KR100509260B1 - Substrate coated with one or more MgO layers and methods for manufacturing the same - Google Patents

Abstract

The present invention relates to a substrate having a width of at least 100 mm x 100 mm and coated with at least one MgO layer. The MgO layer of such a substrate is characterized by showing one or more abrupt peaks in the course of the measurement of the Φ-2Φ method. The invention also relates to a method of making such a substrate and a coating apparatus for the practice of the method.

Description

Substrate coated with one or more MgO layers and methods and apparatus for making the same

The present invention relates to a substrate having a width of at least 100 mm x 100 mm and coated with at least one MgO layer, and a method and apparatus for producing the same.

It is known to coat substrates having a relatively large surface area, in particular plasma display panels (PDPs), with high quality MgO by electron beam deposition. High quality is achieved such that the density of the deposited layer material is very high, i.e., 85 to 95% of the bulk material density, as compared to MgO bulk materials having a density p of 3.58 g / cm ₃ .

The Θ-2Θ method described in this specification is defined in F. Kohlrausch's Practical Physics Book 2, p. 23, 753 (B.G. Teubner, Stuttgart 1985). This method belongs to the Bragg method, which means to rotate the detector by 2Θ while rotating the crystal by the Θ angle.

As used herein, "peak at (x y z)" refers to a peak in a diagram measured by the Θ-2Θ method shown according to the (x y z) orientation of a crystal, as is typically used in crystallography.

"Extruded peak" means a peak protruding higher than another peak in the diagram measured by the Θ-2Θ method.

The appearance of a single peak in the diagram means that a higher grade peak also appears, for example when referring to a single peak at (111), it refers to the appearance of a second grade peak at (222).

The coating material deposited by the electron beam has the very serious disadvantage of not showing any protruding peaks in the diagram measured by the Θ-2Θ method.

The present invention provides a substrate having an area of at least 100 mm x 100 mm coated with at least one MgO layer, wherein the coating layer has a protruding peak in the diagram measured by the Θ-2Θ method. In particular, when the substrate of the present invention is a PDP substrate, it is very preferable to have a peak at (111) or to have a peak only at (111). Such substrates cannot be produced by electron beam deposition.

Also, instead of the peak at 111, one peak may appear at 200 and / or 220 or several additional peaks may appear.

In a suitable embodiment of the substrate according to the invention, for light having a wavelength of at least 400 to 800 mm and preferably 350 to 820 nm, the MgO layer has the following refractive index.

1.5 ≤ n ≤1.8,

Preferably 1.59 ≦ n ≦ 1.75.

As a more suitable embodiment of the present invention, the substrate preferably has a uniform surface roughness of 0.5 nm RMS to 18 nm RMS, as measured by AFM, in particular a layer thickness of 200 to 800 nm.

Although the substrate according to the invention has the advantage of having a protruding peak compared to conventional substrates, it is preferred that the density of the layer is at least 80% or at least 90% of the stoichiometric MgO bulk material density. The density (rho) of the MgO bulk material is 3.58 g / cm ₃ .

As a suitable embodiment, the coating layer MgO of the substrate according to the invention is stoichiometric.

Also. The present invention provides a method of making a substrate coated with at least one MgO layer and having a width of at least 100 nm x 100 nm, having a substrate having at least one raised peak in the diagram measured by the Θ-2Θ method. do.

The method comprises flowing a working gas through a slit between two sputter targets made of magnesium toward the substrate spaced from the end region of the slit so that the magnesium target has a purity of at least 99%. Introducing oxygen between the end regions, and setting the temperature of the substrate prior to performing the coating.

Therefore, the coating speed is increased by the reactive sputter coating method according to the present invention. High deposition of the target material is achieved. This makes it possible to manufacture the substrate of the present invention at a very low cost in industry. Argon is preferably used as the working gas, and oxygen is preferably used at least as part of the reaction gas. However, it has been found that even greater advantages can be obtained by using a reaction gas consisting almost of oxygen and hydrogen. The hydrogen component injected into the process atmosphere may be injected together with the working gas, but it is particularly preferable to be injected together with oxygen which is the reaction gas. The two reaction gases, oxygen and hydrogen, may be mixed in advance. In this case, hydrogen is injected at a rate of 0% (using pure oxygen as the reaction gas) to 50% with respect to the total reaction gas, preferably at a rate of 0 to 10%. The advantages obtained by using hydrogen gas are on the one hand affecting the roughness of the MgO layer and on the other hand affecting the crystal structure.

It is possible to control the surface roughness of the layer by injecting hydrogen around the process. That is, by injecting hydrogen around the process, the surface roughness can be reduced from 50%, for example, from 10 nm RMS to 5 nm RMS.

For example, in a pure oxygen reaction gas atmosphere, the crystal structure has a peak protruding from (111). Injecting hydrogen at a rate of 2.5% of the total reaction gas has a protruding peak at 220, and when injecting 5% hydrogen, a crystal structure of the MgO layer having a protruding peak at 200 is obtained.

Therefore, the surface roughness can be controlled similarly to each crystal structure of the MgO layer by controlling the hydrogen injected around the process.

Apparatus of the invention suitable for carrying out the method of the invention consist of:

Two Mg targets of magnesium material forming a slit and of at least 99% purity;

An anode and a gas supply device connected to a gas tank containing a working gas, the gas nozzle being positioned so that the gas flows toward an end portion without causing the gas to flow between targets;

A substrate carrier / conveyor device arranged to move the flat substrate through the slit and spaced apart from the second slit end opposite the first slit end;

An additional gas supply device operating between the crab 2 slit end region and the substrate carrier / conveyor device and connected to a gas tank containing a reactive gas containing oxygen.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 schematically shows the apparatus best suited for carrying out the method according to the invention and for producing the substrate. At least a similar device is EP-0 803 587 and corresponding US application Ser. No. 08 / 895,457, described as a reference of the present invention, wherein the device of FIG. Is referred to.

Of importance for this gas flow sputter source is at least one target pair consisting of two targets 1a, 1b defining the slits indicated in the Z-direction in FIG. 1. As shown in Fig. 1, the slits 3 are both open in the Z-direction, or as in the above-referenced patent. The length of the slit in the Z-direction can be 1600 mm. The target is preferably operated by a direct current motor (not shown), but an alternating current or direct current motor in combination with superimposed AC or pulsating DC operation is possible. In the end region of the slit 3, an anode 5 and a gas supply device are provided along the slit. The gas supply device 7 is connected to the working gas tank 9 containing argon through the adjusting member 9a.

An additional gas supply device 11 is provided in the end region of the slit opposite the gas supply device 7. This additional gas supply device is, as schematically shown, connected to a storage tank 13 containing oxygen via an adjusting member 13a. The gas nozzle in the gas supply device 11 is provided so that the gas flows toward the end of the target without causing the gas to flow directly between the targets to cause turbulence. The storage tank 13 also contains oxygen or oxygen containing a very small amount of hydrogen. In the case of a tank storing oxygen containing a very small amount of hydrogen, it is connected to a control member for controlling each gas or mixed in advance in the tank with a reaction gas mixture (oxygen / hydrogen). If necessary, the amount of hydrogen injected around the process is preferably supplied through the reaction gas supply device 11 and / or working gas supply device (7).

A substrate carrier / conveyor device 15 for moving a planar substrate having an area of at least 100 mm × 100 mm is provided over the end region of the slit with the oxygen gas supply device 11 as shown in the figure. It is. By the carrier / conveyor device 15, the substrate is moved perpendicular to the flow direction G of the working gas through the slit 3 and spaced apart from the end region of the slit containing the reaction gas supply device 11. It is. It is preferable that the relative movement of the substrate with respect to the slit 3 is continuously and linearly and continuously.

As shown in FIG. 1, for devices with slits 3 with open sides, the following geometry and operating parameters are suitable as shown in EP-0 863 587 above:

Total pressure of coating area B: 0.1-10 mbar;

Partial pressure of reaction gas: up to 10% of total pressure in coating area (B);

Reaction gas: O ₂ , or O ₂ and H ₂ , in the latter case H ₂ is 0 to 50%, preferably 0 to 10%, based on the total amount of reaction gas.

Outflow flow to working area (G), suitably through the slit opening of argon to coating area (B):

This flow is selected by the following Knudsen or viscosity:

Knudsen range: 10 ⁻² mbar · cm ≦ p .Φ ≦ 0.6 mbar · cm;

Viscosity range: 0.6 mbar · cm < p .Φ;

Where p represents the total pressure in the slit 3, Φ represents the width of the slit.

The gas flow is preferably selected as the Knudsen range, and the following ranges are also preferred:

10 sccm / cm ² ≤ F ≤ 200 sccm / cm ² ,

Where F represents the flow of working gas per area of the slit opening and suitably

20 sccm / cm ² ≤ F ≤ 50 sccm / cm ² .

Width of slit Φ, i.e. gap between targets 1a and 1b:

5 mm ≤ Φ ≤ 40 mm,

Suitably, Φ ≤ 25 mm,

More suitably 8 mm ≦ Φ ≦ 20 mm.

Depth of the slit in the direction G of FIG. 1 (length of the target) H _s :

1 cm ≦ H _s ≦ 20 cm.

Height of the slit L _z : for example, 1600 mm.

Similar to the magnetron, the tunnel-shaped magnetic field H is generated above the sputtering surfaces of the targets 1a and 1b, so it is measured parallel to the sputtering surface of the targets 1a and 1b at the midpoint of the slit, The range is preferred:

150 Gauss ≤ H ≤ 1200 Gauss,

Suitably, H ≥ 300 Gauss,

More suitably, 300 Gauss < H <800 Gauss.

The substrate temperature T in the region B is set by the heating / cooling device adjusted by the adjusting member 19a.

The coating apparatus shown schematically in FIG. 1 is manufactured and operated as follows:

Target 1a, 1b material: Mg ₃ N _{5 with a} purity of 99.95%;

Discharge voltage to grounded anode 5: 310 V;

Discharge current: 27 A;

Power density per area sputtering plane: 15 W / cm ² ;

Working gas: argon with flow rate of 8000 sccm;

Total pressure in zone B: 0.4 mbar;

Substrate temperature: 200 ° C., variable;

Substrate surface area: 300 × 400 cm ² ;

Dynamic deposition rate: 30 to 50 nm.m / min;

Distance D between substrate and slit end: 50 mm;

Moving speed of substrate through slit end (v): 0.7 m / min.

Fig. 2 shows a diagram in which the MgO layer in the PDP glass substrate coated with AF 45 glass according to the present invention is measured by the Φ-2Θ method. In the apparatus of FIG. 1, the flow rate of oxygen is regulated by the adjusting member 13a. By adjusting the flow rate of oxygen as shown in Figure 2, the height and angular position of the appearing peak can be adjusted. For PDP substrates, it is required that only one peak appear at (111) at an oxygen flow rate of 30 to 40 sccm. As shown in the figure, peaks of grade 2 are indicated at 222.

By adjusting the flow rate of the oxygen gas in the method of the present invention, the height and angular position of the appearing peak are adjusted, and different angular positions can be set as in (200) and / or (220).

As shown in FIG. 3, in the method or gas flow sputter source according to the invention of FIG. 1, the process parameters that may affect the height and angular position of the peak are the substrate temperatures T maintained during the coating process. Preferably, these parameters, i.e., the flow rate of the oxygen gas and the temperature of the substrate according to Fig. 2, are used to adjust the angular position and the height of the peak as desired.

In Fig. 4, a diagram of the coated substrate of the present invention in which an MgO layer having a thickness of 500 nm is deposited at T = 180 ° C. is shown by the Φ-2Θ method. Peaks (a) at (200), (220) and (311) are the results of measuring the polycrystalline MgO powder as a comparison object.

Figure 5 shows the absorption coefficients as a function of the wavelength of incident light for the coated substrate of the present invention on which the MgO layer was deposited.

As is well known, it is very uneconomical to obtain a substrate coated with a high quality MgO layer with a refractive index of 1.7 at the desired value by electron beam deposition. As can be seen in Figure 6, the coated substrate of the present invention also has a refractive index of 1.5 to 1.8, suitably represents 1.59 to 1.75. This is valid over the spectral range of at least 400 nm to 800 nm, and suitably also in the range of 350 to 820 nm, according to FIG. 6.

FIG. 7 shows the transmission for uncoated AF glass (a) and AF glass substrate (b) coated with a 1 μm thick MgO layer of the present invention.

8 returns to the apparatus of FIG. 1, with the substrate fixed against the slit and showing the coating speed distribution along the planar X-direction. As described above, the distance D between the substrate and the slit end is 50 mm.

9 shows the layer thickness distribution in the PDP substrate of the present invention having an area of 300 x 400 mm. The layer thickness distribution shows a very good distribution with ± 10% of the average thickness, which is very good despite the large area of the substrate.

10 shows surface roughness measured by AFM of a substrate of the present invention coated with a 500 nm thick MgO layer at 200 ° C.

The surface roughness in the substrate by the method of the present invention may have a wide range of 0.5 to 18 nm RMS, especially when measured by AFM by adjusting the substrate temperature T for a thickness of 200 to 800 nm.

In the substrate of the present invention, particularly the PDP substrate, peaks protruding from the high density MgO layer 111 are shown. Such substrates are most suitable for industrial use and can be produced in the most economical way. By the manufacturing method of the present invention, in addition to the fact that the target material can be used more than 70%, a very high deposition rate of 30 nm.m / min or more can be achieved as an economical production.

Note that only 10% of the target material is used by electron beam deposition. Although the experiment has not been carried out so far, it is believed that by using the gas flow sputter source described in EP-0 803 587, an even higher rate of deposition can be achieved when operated with a magnetron-type magnetic field.

Furthermore, Electron Probe Micro Analysis (EPMA) indicates that the deposited MgO layer of the present invention does not contain any working gas, ie argon. Since the surface roughness and the protruding peak can be adjusted, the surface per unit area for the PDP substrate of the present invention to generate a high secondary electron emission coefficient can be optimized. In this case, the protruding peak at (111) is optimal. In comparison with FIG. 3, at T = 200 ° C. in FIG. 10, a good surface roughness of about 0.5 nm RMS is achieved at (111) peak.

As described above, instead of injecting pure oxygen as a reaction gas around the process, up to 50% of the total amount of the reaction gas, preferably up to 10% of hydrogen may be injected. By injecting hydrogen gas, the surface roughness and crystal structure of the MgO layer can be controlled while keeping additional process parameters constant. If the remaining process parameters remain constant, hydrogen gas can be injected around the process as the reaction gas to reduce the surface roughness by 50%, from 10 nm RMS to 5 nm RMS.

In addition, by injecting hydrogen gas, the crystal structure of the MgO layer such as generation of protruding peaks can be controlled. In a predetermined process using oxygen, a peak protruding at (111) is generated and a peak protruding at (220) is generated when 2.5% of hydrogen is injected around the process relative to the total amount of reaction gas, and 5% is generated. When hydrogen is injected, a peak protruding from 200 appears. Therefore, the surface roughness and crystal structure of the MgO layer can be controlled by controlling the hydrogen gas inflow around the reaction gas.

1 is a schematic illustration of an apparatus for manufacturing a substrate according to the manufacturing method of the present invention,

FIG. 2 is a diagram showing peaks protruding from (111) or (200) under various oxygen supply states as measured by the Θ-2Θ method of a substrate produced by the method and apparatus according to the present invention;

3 is a diagram showing peaks with temperature of various substrates during coating of the substrate in accordance with the present invention;

4 is a diagram showing peaks of the polycrystalline MgO powder (a) as the substrate (b) and the comparative example of the present invention;

5 is a diagram showing the absorbance of a substrate according to the invention as a function of incident light wavelength,

FIG. 6 is a plot of refractive index as a function of incident light wavelength for the substrate of FIG. 5;

7 is a chart showing the spectral transmittances for the AF45 glass (a) compared as a carrier and the substrate (b) of the present invention containing the same;

FIG. 8 shows a distribution of the layers deposited along plane E shown in FIG. 1, showing a percentage of the maximum deposition thickness along the substrate in a fixed state relative to the coating source, FIG.

9 is a chart showing the distribution of MgO coating thickness on the PDP substrate of the present invention;

10 is a photograph showing surface roughness measured by AFM (Atomic Force Microscopy) of the substrate of the present invention coated at a substrate temperature of T = 200 ℃.

<Description of the symbols for the main parts of the drawings>

1a, 1b: target

3: slit

5: anode

7, 11: gas supply device

9: working gas storage tank

9a, 13a: adjusting member

13: reaction gas storage tank

15: Carrier / Conveyor Unit

Claims (42)

For substrates having a width of at least 100 mm x 100 mm and coated with at least one MgO layer, the MgO layer has one or more projected peaks in the diagram measured by the Θ-2Θ method, and the density of the layer is determined by A substrate characterized by at least 80% of the stoichiometric density (ρ) of 3.58 g / cm ³ . The substrate of claim 1, wherein the MgO layer exhibits peaks protruding at (200) and / or (220) and / or (111). A substrate according to claim 1 or 2, wherein the MgO layer has a refractive index n of 1.5 ≦ n ≦ 1.8 in at least the 400 to 800 nm light spectral range. The MgO layer according to claim 1 or 2, wherein the MgO layer has a surface roughness uniformly distributed over the substrate, and the surface roughness measured by AFM at a layer thickness of 200 nm to 800 nm is 0.5 to 18 nm RMS. Description to be made. The substrate of claim 1, wherein the density of the MgO layer is at least 90% of the stoichiometric density of the MgO bulk material. A substrate according to claim 1 or 2, wherein the MgO layer is formed of stoichiometric MgO. The substrate according to claim 1 or 2, wherein the substrate is a plasma display panel (PDP) substrate. The substrate according to claim 1 or 2, wherein the MgO layer is deposited by reactive sputtering. A method having a width of at least 100 mm × 100 mm, the surface of the substrate being coated with a MgO layer, wherein the MgO layer has a selectivity of (X Y Z) crystal orientation comprising the following steps: In the first zone where the working gas flows in. Sputtering Mg by discharging a plasma between the anode and the Mg cathode sputtering target made of Mg having a purity of at least 99%; Flowing the working gas from the first region to a second region adjacent the surface of the substrate; Injecting oxygen into the second region, and By selecting the above sputtering, working gas flow and oxygen injection steps, the MgO layer is deposited at a constant deposition rate of at least 5 nm / sec. Allowing the MgO layer to have a density of at least 80% of the stoichiometric MgO bulk material with a density (ρ) of 3.58 g / cm ³ . 10. The method of claim 9, further comprising defining a first region by two cathode sputtering targets made of Mg facing each other and defining slits. 11. The method of claim 10, further comprising generating a plasma discharge between the two cathode sputtering targets and the anode. 10. The method of claim 9, further comprising applying an electrical signal comprising direct current to the cathode sputtering target and the anode to perform plasma discharge. The method of claim 10, further comprising defining a second area by the end of the slit and the surface of the substrate such that the surface of the substrate is spaced parallel from the end of the slit. 10. The method of claim 9, further comprising the step of selecting such that said selectivity is a magnitude of (111), (200) and (220) crystal orientations. 10. The method of claim 9, further comprising moving the substrate to the second region, the surface of which is substantially perpendicular to the flow direction of the working gas. The method of claim 15, further comprising linearly moving the substrate having the surface. The method of claim 16, further comprising moving the substrate having the surface at a constant speed. 10. The method of claim 9, further comprising selecting a dynamic deposition rate of the MgO layer at least 35 nm.m / sec. 19. The method of claim 18, further comprising selecting a dynamic deposition rate of the MgO layer at least 30 nm.m / sec. 10. The method of claim 9, further comprising the step of selecting the height and angular position of the (X Y Z) peak. 10. The method of claim 9, further comprising selecting a property to have a peak protruding at (111). 22. The method of claim 21, wherein the (111) peak is the only peak of the property. 10. The method of claim 9, wherein the substrate comprises a MgO layer having a refractive index (n) of 1.5 ≦ n ≦ 1.8 in at least a 400 to 800 nm light spectral range. 24. The method of claim 23 wherein the refractive index n is such that 1.59 &lt; n &lt; 1.75. The method of claim 23, wherein the light spectral range is selected to be at least 350-820 nm. 10. The method of claim 9, wherein the MgO layer has a uniformly distributed surface roughness along the surface and has a range of 0.5 to 18 nm RMS as measured by AFM. 10. The method of claim 9, wherein the density of the MgO layer is at least 90% of the MgO bulk material density. The method of claim 9. A method of making a substrate having a layer composed of stoichiometric MgO. 29. The method of claim 28, wherein said layer consists of stoichiometric MgO. 10. The method of claim 9, wherein the plasma display panel is manufactured. 10. The method of claim 9, wherein the plasma display panel has a glass substrate. An apparatus for carrying out the manufacturing method according to claim 9, comprising two Mg targets 1a, 1b having an Mg purity of 99% or more and forming a slit 3, A gas supply device 7 having a gas nozzle for allowing gas to flow into an end region without directly flowing between targets is connected to the gas tank 9 and has an anode at an end region of the slit, and an end of the slit. A substrate carrier / conveyor device 15 for moving the substrate spaced from the end region B opposite the region to pass through the slit 3, disposed in the end region of the slit and the carrier / conveyor device 15 An additional gas supply device (11) connected to the reaction gas storage tank (13) to supply oxygen to the end region (B) between the substrates. 33. Apparatus according to claim 32, provided with a heating / cooling device (19) for the substrate. 34. The apparatus according to claim 33, wherein the heating / cooling apparatus (19) for the substrate can be controlled. A substrate according to claim 2, wherein the MgO layer has a peak protruding from (111). 36. The substrate of claim 35 wherein the peak is unique. 4. A substrate according to claim 3, wherein the light spectral range is at least 350 to 820 nm. 4. A substrate according to claim 3, wherein the optical refractive index n is 1.59? N? 1.75. 7. The substrate of claim 6, wherein the material of the MgO layer consists of stoichiometric MgO. 8. The substrate according to claim 7, wherein the plasma display panel substrate is made of glass. The substrate according to claim 8, wherein the MgO layer is produced by the method according to claim 9. 9. The substrate of claim 8 wherein the MgO layer is made by a Gas Flow Sputter Source device.