JP3592411B2 - Manufacturing method of thin film diode - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method of manufacturing a thin-film diode applied to a liquid crystal display device, and more particularly to a method of manufacturing a thin-film diode that drives a liquid crystal by controlling a thin-film diode element that is a non-linear resistance element provided in each pixel arranged in a matrix.
[0002]
[Prior art]
Liquid crystal display devices have been put into practical use, and at present, active matrix type liquid crystal display devices that can provide high-quality display image quality are becoming mainstream.
[0003]
Here, the active matrix method refers to a non-linear resistance comprising a thin film transistor (TFT) or a thin film diode (TFD) having a metal-anodized film-metal or metal-anodized film-transparent conductive film structure for each pixel electrode provided in a matrix. The element is used as a switching element.
[0004]
A liquid crystal display device using a thin film diode as a switching element performs display by using a non-linear voltage-current characteristic of the thin film diode and switching a liquid crystal layer connected in series to the thin film diode element.
[0005]
As a conventional technique for manufacturing such a thin film diode, for example, there is a manufacturing method described in JP-A-62-62333.
[0006]
The manufacturing method described in this publication will be described with reference to FIGS. FIG. 12 is a cross-sectional view illustrating a method of manufacturing a thin-film diode according to the related art, and FIG. 13 is a plan view illustrating a method of manufacturing a thin-film diode according to the related art. Note that the cross-sectional view of FIG. 12 shows a cross section taken along line CC of FIG. Hereinafter, description will be made with reference to FIGS. 12 and 13 alternately.
[0007]
First, a material for the lower electrode 13 made of tantalum is formed on the entire surface of the substrate 11 made of glass by a sputtering method.
[0008]
Thereafter, a photoresist is formed on the entire surface of the material of the lower electrode 13 by a spin coating method, exposed and developed using a predetermined photomask, and a photoresist (not shown) formed in a pattern of the lower electrode 13 is formed. ) Is formed. Hereinafter, the entire formation of the photoresist, the exposure processing using the photomask, and the development processing are referred to as photolithography processing.
[0009]
Thereafter, using the patterned photoresist as an etching mask, tantalum, which is the material of the lower electrode 13, is etched to form the lower electrode 13. As shown in FIG. 13, the lower electrode 13 is formed so as to protrude from the signal electrode 25 in a planar pattern shape of the lower electrode 13.
[0010]
Thereafter, the lower electrode 13 is subjected to anodic oxidation treatment to form an anodic oxide film 15 made of a tantalum oxide film (Ta 2 O 5) on the surface of the lower electrode 13. This anodizing treatment is performed in a 0.1 wt% aqueous solution of citric acid by applying a voltage of 36V.
[0011]
After this anodizing treatment, a heating treatment is performed. This heat treatment is performed in air at a temperature of 300 ° C. for 30 minutes.
[0012]
Thereafter, a material for the upper electrode 14 made of chromium and indium tin oxide, which is a transparent conductive film, is formed by a vacuum evaporation method.
[0013]
Thereafter, a photoresist (not shown) is patterned by a photolithography process, and thereafter, the upper electrode 17 is formed by etching the material of the upper electrode 14 using the patterned photoresist as an etching mask.
[0014]
As shown in FIG. 13, the upper electrode 17 is formed such that a partial area of the pixel electrode 19 is opened and the upper electrode 17 overlaps the lower electrode 13.
[0015]
After the patterning of the upper electrode 17, a heat treatment is performed. This heat treatment is performed in air at a temperature of 300 ° C. for 30 minutes.
[0016]
[Problems to be solved by the invention]
The method of manufacturing a thin film diode described above with reference to FIGS. 12 and 13 has a feature that the number of manufacturing processing steps is small, and in particular, the number of times of patterning of the photoresist is as small as two.
[0017]
However, in a liquid crystal display device to which a thin film diode obtained by the method of manufacturing a thin film diode described with reference to FIGS. 12 and 13 is applied, an afterimage phenomenon occurs when switching the display when driving the liquid crystal.
[0018]
This afterimage phenomenon will be described with reference to the graph of FIG. Note that the liquid crystal display device displays normally white. In the graph of FIG. 14, the vertical axis indicates the relative transmittance, and the horizontal axis indicates time.
[0019]
The graph of FIG. 14 shows a change in transmittance when an arbitrary pixel changes the voltage at 5 minute intervals. That is, first, a display voltage (V1) with a transmittance of 50% is applied for 5 minutes (non-selection period: T1), and then a display voltage (V2) with a transmittance of 10% is applied for 5 minutes (selection period: T2). Further, the same voltage (V3) as the voltage (V1) applied in the first non-selection period of T1 is applied again for 5 minutes (non-selection period: T3).
[0020]
The afterimage phenomenon is a phenomenon in which a difference (ΔT) occurs in the transmittance even though the voltages applied in the non-selection period T1 and the non-selection period T3 are equal. The difference ΔT in transmittance in a liquid crystal display device to which a thin-film diode formed by the manufacturing method described with reference to FIGS. 12 and 13 showing the prior art is applied is 5%.
[0021]
The occurrence of the afterimage phenomenon described with reference to FIG. 14 causes the liquid crystal display device to display a display content different from the originally displayed image.
[0022]
When such an afterimage phenomenon occurs, the display quality of the liquid crystal display device is remarkably deteriorated, and this is a serious problem in practical use for the liquid crystal display device.
[0023]
SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a method of manufacturing a thin-film diode with good display quality in a liquid crystal display device using a thin-film diode element by suppressing the occurrence of an afterimage phenomenon.
[0024]
[Means for Solving the Problems]
In order to achieve the above object, a method for manufacturing a thin film diode according to the present invention employs the following means.
[0025]
The method of manufacturing a thin film diode according to the present invention includes forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, patterning the photoresist by photolithography, and forming the patterned photoresist. Forming a lower electrode by etching the lower electrode material using an etching mask; and performing an anodizing treatment using ammonium borate, phosphoric acid, or ammonium phosphate as an anodizing solution to form an anodized film on the surface of the lower electrode. Forming and performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, and performing a photoresist by a photolithography process. Patterning the photoresist and etching the patterned photoresist Characterized by a step of forming the upper electrode and the upper electrode material is etched by using the click.
[0026]
The method of manufacturing a thin film diode according to the present invention includes forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, patterning the photoresist by photolithography, and forming the patterned photoresist. Forming a lower electrode by etching the lower electrode material using an etching mask; and performing an anodizing treatment using ammonium borate, phosphoric acid, or ammonium phosphate as an anodizing solution to form an anodized film on the surface of the lower electrode. Forming and performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and forming a pattern. Etch upper electrode material using photoresist as etching mask The upper electrode is formed by grayed, characterized in that a step of performing heat treatment.
[0027]
The method for manufacturing a thin film diode according to the present invention includes forming a lower electrode material made of a tantalum film on a substrate, forming a photoresist on the lower electrode material, patterning the photoresist by photolithography, and forming the pattern. Forming a lower electrode by etching the lower electrode material using the etched photoresist as an etching mask, and performing anodizing treatment using ammonium borate, phosphoric acid, or ammonium phosphate as an anodizing solution on the surface of the lower electrode. Forming an anodic oxide film of a tantalum oxide film and performing a heat treatment in a vacuum, forming an upper electrode material of a transparent conductive film, performing a heat treatment in a vacuum, and depositing a photoresist on the upper electrode material; Forming and patterning a photoresist by photolithography; Characterized in that a step of forming an upper electrode photoresist was down form the upper electrode material is etched using the etching mask.
[0028]
The method for manufacturing a thin film diode according to the present invention includes forming a lower electrode material made of a tantalum film on a substrate, forming a photoresist on the lower electrode material, patterning the photoresist by photolithography, and forming the pattern. Forming a lower electrode by etching the lower electrode material using the etched photoresist as an etching mask, and performing anodizing treatment using ammonium borate, phosphoric acid, or ammonium phosphate as an anodizing solution on the surface of the lower electrode. Forming an anodic oxide film made of a tantalum oxide film, performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, and performing photolithography processing Pattern the resist and etch the patterned photoresist. An upper electrode to form the upper electrode material is etched using the Ngumasuku, characterized in that a step of performing heat treatment.
[0029]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode, forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming a lower electrode and a signal electrode by etching a lower electrode material using the patterned photoresist as an etching mask; and forming an anode using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Oxidation is performed to form an anodic oxide film on the surface of the lower electrode, and heat treatment is performed in vacuum. Forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and forming the patterned photo. Forming an upper electrode and a pixel electrode by etching the upper electrode material using the resist as an etching mask.
[0030]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode, forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming a lower electrode and a signal electrode by etching a lower electrode material using the patterned photoresist as an etching mask; and forming an anode using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Oxidation is performed to form an anodic oxide film on the surface of the lower electrode, and heat treatment is performed in vacuum. Forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and forming the upper portion using the patterned photoresist as an etching mask. Etching the electrode material to form the upper electrode and the pixel electrode, and performing a heat treatment.
[0031]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode, a method for manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Forming a lower electrode and a signal electrode by etching the tantalum film using the patterned photoresist as an etching mask; and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Anodic oxide film consisting of a tantalum oxide film on the surface of the lower electrode after anodic oxidation Forming and performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, and performing a photoresist by a photolithography process. And forming an upper electrode and a pixel electrode by etching the upper electrode material using the patterned photoresist as an etching mask.
[0032]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode, a method for manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Forming a lower electrode and a signal electrode by etching the tantalum film using the patterned photoresist as an etching mask; and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Anodic oxide film consisting of a tantalum oxide film on the surface of the lower electrode after anodic oxidation Forming, performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, Using the formed photoresist as an etching mask, etching the upper electrode material to form an upper electrode and a pixel electrode, and performing a heat treatment.
[0033]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode. A method of manufacturing a thin film diode includes forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming a lower electrode and a signal electrode by etching a lower electrode material using a patterned photoresist as an etching mask; and forming an anode using ammonium borate or phosphoric acid or ammonium phosphate as an anodic oxidizing solution. Oxidation is performed to form an anodic oxide film on the surface of the lower electrode, and heat treatment is performed in vacuum. Forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and forming the patterned photo. Forming an upper electrode and a pixel electrode by etching the upper electrode material using the resist as an etching mask.
[0034]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode, forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming a lower electrode and a signal electrode by etching a lower electrode material using a patterned photoresist as an etching mask; and anodizing using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. An anodic oxide film consisting of a tantalum oxide film is formed on the surface of the lower electrode by performing A step of performing a heat treatment, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and removing the patterned photoresist. Etching the upper electrode material using the etching mask to form the upper electrode and the pixel electrode, and performing a heat treatment.
[0035]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode, a method for manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Forming a lower electrode and a signal electrode by etching the tantalum film using the patterned photoresist as an etching mask; and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Use anodizing solution as an anodizing solution and apply tan oxide on the surface of the lower electrode. Forming an anodic oxide film made of a transparent film and performing a heat treatment in a vacuum; forming an upper electrode material made of a transparent conductive film; performing a heat treatment in a vacuum to form a photoresist on the upper electrode material Patterning a photoresist by a photolithography process; and etching the upper electrode material using the patterned photoresist as an etching mask to form an upper electrode and a pixel electrode. .
[0036]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode, a method for manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Forming a lower electrode and a signal electrode by etching the tantalum film using the patterned photoresist as an etching mask; and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Anodic oxide film consisting of a tantalum oxide film on the surface of the lower electrode after anodic oxidation Forming, performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, and patterning the photoresist by photolithography, Etching the upper electrode material using the patterned photoresist as an etching mask to form the upper electrode and the pixel electrode, and performing a heat treatment.
[0037]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode.A method of manufacturing a thin film diode includes forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming, etching the lower electrode material using a patterned photoresist as an etching mask to form a lower electrode and a signal electrode, and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution Perform anodic oxidation to form an anodic oxide film on the surface of the lower electrode, and perform heat treatment in vacuum. Forming an upper electrode material made of a transparent conductive film, performing heat treatment in a vacuum, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and forming the pattern. Forming an upper electrode and a pixel electrode by etching an upper electrode material using a photoresist as an etching mask.
[0038]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode, forming a lower electrode material on a substrate, forming a photoresist on the lower electrode material, and patterning the photoresist by a photolithography process. Forming a lower electrode and a signal electrode by etching a lower electrode material using a patterned photoresist as an etching mask; and anodizing using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Process of forming an anodic oxide film on the surface of the lower electrode by performing processing and performing heat treatment in vacuum Forming an upper electrode material composed of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and using the patterned photoresist as an etching mask. Etching a material to form an upper electrode and a pixel electrode, and performing a heat treatment.
[0039]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to this upper electrode, a method of manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Patterning the photoresist, etching the tantalum film using the patterned photoresist as an etching mask to form the lower and signal electrodes, and anodizing ammonium borate or phosphoric acid or ammonium phosphate Anodizing treatment using a tantalum oxide film on the surface of the lower electrode Forming an oxide film and performing a heat treatment in a vacuum; forming an upper electrode material made of a transparent conductive film; performing a heat treatment in a vacuum; forming a photoresist on the upper electrode material; And forming a top electrode and a pixel electrode by etching the upper electrode material using the patterned photoresist as an etching mask.
[0040]
The method for manufacturing a thin-film diode according to the present invention includes a lower electrode formed so as to be connected to the signal electrode, an anodic oxide film formed on the surface of the lower electrode, and an upper electrode formed so as to overlap the lower electrode via the anodic oxide film. And a pixel electrode connected to the upper electrode, a method for manufacturing a thin-film diode comprising: forming a lower electrode material made of a tantalum film on a substrate; forming a photoresist on the lower electrode material; Forming a lower electrode and a signal electrode by etching the tantalum film using the patterned photoresist as an etching mask; and using ammonium borate or phosphoric acid or ammonium phosphate as an anodizing solution. Anodic oxidation consisting of a tantalum oxide film on the surface of the lower electrode Forming a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, Etching the upper electrode material using the patterned photoresist as an etching mask to form the upper electrode and the pixel electrode, and performing a heat treatment.
[0041]
The method of manufacturing a thin-film diode according to the present invention comprises the steps of: forming an island-shaped lower electrode separated from a signal electrode; an anodic oxide film formed on a surface of the lower electrode; and a first electrode formed so as to overlap the lower electrode via the anodic oxide film. A method of manufacturing a thin film diode including an upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode includes forming a lower electrode material on a substrate, and forming a photoresist on the lower electrode material. Patterning a photoresist by photolithography; etching the lower electrode material using the patterned photoresist as an etching mask to form a lower electrode and a signal electrode; Anodizing using an acid or ammonium phosphate as an anodizing solution to form an anodized film on the surface of the lower electrode, A step of performing a heat treatment in the air, forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, and patterning the photoresist by photolithography Forming a first upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode by etching the upper electrode material using the patterned photoresist as an etching mask; It is characterized by having.
[0042]
The method of manufacturing a thin-film diode according to the present invention comprises the steps of: forming an island-shaped lower electrode separated from a signal electrode; an anodic oxide film formed on the surface of the lower electrode; A method of manufacturing a thin film diode including an upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode includes forming a lower electrode material on a substrate, and forming a photoresist on the lower electrode material. Forming a lower electrode and a signal electrode by etching a lower electrode material using the patterned photoresist as an etching mask; and forming an ammonium borate or phosphoric acid. Alternatively, anodizing treatment using ammonium phosphate as an anodizing solution is performed to form an anodized film on the surface of the lower electrode, Performing a heating process, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, patterning the photoresist by photolithography, and removing the patterned photoresist. Forming a first upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode by etching the upper electrode material using an etching mask, and performing a heat treatment. Features.
[0043]
The method of manufacturing a thin-film diode according to the present invention comprises the steps of: forming an island-shaped lower electrode separated from a signal electrode; an anodic oxide film formed on the surface of the lower electrode; A method of manufacturing a thin film diode including an upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode includes forming a lower electrode material made of a tantalum film on a substrate, and forming a photo-electrode on the lower electrode material. Forming a resist and patterning the photoresist by photolithography; etching the tantalum film using the patterned photoresist as an etching mask to form a lower electrode and a signal electrode; Perform anodizing treatment using phosphoric acid or ammonium phosphate as an anodizing solution and apply tantalum oxide on the surface of the lower electrode. Forming an anodic oxide film consisting of, and performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, performing a heat treatment in a vacuum, forming a photoresist on the upper electrode material, Patterning a photoresist by photolithography; etching the upper electrode material using the patterned photoresist as an etching mask to form a first upper electrode, a second upper electrode, and a second upper electrode; And forming a pixel electrode to be connected.
[0044]
The method of manufacturing a thin-film diode according to the present invention comprises the steps of: forming an island-shaped lower electrode separated from a signal electrode; an anodic oxide film formed on the surface of the lower electrode; A method of manufacturing a thin film diode including an upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode includes forming a lower electrode material made of a tantalum film on a substrate, and forming a photo-electrode on the lower electrode material. Forming a resist and patterning the photoresist by photolithography; etching the tantalum film using the patterned photoresist as an etching mask to form a lower electrode and a signal electrode; Perform anodizing treatment using phosphoric acid or ammonium phosphate as an anodizing solution and apply tantalum oxide on the surface of the lower electrode. A process of forming an anodic oxide film made of, and performing a heat treatment in a vacuum, forming an upper electrode material made of a transparent conductive film, forming a photoresist on the upper electrode material, and patterning the photoresist by a photolithography process. Forming and etching the upper electrode material using the patterned photoresist as an etching mask to form a first upper electrode, a second upper electrode, and a pixel electrode connected to the second upper electrode. And a step of performing a heat treatment.
[0045]
The method for manufacturing a thin film diode element according to the present invention comprises anodizing using ammonium borate or phosphoric acid or ammonium phosphate to form an anodized film on the lower electrode surface, and then performing a heat treatment in a vacuum, and A processing step of performing a heat treatment in a vacuum before or after the pattern formation of the upper electrode made of an electrode film is employed.
[0046]
As a result of employing such a processing step, in the method for manufacturing a thin film diode of the present invention, it is possible to suppress the occurrence of an afterimage phenomenon and obtain a liquid crystal display device having good display quality.
[0047]
The inventors presume the reason why the occurrence of the afterimage phenomenon can be suppressed as described below. That is, in the anodic oxidation treatment using ammonium borate, phosphoric acid or ammonium phosphate, boron or phosphorus impurities are taken into the anodic oxide film as anions.
[0048]
Here, a large amount of boron and phosphorus taken into the anodized film during the anodizing treatment are taken in the vicinity of the surface of the anodized film. After that, when heat treatment is performed in a vacuum atmosphere, diffusion of oxygen from the anodic oxide film to the lower electrode material occurs.
[0049]
Then, when comparing the case where the heat treatment was performed in vacuum at the same temperature and the same time, the boron and phosphorus of the present invention were taken in from the film in which a trace amount of carbon was taken into the film of the conventional anodic oxide film using citric acid. In the anodic oxide film thus formed, the amount of diffusion of oxygen on the surface of the anodic oxide film in the direction of the lower electrode material is particularly large.
[0050]
The main cause of the afterimage phenomenon occurring in the prior art is a change in element characteristics during driving of the thin film diode. It is considered that this change in device characteristics is correlated with the electron density trapped by the deep level and surface level traps existing in the anodic oxide film and at the interface between the upper electrode and the lower electrode.
[0051]
A trap that causes a change in element characteristics of the thin-film diode is considered to be generated by excess oxygen in the anodic oxide film and at the interface between the upper electrode and the lower electrode. Therefore, it is desirable to eliminate the excess oxygen.
[0052]
Therefore, compared with the anodic oxide film in which carbon is incorporated in the film in the prior art, the effect of the heat treatment in a vacuum is more effective in the anodic oxide film in which boron or phosphorus is incorporated, especially in the upper electrode side. Medium and the oxygen diffusion amount is large as described above. As a result, heat treatment in a vacuum atmosphere is highly effective in reducing the trap density that causes a change in device characteristics of the thin film diode.
[0053]
In the case of a thin-film diode using a metal film as the upper electrode, if the upper electrode is formed after the anodic oxide film is subjected to heat treatment in vacuum, the current-voltage of the thin-film diode increases due to the increase in oxygen defects that occur simultaneously with the excess oxygen diffusion of the anodic oxide film. There is an inconvenience that leakage occurs in the characteristics.
[0054]
In contrast, in the thin-film diode of the present invention in which a transparent conductive film is applied as the upper electrode, since the transparent conductive film is an oxide, the heat treatment in a vacuum performed after the formation of the transparent conductive film allows the transparent conductive film to be removed. Oxygen diffusion into the anodic oxide film occurs.
[0055]
By controlling the heat treatment of the anodic oxide film in vacuum and the heat treatment of the transparent conductive film in a vacuum atmosphere under optimal conditions, the excess oxygen in the anodic oxide film and the oxygen deficiency that governs pool Frenkel conduction are controlled. As a result, the change in the element characteristics of the thin film diode is minimized, and no leak occurs in the current-voltage characteristics.
[0056]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a method for manufacturing a thin-film diode in the best mode for carrying out the present invention will be described with reference to the drawings. 1 to 3 are cross-sectional views illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention, and FIG. 4 is a plan view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention. 1 to 3 are sectional views taken along line AA of FIG.
[0057]
First, as shown in FIG. 1, a tantalum film having a thickness of 100 nm is formed as a material of the lower electrode 13 on the entire surface of the insulating glass substrate 11. This tantalum film is formed by a sputtering process in an argon gas atmosphere.
[0058]
Thereafter, a positive photoresist 27 is formed on the entire surface of the material of the lower electrode 13 by a spin coating method, and a photolithography process including an exposure process and a development process is performed using a photomask to pattern the photoresist. Then, a photoresist 27 is formed in a pattern shape of the lower electrode 13 and the signal electrode 25.
[0059]
Thereafter, as an etching gas, 200 cc / min of sulfur hexafluoride, 20 cc / min of helium, and 30 cc / min of oxygen were introduced into the etching chamber of the etching apparatus having the parallel plate electrode structure. The pressure is maintained at 50 mTorr, high-frequency power of 1 KW is applied, and the tantalum film as the material of the lower electrode 13 is etched using the photoresist 27 as an etching mask to form the lower electrode 13 and the signal electrode 25 of the thin-film diode.
[0060]
The planar pattern of the lower electrode 13 and the signal electrode 25 after the etching process is such that the lower electrode 13 protrudes from the signal electrode 25 as shown in the plan view of FIG.
[0061]
Next, as shown in FIG. 2, an anodic oxide film 15 is formed on the surface of the lower electrode 13. The anodic oxidation treatment for forming the anodic oxide film 15 is performed using an ammonium borate solution as an anodic oxidation solution.
[0062]
At this time, the anodic oxide film 15 is formed with a anodic oxidation voltage of 36 V, a voltage increase of 0.2 V / min, and a hold voltage of one hour so as to have a thickness of 70 nm. The illustration of the anodic oxide film 15 is omitted in the plan view of FIG.
[0063]
Then, the substrate 11 is immersed in an oxidation tank filled with an anodic oxidizing solution using platinum as a cathode and the lower electrode 13 as an anode, and the above-described DC voltage is applied from a DC power supply via the signal electrode 25.
[0064]
After that, heat treatment is performed in a vacuum. The heat treatment conditions at this time are as follows: ^-5 The process is performed under the conditions of Torr or less, a temperature of 450 ° C., and a time of 60 to 120 minutes.
[0065]
Thereafter, a transparent electrode film made of indium tin oxide is formed on the entire surface as a material of the upper electrode 17. This indium tin oxide is formed to a thickness of 100 nm by a sputtering method in which an argon gas containing 0.5 to 1% of oxygen is introduced into a sputtering chamber and the sputtering pressure is controlled at 10 mTorr.
[0066]
After that, heat treatment is performed in a vacuum. The heat treatment conditions at this time are as follows: ^-5 The operation is performed under the conditions of Torr or lower, a temperature of 330 ° C. to 350 ° C., and a time of 180 minutes.
[0067]
Next, a photoresist 27 is formed on the entire surface of the material of the upper electrode 17 by a spin coating method, and a photolithography process including an exposure process and a development process is performed using a photomask, so that the photoresist 27 is formed on the upper electrode 17 and the pixel electrode. A pattern is formed in a 19 shape.
[0068]
Next, as shown in FIG. 3, the material of the upper electrode 17 is patterned by using the photoresist 27 as an etching mask to form the upper electrode 17 and the pixel electrode 19. The etching of the material of the upper electrode 17 made of indium tin oxide is performed by wet etching using a mixed solution of ferric chloride and hydrochloric acid.
[0069]
Thereafter, the photoresist 27 used as the etching mask is removed by a wet stripping method using a mixed solution of sulfuric acid and hydrogen peroxide.
[0070]
The planar pattern of the upper electrode 17 and the pixel electrode 19 extends a partial area of the pixel electrode 19 and forms the upper electrode 17 so as to overlap the lower electrode 13 as shown in the plan view of FIG.
[0071]
Thereafter, a protective film 21 made of tantalum oxide is formed on the entire surface. This protective film 21 is formed to a thickness of 100 nm by a sputtering method in which an argon gas containing 3% of oxygen is introduced into a vacuum chamber at 5 mTorr.
[0072]
The protective film 16 is formed for the purpose of preventing a short circuit between the signal electrode 25 and the pixel electrode 19 of the substrate 11 on which the thin-film diode element is formed and the scanning electrode of the opposite substrate facing the substrate 11. are doing.
[0073]
As a result, it is possible to form a thin-film diode element having a lower electrode 13 made of a tantalum film, an anodic oxide film 15 made of a tantalum oxide film, and an upper electrode 17 made of an indium tin oxide film which is a transparent conductive film.
[0074]
The afterimage phenomenon when using the thin-film diode formed by the above-described method for manufacturing a thin-film diode will be described with reference to the graph of FIG.
[0075]
Similar to the graph of FIG. 14 illustrating the after-image phenomenon of the prior art, the graph of FIG. 11 shows a liquid crystal display device having a thin film diode formed by the manufacturing method according to the embodiment of the present invention, in which the voltage is changed at 5 minute intervals. Shows the change in the transmittance when it is turned on. Note that the liquid crystal display device displays normally white. In the graph of FIG. 11, the vertical axis indicates the relative transmittance, and the horizontal axis indicates time.
[0076]
First, a display voltage (V1) with a transmittance of 50% is applied for 5 minutes (non-selection period: T1), and then a display voltage (V2) with a transmittance of 10% is applied for 5 minutes (selection period: T2). Further, the same voltage (V3) as the voltage (V1) applied again during the first non-selection period of T1 is applied for 5 minutes (non-selection period: T3).
[0077]
As described above, the afterimage phenomenon is a phenomenon in which a difference (ΔT) occurs in the transmittance even though the voltages applied in the non-selection period T1 and the non-selection period T3 are equal.
[0078]
By using the thin-film diode formed by the manufacturing method of the embodiment of the present invention described with reference to FIGS. 1 to 4 as a switching element of a liquid crystal display device, the difference in transmittance (ΔT) is shown in the graph of FIG. As shown, it decreases to less than 1%. Further, the difference in transmittance (ΔT) also decreases rapidly with time.
[0079]
Further, a liquid crystal display panel was formed using the thin film diode formed by the above-described manufacturing method, and an actual image was displayed. As a result, there was a clear difference between the liquid crystal display panel formed by the conventional technique and the display quality.
[0080]
In the method of manufacturing a thin film diode according to the present invention described above, anodizing treatment is performed using ammonium borate, phosphoric acid, or ammonium phosphate to form an anodized film 15 on the surface of the lower electrode 13 and then heat in vacuum. Processing is performed, and a heating step is performed in a vacuum before or after forming the pattern of the upper electrode 17 made of a transparent electrode film.
[0081]
As a result of employing such processing steps, in the method of manufacturing a thin-film diode of the present invention, as described with reference to the graph of FIG. 11, the occurrence of the afterimage phenomenon is suppressed, and a liquid crystal display device with good display quality is obtained. be able to.
[0082]
The reason why the occurrence of the afterimage phenomenon can be suppressed is considered as described below. In the anodic oxidation treatment using ammonium borate, phosphoric acid, or ammonium phosphate, impurities such as boron and phosphorus are taken into the film of the anodic oxide film 15 as anions.
[0083]
Here, a large amount of boron and phosphorus taken into the anodic oxide film 15 during the anodic oxidation treatment are taken in the vicinity of the surface of the anodic oxide film 15. After that, when heat treatment is performed in a vacuum atmosphere, diffusion of oxygen from the anodic oxide film 15 to the lower electrode 13 occurs.
[0084]
Then, when comparing the case where the heat treatment was performed in vacuum at the same temperature and the same time, the boron and phosphorus of the present invention were taken in from the film in which a trace amount of carbon was taken into the film of the conventional anodic oxide film using citric acid. In the anodic oxide film 15 thus obtained, the amount of diffusion of oxygen on the surface of the anodic oxide film 15 in the direction of the lower electrode 13 is particularly large.
[0085]
The main cause of the afterimage phenomenon occurring in the prior art is a change in element characteristics during driving of the thin film diode. It is considered that this change in device characteristics is correlated with the electron density trapped by the deep level and surface level traps existing in the anodic oxide film 15 and at the interface between the upper electrode 17 and the lower electrode 13.
[0086]
A trap that causes a change in element characteristics of the thin-film diode is considered to be generated by excess oxygen in the anodic oxide film 15 and at the interface between the upper electrode 17 and the lower electrode 13. Therefore, it is desirable to eliminate the excess oxygen.
[0087]
Therefore, as compared with the anodic oxide film in which carbon is taken in the film in the prior art, the effect of the heat treatment in a vacuum is more effective for the anodic oxide film 15 in which boron or phosphorus is taken in, in particular, the anode in the upper electrode 17 side. It is large in the oxide film and the oxygen diffusion amount is large as described above. As a result, heat treatment in a vacuum atmosphere is highly effective in reducing the trap density that causes a change in device characteristics of the thin film diode.
[0088]
In the case of a thin film diode using a metal film as the upper electrode 17, if the upper electrode 17 is formed after the anodic oxide film 15 is subjected to a heat treatment in vacuum, the oxygen deficiency generated simultaneously with the excess oxygen diffusion of the anodic oxide film 15 increases the thin film diode. There is a disadvantage that the current-voltage characteristic of the above does not leak.
[0089]
On the other hand, in the thin-film diode using a transparent conductive film as the upper electrode 17 of the present invention, since this transparent conductive film is an oxide, the transparent conductive film is subjected to a heat treatment in vacuum performed after the formation of the transparent conductive film. Oxygen diffusion from the silicon to the anodic oxide film 15 occurs.
[0090]
By performing the heat treatment of the anodic oxide film 15 in a vacuum and the heat treatment of the transparent conductive film in a vacuum atmosphere under optimal conditions, the excess oxygen in the anodic oxide film 15 and the oxygen deficiency governing the pool Frenkel conduction are obtained. To minimize the change in element characteristics of the thin-film diode, and no leak occurs in the current-voltage characteristics.
[0091]
In the embodiment described with reference to FIGS. 1 to 3 and 4 described above, after the formation of the indium tin oxide film of the transparent conductive film as the material of the upper electrode 17 and the pixel electrode 19, and before the patterning thereof, The embodiment has been described in which the heat treatment is performed in a vacuum.
[0092]
However, in the method of manufacturing a thin film diode according to the present invention, even if the embodiment in which the photolithography process and the etching process are performed and the heating process is performed in a process after patterning the upper electrode 17 and the pixel electrode 19 is adopted, The inventors have confirmed through experiments that the same effects as described can be obtained.
[0093]
Next, a method of manufacturing a thin-film diode element in an embodiment different from the above description will be described with reference to FIGS. 5 to 7 and FIGS. The method for manufacturing a thin film diode element in the embodiment described below is a case where a plurality of thin film diodes are formed between a pixel electrode and a signal electrode.
[0094]
5 to 7 are cross-sectional views illustrating a method of manufacturing a thin-film diode according to an embodiment of the present invention in the order of steps. FIGS. 8 to 10 are plan views illustrating a method of manufacturing a thin-film diode according to the embodiment of the present invention in the order of steps. is there. 5 to 7 are sectional views taken along line BB of FIG.
[0095]
First, as shown in FIG. 5, a tantalum film having a thickness of 100 nm is formed as a material of the lower electrode 13 on the entire surface of the insulating glass substrate 11. This tantalum film is formed by a sputtering process in an argon gas atmosphere.
[0096]
Thereafter, a positive photoresist 27 is formed on the entire surface of the material of the lower electrode 13 by a spin coating method, and a photolithography process including an exposure process and a development process is performed using a photomask to pattern the photoresist. Then, a photoresist 27 is formed in a pattern shape of the lower electrode 13 and the signal electrode 25.
[0097]
Thereafter, as an etching gas, 200 cc / min of sulfur hexafluoride, 20 cc / min of helium, and 30 cc / min of oxygen were introduced into the etching chamber of the etching apparatus having the parallel plate electrode structure. The pressure is maintained at 50 mTorr, high-frequency power of 1 KW is applied, and the tantalum film as the material of the lower electrode 13 is etched using the photoresist 27 as an etching mask to form the lower electrode 13 and the signal electrode 25 of the thin-film diode.
[0098]
The planar pattern of the lower electrode 13 and the signal electrode 25 after this etching process is such that the lower electrode 13 projects from the signal electrode 25 in an L-shape as shown in the plan view of FIG.
[0099]
Next, as shown in FIG. 6, an anodic oxide film 15 is formed on the surface of the lower electrode 13. The anodic oxidation treatment for forming the anodic oxide film 15 is performed using an ammonium borate solution as an anodic oxidation solution.
[0100]
At this time, the anodized film 15 is formed with an anodized voltage of 18 V so as to have a thickness of 38 nm, a voltage increase at a rate of 0.2 V / min, and a hold voltage of one hour.
[0101]
Then, the substrate 11 is immersed in an oxidation tank filled with an anodic oxidizing solution using platinum as a cathode and the lower electrode 13 as an anode, and the above-described DC voltage is applied from a DC power supply via the signal electrode 25.
[0102]
After that, heat treatment is performed in a vacuum. The heat treatment conditions at this time are as follows: ^-5 The process is performed under the conditions of Torr or less, a temperature of 450 ° C., and a time of 60 to 120 minutes.
[0103]
Thereafter, a transparent electrode film made of indium tin oxide is formed on the entire surface as a material of the upper electrode 17. This indium tin oxide is formed to a thickness of 100 nm by a sputtering method in which an argon gas containing 0.5 to 1% of oxygen is introduced into a sputtering chamber and the sputtering pressure is controlled at 10 mTorr.
[0104]
After that, heat treatment is performed in a vacuum. The heat treatment conditions at this time are as follows: ^-5 The operation is performed under the conditions of Torr or lower, a temperature of 330 ° C. to 350 ° C., and a time of 180 minutes.
[0105]
Next, a photoresist 27 is formed on the entire surface of the material of the upper electrode 17 by a spin coating method, and a photolithography process including an exposure process and a development process is performed using a photomask, and the photoresist 27 is formed on the first upper electrode 17a. And the second upper electrode 17b and the pixel electrode 19 are patterned.
[0106]
Next, as shown in FIG. 7, the first upper electrode 17a, the second upper electrode 17b, and the pixel electrode 19 are formed by patterning the material of the upper electrode 17 using the photoresist 27 as an etching mask. The etching of the material of the upper electrode 17 made of indium tin oxide is performed by wet etching using a mixed solution of ferric chloride and hydrochloric acid.
[0107]
Thereafter, the photoresist 27 used as the etching mask is removed by a wet stripping method using a mixed solution of sulfuric acid and hydrogen peroxide.
[0108]
The planar pattern shape of the first upper electrode 17a, the second upper electrode 17b, and the pixel electrode 19 is such that a partial area of the pixel electrode 19 is extended to form the lower electrode 13 as shown in the plan view of FIG. A second upper electrode 17b is formed so as to overlap, and a first upper electrode 17a is formed in a region overlapping with the signal electrode 25 and projecting so as to overlap the lower electrode 13. The illustration of the anodic oxide film is omitted in the plan view of FIG.
[0109]
Thereafter, as shown in the sectional view of FIG. 7, a protective film 21 made of tantalum oxide is formed on the entire surface of the substrate 11. This protective film 21 is formed to a thickness of 100 nm by a sputtering method in which an argon gas containing 3% of oxygen is introduced into a vacuum chamber at 5 mTorr.
[0110]
The protective film 16 is formed for the purpose of preventing the occurrence of a short circuit between the signal electrode 25 and the pixel electrode 19 of the substrate 11 on which the thin film diode element is formed and the scanning electrode of the counter substrate facing the substrate 11. are doing.
[0111]
Thereafter, a photoresist 27 is formed on the entire surface by a spin coating method, and a photolithography process including an exposure process and a development process is performed using a photomask to pattern the photoresist. A pattern is formed so that an opening is formed.
[0112]
As shown in FIG. 10, the opening region 29 is patterned so as to be located at a bent portion of the lower electrode 13 projecting from the signal electrode 25 in an L-shape.
[0113]
Thereafter, using the photoresist 27 as an etching mask, etching is performed at a flow rate of 200 cc / min of sulfur hexafluoride, 20 cc / min of helium, and 30 cc / min of oxygen in an etching chamber of an etching apparatus having a parallel plate electrode structure. The photoresist is introduced into the chamber, the pressure is kept at 50 mTorr, and a high frequency power of 1 kW is further applied to pattern the tantalum oxide as the protective film 21 using the photoresist 27 as an etching mask.
[0114]
Subsequently, the anodic oxide film 15 and the lower electrode 13 in the opening region are removed by etching. As a result, the lower electrode 13 having the island-shaped pattern shape separated from the signal electrode 25 can be patterned.
[0115]
As a result, it has a lower electrode 13 made of a tantalum film, an anodic oxide film 15 made of a tantalum oxide film, and an upper electrode 17 made of an indium tin oxide film which is a transparent conductive film. And two thin film diode elements can be formed therebetween.
[0116]
Here, the thin-film diode formed between the signal electrode 25 and the pixel electrode 19 has a first thin-film diode element having an indium tin oxide-tantalum oxide-tantalum structure and a thin-film diode having a tantalum-tantalum oxide-indium tin oxide structure. 2 thin film diode elements.
[0117]
That is, the current path flowing from the signal electrode 25 to the pixel electrode 19 flows from the indium tin oxide → tantalum oxide → tantalum of the first thin film diode element to the tantalum → tantalum oxide → indium tin oxide of the second thin film diode element. Will be.
[0118]
Therefore, the connection of the thin-film diode element from the signal electrode 25 to the pixel electrode 19 and the connection of the thin-film diode element from the pixel electrode 19 to the signal electrode 25 can be formed in a symmetrical structure.
[0119]
By employing the back-to-back structure of the two thin-film diode elements, the current-voltage characteristics of the thin-film diode element are symmetrical on the plus side and the minus side of the applied voltage.
[0120]
Therefore, there is an advantage that the afterimage phenomenon due to the fixed pattern of the liquid crystal display device can be improved, and the driving power supply can be reduced in cost.
[0121]
The afterimage phenomenon when using the thin film diode formed by the method for manufacturing the thin film diode described with reference to FIGS. 5 to 7 and FIGS. 8 to 10 will be described with reference to the graph of FIG.
[0122]
Similar to the graph of FIG. 14 illustrating the after-image phenomenon of the prior art, the graph of FIG. 11 shows a liquid crystal display device having a thin film diode formed by the manufacturing method according to the embodiment of the present invention, in which the voltage is changed at 5 minute intervals. Shows the change in the transmittance when it is turned on. Note that the liquid crystal display device displays normally white. In the graph of FIG. 11, the vertical axis indicates the relative transmittance, and the horizontal axis indicates time.
[0123]
First, a display voltage (V1) with a transmittance of 50% is applied for 5 minutes (non-selection period: T1), and then a display voltage (V2) with a transmittance of 10% is applied for 5 minutes (selection period: T2). Further, the same voltage (V3) as the voltage (V1) applied again during the first non-selection period of T1 is applied for 5 minutes (non-selection period: T3).
[0124]
As described above, the afterimage phenomenon is a phenomenon in which a difference (ΔT) occurs in the transmittance even though the voltages applied in the non-selection period T1 and the non-selection period T3 are equal.
[0125]
By using the thin film diode formed by the manufacturing method of the embodiment of the present invention described with reference to FIGS. 5 to 7 and FIGS. 8 to 10 as a switching element of a liquid crystal display device, a difference in transmittance (ΔT) is obtained. Decreases to 1% or less as shown in the graph of FIG. Further, the difference in transmittance (ΔT) also decreases rapidly with time.
[0126]
Further, a liquid crystal display panel was formed using the thin film diode formed by the above-described manufacturing method, and an actual image was displayed. As a result, there was a clear difference between the liquid crystal display panel formed by the conventional technique and the display quality.
[0127]
In the method of manufacturing the thin-film diode element according to the present invention described above, the afterimage phenomenon and the occurrence of the leak in the current-voltage characteristic are suppressed for the reason described above.
[0128]
In the embodiment described with reference to FIGS. 5 to 7 and FIGS. 8 to 10 described above, after forming the indium tin oxide film of the transparent conductive film as the material of the upper electrode 17 and the pixel electrode 19, the patterning thereof is performed. The embodiment in which the heat treatment is performed has been described above.
[0129]
However, in the method of manufacturing a thin film diode according to the present invention, even if the embodiment in which the photolithography process and the etching process are performed and the heating process is performed in a process after patterning the upper electrode 17 and the pixel electrode 19 is adopted, The inventors have confirmed through experiments that the same effects as described can be obtained.
[0130]
In the embodiment described above with reference to FIGS. 1 to 11, an example in which ammonium borate is used as the anodic oxidizing solution has been described, but the effects described above can be obtained by using phosphoric acid or ammonium phosphate. The inventors have confirmed this.
[0131]
In the embodiment described above with reference to FIGS. 1 to 11, an example in which a tantalum film is used as the material of the lower electrode 13 has been described, but a tantalum film containing nitrogen, carbon, silicon, niobium, or aluminum may be used. The inventors have confirmed that the described effect can be obtained.
[0132]
In the embodiment described above with reference to FIGS. 1 to 11, an example in which indium tin oxide (ITO) is used as the material of the upper electrode 17 has been described. However, indium oxide (In 2 O 3), zinc oxide (ZnO 2), and oxide The inventors have confirmed that the effects described above can be obtained even when an oxide containing tin (SnO2) or indium as a main component is used.
[0133]
In the embodiment described above with reference to FIGS. 1 to 11, an example in which a tantalum oxide film is used as the material of the protective film 21 has been described. However, even if a silicon oxide film, a silicon nitride film, or a silicon oxynitride film is used, The inventors have confirmed that the described effect can be obtained.
[0134]
In the embodiment described above with reference to FIGS. 1 to 11, an example in which a tantalum oxide film is used as the material of the protective film 21 has been described. However, the effect described above can be obtained by using coated glass (SOG). The inventors have confirmed this. The coated glass film is a mixture of silicon oxide and a solvent. After being formed on the substrate 11 by a spin coating method, the coated glass film is heated at a temperature of 250 ° C. to 300 ° C. to evaporate the solvent in the coated glass film. Form.
[0135]
In the embodiment described above with reference to FIGS. 1 to 11, the example in which the heat treatment is performed in a vacuum is described. However, the heat treatment is performed in an inert atmosphere of nitrogen, argon, helium, xenon, or a reducing atmosphere of hydrogen. The inventors have confirmed that the above-described effects can be obtained.
[0136]
In the embodiment described above with reference to FIGS. 1 to 11, the heat treatment temperature is 450 ° C. and the embodiment is performed at 330 ° C. to 350 ° C., but the effect described above can be obtained even at 250 ° C. to 500 ° C. The inventors have confirmed that they can be obtained.
[0137]
Further, in the embodiment described above with reference to FIGS. 1 to 11, an example in which one or two thin film diodes are provided between the signal electrode 25 and the pixel electrode 19 has been described. The present inventors have confirmed that the above-described effects can be obtained even if formed.
[0138]
A manufacturing method for simply forming a liquid crystal display panel will be described above. An alignment film is formed on each of the substrate 11 on which the thin film diode element is formed and the opposite substrate on which the scanning electrode is formed, and a rubbing process is performed to perform an alignment process on the alignment film. Further, the two substrates are bonded together using a sealing material via a spacer made of glass fiber, a liquid crystal is injected between the substrates, and a polarizing plate is further provided outside each of the substrates so that their polarization axes are orthogonal to each other. Panel.
[0139]
【The invention's effect】
As is apparent from the above description, in the method for manufacturing a thin film diode element according to the embodiment of the present invention, anodizing treatment is performed using ammonium borate, phosphoric acid, or ammonium phosphate to form an anodized film on the lower electrode surface. After the formation, a heat treatment is performed in a vacuum, and a heat treatment is performed in a vacuum before or after forming the pattern of the upper electrode made of the transparent electrode film.
[0140]
As a result of employing such a processing step, in the method for manufacturing a thin film diode of the present invention, it is possible to suppress the occurrence of an afterimage phenomenon and obtain a liquid crystal display device having good display quality.
[0141]
By performing the heat treatment of the anodic oxide film in a vacuum and the heat treatment of the transparent conductive film in a vacuum atmosphere under optimal conditions, the method for manufacturing a thin film diode element according to the embodiment of the present invention provides Excess oxygen in the film and oxygen deficiency that governs Poole-Frenkel conduction are controlled to minimize the change in element characteristics of the thin-film diode, and no leak occurs in current-voltage characteristics.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 3 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 4 is a plan view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 5 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 6 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 7 is a cross-sectional view illustrating a method for manufacturing a thin-film diode according to an embodiment of the present invention.
FIG. 8 is a plan view illustrating the method for manufacturing the thin-film diode in the embodiment of the present invention.
FIG. 9 is a plan view illustrating the method for manufacturing the thin-film diode in the embodiment of the present invention.
FIG. 10 is a plan view illustrating the method for manufacturing the thin-film diode in the embodiment of the present invention.
FIG. 11 is a graph for explaining an afterimage phenomenon in a liquid crystal display device to which a thin film diode element formed by a method of manufacturing a thin film diode according to an embodiment of the present invention is applied, in which the vertical axis indicates relative transmittance and the horizontal axis indicates Indicates time.
FIG. 12 is a cross-sectional view illustrating a method of manufacturing a thin-film diode according to a conventional technique.
FIG. 13 is a plan view illustrating a method for manufacturing a thin-film diode according to a conventional technique.
FIG. 14 is a graph for explaining an afterimage phenomenon in a liquid crystal display device to which a thin film diode element formed by a method of manufacturing a thin film diode according to a conventional technique is applied, in which the vertical axis indicates relative transmittance and the horizontal axis indicates time. .
[Explanation of symbols]
11 Substrate
13 Lower electrode
15 Anodized film
17 Upper electrode
19 pixel electrode
21 Protective film
25 signal electrode

Claims (7)

A lower electrode connected to the signal electrode, an anodic oxide film disposed on the lower electrode, an upper electrode overlapping the anodic oxide film, and a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode.
Anodizing step of forming the anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution,
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
A second heat treatment step performed in a vacuum after forming an upper electrode material made of a transparent electrode film that is a transparent conductive oxide ;
Forming a pattern of the upper electrode material to form the upper electrode and the pixel electrode after the second heat treatment step. A lower electrode connected to the signal electrode, an anodic oxide film disposed on the lower electrode, an upper electrode overlapping the anodic oxide film, and a method of manufacturing a thin film diode including a pixel electrode connected to the upper electrode.
Anodizing step of forming the anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution,
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
Forming an upper electrode and a pixel electrode by patterning after forming an upper electrode material made of a transparent electrode film that is a transparent conductive oxide ,
A second heat treatment step performed in a vacuum after the step of forming the upper electrode and the pixel electrode. A lower electrode connected to the signal electrode, an anodic oxide film disposed on the lower electrode, an upper electrode overlapping the anodic oxide film, and a method for manufacturing a thin film diode including a pixel electrode connected to the upper electrode.
Anodizing treatment step of forming the anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution;
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
A second heat treatment step performed in an inert atmosphere or a reducing atmosphere after forming an upper electrode material made of a transparent electrode film that is a transparent conductive oxide;
Forming the upper electrode and the pixel electrode by patterning the upper electrode material after the second heat treatment step. An island-shaped lower electrode separated from the signal electrode; and a lower electrode formed on the surface of the lower electrode.
An anode oxide film to be formed, a first upper electrode and a second upper electrode formed so as to overlap the lower electrode via the anodic oxide film, and a pixel electrode connected to the second upper electrode. In a method of manufacturing a thin film diode,
Anodizing treatment step of forming an anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution;
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
A second heat treatment step performed in a vacuum after forming an upper electrode material made of a transparent electrode film that is a transparent conductive oxide;
Forming the first upper electrode, the second upper electrode, and the pixel electrode by patterning the upper electrode material after the second heat treatment step. Diode manufacturing method. An island-shaped lower electrode separated from the signal electrode; an anodic oxide film formed on the surface of the lower electrode; a first upper electrode and a second upper electrode formed to overlap the lower electrode via the anodic oxide film A method of manufacturing a thin-film diode comprising: a second upper electrode and a pixel electrode connected to the second upper electrode.
Anodizing treatment step of forming an anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution;
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
Forming an upper electrode material made of a transparent electrode film, which is a transparent conductive oxide, and then forming a pattern to form the first upper electrode, the second upper electrode, and the pixel electrode;
A method for manufacturing a thin-film diode, comprising: a second heat treatment step performed in a vacuum after the step of forming the first upper electrode, the second upper electrode, and the pixel electrode . An island-shaped lower electrode separated from the signal electrode; an anodic oxide film formed on the surface of the lower electrode; a first upper electrode and a second upper electrode formed to overlap the lower electrode via the anodic oxide film A method of manufacturing a thin-film diode comprising: a second upper electrode and a pixel electrode connected to the second upper electrode.
Anodizing treatment step of forming an anodized film on the surface of the lower electrode using ammonium borate, phosphoric acid or ammonium phosphate as an anodized solution;
A first heat treatment step performed in a vacuum after the formation of the anodic oxide film;
A second heat treatment step performed in an inert atmosphere or a reducing atmosphere after forming an upper electrode material made of a transparent electrode film that is a transparent conductive oxide;
Forming the first upper electrode, the second upper electrode, and the pixel electrode by patterning the upper electrode material after the second heat treatment step. Diode manufacturing method. 7. The method according to claim 1, wherein the lower electrode material is formed of a tantalum film, and a tantalum oxide film is formed as the anodic oxide film.

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