KR100352195B1 - Plasma display panel having a ferroelectric thin film and ferroelectric thin film evaqporation method - Google Patents

Abstract

The present invention relates to a method of depositing a plasma display panel (PDP) having a ferroelectric layer and a ferroelectric thin film on a substrate, the front and rear glass to be a substrate; An electrode part formed on each of one side of the front and rear glass; A ferroelectric thin film deposited on each of one side of the front and rear glass; Discharge cells composed of a protective film deposited on the ferroelectric thin film is characterized in that it provides a PDP having a structure separated from each other by a partition wall. The present invention uses a ferroelectric having a high transmittance and permittivity compared to a conventional PDP using a PbO-based glass paste dielectric, thereby maintaining the discharge light emission at a lower voltage, lowering the overall power consumption, and high transmittance (90%). Due to the above) and the dielectric constant, the amount of charge accumulation required for discharging is large, which may improve luminance.

Description

Plasma display panel with ferroelectric thin film and ferroelectric thin film deposition method {PLASMA DISPLAY PANEL HAVING A FERROELECTRIC THIN FILM AND FERROELECTRIC THIN FILM EVAQPORATION METHOD}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel (hereinafter referred to as PDP), and more particularly to a method of depositing a PDP having a ferroelectric layer and a ferroelectric thin film on a substrate.

Electronic display devices are very important devices that play a role of bridge for information exchange between humans and machines and humans through human eyes. Such electronic display devices are widely used in a variety of industrial and consumer fields today. The conventional electronic display device market is mainly a stationary Cathode Ray Tube (CRT) such as TV and computer monitor. However, these mounted display devices have disadvantages that cannot be carried, and there is a limit to expanding the display size in consideration of space utilization.

In order to solve this drawback, the light and simple flat panel display devices are liquid crystal display (LCD), plasma display panel (PDP), field emission display (FED), and electroluminescene (EL). Among the flat panel display devices described above, PDP has a large size and a thinness compared to LCD which has been expanding its market centering on portable products, and thus, it is expected to be a great substitute for CRT and a new large screen mount type product. The PDP is a device that uses light emission according to discharge, and the ultraviolet rays generated from the discharge in the micro discharge cell filled with a mixed gas of inert gases such as helium (He), neon (Ne), xenon (Xe), etc. It uses the principle of emitting light by stimulating fluorescent material.

On the other hand, PDP can be classified into AC type and DC type according to the operation power supply method. AC type PDP has lower luminance and higher initial investment cost, while the structure of device is simple, long life and low power consumption. Because of its merits, it is adopted by many companies such as NEC, Pioneer, Fujitsu and Hitachi.

Hereinafter, the role of the dielectric layer of the AC PDP will be described with reference to the drawings. First, FIG. 1 illustrates a cross-sectional view of a typical AC PDP discharge cell. The AC PDP includes an electrode 10 as shown in FIG. It is characteristic that the transparent dielectric layer 12 and the protective film 14 are wrapped. The transparent dielectric layer 12 should protect the electrode 10 from the ion bombardment of the plasma, and be able to maintain the discharge light emission at a voltage lower than the initial discharge start voltage by using the residual wall charges generated in the dielectric layer 12 after the start of discharge. do. For this purpose, the transparent dielectric should have characteristics that are transparent and have a high dielectric constant so that it can withstand a strong electric field, and crystal defects such as pinholes should not easily occur.

On the other hand, the charge accumulation amount Q that contributes to the discharge can be expressed by Equation 1 below.

In Equation 1, C denotes the capacitance of the discharge cell, V denotes the applied voltage, S denotes the charge area, and d and? Denote the thickness and dielectric constant of the dielectric layer 12, respectively. As shown in Equation 1, it is necessary to reduce the thickness of the dielectric layer 12 and increase the dielectric constant in order to reduce the applied power supply and decrease the dot pitch to decrease the charge area S.

However, the dielectric layer 12 used in the AC type PDP is a PbO-based glass paste. Since the dielectric constant is about 10, it is difficult to expect the improvement of characteristics due to the change of the applied voltage (V) and the charge area (S). . This is also a reason why the power consumption of the PDP can no longer be reduced. In the conventional PDP, a screen printing method is adopted as a method for producing a dielectric layer. However, when the dielectric layer is manufactured by using the conventional printing method, contamination by impurities in the air may occur when the dielectric layer is manufactured, and the thickness of the dielectric layer may vary as the printing coated dielectric layer shrinks during the firing process. There is a disadvantage.

Accordingly, an object of the present invention is to provide a plasma display panel (PDP) having a ferroelectric thin film capable of reducing power consumption due to PDP operation by maintaining discharge emission at a lower voltage, compared to conventional PDPs using PbO-based glass paste dielectrics. And ferroelectric thin film deposition method.

Another object of the present invention is to use a ferroelectric having a high transmittance and permittivity compared to a conventional PDP using a PbO-based glass paste dielectric, thereby improving brightness and having a ferroelectric thin film that can withstand a strong electric field. To provide a panel (PDP) and ferroelectric thin film deposition method.

Still another object of the present invention is to provide a ferroelectric thin film deposition method capable of uniformly manufacturing a dielectric layer.

Plasma display panel according to an embodiment of the present invention for achieving the above object;

Front and rear glass serving as a substrate; An electrode part formed on each of one side of the front and rear glass; A ferroelectric thin film deposited on each of one side of the front and rear glass; Discharge cells composed of a protective film deposited on the ferroelectric thin film is separated from each other by a partition wall.

In addition, the present invention for achieving the above object;

A first step of mounting the substrate on the substrate holder and maintaining the vacuum state of the reaction chamber in a high vacuum state;

A second step of raising the temperature of the substrate to a temperature suitable for thin film deposition and rotating the substrate at a predetermined speed;

Using a ultrasonic wave to make the ferroelectric precursor solution into a precursor mist state and transferring the ferroelectric precursor solution to the reaction chamber using an inert carrier gas;

And a fourth process of depositing a ferroelectric thin film on the substrate by co-injecting the precursor mist and a reactive gas for producing an oxide thin film into the reaction chamber.

1 is a cross-sectional view of a typical AC plasma display panel (PDP) discharge cell.

2 is a cross-sectional view of an AC type PDP front plate having a ferroelectric thin film according to an embodiment of the present invention.

3 is an exemplary view of a vacuum spray apparatus for depositing a ferroelectric thin film according to an embodiment of the present invention.

4 is a flowchart of a ferroelectric thin film deposition process for explaining a process of depositing a ferroelectric thin film on a substrate according to an embodiment of the present invention.

-Explanation of symbols for the main parts of the drawing-

10 electrode 12 dielectric

14: protective film 16a, 16b: front, rear glass

18: bulkhead 20: phosphor

22: address electrode 24: bus electrode

Hereinafter, a method of depositing a ferroelectric thin film on a substrate and a plasma display panel having a ferroelectric thin film according to an embodiment of the present invention will be described in detail.

2 illustrates a cross-sectional view of an AC PDP front plate having a ferroelectric thin film according to an embodiment of the present invention.

The discharge cell structure of the AC-type PDP according to the embodiment of the present invention is first composed of an electrode 10 and a bus electrode 24 by thick film printing or the like on one side of the front glass 16a serving as the substrate. Form wealth. The ferroelectric thin film is formed by depositing a ferroelectric thin film 30 having a perovskite structure having a relative dielectric constant of about 500 to 1000 and having excellent transmittance on the front glass 16a having the electrode portion by using a vacuum spray method. do. Examples of the ferroelectric having the perovskite structure include Lead Lanthanum Titanate (PLT) and Lead Lanthanum Zirconium Titanate (PLZT). On the ferroelectric thin film 30, a magnesium oxide layer (MgO) 14 as a protective film is deposited to about 200 nm. The rear glass side is subjected to the process in the same manner as described above. The difference is that the conductor on the front glass side and the ferroelectric layer need to be treated to be as transparent as possible. The reason is to maximize the brightness. On the other hand, the distance from the protective film surface on the front glass 16a side to the rear protective film surface is maintained by a gap ball or the like, while separating the discharge cells one by one, as shown in FIG. Barrier 18 is to be printed, and an inert gas is enclosed in the discharge cell made by the partition wall printing.

Hereinafter, an apparatus and a fabrication process of depositing a ferroelectric thin film on the front glass 16a having the electrode portion using the vacuum spray method will be described in detail.

First, Figure 3 illustrates a vacuum spray apparatus for depositing a ferroelectric thin film according to an embodiment of the present invention, Figure 4 is a ferroelectric thin film for explaining the process of depositing a ferroelectric thin film according to an embodiment of the present invention A deposition process flow diagram is shown.

In the embodiment of the present invention after manufacturing a sol-gel (sol-gel) solution to deposit a ferroelectric thin film on the substrate, the substrate can be manufactured in a vacuum environment by using a vacuum spray method compatible with the semiconductor process A method of depositing a uniform ferroelectric thin film on the substrate was adopted. The vacuum spray method is a method of depositing a thin film by spraying a liquid precursor solution in the form of a mist (mist) to the reaction chamber in a vacuum.

As shown in FIG. 3, the vacuum spraying method includes a reaction chamber 44 capable of accommodating a large area substrate 48, an apparatus capable of supplying a liquid ferroelectric precursor (not shown), and a liquid ferroelectric. It consists of an ultrasonic generator 40 for generating ultrasonic waves so that the precursor is sprayed in the form of mist. The precursor solution used in the production of the ferroelectric thin film is prepared by using the sol-gel method, and the amount of solution to be injected in total is controlled by using a syringe infusion pump, and all the mists are sprayed by ultrasonic waves at the spray nozzle. Is made with. The resulting mists are deposited on the heated substrate 48 through a shower head 42 installed in the reaction chamber 44 by an inert carrier gas Ar with a flow rate controlled. Sprayed in mist form. The carrier gas Ar is injected into the mixing chamber 38 through the pipe 34, and the ferroelectric precursor solution is injected into the mixing chamber 38 through the pipe 32. And oxygen gas (reactive gas) ) Is injected into the reaction chamber 44 through the pipe 36 and the shower head 42.

Ferroelectric precursor mist injected into the reaction chamber 44 is oxidized gas ( Pyrolysates on the substrate 48 positioned on the substrate holder 46 to be deposited as a ferroelectric thin film. At this time, crystal growth is possible with ferroelectric on the substrate 48, and the substrate holder 46 is heated by using a halogen lamp to produce a thin film of dense and uniform surface. The temperature at which the homogeneous thin film is formed does not generally coincide with the temperature at which the ferroelectric phase is formed, thereby making it possible to control the temperature of the substrate holder 46. In addition, the deposition process is performed while rotating the substrate 48 to obtain a uniform surface structure of the ferroelectric thin film.

Hereinafter, a detailed description will be given of the above-described schematic process of depositing a ferroelectric thin film. First, in step 50, a substrate 48 to be deposited is mounted on a substrate holder 46 in a reaction chamber 44. The vacuum degree of the reaction chamber 44 is high vacuum ( Hold vacuum until Torr). When the desired vacuum reaches a high vacuum base pressure, in step 52 the temperature of the substrate 48 is increased to a temperature suitable for thin film deposition (600-650 ° C.). At this time, considering the change of vacuum degree according to the temperature rise, maintain the current process for about 30 minutes after reaching the set temperature. Thereafter, in step 54, the substrate 48 is rotated at a speed of ˜200 RPM to maintain uniformity of the deposited thin film.

Meanwhile, in step 56, the amount of the precursor solution to be injected is adjusted by using a syringe infusion pump, and then injected into the mixing chamber 38 through the pipe 32, and the injected precursor solution is an ultrasonic generator ( It is made into the mist state by the ultrasonic wave generated in 40) and is conveyed to the reaction chamber 44 by an inert carrier gas Ar whose flow rate is controlled by an MFC (mess flow controller). At the same time, oxygen gas as a reactive gas for producing an oxide thin film is controlled by MFC according to the process conditions and transported to the reaction chamber 44 (step 58). In operation 60, the valve connected to the reaction chamber 44 is opened to inject the mist and the oxidizing gas of each precursor into the reaction chamber 44 to start thin film deposition of the ferroelectric. The thin film deposition process is continued until the thin film reaches the desired thickness. After the deposition process is completed, in step 62, the temperature of the substrate 48 is reduced to room temperature, and the vacuum degree of the reaction chamber 44 is maintained at the above-described basic pressure. In step 64, the deposition of the ferroelectric thin film is completed by separating the substrate 48 from the substrate holder 46 in the reaction chamber 44.

Therefore, the ferroelectric thin film having a uniform surface structure can be deposited on the front glass or the rear glass substrate on which the electrode portion 24 is printed by the above-described process.

As described above, the present invention uses a ferroelectric having a high transmittance and permittivity compared to a conventional PDP using a PbO-based glass paste dielectric, thereby maintaining the discharge light emission at a lower voltage and lowering the overall power consumption. In addition, due to the high transmittance (90% or more) and the dielectric constant, the amount of charge accumulation required for discharging is large, which has the advantage of improving luminance. In addition, it can withstand a strong electric field has the advantage of extending the life of the discharge cell.

Claims (7)

delete delete delete In a method for depositing a ferroelectric thin film on a substrate, A first step of mounting the substrate on the substrate holder and maintaining the vacuum state of the reaction chamber in a high vacuum state; A second step of raising the temperature of the substrate to 600 to 650 ° C. suitable for thin film deposition and rotating the substrate at a speed of 200 RPM or less; A third step of making the ferroelectric precursor solution having a perovskite structure by using ultrasonic waves in a precursor mist state and transporting the ferroelectric precursor solution to the reaction chamber using an inert carrier gas; And a fourth process of depositing a ferroelectric thin film on the substrate by injecting oxygen (O ₂ ) gas into the reaction chamber as a reactive gas for producing the precursor mist and the oxide thin film. . 5. The method of claim 4, wherein the ferroelectric precursor solution is made of a sol-gel type solution. delete delete