JP2004029386A - Display panel and manufacturing method thereof - Google Patents

Abstract

A display panel having a uniform narrow cell gap is provided.
A liquid crystal panel includes a substrate having electrodes, a counter substrate facing the substrate, an insulating spacer formed on the electrodes and containing a zinc compound (for example, ZnS), and a substrate. And a liquid crystal layer 7 interposed in a gap between the first substrate 200 and the opposite substrate 200. Since the insulating spacer 6 can be formed from a ZnS film that can be easily patterned with hydrochloric acid, the controllability of the cell gap is excellent.
[Selection diagram] Fig. 1

Description

【００３６】
【発明の効果】
本発明の表示パネルによれば、セル厚１μｍ〜２μｍ程度の均一な狭セルギャップを得ることができる。本発明の表示パネルの製造方法によれば、透明ＩＴＯ電極やガラス基板を傷めることなく良好なエッチングが可能となり、絶縁性スペーサを設置位置の制限なく任意の位置に形成することができる。
【図面の簡単な説明】
【図１】実施形態１の液晶パネルを模式的に示す断面図である。
【図２】実施形態１の液晶パネルを模式的に示す平面図である。
【図３】実施形態１におけるＣＦ基板１００の製造工程を示す断面図である。
【図４】実施形態２の液晶パネルを模式的に示す断面図である。
【図５】実施形態２におけるＣＦ基板１００の製造工程を示す断面図である。
【図６】一般的な液晶パネルを模式的に示す断面図である。
【符号の説明】
１　ガラス基板
２　ブラックマトリクス
３　カラーフィルタ（ＣＦ）
４　ＩＴＯ電極（共通電極）
５　ポリイミド膜
６　絶縁性スペーサ（ＺｎＳ薄膜スペーサ）
７　液晶層
８　ポリイミド膜
９　画素電極
１０　第３絶縁層
１１　ソースバスライン
１２　第２絶縁層
１３　Ｃｓライン
１４　第１絶縁層
２１　コンタクトホール
２２　　コンタクトホール
２３　　蓄積容量（Ｃｓ）
２４　　ＴＦＴ素子
２５　ゲートバスライン
３１　ＺｎＳ膜
３２　フォトレジスト
３３　ＺｎＯ膜
３４　ＺｎＯ層
３５　ＺｎＳ層
１００　ＣＦ基板
２００　ＴＦＴ基板[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a display panel used as a flat panel display and a method for manufacturing the same.
[0002]
[Prior art]
With the development of portable telephones and the development of portable information terminals generally called PDAs (Personal Digital Assistance) and electronic books, demand for medium-sized and small-sized high-speed response liquid crystal panels is increasing. FIG. 6 is a cross-sectional view schematically showing a general liquid crystal panel. The liquid crystal panel is configured by sandwiching a liquid crystal layer 7 between a pair of substrates 1 and 16. In order to keep the thickness of the liquid crystal layer 7, that is, the cell gap constant, spherical plastic beads 17 are dispersed between the pair of substrates 1 and 16.
[0003]
[Problems to be solved by the invention]
On the other hand, in order to realize a high-speed response liquid crystal panel, it is necessary to realize a cell gap of 1 μm to 2 μm. However, the particle diameter of general plastic beads is about 3 μm to 5 μm, and it is difficult to obtain plastic beads of 1 μm to 2 μm. Even if it can be obtained, it is difficult to control the cell gap because the diameter distribution is ± 0.2 μm or more.
[0004]
Instead of spraying the spherical plastic beads 17, there is also a technique in which a resist is applied on a substrate and patterned in a columnar shape to form a columnar spacer. However, since the thickness distribution of the resist coating is about ± 0.2 μm, this method also makes it difficult to control the cell gap to 2 μm or less.
[0005]
An object of the present invention is to provide a display panel having a uniform narrow cell gap.
[0006]
[Means for Solving the Problems]
The display panel of the present invention includes a substrate having electrodes, a counter substrate facing the substrate, an insulating spacer containing a zinc compound formed on the electrodes, and interposed in a gap between the substrate and the counter substrate. And a display medium layer. Since the insulating spacer containing a zinc compound can be formed by vapor deposition, the film thickness controllability is very good, and precise cell thickness control of the liquid crystal panel can be realized. Further, as described later, the zinc compound film formed by vapor deposition has an advantage at the time of etching. Here, the “display medium layer” is a layer whose light transmittance is modulated by a potential difference between electrodes facing each other, or a layer which emits light by current flowing between the electrodes facing each other. The display medium layer is, for example, a liquid crystal layer, an inorganic or organic electroluminescence (EL) layer, a luminescent gas layer, an electrophoretic layer, an electrochromic layer, or the like.
[0007]
The zinc compound is preferably zinc sulfide. Since zinc sulfide has an insulating property of a dielectric breakdown voltage of 1 MV / cm, the electrical insulating property between the two substrates is maintained, and the problem of leakage does not occur.
[0008]
The insulating spacer preferably has a layer made of zinc oxide between the insulating spacer and the electrode. When the electrode is made of an oxide such as indium tin oxide (hereinafter referred to as ITO), the adhesion between the sulfide of the different element and the oxide is not so good. By forming a ZnO film between an electrode of an oxide such as ITO and a film of a zinc compound such as ZnS, adhesion between the electrode and the zinc compound film can be maintained while maintaining insulation and easy etching. Properties can be further improved.
[0009]
It is preferable that the insulating spacer is formed in a region of the storage capacitor. In the case of a transmissive liquid crystal panel, the area of the storage capacitor is a light-shielding area, so that a decrease in aperture ratio due to the formation of the insulating spacer can be suppressed. Further, the region of the storage capacitor has an appropriate area for forming the spacer, and has good planarity, so that it is suitable for forming the spacer.
[0010]
The method of manufacturing a display panel according to the present invention includes the steps of: forming an insulating film containing a zinc compound on the electrode; forming a resist having a desired pattern on the insulating film; Etching with an etching solution containing hydrochloric acid as a main component.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a liquid crystal panel will be described as an example, but the display panel of the present invention may be any of various types such as an organic EL panel, an inorganic EL panel, a plasma display panel (PDP), a vacuum fluorescent display (VFD) panel, and electronic paper. It is also applicable to a display panel.
[0012]
Further, a transmissive liquid crystal panel driven by a TFT (Thin Film Transistor) will be described as a liquid crystal panel, but the display panel of the present invention is not limited to this. Display panels using active elements other than TFTs, for example, other three-terminal elements such as FET (Field Effect Transistor), and display panels using two-terminal elements such as MIM (Metal Insulator Metal) and TFD (thin film diode). Can be applied. The present invention can be applied to not only an active drive type display panel but also a passive (multiplex) drive type STN (Super Twisted Nematic) display panel. Further, not only a transmission type but also a reflection type or a reflection / transmission type display panel is possible.
[0013]
(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing the liquid crystal panel of Embodiment 1, and FIG. 2 is a plan view. The liquid crystal panel of the present embodiment includes a CF substrate 100 on which a color filter (hereinafter, referred to as CF) is formed, a TFT substrate (opposite substrate) 200 facing the CF substrate 100, and a gap between the CF substrate 100 and the TFT substrate 200. And a TN (Twisted Nematic) liquid crystal layer 7 interposed therebetween.
[0014]
The TFT substrate 200 includes a silicon (Si) layer 15, a first insulating layer 14, a gate bus line 25, a storage capacitor line (Cs line) 13, a second insulating layer 12, a source bus line 11, It is configured by forming three insulating layers 10, a pixel electrode 9 made of ITO, and a polyimide film 8. Note that, instead of the glass substrate 16, another insulating substrate such as a plastic substrate may be used.
[0015]
Specifically, a plurality of gate bus lines 25 substantially parallel to each other extend in the column direction on the glass substrate 16. In a direction substantially orthogonal to the plurality of gate bus lines 25, that is, in a row direction, the plurality of source bus lines 11 substantially parallel to each other intersect with the plurality of gate bus lines 25 via the second insulating layer 12, Extending. A coplanar type TFT element 24 is formed near each intersection of the plurality of gate bus lines 25 and the plurality of source bus lines 11. The TFT element 24 connects the source bus line 11 and the silicon layer 15 via the silicon layer 15, a gate electrode extending in the row direction from the gate bus line 25, and a contact hole 21 penetrating the first insulating layer 14. It has a source electrode and a drain electrode. A plurality of pixel electrodes 9 are arranged in a matrix in a region surrounded by the plurality of gate bus lines 25 and the plurality of source bus lines 11. The pixel electrode 9 is connected to a drain electrode of the TFT element 24 via a contact hole 22 penetrating the first insulating layer 14 and the second insulating layer 12.
[0016]
A storage capacitor line 13 is formed on the silicon layer 15 via a first insulating layer 14, and a storage capacitor (storage capacitor) 23 is provided between the storage capacitor line (Cs line) 13 and the pixel electrode 9. It is formed. The storage capacitance line 13 is usually formed from the same film as the gate bus line 25. Since a metal such as Ta (tantalum) is used as a material of the gate bus line 25 and the storage capacitor line 13, the region of the storage capacitor 13 is a light shielding region. A polyimide film 8 is formed on the pixel electrode 9, and a rubbing process is performed on the polyimide film 8 to control the alignment of liquid crystal molecules.
[0017]
The CF substrate 100 is formed by forming a CF 3, an ITO film 4, an insulating spacer 6 and a polyimide film 5 on a glass substrate 1. Note that, instead of the glass substrate 16, another insulating substrate such as a plastic substrate may be used.
[0018]
Specifically, the black matrix 4 is formed in a region on the glass substrate 1 that overlaps with the gate bus line 25, the source bus line 11, and the TFT element 24. Red, green, and blue CFs 3a, 3b, and 3c are formed in stripes, and a transparent ITO film (ITO electrode) 4 is formed on the entire surface of CF3. A cylindrical insulating spacer 6 is formed on the ITO electrode 4. The insulating spacer 6 is formed in a region of the storage capacitor 9 formed for each pixel. Strictly speaking, the insulating spacer 6 is formed in a region on the ITO electrode 4 that overlaps the storage capacitor 9. Further, a polyimide film 5 is formed on the ITO electrode 4, and a rubbing process is performed on the polyimide film 8 in order to control alignment of liquid crystal molecules.
[0019]
In the present embodiment, the insulating spacer 6 is formed in the region of the storage capacitor 9, but the insulating spacer 6 is basically arranged in any region as long as the region maintains planarity. You may. However, due to the optical characteristics, it is not preferable to dispose them in the effective driving area of the pixel. In the case of a transmissive liquid crystal panel, the area of the storage capacitor 13 is a light-shielding area. Therefore, as in the present embodiment, the insulating spacer 6 is formed in the area of the storage capacitor 13 to suppress a decrease in the aperture ratio. Can be. Further, the region of the storage capacitor has a suitable area for forming the spacer 6 and has good planarity, so that it is suitable for forming the spacer 6. The spacer 6 preferably has a diameter of about 10 μm to 20 μm, one for each pixel, depending on the pixel area. By disposing the spacer 6 in the storage capacitor region of each pixel, it is possible to obtain a liquid crystal panel having a narrow cell gap and a more stable cell thickness distribution.
[0020]
In the present specification, three pixels of red, green, and blue constitute one picture element. In the present embodiment, the pixel electrode 9 and the ITO electrode (common electrode) 4 facing the pixel electrode 9 define a pixel. In a simple matrix type liquid crystal panel, each region where a column electrode provided in a stripe shape and a row electrode provided orthogonal to the column electrode cross each other defines a pixel. Strictly speaking, of the regions to which the voltage is applied according to the state to be displayed, the region corresponding to the opening of the black matrix 2 corresponds to the pixel.
[0021]
The insulating spacer 6 contains a zinc compound such as zinc sulfide or zinc oxide. Since the insulating spacer 6 containing the zinc compound can be formed by vapor deposition, the film thickness controllability is very good, and precise cell thickness control of the liquid crystal panel can be realized. The insulating spacer 6 is in physical contact with the pixel electrode 9 via the polyimide film 8. However, in the case of the insulating spacer 6 made of, for example, zinc sulfide, the insulating spacer 6 has a sufficiently large dielectric breakdown voltage (1 MV / cm), and is therefore electrically insulated, and does not cause a leakage problem. . For example, a 1 μm thick ZnS thin film spacer 6 has a withstand voltage characteristic of 100 V and 200 V at 2 μm. Since the applied voltage of the TFT or TFD used in the liquid crystal panel is about 10 V to 30 V, the withstand voltage characteristics of the ZnS thin film spacer 6 are sufficient.
[0022]
Next, a method for manufacturing the liquid crystal panel of the present embodiment will be described. On the TFT substrate 16, the gate bus line 25, the storage capacitor line 13, the source bus line 11, the TFT element 24, the pixel electrode 9, and the like are formed by a photolithography method, the polyimide film 8 is formed by a printing method, and a rubbing process is performed. Can be produced by
[0023]
The manufacturing process of the CF substrate 100 will be described with reference to FIG. First, CF3 is formed on the glass substrate 1 by a printing method or the like, and the ITO electrode 4 is formed on the CF3 by mask evaporation (see FIG. 3A). A ZnS film 31 is deposited on the ITO electrode 4 (see FIG. 3B). The ZnS film 31 is formed at a substrate temperature of about 200 ° C. by electron beam evaporation. The ZnS film 31 has a thickness of about 1 μm or more and 2 μm or less. Thereafter, a photoresist 32 having a desired pattern, generally a circular pattern, is formed (see FIG. 3C). The exposed ZnS film 31 is etched with hydrochloric acid or an etching solution containing hydrochloric acid as a main component (see FIG. 3D). The photoresist 32 is stripped with a stripping solution to obtain a columnar insulating spacer 6 (see FIG. 3E).
[0024]
About 37% of hydrochloric acid used for etching is used. The etching solution containing hydrochloric acid as a main component is obtained by diluting about 37% hydrochloric acid with water, and may further contain acetic acid or the like. In the case of the ZnS thin film 31 having a thickness of 1 μm, etching can be performed in about 120 seconds with a diluted etching solution of hydrochloric acid: water = 1: 1.
[0025]
As in the present invention, a technique for producing a spacer from a thin film is disclosed in, for example, JP-A-2-234120 and JP-A-8-248428. In the methods disclosed in these publications, since the film is formed using vacuum evaporation or sputtering, the height of the spacer can be determined with an accuracy of less than ± 0.05 μm, and the cell gap can be accurately controlled. An SiO ₂ film or a SiN _x film is used as the thin film, and an etching solution such as hydrofluoric acid is used for the etching.
[0026]
However, since hydrofluoric acid dissolves the glass, the glass substrate is damaged when a SiO ₂ film or the like is formed and etched on the glass substrate. Further, since ITO is also dissolved in hydrofluoric acid, the ITO electrode is also damaged when a SiO ₂ film or the like is formed on the ITO electrode and etched. Therefore, the position where the spacer is formed must be limited, or some measure such as forming a protective film on the glass substrate or the ITO electrode is required.
[0027]
In this embodiment, hydrochloric acid that hardly dissolves glass or ITO is used for etching, so that the glass substrate 1 and the ITO electrode 4 are hardly etched by hydrochloric acid. Therefore, the glass substrate 1 and the ITO electrode 4 are not damaged, and the installation position of the insulating spacer 6 can be freely set.
[0028]
After a polyimide resin is applied to the CF substrate 100 and the TFT substrate 200 to form the polyimide films 5 and 8, a rubbing process is performed. A seal material is screen-printed on the periphery of one of the substrates, and the pair of substrates 1 and 16 are bonded via the seal material. In the present invention, it is not necessary to spray the plastic beads. After that, the bonded substrate is divided, a liquid crystal material is injected from an opening of the sealant, and a liquid crystal panel is obtained through a step of sealing the opening.
[0029]
(Embodiment 2)
FIG. 4 is a cross-sectional view schematically illustrating the liquid crystal panel of the second embodiment. In the following drawings, components having substantially the same functions as the components of the liquid crystal panel of Embodiment 1 are denoted by the same reference numerals, and description thereof is omitted.
[0030]
The liquid crystal panel according to the first embodiment is different from the liquid crystal panel according to the first embodiment in that the insulating spacer 6 is formed from a stacked film of the ZnS thin film 31 and the ZnO film 33. Different from panel. Depending on the height and diameter of the insulating spacer 6, the adhesion between the ITO electrode 4 and the ZnS film 31 may become a problem. In this case, a ZnO film 33 as an adhesion layer having a thickness of about 30 nm to 300 nm can be formed between the ITO electrode 4 and the ZnS film 31 to improve the adhesion.
[0031]
The manufacturing process of the CF substrate 100 according to the present embodiment will be described with reference to FIG. First, as in the first embodiment, CF3 is formed on the glass substrate 1, and the ITO electrode 4 is formed on the CF3 (see FIG. 5A). A ZnO film 33 and a ZnS film 31 are sequentially deposited on the ITO electrode 4 (see FIG. 5B). The ZnO film 33 is formed by electron beam evaporation at a substrate temperature of about 150 ° C., and the ZnS film 31 is formed by electron beam evaporation at a substrate temperature of about 200 ° C. Thereafter, similarly to the first embodiment, a photoresist 32 having a circular pattern is formed (see FIG. 5C), and the exposed ZnS film 31 and ZnO film are exposed using hydrochloric acid or an etching solution containing hydrochloric acid as a main component. 33 is etched (see FIG. 5D). The ZnO film 34 is also soluble in an etchant containing hydrochloric acid as a main component, and can perform good etching. The photoresist 32 is stripped with a stripping solution to obtain a columnar insulating spacer 6 (see FIG. 5E). In the present embodiment, the insulating spacer 6 includes a ZnO layer 34 and a ZnS layer 35.
[0032]
(Other embodiments)
In the first and second embodiments, the insulating spacer 6 is formed on the ITO electrode 4 of the CF substrate 100. However, the insulating spacer 6 may be formed on the pixel electrode 9 of the TFT substrate 200. Further, in Embodiments 1 and 2, the shape of the insulating spacer 6 is cylindrical, but is not limited to this. The cross-sectional shape of the spacer 6 cut along a plane parallel to the substrate surface may be a square, a triangle, a polygon, or the like, in addition to a circle. The cross-sectional shape of the spacer 6 cut along a plane perpendicular to the substrate surface may be a trapezoidal shape or an inverted trapezoidal shape having a controlled taper shape, in addition to a square shape. The spacer 6 may have a wall shape instead of a column shape.
[0033]
Since the display panel of the present invention can realize a uniform narrow cell gap of 1 μm to 2 μm, when the present invention is applied to a liquid crystal panel, a high-speed response display is possible, and the color distribution in the cell is reduced. Be improved. Therefore, the liquid crystal panel to which the present invention is applied can be suitably used for a mobile phone supporting a moving image and a high-speed response liquid crystal television.
[0034]
(Example)
The display panel of Embodiment 1 was manufactured. A 2-inch diagonal transmissive liquid crystal panel having pixels of 320 × RGB × 240 pixels and a pixel size of 45 μm × 135 μm was produced. The ZnS thin film spacer 6 having a diameter of 10 μm and a height of 1.2 μm was provided so as to be located in the region of the storage capacitor 23 of all pixels. Table 1 shows data of the average value and the variation of the diameter and height of the spacer 6 and the cell gap. Nine points were measured in each panel surface for ten panels. The reason why the cell gap is larger than the spacer height by 0.3 μm is that the spacer 6 is arranged in the region of the storage capacitor 23 having a smaller cell gap than other pixel regions. As shown in Table 1, a uniform narrow cell gap of 1.5 ± 0.08 μm was obtained.
[0035]
[Table 1]

[0036]
【The invention's effect】
According to the display panel of the present invention, a uniform narrow cell gap having a cell thickness of about 1 μm to 2 μm can be obtained. ADVANTAGE OF THE INVENTION According to the manufacturing method of the display panel of this invention, a favorable etching is attained, without damaging a transparent ITO electrode and a glass substrate, and an insulating spacer can be formed in arbitrary positions without restriction | limiting of an installation position.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically illustrating a liquid crystal panel according to a first embodiment.
FIG. 2 is a plan view schematically showing the liquid crystal panel of the first embodiment.
FIG. 3 is a cross-sectional view illustrating a manufacturing process of the CF substrate 100 according to the first embodiment.
FIG. 4 is a cross-sectional view schematically illustrating a liquid crystal panel according to a second embodiment.
FIG. 5 is a cross-sectional view illustrating a manufacturing process of the CF substrate 100 according to the second embodiment.
FIG. 6 is a cross-sectional view schematically showing a general liquid crystal panel.
[Explanation of symbols]
1 Glass substrate 2 Black matrix 3 Color filter (CF)
4 ITO electrode (common electrode)
5 Polyimide film 6 Insulating spacer (ZnS thin film spacer)
7 Liquid crystal layer 8 Polyimide film 9 Pixel electrode 10 Third insulating layer 11 Source bus line 12 Second insulating layer 13 Cs line 14 First insulating layer 21 Contact hole 22 Contact hole 23 Storage capacitance (Cs)
24 TFT device 25 Gate bus line 31 ZnS film 32 Photoresist 33 ZnO film 34 ZnO layer 35 ZnS layer 100 CF substrate 200 TFT substrate

Claims (5)

A substrate having electrodes, a counter substrate facing the substrate, an insulating spacer containing a zinc compound formed on the electrodes, and a display medium layer interposed in a gap between the substrate and the counter substrate. Display panel. The display panel according to claim 1, wherein the zinc compound is zinc sulfide. The display panel according to claim 1, further comprising a layer made of zinc oxide between the electrode and the electrode. The display panel according to claim 1, wherein the insulating spacer is formed in a region of a storage capacitor. A method for manufacturing a display panel according to claim 1,
Forming an insulating film containing a zinc compound on the electrode;
Forming a resist having a desired pattern on the insulating film;
Etching with a hydrochloric acid or an etching solution containing hydrochloric acid as a main component.

Images