JP4747139B2 - Manufacturing method of liquid crystal display device - Google Patents

Description

The present invention relates to a method of manufacturing a liquid crystal display device, and more specifically, in a process of manufacturing wiring and electrodes using aluminum (Al) or an aluminum alloy (Al alloy).
And the technology for improving the corrosion resistance of Al alloys.

In a liquid crystal display device using a thin film transistor (TFT) as a switching element, problems such as writing and crosstalk occur when a wiring delay occurs in a scanning line or a signal line. In particular, in a large-sized high-definition liquid crystal display device, low-resistance wiring is used for scanning lines and signal lines in order to avoid this problem. As the low resistance wiring, Al or an Al alloy is widely used. However, in order to ensure ohmic contact with a semiconductor layer or a transparent conductive film, a refractory metal is usually laminated, for example, a refractory metal (upper layer) / Al ( (Lower layer) two-layer wiring and refractory metal / Al / refractory metal three-layer wiring are used.

Further, when the process is shortened in order to reduce the manufacturing cost, it is required to form these laminated wirings by one photo process. In this case, the side surface of the Al (alloy) film is directly exposed on the surface.

Inverted stagger type T using three-layer laminated wiring of refractory metal / Al (alloy) / refractory metal for the signal line
In FT, channel etching and semiconductor layer etching are usually performed by dry etching using a fluorine-based gas such as SF ₆ or CHF _3, a chlorine-based gas such as Cl ₂ or HCl, or a mixed gas thereof. However, since the side surface of the Al (alloy) film is directly exposed, there is a problem that Al is corroded by the influence of the dry etching gas. This phenomenon is caused by the reaction of the fluorine-based gas or chlorine-based gas with the Al (alloy) film to form Al fluoride or Al chloride, or when the substrate on which the fluorine-based gas or chlorine-based gas remains is taken out into the atmosphere. It is considered that hydrofluoric acid and hydrochloric acid are generated by the reaction with moisture in the atmosphere, and the Al (alloy) film is eroded by these.
Therefore, a method for manufacturing a liquid crystal display device that prevents such Al corrosion has been demanded.

Conventionally, as a method for preventing local battery corrosion due to a combination of different metal materials, for example, Patent Document 1 discloses a liquid crystal display device in which a source, a drain electrode, and a signal line are formed of a refractory metal, Al, or a refractory metal. In the manufacturing method, a technique for preventing local battery corrosion between Al and a refractory metal generated in a resist stripping process or the like by forming an oxide film on the interface and side surfaces of Al and the refractory metal is disclosed. In this case, the oxide film on the Al side surface is plasma oxidized or anodized,
It is described that it is formed by various CVD and PVD.
JP-A-8-62628 (5th page, FIGS. 1, 3 and 4) JP-A 63-276242 (table on pages 7 and 8)

In the above-mentioned Patent Document 1, plasma oxidation, anodic oxidation, various CVD, PVD are applied to the side surface of Al.
However, in any case, the number of manufacturing steps increases. further,
In plasma oxidation, it is difficult to obtain an oxide film having a sufficient thickness in a short time. The thin oxide film of about several nanometers described in the embodiment cannot prevent the etching gas from entering during the dry etching in the subsequent process, and cannot prevent the corrosion of Al. Anodization can provide an oxide film having a sufficient thickness. However, in order to anodize the side surfaces of the source and drain electrodes and the signal line, it is necessary to select a refractory metal that can be anodized. Mo described in the examples cannot be anodized (for example, see Patent Document 2). In addition, in CVD and PVD, it is considered that at least an etching back process is required in addition to the film forming process, and the manufacturing process becomes complicated.

An object of the present invention is to provide a corrosion resistance of Al or Al alloy without complicating the process in patterning a laminated metal film of a semiconductor layer and a refractory metal film and a low resistance metal film made of Al or Al alloy. An object of the present invention is to provide a method of manufacturing a liquid crystal display device with improved properties.

The method for producing a liquid crystal display device according to the present invention is a method for producing a liquid crystal display device in which a semiconductor layer and a laminated metal film of a refractory metal film and a low resistance metal film are patterned on a substrate. Forming a photoresist pattern on the substrate, etching the stacked metal film using the photoresist as a mask to form the stacked metal film pattern, and forming the stacked metal film pattern using the photoresist or the stacked metal film as a mask. A step of performing a dry etching on a part or all of the substrate, and a step of evacuating a chamber containing the substrate after the dry etching, and a step of performing a plasma treatment on the substrate after the evacuation step. An etching gas remaining on the substrate by the vacuuming step and the plasma processing step. And removing the.

  In a preferred aspect of the method for manufacturing a liquid crystal display device of the present invention, the evacuation is performed in a state where the substrate is separated from the electrode of the chamber. The evacuation is more preferably performed for 120 seconds or more.

In the method for manufacturing a liquid crystal display device of the present invention, it is also a preferable aspect that the plasma treatment is performed with any gas of O ₂ , N ₂ , H ₂ , and He.

According to the method for manufacturing a liquid crystal display device of the present invention, chlorine-based gas and fluorine-based gas adhering to a substrate during etching of a semiconductor layer or channel etching can be efficiently removed, and corrosion of an Al (alloy) film can be suppressed. .

Hereinafter, the manufacturing method of the liquid crystal display device of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a conceptual diagram showing the configuration of a thin film transistor array substrate (TFT substrate) used in the liquid crystal display device of the present invention.

As shown in FIG. 1, on the TFT substrate 10, a plurality of scanning lines 11 and a plurality of signal lines 12 are arranged substantially orthogonally on a transparent insulating substrate, and switching is connected in the vicinity of the intersection. Element thin film transistors (TFTs) 13 are provided and arranged in a matrix. A scanning line terminal 14 for inputting an address signal is provided at the end of the scanning line 11, and a signal line terminal 15 for inputting a data signal is provided at the end of the signal line 12.

  Next, the configuration of the first embodiment of the liquid crystal display device of the present invention will be described.

FIG. 2 shows a TFT substrate 1 used in the first embodiment of the method for manufacturing a liquid crystal display device of the present invention.
FIG. 3 is a plan view of a pixel portion, and FIGS. 3 to 5 are sectional views of manufacturing steps in order of manufacturing steps of a TFT substrate used in the method of manufacturing a liquid crystal display device of the present invention. Here, the sectional view of the manufacturing process includes a TFT portion, a pixel portion (A-A line in FIG. 2), a signal line terminal portion (BB line in FIG. 1), and a scanning line terminal portion (CC line in FIG. 1). ) When cut along line. The first embodiment is an example of a liquid crystal display device having an inverted stagger channel etch type TFT substrate manufactured using five masks.

The TFT substrate shown in FIGS. 2 and 4B includes a gate electrode 21, a scanning line 11 connected to the gate electrode 21, and a storage capacitor electrode 31 sharing the preceding scanning line on a transparent insulating substrate 20. The light shielding layer 32 and the terminal part metal film 33 of the scanning line terminal 14 are formed, and the gate electrode 2 is formed.
1 is provided with a gate insulating film 22, a semiconductor layer 23 is provided on the gate insulating film 22 so as to face the gate electrode 21, and a source electrode 24 and a drain electrode 25 are separately formed on the semiconductor layer 23. ing. Further, the source electrode 24, the drain electrode 25, and the gate insulating film 2
A passivation film 26 is provided on the signal line 12 connected to the drain electrode 25 provided on 2 and the terminal portion metal film 34 of the signal line terminal 15, and the passivation film 26 is provided.
A pixel portion contact hole 35 and a terminal portion contact hole 36 are provided in a part of the pixel portion.
A pixel electrode 27 connected to the source electrode 24 and a connection electrode 37 connected to the terminal portion metal films 33 and 34 are provided through the contact holes 35 and 36. Here, a storage capacitor is formed between the storage capacitor electrode 31 and the pixel electrode 27.

4B, in the TFT substrate used in the liquid crystal display device of the present invention, the source electrode 24 and the drain electrode 25, the signal line 12, and the terminal part metal film 3 of the signal line terminal.
4 has a laminated structure in which an Al (alloy) layer is sandwiched between refractory metal layers from above and below, and a protective film 38 is formed on the side surface of the Al (alloy) layer.

Next, a manufacturing method of the first embodiment of the liquid crystal display device of the present invention will be described. The manufacturing method of the TFT substrate used in the liquid crystal display device according to the first embodiment of the present invention includes (a) a step of forming a gate electrode and a scanning line on a transparent insulating substrate, (b) a gate insulating film and a semiconductor layer. (C) a step of forming a source / drain electrode and a signal line, (d) a step of forming a passivation film and a contact hole, and (e) a step of forming a pixel electrode. In the step (c), the source, drain electrodes and signal lines are formed in a three-layer structure in which an Al (alloy) layer is sandwiched from above and below by a refractory metal layer, and a protective film is formed on the side surface of the Al (alloy) layer. It is characterized in that it is formed and evacuated in the same vacuum after dry etching at the time of channel formation.

As shown in FIGS. 3 to 5, first, an Al or Al alloy layer having a thickness of about 200 nm and a thickness of about 10 are formed on a transparent insulating substrate 20 made of non-alkali glass having a thickness of 0.7 mm by sputtering.
A refractory metal layer having a thickness of 0 nm is formed, and the gate electrode 21, the scanning line (not shown), the storage capacitor electrode (not shown), the light shielding layer (not shown), and the scanning line terminal are formed by photolithography and etching. A terminal portion metal film 33 is formed (FIG. 3A). Here, as the Al alloy, aluminum-silicon (Al-Si), aluminum-copper (Al-Cu), aluminum-neodymium (Al-Nd) alloy and the like are used, and as the refractory metal, chromium (Cr), tantalum (Ta) ), Niobium (Nb), titanium (Ti), hafnium (Hf), zirconium (Zr), molybdenum (Mo), tungsten (W), and alloys thereof, or nitrides thereof are selected. Is done. Etching may be performed by wet etching or dry etching according to the types of Al (alloy) and the refractory metal, or may be performed in combination with wet etching and dry etching.

Next, a gate insulating film 22 made of a silicon nitride film having a thickness of about 400 nm, an amorphous silicon (a-Si type) layer 28 having a thickness of about 200 nm, and a thickness of about 30 nm are formed by plasma CVD.
An N-type amorphous silicon (n + -type a-Si) layer 29 doped with phosphorus is sequentially formed, and a semiconductor layer 23 is formed by photolithography and etching (FIG. 3B).

Next, a high melting point metal layer having a thickness of about 50 nm and Al or A having a thickness of 200 nm are formed by sputtering.
An l alloy layer and a refractory metal layer having a thickness of about 100 nm are sequentially formed, and a source electrode 24, a drain electrode 25, a signal line 12, and a terminal part metal film 34 of a signal line terminal are formed by photolithography and etching. For this etching, dry etching may be used, but it is preferable to perform wet etching because of the need to prevent corrosion of the Al (alloy) film. Therefore, an Al alloy material or a refractory metal material is selective with respect to the transparent insulating substrate or the gate insulating film, and a material that can be etched with an etching solution that does not generate a residue is selected. For example, in the case of Cr (alloy), it can be etched with second ceric ammonium nitrate and nitric acid, in the case of Mo (alloy), phosphoric acid, nitric acid and acetic acid, and in the case of W (alloy), it can be etched with hydrogen peroxide. In particular, M
o (alloy) is advantageous because it can be etched with the same etchant as Al (alloy).

Here, as a first major feature of the present embodiment, the signal line metal film is side-etched by about 0.5 to 1 μm from the end portion of the photoresist as a mask by wet etching. Furthermore, as the second major feature, washing with water after etching is performed with hot water of 40 ° C. to 50 ° C.,
A protective film 38 made of an Al (alloy) oxide film or a hydroxide film is formed on the side wall of the Al (alloy) film. The lateral thickness of the protective film 38 varies depending on the temperature of the hot water, but is 200 to 300 nm.
Degree.

Next, the n + -type a-Si layer 29 between the source electrode 24 and the drain electrode 25 is removed by etching, and then the photoresist is removed (FIG. 3C). This etching may be performed by, for example, etching with a mixed gas of sulfur hexafluoride (SF ₆ ), chlorine (HCl), and helium (He), or trifluoride methane (CHF ₃ ), oxygen (O ₂ ), and helium (He). Mixed gas of SF ₆ and HCl and He, or mixed gas of CHF ₃ , O ₂ and He and SF ₆ and C
Two-step etching using a mixed gas of HF ₃ and He or the like is performed using a fluorine-based gas or a fluorine-based gas and a chlorine-based gas. Etching may be performed by either plasma etching (PE mode) or reactive ion etching (RIE mode). In etching using any of these gases, A
Since the protective film 38 is formed on the side wall of the l (alloy) film, the Al (alloy) film is not directly exposed to the etching gas plasma. Further, since the signal line metal film is shaded by retreating from the end portion of the photoresist, the chance that the side wall of the Al (alloy) film is exposed to the etching gas plasma can be greatly reduced.

Subsequently, after the dry etching, evacuation is performed in the same chamber. The evacuation varies depending on the chamber volume and the pump capacity, but the chamber volume: 120 liters,
Pumping capacity: When the pressure is around 25 Pa and 100 Pa · l (liter) / second, it is performed for 120 seconds or more.
Desirably, 240 seconds or more are desirable under the same conditions. Further, in order to remove the etching gas adhering to the back surface of the substrate, the substrate is separated from the electrode and evacuation is performed.

Further, after the evacuation process, oxygen (O ₂ ), nitrogen (N ₂ ), hydrogen (
Plasma treatment is performed with either H ₂ ) or helium (He) gas. By performing this plasma treatment, residual fluorine and residual chlorine components that could not be completely removed by evacuation can be replaced.

When the residual fluorine and residual chlorine components are not removed and transported to the atmosphere as they are, F or Cl adhering to the substrate reacts with moisture in the atmosphere to become HF or HCl, which corrodes the Al (alloy) film. By using the above method, the Al (alloy) film is not exposed to the etching gas plasma, and F and Cl adhering to the substrate can be removed, thereby preventing Al corrosion. (Described later).

Further, the vacuuming process and the plasma treatment after the dry etching are continuously performed in the same vacuum after the dry etching. Separately, by performing washing treatment such as water washing and wet peeling after opening to the atmosphere, Fluorine and residual chlorine components can also be removed (in the above-described embodiment, a photoresist stripping removal process is applicable). In this case, it is necessary to perform a cleaning process promptly before F or Cl adhering to the substrate when released to the atmosphere reacts with moisture in the atmosphere to become HF or HCl.
Therefore, this cleaning process is preferably a batch method in which a plurality of substrates can be processed at the same time, and the back surface of the substrate can be cleaned, and is preferably performed within 10 minutes after release to the atmosphere after dry etching. (Described later).

Here, an example in which the protective film is formed by washing with warm water at the time of washing with water after wet etching of the signal line metal film has been described. However, washing with warm water may be similarly performed at the time of washing with water after peeling off the photoresist. In this case, the above-described dry etching for forming the channel is performed using the metal films of the source and drain electrodes as a mask.

Next, a passivation film 26 made of a silicon nitride film having a thickness of about 200 nm is formed by plasma CVD, and a pixel portion contact hole 35 and a terminal portion contact hole 36 are opened by photolithography and etching (FIG. 4A). ).

Next, a transparent conductive film made of an indium tin oxide film (ITO) or an indium zinc oxide film (IZO) having a thickness of about 50 nm is formed by sputtering, and the pixel electrode 27 and the connection electrode of the terminal portion are formed by photolithography and etching. 37 is formed and annealed at a temperature of about 270 ° C. to complete the TFT substrate. (FIG. 4B).

Next, an alignment film 41 having a thickness of about 50 nm is formed on the TFT substrate 10 by printing,
Baking is performed at a temperature of about 220 ° C., and alignment treatment is performed.

On the other hand, a counter substrate 40 is formed facing the TFT substrate 10. The counter substrate 40 has a thickness of 0
. A transparent insulating substrate 50 made of 7 mm alkali-free glass, a color filter 42 provided on the transparent insulating substrate 50 and corresponding to each pixel region of the TFT substrate 10, and a black matrix corresponding to the peripheral portion of the pixel region including the TFT portion 43, and a common electrode 44 made of a transparent conductive film such as ITO covering them. An alignment film 41 having a thickness of 50 nm is formed by printing on the uppermost layer of the TFT substrate 10 and the counter substrate 40, and is baked at a temperature of about 220 ° C. to perform an alignment process. The TFT substrate 10 and the counter substrate 40 are spaced apart from each other by a seal 45 made of an epoxy resin adhesive and an in-plane spacer (not shown) made of plastic particles or the like so that the film surfaces face each other. To overlay. Thereafter, liquid crystal 46 is injected between the TFT substrate 10 and the counter substrate 40, and a space (not shown) of the seal 45 into which the liquid crystal 46 is injected is sealed with a sealing material (not shown) made of a UV curable acrylate resin. ). Finally, a deflection plate 47 is pasted on the surface opposite to the film surface of the TFT substrate 10 and the counter substrate 40 to complete the liquid crystal display panel (FIG. 5).

Thereafter, although not shown, a tape carrier package (TCP) connected to the drive circuit is pressed onto the scanning line terminals 14 and the signal line terminals 15 to complete the liquid crystal display device.

  Next, the configuration of the second embodiment of the liquid crystal display device of the present invention will be described.

FIG. 6 is a plan view of one pixel portion of a TFT substrate used in the second embodiment, and FIGS. 7 to 10 are sectional views of manufacturing steps in order of manufacturing steps of the TFT substrate used in this embodiment. is there. Here, the sectional view of the manufacturing process includes a TFT portion and a pixel portion (A-A line in FIG. 6), a signal line terminal portion (BB line in FIG. 1), and a scanning line terminal portion (CC line in FIG. 1). It is sectional drawing when cut | disconnecting along line. The second embodiment is an example of a liquid crystal display device having an inverted stagger channel etch TFT substrate manufactured using four masks.

The TFT substrate shown in FIGS. 6 and 8B includes a gate electrode 21 on the transparent insulating substrate 20, a scanning line 11 connected to the gate electrode 21, and a storage capacitor electrode 31 sharing the preceding scanning line. And the light shielding layer 32 and the terminal metal film 33 of the scanning line terminal 14. A gate insulating film 22 is provided on the gate electrode 21, a semiconductor layer 23 is provided on the gate insulating film 22 so as to face the gate electrode 21, and a source electrode 24 and a drain electrode 25 are separated on the semiconductor layer 23. Has been formed.

Here, the difference from the first embodiment is that the source electrode 24 and the drain electrode 25 are formed on the semiconductor layer 23, and the end faces thereof are coincident with each other. A passivation film 26 is formed on the source electrode 24, the drain electrode 25, the signal line 12 connected to the drain electrode 25 provided on the gate insulating film 22, and the terminal metal film 34 of the signal line terminal 15. The pixel portion contact hole 35 and the terminal portion contact hole 36 are provided in a part of the passivation film 26. A pixel electrode 27 connected to the source electrode 24 and a connection electrode 37 connected to the terminal portion metal films 33 and 34 are provided through the contact holes 35 and 36. In addition, a storage capacitor is formed between the storage capacitor electrode 31 and the pixel electrode 27.

Further, as shown in FIG. 8B, T used in the method for manufacturing the liquid crystal display device of the present embodiment.
In the FT substrate, the source electrode 24, the drain electrode 25, the signal line 12, and the terminal part metal film 34 of the signal line terminal are laminated by laminating a refractory metal layer, an Al (alloy) layer, and a refractory metal layer from the lower layer. The protective film 38 is formed on the side surface of the Al (alloy) layer.

  Next, a second embodiment of the method for manufacturing a liquid crystal display device of the present invention will be described.

The manufacturing method of the TFT substrate used in the second embodiment includes (a) a step of forming a gate electrode and a scanning line on a transparent insulating substrate, (b) a gate insulating film, a source, a drain electrode, a signal line, and a semiconductor. A step of forming a layer, (c) a step of forming a passivation film and a contact hole, and (d) a step of forming a pixel electrode. Here, in the step (b), the source, drain electrodes and signal lines are formed in a three-layer structure of a refractory metal layer, an Al (alloy) layer and a refractory metal layer, and are protected on the side surfaces of the Al (alloy) layer. It is characterized by forming a film and evacuating in the same vacuum after dry etching at the time of forming a semiconductor layer and a channel.

First, an Al (alloy) layer having a thickness of about 200 nm and a refractory metal layer having a thickness of about 100 nm are formed on the transparent insulating substrate 20 made of alkali-free glass having a thickness of 0.7 mm by sputtering,
A gate electrode 21, a scanning line (not shown), a storage capacitor electrode (not shown), a light shielding layer (not shown), and a terminal layer metal film 33 of the scanning line terminal are formed by photolithography and etching (FIG. 7 (a)). Here, the types of Al (alloy) and the refractory metal and the etching method are the same as those in the first embodiment.

Next, an N-type amorphous silicon doped with a gate insulating film 22 made of a silicon nitride film having a thickness of about 400 nm, an amorphous silicon (a-Si) layer 28 having a thickness of about 200 nm, and phosphorus having a thickness of about 30 nm by plasma CVD. n + type a-Si) layer 29 is sequentially formed,
Further, a high melting point metal layer having a thickness of about 50 nm and Al (alloy) having a thickness of 200 nm are formed by sputtering.
A layer and a refractory metal layer having a thickness of about 100 nm are sequentially formed, and by photolithography and etching, the source electrode 24, the drain electrode 25, the signal line 12, and the terminal portion metal film 3 of the signal line terminal
4 and the semiconductor layer 23 are formed together (FIG. 7B).

In this embodiment, unlike the first embodiment, the source and drain electrodes and the semiconductor layer are formed in one step. This method will be described with reference to FIGS. 9 and 10 are cross-sectional views for explaining the process of FIG.

Three layers of a refractory metal layer 1, an Al (alloy) layer 2, and a refractory metal layer 3 laminated on a three-layer film composed of a gate insulating film 22, an a-Si layer 28 and an n + -type a-Si layer 29. A photoresist is applied on the film 4, exposure and development are performed, and the photoresist 51 is patterned into a staircase pattern with a predetermined pattern. At this time, exposure uses a halftone mask or a gray tone mask,
The photoresist 51 is formed thick only on the region facing the channel region at the portion that becomes the source and drain electrodes, and becomes the metal film of the terminal portion of the other regions, signal lines and signal line terminals at the portions that become the source and drain electrodes. A thin film is formed on the portion (FIG. 9A).

Next, the refractory metal layer 3, the Al (alloy) layer 2, and the three-layer film 4 of the refractory metal layer 1 are etched using the photoresist 51 as a mask (FIG. 9B). As in the first embodiment, the etching method is wet etching, and side etching is performed from the end face of the photoresist 51. Further, washing with water after etching is performed with warm water of 40 ° C. to 50 ° C., and a protective film 38 made of an Al (alloy) oxide film or a hydroxide film is formed on the side wall of the Al (alloy) film 2.

Next, O ₂ plasma treatment is performed, and the photoresist 52 is entirely ashed to remove the thin portion (FIG. 10A).

Next, after reflowing the photoresist 53 remaining with the vapor of the organic solvent such as N-methyl-2-pyrrolidone (NMP), the photoresist 53 and the terminal metal film of the source, drain electrode, signal line and signal line terminal are formed. Using the mask, the n + -type a-Si layer 29 and the a-Si layer 28 are etched (FIG. 10B). Etching methods include, for example, etching with a mixed gas of SF ₆ , HCl and He, a mixed gas of CHF ₃ , O ₂ and He and a mixed gas of SF ₆ , HCl and He, or CHF ₃ , O ₂ and He. Two-step etching with a mixed gas and a mixed gas of SF ₆ , CHF _3, and He is performed with a fluorine-based gas or a fluorine-based gas and a chlorine-based gas, but it is more preferable to perform with only a fluorine-based gas. This etching is performed by RIE. Further, after etching, similarly to the etching of the n + -type a-Si layer of the channel portion of the first embodiment, evacuation is performed in a state where the substrate is separated from the electrode in the same vacuum, and O ₂ ,
Plasma processing is performed with any of N ₂ , H ₂ , and He.

Subsequently, as in the first embodiment, the photoresist 53 is quickly removed by wet peeling, and then the n + -type a-Si between the electrodes is formed using the source electrode 24 and the drain electrode 25 as a mask.
Layer 29 is etched away. In this way, the source electrode 24, the drain electrode 25, the signal line 12, the terminal portion metal film 34 of the signal line terminal, and the semiconductor layer 23 are formed (FIG. 10C).
). The method for etching the n + -type a-Si layer in the channel portion, evacuation after etching, and plasma treatment are the same as in the first embodiment. In addition, after the etching of the n + -type a-Si layer, a water washing process is promptly performed in the same manner as the wet peeling process in the first embodiment. By using the method as described above, the Al (alloy) film is not exposed to the plasma of the etching gas, and F and Cl attached to the substrate can be removed, so that corrosion of Al can be prevented. it can.

Here, although an example of performing dry etching for channel formation using the metal films of the source and drain electrodes as a mask is shown, after the signal line metal film is wet-etched and washed with warm water, the process shown in FIG. Etching for channel formation may be performed using the photoresist as a mask in the state. In this case, the process after FIG. 10A is continued thereafter (however, in FIGS. 10A and 10B, the channel is already formed).

Next, a passivation film 26 made of a silicon nitride film having a thickness of about 200 nm is formed by plasma CVD, and a pixel part contact hole 35 and a terminal part contact hole 36 are opened by photolithography and etching (FIG. 8A). ).

Next, a transparent conductive film made of ITO or IZO having a thickness of about 50 nm is formed by sputtering, and the pixel electrode 27 and the terminal connection electrode 37 are formed by photolithography and etching.
And annealed at a temperature of about 270 ° C. to complete the TFT substrate (FIG. 8B).
Thereafter, the liquid crystal display device is completed in the same manner as in the first embodiment.

  Next, the configuration of the third embodiment of the liquid crystal display device of the present invention will be described.

FIG. 6 is a plan view of one pixel portion of the TFT substrate used in the third embodiment. FIGS. 7, 8, 11 and 12 show the order of manufacturing steps of the TFT substrate used in the liquid crystal display device of this embodiment. A manufacturing process sectional view is illustrated. Here, FIGS. 11 and 12 show a TFT portion and a pixel portion (see FIG. 6).
A-A line), a signal line terminal portion (BB line in FIG. 1), and a scanning line terminal portion (CC line in FIG. 1). TF used in liquid crystal display devices
The manufacturing process of T board | substrate is illustrated. The third embodiment is another example of a liquid crystal display device having an inverted stagger channel etch type TFT substrate manufactured using four masks.
In the third embodiment, the second step of the TFT substrate manufacturing method of the second embodiment is changed, and the configuration is exactly the same as that of the second embodiment.

  Next, a third embodiment of the method for manufacturing a liquid crystal display device of the present invention will be described.

The manufacturing method of the TFT substrate used in the third embodiment is similar to that of the second embodiment (a
) A step of forming a gate electrode and a scanning line on a transparent insulating substrate; (b) a step of forming a gate insulating film, a source, a drain electrode and a signal line, and a semiconductor layer; and (c) forming a passivation film and a contact hole. And (d) forming a pixel electrode. Here, in the step (b), the source, drain electrodes and signal lines are formed in a three-layer structure of a refractory metal layer, an Al (alloy) layer and a refractory metal layer, and are protected on the side surfaces of the Al (alloy) layer. It is characterized by forming a film and evacuating in the same vacuum after dry etching at the time of forming a semiconductor layer and a channel.

Since the manufacturing method other than the second step (step (b)) is exactly the same as in the second embodiment, only the second step will be described. 11-12 is sectional drawing explaining the process of FIG.7 (b) of 3rd Embodiment.

Three layers of a refractory metal layer 1, an Al (alloy) layer 2, and a refractory metal layer 3 laminated on a three-layer film composed of a gate insulating film 22, an a-Si layer 28 and an n + -type a-Si layer 29. A photoresist is applied on the film 4, exposure and development are performed, and the photoresist 54 is patterned in a staircase pattern with a predetermined pattern. At this time, exposure uses a halftone mask or a gray tone mask,
The photoresist 54 is thinly formed only in a region to be a channel, and is thickly formed on a portion to be a source / drain electrode and a portion to be a terminal portion metal film of a signal line and a signal line terminal (FIG. 11).
(A)).

Next, the refractory metal layer 3, the Al (alloy) layer 2, and the three-layer film 4 of the refractory metal layer 1 are etched using the photoresist 54 as a mask, and then the n + -type a-Si layer 29 and a- Si
The layer 28 is etched (FIG. 11B). As in the first embodiment, the signal line metal film is etched by wet etching and side-etched from the end face of the photoresist 54. Further, washing with water after etching is performed with warm water of 40 ° C. to 50 ° C., and a protective film 38 made of an Al (alloy) oxide film or a hydroxide film is formed on the side wall of the Al (alloy) film 2. Also,
The etching method of the semiconductor layer 23 is the same as that of the second embodiment. After the etching, evacuation is performed in a state where the substrate is separated from the electrode in the same vacuum, and further, O ₂ , N ₂ , H ₂ , He Plasma treatment is performed with any of these gases.

Next, O ₂ plasma treatment is performed, and the photoresist 55 is entirely ashed to remove the thin portion (FIG. 12A). This O ₂ plasma treatment is desirably performed continuously in the same vacuum after etching the semiconductor layer. After the semiconductor layer is etched, if it is opened to the atmosphere, it is immediately washed with water.

Next, using the photoresist 55 as a mask, a part of the refractory metal layer 3, A to be a channel,
Etch the three-layer film of l (alloy) layer 2 and refractory metal layer 1,
The + type a-Si layer 29 is removed by etching (FIG. 12B). The method for etching the signal line metal film in the channel portion is the same as in the first embodiment, and is performed by wet etching and side-etched from the end face of the photoresist 55. In addition, wash with water after etching.
A protective film 38 made of an Al (alloy) oxide film or a hydroxide film is formed on the side wall of the Al (alloy) film 2 by performing hot water at 0 ° C. to 50 ° C. The method for etching the n + -type a-Si layer in the channel portion, evacuation after etching, and plasma treatment are the same as in the first embodiment.

Subsequently, as in the first embodiment, the photoresist 55 is quickly removed by wet peeling, and the source electrode 24, the drain electrode 25, the signal line 12, and the terminal portion metal film 3 of the signal line terminal.
4 and the semiconductor layer 23 are formed (FIG. 12C). Thereafter, as in the second embodiment, a passivation film and a contact hole are formed, and further a pixel electrode is formed. In this embodiment, the end face of the signal line metal film and the end face of the semiconductor layer in FIG. Does not match
It is stepped as shown in FIG.

By using the method as described above, the Al (alloy) film is not exposed to the plasma of the etching gas, and F and Cl attached to the substrate can be removed, so that corrosion of Al can be prevented. it can.

In addition, although the example which forms a protective film by warm water washing at the time of water washing after wet etching of the signal line metal film of the portion which becomes a channel is described here, at the time of water washing after peeling of the photoresist,
Similarly, warm water washing may be performed. In this case, the above-described dry etching for forming the channel is performed using the metal films of the source and drain electrodes as a mask.

  Next, the configuration of the fourth embodiment of the method for manufacturing a liquid crystal display device of the present invention will be described.

FIG. 13 is a plan view of one pixel portion of the TFT substrate used in the fourth embodiment.
5 is a cross-sectional view of a manufacturing process in the order of the manufacturing process of the TFT substrate used in the present embodiment. 14 and 15 show a TFT portion, a pixel portion (A-A line in FIG. 13), a signal line terminal portion (
FIG. 2 is a cross-sectional view taken along a line BB in FIG. 1 and a scanning line terminal portion (a line CC in FIG. 1), and shows a manufacturing process of a TFT substrate used in the liquid crystal display device of the present embodiment. It is illustrated. The fourth embodiment is an example of a liquid crystal display device having an inverted stagger channel protection type TFT substrate manufactured using five masks.

The TFT substrate shown in FIG. 13 and FIG. 15B is the gate electrode 2 on the transparent insulating substrate 20.
1. a scanning line 11 connected to the gate electrode 21, a storage capacitor electrode 31 sharing the previous scanning line,
The light shielding layer 32 and the terminal part metal film 33 of the scanning line terminal 14 are included. A gate insulating film 22 is provided on the gate electrode 21, a semiconductor layer 23 and a channel protective film 61 are provided on the gate insulating film 22 so as to face the gate electrode 21, and a source electrode 24 and a drain electrode are provided thereon. 25
Are formed separately. The difference from the second embodiment is that a channel protective film is formed. A passivation film 26 is formed on the source electrode 24, the drain electrode 25, the signal line 12 connected to the drain electrode 25 provided on the gate insulating film 22, and the terminal metal film 34 of the signal line terminal 15. The pixel portion contact hole 35 and the terminal portion contact hole 36 are provided in a part of the passivation film 26. The pixel electrode 27 and the terminal part metal film 33 connected to the source electrode 24 through the contact holes 35 and 36,
A connection electrode 37 is provided to connect to 34. Here, the storage capacitor electrode 31 and the pixel electrode 2
A storage capacitor is formed between the first and second storage capacitors.

Further, as shown in FIG. 15B, in the TFT substrate used in the liquid crystal display device of the present embodiment, the source electrode 24, the drain electrode 25, the signal line 12, and the terminal portion metal film 34 of the signal line terminal are: The lower layer has a laminated structure of a refractory metal layer, an Al (alloy) layer, and a refractory metal layer, and a protective film 38 is formed on the side surface of the Al (alloy) layer.

  Next, a fourth embodiment of the method for manufacturing a liquid crystal display device of the present invention will be described.

The TFT substrate manufacturing method used in the fourth embodiment includes (a) a step of forming a gate electrode and a scanning line on a transparent insulating substrate, (b) a gate insulating film, an a-Si layer, and a channel protective film. A step of forming, (c) a step of forming a source, drain electrode, signal line, and semiconductor layer, (d
A step of forming a passivation film and a contact hole, and a step of forming a pixel electrode. Here, in the step (c), the source, drain electrodes and signal lines are formed in a three-layer structure of a refractory metal layer, an Al (alloy) layer and a refractory metal layer, and are protected on the side surfaces of the Al (alloy) layer. It is characterized by forming a film and evacuating in the same vacuum after dry etching at the time of forming a semiconductor layer and a channel.

14 to 15, first, an Al (alloy) layer having a thickness of about 200 nm and a thickness of about 100 are formed on a transparent insulating substrate 20 made of non-alkali glass having a thickness of 0.7 mm by sputtering.
A refractory metal layer having a thickness of nm is formed, and the gate electrode 2 is formed by photolithography and etching.
1. A scanning line (not shown), a storage capacitor electrode (not shown), a light shielding layer (not shown), and a terminal metal film 33 of the scanning line terminal are formed (FIG. 14A). Here, the types of Al (alloy) and the refractory metal and the etching method are the same as those in the first embodiment.

Next, a gate insulating film 22 made of a silicon nitride film having a thickness of about 400 nm, an amorphous silicon (a-Si) layer 28 having a thickness of about 80 nm, and a silicon nitride film having a thickness of about 100 nm are sequentially formed by plasma CVD. Then, a channel protective film 61 is formed to face the gate electrode 21 by photolithography and etching (FIG. 14B).

Next, an N-type amorphous silicon (n + -type a-Si) layer 29 doped with phosphorus of about 30 nm thickness by plasma CVD, a refractory metal layer of about 50 nm thickness, and an Al of 200 nm thickness by sputtering. An (alloy) layer and a refractory metal layer having a thickness of about 100 nm are sequentially formed, and by photolithography and etching, the source electrode 24, the drain electrode 25, the signal line 12, the terminal line metal film 34 of the signal line terminal, and the semiconductor The layer 23 is formed (FIG. 14C). In this etching, the photoresist is used as a mask to etch the refractory metal layer, the Al (alloy) layer, and the refractory metal layer, and then the n + -type a-Si layer 29 and the a-Si layer 28 are etched. To do. As in the first embodiment, the signal line metal film is etched by wet etching and side-etched from the end face of the photoresist. Further, water washing after etching is performed with hot water of 40 ° C. to 50 ° C. to form a protective film 38 made of an Al (alloy) oxide film or a hydroxide film on the side wall of the Al (alloy) film. The method for etching the semiconductor layer is the same as in the second embodiment. After etching, the substrate is separated from the electrode in the same vacuum, and further, O ₂ , N ₂ , H ₂ , Plasma treatment is performed with any gas of He. At the time of etching the semiconductor layer 23, the n + -type a-Si layer 29 in the channel portion is also etched away. Subsequently, as in the first embodiment, the photoresist is quickly removed by wet stripping.

By using the method as described above, the Al (alloy) film is not exposed to the plasma of the etching gas, and F and Cl attached to the substrate can be removed, so that corrosion of Al can be prevented. it can.

Here, an example in which the protective film is formed by washing with warm water at the time of washing with water after wet etching of the signal line metal film has been described. However, washing with warm water may be similarly performed at the time of washing with water after peeling off the photoresist. In this case, the above-described dry etching for forming the channel and the semiconductor layer is performed using the metal films of the source and drain electrodes as a mask.

Next, a passivation film 26 made of a silicon nitride film having a thickness of about 200 nm is formed by plasma CVD, and a pixel portion contact hole 35 and a terminal portion contact hole 36 are opened by photolithography and etching (FIG. 15A). ).

Next, a transparent conductive film made of ITO or IZO having a thickness of about 50 nm is formed by sputtering, the pixel electrode 27 and the connection electrode 37 of the terminal portion are formed by photolithography and etching, and annealed at a temperature of about 270 ° C. Thus, the TFT substrate is completed (FIG. 15B).

  Thereafter, the liquid crystal display device is completed in the same manner as in the first embodiment.

  Next, data that is the basis of the present invention will be described based on experimental results.

Table 1 shows the presence / absence of a photoresist serving as a mask and a protection treatment for the side surface of the signal line Al (by hot water washing) in the channel portion n + type a-Si layer dry etching for the TFT substrate sample of the first embodiment. The results of examining the relationship between the presence / absence of oxidation and hydroxylation) and the type of etching gas and the occurrence of signal line Al corrosion are collectively shown. Each sample may be dry etched with Cl ₂ / O ₂ , two-step etched with CH F ₃ / He / O ₂ and SF ₆ / HCl / He, or CH F ₃ / He / O ₂ and SF ₆ / Dry etching by two-step etching with CHF ₃ / He was performed. The vacuum after the etching and the O ₂ plasma treatment were not performed, and the sample was taken out into the atmosphere as it was. The signal line Al corrosion was observed with an optical microscope after the substrate was taken out of the chamber after dry etching and left in the atmosphere for about 1 hour. In addition, the symbols in the table including Table 2 and Table 3 are as follows.
XX: Al corrosion occurs in large quantities.
X: Al corrosion occurred.
Δ: Al corrosion slightly occurred.
○: Al corrosion does not occur.

Similarly, Table 2 shows that the sample of the TFT substrate of the first embodiment was subjected to the vacuum drawing time after the etching and the subsequent O ₂ plasma treatment in the channel portion n + type a-Si layer dry etching. The relationship between time and the occurrence of signal line Al corrosion is shown together. The samples in Table 2 were etched in two steps with CHF ₃ / He / O ₂ and SF ₆ / HCl / He without a photoresist and without protection of the side surface of the signal line Al. is there. The signal line Al corrosion was observed with an optical microscope after being taken out of the substrate after dry etching and left in the atmosphere for about 1 hour.

Similarly, Table 3 shows that the sample of the TFT substrate of the first embodiment was cleaned (wet stripping) after the substrate was opened to the atmosphere after the channel portion n + -type a-Si layer dry etching.
The result of investigating the relationship between the elapsed time until the occurrence and the occurrence of signal line Al corrosion is shown. In each sample, CHF ₃ / He / O ₂ and S are not subjected to protection processing of the side surface of the signal line Al.
Two-step etching with F ₆ / HCl / He was performed, and vacuuming after etching and O ₂ plasma treatment were not performed. Signal line Al corrosion was observed with an optical microscope after wet stripping of the photoresist mask.

According to the above experiment, chlorine gas (Cl ₂ , HCl) is more Al than fluorine gas (CHF ₃ ).
It was confirmed that corrosion was likely to occur and that Al corrosion occurred even without using chlorine gas. It has been found that these Al corrosions are considerably suppressed by etching in the presence of a photoresist or performing a protective treatment on the Al side surface, and can be prevented by performing both simultaneously. Furthermore, the longer the evacuation time after etching and the longer the O ₂ treatment time, the more A
It has been found that there is an effect on 1 corrosion, and similarly, the shorter the standing time until the cleaning process after etching, the more effective against Al corrosion.

Therefore, as countermeasures against Al corrosion, it is important not to expose the Al side surface of the signal line to the etching gas plasma, and to remove and replace the Cl and F components of the etching gas remaining on the substrate. It was confirmed that the effect of improving Al corrosion was further increased by combining them.

In the above-described embodiment, an example in which the present invention is applied to a twisted nematic (TN) type liquid crystal display device has been described. However, it goes without saying that the present invention can be applied to an in-plane switching (IPS) type liquid crystal display device. In the IPS liquid crystal display device, the pixel electrode is usually formed of a metal film. However, in the TFT substrate as shown in the embodiment, the connection electrode of the terminal portion, the bundling of the common wiring, the gate layer and the drain of the protection transistor portion This is because the transparent conductive film on the passivation film is used for layer conversion with the layer, so that the manufacturing process flow is the same for both the TN type and the IPS type. Further, even in an IPS type liquid crystal display device, there is a technique of forming a pixel electrode and a common electrode with a transparent conductive film on a passivation film in order to improve an aperture ratio, and the present invention can be applied to such a liquid crystal display device. Is obvious.

In the above-described embodiment, the example in which the protection treatment of the Al side surface is performed by washing with warm water is shown.
Although the number of steps is increased by one step, an Al oxide film or a nitride film may be formed by performing plasma treatment with oxygen or nitrogen. However, in this case, it is necessary to perform plasma processing in an isotropic PE mode and to form the protective film with a thickness in the lateral direction of at least 100 nm or more. This is because if the thickness of the protective film in the lateral direction is about several tens of nanometers or less, the dry etching gas easily penetrates into the inside from the defective portion of the film and the protective effect is not sufficient.

In the above-described embodiment, an example in which the signal line is applied to a three-layer laminated wiring of refractory metal / Al (alloy) / refractory metal is shown. It is also applicable to. In this case, a TFT structure in which the pixel electrode is formed below the signal line may be employed.

In the above-described embodiment, an example of the a-Si TFT is shown. However, polysilicon (p-S
i) Needless to say, the present invention can also be applied to TFTs.

As described above, according to the preferred embodiment of the present invention, after the formation of the signal line, the source, and the drain electrode, the side surface of the Al (alloy) film exposed on the side of the signal line, the source, and the drain electrode is defined as A.
Al (alloy) caused by chlorine gas or fluorine gas during subsequent semiconductor layer etching or channel etching to protect with l (alloy) oxide film or hydroxide film protective film
Corrosion of the film can be suppressed. In addition, since the metal film of the signal line, source and drain electrodes has receded from the photoresist which is an etching mask, it is difficult to be exposed to plasma of chlorine gas or fluorine gas during etching of the semiconductor layer or channel etching. (
Alloy) Corrosion of the film can be suppressed.

Further, in the semiconductor layer etching and channel etching processes, after the dry etching is completed, evacuation is performed in the same vacuum, and further, plasma treatment is performed with any one gas of O ₂ , N ₂ , H ₂ , and He, thereby forming a substrate on the substrate. The fluorine-based gas and chlorine-based gas remaining in the substrate are removed and replaced, so that the chlorine-based gas and fluorine-based gas adhering to the substrate during the etching of the semiconductor layer and the channel etching can be efficiently removed, and the Al (alloy) film Corrosion can be suppressed.
Further, in the semiconductor layer etching and channel etching process, the fluorine gas and chlorine gas remaining on the substrate are removed by setting the time from the completion of dry etching to the cleaning process within 10 minutes, so that the semiconductor layer The chlorine-based gas and fluorine-based gas adhering to the substrate at the time of etching and channel etching can be removed, and corrosion of the Al (alloy) film can be suppressed.

It is a conceptual diagram which shows the structure of the thin-film transistor array board | substrate (TFT board | substrate) used for the liquid crystal display device of this invention. It is a top view of 1 pixel part of the TFT substrate used for 1st Embodiment of the manufacturing method of the liquid crystal display device of this invention. FIG. 2 illustrates manufacturing process cross-sectional views in the order of manufacturing processes of a TFT substrate used in the first embodiment of the method for manufacturing a liquid crystal display device of the present invention. FIG. 4 is a manufacturing process cross-sectional view illustrating a manufacturing process following FIG. 3. FIG. 5 is a manufacturing process cross-sectional view showing the manufacturing process following FIG. 4. It is a top view of 1 pixel part of the TFT substrate used for the 2nd, 3rd embodiment of the manufacturing method of the liquid crystal display device of this invention. The manufacturing process sectional drawing of the order of the manufacturing process of the TFT substrate used in the 2nd, 3rd embodiment of the manufacturing method of the liquid crystal display device of this invention is illustrated. FIG. 8 is a manufacturing process cross-sectional view showing the manufacturing process following FIG. 7. It is manufacturing process sectional drawing explaining the process of FIG.7 (b) of 2nd Embodiment of the manufacturing method of the liquid crystal display device of this invention in detail. FIG. 10 is a manufacturing process sectional view showing the manufacturing process, following FIG. 9; It is manufacturing process sectional drawing explaining the process of FIG.7 (b) of 3rd Embodiment of the manufacturing method of the liquid crystal display device of this invention in detail. FIG. 12 is a manufacturing process cross-sectional view showing the manufacturing process following FIG. 11. It is a top view of 1 pixel part of the TFT substrate used for 4th Embodiment of the manufacturing method of the liquid crystal display device of this invention. The manufacturing process sectional drawing of order of the manufacturing process of the TFT substrate used in 4th Embodiment of the manufacturing method of the liquid crystal display device of this invention is illustrated. FIG. 15 is a manufacturing process cross-sectional view showing the manufacturing process following FIG. 14.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3 Refractory metal layer 2 Al (alloy) layer 4 3 layer film 10 TFT substrate 11 Scan line 12 Signal line 13 Thin film transistor (TFT)
DESCRIPTION OF SYMBOLS 14 Scan line terminal 15 Signal line terminal 20, 50 Transparent insulating substrate 21 Gate electrode 22 Gate insulating film 23 Semiconductor layer 24 Source electrode 25 Drain electrode 26 Passivation film 27 Pixel electrode 28 Amorphous silicon (a-Si type) layer 29 N type Amorphous silicon (n + type a-Si) layer 31 Storage capacitor electrode 32 Light shielding layer 33, 34 Terminal part metal film 35 Pixel part contact hole 36 Terminal part contact hole 37 Connection electrode 38 Protective film 40 Opposite substrate 41 Alignment film 42 Color filter 43 Black matrix 44 Common electrode 45 Seal 46 Liquid crystal 47 Deflection plate 51, 52, 53, 54, 55 Photo resist 61 Channel protective film

Claims (4)

A method of manufacturing a liquid crystal display device, wherein a semiconductor layer and a laminated metal film of a refractory metal film and a low resistance metal film are patterned on a substrate,
Forming a photoresist pattern on the laminated metal film, etching the laminated metal film using the photoresist as a mask, and forming the laminated metal film pattern;
Dry etching part or all of the semiconductor layer using the photoresist or the laminated metal film as a mask,
After the dry etching, the method further includes a step of evacuating a chamber for housing the substrate, and a step of performing a plasma treatment on the substrate after the step of performing the evacuation, and the step of performing the evacuation and the plasma treatment An etching gas remaining on the substrate is removed by the step of performing the method of manufacturing a liquid crystal display device.   The method of manufacturing a liquid crystal display device according to claim 1, wherein the evacuation is performed in a state where the substrate is separated from the electrode of the chamber.   The method of manufacturing a liquid crystal display device according to claim 1, wherein the evacuation is performed for 120 seconds or more. 4. The method of manufacturing a liquid crystal display device according to claim 1, wherein the plasma treatment is performed with any gas of O ₂ , N ₂ , H ₂ , and He. 5.

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