JP2001083545A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve yield and to attain low cost by using a wiring film having excellent process stability. SOLUTION: A metallic film formed by adding Cr and Ti to an alloy consisting essentially of at least Mo and W is used as at least one constituting layer among gate wiring and data wiring of a liquid crystal display device. The wiring of 0.5 to 30 wt.% W composition range is used. The wiring of 0.5 to 20 wt.% Cr composition range is used. The wiring of 0.5 to 15 wt.% Ti composition range is used. The liquid crystal display device of high yield and low cost can be provided by using Mo-W-Cr film or Mo-W-Ti film of this invention as a wiring material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an active matrix type liquid crystal display (TFT-LCD) driven by a thin film transistor (TFT).

[0002]

2. Description of the Related Art The market for a thin film transistor driven liquid crystal display (TFT-LCD) has been expanding as an image display device which can be made thinner, lighter and more precise than a conventional cathode ray tube. TFT-LCD refers to a gate wiring, a data wiring, a thin film transistor formed near an intersection of the gate wiring and the data wiring, a pixel electrode connected to the thin film transistor, a gate insulating film, and an insulating protective film formed on a glass substrate. , A counter substrate, and a liquid crystal layer sandwiched between the glass substrate and the counter substrate. With the recent increase in the size and definition of the TFT-LCD screen, demands for wiring resistance reduction, processing characteristics, and the like have been increasing. A metal film is generally used for the gate wiring and the data wiring.
As an example of applying an o-alloy wiring material, Japanese Unexamined Patent Publication No. Hei 6-31781 using a Mo-W alloy that can be processed with an Al etching solution is used.
Japanese Patent Application Laid-Open No. 10-163463 is known as Japanese Patent Application Publication No. 4-163463 as an example in which a multilayer film made of Al and Mo is applied.

[0003]

As TFT-LCDs become larger and have higher definition, requirements for wiring materials such as workability, low resistance and glass adhesion continue to be strict. In terms of manufacturing process, TFT-LCD is 600mm
Multiple thin films such as gate wiring, gate insulating film, semiconductor layer, data wiring, pixel electrode film, counter electrode film, and insulating protective film with a thickness of several tens to several hundreds of nanometers on a large glass substrate of × 800 mm class. Has a structure in which about 1 million micron-order thin film transistors distributed by photolithography are distributed, and has a technical feature that large-area manufacturing technology and microfabrication technology coexist. . With such manufacturing process features
In the manufacturing process of the TFT-LCD, when the Mo or Mo-W alloy film shown in the prior art is used for the wiring as a wiring material advantageous for lowering the resistance, the resistance can be kept low.
Since the etching rate of Mo and Mo-W at the time of dry etching of the gate insulating film and the insulating protective film made of the iN film is high, the resistance of the Mo and Mo-W wiring portions increases and disconnection failure occurs. This problem becomes conspicuous when the area of the TFT-LCD is increased due to the increase in the area thereof, and when the width of the wiring is reduced due to the progress of the fine processing due to the high definition.

An object of the present invention is to provide a liquid crystal display device in which a disconnection failure of a wiring is reduced.

[0005]

The above-mentioned objects are achieved by the following items.

A plurality of gate wirings, a plurality of data wirings formed so as to intersect the plurality of gate wirings, a thin film transistor formed near an intersection of the gate wirings with the data wirings, and a gate insulation covering the gate wirings A liquid crystal display device having a substrate having a layer, a protective layer, a counter substrate facing the substrate, and a liquid crystal layer sandwiched between the substrate and the counter substrate, wherein at least one of a gate wiring and a data wiring is provided. Is a single-layer film or a multi-layer film, and at least Cr, Ti
This is a configuration using a metal film to which is added.

The W composition of this metal film is 0.5-30 w
It is preferable to use a metal film in the range of t%.

The W composition of this metal film is 0.5-20 w
It is preferable to use a metal film having a Cr composition in the range of 5% to 15% by weight in the range of t%.

The W composition of the metal film is 0.5 -1.
It is preferable to use a metal film having a Ti composition in a range of 5 wt% and a Ti composition of 5 to 20 wt%.

[0010]

(Embodiment 1) Mo film, Mo-W
Film, Mo-W-Cr film and Mo-W-Ti film
This is an example in which a dry etching rate by F ₆ gas, a specific resistance, and a critical strength on a glass substrate were examined. The critical strength is an index of the adhesive strength of the film to the glass substrate, and the scratch test was evaluated. What is a scratch test?
A method in which a diamond needle vibrated in a direction parallel to the film surface is brought into contact with the film surface to increase the contact force between the film and the needle.If the contact force exceeds the adhesive force, film peeling occurs. By this method, the adhesion of the film to the substrate can be evaluated. FIGS. 1A, 1B, and 1C respectively show a Mo-W film, a Mo-W-Cr film, and a Mo-W-Ti film formed on a glass substrate.
The W composition dependency of the dry etching rate, specific resistance, and critical strength of the film. The Mo- (x) wt% W film is used, and the W composition x is plotted on the horizontal axis. Mo-W-Cr film, Mo-W-Ti
For the film, the horizontal axis represents the W composition x when the Cr composition was fixed at 0.5 wt% and 20 wt% and the Ti composition was fixed at 0.5 wt% and 15 wt%. Gate wiring and drain wiring are used for gate insulating films and insulating protective films.
Although placed below the iN film, when the SiN film is dry-etched using SF ₆ gas, if the gate wiring and the drain wiring are dry-etched, resistance increase and disconnection may occur. The dry etching rate of the SiN film is about 10
The dry etching rate of pure Mo is about 2 nm / sec, as shown in FIG. 1A, and pure Mo is etched during dry etching of the SiN film to increase the resistance. When W is added to Mo, the dry etching rate is reduced, but even when 30 wt% is added, about 0.9 is added.
It is not a sufficiently low value in nm / sec. On the other hand, Mo-WC
In the r film, the W composition is 0.5 to 30 wt% and the Cr composition is 0.5.
In the range of −20 wt%, the Mo—W—Ti film has a W composition of 0.5 to 30 wt%, a Ti composition of 0.5 to 15 wt%, a dry etching rate of 0.2 nm / sec, and a Si content.
It was greatly reduced to about 1/50 of the N film. The dry etching time of the SiN film is set to be 1.3 times as long as the etching time for the normal film thickness. The normal SiN film is 500 nm and the metal film is 200 nm. After dry etching, the resistance of the metal wiring is increased by about 15% in the case of the Mo film,
In the film, the increase is about 8%.
In the case of the r film and the Mo-W-Ti film, the resistance rise is 1% or less. Also, as shown in FIG. 1B, the specific resistance of the film is:
It gradually increases with the addition of W, Cr and Ti. Mo-
In the case of the W—Cr film, the W composition is in the range of 0.5-30 wt% and the Cr composition is in the range of 0.5-20 wt%.
W composition 0.5-30 wt%, Ti composition 0.5-15 wt%
, The specific resistance is 13 μΩcm or less. SXGA with a resolution of 18 inches or more (1024 vertical, 1280 horizontal)
In this case, about 13 μΩcm or less is required. FIG.
As shown in (c), the critical strength of the pure Mo film is as low as about 50 mN, whereas the Mo—W—Cr film has a W composition of 0.5 −
In a range of 30 wt% and a Cr composition of 0.5 to 20 wt%, M
In the o-W-Ti film, the W composition is 0.5-30 wt%,
When the composition is in the range of 0.5 to 15 wt%, it is more than doubled to 110 mN. In a pure Mo film, film peeling occurs in a processing step after the film is formed, but the Mo—W—Cr film and the Mo—W—
No film peeling occurs in the Ti film. As described above, Mo of 0.5 to 30 wt% of W composition and 0.5 to 20 wt% of Cr composition is obtained.
-W-Cr film or W composition at 0.5-30 wt%
By using a Mo—W—Ti film having an i composition of 0.5 to 15 wt%, the etching rate of SF _{6 with} respect to the pure Mo film is 1/10 or less, the glass adhesion is twice or more, and the specific resistance is 13 μΩcm. The following wiring is obtained. Also, FIG.
Al alloy (specific resistance 4-5μΩc
m) is a cross-sectional shape of the wiring laminated. The Al alloy is mainly composed of Al and at least Nd, Zr, L
An alloy film containing any of a, Y, and Sm can be used. Normally, in a laminated wiring, it is necessary to process each layer with a different etching solution.
The oW-Ti film can be processed with a mixed acid (phosphoric acid: nitric acid: acetic acid: pure water) which is an etching solution for the Al alloy film.
It has the feature that it can be processed in a single etching process. FIG.
FIG. 2A shows a processing example of a single-layer wiring 1 made of a Mo—W—Cr film and a Mo—W—Ti film having a thickness of 150 to 400 nm on a glass substrate 2, and FIG. Film thickness 20
Processing example in which an Al alloy film having a film thickness of 100 to 350 nm is disposed on the lower wiring 4 having a two-layer structure using either a Mo-W-Cr film or a Mo-W-Ti film having a thickness of 200 to 200 nm, FIG.
(C) shows a film thickness of 20 to 200 nm for the three-layer structure upper wiring 5.
Mo-W-Cr film or Mo-W-Ti film, an Al alloy film having a thickness of 100 to 350 nm for the three-layer structure intermediate wiring 6, and a M-layer having a thickness of 20 to 200 nm for the lower wiring for the three-layer structure.
This is a processing example when an o-W-Cr film or a Mo-W-Ti film is provided.

(Embodiment 2) Subsequently, Mo-25 wt% W
This is an example in which a −10 wt% Cr film is applied to a gate wiring and a drain wiring of a liquid crystal display device of a lateral electric field liquid crystal driving method.
Here, the lateral electric field liquid crystal driving method is a method in which a liquid crystal molecule is driven by applying an electric field in a horizontal direction to a glass substrate surface sandwiching the liquid crystal, and has a feature that a viewing angle can be widened. FIG.
A gate wiring 8, a counter electrode 9, a data wiring 10, a drain electrode 11, and a thin film transistor (TFT) 12 are shown as a planar pattern of a pixel of a liquid crystal display device and a peripheral portion thereof, which are components of the pixel. However, the counter electrode 9 is formed from the same thin film as the gate wiring 8 by photolithography, and the drain electrode 11 is formed from the same thin film as the data wiring 10 by photolithography. FIG. 4 is a sectional view taken along the line AA '. The display panel has a gate glass 14, a counter electrode lower layer 17, a counter electrode intermediate layer 18, a counter electrode upper layer 19, and a gate insulating film upper layer SiN on one surface of a TFT glass substrate 13.
A film 20, an intrinsic semiconductor 21, an N-type semiconductor 22, a data wiring 10, a drain electrode 11, a protective film 23, an alignment film 24, a color filter 26, a black matrix 27 on one surface of a counter glass substrate 25. , A counter substrate protection film 28 and a counter substrate alignment film 29 are formed.
It comprises a liquid crystal layer 30 sandwiched between the FT glass substrate 13 and the opposing glass substrate 25, a deflecting plate 31, and an opposing deflecting plate 32.

FIG. 5 is a flowchart of the manufacturing process. First, on the entire surface of one side of the TFT glass substrate 13, DC
Mo-25wt% W of 200nm thickness by sputtering
A -10 wt% Cr film 14 is formed by sputtering. The substrate temperature is 120 ° C. and the Ar pressure is 0.3 Pa. A photo process (applying a photoresist, performing selective pattern exposure using a mask, and performing pattern development: this operation is hereinafter referred to as a photo process) is performed on the alloy film, and then a PAN mixed acid (phosphoric acid: nitric acid: Acetic acid: pure water = 65: 9.6: 3.4: 2
(5.3 vol%, 40 ° C.) to etch the metal film to form a pattern of the gate wiring lower layer 14 and the counter electrode 19. Next, the SiN film 20 (having a thickness of 15
0 nm), intrinsic semiconductor 21 (amorphous Si, thickness 200 n)
m), N-type semiconductor 22 (amorphous Si, 35 nm thick) is continuously formed by CVD using a plasma CVD apparatus at a substrate temperature of 300 ° C. Here, a photo process is performed, and the intrinsic semiconductor 21 and the N-type semiconductor 22 are patterned by etching (using SF ₆ gas). Subsequently, a 200 nm thick M
An o-25 wt% W-10 wt% Cr film is formed by DC sputtering (substrate temperature: 130 ° C., Ar pressure: 0.3 P). Here, a photo process is performed, and then a PAN mixed acid (phosphoric acid: nitric acid: acetic acid: pure water = 65: 9.6: 3.4: 2).
(5.3 vol%, 40 ° C.) to etch the metal film to form the data wiring 10 and the drain electrode 11. Further, an SiN protective film 23 (thickness: 500 nm) is formed by CVD using a plasma CVD apparatus. Thereafter, the SiN protective film 23 is further processed by photolithography and dry etching using SF ₆ gas for taking out the terminal portion.

FIG. 6 is a plan view schematically showing a peripheral portion of the display panel. When a display panel is manufactured, liquid crystal is sealed through an opening 35 of a seal pattern 34 in which the TFT glass substrate 13 and the opposing glass substrate 25 are bonded. A gate terminal group 37 and a data terminal group 38 are arranged on the screen section 36 as shown in the figure. A plurality of gate lines 8 (scanning signal lines or horizontal signal lines) parallel to each other and data lines 10 (video signal lines or vertical signal lines) parallel to each other are formed on the TFT glass substrate 13. Are formed. A region surrounded by two adjacent gate lines 8 and two adjacent data lines 10 is a pixel region. As in the present embodiment, by using a Mo-25 wt% W-10 wt% Cr film for the gate wiring and the drain wiring, the gate wiring and the drain wiring at the time of dry etching of the gate insulating film made of the SiN film and the insulating protective film are used. Etching can be prevented, and wiring disconnection defects and the like can be reduced.

Example 3 Subsequently, Mo-25 wt% W
This is an example in which a −10 wt% Cr film is applied to a gate wiring and a drain wiring of a vertical electric field driving type liquid crystal display device. FIG.
Is a planar pattern of one pixel of the manufactured liquid crystal display device and its peripheral portion. Gate wiring 8, data wiring 10, light shielding film 39, transparent pixel electrode 40,
The TFT 12 is shown. FIG. 8 is a sectional view taken along the line AA '. The display panel has a gate wiring lower layer 14, a gate wiring intermediate layer 15, a gate wiring upper layer 16, an SiN film 20 as a gate insulating film, an intrinsic semiconductor 21, an N-type semiconductor 22, a data wiring 10, a protection layer on one surface of a TFT glass substrate 13. One in which a film 23, a transparent pixel electrode 40, and an alignment film 24 are formed, and another in which a color filter 26, a counter substrate protection film 28, a transparent pixel electrode 40, and a counter substrate alignment film 29 are formed on one surface of a counter glass substrate 25. And the TFT glass substrate 13
, A liquid crystal layer 30 sandwiched between opposed glass substrates 25, a deflecting plate 31, and an opposed deflecting plate 32.

FIG. 9 is a flowchart of the manufacturing process. First, on the entire surface of one side of the TFT glass substrate 13, DC
By sputtering method, Mo-25wt% W-
A 10 wt% Cr film 14 is formed by sputtering. The substrate temperature is 130 ° C. and the Ar pressure is 0.3 Pa. A photo-process (coating a photoresist, performing selective pattern exposure using a mask, and performing pattern development: this operation is hereinafter referred to as a photo-process) is performed on the alloy film, and then a mixed acid (phosphoric acid: nitric acid: acetic acid) : Pure water = 65: 9.6: 3.4: 25.3vol%,
At 40 ° C.), the metal film is etched to form patterns of the gate wiring 8 and the light shielding film 39. Next, TFT
An SiN film 20 (150 nm thick), an intrinsic semiconductor 21 (amorphous Si, 200 nm thick), an N-type semiconductor 2
2 (amorphous Si, thickness 35 nm) is formed by CVD using a plasma CVD apparatus at a substrate temperature of 300 ° C. Here, a photo process is performed, and the intrinsic semiconductor 21 and the N-type semiconductor 22 are formed.
Is patterned by etching (using SF ₆ gas). Subsequently, a 200 nm thick Mo-25 wt% W-10 wt
A% Cr film is formed by sputtering at a substrate temperature of 130 ° C. by a DC sputtering method. A photo process is performed, and then a mixed acid (phosphoric acid: nitric acid: acetic acid: pure water = 65: 9.6: 3.4: 25.
(3 vol%, 40 ° C.), the metal film is etched to form the data wiring 10, and the N-type semiconductor 22 is patterned by dry etching (using SF ₆ gas) using the data wiring pattern as a mask. Furthermore, plasma CVD
The SiN protective film 23 (thickness 500 nm) is
A VD film is formed. The protection film 23 is dry-etched (using SF ₆ gas) by a photo process to form a through hole exposing the data wiring 10 on the spot. Here, [In ₂ O ₃ -SnO ₂ (10 wt.
%)], A tin-added indium oxide (ITO) transparent pixel electrode 40 is formed by sputtering using a DC sputtering apparatus. The substrate temperature was 215 ° C., and the sputtering gas was Ar
And a mixed gas of O ₂ was used. A photolithography process is performed, and the transparent pixel electrode 33 is etched at 30 ° C. using HBr to form a predetermined pattern. Thus, a TFT substrate of the liquid crystal display device is manufactured.

FIG. 3 is a plan view schematically showing a peripheral portion of the display panel. When a display panel is manufactured, liquid crystal is sealed through an opening 35 of a seal pattern 34 in which the TFT glass substrate 13 and the opposing glass substrate 25 are bonded. A gate terminal group 37 and a drain terminal group 38 are arranged on the screen unit 36 as shown in the figure. A plurality of gate lines 8 (scanning signal lines or horizontal signal lines) parallel to each other and parallel data lines 10 (video signal lines or vertical signal lines) formed crossing the gate lines 8 are formed on the TFT substrate 13. Is formed. A region surrounded by two adjacent gate lines 8 and two adjacent data lines 10 is a pixel region,
A transparent pixel electrode 40 is formed on almost the entire surface. As in the present embodiment, Mo-25w is applied to the gate wiring and the drain wiring.
By using the t% W-10 wt% Cr film, it is possible to prevent the gate wiring and the drain wiring from being etched during the dry etching of the gate insulating film and the insulating protective film made of the SiN film, and to prevent the disconnection of the wiring from occurring. Reduction is possible.

The Mo—W—Cr film or Mo—W— film of the present invention
By using the Ti film for at least one of the gate wiring and the drain wiring, it is possible to prevent dry etching of at least one of the gate wiring and the drain wiring during dry etching of the gate insulating film and the insulating protective film made of the SiN film. In addition, it is possible to reduce the disconnection failure of the wiring and the like, and to provide an inexpensive liquid crystal display device.

[0018]

According to the present invention, it is possible to provide a liquid crystal display device in which the disconnection failure of the wiring is reduced.

[Brief description of the drawings]

FIG. 1 shows the dependence of dry etching rate, specific resistance and critical strength on film composition.

FIG. 2 is a cross-sectional structure of a wiring.

FIG. 3 is a plan view of a pixel and its peripheral portion.

FIG. 4 is a sectional view taken along line AA ′ of FIG. 2;

FIG. 5 is a manufacturing flowchart of a liquid crystal display device driven by a lateral electric field.

FIG. 6 is a schematic plan view of a liquid crystal display device.

FIG. 7 is a plan view of a pixel of a vertical electric field driving liquid crystal display device and its peripheral portion.

FIG. 8 is a sectional view taken along line AA ′ of FIG. 6;

FIG. 9 is a manufacturing flowchart of a vertical electric field driving liquid crystal display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Single layer wiring, 2 ... Glass substrate, 3 ... Double layer structure upper layer wiring, 4 ... Double layer structure lower layer wiring, 5 ... Triple layer structure upper layer wiring film,
6 ... three-layer structure middle layer wiring, 7 ... three-layer structure lower layer wiring, 8,
14 gate wiring, 9, 17 counter electrode, 10 data wiring, 11 drain electrode, 12 thin film transistor (TFT), 13 TFT glass substrate, 20 SiN
Film, 21: intrinsic semiconductor, 22: N-type semiconductor, 23: protective film, 24: alignment film, 25: counter glass substrate, 26: color filter, 27: black matrix, 28: counter substrate protective film, 29: counter substrate Alignment film, 30 ... liquid crystal layer, 31
... Deflecting plate, 32… opposed deflecting plate, 34… seal pattern,
35 ... opening, 36 ... screen, 37 ... gate terminal group, 3
8 Data terminal group, 39 light shielding film, 40 transparent pixel electrode, 41 common transparent electrode.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Kenichi Onizawa 7-1-1, Omikacho, Hitachi City, Ibaraki Prefecture Inside the Hitachi Research Laboratory, Hitachi, Ltd. No. 1 Inside Hitachi, Ltd.Hitachi Research Laboratories (72) Inventor Toshiki Kaneko 3300 Hayano, Mobara-shi, Chiba Prefecture Inside Display Group, Hitachi, Ltd. (72) Inventor Masanori Terado 3300 Hayano, Mobara-shi, Chiba Hitachi, Ltd. F-term in the display group of the factory (reference) 2H092 GA14 HA28 JA24 JA33 JB24 JB33 KA05 KA12 KB05 MA05 MA07 MA18 NA15 NA29 PA08 PA09 5C094 AA42 AA43 AA44 BA03 BA43 CA19 DA13 EA03 EA04 EA07 FB02 FB12 JA01

Claims (9)

[Claims] A plurality of gate lines, a plurality of data lines formed so as to intersect the plurality of gate lines, a thin film transistor formed near an intersection of the gate lines and the data lines, and the gate line. A substrate having a gate insulating layer covering the substrate, a protective layer, a counter substrate facing the substrate, and a liquid crystal layer sandwiched between the substrate and the counter substrate; At least one of the wiring and the data wiring is a single-layer film or a multilayer film, and has a metal film in which at least one selected from Cr and Ti is added to an alloy mainly composed of Mo and W as a constituent layer thereof. Characteristic liquid crystal display device. 2. The liquid crystal display device according to claim 1, wherein the W composition of said W is in the range of 0.5-30 wt%. 3. The Cr composition of the Cr is 0.5-20 wt.
%. 4. The method according to claim 1, wherein said Ti has a Ti composition of 0.5-15 wt.
%. 5. The liquid crystal display device according to claim 1, wherein said multilayer film is a two-layer film, and has at least Al or an alloy film mainly composed of Al as a constituent layer thereof. 6. The liquid crystal display device according to claim 1, wherein said multilayer film is a three-layer film, and has at least Al or an alloy film mainly composed of Al as a constituent layer thereof. 7. The liquid crystal display device according to claim 5, wherein the alloy film mainly composed of Al is mainly composed of Al and contains at least one of Nd, Zr, La, Y, and Sm. A liquid crystal display device comprising an alloy film. 8. The liquid crystal display device according to claim 1, further comprising: a drain electrode connected to the transistor; and a counter electrode disposed opposite to the drain electrode, wherein the gate wiring is connected to the drain electrode. A metal in which at least one selected from Cr and Ti is added to an alloy mainly composed of Mo and W as a constituent layer of a single-layer film or a multilayer film in at least one of the data, the drain electrode, and the counter electrode. A liquid crystal display device comprising a film. 9. The liquid crystal display device according to claim 1, further comprising a drain electrode connected to said transistor, wherein at least one of said gate line, said data, said drain electrode and said counter electrode is provided. Finally, a liquid crystal display device comprising a metal film which is a single-layer film or a multi-layer film and whose constituent layer is an alloy mainly composed of Mo and W and at least one of Cr and Ti added thereto.