JP2007052311A - Electrooptical device and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrooptical device capable of preventing the occurrence of a point defect and line defect due to the disconnection of an upper electrode material by preventing the deformation of an element portion and a holding capacitor portion due to a heat treatment process, and to provide electronic equipment. <P>SOLUTION: In the method for manufacturing the electrooptical device, a tantalum film 6 is patterned to form a first tantalum pattern 6a and a second tantalum pattern 6b having a data line 2, a lower electrode 62 for a holding capacitor, and a common electrode 63. Next, anodic oxidation is performed by using the data line as a feeder to form a thick second tantalum oxide film 7b constituting an oxide film 72 for the holding capacitor only on the surface side of the second tantalum pattern 6b. Then, a thin tantalum oxide film for constituting an oxide film for a nonlinear element is formed only on the surface side of the first tantalum pattern 6a by vapor phase oxidation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an active matrix electro-optical device and an electronic apparatus including the electro-optical device.

  In the active matrix type electro-optical device, a plurality of pixels are formed corresponding to the intersection of the scanning line and the data line formed in the direction intersecting each other. When these plural pixels are viewed as an equivalent circuit, a pixel switching element composed of a TFT (Thin Film Transistor) and a liquid crystal capacitor are connected in series, and a holding capacitor is connected in parallel to the liquid crystal capacitor. (For example, refer to Patent Document 1).

  In the electro-optical device disclosed in Patent Document 1, a pixel electrode and a common electrode are formed on the element substrate, and a liquid crystal is driven using a lateral electric field generated between the pixel electrode and the common electrode. A so-called IPS (In-Plane Switching) mode is employed.

  However, when the TFT is used as the pixel switching element as in the configuration disclosed in Patent Document 1, it is necessary to repeatedly perform a photolithography process and a film forming process including exposure, development, etching, and the like many times. Therefore, there are problems that the manufacturing process is long and the manufacturing cost increases.

To solve these problems, a tantalum alloy layer containing tungsten or the like, a lower electrode for a non-linear element made of a tantalum simple substance film, a non-linear element oxide film made of an anodic oxide film thereof, and a non-linear made of a chromium layer There is an electro-optical device using a TFD (Thin Film Diode) element (non-linear element) having an upper electrode for an element as a pixel switching element (for example, see Patent Document 2).
JP 2000-162602 A JP 07-261200 A

  In an electro-optical device using a TFD element as a pixel switching element, when forming a storage capacitor, it is necessary to form a storage capacitor oxide film thicker than a nonlinear element oxide film. For this reason, after forming a tantalum pattern having a structure in which the lower electrode for the nonlinear element and the lower electrode for the storage capacitor are connected, the tantalum pattern is anodized to form a thin oxide film used as the oxide film for the nonlinear element. Next, the tantalum pattern is etched to separate the lower electrode for the nonlinear element and the lower electrode for the storage capacitor, and then the lower electrode for the storage capacitor is anodized again to form a thick oxide used as a storage capacitor oxide film. It is necessary to form a film. For this reason, when a storage capacitor is added to an electro-optical device using a non-linear element as a pixel switching element, there is a problem that the number of manufacturing steps increases and the advantage that the number of manufacturing steps is small is lost. is there.

  In view of the above problems, an object of the present invention is to provide an electro-optical device manufacturing method capable of reducing manufacturing cost by minimizing an increase in the number of steps even when a storage capacitor is added, and To provide an electro-optical device.

  In order to solve the above-described problems, the present invention includes an element substrate for sandwiching liquid crystal and a counter substrate. The element substrate includes a first wiring and an electric element connected to the first wiring via a nonlinear element. In a method of manufacturing an electro-optical device, in which a pixel electrode connected in common and a common electrode facing the pixel electrode via the liquid crystal are formed, a valve metal film that forms a valve metal film on the element substrate Forming a first pattern including a lower electrode for a non-linear element by patterning the valve metal film, a second pattern including a lower electrode for a storage capacitor and a feeder line connected to the lower electrode for the storage capacitor A lower electrode pattern forming step for forming the patterns separated from each other, and a gas phase oxidation for forming a first oxide film on the surface side of the first pattern and the surface side of the second pattern by gas phase oxidation. Process and power supply An anodic oxidation step for supplying power to the second pattern via the first pattern and forming a second oxide film thicker than the first oxide film on the surface side of the second pattern; An upper electrode including a non-linear element upper electrode facing the non-linear element lower electrode through one oxide film, and a storage capacitor upper electrode facing the storage capacitor lower electrode through the second oxide film And an upper electrode pattern forming step for forming a pattern.

  In the present invention, the valve metal means a metal on which an oxide film is formed by anodic oxidation, and examples thereof include tantalum, niobium, titanium, aluminum, hafnium, zirconium, tungsten, and alloys thereof. In the present invention, vapor phase oxidation means forming an oxide film by reacting with oxygen in the atmosphere, and more specifically, thermal oxidation, high-temperature high-pressure steam oxidation, ozone oxidation, oxygen plasma oxidation, etc. Can be mentioned.

  In the present invention, the first pattern including the lower electrode for the non-linear element and the second pattern including the feeder line connected to the lower electrode for the storage capacitor and the lower electrode for the storage capacitor are already provided in the lower electrode pattern forming step. Are formed as a first oxide film by vapor phase oxidation for a thin nonlinear element oxide film, and as a second oxide film by anodic oxidation for a thick storage capacitor oxide film. That is, anodic oxidation in which an oxide film is selectively formed is used for a thick storage capacitor oxide film, and vapor phase oxidation in which an oxide film is formed as a whole is used for a thin nonlinear element oxide film. For this reason, the valve metal film pattern need not be separated into the non-linear element lower electrode and the storage capacitor lower electrode by patterning after forming a thin oxide film. Therefore, even when a storage capacitor is added, only a gas phase oxidation process that does not require a photolithography process needs to be added, so that the manufacturing cost can be reduced.

  In the present invention, the valve metal film is, for example, a tantalum film.

  The present invention is applied to electro-optical devices such as an IPS (In-Plane Switching) mode and an FFS (Fringe Field Switching) mode that use a lateral electric field generated between the pixel electrode and the common electrode.

  Among these electro-optical devices, when manufacturing an IPS mode electro-optical device, the element substrate is formed using at least one of the lower electrode pattern forming step and the upper electrode pattern forming step. On the other hand, it is preferable to form a second wiring that extends in a direction intersecting with the common electrode and the first wiring and that is connected to the common electrode directly or through another conductive layer. In the present invention, the feeder line may be used as the second wiring.

  In the present invention, it is preferable to perform an annealing process for annealing the element substrate in a hydrogen atom-containing atmosphere after performing at least the gas phase oxidation process and before performing the upper electrode pattern forming process. When such heat treatment is performed, the characteristics of the nonlinear element can be improved.

  In this case, it is preferable to perform the annealing step before performing the anodic oxidation step. When an annealing process in an atmosphere containing hydrogen atoms is performed on an anodized film, the leakage current tends to increase. However, if the annealing process is performed before the anodizing process, a storage capacitor with a small leakage current can be configured. High-contrast images can be displayed. In addition, it is possible to prevent changes in characteristics of the storage capacitor over time.

  In the present invention, after the element substrate is disposed in the gas phase oxidation chamber and the gas phase oxidation step is performed, a gas containing hydrogen atoms is introduced into the gas phase oxidation chamber and the annealing step is performed. preferable. If comprised in this way, the said annealing process can be performed following the said vapor phase oxidation process.

  The electro-optical device according to the present invention is used in an electronic apparatus such as a mobile phone or a mobile computer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In each drawing to be referred to, the scale may be different for each layer or each member in order to make the size recognizable on the drawing. In each figure, regardless of a cross-sectional view or a plan view, a tantalum film constituting a lower electrode for a non-linear element of a TFD element (non-linear element) is shown with a slanting line to the lower right, and for the non-linear element of the TFD element. The chrome film constituting the upper electrode and the like is hatched with an upward slope.

[Embodiment 1]
(overall structure)
FIG. 1 is a block diagram showing an electrical configuration of an electro-optical device to which the present invention is applied. FIG. 2 is a cross-sectional view schematically showing the configuration of the electro-optical device shown in FIG.

  An electro-optical device 1 shown in FIG. 1 is an active matrix type liquid crystal device adopting an IPS mode. In the electro-optical device 1, a scanning line 3 (first wiring) extending in the X direction and a Y-direction are used. A plurality of pixels 10 are arranged in a matrix corresponding to the intersection with the extended data line 2 (second wiring). The data line 2 is connected to the data line driving circuit 12, and the scanning line 3 is connected to the scanning line driving circuit 13. In this embodiment, the nonlinear element 5 is connected to the scanning line 3, and the pixel electrode 83 is connected via the nonlinear element 5. A common electrode 63 is connected to the data line 2. A liquid crystal capacitor 4 is formed between the common electrode 63 and the pixel electrode 83, and the liquid crystal capacitor 4 is connected in series to the nonlinear element 5 in terms of an equivalent circuit. Further, in this embodiment, the storage capacitor 9 is formed between the data line 2 and the pixel electrode 83. In terms of an equivalent circuit, the storage capacitor 9 is connected in series to the nonlinear element 5 and the liquid crystal capacitor. 4 are connected in parallel.

  As shown in FIG. 2, the electro-optical device 1 according to this embodiment includes a pair of substrates arranged to face each other. One substrate is the element substrate 20 on which the nonlinear element 5 and the pixel electrode 83 are formed, and the other substrate is the counter substrate 30. The element substrate 20 and the counter substrate 30 are bonded together by the sealing material 14, and the liquid crystal 11 is sealed inside thereof. In the electro-optical device 1 of this embodiment, the liquid crystal driving IC chip 15 is mounted on the surface of the element substrate 20.

  In this embodiment, since the liquid crystal 11 is driven in the IPS mode, a plurality of scanning lines 3 and a plurality of nonlinear elements 5 connected to the scanning lines 3 are formed on the inner surface of the element substrate 20 as will be described in detail later. The pixel electrode 83 connected to the non-linear element 5 in a one-to-one relationship is formed, and the data line 2, the common electrode 63 and the storage capacitor 9 shown in FIG. 1 are further formed on the inner surface of the element substrate 20. ing. In the element substrate 20, an alignment film 22 made of polyimide or the like is formed on the surface of the pixel electrode 83 or the like. An alignment film 32 made of polyimide or the like is formed on the inner surface of the counter substrate 30. However, unlike the TN mode or VAN mode electro-optical device, in the electro-optical device 1 of this embodiment, the common electrode (counter electrode) is not formed on the inner surface of the counter substrate 30. When the electro-optical device 1 is configured for color display, “R”, “G”, and “B” color filters are formed on the counter substrate 30, but are not directly related to the present invention. The illustration and description thereof are omitted. In addition, a light shielding film called a black matrix or a planarizing film may be formed on the counter substrate 30, and description thereof will be omitted. In addition, optical members such as a polarizing plate and a retardation plate are disposed on the outer surface of the element substrate 20 and the outer surface of the counter substrate 30, and illustration and description of these optical members are also omitted.

(Detailed configuration of element substrate 20)
FIG. 3 is a plan view showing a layout for several pixels in the element substrate used in the electro-optical device to which the present invention is applied. 4 (a), 4 (b), 4 (c), and 4 (d) are electro-optics taken along lines AA ', BB', CC ', and DD' in FIG. 3, respectively. It is sectional drawing which shows typically a structure when an apparatus is cut | disconnected.

  3 and 4A, 4B, 4C, and 4D, in the electro-optical device 1 of the present embodiment, the scanning line 3 (first wiring) extending in the X direction and the Y direction are used. A plurality of pixels 10 are arranged in a matrix corresponding to the intersection with the extended data line 2 (second wiring). The scanning line 3 is a metal wiring made of chromium or the like, and the data line 2 extending in the Y direction is a metal wiring made of tantalum.

  In this embodiment, the nonlinear element 5 is formed in the vicinity of the intersection between the data line 2 and the scanning line 3, and the nonlinear element 5 extends in a direction parallel to the data line 2 and intersects with the scanning line 3. A non-linear element lower electrode 61 is provided. As shown in FIG. 3 and FIGS. 4A and 4B, the nonlinear element oxide film 71 (with a thickness of 20 to 30 nm) is formed on the surface side (both the upper surface and the side surface) of the nonlinear element lower electrode 61. A first tantalum oxide film) is formed. The scanning line 3 passes through the surface of the nonlinear element oxide film 71 as the first nonlinear element upper electrode 81a. The nonlinear element lower electrode 61, the nonlinear element oxide film 71, and the scanning line 3 (first The non-linear element upper electrode 81a) forms the first TFD element 5a. A second non-linear element upper electrode 81b is formed on the surface of the non-linear element oxide film 71 so as to be parallel to the scanning line 3. The non-linear element lower electrode 61, the non-linear element oxide film 71, A second TFD element 5b is formed by the upper electrode 81b for the second nonlinear element. In this way, the nonlinear element 5 has a back-to-back structure in which the first TFD element 5a and the second TFD element 5b are connected in series with opposite polarities.

  As shown in FIG. 3, the second nonlinear element upper electrode 81b of the nonlinear element 5 includes a pixel wiring portion 82 extending in the X direction, a plurality of comb-like pixel electrodes 83 extending in the Y direction, and A storage capacitor upper electrode 84 extending in the X direction and connecting the tip portions of the plurality of pixel electrodes 83 is connected in this order. Here, the second non-linear element upper electrode 81 b, the pixel wiring portion 82, the pixel electrode 83, and the storage capacitor upper electrode 84 are formed of a chromium film formed simultaneously with the scanning line 3.

  In this embodiment, the scanning line 3 (first nonlinear element upper electrode 81a), second nonlinear element upper electrode 81b, pixel wiring portion 82, pixel electrode 83, and storage capacitor upper electrode 84 are made of a chromium film. The ITO film 3 ', 81a', 81b ', 82', 83 'is formed on the upper layer. Here, the ITO film is formed with the same pattern as the chromium film. The ITO film may be formed with a pattern different from that of the chromium film.

  In the pixel 10, a storage capacitor lower electrode 62 is formed by a protruding portion in the X direction from the data line 2, and a plurality of comb-like common electrodes 63 are formed in the Y direction from the storage capacitor lower electrode 62. It extends.

  As shown in FIGS. 3 and 4C, the common electrodes 63 and the pixel electrodes 83 are alternately arranged in the X direction, and drive the liquid crystal 11 therebetween. In other words, the pixel electrode 83, the liquid crystal 11 and the common electrode 63 constitute the liquid crystal capacitor 4 shown in FIG.

  As shown in FIG. 3 and FIG. 4D, a storage capacitor oxide film 72 (second oxide film) is formed on the surface side of the storage capacitor lower electrode 62, and the storage capacitor upper electrode 84 The storage capacitor is opposed to the storage capacitor lower electrode 62 with the storage capacitor oxide film 72 interposed therebetween. In this way, the storage capacitor 9 is configured by the storage capacitor lower electrode 62, the storage capacitor oxide film 72, and the storage capacitor upper electrode 84.

  Again, in FIGS. 3 and 4A, 4B, 4C, and 4D, the data line 2 is held by anodizing the storage capacitor lower electrode 62, as will be described later. Since it is used as a power supply line for forming the capacitor oxide film 72, an oxide film having the same thickness as the storage capacitor oxide film 72 is also formed on the surfaces of the data line 2 and the common electrode 63 during the anodic oxidation. 73 and 74 are formed. Therefore, the oxide film 73 is interposed between the scanning line 3 and the data line 2 at the intersection of the scanning line 3 and the data line 2. Here, the film thickness of the storage capacitor oxide film 72 and the oxide films 73 and 74 is 100 to 250 nm, which is thicker than the nonlinear element oxide film 71.

(Method for manufacturing electro-optical device)
FIGS. 5A and 5B are process diagrams showing the manufacturing process of the element substrate 20 in the manufacturing process of the electro-optical device of the present embodiment, and the element substrate in the manufacturing process of the conventional electro-optical device, respectively. It is process drawing which shows a manufacturing process. FIGS. 6A to 6C and FIGS. 7A and 7B are explanatory views showing the manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device of this embodiment. 6 and 7, the right side area shows a plan view of one pixel, and the left side area shows a cross-sectional view at a position corresponding to the line AA ′ in FIG. 3.

Before describing the details of the manufacturing method with reference to FIGS. 6 and 7, the number of manufacturing steps of the present invention and the number of conventional manufacturing steps will be compared with reference to FIGS. 5 (a) and 5 (b). First, in this embodiment, as shown in FIG. 5A, the following 10 steps are generally performed. ST1: Formation step of the base layer 21 (TaO _x sputter deposition)
ST2: Tantalum film formation process (Ta sputter film formation)
ST3: Lower electrode pattern formation process
(Photolithography process + etching process)
ST4: Anodizing process ST5: Vapor phase oxidizing process ST6: Etching process (for Cr conduction)
ST7: Annealing process for oxide film ST8: Upper electrode pattern forming process ST81: Sputter deposition of Cr ST82: Patterning of Cr
(Photolithography process + etching process)
ST9: ITO pattern formation process ST91: Sputter deposition of ITO ST92: ITO patterning
(Photolithography process + etching process)
ST10: It consists of an annealing process.

On the other hand, in the conventional manufacturing method, as shown in FIG. 5 (b), the following 11 steps ST1: Step of forming the underlayer 21 (TaO _x sputter deposition)
ST2: Tantalum film formation process (Ta sputter film formation)
ST31 ′: Lower electrode pattern forming step
(Photolithography process + etching process)
ST41 ': Anodizing process for forming nonlinear element ST32': Patterning process for separating element part
(Photolithography process + etching process)
ST42 ': Anodizing process for forming auxiliary capacitance ST6: Etching process (for Cr conduction)
ST7: Annealing process for oxide film ST8: Upper electrode pattern forming process ST81: Sputter deposition of Cr ST82: Patterning of Cr
(Photolithography process + etching process)
ST9: ITO pattern formation process ST91: Sputter deposition of ITO ST92: ITO patterning
(Photolithography process + etching process)
ST10: It consists of an annealing process.

  Hereinafter, details of each process will be described. First, as shown in FIG. 6A, in the formation step ST1 of the foundation layer 21, the foundation layer 21 is formed on the entire surface of the element substrate 20 with a tantalum oxide film or the like.

Next, in the tantalum film forming step ST2 (barrier metal film forming step), the tantalum film 6 (barrier metal film) is formed on the entire surface of the element substrate 20. The film thickness of the tantalum film 6 formed here is, for example, about 50 nm to 200 nm. Such a tantalum film 6 can be formed by a sputtering method or the like, and the sputtering method is performed by an RF sputtering device, a magnetron sputtering device, or the like. In such a film forming apparatus, a target of a raw material for the lower electrode (tantalum) is placed in the chamber, the inside of the chamber is depressurized by an exhaust device such as a vacuum pump, and an inert gas such as argon is introduced, A plasma is formed by applying a high-frequency electric field. As a result, positive ions in the plasma are accelerated and collided with the target, and the target material is deposited on the element substrate 20 by the reaction. At that time, if nitrogen N ₂ or oxygen O ₂ is introduced into the chamber together with an inert gas, a nitrogen-containing tantalum film or an oxygen-containing tantalum film can be formed.

  Next, in the lower electrode pattern forming step ST3, as shown in FIG. 6B, the tantalum film 6 is patterned by using a photolithography technique, and the first tantalum pattern 6a including the lower electrode 61 for nonlinear elements and The second tantalum pattern 6b including the data line 2, the storage capacitor lower electrode 62, and the common electrode 63 is formed. Here, the first tantalum pattern 6a and the second tantalum pattern 6b are completely separated.

  Next, in the anodization step ST4, as shown in FIG. 6C, anodization is performed using the data line 2 as a power supply line. As a result, of the first tantalum pattern 6a and the second tantalum pattern 6b, only the surface side of the second tantalum pattern 6b is oxidized, and a thick second tantalum oxide film 7b having a thickness of 100 to 250 nm is formed. It is formed. In the anodic oxidation method performed in this step, the element substrate 20 is immersed in an electrolytic solution (chemical conversion solution) such as an aqueous solution or an alcohol solution of an aromatic carboxylate such as phosphate, citrate, salicylate or phthalate, A voltage is applied between the second tantalum pattern 6b and the cathode plate while facing the cathode plate in the electrolytic solution. Examples of the aromatic carboxylate include ammonium salicylate, ammonium benzoate, ammonium γ-resorcinate, ammonium hydrogen phthalate, diammonium phthalate, and the like.

  Next, in the vapor phase oxidation step ST5, as shown in FIG. 7A, vapor phase oxidation such as thermal oxidation, high temperature high pressure steam oxidation, ozone oxidation, oxygen plasma oxidation, etc. is performed, and the first tantalum pattern 6a is formed. A thin first tantalum oxide film 7a (non-linear element oxide film 71) having a thickness of, for example, about 20 to 30 nm is formed only on the surface side. At this time, since the second tantalum oxide film 7b is already formed on the second tantalum pattern 6b, the second tantalum oxide film 7b is not thickened. Here, thermal oxidation is performed at, for example, 450 to 500 ° C., high-temperature and high-pressure steam oxidation is performed at, for example, 350 to 400 ° C., and ozone oxidation is performed at, for example, about 300 ° C.

  Next, in the etching step ST6 for Cr conduction, a notch (not shown) is formed in the end portion of the data line 2 and the oxide film 73 covering the end, and the tantalum constituting the data line 2 inside the notch. Expose the membrane.

  Next, as an annealing step ST7 for the oxide film, the element substrate 20 is heat-treated at a temperature of 320 to 400 ° C. for about 10 to 120 minutes in an atmosphere containing hydrogen. In such heat treatment, hydrogen is introduced into the first tantalum oxide film 7a (nonlinear element oxide film 71) to improve the film quality and insulation, thereby reducing variations in characteristics of the nonlinear element 5 and aging of element characteristics. To improve stability.

  Next, in the upper electrode pattern forming step ST8, after forming a chromium film on the entire surface of the element substrate 20 (Cr sputter film forming step ST81), the chromium film is shown in FIG. (Cr patterning step ST82), scanning line 3 (first nonlinear element upper electrode 81a), second nonlinear element upper electrode 81b, pixel electrode 83, storage capacitor upper electrode 84, and A terminal (not shown) that conducts to the data line 2 through the notch is formed. In this way, the first TFD element 5a including the first nonlinear element lower electrode 61, the nonlinear element oxide film 71, and the scanning line 3 (first nonlinear element upper electrode 81a), the first The second TFD element 5b including the lower electrode 61 for the non-linear element, the oxide film 71 for the non-linear element, and the second upper electrode 81b for the non-linear element is formed, and the first TFD element 5a and the second TFD element The nonlinear element 5 having a Back-to-Back structure is formed by 5b. The storage capacitor 9 is formed by the storage capacitor lower electrode 62, the storage capacitor oxide film 72, and the storage capacitor upper electrode 84. Further, the pixel electrode 83 is formed to face the common electrode 63.

  Next, in the ITO pattern forming step ST9, although not shown, an ITO film sputter film forming step ST91 and an ITO patterning step ST92 are performed, and the ITO film is formed as shown in FIGS. 3 ', 81a', 81b ', 82', 83 'are formed.

  Next, an annealing step ST10 shown in FIG. 5 is performed to improve the adhesion between the chromium film and the ITO film.

  Thereafter, a polyimide resin or the like is applied to the entire surface of the element substrate 20 and baked, and then a rubbing process is performed to form an alignment film 22 as shown in FIGS. In this way, the element substrate 20 is formed.

  The element substrate 20 manufactured in this manner is bonded to the counter substrate 30 on which the alignment film 32 is formed by the sealing material 14, and then the liquid crystal 11 is injected from the discontinuous portion of the sealing material 14, and then the sealing material 14. The discontinuous portion is sealed with a sealing material. Thereby, the electro-optical device 1 is completed.

(Main effects of this form)
As described above, in the present embodiment, the first tantalum pattern 6a including the lower electrode 71 for the non-linear element, the lower electrode 61 for the storage capacitor, and the data line 2 (feed line) are already provided in the lower electrode pattern forming step ST3. The second tantalum pattern 6b provided is formed in a state of being separated from each other, the thin non-linear element oxide film 71 is formed as a first tantalum oxide film 7a by vapor phase oxidation, and the thick storage capacitor oxide film 72 is formed. A thick second tantalum oxide film 7b is formed by anodic oxidation. That is, an anodic oxidation method capable of selectively forming an oxide film is used for the thick storage capacitor oxide film 72, and a vapor phase oxidation method in which an oxide film is entirely formed is used for the thin non-linear element oxide film 71. Therefore, unlike the conventional manufacturing method shown in FIG. 5B, after forming a thin oxide film on the tantalum pattern in the anodic oxidation step ST41 ′, patterning is performed in the patterning step ST32 ′ to hold the lower electrode for the nonlinear element. There is no need to separate the capacitor lower electrode. Therefore, even when the storage capacitor 9 is added, it is only necessary to add a gas phase oxidation process that does not require a photolithography process, so that the manufacturing cost can be reduced.

[Embodiment 2]
FIG. 8 is a process diagram showing a manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device according to the second embodiment of the present invention. In the first embodiment, after performing the Cr conduction etching step ST6, the oxide film annealing step ST7 is performed. In this embodiment, however, the oxide film annealing step ST7 is performed as shown in FIG. Then, etching step ST6 for Cr conduction is performed. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

[Embodiment 3]
FIG. 9 is a process diagram illustrating a manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device according to the third embodiment of the invention. In the second embodiment, the annealing step ST7 is performed independently when the annealing step ST7 for the oxide film is performed before the Cr conduction etching step ST6. However, as shown in FIG. After the element substrate 20 is disposed and the vapor phase oxidation step ST5 ′ is performed, it is preferable to perform the annealing step by introducing a gas containing hydrogen atoms into the vapor phase oxidation chamber during the temperature drop. With this configuration, the annealing process can be continuously performed following the vapor phase oxidation process, and it is not necessary to perform the annealing process separately by moving the element substrate 20, thereby improving the processing speed for the element substrate 20. can do. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

[Embodiment 4]
FIG. 10 is a process diagram illustrating a manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device according to the fourth embodiment of the invention. FIGS. 11A to 11C, and FIGS. 12A and 12B are explanatory views showing the manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device of this embodiment. 11 and 12, as in FIGS. 6 and 7, the right side area shows a plan view of one pixel, and the left side area at a position corresponding to the line AA ′ in FIG. 3. A cross-sectional view is shown.

Before explaining the details of the manufacturing method with reference to FIGS. 11 and 12, the outline of the manufacturing process of the present invention will be described with reference to FIG. In the first embodiment, the vapor phase oxidation step ST5 is performed after the anodic oxidation step ST4. In this embodiment, in the order ST1 shown in FIG. 10, the formation step of the base layer 21 (TaO _x sputter deposition).
ST2: Tantalum film formation process (Ta sputter film formation)
ST3: Lower electrode pattern formation process
(Photolithography process + etching process)
ST5: Gas phase oxidation process ST4: Anodization process ST6: Etching process (for Cr conduction)
ST7: Annealing process for oxide film ST8: Upper electrode pattern forming process ST81: Sputter deposition of Cr ST82: Patterning of Cr
(Photolithography process + etching process)
ST9: ITO pattern formation process ST91: Sputter deposition of ITO ST92: ITO patterning
(Photolithography process + etching process)
ST10: Perform each step in an annealing step. That is, in this embodiment, after the vapor phase oxidation step ST5, the anodic oxidation step ST4 is performed.

  Hereinafter, details of each process will be described. First, as shown in FIG. 11A, in the formation step ST1 of the foundation layer 21, after the foundation layer 21 is formed on the entire surface of the element substrate 20 with a tantalum oxide film or the like, the element substrate is formed in the tantalum film formation process ST2. A tantalum film 6 is formed on the entire surface 20.

  Next, in the lower electrode pattern forming step ST3, as shown in FIG. 11B, the tantalum film 6 is patterned using a photolithography technique, and the first tantalum pattern 6a including the lower electrode 61 for nonlinear elements is formed. The second tantalum pattern 6b including the data line 2, the storage capacitor lower electrode 62, and the common electrode 63 is formed. Here, the first tantalum pattern 6a and the second tantalum pattern 6b are completely separated.

  Next, in the vapor phase oxidation step ST5, as shown in FIG. 11C, vapor phase oxidation such as thermal oxidation, high-temperature high-pressure steam oxidation, ozone oxidation, oxygen plasma oxidation, etc. is performed, and the first tantalum pattern 6a and A thin first tantalum oxide film 7a having a film thickness of, for example, about 20 to 30 nm is formed on the surface side of the second tantalum pattern 6b. Of the first tantalum oxide film 7 a, the portion formed on the surface of the lower electrode 61 for the non-linear element becomes the non-linear element oxide film 71.

  Next, in the anodizing step ST4, as shown in FIG. 12A, anodizing is performed using the data line 2 as a power supply line. As a result, of the first tantalum pattern 6a and the second tantalum pattern 6b, only the surface side of the second tantalum pattern 6b is oxidized, and the second tantalum oxide film having a thickness of about 100 to 250 nm, for example. 7b is formed.

  The subsequent steps are the same as in the first embodiment. In the etching step ST6, a notch is formed in the end portion of the data line 2 and the oxide film 73 covering the end, and the tantalum film constituting the data line 2 inside the notch. To expose. Next, as an annealing step ST7 for the oxide film, the element substrate 20 is heat-treated at a temperature of 320 to 400 ° C. for about 10 to 120 minutes in an atmosphere containing hydrogen. Such heat treatment improves the film quality and insulation of the first tantalum oxide film 7a (non-linear element oxide film 71), reduces variations in characteristics of the non-linear element 5, and improves the temporal stability of the element characteristics. Let Next, as an upper electrode pattern formation step ST8, a chromium film is formed on the entire surface of the element substrate 20 (Cr sputtering film formation step ST81), and then the chromium film is shown in FIG. In this way (Cr patterning step ST82), the scanning line 3 (first nonlinear element upper electrode 81a), second nonlinear element upper electrode 81b, pixel electrode 83, and storage capacitor upper electrode 84 are formed. To do. Next, in the ITO pattern forming step ST9, an ITO film sputter film forming step ST91 and an ITO patterning step ST92 are performed, and as shown in FIGS. 4A to 4E, the ITO films 3 ′, 81a ′, 81b ', 82' and 83 'are formed. Next, annealing step ST10 shown in FIG. 10 is performed to improve the adhesion between the chromium film and the ITO film. Thereafter, a polyimide resin or the like is applied to the entire surface of the element substrate 20 and baked, and then a rubbing process is performed to form an alignment film 22 as shown in FIGS. In this way, the element substrate 20 is formed.

(Main effects of this form)
As described above, in this embodiment as well, in the lower electrode pattern forming step ST3, the first tantalum pattern 6a including the nonlinear element lower electrode 71, the storage capacitor lower electrode 61, and the data are already provided in the lower electrode pattern forming step ST3. The second tantalum pattern 6b provided with the line 2 (feed line) is formed so as to be separated from each other, and the thin non-linear element oxide film 71 is formed as the first tantalum oxide film 7a by vapor-phase oxidation, and is kept thick. The capacitor oxide film 72 is formed as a thick second tantalum oxide film 7b by anodic oxidation. For this reason, even when the storage capacitor 9 is added, it is only necessary to add a vapor phase oxidation process that does not require a photolithography process, so that the manufacturing cost can be reduced.

[Embodiment 5]
FIG. 13 is a process diagram showing a manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device according to the fifth embodiment of the present invention. In the fourth embodiment, after performing the etching step ST6 for Cr conduction, an annealing step ST7 for the oxide film is performed. However, as shown in FIG. After performing the annealing process ST7, an etching process ST6 for Cr conduction is performed. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

  In this embodiment, the annealing step ST7 is performed after the anodic oxidation step ST4. However, the annealing step ST7 is preferably performed before the anodic oxidation step ST4. When such a method is adopted, the storage capacitor oxide film 72 made of an anodic oxide film is not exposed to annealing in a hydrogen atom-containing atmosphere, so that the leakage current does not increase. Therefore, the storage capacitor 9 with a small leakage current can be configured, and an image with high contrast can be displayed. In addition, the change in characteristics of the storage capacitor 9 over time can be prevented.

[Embodiment 6]
FIG. 14 is a process diagram illustrating a manufacturing process of the element substrate 20 among the manufacturing processes of the electro-optical device according to the sixth embodiment of the present invention. In the fifth embodiment, the annealing step ST7 is performed independently when performing the annealing step ST7 for the oxide film before the Cr conduction etching step ST6. However, as shown in FIG. After the element substrate 20 is disposed in the vapor phase oxidation chamber and the vapor phase oxidation step ST5 ′ is performed, an annealing step is preferably performed by introducing a gas containing hydrogen atoms into the vapor phase oxidation chamber during cooling. . With this configuration, the annealing process can be continuously performed following the vapor phase oxidation process, and it is not necessary to perform the annealing process separately by moving the element substrate 20, thereby improving the processing speed for the element substrate 20. can do.

  Further, since the annealing step is performed before the anodic oxidation step ST4, the storage capacitor oxide film 72 made of the anodic oxide film is not exposed to the annealing in the hydrogen atom-containing atmosphere, so that the leakage current does not increase. Therefore, the storage capacitor 9 with a small leakage current can be configured, and an image with high contrast can be displayed. In addition, the change in characteristics of the storage capacitor 9 over time can be prevented.

[Other embodiments]
In the above embodiment, the scanning line 3 (first wiring) extending in the X direction is a chrome film and the data line 2 (second wiring) extending in the Y direction is a tantalum film, but the scanning line extending in the X direction is used. The line 3 may be a first wiring made of a tantalum film.

  In the above embodiment, the non-linear element 5 in which the first TFD element 5a and the second TFD element 5b are connected in series with opposite polarities is used. However, two TFD elements are connected in parallel with opposite polarities. The nonlinear element 5 may be used as a pixel switching element. Even when such a non-linear element is used, since the current-voltage non-linear characteristic is symmetrical in both positive and negative directions, a high-quality image can be stably displayed even when the inversion driving method is employed.

  In the above embodiment, the common electrode 63 is made of a tantalum film and the pixel electrode 83 is made of a chromium film. For example, the common electrode 63 and the pixel electrode can be electrically connected by connecting the tantalum film and the chromium film. A configuration in which both 83 are tantalum films or a configuration in which both the common electrode 63 and the pixel electrode 83 are chromium films may be employed. In order to electrically connect such a tantalum film and the chromium film, in the manufacturing process of the element substrate 20, the end face of the tantalum film is exposed by forming a notch, and the end face and the chromium film are connected. Therefore, there is no need to perform a separate process for connection.

  In the above embodiment, the present invention is applied to an IPS mode electro-optical device. However, the present invention may be applied to an FFS mode electro-optical device.

  Further, in the above embodiment, a tantalum film is used as the valve metal film, but niobium, titanium, aluminum, hafnium, zirconium, tungsten, or an alloy thereof may be used.

[Example of mounting on electronic devices]
The electro-optical device 1 to which the present invention is applied includes a personal computer (PC) compatible with multimedia, an engineering work station (EWS), a pager, a word processor, a television, a viewfinder type, as well as a mobile phone and a mobile personal computer. In addition to being applicable to electronic devices such as monitor direct-view video tape recorders, electronic notebooks, electronic desk calculators, car navigation devices, POS terminals, touch panels, etc., to construct electronic devices with large screens exceeding 30 inches It can also be used.

1 is a block diagram illustrating an electrical configuration of an electro-optical device to which the present invention is applied. FIG. 2 is a cross-sectional view schematically illustrating a configuration of the electro-optical device illustrated in FIG. 1. 3 is a plan view showing a layout for several pixels in an element substrate used in an electro-optical device to which the present invention is applied. FIG. (A), (b), (c) and (d) respectively show the electro-optical device along the lines AA ′, BB ′, CC ′ and DD ′ in FIG. It is sectional drawing which shows the structure when cut | disconnecting typically. (A), (b) is a process diagram showing a manufacturing process of an element substrate in the manufacturing process of the electro-optical device according to the first embodiment of the present invention, and a manufacturing process of a conventional electro-optical device, respectively. It is process drawing which shows the manufacturing process of an element substrate. (A)-(c) is explanatory drawing which shows the manufacturing process of an element board | substrate among the manufacturing processes of the electro-optical apparatus which concerns on Embodiment 1 of this invention. (A), (b) is explanatory drawing which shows the manufacturing process of an element board | substrate among the manufacturing processes of the electro-optical apparatus which concerns on Embodiment 1 of this invention. FIG. 10 is a process diagram illustrating a manufacturing process of an element substrate among the manufacturing processes of the electro-optical device according to the second embodiment of the invention. FIG. 10 is a process diagram illustrating a manufacturing process of an element substrate among the manufacturing processes of the electro-optical device according to the third embodiment of the invention. FIG. 10 is a process diagram illustrating a process for manufacturing an element substrate in the process for manufacturing an electro-optical device according to Embodiment 4 of the present invention. (A)-(c) is explanatory drawing which shows the manufacturing process of an element substrate among the manufacturing processes of the electro-optical apparatus which concerns on Embodiment 4 of this invention. (A), (b) is explanatory drawing which shows the manufacturing process of an element board | substrate among the manufacturing processes of the electro-optical apparatus which concerns on Embodiment 4 of this invention. FIG. 10 is a process diagram illustrating a manufacturing process of an element substrate among the manufacturing processes of an electro-optical device according to Embodiment 5 of the present invention. FIG. 10 is a process diagram illustrating a manufacturing process of an element substrate among the manufacturing processes of an electro-optical device according to Embodiment 6 of the present invention.

Explanation of symbols

1 .... Electro-optical device 2 .... Data line (second wiring) 3 .... Scanning line (first wiring) 4 .... Liquid crystal capacitance 5 .... Nonlinear element 5a .... First TFD Element, 5b... Second TFD element, 6.. Tantalum film (valve metal), 6a ... First tantalum pattern, 6b ... Second tantalum pattern, 7a ... First tantalum oxide film, 7b .. Second tantalum oxide film, 9 .. Holding capacitor, 10... Pixel, 20 .. Element substrate, 30 .. Opposite substrate, 61 .. Lower electrode for nonlinear element, 62 .. Lower electrode for holding capacitor, ··· Common electrode, 71 ··· Oxide film for nonlinear element, 72 ··· Oxide film for storage capacitor, 81a · · Upper electrode for first nonlinear element, 81b · · Upper electrode for second nonlinear element, 83 · · .Pixel electrode, 84..Upper electrode for storage capacitor

Claims (8)

An element substrate sandwiching liquid crystal and a counter substrate, wherein the element substrate includes a first wiring, a pixel electrode electrically connected to the first wiring through a nonlinear element, and the pixel electrode In the method of manufacturing an electro-optical device in which a common electrode facing the liquid crystal is formed,
A valve metal film forming step of forming a valve metal film on the element substrate;
The valve metal film is patterned so that a first pattern having a lower electrode for a nonlinear element and a second pattern having a lower electrode for a storage capacitor and a feed line connected to the lower electrode for the storage capacitor are mutually connected A lower electrode pattern forming step to form in a separated state;
A vapor phase oxidation step of forming a first oxide film on the surface side of the first pattern and the surface side of the second pattern by vapor phase oxidation;
An anodic oxidation step of performing anodization by supplying power to the second pattern via the feeder and forming a second oxide film thicker than the first oxide film on the surface side of the second pattern; ,
A non-linear element upper electrode facing the non-linear element lower electrode via the first oxide film; and a storage capacitor upper electrode facing the storage capacitor lower electrode via the second oxide film. And an upper electrode pattern forming step of forming an upper electrode pattern.   2. The method of manufacturing an electro-optical device according to claim 1, wherein the valve metal film is a tantalum film.   Using at least one of the lower electrode pattern forming step and the upper electrode pattern forming step, the element substrate extends in a direction intersecting the common electrode and the first wiring. 3. The electro-optical device according to claim 1, wherein a second wiring connected to the common electrode directly or via another conductive layer is formed.   The method of manufacturing an electro-optical device according to claim 3, wherein the feeder line is used as the second wiring.   5. The annealing process of annealing the element substrate in a hydrogen atom-containing atmosphere after performing at least the vapor phase oxidation process and before performing the upper electrode pattern forming process. The method of manufacturing an electro-optical device according to any one of the above.   6. The method of manufacturing an electro-optical device according to claim 5, wherein the annealing step is performed before the anodizing step.   The element substrate is disposed in a gas phase oxidation processing chamber and the gas phase oxidation step is performed, and then the annealing step is performed by introducing a gas containing hydrogen atoms into the gas phase oxidation processing chamber. Item 7. The method for manufacturing an electro-optical device according to Item 5 or 6.   An electro-optical device manufactured by the method according to claim 1.

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