JP3724787B2 - Electrode substrate, method for producing the same, and liquid crystal display device including the electrode substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrode substrate, a manufacturing method thereof, and a liquid crystal display device including the electrode substrate. More specifically, an electrode substrate on which a transparent conductive film is formed in contact with both an inorganic insulating film region made of an inorganic insulating film and an organic insulating film region made of an organic insulating film, a manufacturing method thereof, and a liquid crystal display device including the electrode substrate About.
[0002]
[Prior art]
A transparent conductive film containing ITO (indium tin oxide) can be used as an electrode that transmits light and controls light. An electrode substrate using a transparent conductive film having such characteristics has been put into practical use not only for display devices such as electroluminescence display devices but also for touch panels, solar cells and the like.
[0003]
A liquid crystal display device is given as a display device using an electrode substrate in which a transparent conductive film is formed on both an organic insulating film and an inorganic insulating film. Liquid crystal display devices have been actively researched as one of flat panel displays to replace CRTs. Taking advantage of their low power consumption and thinness, battery-driven ultra-compact TVs and notebook-type displays have been developed. It has already been put into practical use as a display device for personal computers. Here, a liquid crystal display device will be described as a specific example of a display device using an electrode substrate in which a transparent conductive film is formed on both an organic insulating film and an inorganic insulating film.
[0004]
FIG. 1 schematically shows a basic configuration of the liquid crystal display device 100. The liquid crystal display device 100 is an active matrix TFT array type using thin film transistors (hereinafter referred to as TFTs) as switching elements, which is advantageous when high display quality is desired.
[0005]
As shown in FIG. 1, the liquid crystal display device 100 includes a liquid crystal layer (not shown) provided between an upper substrate 102 and a lower substrate (electrode substrate) 101, and the liquid crystal layer is on the upper substrate 102. It is controlled by the upper electrode 104 and the plurality of pixel electrodes 103 on the lower substrate 101. In the lower substrate 101, each of the plurality of pixel electrodes 103 is connected to the source wiring 105 through the switching element (TFT) 108, and the gate of the TFT 108 is connected to the gate wiring 106.
[0006]
FIG. 2 is a top view of the lower substrate 101 (electrode substrate) of the liquid crystal display device. Here, a transmissive active matrix liquid crystal display device is assumed as the liquid crystal display device. However, the liquid crystal display device is not limited to the transmissive type, and the transmissive region of the transmissive / reflective liquid crystal display device can be considered similarly.
[0007]
The electrode substrate 101 refers to the insulating substrate 20 and the entire components formed thereon. The electrode substrate 101 is divided into two areas, a display area 150 and a peripheral area 160. In FIG. 2, the display area 150 is indicated by diagonal lines. In the display region 150, a plurality of pixel electrodes 103 and a plurality of TFTs 108 for controlling the plurality of pixel electrodes 103 are provided. The pixel electrode 103 is formed of a transparent conductive film. When the electrode substrate 101 is used in a transmissive liquid crystal display device, at least a part of the insulating substrate 20 is formed of a transparent material, and display is performed using light (generally a light source) from the opposite side of the display side. Light is transmitted and controlled by forming the electrode with a transparent conductive film.
[0008]
On the other hand, the peripheral region 160 is provided with a plurality of gate connection terminal portions 110, a plurality of source connection terminal portions 120, and a plurality of common connection terminal portions 130. A gate line 105, a source line 106, and a common line 107 corresponding to each gate connection terminal part 110, source connection terminal part 120, and common connection terminal part 130 are formed from the peripheral area 160 to the display area 150. In this specification, the gate connection terminal portion 110, the source connection terminal portion 120, and the common connection terminal portion 130 are collectively referred to as peripheral terminal portions.
[0009]
FIG. 3 shows an enlarged top view of the display area 150 of the electrode substrate 101. In FIG. 3, a region surrounded by a broken line corresponds to one pixel electrode 103. Each gate wiring 105 and each common wiring 107 are provided in parallel, and a plurality of source wirings 106 are provided so as to be orthogonal to each gate wiring 105 and each common wiring 107, respectively. As shown in FIG. 3, at each intersection of each gate wiring 105 and each source wiring 106, each gate wiring 105 and source wiring 106 are at least connected to the gate electrode or source electrode of the TFT 108 which is a switching element. Is so branched. A connection electrode 48 connected to the drain electrode of the TFT 108 is provided so as to partially overlap the common wiring 107, and a contact hole 50 is provided in a part of a region where the connection electrode 48 and the common wiring 107 overlap.
[0010]
FIG. 4 is a cross-sectional view of the display region 150 of the electrode substrate 101 taken along the line AA ′ of FIG. In FIG. 4, the TFT 108 is shown on the left side (A side), and the contact hole 50 is shown on the right side (A ′ side). Here, the A side in FIG. 4 is referred to as a TFT portion, and the A ′ side is referred to as a contact hole portion.
[0011]
In the TFT portion, a branch portion of the gate wiring 105 is formed on the insulating substrate 20, and a gate insulating film 44 is provided so as to cover them. Silicon nitride (SiN _x ) may be used as the gate insulating film 44. An amorphous semiconductor layer 45 is formed on the gate insulating film 44, a source electrode 46 a is formed above the left side of the amorphous semiconductor layer 45, and a drain electrode 46 b is formed above the right side of the amorphous semiconductor layer 45. The source electrode 46 a is connected to the source wiring 106, and the drain electrode 46 b is connected to the connection electrode 48. The TFT 108 thus formed is covered with an organic insulating film 49 made of a transparent material, and the planarized organic insulating film 49 is covered with a pixel electrode 103 made of a transparent conductive film.
[0012]
In the contact portion, the common wiring 107 is formed on the insulating substrate 20, and the gate insulating film 44 is provided so as to cover them. The gate insulating film 44 is covered with a connection electrode 48. In the contact hole portion, an organic insulating film 49 is formed on the connection electrode 48, and the organic insulating film 49 is covered with the pixel electrode 103. However, a contact hole 50 for directly connecting the connection electrode 48 and the pixel electrode 103 is provided.
[0013]
By forming the display region 150 of the electrode substrate 101 as described above, a high aperture ratio can be obtained mainly by two advantages. The first reason is that since the pixel electrode 103 is formed on the organic insulating film 49 whose surface is flattened, the orientation of liquid crystal molecules (not shown) in the liquid crystal layer caused by the stepped portion of the pixel electrode 103 is formed. This is because display defects (domain phenomenon) due to disturbance can be eliminated and the effective display area in the liquid crystal layer can be increased. The second reason is that a relatively thick organic insulating film 49 having a thickness of 0.3 μm to 2 μm is formed, and a pixel electrode 103 is formed thereon, whereby a gate wiring on the substrate side of the organic insulating film 103 is formed. This is because no electrical short circuit occurs between the source line 106 and the pixel electrode 103 on the upper surface side (display side). Therefore, the pixel electrode 103 can be formed in a wide area so as to overlap with the wiring such as the gate wiring 105 and the source wiring 106 when viewed from the viewing side.
[0014]
On the other hand, since the peripheral terminal portion lacks reliability at the time of rework that causes a connection failure with the mounting member, a transparent conductive film is generally formed on the inorganic insulating film to be an electrode. The formation of the transparent conductive film prevents the electrode at the peripheral terminal portion from being oxidized, and as a result, the electrode from increasing in resistance. Although it is conceivable to form the electrode material of the peripheral terminal portion on the organic insulating film, it is not preferable from the viewpoint of reliability to form the transparent conductive film on the organic insulating film.
[0015]
Etching after forming the transparent conductive film is generally wet etching. This is because when dry etching is performed, the organic insulating film is altered and the insulation becomes brittle. In addition, when the electrode substrate is applied to a liquid crystal display device, the liquid crystal layer is contaminated due to dry etching, which may cause deterioration in display quality. Therefore, in this specification, unless otherwise specified, “etching” means wet etching.
[0016]
As described above, when the transparent conductive film formed on both the organic insulating film and the inorganic insulating film is etched, it can be considered that etching can be performed at the same time. In this specification, the etching shift means the length of a film removed by etching. Further, an etching shift per unit time is defined as an “etching rate”. When the transparent conductive film on the organic insulating film and the transparent conductive film on the inorganic insulating film are designed with substantially the same size and the same etching is performed, the etching shift is different, Deviation occurs in size. That is, the etching rate is different. Therefore, when the transparent conductive film is etched, as shown in FIG. 5, a difference occurs between the design dimension and the finished dimension of one transparent conductive film. Therefore, the transparent conductive film on the organic insulating film and the transparent conductive film on the inorganic insulating film cannot be etched at the same time.
[0017]
Here, a method for manufacturing the electrode substrate of the liquid crystal display device illustrated in FIG. 2 will be described with reference to FIGS. FIG. 6 shows a method of forming the pixel electrode 103 of the TFT portion, the gate connection terminal portion 110 / common connection terminal portion 130, and the source connection terminal portion 120 (see FIG. 2) by steps (a) to (g). Although FIG. 6 shows a process for forming the pixel electrode 103 in the TFT portion, the process for forming the pixel electrode 103 is not particularly limited to the TFT portion, and the pixel electrode 103 in the display region 150 is formed in the same manner. it is conceivable that.
[0018]
In the step (a), a transparent conductive film 155 (for example, ITO) is simultaneously formed on the TFT portion and the peripheral terminal portion of the peripheral region 160 (see FIG. 2).
[0019]
The transparent conductive film 155 to be the pixel electrode 103 of the TFT portion is formed on the organic insulating film 49 formed flat.
[0020]
In the gate / common connection terminal portions 110 and 130, the inorganic insulating film 144 is formed in a state in which the gate wiring 105 or the common wiring 107 is formed on the insulating substrate 20 and the central portion on the gate wiring 105 or the common wiring 107 is removed. Is formed. An electrode 154 is provided in the central portion on the gate wiring 105 or the common wiring 107. On the electrode 154, a transparent conductive film 155 is formed as a transparent electrode 157 having a stable connection resistance.
[0021]
In the source connection terminal portion 120, an inorganic insulating film 144 is formed so as to cover the insulating substrate 20, a source wiring 106 is provided on the inorganic insulating film 144, and a transparent conductive film serving as the transparent electrode 157 is formed so as to cover them. 155 is deposited.
[0022]
In the step (b), the peripheral terminal portion is subjected to photoresist patterning. In the peripheral terminal portion, a first resist 165 is formed on a portion where the transparent conductive film 155 is left (that is, a portion where the transparent electrode 157 is formed). As the first resist 165, for example, a positive resist made of Tokyo Ohka Novolak resin is used. In the step (b), a first resist 165 is formed on the entire surface of the transparent conductive film 155 in the TFT portion.
[0023]
In step (c), wet etching is performed to remove unnecessary transparent conductive film 155 in the peripheral terminal portion.
[0024]
In the step (d), the first resist 165 is removed. At this time, the transparent electrode 157 made of the transparent conductive film 155 is formed in the peripheral terminal portion, while the transparent conductive film 155 in the TFT portion remains formed on the entire surface.
[0025]
In step (e), the pixel electrode 103 is subjected to photoresist patterning. A second resist 167 is formed on a portion where the transparent conductive film 155 is left (that is, a portion to be the pixel electrode 103). As the second resist 167, for example, a positive type resist made of Tokyo Ohka Novolak resin is used. In the step (e), a second resist 167 is formed on the entire peripheral terminal portion.
[0026]
In step (f), wet etching is performed to remove unnecessary transparent conductive film 155 in the TFT portion.
[0027]
In the step (g), the pixel electrode 103 is formed by removing the second resist 167.
[0028]
Thus, although the electrode substrate 101 is formed, as described above, the etching of the transparent conductive film 155 on the inorganic insulating film 144 (FIG. 6C) and the transparent conductive film 155 on the organic insulating film 49 are performed. Etching (f of FIG. 6) has to be performed separately because the etching rate is different.
[0029]
The present invention has been made in view of such a current situation, and an object of the present invention is to simultaneously and accurately etch a transparent conductive film formed on an organic insulating film and a transparent conductive film formed on an inorganic insulating film. It is possible to provide an electrode substrate and a manufacturing method thereof, and a liquid crystal display device including such an electrode substrate.
[0030]
The present invention performs plasma processing to overcome the above-described problems.
[0031]
Here, the following is mentioned as a conventional example using plasma treatment for the electrode substrate of the liquid crystal display device.
[0032]
In Japanese Patent Laid-Open No. 9-152625, in order to improve the adhesion between the organic insulating film and the transparent conductive film, after forming the organic insulating film, oxygen plasma treatment is performed, and then the transparent conductive film is formed. A manufacturing method is disclosed.
[0033]
JP-A-11-283934 discloses a resin surface in order to improve electrical connection between the upper pixel electrode and the lower drain electrode through the contact hole of the organic insulating film in terms of display quality. A method of plasma processing with a gas such as CF ₄ + O ₂ is disclosed. However, when the plasma treatment is performed on the organic insulating film using a mixed gas of CF ₄ + O ₂ , the etching rate of the transparent conductive film on the organic insulating film increases. Therefore, the transparent conductive film on the organic insulating film and the transparent conductive film on the inorganic insulating film cannot be etched simultaneously.
[0034]
[Means for Solving the Problems]
In the electrode substrate having the organic insulating film region made of an organic insulating film and the inorganic insulating film region made of an inorganic insulating film on the same surface, the electrode substrate of the present invention is subjected to plasma treatment on the organic insulating film region. Performing a step, forming a transparent conductive film in contact with the organic insulating film region and the inorganic insulating film region, and simultaneously etching the transparent conductive film in contact with the organic insulating film region and the inorganic insulating film region; .
[0035]
The step of performing plasma treatment on the organic insulating film region may include a step of simultaneously performing plasma processing on the inorganic insulating film region.
[0036]
The plasma treatment may be any selected from the group of oxygen plasma treatment, Ar plasma treatment, and CF ₄ plasma treatment.
[0037]
The plasma treatment may include a step of performing an Ar plasma treatment after the oxygen plasma treatment.
[0038]
The plasma treatment may include a step of performing a CF ₄ plasma treatment after the oxygen plasma treatment.
[0039]
In the plasma treatment, the mean square of the surface roughness on the organic insulating film may be 1.0 nm or less.
[0040]
You may further include the process of heat-processing a transparent conductive film after the said etching process.
[0041]
You may perform the said heat processing at 150 to 220 degreeC.
[0042]
An electrode substrate according to the present invention includes an organic insulating film region made of an organic insulating film having a mean square roughness of 1.0 nm or less, and an inorganic insulating film made of an inorganic insulating film provided on the same side as the organic insulating film A region, and a transparent conductive film in contact with the organic insulating film region and the inorganic insulating film region.
[0043]
The square average of the surface roughness of the organic insulating film may be 0.28 nm or more and 1.0 nm or less.
[0044]
The crystal grain size of the transparent conductive film on the organic insulating film may be 20 nm or more and 50 nm or less.
[0045]
The transparent conductive film on the organic insulating film may have a crystal grain size of 20 nm to 40 nm.
[0046]
The liquid crystal display device of the present invention includes the electrode substrate described above.
[0047]
DETAILED DESCRIPTION OF THE INVENTION
In order to solve the above problems, the inventors of the present application, namely, an etching rate of a transparent conductive film in contact with an inorganic insulating film region made of an inorganic insulating film and a transparent conductive film in contact with an organic insulating film region made of an organic insulating film. It has been found that plasma treatment may be performed under appropriate conditions before forming the transparent conductive film in order to achieve the same level.
[0048]
The organic insulating film region referred to here is, for example, a region where the organic insulating film 49 shown in FIG. 11 or the organic insulating film 1449 shown in FIG. 18 shows a region where an inorganic insulating film is not formed in the plastic substrate 1420 shown in FIG. The inorganic insulating film region refers to a region where the inorganic insulating film 144 shown in FIG. 11 or the inorganic insulating film shown in FIG. 17 or 18 is formed as a layer or film in contact with the transparent conductive film.
[0049]
FIG. 7 is a graph showing the relationship between the wet etching time (minutes) and the etching shift (μm) when the entire electrode substrate is subjected to plasma treatment before forming the transparent conductive film. Here, CF ₄ , oxygen, and Ar are used as plasma processing gases. Moreover, ITO is used as a transparent conductive film. In the graph of FIG. 7, the results of CF ₄ plasma treatment, oxygen plasma treatment, and Ar plasma treatment are indicated by ◆, ■, and ▲, and their linear interpolations are indicated by bold lines, broken lines, and dotted lines, respectively. In the graph of FIG. 7, the result of the etching shift of the transparent conductive film on the inorganic insulating film is indicated by ●, and the linear interpolation is indicated by a thin line. Note that the etching shift of the transparent conductive film on the inorganic insulating film is not significantly different whether or not the surface of the inorganic insulating film is plasma-treated.
[0050]
When the wet etching time is 3 minutes, the etching shift of the transparent conductive film on the organic insulating film is 1.0 μm or less regardless of whether the plasma processing gas is CF ₄ , oxygen, or Ar. The difference from the etching shift (about 0.5 μm) of the transparent conductive film is small. Accordingly, the gas used may be any of CF ₄ , oxygen, and Ar.
[0051]
When wet etching time is long to some extent (for example, 5 minutes), if oxygen is used as the plasma processing gas, the increase in etching shift is large (about 3.2 μm), so that the etching shift of the transparent conductive film on the inorganic insulating film is The difference increases and etching cannot be performed at the same time. When the plasma processing gas is CF ₄ or Ar, even if the wet etching time is 5 minutes, the increase in etching shift is not so large, so that etching can be performed simultaneously.
[0052]
Further, it can be seen from the graph of FIG. 7 that the change of the etching shift of the transparent conductive film on the inorganic insulating film with respect to the wet etching time is not so large as compared with the case of the organic insulating film. In general, the change in the etching shift of the transparent conductive film on the inorganic insulating film is smaller than the change in the etching shift of the transparent conductive film on the organic insulating film, and the transparent conductive film on the inorganic insulating film is within the range of the experimental conditions of the present application. The etching shift is 1.0 μm or less.
[0053]
FIG. 8 is a graph showing the relationship between the plasma processing time and the etching shift of the transparent conductive film on the organic insulating film. The results of CF ₄ , Ar, and oxygen as gases used for the plasma treatment are indicated by ◆, ■, and ▲, respectively. Regardless of which gas is used, the etching shift increases as the plasma processing time increases. However, in the case of oxygen plasma processing, the increase in etching shift with respect to the increase in plasma processing time is remarkably large, whereas in the case of CF ₄ plasma processing or Ar plasma processing, the increase in etching shift with respect to the increase in plasma processing time is not so much. not big. When the plasma treatment is about 30 seconds, the etching shift is 1.0 μm or less regardless of the gas of CF ₄ , Ar, or oxygen, and the difference from the etching shift of the transparent conductive film on the inorganic insulating film is small. Etching can be performed simultaneously with the transparent conductive film on the inorganic insulating film. However, when the plasma treatment time becomes long, the transparent conductive film on the organic insulating film subjected to the oxygen plasma treatment cannot be etched simultaneously with the transparent conductive film on the inorganic insulating film.
[0054]
FIG. 9 is a graph showing the relationship between the root mean square (RMS) of the surface roughness (nm) of the surface of the organic insulating film formed by the plasma treatment and the etching shift (μm). In the graph of FIG. 9, O ₂ -180 indicates that oxygen plasma treatment was performed for 180 seconds, and Ar-30 indicates that Ar plasma treatment was performed for 30 seconds. The wet etching time was 180 seconds. The surface roughness was measured with a SPA500 manufactured by Seiko Instruments Inc. At this time, the measurement was performed in a tapping mode (DFM), and the strength of the cantilever was set at 20 N / M.
[0055]
As can be seen from the graph of FIG. 9, the etching shift tends to increase as the RMS of the surface roughness increases regardless of the type of plasma processing gas. When the RMS of the surface roughness is 1.0 nm or less, the etching shift can be suppressed to 1.0 μm or less. As a result, it is possible to approach the etching shift of the transparent conductive film on the inorganic insulating film when the wet etching time is 180 seconds, and the transparent conductive film on the organic insulating film and the transparent conductive film on the inorganic insulating film are simultaneously etched. be able to.
[0056]
In addition, it is confirmed that the electrical connection between the transparent conductive film 103 and the connection electrode 48 is good by performing Ar plasma treatment for 30 seconds. The RMS of the surface roughness under the conditions is 0.28 nm.
[0057]
Further, after the transparent conductive film is formed, the etching shift is further reduced by performing heat treatment (for example, a temperature of 150 ° C. or higher and 220 ° C. or lower, more preferably 200 ° C. or higher and 220 ° C. or lower). For example, when a heat treatment is further performed after forming a transparent conductive film on an organic insulating film that has been subjected to Ar plasma treatment, the etching shift is reduced by about 0.15 μm compared to the case where heat treatment is not performed. Further, when a heat treatment is further performed after forming a transparent conductive film on the organic insulating film that has been subjected to the CF ₄ plasma treatment, the etching shift is reduced by about 0.05 μm as compared with the case where the heat treatment is not performed.
[0058]
As shown in FIGS. 7 and 8, since the etching shift increases as the wet etching time and the plasma processing time increase, heat treatment is performed on the transparent conductive film on the plasma-processed organic insulating film so that the etching shift is reduced. It is preferable to do.
[0059]
As an application example of the electrode substrate according to the present invention, a liquid crystal display device will be described in comparison with a liquid crystal display device to which a conventional electrode substrate is applied. However, the liquid crystal display device is merely an example, and the present invention can be applied to any form as long as it is an electrode substrate in which a transparent conductive film is formed on both an organic insulating film and an inorganic insulating film. For example, in an electroluminescence element, a transparent conductive film is formed as an anode on a substrate made of an organic insulator in a light emitting region, while a transparent conductive film is formed on an inorganic insulator in a terminal region. The present invention can be applied.
[0060]
Steps (I) to (IV) in FIG. 10 involve plasma treatment and transparency in the peripheral terminal portions (gate / common connection terminal portion, source connection terminal portion) of the display region 150 (see FIG. 1) and the peripheral region 160 according to the present invention. The formation process of an electrically conductive film is shown. These steps correspond to the steps before forming the transparent conductive film 155 in step (a) of FIG.
[0061]
Further, the display region 150 shows both the TFT portion (A side) and the contact hole portion (A ′ side) as in FIG.
[0062]
In step (I) of FIG. 10, an organic insulating film 49 is formed so as to cover the TFT 108 in the display region, and a part of the organic insulating film 50 is removed in order to form the contact hole 50 in the contact hole portion.
[0063]
In the gate / common connection terminal portions 110 and 130, the gate wiring 105 or the common wiring 107 is formed on the insulating substrate 20, and the inorganic insulating film 144 and the electrode 154 are formed so as to cover them.
[0064]
In the source connection terminal portion 120, the inorganic insulating film 144 is formed on the insulating substrate 20, and the source wiring 106 is formed thereon.
[0065]
As the organic insulating film 49 formed in the display region 150, for example, a photosensitive resin is used. The organic insulating film 49 is applied by a spin coating method, exposed in a photolithography process, and then developed with an alkaline solution. Thereby, a part of the organic insulating film 49 is removed so that the connection electrode 48 is exposed, and a contact hole 50 is formed. Subsequently, the organic insulating film 49 is heat treated at 200 ° C. for curing.
[0066]
In step (II), oxygen plasma treatment is performed on the display region 150, the gate / common connection terminal portions 110 and 130, and the source connection terminal portion 120. The oxygen plasma treatment is performed, for example, at 9000 sccm and 3000 mTorr for 30 seconds.
[0067]
In step (III), CF ₄ plasma treatment or Ar plasma treatment is performed on the display region 150, the gate / common connection terminal portions 110 and 130, and the source connection terminal portion 120.
[0068]
The CF ₄ plasma treatment is performed, for example, in Power 1000W for 30 seconds in an atmosphere of CF ₄ gas of 400 sccm and 70 mTorr. The Ar plasma treatment is performed for 30 seconds at an RF power of 1.0 kW in an atmosphere of Ar gas of 290 sccm and 1.7 Pa.
[0069]
In step (IV), a transparent conductive film 155 to be the pixel electrode 103 or the transparent electrode 157 later is formed on the display region 150, the gate / common connection terminal portions 110 and 130, and the source connection terminal portion 120. For example, when an acrylic resin is used as the organic insulating film 49, the transparent conductive film 155 is formed at 200 ° C. in consideration of thermal embrittlement of the acrylic resin. Even if another material is used for the organic insulating film 49, it is preferable to form the film at the same temperature. The film formation of the transparent conductive film is performed at a thickness of 800 to 1200 mm using, for example, a single wafer type sputtering apparatus. As an example of the film forming conditions at this time, a mixed gas of O ₂ and Ar is used as a sputtering gas, In ₂ O ₃ (containing 5% to 10% of SnO ₂ ) is used as a target, a gas flow rate is 100 sccm, and a gas pressure is 0. .7 Pa and power are set to 1.3 kW.
[0070]
In the step shown in FIG. 10, the oxygen plasma treatment (step (II)) is followed by the CF ₄ plasma treatment or Ar plasma treatment (step (III)). After step (II) in FIG. 10, step (IV) may be performed without performing step (III). Alternatively, CF ₄ plasma treatment or Ar plasma treatment is performed without oxygen plasma treatment, that is, after step (I) in FIG. 10, step (III) and step (IV) are continued without performing step (II). Also good.
[0071]
However, the contact resistance of the contact hole 50 can be reduced by performing the oxygen plasma treatment (step (II)). This is because the oxygen plasma treatment effectively removes the residue remaining in the contact hole, the material remaining after the etching treatment, and the like.
[0072]
By performing the plasma treatment as described above, the pixel electrode 103 and the transparent electrode 157 are formed on the organic insulating film 49 and the inorganic insulating film 144, respectively, as shown in steps (a) to (d) of FIG. The FIG. 11 showing a method for manufacturing an electrode substrate according to the present invention corresponds to FIG. 6 for explaining a conventional method for forming an electrode substrate.
[0073]
Specifically, in step (a) of FIG. 11, a transparent conductive film 155 is formed on the organic insulating film 49 in the display region 150 and on the inorganic insulating film 144 in the peripheral region 160.
[0074]
In the step (b), photoresist patterning of the pixel electrode and the peripheral terminal portion is performed. In the peripheral terminal portion, a resist 169 is formed on a portion where the transparent conductive film 155 is left (that is, a portion where the pixel electrode 103 or the transparent electrode 157 is formed). As the resist 169, for example, a positive type resist made of Tokyo Ohka Novolak resin is used.
[0075]
In step (c), wet etching is performed to remove unnecessary transparent conductive film 155 in the pixel electrode and the peripheral terminal portion. The wet etching is performed for 180 seconds using, for example, ferric chloride at 40 ° C. as a wet etching solution. As the etching solution, a mixed solution of FeCl ₃ and HCl having a liquid temperature of 40 ° C. is used.
[0076]
In step (d), the resist 169 is removed. At this time, the transparent electrode 157 made of the transparent conductive film 155 is formed in the peripheral terminal portion, and the pixel electrode 103 is formed in the display region 150.
[0077]
That is, according to the present invention, the steps (b) to (d) and (e) to (g) shown in FIG. 6 can be performed simultaneously. Therefore, the manufacturing process is shortened, and as a result, the manufacturing cost can be reduced and the production capacity of the manufacturing site can be improved. Further, since the number of photoresist patterning steps is reduced, it is possible to avoid a decrease in yield due to pattern defects, and the amount of resist and stripping solution used is reduced. Further, since the number of times the organic insulating film is exposed to the stripping solution is reduced, the swelling of the organic insulating film can be reduced, and as a result, the quality reliability of the panel is improved.
[0078]
Further, the electrode 154 and the transparent conductive film 155 (later transparent electrode 157) are formed by forming the electrode 154 in the gate / common connection terminal portions 110 and 130 and performing the plasma treatment to form the transparent conductive film 155. The contact resistance with is reduced.
[0079]
FIG. 12 is a graph showing the relationship between the CF ₄ plasma processing time and the contact resistance between the electrode 154 and the transparent conductive film 155 (later transparent electrode 157) in the gate / common connection terminal portions 110 and 130. From FIG. 12, it can be seen that by performing the CF ₄ plasma treatment for 30 seconds or more, the contact resistance is reduced by about 3 digits, and a stable contact resistance can be obtained. In addition to this, not only CF ₄ plasma treatment but also oxygen plasma treatment or Ar plasma treatment can provide the same effect.
[0080]
Further, by performing the above-described heat treatment after forming the transparent conductive film 155 to be the transparent electrode 157, the crystallinity of the transparent conductive film 155 is improved, and the resistance of the transparent electrode 157 on the inorganic insulating film 144 is reduced. As a result, the wiring resistance on the inorganic insulating film 144 is also reduced.
[0081]
FIG. 13 shows the annealing temperature (° C.) of the heat treatment after forming the transparent conductive film, and the resistance per unit area (sheet resistance) of the transparent electrode 157 made of the transparent conductive film 155 on the inorganic insulating film 144 (Ω / □) shows changes. From FIG. 13, it is understood that the sheet resistance is reduced by performing the heat treatment.
[0082]
When CF ₄ plasma treatment or Ar plasma treatment is performed as in the present embodiment, component analysis is performed by an analyzer such as XPS (X-ray photoelectron spectrometer), which is mixed into the surface layer of the organic insulating film. The gas used for the plasma treatment can be detected.
[0083]
By controlling the crystal grain size of the transparent conductive film, the etching rate of the transparent conductive film on the organic insulating film can be made closer to the etching rate of the transparent conductive film on the inorganic insulating film.
[0084]
FIG. 14 is a graph showing the relationship between the time (minutes) for wet etching the transparent conductive film and the etching shift (μm). In the graph of FIG. 14, the result when the crystal grain size of the transparent conductive film on the organic insulating film is about 40 nm is shown by ●, and the linear interpolation is shown by a bold line. Further, the result of the transparent conductive film on the inorganic insulating film is shown by ■, and the linear interpolation is shown by a thin line. Here, acrylic resin was used as the organic insulating film, ITO was used as the transparent conductive film, and SiN _x was used as the inorganic insulating film. As shown in the graph of FIG. 14, when the etching time is 3 to 5 minutes, the etching shift of the transparent conductive film on the organic insulating film is less than 1.5 μm, and the etching shift of the transparent conductive film on the inorganic insulating film is Is smaller than 1.0 μm. Accordingly, since the difference between the etching shift of the transparent conductive film on the organic insulating film and the etching shift of the transparent conductive film on the inorganic insulating film is relatively small, the transparent conductive film on the organic insulating film and the inorganic insulating film can be obtained in a predetermined etching time. It is possible to simultaneously etch the transparent conductive film on the film.
[0085]
The graph of FIG. 14 shows the case where the crystal grain size of the transparent conductive film on the organic insulating film is about 40 nm, but if the crystal grain size is in the range of 20 nm to 50 nm, similarly, Since the difference in etching shift between the transparent conductive film and the transparent conductive film on the inorganic insulating film is small, both can be etched at the same time.
[0086]
For comparison, FIG. 15 is a graph showing the relationship between the etching time (μm) and the time (minutes) for wet etching of the transparent conductive film when the crystal grain size of the transparent conductive film on the organic insulating film is about 100 nm. Show. As shown in FIG. 15, the etching shift of the transparent conductive film on the organic insulating film is 2.0 μm or more when the etching time is 3 minutes to 5 minutes. Is larger than the etching shift of the transparent conductive film on the inorganic insulating film, and the difference is also large. Therefore, it is difficult to etch both at the same time.
[0087]
By performing plasma treatment before forming the transparent conductive film, the crystal grain size can be controlled. When the oxygen plasma treatment or the CF ₄ plasma treatment is performed for a long time before forming the transparent conductive film, the surface of the organic insulating film is rough, and thus the crystal grain size tends to increase. Further, when Ar plasma treatment is performed before forming the transparent conductive film, the roughness of the surface of the organic insulating film is relaxed, so that the crystal grain size tends to be small.
[0088]
FIG. 16 is a graph showing the relationship between the wet etching time of the transparent conductive film on the organic insulating film and the etching shift. An acrylic resin was used as the organic insulating film, ITO was used as the transparent conductive film, and the wet etching time was 3.0 minutes. As shown in FIG. 16, when the crystal grain size of the transparent conductive film on the organic insulating film is 20 nm or more and 50 nm or less, the etching shift is 1.0 μm or less, and the etching shift of the transparent conductive film on the inorganic insulating film is Since the difference from about 0.2 μm (see FIG. 14) is small, simultaneous etching can be performed within a predetermined etching time. Moreover, when the crystal grain size of the transparent conductive film on the organic insulating film is 20 nm or more and 50 nm or less, it has a suitable electrical resistance to function as an electrode. If the crystal grain size of the transparent conductive film on the organic insulating film is 20 nm or more and 40 nm or less, the etching shift is further small, so that the controllability of the transparent conductive film on the organic insulating film is improved. In addition, when the crystal grain size of the surface of the transparent conductive film on the organic insulating film is 60 nm or more, the inventors greatly increase the etching shift as shown in FIG. It has been confirmed that simultaneous etching patterning cannot be performed because the etching rate of the transparent conductive film on the insulating film is greatly different.
[0089]
On the other hand, when the crystal grain size of the transparent conductive film on the organic insulating film is smaller than 20 nm, the transparent conductive film has a too small grain size, resulting in an increase in electrical resistance, resulting in no effective functioning as an electrode. In addition, when an electrode substrate having a large resistance of the transparent conductive film is applied to a liquid crystal display device, the electrical resistance of the pixel electrode in the display region and the gate connection terminal portion, the common connection terminal portion, and the source connection terminal portion in the peripheral region Will increase. In particular, an increase in electrical resistance of the gate connection terminal portion, common connection terminal portion, and source connection terminal portion in the peripheral region is not desirable when manufacturing a high-definition / large-sized liquid crystal display device.
[0090]
The outline of the present invention will be schematically described with reference to steps (a) to (e) of FIG.
[0091]
In step (a), an inorganic insulating film 1444 is formed over the insulating substrate 1420. As the insulating substrate 1420, a plastic substrate can be used in addition to transparent glass. Polyimide, polyethylene terephthalate, polyacrylate, polyethylene or the like is used as a material for the plastic substrate. As the inorganic insulating film 1444, for example, SiO ₂ , SiN _x, or TaO ₂ is used and formed to a thickness of 500 to 5000 mm.
[0092]
In step (b), an organic insulating film 1449 is formed in another region on the insulating substrate 1420. As the organic insulating film 1449, for example, an epoxy resin, an acrylic resin, polycarbonate, or the like is used, and is formed with a thickness of 100 mm to 1 mm.
[0093]
Thereafter, plasma treatment is performed. Ar, CF ₄ , and oxygen can be used as the plasma treatment gas.
[0094]
In the step (c), a transparent conductive film 1455 is formed by sputtering or the like so as to cover the insulating substrate 1420, the inorganic insulating film 1444, and the organic insulating film 1449. ITO may be used as the transparent conductive film 1455. The transparent conductive film 1455 is formed with a thickness of 500 to 3000 mm.
[0095]
In the step (d), after patterning the photoresist 1465, wet etching is performed to pattern the transparent conductive film 1455. As the photoresist 1465, a novolac resin may be used, and a mixed solution of FeCl ₃ and HCl or HBr may be used as an etchant for wet etching.
[0096]
In step (e), a transparent conductive film 1455 having a desired shape is formed over the inorganic insulating film 1444 and the organic insulating film 1449, and the electrode substrate 1700 is completed. At this time, the difference in etching shift between the transparent conductive film 1455 on the inorganic insulating film 1444 and the transparent conductive film 1455 on the organic insulating film 1449 is desirably 2 μm or less, but is not limited thereto.
[0097]
The method for forming the inorganic insulating film 1444 and the organic insulating film 1449 is appropriately selected depending on the material. Specific methods include letterpress printing, screen printing, and spin coater. Further, after film formation, heat treatment or ultraviolet irradiation may be further performed.
[0098]
As a result of a peel test, it was found that the adhesion between the transparent conductive film 1455 and the inorganic insulating film 1444 thus formed and the adhesion between the transparent conductive film 1455 and the organic insulating film 1449 are good.
[0099]
In the above description, the electrode substrate 1700 in which the inorganic insulating film 1444 and the organic insulating film 1449 are formed over the insulating substrate 1420 is shown. However, the present invention is not limited to this, and as shown in FIG. 18, a plastic substrate is used as the insulating substrate 1420, an inorganic insulating film 1444 is formed in a part of the region, and the inorganic insulating film 1444 is formed. In addition, an electrode substrate 1800 in which a transparent conductive film 1455 is formed on part of the plastic substrate 1420 is also included in the range. Such an electrode substrate 1800 incorporates an integrated circuit including a switching element on the inorganic insulating film 1444, and the transparent conductive film 1455 can be used not only as an electrode to be controlled but also as a wiring.
[0100]
【The invention's effect】
According to the present invention, plasma treatment (for example, Ar plasma treatment, CF ₄ plasma treatment, oxygen plasma treatment) is performed under appropriate conditions before forming the transparent conductive film, so as to be in contact with the organic insulating film region. The transparent conductive film formed and the transparent conductive film formed so as to be in contact with the inorganic insulating film region can be simultaneously etched, and the process can be shortened. Thereby, the manufacturing cost of an electrode and a liquid crystal display device can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a configuration of a liquid crystal display device.
FIG. 2 is a top view of an electrode substrate.
FIG. 3 is an enlarged view of a display region of the electrode substrate of FIG.
4 is a cross-sectional view taken along the line AA ′ in FIG. 3;
FIG. 5 is a diagram showing a difference between a design dimension and a finishing dimension.
FIG. 6 is a diagram illustrating a conventional method for manufacturing an electrode substrate.
FIG. 7 is a graph showing the relationship between wet etching time and etching shift.
FIG. 8 is a graph showing the relationship between plasma processing time and etching shift.
FIG. 9 is a graph showing the relationship between the surface roughness on the organic insulating film and the etching shift.
FIG. 10 is a diagram for explaining a plasma treatment before forming a transparent conductive film.
FIG. 11 is a diagram illustrating a method for manufacturing an electrode substrate according to the present invention.
FIG. 12 is a graph showing the relationship between CF ₄ plasma treatment time and contact resistance.
FIG. 13 is a graph showing the relationship between annealing temperature and sheet resistance.
14 is a graph showing the relationship between etching time and etching shift when the crystal grain size of the transparent conductive film on the organic insulating film is about 40 nm. FIG. 15 is a graph showing crystal grains of the transparent conductive film on the organic insulating film. It is a graph which shows the relationship between the etching time in case a diameter is about 100 nm, and an etching shift.
FIG. 16 is a graph showing the relationship between the crystal grain size of the transparent conductive film on the organic insulating film and the etching shift.
FIG. 17 is a diagram for explaining the outline of the production of the electrode substrate of the present invention.
FIG. 18 is a view showing an electrode substrate according to another embodiment of the present invention.

Claims (11)

A method for producing an electrode substrate, comprising:
In the electrode substrate having an organic insulating film region made of an organic insulating film and an inorganic insulating film region made of an inorganic insulating film on the same surface side, a step of performing plasma treatment on the organic insulating film region;
Forming a transparent conductive film in contact with the organic insulating film region and the inorganic insulating film region;
Simultaneously etching the transparent conductive film in contact with the organic insulating film region and the inorganic insulating film region;
A method for producing an electrode substrate including:   The method for manufacturing an electrode substrate according to claim 1, wherein the step of performing plasma treatment on the organic insulating film region includes the step of simultaneously performing plasma treatment on the inorganic insulating film region. 2. The electrode substrate manufacturing method according to claim 1, wherein the plasma treatment is one selected from the group consisting of oxygen plasma treatment, Ar plasma treatment, and CF ₄ plasma treatment.   The method for manufacturing an electrode substrate according to claim 1, wherein the plasma treatment includes a step of performing Ar plasma treatment after oxygen plasma treatment. The electrode substrate manufacturing method according to claim 1, wherein the plasma treatment includes a step of performing CF ₄ plasma treatment after oxygen plasma treatment.   2. The electrode substrate manufacturing method according to claim 1, wherein the plasma treatment sets a mean square of surface roughness on the organic insulating film to 1.0 nm or less.   The method for manufacturing an electrode substrate according to claim 1, further comprising a step of heat-treating the transparent conductive film after the etching step. The method for manufacturing an electrode substrate according to claim 7 , wherein the heat treatment is performed at 150 ° C. to 220 ° C. An electrode substrate,
An organic insulating film region composed of an organic insulating film having a root mean square surface roughness of 1.0 nm or less;
An inorganic insulating film region composed of an inorganic insulating film provided on the same side as the organic insulating film;
A transparent conductive film in contact with each of the organic insulating film region and the inorganic insulating film region;
An electrode substrate comprising:   The electrode substrate according to claim 9, wherein a mean square of the surface roughness of the organic insulating film is 0.28 nm or more and 1.0 nm or less.   A liquid crystal display device comprising the electrode substrate according to claim 9.

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