JPH0973100A - Production of liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the production stages of a liquid crystal display device. SOLUTION: Contact holes 122a on drain electrodes 11, contact holes 122b on common electrodes 112 and contact holes 122c on conductive light shielding films 114 are simultaneously formed and thereafter, a conductive film is deposited and patterned to simultaneously form the connecting wirings 116b of the common electrodes 112 and the conductive light shielding film 114 and pixel electrodes 116 in the case of producing an active matrix substrate 101 in a process for producing the liquid crystal display device constituted by holding liquid crystals 117 between the active matrix substrate 101 having thin-film transistors and a counter substrate 120. As a result, the electrical connection of two sets of the active matrix substrates 101 is made executable by the same stage, by which the cost is reduced, a defect rate is lowered, the yield is improved and the device is stabilized.

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 device using an active matrix substrate having a thin film switching element, and more particularly to a manufacturing technique of this active matrix substrate.

[0002]

2. Description of the Related Art In recent years, for a display device using a liquid crystal, a higher definition display image has been demanded. Among them, the so-called active matrix type display panel that uses a thin film switching element for driving an image has a large number of pixels and high gradation relatively easily compared with other types of liquid crystal display panels, and thus technological development is rapidly progressing. It is being advanced.

[0005] In general, a thin film switching element used for an active matrix type display panel has a capacity of five.
Thin-film transistors (TFTs) using amorphous silicon (a-Si) for large panels larger than inches and mainly polysilicon (p-Si) for smaller panels smaller than inches
Is used. A schematic view of a liquid crystal display panel using p-SiTFT is shown in FIG. A vertical shift register 303 and a horizontal shift register 304 are connected to a panel display circuit 305 having p-Si TFTs arranged in a matrix as switching elements, and a TV image signal sent from the video signal circuit 301 is a vertical shift register 303 and a vertical shift register 303. Display circuit 305 via horizontal shift register 304
Written to the inside pixel. Reference numeral 302 is a synchronizing circuit for timing the two shift registers 303 and 304.

The equivalent circuit of this liquid crystal panel is as shown in FIG. The pixel electrode 40 is provided at the intersection of the plurality of signal lines 401a to 401d and the plurality of scanning lines 402a to 402d.
6 is arranged, and the drain of the TFT 403 is connected to the pixel electrode. The signal line 40 is connected to the source of the TFT 403.
1a to 401d are connected, and the scanning line 402a is connected to the gate.
-402d are respectively connected. Pixel electrode 406
A video signal from the signal lines 401a to 401d is written in. The drain of the TFT 403 is also connected to a storage capacitor 404 for holding the written charge for a sufficiently long time, and the other end 405 of the electrode of the capacitor is connected to a common potential for all pixels or pixels for each row. .

The structure around the pixel electrode 406 and the TFT 403 will be outlined with reference to the schematic diagram of the panel cross section shown in FIG.

In FIG. 5, 101 is a silicon substrate, 1
Reference numeral 02 is a thick oxide film for element isolation, 103 is a silicon nitride film, and 104 is an insulating film. Reference numeral 105 is a low concentration source / drain for relaxing an electric field, 106 is a high concentration source / drain, 107 is a gate insulating layer made of, for example, a silicon oxide film, and 108 is made of, for example, n-type doped polycrystal. The two gate electrodes 108 have the same potential, and the two gate electrodes 108 are present in series between the source and the drain to form a so-called “dual gate TFT” 123. Reference numeral 109 is a 0th interlayer insulating layer, 110 is a source electrode, 111 is a drain electrode, and the source electrode 11
0 and the drain electrode 111 are the signal line 401 (not shown) and the pixel electrode 406 (reference numeral 116a in FIG. 5), respectively.
It is connected to the. 112 is a common electrode formed in the same process as the source electrode 110 and the gate electrode 111, 113
Is a first interlayer insulating layer, 114 is a conductive light-shielding film, 115 is a second interlayer insulating layer, and 116a is a pixel electrode made of a conductive film such as ITO or Al. The conductive light-shielding film 114 for blocking light to the TFT portion and the pixel electrode 116a constitute the storage capacitor 404 with the second interlayer insulating layer 115 interposed therebetween, and the conductive light-shielding film 114 is connected to the common electrode 112. Has been done. The active matrix substrate is configured as described above.

Reference numeral 120 denotes a counter substrate which is arranged so as to face the active matrix substrate having the above structure. In the case of a full-color display panel like this example, the counter substrate 120
Above is a color filter 119 using a dye or pigment.
, And a black matrix 121 of Cr or the like is formed between the pixels and on the peripheral drive circuit. In addition, a transparent counter electrode 118 common to all pixels or common to many pixels is formed on the counter substrate 120 at a position facing the pixel electrode 116a.

A liquid crystal material 117 is sealed between the active matrix substrate and the counter substrate 120.

As shown in FIG. 5, conventionally, the connection of one end 405 of the electrode of the storage capacitor 404 in FIG. 4 has been made directly between the conductive light shielding film 114 and the common electrode 112.

[0010]

In the above-mentioned conventional method,
In order to obtain the connection between the conductive light-shielding film 114 and the common electrode 112, after forming a first interlayer insulating layer 113 such as silicon nitride, resist patterning and etching for forming a contact hole at a portion 501 in FIG. 5 are performed. After going
A conductive light-shielding film 114 is deposited and patterned, and then
In order to obtain the connection between the pixel electrode 116a and the gate electrode 111, after forming the second interlayer insulating layer 115 such as silicon oxide, resist patterning and etching for forming a contact hole at a portion 122a in FIG. 5 were performed. After that, the pixel electrode 116a is deposited and patterned.

As described above, conventionally, resist patterning and etching are performed twice in order to obtain two sets of electrical connections in the active matrix substrate, so that reliability and yield are inevitably increased due to an increase in the number of steps. However, there is a problem that the manufacturing cost is increased.

The present invention has been made in view of the above-mentioned problems of the prior art,
It is an object of the present invention to reduce cost and improve reliability and yield by reducing the manufacturing process of an active matrix substrate used for a liquid crystal display device.

[0013]

The constitution of the present invention made to achieve the above object is as follows.

That is, according to the present invention, a liquid crystal display device in which a liquid crystal is sandwiched between an active matrix substrate having a thin film transistor corresponding to an intersection of a signal line and a scanning line, and a counter substrate facing the active matrix substrate. In the manufacturing method of (1), the step of manufacturing the active matrix substrate includes the steps of (1) forming a first insulating layer on the substrate surface on which the main electrode and the common electrode of the thin film transistor are formed; Depositing a conductive film and patterning it into a desired shape; (3) forming a second insulating layer; (4) a contact hole on the main electrode;
A step of simultaneously forming a contact hole on the common electrode and a contact hole on the first conductive film; and (5) depositing a second conductive film and patterning it into a desired shape. And a step of electrically connecting the common electrode and the first conductive film and forming a pixel electrode electrically connected to the main electrode. .

According to the present invention, two sets of electrical connections in the active matrix substrate, that is, the first conductive film serving as a conductive light-shielding film and the common electrode, and the main electrode (drain electrode) of the thin film transistor and the pixel electrode are provided. Electrical connection with
It is possible to perform the resist patterning and etching once.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the first conductive film corresponds to the above-mentioned conductive light-shielding film 114.
It is preferable that the first conductive film has a laminated structure, and thus the connection portion with the wiring for connecting with the common electrode 112 can be ohmic-connected.

Further, it is preferable that the upper layer film of the first conductive film having the above-mentioned laminated structure functions as an etching stopper layer at the time of forming a contact hole, and the stability of a semiconductor device manufactured by this is improved. be able to.

Further, by using aluminum, titanium, chromium or an alloy thereof as the main component of the etching stopper layer, an extremely high effect of etching stop is exhibited.

By using a transparent conductive film as the second conductive film, it can be applied to a transmission type liquid crystal display device.

[0020]

EXAMPLES The present invention will be described in detail below with reference to examples.

(Embodiment 1) FIG. 1 is a schematic sectional view of a panel portion of a liquid crystal display device of this embodiment. In the figure, the same reference numerals as those in FIG. 5 are equivalent members.

Reference numeral 101 is a silicon substrate, 102 is a thick oxide film for element isolation, 103 is a silicon nitride film formed by a low pressure CVD method having a tensile stress with respect to the silicon substrate 101. By using this film, a membrane is formed. Wrinkles and slack can be suppressed.

When the refractive index is n, the film thickness d of the silicon nitride film 103 is a conditional expression for antireflection; nd = Nλ / 2
It is properly selected according to (N is a natural number). The wavelength λ is, for example, 550 nm, which has the highest relative luminous efficiency of the human eye.
It is good to choose the degree. According to the above antireflection conditional expression, the silicon nitride film thickness d is, for example, 2700Å or 4200Å
Becomes

An insulating film 104 serving as an etching stopper layer of polysilicon was deposited on the silicon nitride film 103. The insulating film 104 is, for example, NSG or BPSG formed by the TEOS-CVD method, or a thermal oxide film formed on the surface of the silicon nitride film by thermal oxidation.

In addition, a high concentration source / drain 10
6. Low-concentration source / drain 10 for relaxing the electric field
5. A dual gate TFT composed of a gate insulating film 107 made of a silicon oxide film, two gate electrodes made of n-type doped polycrystalline silicon, etc. was manufactured.

The 0th interlayer insulating layer 109 is TEOS-C.
It is composed of BPSG, NSG, PSG by the VD method or a laminated film thereof.

The source electrode 110, the gate electrode 111, the common electrode 112 and the matrix wiring (not shown) are laminated films composed of aluminum films (110a, 111a, 112a) and titanium films (110b, 111b, 112b), respectively. This facilitates ohmic connection with the pixel electrode 116a.

The first interlayer insulating layer 113 is made of silicon oxide formed by the CVD method, BPSG, NSG, PSG.
Etc.

Conductive light-shielding film 1 for blocking light to the TFT section
Reference numeral 14 is, for example, TiN, Ti, etc., and
A storage capacitor is formed by sandwiching the second interlayer insulating layer 115 together with 6a.

The second interlayer insulating layer 115 serves as a hydrogen supply source to the TFT portion and is composed of, for example, a silicon nitride film formed by a plasma CVD method.

As described above, the conductive light-shielding film 114, which is one end of the capacitance electrode, is connected to the common electrode 112,
The pixel electrode 116a is connected to the drain electrode 111, and the most important feature of the present invention is the step of making this electrical connection. The method in this embodiment will be described below.

First, a contact hole 122a on the drain electrode 111, a contact hole 122b on the common electrode 112, and a contact hole 122c on the conductive light shielding film 114 are simultaneously formed by etching.

Since the contact hole 122c needs to be stopped on the conductive light-shielding film 114, it is necessary to select an etching condition having a high selection ratio between the second interlayer insulating layer 115 and the conductive light-shielding film 114. For example, when reactive ion etching using CF ₄ and CHF ₃ as etching gas is used as the etching method, the gas composition ratio CF
_The conditions may be such as ₄ : CHF ₃ = 1: 4 with a large amount of deposition gas.

Next, a conductive film to be the pixel electrode 116a and a connection wiring 116b for connecting the conductive light-shielding film 114 and the common electrode 112 is deposited. This conductive film is made of, for example, ITO formed by a sputtering method. This conductive film was patterned to form pixel electrodes 116a and connection wirings 116b. Here, the conductive light-shielding film 1
14 and the connection wiring 116b could be ohmic-connected. The conductive light-shielding film 116b is connected to the same common electrode 112 and set to the same potential for all pixels or pixels in each row direction.

In order to mount the active matrix substrate manufactured as described above as a liquid crystal display device, the counter substrate 120 is arranged in parallel and opposed thereto. In this embodiment, since a full-color display panel is constructed, the counter substrate 12
0, color filter 119 using dye or pigment
And a black matrix 121 of Cr or the like was formed on the drive circuit between the pixels and on the periphery. In addition, the counter substrate 12
0, a transparent counter electrode 118 common to all pixels or common to many pixels at a position facing the pixel electrode 116a.
Was formed.

Then, a liquid crystal material 117 is enclosed between the active matrix substrate and the counter substrate 120 to form a liquid crystal panel.

In this embodiment, two sets of electrical connections on the active matrix substrate, that is, the conductive light-shielding film 114 and the common electrode 112, and the drain electrode 111 of the TFT and the pixel electrode 116a are electrically connected in the same step. As a result, the number of steps is reduced, the cost is reduced, the defect rate is reduced, the yield is improved, and the liquid crystal display device is stabilized.

(Embodiment 2) When the contact holes 122a, 122b, 122c are simultaneously formed by the method described in Embodiment 1, the conductive light-shielding film 114 and the second interlayer insulating layer 11 are formed.
By further increasing the etching selection ratio of 5, the stability of the semiconductor device according to the present invention can be further improved. This embodiment realizes this,
This will be described with reference to the schematic cross-sectional view of the panel portion of the liquid crystal display device of FIG. In the figure, the same reference numerals as those in FIGS. 5 and 1 denote the same members.

In FIG. 2, the TFT section, the counter substrate, the liquid crystal section and the like have the same configuration as that of FIG. 1 according to the first embodiment. However, on the conductive light-shielding film 114, for example, CF ₄
In dry etching using CHF ₃ and CHF ₃ as an etching gas, an etching stopper layer 201 having a very high selection ratio with respect to the second interlayer insulating layer 115, for example, aluminum, chromium, or an alloy thereof is deposited.

When the contact holes 122a, 122b, 122c are simultaneously dry-etched, the etching is stopped at the 122c portion due to the high selection ratio on the etching stopper layer 201. After this dry etching, by wet etching with phosphoric acid or the like, only the etching stopper layer 201 in the 122c portion is removed, and the conductive light-shielding film 114 is removed.
To expose. Then, a conductive film is deposited in the same manner as in Example 1 and patterned into a desired shape to form the pixel electrode 116a and the conductive light-shielding film 114.
And the connection wiring 116b between the common electrode 112 and the common electrode 112 is formed.

According to the method of this embodiment, the cost can be reduced by reducing the number of steps as in the first embodiment, and
The defect rate was lowered, the yield was improved, and the liquid crystal display device was stabilized.

[0042]

As described above, according to the present invention,
Two sets of electrical connections in the manufacturing process of the active matrix substrate, that is, a first conductive film serving as a conductive light-shielding film and a common electrode, and a main electrode (drain electrode) of a thin film transistor and a pixel electrode are electrically connected. It is possible to perform the process with one-time resist patterning and etching, and the cost can be reduced by reducing the process,
The defect rate is reduced, the yield is improved, and the device is stabilized.

[Brief description of drawings]

FIG. 1 is a schematic partial cross-sectional view of a panel of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a schematic partial cross-sectional view of a panel of a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is a schematic view showing an example of a conventional liquid crystal display panel.

FIG. 4 is a schematic diagram showing an example of an equivalent circuit of the liquid crystal display panel of FIG.

FIG. 5 is a schematic partial cross-sectional view of a liquid crystal display panel configured using a conventional method.

[Explanation of symbols]

 101 Silicon Substrate 102 Oxide Film 103 Silicon Nitride Film 104 Insulating Film 105 Low Concentration Source / Drain 106 High Concentration Source / Drain 107 Gate Insulating Film 108 Gate Electrode 109 0th Layer Insulating Layer 110 Source Electrode 111 Drain Electrode 112 Common Electrode 113th First interlayer insulating layer 114 Conductive light-shielding film (first conductive film) 115 Second interlayer insulating layer 116a Pixel electrode (second conductive film) 116b Connection wiring (second conductive film) 117 Liquid crystal material 118 Transparent Counter Electrode 119 Color Filter 120 Counter Substrate 121 Black Matrix 122a-c Contact Hole 123 TFT 201 Etching Stopper Layer 301 Video Signal Circuit 302 Synchronous Circuit 303 Vertical Shift Register 304 Horizontal Shift Register 305 Panel Display Road 401a~d signal lines 402a~d scanning lines 403 TFT 404 storage capacitor 406 pixel electrode 501 contact hole

Claims (5)

[Claims] 1. An active matrix substrate having thin film transistors corresponding to intersections of signal lines and scanning lines, and a counter substrate facing the active matrix substrate,
In a method of manufacturing a liquid crystal display device in which liquid crystal is sandwiched, in the manufacturing process of the active matrix substrate, (1) a first insulating layer is formed on a substrate surface on which a main electrode and a common electrode of the thin film transistor are formed. And (2) depositing a first conductive film and patterning it into a desired shape, (3) forming a second insulating layer, and (4) contacting on the main electrode. Forming a hole, a contact hole on the common electrode, and a contact hole on the first conductive film at the same time, and (5) depositing a second conductive film into a desired shape. Patterning to electrically connect the common electrode and the first conductive film and to form a pixel electrode electrically connected to the main electrode. Production method. 2. The method of manufacturing a liquid crystal display device according to claim 1, wherein the first conductive film has a laminated structure. 3. The liquid crystal display device according to claim 2, wherein the upper layer film of the first conductive film having the laminated structure functions as an etching stopper layer when forming a contact hole. Method. 4. The method of manufacturing a liquid crystal display device according to claim 3, wherein the main component of the etching stopper layer is aluminum, titanium, chromium, or an alloy thereof. 5. The method of manufacturing a liquid crystal display device according to claim 1, wherein the second conductive film is a transparent conductive film.