electrode of the thin film transistor protrudes from the video signal line along the direction in which the scanning signal line extends, and the gate electrode of the thin film transistor projects from the scanning signal line in the direction in which the video signal line extends. make it stand out.

(2) In a liquid crystal display device, an adhesive layer is provided between a peripheral region of a transparent pixel electrode of a pixel and an underlying layer thereof.

[For production]

According to the above-mentioned means (1), the substantial drain region of the thin film transistor is formed in an L-shape by the video signal line in the portion where the gate electrode projects and the drain electrode projecting along the scanning signal line; The channel width dimension of the thin film transistor can be increased, thus reducing the size of the thin film transistor.

The aperture ratio of pixels can be improved.

According to the above-mentioned means (2), it is possible to improve the adhesive strength between the peripheral area of the transparent pixel 71 and the base layer.
Peeling of the transparent pixel electrode from the underlying layer can be reduced, and the manufacturing yield of the liquid crystal display device can be improved.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below along with an embodiment in which the present invention is applied to a liquid crystal display device employing an active matrix method.

In addition, in an attempt to explain the embodiments, parts having the same functions are given the same reference numerals, and repeated explanation thereof will be omitted.

〔Example〕

A liquid crystal display section of a liquid crystal display device according to an embodiment of the present invention is shown in FIG. 1 (a plan view of main parts), and FIG. 2 shows a cross section taken along the line n--■ in FIG. 1.

As shown in FIGS. 1 and 2, the liquid crystal display device includes 1.
Lower transparent glass substrate SU having a thickness of about 1 mm1
A thin film transistor T is placed on the inner surface (liquid crystal side) of B1.
Has PT. This thin film transistor TPT is arranged within the liquid crystal display section. Thin film transistor T
PT mainly consists of a gate pole GT, an insulating film G1. It is composed of an i-type single conductor layer AS, a source electrode (or drain electrode) SDI, and a drain electrode (or source electrode) SD2.

The gate ff1tiGT is formed of, for example, a Cr film g1 deposited by sputtering and having a thickness of about 1100 [layers]. This gate electrode GT is formed in the same manufacturing process (same conductive layer) as the scanning signal line (gate signal line or horizontal signal line) OL, and is integrated with the scanning signal line GL.

For example, the scanning signal line GL is formed by forming AQ-5i on the Cr film g1.
It is formed of a composite film in which films g2 are laminated. AQ-5i
l1g2 is deposited by sputtering, for example, and has a thickness of about 1000 [
Formed with a film thickness comparable to that of a human body. This AQ-S i p
li g 2 is configured to mainly reduce the resistance value of the scanning signal line GL and increase the transmission speed of the scanning signal. The gate electrode GT is formed integrally with the lower layer Cr film g1 of the scanning signal SQL. The scanning signal lines GL extend horizontally as shown in FIG. 1, and a plurality of scanning signal lines GL are arranged vertically (not shown).

As shown in FIG. 1, the gate electrode GT is connected to the scanning signal line G.
At the intersection between L and the video signal line DL, the scanning signal line G is inserted along the direction in which the video signal line DL extends (downward)
It is configured to protrude from L. In other words, the gate electrode GT has a convex planar shape protruding from the scanning signal line GL.

The insulating film GI is formed on the gate electrode GT and the scanning signal line GL. Insulating film GT.

For example, a silicon nitride film deposited by a plasma CVD method is used to have a thickness of about 3,500 [layers]. The insulating film GI is mainly used as a gate insulating film of the thin film transistor TPT.

The i-type semiconductor layer AS is formed in an island shape above the gate insulating film GI. The i-type semiconductor layer AS is formed of an amorphous silicon film or a polycrystalline silicon film deposited by the CVD method, and has a thickness of about 25
It is formed with a film thickness of about 0.00 [persons]. i-type semiconductor J
'1FAS is mainly used as a channel forming region of the thin film transistor TPT.

The source electrode SDI and the drain electrode SD2 are each provided on the i-type medium conductor layer AS to be spaced apart from each other. The source electrode SDI and the drain electrode SD2 are operationally switched between source and drain when the bias polarity of the circuit changes. In other words, the thin film transistor TPT has a bidirectional structure similar to the insulated gate field effect transistor FET.The six source electrodes SDI and drain electrodes SD2 are formed in the same manufacturing process and clearly show a cross-sectional structure. However, for example, it is composed of a composite film in which a Go-type semiconductor layer and a Cr film are sequentially laminated from the lower layer side in contact with the i-type semiconductor layer As. It is formed of an n-type half body layer, an amorphous silicon film or a polycrystalline silicon film, and has a thickness of about 500 [layers].

The i-type semiconductor layer is configured to reduce the contact resistance value between the i-type semiconductor layer AS and the Cr film. The Cr film is deposited by, for example, a sputtering method, and is formed to have a thickness of about 600 [layers]. This Cr film is connected to the source electrode SD as described above.
In addition to forming the drain electrode SD2 and the source electrode SDI, it is also used as an adhesive layer between the source electrode SDI and the transparent electrode IT○1, and an adhesive layer between the transparent electrode ITOI and the insulating film GI.

The video signal line DL is mainly composed of a Cr film like the source electrode SDI and drain electrode SD2. Further, the video signal line DL may be formed of a composite film in which an AQ film, an ITO film, etc. are laminated on a Cr film in order to increase the transmission speed of the video signal.

The video signal line DL is connected to the scanning signal line GL as shown in FIG.
Although not shown, a plurality of them are arranged in the horizontal direction.

The drain electrode SD2 is integrally constructed and electrically connected to the video signal line DL. The drain electrode SD2 is
As shown in FIG. 1, the scanning signal line GL and the video signal line DL
At the intersection of

It is configured to protrude from the video signal line DL along the direction in which the scanning signal line GL extends (to the right).

In other words, the drain electrode SD2 has a convex planar shape protruding from the video signal line DL.

The source 5tasDi is spaced apart by a predetermined interval from at least five protruding train electrodes SD2 and a protruding gate electrode GT portion along the video signal line DL (this portion is used as the video signal line DL and the drain electrode SD2). It is placed in the same position. This source electrode SD
I has a transparent electrode (transparent pixel electrode) provided for every 5 pixels.
IrO2 is connected. The transparent electrode I'r01 is formed on the upper layer of the source electrode SDI, and the transparent electrode I'r01 is formed on the source electrode SDI.
It goes over the stepped shape of I and is directly bonded to the surface. The transparent electrode ITOI constitutes one of the pixel electrodes of the liquid crystal display section. The transparent electrode ITOI is provided on the insulating film GI, and has a rectangular planar shape, although it is not limited thereto. Transparent 1. BIT○1 is formed of an ITO film (or NESA film), and is deposited by, for example, a sputtering method, and has a thickness of about 1200
Form with a film thickness of about [ON].

The peripheral part of the transparent electrode ITOI and this transparent electrode IT
An adhesive layer S is provided between the base layer of ○1. The adhesive layer S is configured in a frame shape along the periphery of the transparent electrode ITOI, and a part of the adhesive layer S is configured integrally with the source electrode SDI. In other words, the adhesive layer S is a transparent electrode ITOI
It is made of an ITO film and a Cr film with high adhesiveness.

In this manner, in the liquid crystal display device, the train electrode SD2 of the aPIA transistor TPT is made to protrude from the video signal line DL along the direction in which the scanning signal line GL extends, and scanning is performed along the direction in which the video signal line DL extends. Due to the structure in which the gate electrode GT of the thin film transistor TFT protrudes from the signal line GL, the portion of the video signal line DL where the gate electrode GT protrudes and the drain electrode SD2 protruding along the scanning signal line GL form the substantial part of the thin film transistor TPT. By configuring the drain region SD2 in an L-shape, it is possible to increase the channel width dimension of the thin film transistor TPT (improve the driving ability), thereby reducing the size of the thin film transistor TPT and improving the aperture ratio of the pixel. Can be done.

In addition, in a liquid crystal display device, a transparent electrode ITOI of one pixel is used.
An adhesive layer S is formed between the peripheral region of
will be established. With this configuration, it is possible to improve the adhesive strength between the peripheral region of the transparent electrode ITOI and the underlying insulating film G2, so that in the patterning process, etching mask peeling process, cleaning process, etc. of the transparent IFi2Tot, It is possible to reduce peeling of the transparent type tl I T O1 from the underlying insulating film GI, and improve the manufacturing yield of the liquid crystal display device.

Similarly, the source electrode SDI to which the transparent electrode ITOI is connected is made of a highly adhesive material such as a Cr film. With this configuration, the source electrode SDI and the transparent electrode ITO
Since it is possible to improve the adhesion with I and reduce the peeling of both, it is possible to improve the manufacturing yield of liquid crystal display devices.

A protective film PSVI is provided on the thin film transistor TPT and the transparent electrode IrO1. The protective film PSVI is formed mainly to protect the thin film transistor TPT from moisture, etc., and a film having high transparency and good moisture resistance is used. The protective film PSVI is 5, for example plasma C
It is formed from a silicon oxide film or silicon nitride film deposited by the VD method,
It is formed with a film thickness of approximately 10 oooc.

A light shielding film LS is provided above the protective film PSVI on the thin film transistor TFT to prevent external light from entering the i-type semiconductor layer AS used as a channel formation region. The light-shielding film LS is formed of, for example, an AQ film, a Cr film, etc., so as to have high light-shielding properties and conductivity. There is.

The liquid crystal LC is defined and enclosed by a lower alignment film 0RII and an upper alignment film ○RI2 that set the orientation of liquid crystal molecules in a space formed between a lower transparent glass substrate SUB1 and an upper transparent glass substrate 5UB2. ing.

The lower alignment film 0R41 is formed on the protective film PSVI on the lower transparent glass substrate 5UBl side.

On the inner surface (liquid crystal side) of the upper transparent glass substrate 5UB2, a color filter FIL, a protective film PSv2, a common transparent electrode (common transparent pixel electrode) ITO2, and the upper alignment film 0RI2 are sequentially laminated.

The common transparent electrode ITO2 is connected to the lower transparent glass substrate 5U.
It faces the transparent electrode ITOI provided for each pixel on the BI side and is configured integrally with another adjacent common transparent electrode ITO2.

The color filter FIL is formed by dyeing a dyed base material made of a resin material such as acrylic resin with a dye for each pixel. Dyeing is done using photolithography technology.

The protective film PSV2 is provided to prevent the dyes used to dye the color filter FIL into different colors from leaking into the liquid crystal LC. The protective film PSV2 is made of, for example, a transparent resin material such as acrylic resin or epoxy resin.

This liquid crystal display device has a lower transparent glass substrate 5UBl side,
Each layer on the upper transparent glass substrate 5UB2 side is formed separately, and then the upper and lower transparent glass substrates 5UBI and 5UB2 are formed separately.
It is assembled by overlapping the two and sealing the liquid crystal LC between them.

Lower transparent glass substrate SUB 1, upper transparent glass substrate 5
A polarizing plate P○L is formed on the outer surface of each UB2.

As above, the invention made by the present inventor has been specifically explained based on the above embodiments, but the present invention is not limited to the above embodiments, and can be modified in various ways without departing from the gist thereof. Of course.

For example, in the present invention, an adhesive layer S that improves the adhesion between the transparent electrode ITO1 of the pixel and its base layer is attached to the source electrode SD.
It may be formed only in the I portion.

〔Effect of the invention〕

A brief explanation of the effects obtained by typical inventions disclosed in this application is as follows.

In a liquid crystal display device, the aperture ratio of pixels can be improved.

Further, in the liquid crystal display device, manufacturing yield can be improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of a main part showing a liquid crystal display section of a liquid crystal display device according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the line nn in FIG. 1. In the figure, SUB...transparent glass substrate, OL...scanning signal line, DL...video signal line, GI...insulating film, GT
...gate electrode, AS...i-type semiconductor layer, SDI
...Source electrode, SD2...Drain electrode, S...
Adhesive layer, PSV...protective film, LS...light shielding film, LC
...Liquid crystal, TPT...Thin film transistor. Figure 1

Claims (1)

[Claims] 1. A pixel formed by a series circuit of a thin film transistor and a transparent pixel electrode is arranged at the intersection of a scanning signal line extending in the horizontal direction and a video signal line extending in the vertical direction. In the liquid crystal display device, the drain electrode of the thin film transistor protrudes from the video signal line along the extending direction of the scanning signal line, and the drain electrode of the thin film transistor protrudes from the scanning signal line along the extending direction of the video signal line. A liquid crystal display device characterized by having a protruding gate electrode. 2. In a liquid crystal display device in which a pixel formed by a series circuit of a thin film transistor and a transparent pixel electrode is arranged at the intersection of a scanning signal line and a video signal line, the peripheral area of the transparent pixel electrode and the transparent pixel electrode are A liquid crystal display device characterized in that an adhesive layer is provided between the base layer and the base layer. 3. The liquid crystal display device according to claim 2, wherein the adhesive layer is provided at least in a portion where the source electrode of the thin film transistor and the transparent pixel electrode are connected.