WO2009154130A1 - Method for manufacturing plasma display panel and film forming apparatus - Google Patents

Abstract

The properties of a protective film can be stabilized.  In evaporating a metal oxide while transferring an object to be film-formed, while introducing oxygen and water in a larger amount than the amount of oxygen into a vacuum chamber, a metal oxide is evaporated so that the static film formation rate is not less than 40 nm/sec.  The luminescence intensity is measured at the time of evaporating the metal oxide and the measured result is feed backed to the output of a heating device (an electron gun 41).  The luminescence intensity is involved directly in film properties such as (111) intensity, and, thus protective films having good film properties such as crystal alignment, film density and optical properties can be stably formed.

Description

Plasma display panel manufacturing method and film forming apparatus

The present invention relates to a plasma display panel, and more particularly to a technique for forming an MgO film suitable as a protective film for a panel used in a PDP display device.

Conventionally, a plasma display panel (PDP) has been widely used in the field of display devices, and recently, a high-quality and low-cost PDP with a large screen is required.
Currently, the PDP is mainly a three-electrode surface discharge type in which a front plate having a sustain electrode and a scan electrode formed on a glass substrate and a back plate having an address electrode formed on the glass substrate are bonded together.

A discharge gas is enclosed between the front plate and the back plate. When a voltage is applied between the scan electrode and the address electrode to generate a discharge, the enclosed discharge gas is turned into plasma and ultraviolet rays are emitted. If the phosphor is arranged at a position where the emitted ultraviolet rays are irradiated, the phosphor is excited by the ultraviolet rays and visible light is emitted.
In general, a dielectric film is formed on the sustain electrode and the scan electrode, and a metal oxide film such as MgO or SrO is formed thereon for the purpose of protecting the dielectric and emitting secondary electrons. .

When an AC voltage is applied to the scan electrode and the sustain electrode to maintain the discharge, cations generated by the plasma of the discharge gas enter the scan electrode side and the sustain electrode side. The dielectric film is protected from cations by a protective film.

Also, Ca, Al, Si, Mn, Eu, Ti, water, hydrogen, etc. are added to the MgO-based protective film in order to improve luminous efficiency, discharge delay, and γ (secondary electron yield). Attempts have been made. (For example, Non-Patent Document 1)
Proc. 43rd PDP Technical Discussion Meeting, July 5, 2006, p32-p52 JP 2007-107092 A JP 2007-119831 A JP 2006-149833 A

It is said that the protective film containing MgO is more likely to emit secondary electrons as the peak intensity of (111) orientation is higher, and that the higher the refractive index, the denser and the higher the sputtering resistance. In general, the following characteristics are required.
(1) The crystal orientation is (111), and the peak intensity in XRD (X Ray Diffraction, X-ray diffraction) is 1500 cps (counts per second) or more.
(2) The filling rate (film density) is 82% or more (the refractive index is about 1.6 or more).

It is desirable that all of the above characteristics (1) and (2) are satisfied, the peak intensity is high, and the filling rate is high. However, the film density tends to decrease under the film forming conditions for improving the crystal orientation. Under the film forming conditions for increasing the film density, the crystal orientation tends to decrease.
That is, the film forming conditions for improving the above characteristics are contradictory. Therefore, when creating a protective film for PDP having more excellent characteristics than the current situation, it is necessary to make a film forming condition that emphasizes one of the characteristics, or to create an intermediate protective film having both characteristics. Absent.

The film formation conditions generally include the substrate temperature, pressure, oxygen, Ar, hydrogen, water and other process gas introduction amounts, gas partial pressure, and the like during film formation. These film formation conditions can be monitored and controlled. However, changing any film formation condition is insufficient for controlling the crystallinity of MgO and controlling necessary film characteristics.

When a metal oxide such as MgO, SrO, or CaO is irradiated with an electron beam and heated at a high temperature, a vapor of the metal oxide is generated, a part of the metal oxide is reduced, and the metal is dissociated. For example, in the case of magnesium oxide (MgO), a reaction (2MgO → 2Mg + O ₂ ) occurs when Mg is dissociated when irradiated with an electron beam.

If water is introduced when evaporating the metal oxide, water is decomposed by the electron beam and hydrogen as a reducing agent is generated. Therefore, the reduction reaction of the metal oxide (MgO + H ₂ → Mg + H ₂ O) is performed at a lower temperature. The amount of reduction increases even if the electron beam power is the same.
If oxygen or water is present when the electron beam is irradiated, the dissociated metal reacts with oxygen and water to become a metal oxide again (Mg + O ₂ → 2MgO, Mg + H ₂ O → MgO + H ₂ ).

Rather than forming a protective film with vapor of metal oxide that has evaporated without dissociating, the present inventors have mixed oxide into the protective film once the metal oxide has been dissociated and then oxidized. It has been found that the (111) crystal orientation of the protective film and the film density are higher when the film is formed.
As a result of further studies by the present inventors, in order to dissociate the metal oxide, water was introduced into the vacuum chamber and the electron beam was irradiated so that the film formation rate was 40 nm / second or more. I knew that I should do it.

When the metal is oxidized to a low energy state (oxide), light of a specific wavelength is emitted. For example, emission light when Mg is oxidized has characteristic peaks at wavelengths of 285.2 nm and 280.2 nm, and emission light when Sr is oxidized at wavelengths of 242.8 nm and 256.9 nm. There is a characteristic peak.

The peak size (intensity) of these specific wavelengths increases as the amount of oxidized metal increases, so if the emission intensity at a specific wavelength is measured, how much the metal oxide is dissociated and re-oxidized? Thus, it can be seen whether the film formation speed and the atmosphere including the electron beam are sufficient to dissociate the metal oxide and oxidize it again.

The present invention based on such knowledge, while introducing oxygen into the vacuum chamber, heats the metal oxide disposed in the evaporation source to generate the vapor of the metal oxide, the electrode on the surface The arranged first panel was transported through a transport path in the vacuum chamber, passed through a film forming position facing the evaporation source, and a protective film made of a metal oxide thin film was formed on the electrode. Thereafter, the first panel is bonded to the second panel, and the plasma display panel is manufactured by manufacturing the plasma display panel in which the protective film is exposed to plasma. Of the protective film when the first panel is stationary at the deposition position while introducing water so that the introduction volume of oxygen is equal to or greater than the introduction volume of oxygen per unit time. Deposition rate is 40n / While evaporating the metal oxide so that the second or higher, a method of manufacturing a plasma display panel for carrying the said first panel.
According to the present invention, a first panel having an electrode disposed on a surface thereof is disposed at a film forming position facing an evaporation source inside a vacuum chamber, and oxygen is introduced into the vacuum chamber while being disposed at the evaporation source. The metal oxide is heated to generate a vapor of the metal oxide, and a protective film made of a thin film of metal oxide is formed on the electrode of the first panel. A plasma display panel manufacturing method for manufacturing a plasma display panel in which a protective panel is exposed to plasma, wherein the volume of introduction per unit time of the oxygen is A plasma display that evaporates the metal oxide while introducing water so that the deposition rate of the protective film is 40 nm / second or more while introducing water so as to be equal to or larger than the introduced volume per unit time. Pa It is a manufacturing method of Le.
The present invention relates to a method for manufacturing a plasma display panel, wherein the metal oxide is irradiated with an electron beam to evaporate.
The present invention is a method for manufacturing a plasma display panel, wherein the total pressure of the vacuum chamber is set to a pressure exceeding 1 × 10 ⁻¹ Pa to generate the vapor of the metal oxide. .
The present invention is a method for manufacturing a plasma display panel, wherein the metal oxide is MgO.
The present invention is a method for manufacturing a plasma display panel, wherein the metal oxide contains MgO, and one or both of SrO and CaO are added.
The present invention is a method for manufacturing a plasma display panel, wherein when the metal oxide is evaporated, the emission intensity of light emitted into the vacuum chamber is measured, and the measured value of the emission intensity is preset. This is a method for manufacturing a plasma display panel in which the output of the heating device for evaporating the metal oxide is changed so as to have a value.
The present invention is a method for manufacturing a plasma display panel, wherein when the metal oxide is evaporated, the emission intensity of light emitted into the vacuum chamber is measured, and the measured value of the emission intensity is preset. This is a method of manufacturing a plasma display panel in which the irradiation area of the electron beam is changed so as to have a value.
The present invention includes a vacuum chamber, an evaporation source disposed in the vacuum chamber, a heating device for heating a vapor deposition material disposed in the evaporation source, a water inlet for introducing water into the vacuum chamber, An apparatus for forming a protective film having an oxygen inlet for introducing oxygen into the vacuum chamber, the measuring device for measuring the emission intensity of light generated inside the vacuum chamber, the measuring device, and the heating device The control device is a film forming device configured to change the output of the heating device based on the emission intensity transmitted from the measurement device.
The present invention is a film forming apparatus, wherein the heating device is an electron gun, and the control device is a film forming apparatus that changes an irradiation area of an electron beam emitted from the electron gun.
The present invention is a film forming apparatus, and includes a transfer device that transfers a film formation target along a transfer path inside the vacuum chamber, and the evaporation source is moved while moving along the transfer path. The water introduction port is a film forming apparatus that is closer to the evaporation source than the oxygen introduction port and farther from the transfer path.
The present invention is a film forming apparatus, comprising a substrate holder that holds a substrate at a position facing the evaporation source inside the vacuum chamber, wherein the water introduction port is closer to the evaporation source than the oxygen introduction port In addition, the film forming apparatus is located far from the substrate held by the substrate holder.

The present invention is configured as described above, and the protective film to be formed has good crystal orientation and high film density. When the crystal orientation is good, the (111) peak intensity of the protective film becomes high, and when the film density is high, the sputtering resistance is improved and the film thickness of the protective film can be reduced. For example, if the (111) peak intensity is 40% higher and the film density is high, the required film thickness can be reduced by 20% to 50%.

In order to reliably oxidize the dissociated metal, the amount of water introduced is the same as or larger than that of oxygen.
The amount of water and oxygen introduced may be defined by the partial pressure in the vacuum chamber, but since water is decomposed by an electron beam, it is difficult to accurately measure the partial pressure of water. Therefore, in the present invention, instead of the partial pressure, the introduction amount of water and oxygen is defined by the introduction volume (sccm) per unit time.

Since the crystal orientation is good, the secondary electron emission property of the protective film is high. Spatter resistance of the protective film is good due to high filling rate (film density), secondary electron emission is high, and sputter resistance of the protective film is good, so not only the life of the PDP is long, but also the film thickness can be reduced. Yes, PDP can be made thin. Thinning saves vapor deposition materials and reduces panel costs. Since the film formation rate is faster than the conventional one, not only the manufacturing time of the PDP is shortened, but also the possibility that impurities such as CO and CO ₂ are mixed is reduced. By monitoring the emission wavelength and feeding back to the power of the electron gun, the MgO film quality can be stabilized.

Schematic perspective view for explaining an example of a PDP Sectional drawing which shows an example of the film-forming apparatus of this invention (111) Graph showing the relationship between strength and filling rate Graph showing the relationship between the amount of water introduced and the (111) half width Graph showing relationship between emission intensity and (111) peak intensity Graph showing relationship between emitted light wavelength and emission intensity (Example) Graph showing the relationship between wavelength of emitted light and emission intensity (comparative example) Graph showing the relationship between EB current and emission intensity (comparative example) Electron micrograph of a protective film formed by introducing water Electron micrograph of a protective film formed without introducing water

DESCRIPTION OF SYMBOLS 1 ... Plasma display panel 3 ... Film-forming apparatus 10 ... First panel 14 ... Protective film 15, 16 ... Electrode (sustain electrode, scanning electrode) 32 ... Vacuum chamber 36 ... Evaporation source 41 ... Electron Gun 51 ... Transport route 55 ... Water inlet 56 ... Oxygen inlet

Reference numeral 1 in FIG. 1 shows an example of a plasma display panel.
The plasma display panel 1 includes first and second panels 10 and 20.
The first panel 10 has a first glass substrate 11, and a sustain electrode 15 and a scan electrode 16 are arranged on the surface of the first glass substrate 11 (one in FIG. 1 is illustrated). ).

The sustain electrodes 15 and the scan electrodes 16 are alternately arranged at a predetermined interval. Sustain electrode 15 and scan electrode 16 are separated from each other, and dielectric film 12 is formed between the surface and sustain electrode 15 and scan electrode 16. Therefore, the sustain electrode 15 and the scan electrode 16 are insulated from each other.
A protective film 14 is disposed on the entire surface of the dielectric film 12. Accordingly, the protective film 14 is located on each sustain electrode 15 and each scan electrode 16.

The second panel 20 has a second glass substrate 21. On the surface of the second glass substrate 21, address electrodes 25 are arranged in parallel to each other, and the address electrodes 25 are separated from each other. A dielectric layer 24 (insulating layer) is disposed between the surface of the address electrode 25 and the address electrode 25, and the address electrodes 25 are insulated from each other.

Between the address electrodes 25, a partition wall 23 is disposed along the longitudinal direction of the address electrodes 25. Any one of the phosphor films (red phosphor film 22R, green phosphor film 22G, and blue phosphor film 22B) containing fluorescent dyes of different colors is disposed between the adjacent barrier ribs 23. Each address electrode 25 is covered with a phosphor film 22R, 22G, or 22B of any one color through the dielectric layer 24.

In the first and second panels 10 and 20, the surface on which the protective film 14 is formed and the surface on the side on which the partition wall 23 is formed face each other, and the sustain electrode 15 and the scan electrode 16 are opposed to the address electrode 25. Are stuck together so that they are orthogonal to each other, and the space between the first and second panels 10 and 20 is sealed.

The partition wall 23 protrudes high from the surface of the second panel 20, and the tip thereof is in contact with the surface of the first panel 10. Accordingly, the space between the first and second panels 10 and 20 is divided by the partition wall 23, and each of the divided spaces (light emitting space 29) is filled with a sealed gas (for example, a mixed gas of Ne and Xe). ing.

Next, a process for lighting the plasma display panel 1 will be described.
When a voltage is applied between the selected scan electrode 16 and the address electrode 25, a write discharge (address discharge) occurs in the light emitting cell where these electrodes intersect, and wall charges accumulate in the light emitting cell.

Next, an AC voltage is applied between the selected scan electrode 16 and the sustain electrode 15 adjacent to the scan electrode 16. The protective film 14 is mainly composed of an MgO film mainly composed of a protective material composed of MgO, an SrO—CaO film composed mainly of a protective material composed of SrO and CaO, or a protective material composed of MgO and SrO. It is composed of an MgO—SrO film or the like. Such a protective film 14 has a high electron emission characteristic, and in the light emitting cell in which wall charges are accumulated by address discharge, electrons are discharged from the protective film 14 to cause a sustain discharge, the sealed gas is turned into plasma, and ultraviolet rays are generated.

Since ultraviolet light is emitted from the light emitting cell where the selected scanning electrode 16 and the address electrode 25 intersect, when the ultraviolet light is incident on the phosphor films 22R, 22G, and 22B located in the light emitting cell, the phosphor films 22R and 22G. , 22B are excited, and visible light of any one of red, green, and blue is emitted.

The first glass substrate 11 and the dielectric film 12 are each transparent. The protective film 14 is also made of a transparent metal oxide such as MgO or SrO, and its film thickness distribution is ± 5% to ± 10% so that the transparency is not impaired. It is transparent. Therefore, light (visible light) emitted from the light emitting cell is transmitted through the first panel 10 and emitted to the outside.

When a weaker voltage than that in the sustain discharge is applied between the selected scan electrode 16 and the sustain electrode 15 adjacent to the scan electrode 16 to cause a weaker discharge (erase discharge) than the sustain discharge, the light emission space The wall charge in 29 is neutralized, and the light emitting cell is turned off.

The protective film 14 is exposed in the space between the first and second panels 10 and 20, and when the light emitting cell emits light, the protective film 14 is exposed to plasma.
The protective film 14 is made of a material that is difficult to be etched by plasma, such as MgO or SrO. In addition, since the protective film 14 formed according to the present invention has a high filling rate as will be described later, it is more difficult to etch, and the dielectric film 12, the sustain electrode 15, and the scanning electrode 16 are protected by the protective film 14. The display panel 1 has a longer life than conventional ones.

Next, the film forming apparatus of the present invention used for manufacturing the plasma display panel 1 will be described.
Reference numeral 3 in FIG. 2 is an example of a film forming apparatus and has a vacuum chamber 32. The vacuum chamber 32 has a film forming chamber 34 and a material chamber 35, and the material chamber 35 is disposed below the film forming chamber 34 and connected to the film forming chamber 34. A preparation chamber 31 and an extraction chamber 33 are connected to the film formation chamber 34 via a gate valve 39.

The film forming chamber 34 is provided with a transfer device 50, and an object to be formed is carried into the film forming chamber 34 from the preparation chamber 31 while being held by the holding means 47 (carrier). The film is carried out to the take-out chamber 33 through a predetermined transfer path 51 in the film formation chamber 34.

The material chamber 35 is connected to the film forming chamber 34 at a position directly below the transfer path 51. Inside the material chamber 35, an evaporation source 36 is disposed immediately below a connection portion between the material chamber 35 and the film forming chamber 34. Therefore, the evaporation source 36 is positioned directly below the transport path 51, and the film formation target faces the evaporation source 36 while moving along the transport path 51.
The evaporation source 36 has a crucible (container), and a vapor deposition material is disposed in the crucible. Here, the vapor deposition material is a metal oxide.

The material chamber 35 is provided with an electron gun (electron beam generator) 41. An evacuation system 52 b is connected to the vacuum chamber 32, and when the inside of the vacuum chamber 32 is put into a vacuum atmosphere and the electron gun 41 is operated, an electron beam (electron beam) 42 is irradiated to the metal oxide of the evaporation source 36. The metal oxide vapor is released into the material chamber 35.

A restriction plate 38 is disposed in a portion of the vacuum chamber 32 where the material chamber 35 and the film forming chamber 34 are connected.
An opening (discharge port) 37 is formed at a position of the restriction plate 38 directly above the evaporation source 36, and the vapor passing through the discharge port 37 is discharged into the film forming chamber 34.

The film formation target passes through the film formation position 49 facing the evaporation source 36 through the discharge port 37 while moving along the transport path 51. The limiting plate 38 restricts the spread angle of the vapor discharged into the film forming chamber 34, so that the vapor enters the film forming object passing through the film forming position 49 with an incident angle within a predetermined range.

A water inlet 55 and an oxygen inlet 56 are provided at a position between the limiting plate 38 and the evaporation source 36 inside the vacuum chamber 32 (that is, inside the material chamber 35).
The water inlet 55 and the oxygen inlet 56 are connected to a gas supply system (not shown). From the water inlet 55 and the oxygen inlet 56, H ₂ O gas (water vapor, gaseous water), oxygen gas, Is introduced into the material chamber 35.

The water inlet 55 is closer to the evaporation source 36 than the oxygen inlet 56, the H ₂ O gas is exposed to the electron beam 42 to generate hydrogen, and the vapor of the metal oxide is exposed to the H ₂ O gas containing hydrogen. Then, a part of the vapor is reduced and the metal is dissociated.
The water inlet 55 is farther from the transport path 51 than the oxygen inlet 56. That is, the distance between the film formation target and the water introduction port 55 when the film formation target is closest to the water introduction port 55 is the distance when the film formation target is closest to the oxygen introduction port 56. It is longer than the distance between the film formation target and the oxygen inlet 56.

Therefore, the vapor exposed to the H ₂ O gas is also exposed to oxygen gas before reaching the film formation target, and the dissociated metal is oxidized to become a metal oxide before reaching the film formation target.
When the dissociated metal oxidizes, it emits light (ultraviolet rays). On the side wall of the material chamber 35, a window portion 44 (for example, a quartz window) that transmits the light is provided. A spectroscopic monitor 43 is disposed outside the material chamber 35. The light transmitted through the window 44 enters the light receiving unit of the spectroscopic monitor 43, and the spectroscopic monitor 43 measures the emission intensity of the incident light.

If the irradiation area of the electron beam 42 is increased with the output from the heating device (electron gun 41) or the power applied to the metal oxide per unit area being constant, the amount of evaporation of the metal oxide per unit time increases. The film formation rate is increased and the emission intensity is increased. The electron gun 41 and the spectral monitor 43 are connected to the control device 45. The measured value of the emission intensity is transmitted to the control device 45.

Investigating the relationship between the emission intensity and the deposition rate, and setting the relationship in the control device 45. If a desired film formation rate is set in the control device 45, the control device 45 compares the measured value of the emission intensity with the set relationship, and the irradiation area of the electron gun 41 so that the film formation rate becomes the set value. change.

A process of forming a protective film using the film forming apparatus 3 will be described.
First, in the preliminary test, the protective film is formed under the same conditions (metal oxide type, film forming pressure, heating temperature, transport speed, etc.) as when the protective film was actually formed, and formed at the film forming position. The relationship between the film thickness growth amount per unit time (static deposition rate) when the object is stationary and the emission intensity of a specific wavelength when the metal oxide evaporates is obtained.

The static film formation rate is determined in the range of 40 nm / second or more, and the determined static film formation rate and the relationship obtained in the preliminary test are set in the controller 45.
The preparation chamber 31, the extraction chamber 33, and the vacuum chamber 32 are evacuated by the evacuation systems 52a to 52c to form a vacuum atmosphere at a predetermined pressure. The first panel 10 in which the electrodes (sustain electrodes 15 and scanning electrodes 16) and the dielectric film 12 are formed on the first glass substrate 11 is used as a film formation target, and is held by the holding means 47 and charged. Carry it into the chamber 31.

Heating means 59 is disposed inside the preparation chamber 31 and the film forming chamber 34, and the first panel 10 is heated to a predetermined temperature and then carried into the film forming chamber 34.
A granular metal oxide is disposed in the evaporation source 36. The amount of water (steam) and oxygen introduced can be controlled by a flow controller (mass flow controller) (not shown) so that the introduced volume per unit time of water is larger than the introduced volume per unit time of oxygen. The metal oxide vapor is generated by irradiating the electron beam 42 while introducing water and oxygen.

When the first panel 10 is transported through the transport path 51 with the surface on which the sustain electrode 15 and the scan electrode 16 are formed facing downward, and passes through the position facing the evaporation source 36, the first panel 10 and the scan electrode 15 are scanned. The metal oxide vapor reaches the electrode 16 (here, the surface of the dielectric film 12) to form a metal oxide thin film (protective film 14).

The controller 45 measures the emission intensity every predetermined time or continuously measures the emission intensity, changes the irradiation area of the electron beam 42 so that the measured value of the emission intensity becomes a set value, and the protective film The static deposition rate of 14 is set to a predetermined rate of 40 nm / second or more. Since the static film formation rate is 40 nm / second or more and water is introduced in a larger amount than oxygen, the protective film 14 is oriented to (111), and the filling rate exceeds 82%.

If one end of the transport direction of the first panel 10 reaches the film forming position 49 and the staying time required for the one end to pass through the film forming position 49 is multiplied by the static film forming speed, the protective film is roughly obtained. The film thickness is 14. That is, when the film thickness of the protective film 14 is determined, the value obtained by dividing the film thickness by the static film formation rate is the residence time.

The first panel 10 in a state where the protective film 14 is formed moves on the transport path 51, then is carried out to the take-out chamber 33, cooled, and then carried out of the film forming apparatus 3.
If the carried out first panel 10 and the above-described second panel 20 are bonded together, and the sealed gas is disposed between the first and second panels 10 and 20, the plasma display panel 1 of FIG. can get.

The case where the protective film 14 is formed on the first panel 10 of the three-electrode AC type PDP has been described above. However, the present invention is not limited to this, and the protective film 14 is formed only on the second panel 20. Alternatively, the film may be formed on both the first and second panels 10 and 20. When the protective film 14 is formed on the second panel 20, the protective film 14 is disposed on at least each address electrode 25.

The metal oxide used in the present invention is MgO alone or a mixture of MgO and another metal oxide (either SrO or CaO or both).
When a mixture of metal oxides is used, the electron gun is controlled to stabilize film characteristics by measuring the emission intensity during oxidation of the dissociated metal for any one or more metal oxides in the mixture. It is possible to measure.

In the case of using a mixture of metal oxides, it is very difficult to monitor a plurality of substances by a conventional method (for example, a crystal oscillation type film formation controller, CRTM), but by monitoring the intensity of a specific wavelength, It is possible to control the characteristics of the protective film made of a plurality of types of metal oxides using the mixture.
The vapor deposition material is not limited to the metal oxide, but includes at least one kind selected from the group consisting of the above-described metal oxide, Ca, Al, Si, Mn, Eu, and Ti. An agent can also be added.

If the metal oxide is evaporated using a plasma gun, the metal oxide may be excessively dissociated and unoxidized metal may be mixed in the protective film. Since an unoxidized metal, particularly Mg, has high ignitability, in the present invention, the electron gun 41 is used and the metal oxide is evaporated by the electron beam 42. The electron gun 41 is not particularly limited, but a piercing electron gun is suitable in consideration of controllability and stability of the evaporation rate.

If the film thickness distribution of the protective film 14 becomes non-uniform, the optical characteristics deteriorate and it is not suitable for the first panel 10, so the film thickness distribution is ± 5% to ± 10% of the target film thickness (for example, 800 nm). Thus, the oscillation waveform of the electron beam 42 is determined.
The above has described the case where the control device 45 changes the irradiation area of the electron beam 42 to set the light emission intensity to the set value. However, the present invention is not limited to this, and the power density (W / cm ² ) of the electron gun 41 Alternatively, the emission intensity may be set to a set value.

However, when the power density is increased, bumping of metal oxide called splash occurs, causing the film formation target to be contaminated. Therefore, in the present invention, light emission is obtained by changing the irradiation area while keeping the power density constant. It is desirable to set the strength to a set value.

In FIG. 2, the preparation chamber 31 and the take-out chamber 33 are connected to the film formation chamber 34. However, when the tact time is early (short), it is not possible to secure a time for sufficiently heating the film formation target before film formation. A heating chamber is installed between the preparation chamber 31 and the film formation chamber 34. In addition, when it is not possible to secure a time for sufficiently cooling the film formation target after film formation, a cooling chamber is provided between the film formation chamber 34 and the take-out chamber 33.
Although the evaporation source 36 may be stationary, the evaporation source 36 may be rotated at a position directly below the conveyance path 51 in a plane parallel to the conveyance path 51.

Although the above has described the case where the protective film 14 is formed while the film formation target (first panel 10) is being conveyed, the present invention is not limited to this. For example, the protective film 14 may be formed by placing a substrate holder directly above the evaporation source 36 inside the material chamber 35 and holding the substrate holder so that the film formation target faces the evaporation source 36. . In this case, the distance between the evaporation source 36 and the film formation target does not change at least during the formation of the protective film 14.

When forming the protective film 14 without changing the distance between the evaporation source 36 and the film formation target, in order to obtain a film having a (111) crystal orientation and a filling rate of 82% or more, The film formation target held on the substrate holder has a film thickness growth amount per unit time (that is, film formation speed) of 40 nm / second or more, and other conditions (such as the amount of water and oxygen introduced) are film formation. This is the same as when film formation is performed while the object is being conveyed.

When the distance between the evaporation source 36 and the film formation target is not changed, the oxygen introduction port 56 is disposed closer to the film formation target of the substrate holder than the water introduction port 55, and the water introduction port 55 is introduced with oxygen. It is arranged near the evaporation source 36 rather than the mouth 56.
When the substrate holder is rotated and the film formation target is rotated in a plane facing the evaporation source 36, the film thickness distribution of the protective film 14 becomes uniform.

If the purity of the water introduced into the vacuum chamber is poor, the film quality deteriorates. Therefore, the water is preferably pure water (absorbance 0.01 or less at a wavelength of 210 nm to 400 nm, nonvolatile 5 ppm or less). In particular, when organic substances are contained in water, the discharge characteristics deteriorate, so the total organic carbon content is preferably 4 ppb or less.

The installation location of the water introduction port 55 is not particularly limited, but if it directly faces the vapor discharge port of the evaporation source 36 (for example, the opening of the crucible), the metal oxide may be deposited and the water introduction port 55 may be clogged. Therefore, it is desirable that the water inlet 55 does not face the vapor outlet or a shield is disposed between the water inlet 55 and the evaporation source 36.

Moreover, even if a large amount of water was introduced into the vacuum chamber, if the film formation rate was the same as before (less than 40 nm / second), the peak intensity of the (111) crystal orientation was small and did not reach the practical level. In the present invention, it is essential to introduce water into the vacuum chamber and to set the film formation rate to 40 nm / second or more (more desirably 140 nm / second or more).
The amount of water introduced is not particularly limited as long as it is larger than the amount of oxygen introduced, but it is preferably 200 sccm or more.

The internal pressure (film formation pressure) of the vacuum chamber 32 when forming the protective film 14 is not particularly limited. When H ₂ O gas and a smaller amount of oxygen are introduced, the impurity concentration of the protective film (even if the film forming pressure is as high as 5 × 10 ⁻² Pa or higher (for example, 0.2 Pa, 0.3 Pa, etc.)) In particular, impurities containing C), film density, (111) crystal orientation, and the like were not deteriorated, and the intensity distribution of crystal orientation was improved as compared with the prior art.

If film formation continues, metal oxides adhere to the inner wall surface of the vacuum chamber 32 and cause dust generation. Therefore, the vacuum chamber 32 needs to be periodically cleaned. When the film forming pressure was as low as less than 5 × 10 ⁻² Pa, the inside of the vacuum chamber 32 had to be evacuated for a long time (5 to 6 hours) after cleaning. If the film forming pressure is 5 × 10 ⁻² Pa or more, more desirably 1 × 10 ⁻¹ Pa or more, it is not necessary to evacuate the inside of the vacuum chamber 32 for a long time after cleaning.

<Crystal orientation and film density>
E1 to E4 in FIG. 3 show the relationship between the (111) strength and the filling rate of the protective film formed by introducing water so that the amount of oxygen introduced into the material chamber 35 is larger than the amount of oxygen introduced into the material chamber 35. Typical film forming conditions are shown in Table 1 below, and analysis results of water (H ₂ O gas) introduced into the material chamber 35 are shown in Table 2 below.

C1 to C3 in FIG. 3 show the relationship between the (111) strength and the filling rate of the protective film formed by introducing only oxygen without introducing H ₂ O.
About the protective film of an Example and a comparative example, the diffraction intensity and refractive index of (111) orientation were measured, and the filling factor (film | membrane density) was calculated | required from the refractive index. The refractive index was measured with an ellipsometer. When the refractive index is n, the filling rate (film density) is p, the spatial refractive index is nv, and the bulk refractive index is ns, the refractive index n is expressed by the following formula (1).

Formula (1) ... n = (1-p) nv + pns
Since the refractive index nv of the space is usually 1 in air and the refractive index of the bulk is 1.73 in the case of MgO single crystal, the filling rate p of MgO can be obtained from the refractive index by the following formula (2). .
Formula (2) ... p = (n-1) /0.73
As can be seen from FIG. 3, the filling rate of the MgO film having the (111) peak intensity of 3000 CPS was 88.7% in the comparative example, whereas it was 90.7% in the MgO film of the example, which was about 2 points. Improved.

Further, the (111) strength of the MgO film for obtaining a filling rate of 90% was 2450 CPS in the comparative example, but 3500 CPS in the example, which was improved by about 40% or more. From the above results, it can be seen that the protective film formed according to the present invention has both high film density (filling rate) and high (111) orientation.

<Relationship between water introduction amount and (111) half width>
The half-width of the (111) orientation peak was measured by changing the amount of water introduced. The relationship between the full width at half maximum and the amount of water introduced is shown in FIG. The horizontal axis in FIG. 4 indicates the amount of water introduced (sccm), and the vertical axis indicates the half width. The smaller the half width, the better the crystallinity. According to the present invention, the full width at half maximum was improved by about 40% as compared with the prior art, and it was confirmed that the protective film formed by the present invention has good crystallinity.
From the above, increasing the evaporation rate of MgO to increase the static film formation rate, and performing film formation while introducing water can significantly improve the crystallinity of the protective film compared to the conventional case. I understand.

<Relationship between emission intensity and (111) peak intensity>
Without changing the power density of the electron gun, the irradiation area was widened to evaporate MgO to form a protective film. The emission intensity at a wavelength of 285.2 nm when MgO was evaporated was measured with a spectroscopic monitor manufactured by Otsuka Electronics Co., Ltd. The (111) peak intensity of the formed protective film was determined. FIG. 5 shows the relationship between the emission intensity and the peak intensity.
As can be seen from FIG. 5, as the emission intensity increases, the (111) peak intensity increases and the film quality of the protective film is improved.

<Emission spectrum>
The wavelength and emission intensity of the emitted light when the protective film was formed under the film forming conditions shown in Table 1 above were measured. The measurement results are shown in FIG. As a comparative example, the wavelength and emission intensity of emitted light were measured when a protective film was formed under the film forming conditions shown in Table 1 except that the amount of water introduced was zero. The result is shown in FIG.

As is clear from comparison between FIGS. 6 and 7, in FIG. 6 where water was introduced, two peaks (wavelengths 285.2 nm and 280.2 nm) derived from the oxidation reaction of Mg could be confirmed, but water was introduced. In FIG. 7 where there was no two peaks could be confirmed.

FIG. 8 shows the result of measuring the emission intensity at a wavelength of 285.2 nm by increasing the power applied to the electron gun without introducing water. From FIG. 8, it can be seen that if the input power is increased, the emission intensity increases, but the emission intensity is extremely lower than when water is introduced. Is dissociated and recombined.

<Comparison of protective film characteristics with and without water introduction>
FIGS. 9 and 10 show electron micrographs of the protective film when water is introduced and the protective film when water is not introduced. The portions that appear black in FIGS. 9 and 10 are gaps between the MgO columnar crystals and the MgO columnar crystals. As the gap between the columnar crystals is smaller, the amount of impure gas adsorbed is reduced and etching is difficult.
9 and 10, it can be seen that FIG. 9 has fewer gaps between the columnar crystals, and that a protective film that is less likely to adsorb impure gas and less etched is formed when water is introduced.

The relationship between the dynamic film formation speed and the static film formation speed described in Table 1 will be described. The dynamic film formation speed is a unit representing the film formation speed when forming a film while transporting the substrate. It is the film thickness that is formed while the substrate moves 1 m per minute. If the dynamic film formation rate is converted by multiplying by a predetermined coefficient, the static film formation rate when the substrate is fixed to the evaporation source can be obtained.

The coefficient for converting the static deposition rate varies depending on the deposition apparatus to be used, but in this case, it is 2.12. If the static deposition rate is Rs and the dynamic deposition rate is Rd, the static deposition rate is static. The film formation rate Rs is expressed by the following mathematical formula (3).
Formula (3): Rs (ｓ / sec) = Rd (Å · m / sec) × 2.12

Claims (12)

1. While introducing oxygen into the vacuum chamber, the metal oxide disposed in the evaporation source is heated to generate the vapor of the metal oxide,
   A first panel having an electrode disposed on its surface is transported through a transport path in the vacuum chamber, passed through a film formation position facing the evaporation source, and protected from a metal oxide thin film on the electrode. After forming the film
   A method for manufacturing a plasma display panel, wherein the first panel is bonded to a second panel, and the protective film is manufactured to be exposed to plasma.
   While introducing water into the vacuum chamber so that the introduction volume per unit time is equal to or more than the introduction volume per unit time of the oxygen,
   Plasma transporting the first panel while evaporating the metal oxide so that the deposition rate of the protective film is 40 nm / second or more when the first panel is stationary at the deposition position. Display panel manufacturing method.
2. The first panel with electrodes on the surface is placed at the deposition position facing the evaporation source inside the vacuum chamber,
   While introducing oxygen into the vacuum chamber, the metal oxide disposed in the evaporation source is heated to generate the vapor of the metal oxide, and the metal oxide is deposited on the electrode of the first panel. After forming a protective film consisting of a thin film,
   A method of manufacturing a plasma display panel for manufacturing a plasma display panel in which the first panel is bonded to a second panel, and the protective film is exposed to plasma,
   While introducing water into the vacuum chamber so that the introduction volume per unit time is the same as or larger than the introduction volume per unit time of the oxygen,
   A method of manufacturing a plasma display panel, wherein the metal oxide is evaporated so that a film forming rate of the protective film is 40 nm / second or more.
3. The method for manufacturing a plasma display panel according to claim 1, wherein the metal oxide is evaporated by irradiating the metal oxide with an electron beam.
4. 4. The method for manufacturing a plasma display panel according to claim 1, wherein the vapor pressure of the metal oxide is generated at a total pressure of the vacuum chamber exceeding 1 × 10 ⁻¹ Pa. 5.
5. The method for manufacturing a plasma display panel according to any one of claims 1 to 4, wherein the metal oxide is MgO.
6. The method for manufacturing a plasma display panel according to any one of claims 1 to 4, wherein the metal oxide contains MgO, and one or both of SrO and CaO are added.
7. When evaporating the metal oxide, measure the emission intensity of light emitted into the vacuum chamber,
   The plasma display panel manufacturing method according to any one of claims 1 to 6, wherein an output of a heating device for evaporating the metal oxide is changed so that a measured value of the light emission intensity becomes a preset value. Method.
8. When evaporating the metal oxide, measure the emission intensity of light emitted into the vacuum chamber,
   The method for manufacturing a plasma display panel according to claim 3, wherein the irradiation area of the electron beam is changed so that the measured value of the emission intensity becomes a preset value.
9. A vacuum chamber; an evaporation source disposed in the vacuum chamber; a heating device for heating the vapor deposition material disposed in the evaporation source; a water inlet for introducing water into the vacuum chamber; A protective film forming apparatus having an oxygen inlet for introducing oxygen into
   A measuring device for measuring the emission intensity of light generated inside the vacuum chamber;
   Having a measuring device and a control device connected to the heating device;
   The control device is a film forming device configured to change an output of the heating device based on a light emission intensity transmitted from the measuring device.
10. 10. The film forming apparatus according to claim 9, wherein the heating device is an electron gun, and the control device changes an irradiation area of an electron beam emitted from the electron gun.
11. A transport device that transports a film formation target along a transport path inside the vacuum chamber;
    The film-forming object is made to face the evaporation source while moving along the transfer path,
    11. The film forming apparatus according to claim 9, wherein the water inlet is closer to the evaporation source than the oxygen inlet and is further away from the transfer path.
12. A substrate holder for holding the substrate at a position facing the evaporation source inside the vacuum chamber;
    11. The film formation according to claim 9, wherein the water inlet is closer to the evaporation source than the oxygen inlet and is farther from the substrate held by the substrate holder. apparatus.

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