JP4892822B2 - Manufacturing method of electro-optical device - Google Patents

Description

  The present invention relates to a method for manufacturing a thin film transistor, an electro-optical device, and an electronic apparatus.

In an active matrix liquid crystal display device, a switching element is provided for each pixel, and a switching operation of each pixel is performed via the switching element. As the switching element, for example, a TFT (Thin Film Transistor) is used. Various TFT structures using amorphous silicon as the semiconductor layer are known, but a bottom gate structure (inverted staggered structure) in which a gate electrode is provided between the semiconductor layer and the substrate is often used. For example, Patent Document 1 discloses a method for efficiently manufacturing a bottom-gate TFT while protecting it from electrostatic breakdown. In the TFT manufacturing method described in Patent Document 1, first, a gate electrode is patterned on a substrate, a gate insulating film covering the gate electrode is formed, and an amorphous silicon layer and an N-type are formed on the gate insulating film. A silicon layer is stacked. Thereafter, the N-type silicon layer is partially removed to form two N-type silicon layers separated from each other on the amorphous silicon layer, and electrically connected to the N-type silicon layers, respectively. A source electrode and a drain electrode are formed.
Japanese Patent No. 3261699

  According to the technique described in the above prior art document, there can be obtained an advantage that a TFT having high reliability can be manufactured with a small number of steps. However, when such a manufacturing method is used, there is a limitation that a heating process that reaches 300 ° C. cannot be performed after the formation of the semiconductor layer (amorphous silicon layer and N-type silicon layer). The means for forming the light-transmitting conductive film) cannot be easily changed, which is an obstacle to further cost reduction.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method of manufacturing a thin film transistor capable of realizing a reduction in manufacturing cost without departing from the limit range of the substrate heating temperature. .

In order to solve the above problems, a method for manufacturing an electro-optical device according to the present invention includes a scanning line, a data line, a thin film transistor provided at an intersection of the scanning line and the data line, an external circuit, and a substrate. A mounting terminal to be connected, wherein the thin film transistor has a semiconductor layer and an electrode film, and is a method of forming the semiconductor layer on the substrate, and corresponds to the electrode member Surrounding the first region and forming a bank surrounding the second region corresponding to the mounting terminal; applying a liquid material to the first region and the second region; and drying the liquid material, Forming the electrode film in the first region and forming the mounting terminal in the second region.
The method of manufacturing an electro-optical device according to the present invention is the above-described manufacturing method, wherein the bank includes a first bank portion provided in a region overlapping the semiconductor layer, and a second bank portion surrounding the semiconductor layer. May further be included.
The electro-optical device manufacturing method of the present invention is the manufacturing method described above, wherein one or more metal materials selected from Ni, Ti, W, and Mn are provided after the step of forming the electrode film. And coating the first region and the second region to form a coated metal film.
The electro-optical device manufacturing method of the present invention is the manufacturing method described above, further comprising a step of forming an intermediate layer containing titanium oxide on the electrode film before the step of forming the coated metal film. May be.
The electro-optical device manufacturing method of the present invention is the manufacturing method described above, wherein the electrode film is a source electrode or a gate electrode of the thin film transistor, and the electrode film is formed simultaneously with the mounting terminal. Also good.
The electro-optical device manufacturing method of the present invention is the manufacturing method described above, wherein the electrode film is the scanning line or the data line, and the electrode film may be formed simultaneously with the mounting terminal. Good.
In order to solve the above-described problems, the present invention provides a method of manufacturing a thin film transistor including a semiconductor layer formed on a substrate and an electrode member, wherein the electrode is performed after the semiconductor layer is formed on the substrate. The step of forming a member is a step of forming the electrode member made of a metal material using a liquid phase method, and the firing temperature of the electrode member in the step is 250 ° C. or less, Provide a method.

  In the method for manufacturing a thin film transistor of the present invention, the step of forming the electrode member on the substrate includes a step of forming a bank surrounding the formation region of the electrode member by a liquid phase method. The curing temperature is preferably 250 ° C. or lower. When the electrode member is formed by using a liquid phase method, it is preferable to form a bank for holding the liquid material for forming the electrode member at a predetermined position on the substrate. Excessive heating may cause hydrogen desorption in the semiconductor layer. Therefore, by setting the bank curing temperature to 250 ° C. or lower as in the present manufacturing method, it is possible to prevent hydrogen desorption from the semiconductor layer and to manufacture a thin film transistor with excellent operational reliability.

In the method for manufacturing a thin film transistor of the present invention, the step of forming the electrode member includes a step of forming a barrier layer made of a metal material on the substrate using a liquid phase method, and a liquid phase method on the barrier layer. And forming a base layer made of a metal material, and the barrier layer is preferably formed using one or more metal materials selected from Ni, Ti, W, and Mn. .
According to this manufacturing method, the barrier layer formed in the lower layer of the electrode member can prevent the material constituting the base layer from diffusing into the adjacent layers in the thin film transistor laminated structure. Thus, it is possible to prevent the performance degradation and the characteristic change of the thin film transistor from occurring.

In the method for producing a thin film transistor of the present invention, the step of forming the electrode member includes a step of forming a base layer made of a metal material on the substrate using a liquid phase method, and a liquid phase method on the base layer. And forming a coating layer made of a metal material, and the coating layer is preferably formed using one or more metal materials selected from Ni, Ti, W, and Mn. .
According to this manufacturing method, the covering layer formed on the upper layer of the electrode member can prevent the material constituting the base layer from diffusing into the adjacent layers in the laminated structure of the thin film transistor. Accordingly, malfunction and characteristic shift of other semiconductor elements mounted on the electronic device together with the thin film transistor can be prevented, and a thin film transistor that can constitute an electronic device having excellent operation reliability can be manufactured.

  In the method for manufacturing a thin film transistor of the present invention, it is preferable that the base layer is formed using one or more metal materials selected from Ag, Cu, and Al. By using these materials, an electrode member having good conductivity can be easily formed even at a firing temperature of 250 ° C. or lower.

  In the thin film transistor manufacturing method of the present invention, it is preferable to form a source electrode and / or a drain electrode of the thin film transistor by forming a laminated structure of the barrier layer and the base layer. According to this manufacturing method, it is possible to manufacture a thin film transistor that can prevent the constituent elements of the base layer from diffusing into the adjacent layer even in the source electrode or the drain electrode.

  In the thin film transistor manufacturing method of the present invention, a step of forming a gate electrode on the substrate, a step of forming a gate insulating film on the gate electrode, and a step of forming the semiconductor layer on the gate insulating film Preferably, the step of forming the gate electrode is a step of forming a laminated structure of the base layer and the coating layer. According to this configuration, since the covering layer is disposed on the semiconductor layer side of the gate electrode, the constituent elements of the base layer constituting the gate electrode diffuse into the gate insulating film provided between the semiconductor layer and the semiconductor layer. Thus, a thin film transistor that can be prevented from being manufactured can be manufactured, and a thin film transistor having excellent operation reliability can be obtained.

  In the thin film transistor manufacturing method of the present invention, it is preferable to form a source electrode and / or a drain electrode of the thin film transistor by forming a laminated structure of the base layer and the covering layer. According to this manufacturing method, it is possible to manufacture a thin film transistor that can prevent the constituent elements of the base layer from diffusing into the adjacent layer even in the source electrode or the drain electrode.

  The electro-optical device of the present invention includes a thin film transistor obtained by the manufacturing method of the present invention described above. According to this configuration, an electro-optical device that includes a switching element excellent in operation reliability and can be manufactured at low cost is provided.

  An electronic apparatus according to the present invention includes the electro-optical device according to the present invention described above. According to this configuration, an electronic device that has excellent reliability and can be provided at low cost can be obtained.

(Liquid crystal display device)
FIG. 1 is an equivalent circuit diagram showing a liquid crystal display device 100 which is an embodiment of the electro-optical device of the present invention. In the liquid crystal display device according to the present embodiment, a pixel electrode 19 and a TFT 60 that is a switching element for controlling the pixel electrode 19 are respectively formed on a plurality of dots arranged in a matrix that forms an image display region. The data line (electrode wiring) 16 to which the image signal is supplied is electrically connected to the source of the TFT 30. Image signals S1, S2,..., Sn to be written to the data lines 16 are supplied line-sequentially in this order, or are supplied for each group to a plurality of adjacent data lines 16. Further, the scanning line (electrode wiring) 18a is electrically connected to the gate of the TFT 60, and the scanning signals G1, G2,... Applied. Further, the pixel electrode 19 is electrically connected to the drain of the TFT 60. By turning on the TFT 60, which is a switching element, for a predetermined period, the image signals S1, S2,. Write at the timing.

  Image signals S1, S2,..., Sn written at a predetermined level on the liquid crystal via the pixel electrode 19 are held for a certain period with a common electrode described later. Then, the light is modulated by utilizing the change in the orientation and order of the molecular assembly of the liquid crystal according to the applied voltage level, thereby enabling arbitrary gradation display. Each dot is provided with a storage capacitor 70 in parallel with the liquid crystal capacitor formed between the pixel electrode 19 and the common electrode in order to prevent the image signal written in the liquid crystal from leaking. Reference numeral 18b denotes a capacitor line connected to an electrode on one side of the storage capacitor 70.

  Next, FIG. 2 is an overall configuration diagram of the liquid crystal display device 100. The liquid crystal display device 100 has a configuration in which the TFT array substrate 10 and the counter substrate 25 are bonded together via a sealing material 52 having a substantially rectangular frame shape in plan view, and is sandwiched between the substrates 10 and 25. The liquid crystal thus formed is sealed between the substrates by a sealing material 52. In FIG. 2, the outer peripheral end of the counter substrate 25 is displayed so as to coincide with the outer peripheral end of the sealing material 52 in plan view.

  In a region inside the sealing material 52, a light shielding film (peripheral parting) 53 made of a light shielding material is formed in a rectangular frame shape. In the peripheral circuit area outside the sealing material 52, the data line driving circuit 201 and the mounting terminal 202 are disposed along one side of the TFT array substrate 10, and scanning is performed along two sides adjacent to the one side. Line drive circuits 104 and 104 are provided. On the remaining one side of the TFT array substrate 10, a plurality of wirings 105 are formed for connecting the scanning line driving circuits 104, 104. In addition, a plurality of inter-substrate conductive members 106 for providing electrical continuity between the TFT array substrate 10 and the counter substrate 25 are disposed at corner portions of the counter substrate 25.

  Next, FIG. 3 is a plan configuration diagram illustrating a pixel configuration of the liquid crystal display device 100. As shown in FIG. 3, in the display area of the liquid crystal display device 100, a plurality of scanning lines 18a extend in the left-right direction in the figure, and a plurality of data lines 16 extend in a direction intersecting these scanning lines. is doing. In FIG. 3, a rectangular area in plan view surrounded by the scanning lines 18a and the data lines 16 is a dot area. A color filter of one of the three primary colors is formed corresponding to one dot region, and one pixel region having three colored portions 22R, 22G, and 22B is formed by the three dot regions shown. These colored portions 22R, 22G, and 22B are periodically arranged in the display area of the liquid crystal display device 100.

  In each dot region shown in FIG. 3, a pixel electrode 19 having a substantially rectangular shape in plan view made of a light-transmitting conductive film such as ITO (indium tin oxide) is provided. A TFT 60 is interposed between the data line 16 and 18a. The TFT 60 includes a semiconductor layer 33, a gate electrode 80 a provided on the lower layer side (substrate side) of the semiconductor layer 33, a source electrode 34 provided on the upper layer side of the semiconductor layer 33, and a drain electrode 35. Has been. A channel region of the TFT 30 is formed in a region where the semiconductor layer 33 and the gate electrode 80a face each other, and a source region and a drain region are formed in the semiconductor layers on both sides thereof.

The gate electrode 80 a is formed by branching a part of the scanning line 18 a in the extending direction of the data line 16, and the semiconductor layer 33 and an unillustrated insulating film (gate insulating film) are interposed at the tip of the gate electrode 80 a. It faces the vertical direction of the page. The source electrode 34 is formed by branching a part of the data line 16 in the extending direction of the scanning line 18a, and is electrically connected to the semiconductor layer 33 (source region). One end (left end in the drawing) side of the drain electrode 35 is electrically connected to the semiconductor layer 33 (drain region), and the other end (right end in the drawing) side of the drain electrode 35 is electrically connected to the pixel electrode 19. ing.
In the above configuration, the TFT 60 is turned on for a predetermined period by a gate signal input via the scanning line 18a, whereby an image signal supplied via the data line 16 is supplied to the liquid crystal at a predetermined timing. On the other hand, it functions as a switching element for writing.

  FIG. 4 is a cross-sectional configuration diagram of the TFT array substrate 10 taken along line B-B ′ of FIG. 3. Looking at the cross-sectional structure shown in the figure, the TFT array substrate 10 is mainly composed of the TFT 60 formed on the inner surface side (the upper surface side in the drawing) of the glass substrate P and the pixel electrode 19. On the glass substrate P, a bank 30 partially opened is formed, and a gate electrode 80 a is embedded in the opening of the bank 30. The gate electrode 80a includes a first electrode layer (base layer) 81 made of a metal material such as Ag, Cu, or Al and a second electrode layer made of a metal material such as Ni, Ti, W, or Mn on the glass substrate P. (Coating layer) 82 is laminated.

A gate insulating film 83 made of silicon oxide, silicon nitride, or the like is formed in a region including the gate electrode 80a on the bank 30, and the semiconductor is positioned on the gate insulating film 83 so as to overlap the gate electrode 80a in a plane. A layer 33 is formed. The semiconductor layer 33 includes an amorphous silicon layer 84 and an N ⁺ silicon layer 85 stacked on the amorphous silicon layer 84. N ⁺ silicon layer 85, on the amorphous silicon layer 84 is divided into two portions which are planarly spaced, whereas N ⁺ silicon layer 85 (left side), the gate insulating film 83 above and the N ⁺ The source electrode 34 formed over the silicon layer 85 is electrically connected, and the other N ⁺ silicon layer 85 is a drain formed over the gate insulating film 83 and the N ⁺ silicon layer 85. The electrode 35 is electrically connected.

  The source electrode 34 is a conductive member having a three-layer structure in which a barrier metal film (barrier layer) 61a, a source electrode film (base layer) 66, and a covering metal film (covering layer) 68a are stacked. Reference numeral 35 denotes a conductive member having a three-layer structure in which a barrier metal film (barrier layer) 61a, a drain electrode film (base layer) 67, and a covering metal film (covering layer) 68a are laminated. The barrier metal film 61a is formed using one or more metal materials selected from Ni (nickel), Ti (titanium), W (tungsten), Mn (manganese), and the like. The electrode film 67 is formed using one or more metal materials selected from Ag (silver), Cu (copper), Al (aluminum), and the like, and the coated metal film 68a includes the barrier metal film 61a and Similarly, it is formed using one or more metal materials selected from Ni, Ti, W, Mn and the like.

  As shown in FIG. 3, since the data line 16 and the source electrode 34, and the scanning line 18a and the gate electrode 80a are integrally formed, the data line 16 has the same three layers as the source electrode 34. The scanning line 18a is a conductive member having a two-layer structure similar to the gate electrode 80a.

  A bank 31 c is formed so as to cover a part of the surface of the drain electrode 35 and the source electrode 34. The banks 31c are actually formed on the glass substrate P in a substantially lattice shape in plan view having openings corresponding to the respective pixel electrodes 19 shown in FIG. Sometimes, it is used as a partition member for patterning the pixel electrode 19 using a liquid phase method. As shown in FIG. 4, the pixel electrode 19 is formed so as to be in contact with the upper surface and the side surface of the drain electrode 35 protruding from the insulating film 31 c to the right side in the drawing, and is electrically connected to the drain electrode 35.

  In practice, an alignment film for controlling the initial alignment state of the liquid crystal is formed on the surface of the pixel electrode 19 and the insulating film 31c, and enters the liquid crystal layer on the outer surface side of the glass substrate P. A phase difference plate and a polarizing plate for controlling the polarization state of light are provided. Further, a backlight used as illumination means in the case of a transmissive or transflective liquid crystal display device is provided on the outer side (panel back side) of the TFT array substrate 10.

  Although the detailed illustration of the counter substrate 25 is omitted, the colored portions 22R, 22G, and 22B shown in FIG. 3 are arrayed on the inner surface (the surface facing the TFT array substrate) of the same substrate as the glass substrate P. And a counter electrode made of a flat solid light-transmitting conductive film. An alignment film similar to that of the TFT array substrate is formed on the counter electrode, and a retardation plate and a polarizing plate are provided on the outer surface side of the substrate as necessary.

  The liquid crystal layer sealed between the TFT array substrate 10 and the counter substrate 25 is mainly composed of liquid crystal molecules. As the liquid crystal molecules constituting the liquid crystal layer, any liquid crystal molecules may be used as long as they can be aligned, such as nematic liquid crystals and smectic liquid crystals. In the case of a TN type liquid crystal panel, those that form nematic liquid crystals are preferable. For example, phenylcyclohexane derivative liquid crystal, biphenyl derivative liquid crystal, biphenyl cyclohexane derivative liquid crystal, terphenyl derivative liquid crystal, phenyl ether derivative liquid crystal, phenyl ester derivative liquid crystal, bicyclohexane derivative liquid crystal, azomethine derivative liquid crystal, azoxy derivative liquid crystal, pyrimidine derivative liquid crystal, dioxane Examples include derivative liquid crystals and cubane derivative liquid crystals.

  The liquid crystal display device 100 of the present embodiment having the above configuration can perform arbitrary gradation display by modulating light incident from a backlight with a liquid crystal layer whose alignment state is controlled by voltage application. It has become. In addition, since the colored portions 22R, 22G, and 22B are provided for each dot, any color display can be performed by mixing three primary colors (R, G, and B) for each pixel.

In the liquid crystal display device of this embodiment, the gate electrode 80a, the source electrode 34, the drain electrode 35, and the pixel electrode 19 of the TFT 60 are formed by patterning using a liquid phase method.
The source electrode 34 has a structure in which a covering metal film 68a as a covering layer is laminated on a source electrode film 66 as a base layer, while the drain electrode 35 is a covering layer on a drain electrode film 67 as a base layer. By providing a structure in which a certain coated metal film 68a is laminated, the coated metal film 68a allows a metal material such as Ag, Cu, Al constituting the electrode films 66, 67 to diffuse into the insulating film 31c. It can be effectively prevented. The coated metal film 68a can be omitted when diffusion does not matter.
The source electrode 34 and the drain electrode 35 have a structure in which a source electrode film 66 and a drain electrode film 67, which are base layers, are laminated on a barrier metal film 61a. Accordingly, the barrier metal film 61a can favorably prevent Ag, Cu, Al, and the like constituting the electrode films 66 and 67 as the base layer from diffusing into the N ⁺ silicon layer 85 and the amorphous silicon layer 84. In addition, it is possible to prevent the TFT 60 from malfunctioning and performance degradation due to the diffusion.

  Further, in the liquid crystal display device 100, since the TFT 60 and the pixel electrode 19 constituting the dots use conductive members formed by a liquid phase method, the process using an expensive vacuum device is reduced, and the material The use efficiency can be increased, and the cost of the liquid crystal display device can be reduced.

  Further, since the gate electrode 80a has a two-layer structure in which the first electrode layer 81 and the second electrode layer 82 are laminated, the first electrode layer that is the base layer is formed by the second electrode layer 82 that is the covering layer. It is possible to effectively prevent Ag, Cu, and Al constituting 81 from diffusing into the gate insulating film 83. Thereby, it is possible to prevent the TFT 60 from malfunctioning or lowering mobility due to the diffusion.

  In the liquid crystal display device of this embodiment, the mounting terminals 202... May have the same configuration as the source electrode 34 (data line 16) or the gate electrode 80a (scanning line 18a) and be formed in the same layer. . That is, the mounting terminal 202 may be formed simultaneously with the source electrode 34 or the gate electrode 80a. With such a configuration, the mounting terminal 202 has a coating layer made of Ni, Ti, W, or the like on the surface thereof, which is good when soldering an external circuit to the mounting terminal 202. Can be obtained. This is because when the Ag, Cu, Al or the like constituting the base layer is exposed on the surface of the mounting terminal 202 and when the coating layer made of Ni or the like is formed, the latter structure is better. This is because solder can be attached with good wettability.

  In the present embodiment, the gate electrode 80a has a two-layer structure composed of the first electrode layer 81 and the second electrode layer 82. However, the adhesiveness between the first electrode layer 81 and the glass substrate P is good. You may provide the contact | adherence layer for improving. This adhesion layer can be formed of, for example, Mn, and can be formed by a liquid phase method using a liquid material in which Mn fine particles are dispersed.

(Thin Film Transistor Manufacturing Method)
Next, an embodiment of a TFT array substrate manufacturing method including the thin film transistor manufacturing method of the present invention will be described with reference to FIGS. In addition, in each figure, in order to make each layer and each member the size which can be recognized on drawing, the scale is varied for every layer and each member.

[Droplet discharge device]
First, a droplet discharge device used in a plurality of steps of the manufacturing method will be described. In this manufacturing method, ink (liquid material) containing conductive fine particles is ejected in the form of droplets from the nozzles of a droplet ejection head provided in the droplet ejection apparatus to form each conductive member and electrode constituting the thin film transistor. It is supposed to be. As the droplet discharge device used in the present embodiment, the one having the configuration shown in FIG. 5 can be adopted.

FIG. 5A is a perspective view showing a schematic configuration of a droplet discharge device IJ used in the present embodiment.
The droplet discharge device IJ includes a droplet discharge head 301, an X-axis direction drive shaft 304, a Y-axis direction guide shaft 305, a control device CONT, a stage 307, a cleaning mechanism 308, a base 309, and a heater. 315.
The stage 307 supports the substrate P on which ink (liquid material) is provided by the droplet discharge device IJ, and includes a fixing mechanism (not shown) that fixes the substrate P at a reference position.

  The droplet discharge head 301 is a multi-nozzle type droplet discharge head provided with a plurality of discharge nozzles, and the longitudinal direction and the Y-axis direction are made to coincide. The plurality of ejection nozzles are provided on the lower surface of the droplet ejection head 301 in the Y axis direction at regular intervals. From the discharge nozzle of the droplet discharge head 301, the ink containing the conductive fine particles described above is discharged onto the substrate P supported by the stage 307.

An X-axis direction drive motor 302 is connected to the X-axis direction drive shaft 304. The X-axis direction drive motor 302 is a stepping motor or the like, and rotates the X-axis direction drive shaft 304 when a drive signal in the X-axis direction is supplied from the control device CONT. When the X-axis direction drive shaft 304 rotates, the droplet discharge head 301 moves in the X-axis direction.
The Y-axis direction guide shaft 305 is fixed so as not to move with respect to the base 309. The stage 307 includes a Y-axis direction drive motor 303. The Y-axis direction drive motor 303 is a stepping motor or the like, and moves the stage 307 in the Y-axis direction when a drive signal in the Y-axis direction is supplied from the control device CONT.

The control device CONT supplies a droplet discharge control voltage to the droplet discharge head 301. Further, the X-axis direction drive motor 302 has a drive pulse signal for controlling the movement of the droplet discharge head 301 in the X-axis direction, and the Y-axis direction drive motor 303 has a drive pulse signal for controlling the movement of the stage 307 in the Y-axis direction. Supply.
The cleaning mechanism 308 is for cleaning the droplet discharge head 301. The cleaning mechanism 308 includes a Y-axis direction drive motor (not shown). The cleaning mechanism moves along the Y-axis direction guide shaft 305 by driving the Y-axis direction drive motor. The movement of the cleaning mechanism 308 is also controlled by the control device CONT.
Here, the heater 315 is means for heat-treating the substrate P by lamp annealing, and performs evaporation and drying of the solvent contained in the liquid material applied on the substrate P. The heater 315 is also turned on and off by the control device CONT.

  The droplet discharge device IJ discharges droplets onto the substrate P while relatively scanning the droplet discharge head 301 and the stage 307 that supports the substrate P. Here, in the following description, the X-axis direction is a scanning direction, and the Y-axis direction orthogonal to the X-axis direction is a non-scanning direction. Accordingly, the discharge nozzles of the droplet discharge head 301 are provided side by side at regular intervals in the Y-axis direction, which is the non-scanning direction. In FIG. 5A, the droplet discharge head 301 is disposed at a right angle to the traveling direction of the substrate P. However, the angle of the droplet discharging head 301 is adjusted to the traveling direction of the substrate P. You may make it cross. In this way, the pitch between the nozzles can be adjusted by adjusting the angle of the droplet discharge head 301. Further, the distance between the substrate P and the nozzle surface may be arbitrarily adjusted.

FIG. 5B is a schematic configuration diagram of a droplet discharge head for explaining the principle of discharging a liquid material by a piezo method.
In FIG. 5B, a piezo element 322 is installed adjacent to a liquid chamber 321 that stores a liquid material (ink; functional liquid). The liquid material is supplied to the liquid chamber 321 via a liquid material supply system 323 including a material tank that stores the liquid material. The piezo element 322 is connected to a drive circuit 324, and a voltage is applied to the piezo element 322 via the drive circuit 324 to deform the piezo element 322 and elastically deform the liquid chamber 321. And the liquid material is discharged from the nozzle 325 by the change of the internal volume at the time of this elastic deformation. In this case, the amount of distortion of the piezo element 322 can be controlled by changing the value of the applied voltage. In addition, the strain rate of the piezo element 322 can be controlled by changing the frequency of the applied voltage. Since the droplet discharge by the piezo method does not apply heat to the material, it has an advantage of hardly affecting the composition of the material.

[Ink (liquid material)]
Here, an ink (liquid material) suitable for ejection from the droplet ejection head 301 used in the manufacturing method according to the present embodiment will be described.
The conductive member forming ink used in the present embodiment is composed of a dispersion liquid in which conductive fine particles are dispersed in a dispersion medium, or a precursor thereof. Examples of the conductive fine particles include metal fine particles containing, for example, gold, silver, copper, palladium, niobium and nickel, as well as precursors, alloys, oxides thereof, and fine particles such as conductive polymers and indium tin oxide. Used. These conductive fine particles can be used by coating the surface with an organic substance or the like in order to improve dispersibility. The particle diameter of the conductive fine particles is preferably about 1 nm to 0.1 μm. If it is larger than 0.1 μm, there is a possibility that clogging may occur in the nozzles of the liquid discharge head 301 described later, and the denseness of the resulting film may be deteriorated. On the other hand, if it is smaller than 1 nm, the volume ratio of the coating agent to the conductive fine particles becomes large, and the ratio of the organic matter in the obtained film becomes excessive.

  The dispersion medium is not particularly limited as long as it can disperse the conductive fine particles and does not cause aggregation. For example, in addition to water, alcohols such as methanol, ethanol, propanol, butanol, n-heptane, n-octane, decane, dodecane, tetradecane, toluene, xylene, cymene, durene, indene, dipentene, tetrahydronaphthalene, decahydro Hydrocarbon compounds such as naphthalene and cyclohexylbenzene, ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol methyl ethyl ether, 1,2-dimethoxyethane, bis (2- Methoxyethyl) ether, ether compounds such as p-dioxane, propylene carbonate, γ- Butyrolactone, N- methyl-2-pyrrolidone, dimethylformamide, dimethyl sulfoxide, can be exemplified polar compounds such as cyclohexanone. Of these, water, alcohols, hydrocarbon compounds, and ether compounds are preferred from the viewpoints of fine particle dispersibility and dispersion stability, and ease of application to the droplet discharge method (inkjet method). More preferred dispersion media include water and hydrocarbon compounds.

  The surface tension of the conductive fine particle dispersion is preferably in the range of 0.02 N / m to 0.07 N / m. When the liquid is ejected by the ink jet method, if the surface tension is less than 0.02 N / m, the wettability of the ink composition to the nozzle surface increases, and thus flight bending tends to occur, exceeding 0.07 N / m. Since the meniscus shape at the nozzle tip is not stable, it becomes difficult to control the discharge amount and the discharge timing. In order to adjust the surface tension, a small amount of a surface tension regulator such as a fluorine-based, silicone-based, or nonionic-based material may be added to the dispersion within a range that does not significantly reduce the contact angle with the substrate. The nonionic surface tension modifier improves the wettability of the liquid to the substrate, improves the leveling property of the film, and helps prevent the occurrence of fine irregularities in the film. The surface tension modifier may contain an organic compound such as alcohol, ether, ester, or ketone, if necessary.

  The viscosity of the dispersion is preferably 1 mPa · s to 50 mPa · s. When a liquid material is ejected as droplets using the inkjet method, if the viscosity is less than 1 mPa · s, the nozzle periphery is easily contaminated by the outflow of the ink, and if the viscosity is greater than 50 mPa · s, the nozzle hole The clogging frequency in the case becomes high, and not only is it difficult to smoothly discharge droplets, but also the amount of droplets discharged is reduced.

[Method for manufacturing TFT array substrate]
Hereinafter, each manufacturing process of the TFT array substrate will be described with reference to FIGS. 6 to 10 are cross-sectional process diagrams showing a series of processes in the manufacturing method of the present embodiment.
In the manufacturing method of this embodiment, a bank is formed on a glass substrate, and a thin film transistor is manufactured by forming an electrode pattern and a wiring pattern by a droplet discharge method using a droplet discharge device in a region surrounded by the bank. And a method of manufacturing a TFT array substrate.

<Gate electrode formation process>
First, as shown in each drawing of FIG. 6, a glass substrate P serving as a base is prepared, a bank 30 is formed on one surface thereof, and then predetermined ink is dropped onto an opening 30 a provided in the bank 30. Thus, the gate electrode 80a is formed in the opening 30a. This gate electrode forming step includes a bank forming step, a liquid repellent treatment step, a first electrode layer forming step, a second electrode layer forming step, and a firing step.

{Bank formation process}
First, in order to form the gate electrode 80a (and the scanning line 18a) in a predetermined pattern on the glass substrate, as shown in FIG. 6A, a bank 30 having openings 30a of the predetermined pattern on the glass substrate P is formed. Form. The bank 30 is a partition member that partitions the substrate surface in a plane, and any method such as a photolithography method or a printing method can be used to form the bank. For example, when using the photolithography method, an organic system such as an acrylic resin according to the height of the bank formed on the glass substrate P by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, etc. A photosensitive material is applied to form a photosensitive material layer. And the bank 30 provided with the opening part 30a for gate electrodes is formed by irradiating an ultraviolet-ray with respect to the photosensitive material layer according to the bank shape to form. The bank 30 may be an inorganic structure formed using a liquid material containing polysilazane.

{Liquid repellency treatment process}
Next, the bank 30 is subjected to a liquid repellency treatment to impart liquid repellency to the surface thereof. As the lyophobic treatment, for example, a plasma treatment method (CF ₄ plasma treatment method) using tetrafluoromethane as a treatment gas in an air atmosphere can be employed. The conditions of the CF ₄ plasma treatment are, for example, a plasma power of 50 kW to 1000 kW, a tetrafluoromethane gas flow rate of 50 ml / min to 100 ml / min, a substrate transfer speed to the plasma discharge electrode of 0.5 mm / sec to 1020 mm / sec, and a substrate temperature. Is 70 ° C to 90 ° C. The processing gas is not limited to tetrafluoromethane (carbon tetrafluoride), and other fluorocarbon gases can also be used.
By performing such a liquid repellency treatment, the bank 30 is introduced with a fluorine group in the resin constituting the bank 30 and imparted with high liquid repellency.

Prior to the liquid repellency treatment, an ashing treatment using O ₂ plasma or a UV (ultraviolet) irradiation treatment is performed for the purpose of cleaning the surface of the glass substrate P exposed on the bottom surface of the opening 30a. It is preferable. By performing this treatment, the residue of the bank on the surface of the glass substrate P can be removed, and the difference between the contact angle of the bank 30 after the lyophobic treatment and the contact angle of the substrate surface can be increased. In this step, the droplets arranged in the opening 30a can be accurately confined inside the opening 30a. Further, when the bank 30 is made of an acrylic resin or a polyimide resin, if the bank 30 is exposed to O ₂ plasma prior to the CF ₄ plasma treatment, it is more likely to be fluorinated (liquid repellent). Therefore, when the bank 30 is formed of these resin materials, it is preferable to perform the O ₂ ashing process prior to the CF ₄ plasma process.

Specifically, the O ₂ ashing process is performed by irradiating the substrate P with oxygen in a plasma state from a plasma discharge electrode. As the processing conditions, for example, the plasma power is 50 W to 1000 W, the oxygen gas flow rate is 50 ml / min to 100 ml / min, the plate conveyance speed of the substrate P with respect to the plasma discharge electrode is 0.510 mm / sec to 10 mm / sec, and the substrate temperature is 70. ° C to 90 ° C.

Note that the lyophobic treatment (CF ₄ plasma treatment) on the bank 30 has some influence on the surface of the substrate P made lyophilic by the residue treatment previously performed, but particularly when the substrate P is made of glass or the like. Since the introduction of fluorine groups due to the lyophobic treatment hardly occurs, the lyophilicity, that is, the wettability of the substrate P is not substantially impaired. Further, the bank 30 may be formed of a material having liquid repellency (for example, a resin material having a fluorine group), so that the liquid repellency treatment may be omitted.

{First electrode layer forming step}
Next, as shown in FIG. 6B, the first electrode layer forming ink 81a is dropped from the droplet discharge head 301 of the droplet discharge device IJ into the opening 30a. Here, an ink 81a using Ag (silver) as the conductive fine particles and diethylene glycol diethyl ale as the solvent (dispersion medium) is discharged and arranged. At this time, the liquid repellent property is imparted to the surface of the bank 30 and the lyophilic property is imparted to the substrate surface at the bottom of the opening 30a. Even if it is mounted on the surface, it is slid into the opening 30a by being repelled on the bank surface.

  Next, after discharging droplets made of electrode forming ink, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. In this embodiment, for example, heating is performed at 180 ° C. for about 60 minutes. This heating is not necessarily performed in the air, such as in a nitrogen gas atmosphere.

  This drying process can also be performed by lamp annealing. The light source used for lamp annealing is not particularly limited, but excimer lasers such as infrared lamps, xenon lamps, YAG lasers, argon lasers, carbon dioxide lasers, XeF, XeCl, XeBr, KrF, KrCl, ArF, ArCl, etc. It can be used as a light source. In general, these light sources have an output in the range of 10 W to 5000 W, but in the present embodiment, a range of 100 W to 1000 W is sufficient. By performing this intermediate drying step, a solid first electrode layer 81 is formed as shown in FIG.

{Second electrode layer forming step}
Next, as shown in FIG. 6C, the second electrode layer forming ink 82 a is disposed in the opening 30 a of the bank 30 by using a droplet discharge method using a droplet discharge device. Here, ink (liquid material) using Ni (nickel) as the conductive fine particles and water and diethanolamine as the solvent (dispersion medium) is discharged and arranged. At this time, the liquid repellent property is imparted to the surface of the bank 30 and the lyophilic property is imparted to the substrate surface at the bottom of the opening 30a. Even if it is mounted on the surface, it is slid into the opening 30a by being repelled on the bank surface. However, the surface of the first electrode layer 81 formed first inside the opening 30a does not necessarily have a high affinity for the ink 82a dropped in this step. Prior to dripping, an intermediate layer for improving the wettability of the ink 82 a may be formed on the first electrode layer 81. The intermediate layer is appropriately selected according to the type of the dispersion medium constituting the ink 82a. However, when the ink 82a uses an aqueous dispersion medium as in the present embodiment, for example, an intermediate layer made of titanium oxide is used. If a layer is formed, very good wettability can be obtained on the surface of the intermediate layer.

  After discharging the droplets, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. The processing conditions are, for example, a heating temperature of 180 ° C. and a heating time of about 60 minutes. This heating is not necessarily performed in the air, such as in a nitrogen gas atmosphere.

  This drying process can also be performed by lamp annealing. As a light source of light used for lamp annealing, those mentioned in the intermediate drying step after the first electrode layer forming step can be used. Similarly, the output during heating can be in the range of 100W to 1000W. By performing this intermediate drying step, a solid second electrode layer 82 is formed on the first electrode layer 81 as shown in FIG.

{Baking process}
The dried film after the discharging step needs to completely remove the dispersion medium in order to improve the electrical contact between the fine particles. In addition, when a coating agent such as an organic substance is coated on the surface of the conductive fine particles in order to improve the dispersibility in the liquid, it is also necessary to remove this coating agent. For this reason, the substrate after the discharge process is subjected to heat treatment and / or light treatment.

This heat treatment and / or light treatment is usually carried out in the atmosphere, but can also be carried out in an inert gas atmosphere such as nitrogen, argon or helium, if necessary. The treatment temperature of the heat treatment and / or the light treatment depends on the boiling point (vapor pressure) of the dispersion medium, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of the fine particles, the presence and amount of the coating agent, Although it is determined appropriately in consideration of the heat-resistant temperature, etc., even in such a configuration, the first electrode layer and the second electrode layer are formed using the materials mentioned above, so that the firing temperature is 250 ° C. or lower. be able to. However, in this step, since the semiconductor layer is not provided on the substrate P, the firing temperature can be increased within the range of the heat resistance temperature of the bank 30, for example, a firing temperature of 250 ° C. or higher or about 300 ° C. A metal wiring having even better conductivity can be formed.
Through the above steps, the dry film after the discharge process ensures electrical contact between the fine particles, is converted into a conductive film, and the first electrode layer 81 and the second electrode layer 82 are stacked in the opening 30a of the bank 30. Thus formed gate electrode 80a is formed. Further, as shown in FIG. 3, the scanning line 18a integrated with the gate electrode 80a is also formed on the glass substrate P by the above process.

  Moreover, it is preferable that the film thickness of the 1st electrode layer 81 after a baking process shall be about 500 nm-1500 nm, and the film thickness of the 2nd electrode layer 82 shall be about 20 nm-400 nm. If the thickness of the second electrode layer 82 is less than 20 nm, the diffusion of the metal element from the first electrode layer 81 to the gate insulating film 83 cannot be sufficiently prevented, and if the thickness exceeds 400 nm, the gate electrode 80a ( And the resistance of the scanning line 18a) increases, which is not preferable.

  In each of the above steps, the first electrode layer 81 made of Ag and the second conductive layer 82 made of Ni are formed, and the gate electrode 80a is formed by a laminate of the first electrode layer 81 and the second electrode layer 82. Although formed, the first electrode layer 81 may be a metal other than Ag, for example, Cu or Al, or an alloy containing these metals as a main component. The second metal layer 82 may be Ti, W, Mn other than Ni, or an alloy containing these metals as a main component.

<Gate insulation film formation process>
Next, a gate insulating film 83 made of silicon nitride is formed on the gate electrode 80a. The gate insulating film 83 can be formed, for example, by depositing the entire surface by a plasma CVD method and then appropriately patterning by a photolithography method. As the source gas used in the CVD process, a mixed gas of monosilane and dinitrogen monoxide, TEOS (tetraethoxysilane, Si (OC ₂ H ₅ ) ₄ ) and oxygen, disilane and ammonia, etc. are suitable, and the gate to be formed The film thickness of the insulating film 83 is about 150 nm to 400 nm.

<Semiconductor layer formation process>
Next, the semiconductor layer 33 shown in FIG. 7A is formed on the gate insulating film 83. The semiconductor layer 33 is formed by applying an amorphous silicon film having a thickness of about 150 nm to 250 nm and an N ⁺ silicon film having a thickness of about 50 nm to 100 nm on the entire surface of the substrate P on which the gate insulating film 83 is formed by a plasma CVD method or the like. It is obtained by laminating and patterning into a predetermined shape by photolithography. Disilane or monosilane is suitable as the source gas used in the amorphous silicon film forming step. In the subsequent N ⁺ silicon film forming step, film formation can be performed by introducing a source gas for forming the N ⁺ silicon layer into the film forming apparatus used for forming the amorphous silicon film.

Thereafter, the amorphous silicon film and the N ⁺ silicon film are patterned into the shape shown in FIG. 7A by photolithography, so that an amorphous silicon layer 84 and an N ⁺ silicon layer having a predetermined planar shape are formed on the gate insulating film 83. Thus, the semiconductor layer 33 in which 85 is stacked is obtained. At the time of patterning, a substantially concave resist similar to the side sectional shape of the semiconductor layer 33 shown in the figure is selectively placed on the surface of the N ⁺ silicon film, and etching is performed using the resist as a mask. By such a patterning method, the N ⁺ silicon layer 85 is selectively removed in a region overlapping with the gate electrode 80a and divided into two regions, and these N ⁺ silicon layers 85 and 85 are respectively connected to source contacts. Regions and drain contact regions are formed.

<Electrode formation process>
Next, the source electrode 34 and the drain electrode 35 shown in FIG. 4 are formed on the glass substrate P on which the semiconductor layer 33 is formed. This electrode forming process includes a bank forming process, a liquid repellency process, a barrier metal film forming process, an electrode film forming process, a covering metal film forming process, and a firing process.

{Bank formation process}
When the amorphous silicon layer 84 and the N ⁺ silicon layer 85 are formed, a bank for forming the source electrode and the drain electrode is formed on the glass substrate P. The bank can be formed by an arbitrary method such as a photolithography method or a printing method. For example, when photolithography is used, organic photosensitivity mainly composed of acrylic resin or the like according to the height of the bank to be formed by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, etc. The material is applied to form a photosensitive material layer, and then the photosensitive material layer is irradiated with ultraviolet rays in accordance with the bank shape.

Here, two types of banks, that is, the first bank portion 31b and the second bank portion 31a are formed. First, as shown in FIG. 7B, the first bank portion 31b has an amorphous silicon layer. 84 and N ⁺ silicon layer, and exposure by ultraviolet irradiation is performed so as to be positioned at a substantially central portion of the amorphous silicon layer 84. That is, the first bank portion 31b is formed as a partition member that partitions the source electrode and the drain electrode formed in a subsequent process in a plane. On the other hand, as shown in FIG. 7C, the second bank portion 31 a is formed in a region outside the amorphous silicon layer 84 so as to surround the amorphous silicon layer 84.

  The bank portions 31a and 31b may be inorganic structures formed using a liquid material containing polysilazane. When forming a bank of inorganic material, the heating temperature at the time of curing is often higher than when forming a bank using an organic material such as a resin material, but the curing temperature is 250 for the liquid material containing polysilazane. It may be below ℃. Since the curing temperature is 250 ° C. or lower in this way, hydrogen desorption does not occur in the existing semiconductor layer 33 on the substrate P, and the ON resistance of the thin film transistor and carrier mobility due to this hydrogen desorption are not increased. The reduction can be prevented.

In addition, in order to remove the resist (organic substance) residue at the time of bank formation between each bank part 31a and 31b, it is preferable to perform a residue process. As this residue treatment, a UV irradiation treatment for performing a residue treatment by irradiating ultraviolet rays, an O ₂ ashing treatment using oxygen as a processing gas in an air atmosphere, or the like can be selected. Here, an O ₂ ashing treatment is performed. The condition of the ashing process may be the same as the condition used when patterning the bank 30 previously.

{Liquid repellency treatment process}
Subsequently, the bank portions 31a and 31b are subjected to a liquid repellency treatment to impart liquid repellency to the surfaces thereof. As the lyophobic treatment, for example, a plasma treatment method (CF ₄ plasma treatment method) using tetrafluoromethane as a treatment gas in an air atmosphere can be employed. The CF ₄ plasma processing conditions may be the same as the plasma processing conditions for the bank 30 as long as the bank portions 31 a and 31 b are made of the same material as the previous bank 30. By performing such a liquid repellency treatment, a fluorine group is introduced into the resin constituting the bank portions 31a and 31b, and high liquid repellency is imparted.

  Although the surface of the gate insulating film 83 made lyophilic by the previously performed residue processing is somewhat affected by the lyophobic treatment for the bank portions 31a and 31b, the gate insulating film 83 is subjected to the lyophobic processing. Since the introduction of the fluorine group hardly occurs, the lyophilicity (wetting property) is not impaired. Moreover, when each bank part 31a, 31b is formed with the material (for example, resin material which has a fluorine group) which has liquid repellency, a liquid repellency process can be abbreviate | omitted.

{Barrier metal film formation process}
Next, as shown in FIG. 7C, the ink (liquid material) 61 for forming the barrier metal film 61a shown in FIG. It is applied to a region surrounded by the part 31b and the second bank part 31a. Here, ink is discharged using Ni as the conductive fine particles and water and diethanolamine as the solvent (dispersion medium).

  In this barrier metal film forming step, the ink 61 for forming the barrier metal film is ejected as droplets from the droplet ejection head 301 of the droplet ejection apparatus IJ and is surrounded by the first bank portion 31b and the second bank portion 31a. Placed in the designated area. At this time, since the liquid repellent properties are imparted to the bank portions 31a and 31b, even if a part of the ejected droplets is placed on the bank portions, the bank surface is liquid repellent. As shown in FIG. 7C, the ink (droplet) 61 bounced and dripped on the surface of the bank part flows down to a region surrounded by the first bank part 31b and the second bank part 31a.

Next, after a droplet of barrier metal film forming ink is discharged and disposed, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. In this embodiment, for example, 180 ° C. heating is performed for about 60 minutes. This heating is not necessarily performed in the air, such as in an N ₂ atmosphere.

This drying process can also be performed by lamp annealing. As a light source of light used for lamp annealing, those mentioned in the intermediate drying step after the first electrode layer forming step can be used. Similarly, the output during heating can be in the range of 100W to 1000W. By performing this intermediate drying step, desired barrier metal films 61a and 61a are formed across the gate insulating film 83 and the N ⁺ silicon layer 85 as shown in FIG. 8A. The barrier metal films 61a and 61a form part of the source electrode and the drain electrode, respectively.

{Electrode film forming process}
Next, as shown in FIG. 8B, the electrode film forming ink 65 is applied onto the barrier metal film 61a by using a droplet discharge method by the droplet discharge device IJ. Here, ink is ejected using silver as the conductive fine particles and diethylene glycol diethyl ether as the solvent (dispersion medium).

  In this electrode film process, the electrode film forming ink 65 is discharged as droplets from the droplet discharge head, and the droplets are regions surrounded by the first bank portion 31b and the second bank portion 31a on the substrate P. To place. At this time, since the liquid repellent properties are imparted to the bank portions 31a and 31b, even if some of the ejected droplets are placed on the bank portions 31a and 31b, the bank surface is liquid repellent. As a result, the liquid material that is repelled and dripped on the surfaces of the bank portions 31a and 31b flows down to the region.

  Prior to this electrode film forming step, an intermediate layer for improving the wettability of the ink 65 may be formed on the surface of the barrier metal film 61a formed in advance. As this intermediate layer, for example, Mn or the like can be used, and in forming the film, a droplet discharge method similar to that for the electrode films 66 and 67 can be used.

After discharging the droplets, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. In this embodiment, for example, 180 ° C. heating is performed for about 60 minutes. This heating is not necessarily performed in the air, such as in an N ₂ atmosphere.

  This drying process can also be performed by lamp annealing. As a light source of light used for lamp annealing, those mentioned in the intermediate drying step after the first electrode layer forming step can be used. Similarly, the output during heating can be in the range of 100W to 1000W. By performing this intermediate drying step, as shown in FIG. 8C, a source electrode film 66 and a drain electrode film 67 are formed on the barrier metal films 61a and 61a, respectively.

{Coating metal film forming process}
Next, as shown in FIG. 9A, the first ink (liquid material) 68 for forming the covering metal film 68a shown in FIG. 4 is used by using the droplet discharge method by the droplet discharge device IJ. It is applied to a region (upper surfaces of the source electrode film 66 and the drain electrode film 67) surrounded by the bank part 31b and the second bank part 31a. Here, ink is discharged using Ni as the conductive fine particles and water and diethanolamine as the solvent (dispersion medium).

  In this covering metal film forming step, the ink 68 for forming the covering metal film is discharged as droplets from the droplet discharge head 301 of the droplet discharge device IJ and is surrounded by the first bank portion 31b and the second bank portion 31a. Placed in the selected area. At this time, since the liquid repellent properties are imparted to the bank portions 31a and 31b, even if a part of the ejected droplets is placed on the bank portions, the bank surface is liquid repellent. The ink (droplet) 68 bounced and dripped on the surface of the bank part flows down to the region.

  Prior to this coating metal film forming step, an intermediate layer for improving the wettability of the ink 68 may be formed on the surfaces of the electrode films 66 and 67 previously formed. As this intermediate layer, for example, a thin film containing titanium oxide can be used, and in forming the film, a droplet discharge method similar to that for the coated metal film 68a can be used.

Next, after discharging droplets made of electrode forming ink, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. In this embodiment, for example, 180 ° C. heating is performed for about 60 minutes. This heating is not necessarily performed in the air, such as in an N ₂ atmosphere.

  This drying process can also be performed by lamp annealing. As a light source of light used for lamp annealing, those mentioned in the intermediate drying step after the first electrode layer forming step can be used. Similarly, the output during heating can be in the range of 100W to 1000W. By performing this intermediate drying step, the covering metal films 68a and 68a are formed on the source electrode film 66 and the drain electrode film 67 as shown in FIG. 9B. These covering metal films 68a and 68a form part of the source electrode and the drain electrode, respectively.

{Baking process}
The dried film after the discharging process needs to completely remove the dispersion medium in order to improve the electrical contact between the fine particles. Further, when a coating agent such as an organic substance is coated on the surface of the conductive fine particles in order to improve dispersibility, it is also necessary to remove this coating agent. For this reason, the substrate after the discharge process is subjected to heat treatment and / or light treatment.

The heat treatment and / or light treatment is usually performed in the air, but may be performed in an inert gas atmosphere such as nitrogen, argon, helium, etc., if necessary. The treatment temperature of the heat treatment and / or the light treatment depends on the boiling point (vapor pressure) of the dispersion medium, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of the fine particles, the presence and amount of the coating agent, It is determined appropriately in consideration of the heat resistant temperature.
In the present embodiment, since the metal material constituting the stacked structure of the source electrode 34 and the drain electrode 35 is the above-described metal material, the heat treatment in this firing step can be performed at 250 ° C. or less. ing. That is, an electrode member having good conductivity can be formed even by heating at 250 ° C. or lower. Thereby, it is possible to satisfactorily prevent an increase in ON resistance and a decrease in carrier mobility due to hydrogen desorption in the semiconductor layer 33, and to maintain the operational reliability of the formed thin film transistor. It has become.

  Through the above steps, the dry film after the discharge process is converted into a conductive film while ensuring electrical contact between the fine particles. Then, a source electrode 34 and a drain electrode 35 having a three-layer structure are formed on the glass substrate P. As shown in FIG. 4, the data line 16 integrated with the source electrode 34 is also formed on the substrate P by the above process.

  The thickness of the barrier metal film 61a and the coated metal film 68a after the firing step is preferably about 20 nm to 400 nm, and the thickness of the electrode films 66 and 67 is preferably about 500 nm to 1500 nm. When the thickness of the barrier metal film 61a is less than 20 nm, the diffusion of the metal element from the electrode films 66 and 67 to the semiconductor layer 33 cannot be sufficiently prevented, and when the thickness exceeds 400 nm, the source electrode 34 (and data). Since the resistance of the line 16) and the drain electrode 35 increases, it is not preferable. Further, when the thickness of the covering metal film 68a is less than 20 nm, the diffusion of the metal element from the electrode films 66 and 67 to the bank 31c (see FIG. 4) and the liquid crystal layer cannot be sufficiently prevented, and the film exceeds 400 nm. The thickness is not preferable because the resistance of the source electrode 34 (and the data line 16) and the drain electrode 35 increases.

  In each of the above steps, the electrode films 66 and 67 made of Ag are formed as the base layer, the barrier metal film 61a made of Ni is formed as the barrier layer, and the coated metal film 68a made of Ni is formed as the coating layer. However, the material constituting these metal films is not limited to Ag and Ni, and the electrode films 66 and 67 may be, for example, Cu, Al, or an alloy containing these metals as a main component. Further, the barrier metal film 61a and the covering metal film 68a may be Ti, W, Mn, or an alloy containing these metals as a main component.

<Bank removal process>
Next, of the banks provided on the glass substrate P, the first bank part 31b and the second bank part 31a are selectively removed. In this removal step, the bank portions 31a and 31b are removed by an ashing process such as plasma ashing or ozone ashing. Plasma ashing is a method in which a gas such as oxygen gas converted into plasma reacts with a bank, and the bank is vaporized and removed. Ozone ashing is a method in which ozone (O ₃ ) is decomposed into active oxygen, and the active oxygen and the bank are reacted to vaporize and remove the bank. Through this bank removal step, a thin film transistor (TFT) 60 formed on the glass substrate P can be obtained as shown in FIG.

<Pixel electrode formation process>
Next, the pixel electrode 19 shown in FIG. 4 is formed on the glass substrate P on which the TFT 60 is formed. This pixel electrode forming step includes a bank forming step, a liquid repellent treatment step, a liquid material arranging step, and a firing step.

{Bank formation process}
Next, as shown in FIG. 10A, a bank for forming the pixel electrode 19 at a predetermined position on the substrate P is formed. The bank 31c is formed so as to partially cover the TFT 60 as shown in FIG. 10, and is formed in a substantially lattice shape surrounding each pixel electrode 19 shown in FIG. The bank can be formed by an arbitrary method such as a photolithography method or a printing method. For example, when photolithography is used, organic photosensitivity mainly composed of acrylic resin or the like according to the height of the bank to be formed by a predetermined method such as spin coating, spray coating, roll coating, die coating, dip coating, etc. The material is applied to form a photosensitive material layer, and then the photosensitive material layer is irradiated with ultraviolet rays in accordance with the bank shape.
Here, among the constituent members of the TFT 60, the bank 31c is patterned so that the drain electrode 35 protrudes into a region surrounded by the bank 31c. In the patterning of the bank 31c, the coating metal film 68a is formed on the surface portion of the existing drain electrode 35 on the substrate P. Therefore, the etching solution enters the electrode films 66 and 67 and erodes them. Can be prevented.

  The bank 31c may be an inorganic structure formed using a liquid material containing polysilazane. When forming a bank of an inorganic material, the heating temperature at the time of curing is often higher than when forming a bank using an organic material such as a resin material. However, the curing temperature of the bank 31c can be increased by using the above material. Can be set to 250 ° C. or lower. Thereby, hydrogen desorption in the semiconductor layer 33 can be effectively prevented, and an increase in ON resistance and a decrease in carrier mobility of the thin film transistor formed can be prevented.

In order to remove a resist (organic matter) residue at the time of bank formation in a region surrounded by the bank 31c, it is preferable to perform a residue treatment. As this residue treatment, a UV irradiation treatment for performing a residue treatment by irradiating ultraviolet rays, an O ₂ ashing treatment using oxygen as a processing gas in an air atmosphere, or the like can be selected. Here, an O ₂ ashing treatment is performed. The condition of the ashing process may be the same as the condition used when patterning the bank 30 previously.

{Liquid repellency treatment process}
Subsequently, a liquid repellency treatment is performed on the bank 31c to impart liquid repellency to the surface. As the lyophobic treatment, the same treatment method as that described above can be used.
Although the surface of the gate insulating film 83 made lyophilic by the residue treatment performed previously is somewhat affected by the lyophobic treatment for the bank 31c, introduction of fluorine groups into the gate insulating film 83 by the lyophobic treatment is performed. Is unlikely to occur, so its lyophilicity (wetting) is not impaired. Further, when the bank 31c is formed of a liquid repellent material (for example, a resin material having a fluorine group), the liquid repellent treatment can be omitted.

{Liquid material arrangement forming process}
Next, as shown in FIG. 10B, ink (liquid material) for forming a pixel electrode is applied to a region surrounded by the bank 31c by using a droplet discharge method by the droplet discharge device IJ. . Here, ink in which fine particles of a light-transmitting conductive material such as ITO, IZO, FTO, etc. are dispersed in a solvent (dispersion medium) is ejected. In this embodiment, particularly, a light-transmitting property is good even at a baking temperature of 250 ° C. or less. And a liquid material for forming a translucent conductive film that can obtain electrical conductivity. Examples of such a liquid material include a liquid material containing ITO fine particles and a silicon organic compound, and a liquid material containing ITO fine particles, an indium organic compound and a tin organic compound. By using these liquid materials, it is possible to form a translucent conductive film having a structure in which ITO fine particles are firmly bonded to each other by a matrix of SiO ₂ or ITO generated from the metal organic compound, and the firing temperature is low. Even so, it is possible to form a light-transmitting conductive film in which ITO fine particles are densely arranged and good conductivity can be obtained between the fine particles.

  In this pixel electrode forming step, ink 69 containing a pixel electrode forming material is discharged as droplets from the droplet discharge head 301 of the droplet discharge device IJ and is disposed in a region surrounded by the bank 31c. At this time, since the bank 31c has liquid repellency, even if a part of the ejected droplets is placed on the bank portion, the bank surface has liquid repellency, so Then, the dropped ink (droplet) 69 flows down to the region 31d surrounded by the bank 31c as shown in FIG.

Next, after discharging droplets made of electrode forming ink, a drying process is performed as necessary to remove the dispersion medium. The drying process can be performed, for example, by a heating process using a normal hot plate or an electric furnace that heats the substrate P. In this embodiment, for example, 180 ° C. heating is performed for about 60 minutes. This heating is not necessarily performed in the air, such as in an N ₂ atmosphere.

  This drying process can also be performed by lamp annealing. As a light source of light used for lamp annealing, those mentioned in the intermediate drying step after the first electrode layer forming step can be used. Similarly, the output during heating can be in the range of 100W to 1000W. By performing this intermediate drying step, a desired pixel electrode 19 is formed as shown in FIG.

{Baking process}
The dried film after the discharging process needs to completely remove the dispersion medium in order to improve the electrical contact between the fine particles. Further, when a coating agent such as an organic substance is coated on the surface of the conductive fine particles in order to improve dispersibility, it is also necessary to remove this coating agent. For this reason, the substrate after the discharge process is subjected to heat treatment and / or light treatment.

The heat treatment and / or light treatment is usually performed in the air, but may be performed in an inert gas atmosphere such as nitrogen, argon, helium, etc., if necessary. The treatment temperature of the heat treatment and / or the light treatment depends on the boiling point (vapor pressure) of the dispersion medium, the type and pressure of the atmospheric gas, the thermal behavior such as the dispersibility and oxidation of the fine particles, the presence and amount of the coating agent, It is determined appropriately in consideration of the heat resistant temperature.
In the present embodiment, since the liquid material for forming the pixel electrode 19 is the liquid material having the above-described configuration, the heat treatment in this baking step can be performed at 250 ° C. or less. Thereby, it is possible to satisfactorily prevent an increase in ON resistance and a decrease in carrier mobility due to hydrogen desorption in the semiconductor layer 33, and to maintain the operational reliability of the formed thin film transistor. It has become.

  As a result of the above steps, the dry film after the discharge process ensures electrical contact between the fine particles and is converted into a conductive film. As a result, the pixel electrode 19 is formed on the substrate P, and the thin film transistor shown in FIG. 4 is provided. The TFT array substrate thus manufactured can be manufactured.

  And according to the manufacturing method of this embodiment, since the heating temperature in the heat treatment after the semiconductor layer 33 is formed on the glass substrate P is set to 250 ° C. or less, hydrogen desorption in the semiconductor layer 33 is effective. Can be prevented. Thereby, an increase in ON resistance and a decrease in carrier mobility can be prevented, and a TFT 60 excellent in operation reliability and a highly reliable TFT array substrate can be obtained.

  In the above embodiment, when the source electrode 34 and the drain electrode 35 are formed, the barrier metal film 61a, the electrode films 66 and 67, and the covering metal film 68 are fired at the same time. The firing may be performed sequentially. That is, after firing the barrier metal film 61a, ink for forming the electrode films 66 and 67 is ejected and arranged to form the electrode film, and after firing the electrode films 66 and 67, the coated metal film 61 is formed. It is also possible to employ a method of discharging and arranging ink for this purpose. In this case, the stability of the existing metal film on the substrate P with respect to the solvent (dispersion medium) is improved.

  In the first embodiment and the second embodiment, a droplet discharge method using a droplet discharge device is used to dispose droplets (liquid material). As another method, for example, FIG. A Cap coating method as shown in FIG. 11 can also be employed. The Cap coating method is a film forming method using a capillary phenomenon, and when a slit 71 is inserted into the coating liquid 70 and the coating liquid level is raised in this state, a liquid deposit 72 is generated at the upper end of the slit 71. The coating liquid 70 can be applied to the surface of the substrate P by bringing the substrate P into contact with the liquid deposit 72 and translating the substrate P in a predetermined direction.

  Furthermore, the thin film transistor manufacturing method described in each embodiment can be applied to various electro-optical device manufacturing methods including the thin film transistor. For example, it is preferably employed when forming a thin film transistor such as a liquid crystal device, an organic electroluminescence display device, or a plasma display device.

(Electronics)
FIG. 12 is a perspective view showing an example of an electronic apparatus according to the present invention. A cellular phone 1300 shown in this figure includes the liquid crystal display device of the present invention as a small-sized display portion 1301 and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304.
The electro-optical device according to each of the embodiments is not limited to the mobile phone, but is an electronic book, a personal computer, a digital still camera, a video monitor, a viewfinder type or a monitor direct-view type video tape recorder, a car navigation device, a pager, and an electronic device. It can be suitably used as an image display means for devices such as notebooks, calculators, word processors, workstations, videophones, POS terminals, and touch panels. Such an electronic device is inexpensive and excellent in reliability.

1 is an equivalent circuit diagram of a liquid crystal display device according to an embodiment. The top view which shows the whole structure same as the above. FIG. 2 is a plan configuration diagram showing one pixel region. The partial cross section block diagram of a TFT array board | substrate same as the above. (A) is a figure which shows an example of a droplet discharge apparatus, (b) is the schematic of an ejection head. Sectional process drawing for demonstrating the manufacturing method of a thin-film transistor. Sectional process drawing for demonstrating the manufacturing method of a thin-film transistor. Sectional process drawing for demonstrating the manufacturing method of a thin-film transistor. Sectional process drawing for demonstrating the manufacturing method of a thin-film transistor. Sectional process drawing for demonstrating the manufacturing method of a thin-film transistor. The schematic sectional drawing for demonstrating Cap coat method. FIG. 11 is a perspective configuration diagram illustrating an example of an electronic device.

Explanation of symbols

P ... glass substrate (substrate), 80a ... gate electrode (conductive member), 81 ... first electrode layer (base layer), 82 ... second electrode layer (covering layer), 83 ... gate insulating film, 84 ... semiconductor layer, 85 ... N ⁺ silicon layer, 30, 31c ... bank, 31b ... first bank portion, 31a ... second bank portion, 34 ... source electrode (conductive member), 35 ... drain electrode (conductive member), 60 ... TFT (thin film transistor) ), 61a ... barrier metal film (barrier layer), 66 ... source electrode film (base layer), 67 ... drain electrode film (base layer), 68a ... coated metal film (cover layer)

Claims (4)

A scanning line; a data line; a thin film transistor provided at an intersection of the scanning line and the data line; and a mounting terminal connected to an external circuit. The thin film transistor includes a semiconductor layer and an electrode film. A method of manufacturing an electro-optical device having:
Forming the semiconductor layer on the substrate;
Forming a bank surrounding a first region corresponding to the electrode member and surrounding a second region corresponding to the mounting terminal;
Applying a liquid material to the first region and the second region;
Drying the liquid material, forming the electrode film in the first region, and forming the mounting terminal in the second region;
Forming an intermediate layer containing titanium oxide on the electrode film;
Applying one or more metal materials selected from Ni, Ti, W, and Mn to the first region and the second region, and forming a coated metal film on the intermediate layer;
A method of manufacturing an electro-optical device having The bank has a first bank portion provided in a region which overlaps with the semiconductor layer, the method of manufacturing an electro-optical device according to claim 1, further comprising a second bank portion surrounding the semiconductor layer. The electrode film is a source electrode or a gate electrode of the thin film transistor,
The electrode film, method of manufacturing the electro-optical device according to claim 1 or claim 2 is formed simultaneously with the mounting terminal. The electrode film is the scanning line or the data line,
The electrode film, method of manufacturing the electro-optical device according to claim 1 or claim 2 is formed simultaneously with the mounting terminal.

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