JP2005054244A - Substrate tray of film deposition system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate tray with which the cracks of a glass substrate is less liable to occur by reducing a temperature difference between a mask part and a film deposition part in the glass substrate. <P>SOLUTION: The substrate tray is carried into a film deposition system in a state of holding a substrate, and is arranged oppositely to a thin film material source. A mask for depositing a thin film into a prescribed shape is arranged between the tray having an opening through which thin film material grains pass and the substrate, and the emissivity of both the surface of the mask is controlled to ≥0.2. Further, ruggedness is formed on both the surfaces of the mask. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a substrate tray of a film forming apparatus, and more particularly to a substrate tray used for forming a MgO protective film or the like of a plasma display panel in a predetermined pattern.

The demand for plasma display panels (PDPs) is increasing year by year as a thin wall-mounted television together with a liquid crystal panel. Along with increasing the size and performance of the panel, a film forming apparatus and a film forming method are intended to improve productivity such as yield and throughput. Is being studied.
For example, in the process of forming the MgO protective film of the PDP, the glass substrate is placed on the substrate tray and transported onto the vapor deposition source in the vacuum vapor deposition apparatus to form the MgO film. At this time, a mask having a predetermined shape is disposed and vapor-deposited so that a thin film is not deposited on the peripheral portion of the glass substrate that becomes the bonded seal portion or the wiring drawing portion.

6 and 7 show a configuration example of the tray 2 and the mask 4 of the conventional substrate tray 1.
As shown in the exploded perspective view of FIG. 6A and the cross-sectional view of FIG. 6B, a flat plate rectangular frame-shaped mask 4 is mounted on the tray 2 having openings, and the substrate 5 is mounted thereon. Placed. Here, the mask 4 is not limited to a flat plate shape, and for example, as shown in the cross-sectional view of FIG. it can.
Further, the substrate tray 1 of FIG. 7 has a structure in which the tray function and the mask function are integrated, and the mask portion 4 is formed integrally with the tray 2 body. 7A is an exploded perspective view, FIG. 7B is a sectional view, and FIG. 7C is a partially enlarged view.

  However, when thin film formation is performed using such a conventional substrate tray, there is a problem that if the input power to the evaporation source is increased in order to increase the film formation speed, the glass substrate is easily damaged during film formation. As a result, it has been found that this tendency becomes more remarkable as the substrate becomes larger and the input power increases. Various processes are performed on the substrate until completion, and the glass substrate is handled, and the substrate is transferred and transported between substrate trays (substrate holders). There is a situation that it is easy to enter and to break easily.

The inventors of the present invention conducted various studies in order to pursue this cause. As a result, the temperature differs between the mask portion and the film forming portion of the glass substrate, and this temperature difference (ΔT ) Increases, and the thermal stress σ generated in the glass substrate increases as shown by the equation (1), and the glass substrate is easily broken. Here, α is a thermal expansion coefficient, E is a Young's modulus, and ν is a Poisson's ratio.
σ = α × E × ΔT / (1-ν) (1)

As a measure for preventing glass breakage caused by the temperature difference ΔT in the substrate, for example, a mask larger than the actually required substrate is used, and a mask provided with an opening in an extra region in addition to the thin film formation region Has been proposed. By using a mask with such a structure, a thin film is deposited in an extra area and the substrate temperature rises, so the temperature difference between the mask part and the film formation part decreases, resulting in a decrease in yield due to distortion and cracking of the substrate. Can be prevented. The extra area is cut and discarded.
JP 2001-152318 A

  However, although the above-mentioned measures can solve some problems such as glass cracking to some extent, it is necessary to cut an excessive part in a subsequent process using a substrate larger than necessary, and thus productivity is reduced. There was also a problem of high costs. Furthermore, there has been a problem that the film forming apparatus itself is also increased in size.

  Therefore, the present inventor has made various studies on the film forming method and the mask structure in order to suppress the substrate temperature difference ΔT between the film forming part and the mask part as much as possible without causing the above problems. For example, by placing a heater on the back side of the substrate and heating the substrate from the back side with its radiant heat, the temperature difference in the glass substrate can be reduced. A more general solution is required. On the other hand, when a film formation experiment was performed using masks of various materials, it was found that the temperature difference ΔT of the glass substrate changed depending on the material and the surface state. Conventionally, the contact portion with the glass substrate is generally a flat surface so as not to damage the substrate. However, the surface of the mask is roughened by subjecting it to surface treatment such as blasting. As a result, it was found that the temperature difference ΔT was further reduced.

  The present invention has been completed by further studies based on such knowledge, solves the above-mentioned conventional problems, reduces the temperature difference between the mask part and the film forming part of the glass substrate, and returns to the thermal stress. It is an object of the present invention to provide a substrate tray that is less susceptible to substrate cracking.

The substrate tray of the present invention is a substrate tray that is transported while holding the substrate inside the film forming apparatus and is disposed to face the thin film material source, and has a tray and a substrate having openings through which the thin film material particles pass. A mask for forming a thin film in a predetermined shape is arranged between and the emissivity of both surfaces of the mask is 0.2 or more.
By using a mask having a material or surface state with an emissivity of 0.2 or more in this way, the temperature difference between the mask portion and the film forming portion of the glass substrate during film formation can be reduced, so that higher speed can be achieved. The thin film can be formed and the productivity can be improved.

  Further, it is preferable that irregularities are formed on both surfaces of the mask, and the irregularities are preferably 3 to 10 μm in terms of surface roughness Ra. That is, by providing the unevenness, the emissivity can be further increased, the substrate temperature difference can be further reduced, and even higher emissivity can be obtained by setting the surface roughness Ra to 3 to 10 μm. It is possible to substantially suppress the occurrence of scratches on the substrate.

  In addition, acid treatment or blast treatment is preferably used for the formation of the surface irregularities. For example, in the blast treatment, irregularities with a desired roughness may be formed by the material, diameter and energy of the particles. Similarly, the uneven layer may be formed by thermal spraying using particles of various materials and diameters.

  Furthermore, it is preferable that the mask and the tray are in partial contact with each other, that is, by thermally separating the mask and the tray, heat is prevented from escaping from the mask to the tray having a large heat capacity. As a result, it is possible to further suppress a decrease in the substrate temperature on the back surface of the mask and further reduce the temperature difference between the mask portion and the film forming portion. Furthermore, by disposing an insulator between the mask and the tray, the escape of heat to the tray can be further suppressed.

  In the present invention, the thickness of the mask is 0.1 to 5 mm, more preferably 0.5 to 3.0 mm. By using a mask in this range, even in a larger glass substrate, the temperature difference in the substrate can be further suppressed and glass breakage can be prevented.

  According to the present invention, by setting the emissivity of the mask surface to 0.2 or more, the substrate temperature distribution at the time of film formation or the thermal stress of the substrate can be reduced, and as a result, the power supplied to the evaporation source or the like is increased. However, since the glass substrate can be prevented from cracking, the deposition rate can be increased and the throughput can be improved.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view showing a configuration example of a substrate tray of the present invention, (a) an exploded perspective view, (b) a sectional view, (c) a partially enlarged view, and (d) a plan view.
As shown in the figure, the substrate tray 1 of this embodiment includes a tray 2 having an opening and a mask 4, and the mask is placed on a plurality of mask support members 3 provided on the inner peripheral wall portion of the opening. The The glass substrate 5 is placed on this mask, and the entire substrate tray is transported between the processing chambers.

  For the tray 2, a SUS plate having a thickness of about 3 to 10 mm is usually used, and an opening corresponding to the size of the glass substrate is formed. Further, the mask support member 3 improves the thermal separation performance between the tray and the mask, and prevents the mask heat from escaping to the tray to prevent the substrate temperature on the back side of the mask from being lowered. Make it as small as possible. For example, the size of each support member is preferably about 3 to 10 mm in width, and the length is preferably about 2/3 of the mask width. In order to further enhance the thermal separation, it is preferable to use a material having a low thermal conductivity (for example, glass, polymer, etc.) as the material of the mask support member. In this manner, the temperature difference between the mask portion and the film forming portion of the glass substrate can be further reduced, vapor deposition with a larger power can be performed, and higher throughput can be achieved.

  For the mask, a material or surface state in which the surface emissivity is 0.2 or more is selected. As materials, for example, aluminum, nickel, tungsten, copper, titanium, molybdenum, tantalum and iron and alloys or oxides thereof, carbon, graphite, alumina, silica, zirconia, SiC, TiC, AlN, SiN, etc. Metals or insulators can be used. For materials having an emissivity of less than 0.2, the surface may be roughened by acid treatment, blast treatment, or the like, and the emissivity may be 0.2 or more, or may be coated by thermal spraying or the like. Furthermore, these may be combined. Usually, Ra of 3 to 10 μm is suitably used as the surface roughness, which helps increase the substrate temperature of the mask portion and suppresses the generation of scratches on the glass substrate.

  The thickness of the mask having the configuration shown in FIG. 1 is usually 0.1 to 5 mm (more preferably 0.5 to 3.0 mm). In FIG. 1, a rectangular frame shape is used as the mask shape. However, for example, when the glass substrate is finally cut to obtain two pieces, a mask having a shape bridged at the center is used, for example. It is done.

  In the present invention, the emissivity of the mask is measured as follows. That is, a mask to which a thermocouple is attached in advance is heated with a heater, and the heater is adjusted so that the mask becomes 300 ° C. Subsequently, the temperature of the mask is measured with a radiation thermometer, the emissivity is adjusted so that the reading of the radiation thermometer becomes 300 ° C., and the value at this time is set as the emissivity of the mask.

A vapor deposition apparatus that continuously conveys a glass substrate and continuously forms an MgO film using the above substrate tray is shown in FIG.
In the vapor deposition apparatus, the substrate tray loading chamber 10, the vapor deposition chamber 11, and the substrate tray unload chamber 12 are connected via gate valves 16 and 17, and the substrate 5 is placed on or taken out from the substrate tray 1 on both sides thereof. The platforms 13 and 14 are arranged via gate valves 15 and 18. Inside the platforms 13 and 14 and the chambers 10, 11, and 12, a conveyance roller 30 (for example, Japanese Patent Application Laid-Open No. 9-279341) that is generally used for conveyance of a substrate tray is attached. The chambers 10, 11, and 12 are connected to exhaust devices 22, 23, and 24 through valves 19, 20, and 21, respectively, and controlled to a predetermined degree of vacuum.
Further, a vapor deposition source is attached below the conveyance roller 30 in the vapor deposition chamber 11. In the example shown in the figure, for example, a ring hearth 27 for storing the vapor deposition material 28 and a plasma gun 25 for irradiating the vapor deposition material with an electron beam and evaporating it are disposed. An electron gun may be used instead of the plasma gun.

First, a glass substrate 5 (for example, 1.5 m square, 2.8 mm thickness) is placed on the substrate tray 1 to which a mask is attached on the platform 13. The gate valve 15 is opened and the transport roller 30 is driven to transport the substrate tray 1 to the load chamber 10. After closing the gate valve 15 and evacuating the interior to about 10 Pa, for example, the substrate is heated to about 100 to 200 ° C. by a heater (not shown).
Thereafter, the gate valve 16 is opened and the substrate tray 1 is moved to the vapor deposition chamber 11. The inside is exhausted to 10 ⁻¹ to 10 ⁻² Pa, and the substrate is heated to about 100 to 200 ° C. by a heater (not shown) disposed on the back side of the substrate tray 1. While introducing oxygen gas at a flow rate of about 100 to 200 cc / min, the plasma gun 25 in the vapor deposition chamber 11 is driven to irradiate and heat the evaporating material 28 in the ring hearth 27 with the electron beam 26. The vapor deposition material evaporates, reaches the glass substrate 5 through the opening of the substrate tray, and a film grows on the surface at high speed. When the MgO film having a desired thickness is formed, the driving of the plasma gun and the introduction of oxygen gas are stopped.
After the deposition is completed, the substrate tray 1 is sent to the unload chamber 12 and cooled to a predetermined temperature. Then, the gate valve 18 is opened and the substrate tray 1 is carried out to the platform 14. The substrate tray 1 from which the processed substrate has been taken out is transported to the platform 13, an unprocessed substrate is placed thereon, and the substrate tray 1 is transported again to the load lock chamber 10 to form an MgO film in the same manner.

As described above, when the MgO film was repeatedly formed, for example, blasting was performed on both surfaces of a stainless steel mask to form various irregularities, and the emissivity at 300 ° C. was set to 0.2 or more. It was confirmed that the glass substrate damage accident was reduced.
As an example, a SUS plate with a thickness of 3 mm and a width of 20 mm is blasted on both sides and a mask with a surface roughness (Ra) of 6.0 μm is used. FIG. 3 shows the temperature change of the glass substrate in the mask portion when the MgO film is formed at a double film formation rate, and FIG. 4 shows the change in temperature difference between the mask portion and the film formation portion (Example). . Here, the thermocouple was attached to the center of the substrate and the center of the mask width on the back side of the substrate. In addition, the mask support member having a width of 5 mm and a length of 15 mm was used, and the mask support members were attached at intervals of about 100 mm.

For comparison, a temperature change was measured in the same manner when using a blasted SUS plate (Ra <1 μm), and the results are shown in FIGS. 3 and 4 (comparative example).
The masks of the comparative example and the example were heated to 300 ° C. on a hot plate while monitoring the temperature with a thermocouple fixed in advance to the mask, and a radiation thermometer (broadband radiation thermometer IR-BHT11 manufactured by Chino Co., Ltd.). ) And adjusting the emissivity of the radiation thermometer so that the measured value in the vicinity of the contact portion of the thermocouple is 300 ° C. The emissivity measured in this way was 0.07 and 0.4, respectively.

  As can be seen from FIG. 3, the substrate temperature in the mask portion of the example is heated to a higher temperature than in the comparative example. Further, as shown in FIG. 4, the temperature difference ΔT between the mask portion and the film forming portion of the substrate is 20 ° C. or more smaller than the value of the comparative example in this embodiment, and the substrate tray of this embodiment is used. This shows that the thermal stress can be further reduced.

  That is, in this embodiment, a mask having an emissivity of 0.4 is used, and the contact portion between the mask and the tray is made small so that the heat of the mask is prevented from escaping to the tray side. Radiant heat from the evaporation source efficiently heats the mask, and the temperature of the glass substrate disposed on the back surface can be increased. As a result, the temperature difference of the substrate between the mask portion and the film forming portion is reduced, and the glass breakage frequency can be reduced. That is, even if the power input to the vapor deposition source is increased, the temperature difference between the mask portion and the film forming portion of the glass substrate can be kept small. As a result, high-speed film formation is possible without causing breakage of the glass, and higher throughput can be realized.

Next, another embodiment of the present invention is shown in FIG.
5A is an exploded perspective view of the substrate tray, FIG. 5B is a plan view, and FIG. 5C is a cross-sectional view.
The mask of the present embodiment is not a frame-shaped mask as shown in FIG. 1, but a plate-shaped mask is fixed to the tray. That is, the end portions of the plate-like mask 4 corresponding to each side of the opening of the tray 2 are fixed using, for example, screws or other jigs. In addition, when using it by overlapping a mask like the case of FIG. 5, from a viewpoint of intensity | strength and prevention of the wraparound of a vapor deposition particle, it is 0.1-3.0 mm (preferably 0.5-1.5 mm) in thickness normally. A mask is used.
Moreover, it is preferable to arrange | position an insulator between a mask and a tray, and the material and surface state of a mask are as having mentioned above.

It is a schematic diagram which shows an example of the board | substrate tray of this invention. It is a schematic diagram which shows an example of the MgO protective film manufacturing apparatus of PDP. It is a graph which shows the time change of the mask part temperature of a board | substrate. It is a graph which shows the time change of the temperature difference of the mask part of a board | substrate, and the film-forming part. It is a schematic diagram which shows the other example of the board | substrate tray of this invention. It is a schematic diagram which shows an example of the conventional board | substrate tray. It is a schematic diagram which shows the other example of the conventional board | substrate tray.

Explanation of symbols

1 substrate tray,
2 trays,
3 mask support member,
4 mask,
5 glass substrate,
10 Substrate tray loading chamber,
11 Deposition chamber,
12 Substrate tray unloading chamber,
13 Substrate for board loading,
14 Substrate removal platform,
15-18 gate valve,
19-21 valves,
22-24 exhaust system,
25 Plasma gun,
26 electron beam,
27 Ringhaas,
28 Vapor deposition material,
29 evaporated particles,
30 Transport roller.

Claims (7)

  A substrate tray that is transported while holding the substrate inside the film forming apparatus and disposed opposite the thin film material source, and has a predetermined gap between the tray and the substrate having an opening through which the thin film material particles pass. A substrate tray characterized in that a mask for forming a thin film in a shape is disposed, and the emissivity of both surfaces of the mask is 0.2 or more.   The substrate tray according to claim 1, wherein irregularities are formed on both surfaces of the mask.   The substrate tray according to claim 2, wherein the unevenness has a surface roughness Ra of 3 to 10 μm.   4. The substrate tray according to claim 2, wherein the unevenness is formed by blasting.   4. The substrate tray according to claim 2, wherein the unevenness is formed by thermal spraying.   The substrate tray according to claim 1, wherein the mask and the tray are in partial contact with each other.   The substrate tray according to claim 1, wherein an insulator is disposed between the mask and the tray.

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