JPH08234236A - Production of liquid crystal display substrate - Google Patents

Abstract

PURPOSE: To prevent the occurrence of dot defects by forming by a protective film to cover semiconductor switching elements and pixel electrodes formed on a transparent substrate, then forming apertures for exposing a part of the contours of the pixel electrodes in this protective film. CONSTITUTION: The semiconductor switching elements and the pixel electrodes ITO 1 are formed on the liquid crystal side surface of the one transparent substrate SUB 1 of the transparent substrates arranged to face each other via liquid crystal. The protective film PSV 1 to cover these semiconductor switching elements and the pixel electrodes ITO 1 is formed. In the protective film PSV 1, after its formation, the slit openings SH to expose a part of the contours of the pixel electrodes ITO are formed. Conductive foreign matters adhered between the pixel electrodes ITO 1 and wiring layers (scanning signal lines or video signal lines DL) adjacent thereto are removed. As the result, even if the foreign matters consisting of the semiconductors made to remain at the time of forming the semiconductor switching elements are deposited, the removal of such foreign matters is made possible and the normal driving of the pixel electrodes is assured. The occurrence of the dot defects is thus prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a liquid crystal display substrate, and more particularly to a method of manufacturing a so-called active matrix type liquid crystal display substrate.

[0002]

2. Description of the Related Art For example, an active matrix type liquid crystal display substrate is arranged in a matrix by laminating various materials on respective liquid crystal side surfaces of transparent glass substrates which are arranged to face each other with a liquid crystal interposed therebetween. Each pixel and an electronic circuit for operating each pixel are incorporated.

In the case of manufacturing such a liquid crystal display substrate, the transparent glass substrates are sequentially laminated with different material layers each having a predetermined pattern on their surfaces, and then they are arranged to face each other. The liquid crystal is sealed in.

Further, in this case, each material layer consisting of each pattern is formed by using a so-called photolithography technique, whereby finely processed pixels and electronic circuits are formed.

[0005]

However, in the liquid crystal display substrate manufactured in this way, in the process of sequentially laminating various material layers having a predetermined pattern as described above, the material which is not removed in accordance with the pattern ( It is unavoidable that the foreign matter (usually called foreign matter) often remains.

If such a foreign substance is electrically conductive, it has a harmful effect of short-circuiting the finally formed electronic circuit.

In this case, there are relatively many short circuits between the pixel electrode and the wiring layer arranged adjacent to this pixel electrode, which causes a so-called point defect that the pixel electrode does not operate normally. Was there.

The present invention has been made under these circumstances, and an object thereof is to provide a method of manufacturing a liquid crystal display substrate capable of preventing the occurrence of so-called point defects.

[0009]

Of the inventions disclosed in the present application, a representative one will be briefly described below.
It is as follows.

Means 1. At least a semiconductor switching element and a pixel electrode are formed on a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and a protective film is formed to cover the semiconductor switching element and the pixel electrode. In the method for manufacturing a liquid crystal display substrate as described above, after forming the protective film, a step of forming an opening for exposing at least a part of the contour of the pixel electrode in the protective film is included. is there.

Means 2. At least a semiconductor switching element and a pixel electrode are formed on a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and a protective film is formed to cover the semiconductor switching element and the pixel electrode. In the method for manufacturing a liquid crystal display substrate, wherein the pixel electrode is formed on an insulating film, the pixel electrode is formed on the protective film outside the contour after the protective film is formed. The method is characterized by including a step of forming a slit-shaped opening reaching at least the insulating film in at least a part of a line surrounded by.

Means 3. At least a semiconductor switching element and a pixel electrode are formed on a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and a protective film is formed to cover the semiconductor switching element and the pixel electrode. In the method for manufacturing a liquid crystal display substrate described above, after forming the protective film, a step of forming an opening for exposing the pixel electrode including the contour thereof in the protective film is included. is there.

Means 4. In any one of means 1 to 3, the signal line is formed adjacent to the pixel electrode, and the signal line is electrically connected between the pixel electrode and the signal line in the opening formed in the protective film. When a foreign substance having a sexuality is present, a step of incinerating the foreign substance with a laser beam applied through the opening is included.

[0014]

According to the structure described in the means 1, the semiconductor remaining at the time of forming the semiconductor switching element is connected so as to connect the pixel electrode and the wiring layer arranged adjacent to the pixel electrode. Even if the foreign matter is adhered, the foreign matter is removed by forming the opening in the protective film.

This is because the foreign matter is also removed at the same time by the opening forming means (for example, etching) of the protective film.

In this case, the opening formed in the protective film is preferably formed so as to expose the entire contour of the pixel electrode, but it is not always necessary to do so. This is because, as a rule of thumb, it may be limited to the portion where the short circuit is most likely to occur, and there is also a portion where the pixel electrode itself is connected to another wiring layer.

Since the foreign matter can be removed in this manner, the pixel electrode can be normally driven, and so-called point defects can be prevented from occurring.

According to the structure of the means 2, the means 1 is particularly preferable when the pixel electrode is formed on the insulating film.
The same effect as that shown in can be obtained.

When the pixel electrode is formed on the insulating film, if the structure shown in the means 1 is carried out as it is, the insulating film is also removed and the peripheral portion of the pixel electrode is overhung.

Therefore, the slit-like opening formed in the protective film is formed at least on a part of the line surrounding the pixel electrode outside the contour so as to avoid the above-mentioned adverse effect.

According to the structure shown in the means 3, the same effect as the structure shown in the means 1 can be obtained, and at the same time, the effect that the transmittance in the pixel electrode forming region can be improved can be obtained. Become.

According to the structure described in the means 4, when the conductor made of a foreign substance other than the semiconductor is attached so as to connect between the pixel electrode and the wiring layer arranged adjacent to the pixel electrode. In addition, it is possible to incinerate and remove the laser beam as it is without performing the step of removing the protective film.

[0023]

The objects and features of the present invention will become apparent from the following description with reference to the drawings.

Example 1. << Active Matrix Liquid Crystal Display Device >> An embodiment in which the present invention is applied to an active matrix type color liquid crystal display device will be described below. In the drawings described below, components having the same function are designated by the same reference numeral, and repeated description thereof will be omitted.

<< Overall Structure of Liquid Crystal Display Module >> FIG.
FIG. 4 is an exploded perspective view showing each component of the liquid crystal display module MDL.

SHD is a frame-shaped shield case (metal frame) made of a metal plate, LCW is its display window, PNL.
Is a liquid crystal display panel, SPB is a light diffusing plate, MFR is an intermediate frame, BL is a backlight, BLS is a backlight support, and LCA is a lower case. Each member is stacked in a vertical arrangement as shown in the figure. Is a module MDL
Is assembled.

The module MDL is a shield case SH.
The whole is fixed by the claw CL and the hook FK provided on D.

The intermediate frame MFR is formed in a frame shape so that an opening corresponding to the display window LCW is provided, and the frame portion has a diffusion plate SPB, a backlight support BLS, and various circuit components in accordance with the shapes and thicknesses thereof. There are irregularities and openings for heat dissipation.

The lower case LCA also serves as a reflector for backlight light, and a reflection mountain RM is formed corresponding to the fluorescent tube BL so as to efficiently reflect light.

SUB1 and SUB2 are first and second transparent glass substrates which respectively constitute the liquid crystal display panel PNL. As will be described in detail later, a thin film transistor, a scanning signal line, and a scanning signal line are formed on the surface of the first transparent glass substrate SUB1.
Video signal lines, transparent pixel electrodes, etc. are formed, and a black matrix, color filters, common transparent pixel electrodes, etc. are formed on the surface of the second transparent glass substrate SUB2.
In this embodiment, as shown in this figure, the backlight BL
Are arranged on the second transparent glass substrate SUB2 side.

<< Outline of Matrix Section >> FIG. 1 is a plan view showing one pixel and its periphery of an active matrix type color liquid crystal display device to which the present invention is applied. FIG. 1 shows adjacent video signal lines and transparent pixel electrodes. 2 is a cross-sectional view showing a cross section taken along the line 1-1 of FIG. 2, and FIG.
FIG. 4 is a view showing a cross section taken along line 3-4, and FIG. 4 is a view showing a cross section taken along line 4-4 in FIG.

As shown in FIG. 2, each pixel has two adjacent scanning signal lines (gate lines or horizontal signal lines) GL.
And an adjacent two video signal lines (data line, drain line or vertical signal line) DL in an intersecting region (region surrounded by four signal lines). Each pixel includes a thin film transistor TFT, a transparent pixel electrode ITO1 and an additional capacitance element Cadd. The scanning signal line GL is bifurcated near the intersection with the video signal line DL. this is,
When one of the two lines of this portion is short-circuited with the video signal line DL, this is cut using a laser, and the other one (not cut) line does not become a line defect and operates normally. This is because.

Here, in this embodiment, in particular, the protective film PSV1 is formed so as to cover the pixel electrode ITO1,
A trace of the slit-shaped opening SH exposing the contour of the pixel electrode ITO1 remains on the protective film PSV1.

The slit-shaped opening SH is formed in the pixel electrode IT.
This is an opening for removing the conductive foreign matter attached between O1 and the wiring layer (scanning signal line GL or video signal line DL) adjacent to this pixel electrode ITO1. >> will be described later.

The slit-shaped openings SH are not formed at the four corners of the pixel electrode ITO in the figure, but the reason is that the pixel electrode ITO has a notched shape at the portions. Since the distance from the wiring layer is relatively large, the probability that the foreign matter will adhere and cause an electrical short circuit with the wiring layer will be small. Further, the slit-shaped opening SH is provided with the additional capacitance Cadd and the thin film transistor T.
It is not formed in the portion where the FT is formed. This is because it is a region connected to the pixel electrode ITO, so that it is a region in which electrical short circuit need not be particularly considered. However, the pixel electrode IT
It goes without saying that the slit-shaped opening SH may be formed in such a shape that the entire outline of O is exposed.

As shown in FIG. 3, a thin film transistor TFT and a transparent pixel electrode ITO1 are formed on the side of the first transparent glass substrate SUB1 based on the liquid crystal layer LC, and the second
On the transparent glass substrate SUB2 side of the color filter FI
L, a black matrix pattern BM for shading is formed. Silicon oxide film SI formed by dipping or the like on both surfaces of the transparent glass substrates SUB1 and SUB2
O is provided.

On the inner (liquid crystal LC side) surface of the second transparent glass substrate SUB2, a light shielding film BM and a color filter F are provided.
IL, protective film PSV2, common transparent pixel electrode ITO2 (C
OM) and the upper alignment film ORI2 are sequentially stacked. POL1 and POL2 are light shielding plates formed on the outer surfaces of the transparent glass substrates SUB1 and SUB2, respectively.

<< Thin Film Transistor TFT >> Next, referring to FIG.
3, the configuration on the first transparent glass substrate SUB1 side will be described in detail. When a positive bias is applied to the scanning signal line GL, the channel resistance between the source and the drain decreases, and when the bias is zero, the channel resistance increases.

One thin film transistor TFT is provided for each pixel.
Is provided. The thin film transistor TFT is formed on the scanning signal line GL, as shown in FIG. The surfaces of the gate electrodes (scanning signal lines GL) and scanning signal lines GL are covered with an anodized film AOF and an insulating film GI of silicon nitride, and these AOF and GI form a gate insulating film. An i film (intrinsic, intrinsic, unconducted with conductivity type determining impurity) amorphous silicon (S
i-type semiconductor layer As composed of i), a pair of source electrodes SD
1, having a drain electrode SD2. It should be understood that the source and drain are originally determined by the bias polarity between them, and the polarity is inverted during operation in the circuit of this liquid crystal display device, so it should be understood that the source and drain are switched during operation. However, in the following description, for convenience, one is fixed as the source and the other is fixed as the drain.

<< Gate Electrode [Scanning Signal Line GL] >> In this example, the scanning signal line GL is formed of a single-layer first conductive film g1. As the first conductive film g1, for example, an aluminum (Al) film formed by sputtering is used, and an anodic oxide film AOF of Al is provided thereon in a self-aligned manner.

<< Insulating Film GI >> In the thin film transistor TFT, the insulating film GI is used as a gate insulating film for giving an electric field from the scanning signal line GL to the semiconductor layer AS together with the anodized film AOF. As the insulating film GI, for example, a silicon nitride film formed by plasma CVD is selected,
With a thickness of 1200 to 2700Å (200 in this embodiment)
0 Å) formed. In this example, the insulating film GI is formed on the thin film transistor TFT portion, the additional capacitance Cadd, the source electrode SD1, the drain electrode SD2 portion, and the video signal line DL portion, and only the additional capacitance Cadd portion has an independent island shape. It is patterned into a shape along the drain electrode SD2 and the video signal line DL.

On the other hand, the insulating film G is formed on the entire scanning signal line GL.
The video signal line DL and the source electrode SD1 which are not covered with I and are adjacent to the additional capacitance Cadd are patterned and removed similarly to the semiconductor layer AS shown below. Insulation film G
The scanning signal line GL not covered with I is the anodic oxide film AO.
F is coated.

<< i-type semiconductor layer AS >> i-type semiconductor layer AS
In this example, the thin film transistor TFT portion and the additional capacitance C
Add, and the source electrode SD1 and the drain electrode SD2 are formed, and only the additional capacitance Cadd is formed into an independent island shape. Particularly, the drain electrode SD2 and the video signal line DL are formed.
It is patterned into a shape that follows. On the other hand, the scanning signal line GL is not entirely covered with the semiconductor layer AS,
The video signal line DL and the source electrode SD1 adjacent to the additional capacitance Cadd are patterned and removed similarly to the insulating film GI described above. The semiconductor layer AS is made of amorphous silicon and has a thickness of 200 to 2200Å (200 in this embodiment).
0 Å). The layer d0 is an N (+) type amorphous silicon semiconductor layer doped with phosphorus (P) for ohmic contact, and the i type semiconductor layer AS is present on the lower side,
It is left only where the conductive layer d2 (d3) exists on the upper side.

The i-type semiconductor layer AS is an anodic oxide film AOF for insulation separation at the intersection of the scanning signal line GL and the video signal line DL, and the intersection of GL and the source electrode SD1, the drain electrode SD2 and the additional capacitance Cadd. , Along with the insulating film GI, reduce line defects due to short circuit. In addition, the source electrode S
The N (+) type amorphous silicon d0, the i type semiconductor layer AS, and the insulating film GI are formed to extend from the lower part of D1 onto the transparent conductive film ITO1 (d1). As a result, the source electrode SD1 is connected to the transparent conductive film ITO1 (d1) without disconnection as will be described later. Further, even when the source electrode SD1 and the drain electrode SD2 are not properly patterned and these electrodes are left on the scanning signal line GL only in the portion of the anodic oxide film AOF, the anodic oxide film AOF is not formed.
Even a single film has a predetermined withstand voltage and can prevent a short circuit.

On the other hand, in this embodiment, the semiconductor layer AS and the insulating film GI below the video signal line DL extend over the transparent pixel electrode ITO, and serve to insulate the video signal line DL and the transparent pixel electrode ITO1. . Therefore, even if the distance between the video signal line DL and the transparent pixel electrode ITO1 is narrowed to form a bright liquid crystal display device with a high aperture ratio, a point defect due to a short circuit between the video signal line DL and the transparent pixel electrode ITO1 (d1). Can be prevented.

Since the semiconductor layer AS and the insulating film GI are processed using the same photoresist pattern, the number of photo processes can be reduced as compared with the method of processing the semiconductor layer AS and the insulating film GI with different photoresist patterns. Further, the short circuit probability is smaller than that in the case where the short circuit is prevented between the video signal line DL and the transparent pixel electrode ITO1 (d1) only by the insulating film GI. This is because the transparent conductive film ITO1 (d) is separated by dividing the photo-etching process of the semiconductor layer AS and the insulating film GI.
1) When the i-type semiconductor layer AS extending from the lower part of the video signal line DL is not provided above, the withstand voltage of the insulating film GI is lowered because the selection ratio of the insulating film GI in the etching of the semiconductor layer AS is not sufficient. .

<< Transparent Pixel Electrode ITO1 >> Transparent Pixel Electrode I
TO1 forms one of the pixel electrodes of the liquid crystal display section. The transparent pixel electrode ITO1 is connected to the source electrode SD1 of the thin film transistor TFT. This transparent pixel electrode ITO1
Is composed of a first conductive film d1, and the first conductive film d1 is a transparent conductive film (In
dium-Tin-Oxide ITO (nesa film), 1000-
With a thickness of 2000Å (about 1400Å in this embodiment)
It is formed.

<< Source Electrode SD1, Drain Electrode SD
2 >> Each of the source electrode SD1 and the drain electrode SD2 has a second conductive film d2 that colors the N (+) type semiconductor layer d0.
And a third conductive film d3 formed thereon.

The second conductive film d2 is a chromium (Cr) film formed by sputtering and is formed to a thickness of 500 to 1000 Å (in this embodiment, about 600 Å). Cr film is N
It is used for the purpose of improving adhesion to the (+) type semiconductor layer d0 and preventing Al of the third conductive film d3 from diffusing into the N (+) type semiconductor layer d0 (so-called barrier layer).
As the second conductive film d2, a refractory metal (M
o, Ti, Ta, W) film, refractory metal silicide (Mo
A Si ₂ , TiSi ₂ , TaSi ₂ , WSi ₂ ) film may be used.

The third conductive film d3 is formed by sputtering Al to a thickness of 3000 to 5000 Å (400 in this embodiment).
0 Å) formed. The Al film has less stress than the Cr film and can be formed to have a thick film thickness, which reduces the resistance values of the source electrode SD1, the drain electrode SD2 and the video signal line DL, and is caused by the scanning signal line GL. It has the function of ensuring that you can climb over steps (step coverage).

The source electrode SD1 and the drain electrode S
D2 is a laminated film of the second conductive film d2 and the third conductive film d3, but in the case of a relatively small liquid crystal display device, it may be only the second conductive film which is a refractory metal such as a Cr film. In that case, it is necessary to increase the film thickness to about 1800Å.

After patterning the second conductive film d2 and the third conductive film d3 with the same mask pattern, N (+) is used with the same mask or with the second conductive film d2 and the third conductive film d3 as a mask. The type semiconductor layer d0 is removed. That is, in the N (+) semiconductor layer d0 remaining on the i-type semiconductor layer AS, the portions other than the second conductive film d2 and the third conductive film d3 are removed by self-alignment. At this time, the N (+) type semiconductor layer d0 is etched so that the entire thickness thereof is removed, so that the surface of the i type semiconductor layer AS is also slightly etched. You can control it.

<Video Signal Line (Data Line) DL> The video signal line DL is composed of the second conductive film d2 and the third conductive film d3 in the same layer as the source electrode SD1 and the drain electrode SD2, or the second conductive film d2. It is composed of only the conductive film d2.

<< Protective Film PSV1 >> Thin Film Transistor TF
A protective film PSV1 is provided on the T and the transparent pixel electrode ITO1. The protective film PSV1 is formed mainly for protecting the thin film transistor TFT from moisture, and a film having high transparency and good moisture resistance is used.

The protective film PSV1 is formed of, for example, a silicon oxide film or a silicon nitride film formed by a plasma CVD apparatus, and has a film thickness of about 1 μm. The protective film is generally formed by a vacuum apparatus such as plasma CVD, but this improves throughput when formed by coating an organic material such as epoxy resin.

The protective film PSV1 is formed on the pixel electrode I as shown in FIG. 1 which is a 1-1 cross section of FIG.
It can be confirmed that the slit-shaped opening SH that exposes the contour of TO1 is formed.

<< Light-shielding film BM >> Second transparent glass substrate SU
A light shielding film BM is provided on the B2 side so that external light or backlight light does not enter the i-type semiconductor layer AS. The closed polygonal outline of the light-shielding film BM shown in FIG.
The inside thereof shows an opening in which the light shielding film BM is not formed. The light-shielding film BM is formed of, for example, an aluminum film or a chrome film having a high light-shielding property against light. In this embodiment, the chrome film is formed by sputtering to a thickness of about 1300 Å.

Therefore, i of the thin film transistor TFT
At least a so-called channel region between the source electrode SD1 and the drain electrode SD2 in the type semiconductor layer AS is sandwiched by the upper and lower light-shielding films BM and the large scanning signal line GL so that external natural light or backlight light does not hit. The light-shielding film BM is formed in a lattice shape around each pixel (so-called black matrix), and the effective display area of one pixel is partitioned by this lattice. Therefore, the contour of each pixel is made clear by the light shielding film BM, and the contrast is improved. That is, the light blocking film BM has two functions of blocking the i-type semiconductor layer AS and serving as a black matrix.

Since the edge portion of the transparent pixel electrode ITO on the base side in the rubbing direction (the lower right portion in FIG. 2) is also shielded by the light shielding film BM, even if a domain is generated in the above portion, the domain cannot be seen. The characteristics do not deteriorate.

The light-shielding film BM is also formed in a frame shape in the peripheral portion of the liquid crystal display panel, and its pattern is formed continuously with the pattern of the matrix portion shown in FIG. The light-shielding film BM in the peripheral portion is extended to the outside of the seal portion SL and urges leak light such as reflected light caused by a mounting machine such as a personal computer to enter the matrix portion. On the other hand, the light-shielding film BM is held inside by about 0.3 to 1 mm from the edge of the substrate SUB2.
Is formed so as to avoid the cutting area.

The color filter FIL can be formed as follows. First, the second transparent glass substrate SUB2
The dyeing base material such as acrylic resin is removed from the surface of the. Then, the dyeing base is dyed with a red dye and a fixing process is performed to form a red filter R. Next, the green filter G and the blue filter B are sequentially formed by performing the same process.

<< Protective Film PSV2 >> The protective film PSV2 is provided to prevent the dye of the color filter FIL from leaking to the liquid crystal LC. The protective film PSV2 is formed of a transparent resin material such as acrylic resin or epoxy resin.

<< Common Transparent Pixel Electrode ITO2 >> The common transparent electrode ITO2 (see FIGS. 1 and 3) is a transparent pixel electrode ITO provided for each pixel on the first transparent glass substrate SUB1 side.
1. The optical state of the liquid crystal LC faces each pixel electrode IT.
It changes in response to a potential difference (electric field) between O1 and the common transparent pixel electrode ITO2. A common voltage Vcom is applied to the common transparent pixel electrode ITO2. In this embodiment, the common voltage Vcom is the video signal line D
It is set to an intermediate DC potential between the minimum level drive voltage Vdmin applied to L and the maximum level drive voltage Vdmax, but when it is desired to reduce the power supply voltage of the integrated circuit used in the video signal drive circuit to about half, The AC voltage may be applied.

<< Structure of Storage Capacitance Element Cadd >> The transparent pixel electrode ITO1 is formed so as to overlap the adjacent scanning signal line GL at the end opposite to the end connected to the thin film transistor TFT. As is clear from FIG. 4, this superposition is performed by using one of the laminated electrodes of the second conductive film d2 and the third conductive film d3 which are the materials of the source electrode SD1 and the drain electrode SD2 connected to the transparent pixel electrode ITO1. The electrode PL2 is used, and the adjacent scanning signal line GL is connected to the other electrode D.
A storage capacitor element Cadd to be L1 is formed. The dielectric film of the storage capacitor Cadd is a thin film transistor TF.
An anodized film AOF used as a gate insulating film of T,
It is composed of an insulating film GI, an i-type semiconductor layer AS, and an N (+)-type semiconductor layer d0. As a result, the intersection of the gate electrode (scanning signal line GL) and the drain electrode SD2, the intersection of the scanning signal line GL and the video signal line DL, and the scanning signal line G.
The anodic oxide film AOF and the insulating film G are provided between the electrodes in the vertical direction at the intersection of L and the source electrode and the intersection of the above Cadd.
The I, i-type semiconductor layer AS and the N (+)-type semiconductor layer d0 are stacked. This means that the insulating film G continuously formed by the plasma CVD method between the electrodes of the storage capacitor element.
Since the I, i-type semiconductor layer AS and the N (+)-type semiconductor layer d0 are formed without being removed by etching, short-circuit defects (point defect mode) are reduced.

<< Antireflection by Video Signal Line DL >> In the liquid crystal display module MDL of this embodiment, as shown in FIG. 5, the backlight BL is arranged on the side of the second transparent glass substrate SUB2 forming the liquid crystal display panel PNL. The first transparent glass substrate SUB1 on which the thin film transistor TFT, the video signal line DL and the like are formed is arranged on the user side.
An active matrix type liquid crystal display panel PNL having an inverted stagger structure in which a gate electrode, a gate insulating film, a semiconductor layer for channel formation, and source / drain electrodes are sequentially formed on a transparent glass substrate SUB1 as shown in FIG. Further, between the video signal line DL and the transparent glass substrate SUB1, the i-type semiconductor layer AS made of amorphous silicon and the gate insulating film GI are patterned in a shape along the video signal line DL. The gate insulating film GI is formed between the i-type semiconductor layer AS and the transparent glass substrate SUB1,
The i-type semiconductor layer AS and the gate insulating film GI are wider than the video signal line DL (d3, d2) and have the same pattern shape. The i-type semiconductor layer AS and the gate insulating film GI follow the pattern shape of the video signal line DL except the location of the thin film transistor TFT. ing. The amorphous silicon semiconductor layer has a dark brown color and has large light absorption. For example, in FIG. 1, external incident light 1 and 2 are absorbed by the i-type semiconductor layer AS and reflected as shown by a broken line.
Do not pass through. Thus, by interposing the i-type semiconductor layer AS between the second conductive film d2 made of Cr having a high reflectance and forming the video signal line DL, and the transparent glass substrate SUB1, the outside of the display screen side can be obtained. Incident light is reflected to the outside (user side) by the video signal line DL, the screen becomes difficult to see (looks like a mirror), the contrast (brightness difference between black and white) deteriorates, and the display quality deteriorates. Can solve the problem. That is, the contrast is improved,
Image quality is improved. Further, it is not necessary to perform expensive anti-reflecting coating on the polarizing plate POL1 for preventing deterioration of display quality due to reflected light on the display screen side, and the manufacturing cost can be reduced. Furthermore, i is placed under the entire line of the video signal line DL.
By providing the type semiconductor layer AS, conventionally, the scanning signal G
It is possible to reduce the occurrence of disconnection of the video signal line DL at the step-over portion of the i-type semiconductor layer AS which is partially provided at the intersection of the L and the video signal line DL to prevent short-circuiting between them, and therefore, the manufacturing cost is reduced. It can be reduced. In addition, the transparent electrode IT
When O1 overlaps the i-type semiconductor layer AS and the gate insulating film GI, a parasitic capacitance occurs between the video signal line DL and the transparent pixel electrode ITO1, but in the present embodiment, as shown in FIG. Since the electrode ITO1 does not overlap the i-type semiconductor layer AS and the gate insulating film GI, parasitic capacitance does not occur. An N (+) type semiconductor layer d0 is formed between the video signal line DL and the i type semiconductor layer AS.
The i-type semiconductor layer AS and the gate insulating film GI formed between the video signal line DL and the transparent glass substrate SUB1 are formed in the same step as the channel-forming i-type semiconductor layer AS and the gate insulating film GI of the thin film transistor TFT, respectively. In, the same material is used. Therefore, the number of manufacturing steps does not increase.

Further, according to the present embodiment, as shown in FIG. 1, when viewed from the user side, the i-type semiconductor layer AS covers the video signal line DL with a certain degree of alignment, so that both pixels are covered. It is possible to prevent the occurrence of display unevenness due to the variation in each alignment.

<< Manufacturing Method >> Next, a manufacturing method of the above-mentioned liquid crystal display device on the first transparent glass substrate SUB1 side will be described with reference to FIGS. In the figure,
The table of contents in the center is an abbreviation of the process name, the left side shows the pixel portion shown in FIG. 3, and the right side shows the flow of processing seen in the sectional shape near the gate terminal. Except for Process B and Process D, Process A to Process G are divided according to each photo (photo) process, and each cross-sectional view of each process shows the stage after processing after photo processing and removal of photoresist. ing. In the present description, the above-mentioned photographic (photo) processing means a series of operations from application of photoresist to selective exposure using a mask to development thereof, and repeated description will be omitted. Hereinafter, description will be given according to the divided steps.

Step A, FIG. 6 After the silicon oxide films SIO are provided on both surfaces of the first transparent glass substrate SUB1 made of 7059 glass (trade name) by dip processing, baking is performed at 500 ° C. for 60 minutes. Although this SIO film is formed in order to alleviate the surface irregularities of the glass substrate SUB1, this step can be omitted if the irregularities are small. Al-Ta, A with a film thickness of 2800Å
The second conductive film g1 made of l-Ti-Ta, Al-Pd, or the like.
Are selectively etched.

Step B, FIG. 6 After directly drawing the resist (after forming the above-described anodic oxidation pattern AO), 3% tartaric acid was used to pH 6.25 ± by an ammonia.
The solution adjusted to 0.05 is 1: 1 with ethylene glycol solution.
The substrate SUB1 is dipped in an anodizing solution composed of the solution diluted to 9 to adjust the formation current density to 0.5 mA / cm2 (constant current formation). Next, anodic oxidation is performed until the formation voltage 125 V required to obtain a predetermined Al ₂ O ₃ film thickness is reached. After that, it is desirable to hold this state for several tens of minutes (constant current formation). This is important for obtaining a uniform Al ₂ O ₃ film. Thereby, the conductive film g1 is anodized, and the anodic oxide film A having a film thickness of 1800Å is self-aligned on the scanning signal line (gate line) GL and on the side surface.
OF is formed and becomes a part of the gate insulating film of the thin film transistor TFT.

Step C, FIG. 6 A conductive film d1 made of an ITO film having a film thickness of 1400Å is provided by sputtering. After the photo-treatment, the conductive film d1 is selectively etched with a mixed acid solution of hydrochloric acid and nitric acid as an etching solution to form the uppermost layers of the gate terminal GTM and the drain terminal DTM and the transparent pixel electrode ITO1.

Step D, FIG. 7 Ammonia gas, silane gas, and nitriding gas are introduced into the plasma CVD apparatus to provide a pressure-reducing film 2000 Å SiN nitride film, and silane gas and hydrogen gas are introduced into the plasma CVD apparatus to obtain a film thickness of 2000 Å After providing the i-type amorphous Si film of
Hydrogen gas and phosphine gas are introduced into a plasma CVD apparatus to form an N (+) type amorphous Si film having a film thickness of 300 Å. This film formation is continuously performed by changing the reaction gas in the same CVD apparatus.

Step E, FIG. 7 After photo processing, SF ₆ and CC are used as dry etching gas.
Use l ₄ N (+) type amorphous Si film, i-type amorphous S
Etch the i film. Subsequently, etching the nitride Si film using SF _6. The N (+) type amorphous Si film, the i type amorphous Si film and the Si nitride film may be continuously etched with SF ₆ gas.

Thus, the following effects can be obtained by continuously etching the three-layered CVD film with the gas containing SF ₆ as a main component. That is, the etching rate for the SF ₆ gas increases in the order of the N (+) type amorphous Si film, the i type amorphous Si film, and the Si nitride film. Therefore, when the N (+) type amorphous Si film is completely etched and the i-type amorphous Si film is started to be etched, the upper N (+) type amorphous Si film is side-etched, resulting in the i-type. Amorphous Si film is about 70
Processed into a taper of degree. When the etching of the i-type amorphous Si film is completed and the SI nitride film starts to be etched, the upper N (+)-type amorphous Si film and the i-type amorphous Si film are side-etched in this order. Specifically, the i-type amorphous Si film is tapered by about 50 degrees and the silicon nitride film is tapered by 20 degrees.
Even if the source electrode SD1 is formed on the taper shape, the probability of disconnection is significantly reduced. N
The taper angle of the (+) type amorphous Si film is close to 90 degrees, but since the thickness is as thin as 300Å, the probability of disconnection at this step is very small. Therefore, the N (+) type amorphous Si film, i
Strictly speaking, the plane patterns of the amorphous silicon film and the silicon nitride film are not the same pattern, and the cross section is a forward taper shape.
The (+)-type amorphous Si film, the i-type amorphous Si film, and the Si nitride film have a large pattern in this order.

Step F, FIG. 8 A second conductive film d2 made of Cr having a film thickness of 6000Å is provided by sputtering, and Al having a film thickness of 4000Å is provided.
A third conductive film d3 made of -Pd, Al-Si, Al-Ta, Al-Ti-Ta or the like is provided by sputtering. After the photo-treatment, the third conductive film d3 is etched with the same liquid as the process A, and the second conductive film d2 is etched with a second cerium ammonium nitrate solution to form the video signal line DL, the source electrode SD1 and the drain electrode SD2. To do.

Here, in this embodiment, as shown in step E, an N (+) type amorphous Si film, an i type amorphous Si film, a silicon nitride film
Since the film has a forward taper, it is possible to form only the second conductive film d2 in a liquid crystal display device in which the tolerance of the resistance of the video signal line DL is large.

Next, SF ₆ and C are added to the dry etching apparatus.
By introducing Cl ₄ and etching the N (+) type amorphous Si film, the N (+) type semiconductor layer d0 between the source and the drain is selectively removed.

Step G, FIG. 8 Ammonia gas, silane gas, and nitrogen gas are introduced into the plasma CVD apparatus to form a Si nitride film having a thickness of 1 μm. After the photo-treatment, the protective film PSV1 is formed by etching using SF ₆ as a dry etching gas. As the protective film, not only an SiN film formed by CVD but also an organic material can be used.

Next, after forming the protective film PSV1 in this way, in the present embodiment, the steps shown in FIGS. 9 to 12 are performed. This is because the pixel electrode ITO1 and the wiring layer (scanning signal line GL) adjacent to the pixel electrode ITO1.
Alternatively, a conductive foreign substance (including the residue of the semiconductor layer AS) is attached between the pixel electrode ITO and the video signal line DL).
This is because of an attempt to prevent the occurrence of so-called point defects in the manufacturing stage.

Here, FIGS. 9 to 12 are different from the drawings showing the above-mentioned steps, and will be described based on the section 1-1 of FIG.

Step H, FIG. 9 FIG. 9 is a diagram after formation of the protective film PSV1.
Here, in the worst case, the pixel electrode ITO1 has a foreign substance A (remaining substance of the semiconductor layer AS) made of a semiconductor between the pixel electrode ITO1 and the video signal line DL adjacent to the right side in the figure, and the video signal line adjacent to the left side in the figure. It is assumed that a foreign substance B made of a metal (for example, a residue of the conductive layers d2 and d3) is adhered to the DL and causes an electrical short circuit with the video signal line DL.

At this point, the manufacturer does not need to be aware of the presence of this foreign substance. This is because the following steps are performed on the premise of the presence of foreign matter.

Step I, FIG. 10 The protective film PSV1 is selectively etched, for example, to form the slit-shaped openings SH in the pattern shown in FIG. In this case, the removal of part of the protective film PSV1 associated with the formation of the slit-shaped opening SH directly removes part of the foreign material A, and an electrical short circuit between the pixel electrode ITO1 and the scanning signal line DL due to the foreign material A is avoided. become able to. This is because the etchant required to remove the foreign substance A made of a semiconductor is the same as that required to remove the protective film PSV1.

In this case, since the foreign matter B is still present, the electrical short circuit between the pixel electrode ITO1 and the scanning signal line DL has not been completely eliminated.

Step J, FIG. 11 At this stage, the point defect inspection of the pixel electrode ITO1 is performed,
It will be recognized that the foreign matter B remains.

Then, the position of the foreign substance B is confirmed by using, for example, a microscope for exclusive use thereof, and the foreign substance B is detected by the laser beam L.
Incinerate and remove with L. At this time, the foreign matter removal using the laser beam can be directly performed without forming a special atmosphere.

In this case, since the slit-shaped opening SH is still formed in the protective film PSV1, it is possible to avoid the complexity of arranging the protective film PSV1 with an opening and performing laser irradiation.

Step K, FIG. 12 Thus, the pixel electrode ITO1 and this pixel electrode ITO1 are formed.
It is possible to completely remove the foreign matter (the foreign matter A made of a semiconductor and the foreign matter B made of a metal) remaining between the pixel electrode ITO1 and the wiring layer adjacent to the pixel electrode ITO1.
It becomes possible to eliminate the so-called point defect.

According to the manufacturing method described above, the pixel electrode ITO1 and the wiring layer arranged adjacent to the pixel electrode are made of the semiconductor left over when the thin film transistor TFT is formed so as to be connected to each other. Even if the foreign matter A is adhered, the foreign matter A is removed by forming the slit-shaped opening SH in the protective film PSV1.

This is because the foreign material A is also removed at the same time by the opening forming means (for example, etching) of the protective film.

Since the foreign material A can be removed in this way, the pixel electrode ITO1 can be driven normally.
The occurrence of so-called point defects can be prevented.

Further, when a conductor made of a foreign substance other than a semiconductor is attached so as to connect the pixel electrode ITO1 and a wiring layer arranged adjacent to the pixel electrode ITO1, particularly, the protective film PSV1 It becomes possible to incinerate and remove it by using the laser beam as it is, without going through the step of removing.

In the above-mentioned embodiment, the protective film PSV1 is provided with the slit-shaped opening SH so as to expose the contour of the pixel electrode ITO1.

However, as shown in FIG. 13, the pixel electrode I
The same effect can be achieved by forming the opening OH that exposes TO1 including its contour. In this case, most of the image electrode ITO1 is exposed from the protective film PSV1, so that it is possible to improve the light transmittance as well.

FIG. 14 is a sectional view taken along the line 14-14 in FIG.

In any of the above-described embodiments, the contour of the pixel electrode ITO1 is exposed. This is because the pixel electrode ITO1 is a transparent glass substrate SU.
It is effective when it is formed directly on B1.

That is, for example, as shown in FIG.
If the pixel electrode ITO1 is formed on the upper surface of the insulating film GI and the slit-shaped opening SH is formed as shown in FIG. 10 as it is, the etching proceeds to the insulating film GI. become.

This means that the peripheral portion of the pixel electrode ITO1 is etched in a shape in which the insulating film GI immediately thereunder is hollowed, and the peripheral portion of the pixel electrode ITO1 is overhung as if the eaves were protruding. .

Therefore, the pixel electrode ITO1 is thus formed.
15 is formed on the insulating film GI, as shown in FIG. 15, a slit-shaped opening SH is formed in the protective film PSV1 in at least a part of a line surrounding the pixel electrode ITO1 outside the contour thereof. Will be preferred.

[0099]

As is apparent from the above description,
According to the method for manufacturing a liquid crystal display substrate of the present invention, it is possible to prevent the occurrence of so-called point defects.

[Brief description of drawings]

1 is a cross-sectional view showing an embodiment of a liquid crystal display substrate to which a manufacturing method of the present invention is applied, and corresponds to a 1-1 cross section in FIG.

FIG. 2 is a cross-sectional view showing an embodiment of a liquid crystal display substrate to which the manufacturing method of the present invention is applied.

FIG. 3 is a cross-sectional view taken along line 3-3 of FIG.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG.

FIG. 5 is an exploded perspective view showing an embodiment of a liquid crystal display device to which the manufacturing method of the present invention is applied.

FIG. 6 is an explanatory view showing an embodiment of the manufacturing method of the present invention,
It is the figure which showed process AC.

FIG. 7 is an explanatory view showing an embodiment of the manufacturing method of the present invention,
It is the figure which showed process D-E.

FIG. 8 is an explanatory view showing an embodiment of the manufacturing method of the present invention,
It is the figure which showed process F-G.

FIG. 9 is an explanatory view showing an embodiment of the manufacturing method of the present invention,
It is the figure which showed process H.

FIG. 10 is an explanatory view showing an embodiment of the manufacturing method of the present invention, and is a drawing showing a step I.

FIG. 11 is an explanatory view showing an embodiment of the manufacturing method of the present invention, showing a step J.

FIG. 12 is an explanatory view showing an embodiment of the manufacturing method of the present invention, showing a step K.

FIG. 13 is an explanatory view showing another embodiment of the manufacturing method of the present invention.

14 is a diagram showing a 14-14 cross section of FIG. 13;

FIG. 15 is an explanatory view showing another embodiment of the manufacturing method of the present invention.

[Explanation of symbols]

SUB: transparent glass substrate, ITO1: pixel electrode, P
SV1 ... Protective film, TFT ... Thin film transistor (semiconductor switching element), SH ... Slit-like opening, OH
…… Aperture.

Claims (4)

[Claims] 1. A semiconductor switching element and a pixel electrode are formed on at least a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and cover the semiconductor switching element and the pixel electrode. A method for manufacturing a liquid crystal display substrate in which a protective film is formed by forming a slit-shaped opening for exposing at least part of the contour of the pixel electrode in the protective film after forming the protective film. A method of manufacturing a liquid crystal display substrate, comprising: 2. A semiconductor switching element and a pixel electrode are formed on at least a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and cover the semiconductor switching element and the pixel electrode. In the method for manufacturing a liquid crystal display substrate, wherein the pixel electrode is formed on an insulating film, the pixel electrode is formed on the protective film after the protective film is formed. A method of manufacturing a liquid crystal display substrate, comprising a step of forming a slit-shaped opening reaching at least the insulating film on at least a part of a line surrounding the contour. 3. A semiconductor switching element and a pixel electrode are formed on at least a liquid crystal side surface of one of the transparent substrates arranged to face each other with a liquid crystal interposed therebetween, and cover the semiconductor switching element and the pixel electrode. In the method for manufacturing a liquid crystal display substrate in which a protective film is formed, a step of forming an opening that exposes the pixel electrode including the contour thereof in the protective film after forming the protective film is included. A method for manufacturing a characteristic liquid crystal display substrate. 4. A signal line is formed adjacent to a pixel electrode, and a conductive foreign substance exists between the pixel electrode and the signal line in an opening formed in the protective film. 3. The method for manufacturing a liquid crystal display substrate according to claim 1, further comprising incinerating the foreign matter with a laser beam applied through the opening.