JP4553124B2 - Vacuum deposition method and EL display panel - Google Patents

Description

  The present invention relates to a vacuum deposition method and an EL display panel for forming a deposition film having a predetermined pattern on a surface of a transparent substrate by vacuum deposition.

  In recent years, a display panel (hereinafter referred to as an EL panel) in which a dot pattern of an organic EL (Electro Luminescence) element is formed on a transparent substrate has been developed as a display to replace a liquid crystal display, and its practical use has begun. An EL panel emits light by energy generated when holes and electrons are combined, and thus does not require a backlight and can be made extremely thin as compared with a liquid crystal display. In addition, since it has high contrast and high responsiveness, it is being put to practical use as a next-generation display.

  In the EL panel, an anode (IT: Indium Tin Oxide) is formed on a transparent substrate such as a glass substrate, and a cathode for injecting electrons is further formed. Between these anode and cathode, there is a light-emitting layer that emits light by combining holes and electrons and releasing energy, and the hole injection rate decreases between the light-emitting layer and the anode. A hole injection layer is provided between the light emitting layer and the cathode to prevent the electron injection rate and the holes entering the light emitting layer from being reduced. An electron transport layer is provided for preventing entry into the electron injection layer. Therefore, the EL panel is configured by adopting a configuration in which the above layers are sandwiched between an anode and a cathode. In order to drive each pixel of the EL panel, for example, an anode is formed two-dimensionally by a TFT (Thin Film Transistor) circuit, and the pixel emits light depending on whether or not a voltage is applied according to each pixel. It is possible to control whether or not.

  By the way, in the EL panel, it is necessary to form the light emitting layer on the transparent substrate with the dot pattern of the EL light emitting layer of the three primary colors of R, G, and B. Since it is necessary to form it densely on the substrate, the pattern formation is performed by a vacuum deposition method from the viewpoints of pattern miniaturization, adhesion strength to the transparent substrate, and the like. In vacuum deposition, a deposition source is disposed at a lower position of a chamber whose inside is in a vacuum state, and a holder member that detachably holds a transparent substrate to be deposited is provided at an upper position of the deposition source. As a vapor deposition source, a luminescent dye material is put in a crucible equipped with a heating means, and the crucible is heated to evaporate the luminescent dye material and deposit the luminescent dye material on the lower surface of the substrate held by the holder member. It is what I did.

  Here, in the vacuum chamber, in order to form the dot pattern of the luminescent dye material on the transparent substrate constituting the EL panel, the pattern is formed at a fine pitch interval while holding the outer peripheral portion of the transparent substrate. After depositing a luminescent dye material of one of the three primary colors with the metal mask plate in contact with the transparent substrate, the luminescent dye material of the remaining two colors is deposited after shifting by the pixel pitch. At this time, the surface to be processed on which the luminescent dye material is vapor-deposited is disposed on the transparent substrate, and the mask plate is brought into close contact with the surface to be processed after alignment with extremely high accuracy. Vapor deposition will be performed.

  Therefore, alignment with the mask plate is performed in a state where the outer peripheral portion of the transparent substrate is fixedly held in the vacuum chamber. However, since the transparent substrate is mainly made of a glass plate, how is the outer peripheral portion of the transparent substrate? It is a problem whether to hold the fixedly. As a means for holding the transparent substrate in a fixed manner, generally, vacuum adsorption may be considered. However, as described above, the luminescent dye material is deposited on the transparent substrate in a vacuum chamber in which a vacuum state is maintained. As a result, the transparent substrate cannot be fixedly held by vacuum suction. Therefore, a method of holding the outer peripheral portion of the transparent substrate with a clamp is conceivable. However, since a fine dot pattern is deposited, the transparent substrate must be held in an extremely stable state. Therefore, it is necessary to firmly hold the outer peripheral portion of the transparent substrate with the clamp member. However, if the transparent substrate is held too strongly, the transparent substrate may be damaged. In particular, a transparent substrate made of a glass material has a very low frictional force, and cannot be held in a stable state unless it is held very firmly.

Therefore, for example, Patent Document 1 discloses a structure in which a sheet magnet is used as a member for fixing and holding the transparent substrate, and the mask plate is held by attracting the transparent substrate by the magnetic force of the sheet magnet. .
JP 2002-105622 A

  In the invention of Patent Document 1 described above, the mask plate is fixed to the mask holder, the transparent substrate is arranged close to the mask plate so as to face the mask plate, alignment is performed, and the two are overlapped, and then the sheet magnet is attached. By mounting on a transparent substrate, the structure which makes a magnet hold | maintain a mask board via a transparent substrate with magnetic force is taken. At this time, it is necessary to align the transparent substrate and the mask plate disposed on the upper part of the mask plate fixed to the mask holder. At the time of alignment, in order to keep the surface to be processed of the transparent substrate and the mask plate in non-contact, the outer peripheral portion of the transparent substrate is held by a clamp member or the like. In addition, the mask plate can be aligned by maintaining a planar shape with a certain amount of tension, for example, by adhering and fixing the mask plate to the mask holder with an adhesive or the like. When aligning the transparent substrate and the mask plate, the alignment marks formed on the transparent substrate and the mask plate are observed with a camera such as a CCD camera to achieve fine alignment. Formed at corners.

  By the way, in recent years, EL panels have come to be used thin because of the demand for space saving. Along with this, the transparent substrate constituting the EL panel must naturally satisfy the demand for thinning, and therefore, the transparent substrate having a very thin thickness is used. As described above, since the outer peripheral portion of the transparent substrate is held and alignment with the mask plate is performed, the central portion of the large and thin transparent substrate is bent by its own weight.

  When the transparent substrate and the mask plate in which such bending occurs are aligned, if there is no space between the transparent substrate and the mask plate, the transparent substrate and the mask plate at the bending portion (the central portion of the transparent substrate) Will be partly in contact. Here, when the position is adjusted for alignment, either the transparent substrate or the mask plate (mainly the transparent substrate) moves in the horizontal direction. Damage may occur. In particular, in the EL panel, a plurality of luminescent dye materials of layers such as R, G, and B are sequentially deposited on a transparent substrate, and then the next color is deposited by shifting by the pixel pitch. If one or two luminescent dye materials are vapor-deposited on the surface to be processed of the transparent substrate and the above contact problem occurs, a problem of color blur occurs in the already-deposited luminescent dye material, and an EL panel is obtained. Cannot be used.

  Of course, if the alignment is performed with the distance between the transparent substrate and the mask plate as far as possible, the possibility of the above-described contact problem is low. That is, if the alignment is performed by separating the transparent substrate and the mask plate beyond the maximum deflection amount of the transparent substrate, the problem of contact at the central portion does not occur. However, there is a problem that high-precision alignment cannot be performed if the distance between the transparent substrate and the mask plate is increased in consideration of the bending of the transparent substrate.

  That is, in order to perform high-precision alignment, an alignment mark is recognized using a camera with a shallow depth of focus in order to increase the resolution. As described above, in order to perform alignment with high resolution, it is necessary to use one having a shallow focal depth as much as possible. Therefore, alignment must be performed by placing the transparent substrate and the mask plate in very close positions. Don't be.

  In particular, EL panels tend to have higher densities and higher pixels, and are required to have extremely high alignment accuracy. Therefore, there is a demand to perform alignment using a camera with high resolution. Therefore, it is necessary to align both the transparent substrate and the mask plate as close as possible. On the other hand, as described above, when the transparent substrate is made thinner and larger, the problem of contact between a part of the transparent substrate (center portion) and the mask plate at the time of alignment must be avoided.

  Therefore, the present invention can align a thin and large transparent substrate and a mask plate for forming a dot pattern on the surface to be processed of the transparent substrate in close proximity, and at the same time, the mask is formed by bending the transparent substrate. An object of the present invention is to provide a vacuum deposition method and an EL display panel that can prevent contact with a plate.

  The vacuum vapor deposition method of the present invention is a vacuum vapor deposition method for forming a vapor deposition film on a surface of a transparent substrate by vacuum vapor deposition so as to have a predetermined pattern, and a surface to be treated on which the vapor deposition film of the transparent substrate is vapor-deposited. A mask plate made of a thin plate of magnetic metal material having the predetermined pattern is arranged on the side facing the surface to be processed, and is formed at a plurality of positions at each corner of the transparent substrate. In order to align the mask plate and the transparent substrate on the basis of the alignment mark that is present, the transparent substrate is slightly moved in the anti-self-weight direction so that the central portion thereof is farthest from the mask plate. The mask plate and the transparent substrate are brought close to each other with the convex curve, and the alignment mark formed on the mask plate and the transparent mark corresponding to the alignment mark are formed. And said alignment mark of the substrate was observed with the same camera view, characterized in that alignment.

  The vacuum deposition method of the present invention can perform high-precision alignment using a camera with a shallow depth of focus, and can simultaneously avoid problems such as color blur due to contact between the transparent substrate and the mask plate. .

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is an explanatory diagram showing a state in which a transparent substrate 1 on which a luminescent dye material is deposited and a mask plate 2 for forming a predetermined dot pattern on the transparent substrate 1 are aligned. Here, although not shown, a luminescent dye material is deposited on the surface to be processed of the transparent substrate 1 in a vacuum chamber that is evacuated by a vacuum pump or the like and maintained in a vacuum state.

  The transparent substrate 1 is a large and thin transparent substrate, and a luminescent dye material is deposited on one surface (surface to be processed) to form an EL panel. The transparent substrate 1 is fixed and held by a rotatable clamp member 6 and a support base 7 supported on a support base 7 at the outer peripheral portion thereof, and maintains its posture even in a hollow state. Further, as shown in FIG. 3, alignment marks 1 </ b> M for alignment with the mask plate 2 are formed at the corners of the transparent substrate 1.

  As shown in FIGS. 2 (a) and 2 (b), the mask plate 2 has a plurality of dot pattern punched portions 2 </ b> B, and the pattern of the punched portions 2 </ b> B is formed on the transparent substrate 1 during vacuum deposition. Transcribed. In this case, in order to increase the transfer accuracy of the dot pattern, the mask plate 2 is made of an extremely thin metal plate. Therefore, in order to give the outer peripheral portion of the mask plate 2 shape retention, a metallic reinforcement A frame 2A is attached. The mask plate 2 to which the reinforcing frame 2A is attached is fixed to a part (or all) of the reinforcing frame 2A by an appropriate method. At this time, the mask plate 2 can be maintained in a planar state by being fixed with tension. In addition, it is assumed that alignment marks 2M, which will be described later, are formed at the corners of the mask plate 2, respectively.

  The camera 5 is a camera such as a CCD camera, and performs alignment with reference to the alignment mark 2M formed at the corner corner of the mask plate 2 and 1M formed at the corner corner of the transparent substrate 1. Taking both alignment marks (mainly enlargement photography). Accordingly, although two cameras 5 are shown in FIG. 1, the alignment marks 1M and 2M are normally formed at four locations, and therefore it is assumed that four cameras 5 are provided. The transparent substrate 1 and the mask plate 2 are superimposed at an accurate position by finely adjusting either the transparent substrate 1 or the mask plate 2 in the horizontal direction with reference to both alignment marks photographed by the camera 5. It will be.

  Here, the camera 5 takes an image of the alignment marks 1M and 2M, and alignment is performed. At this time, the alignment marks 1M and 2M are aligned at close intervals as shown by the interval SL in FIG. It is preferable. That is, since both alignment marks 1M and 2M need to be aligned with high accuracy, it is necessary to photograph both alignment marks 1M and 2M very clearly. Therefore, as indicated by SL in FIG. 3, it is preferable to perform alignment using a camera 5 having a shallowest depth of focus. Therefore, it is necessary to arrange the transparent substrate 1 and the mask plate 2 as close as possible.

  Therefore, it is necessary to align the transparent substrate 1 and the mask plate 2 as close to each other as possible, but when the outer peripheral portion of the large and thin transparent substrate 1 is clamped, the central portion is bent. Therefore, the transparent substrate 1 and the mask plate 2 come into contact with each other at the bent portion when alignment is performed. Here, it is conceivable to apply tension to the transparent substrate 1 at the time of clamping. However, if the tension is applied by increasing the clamp strength, the clamp member 6 slips and damages the transparent substrate 1 made of a glass material. May occur. Therefore, when the transparent substrate 1 is clamped, the center portion is inevitably bent.

  Therefore, in order to avoid contact between the transparent substrate 1 and the mask plate 2, the transparent substrate 1 is held so as to be slightly curved in the anti-self-weight direction. Therefore, when the transparent substrate 1 is supported by the rotatable clamp member 6 for fixing and holding the transparent substrate 1, it is brazed so as to be inclined slightly upward (anti-self-weight direction). As a result, a force that rises toward the center acts on the transparent substrate 1 and a force for tilting the transparent substrate 1 in the anti-self-weight direction acts, so that the transparent substrate 1 protrudes in the anti-self-weight direction. Curve to shape. And since the component of the force which goes to an anti-self-weight direction is suppressed by the clamp members 6 and 6, as shown in FIG. 1, the transparent substrate 1 maintains the attitude | position curved slightly toward the anti-self-weight direction. .

  In this state, the mask plate 2 is disposed so that the surface to be processed of the transparent substrate 1 faces the mask plate 2, and the transparent substrate is moved to a position where the alignment marks 1M and 2M become the depth of field SL of the camera 5. 1 and the mask plate 2 are brought close to each other. At this time, since the transparent substrate 1 is brought close to the substrate while maintaining a posture slightly curved in the anti-self-weight direction, the transparent substrate 1 and the mask plate 2 are not brought into contact with each other at the center portion. Then, after observing the alignment marks 1M and 2M with the camera 5 and performing fine alignment, the surface to be processed of the transparent substrate 1 and the mask plate 2 are brought into contact with each other. Lowers the magnet 3 (magnet member that attracts and holds the mask plate 2 by magnetic force) disposed on the upper side of the opposite surface to contact the transparent substrate 1. Since the magnet 3 is a magnet member and the mask plate 2 is a magnetic metal material, a magnetic force acts between the two via the transparent substrate 1, and the mask plate 2 is completely against the surface to be processed of the transparent substrate 1. Close contact with. Thereby, the mask plate 2 can be firmly fixed and held by the magnetic force from the upper part of the mask plate 2 without strongly fixing and holding the outer peripheral portion of the transparent substrate 1, and a partial gap or the like may be generated. Absent.

  In such a state, any one of a plurality of layers of the luminescent dye material that becomes the material of the luminescent dye material disposed in the lower part of the vacuum chamber (for example, in this embodiment, deposition of the three primary colors of R, G, and B) When the crucible in which one of the colors is stored is heated, the luminescent dye material evaporates, and the luminescent dye material is deposited on the surface to be processed of the transparent substrate 1 in the dot pattern of the mask plate 2. Is done. At this time, since the mask plate 2 is completely in close contact with the surface to be processed of the transparent substrate 1, the transfer accuracy of the luminescent dye material is improved, and high-accuracy film deposition can be performed.

  Next, in order to deposit the remaining two colors of the luminescent dye material on the surface to be processed of the transparent substrate 1, another luminescent dye material is deposited again with the mask plate 2 shifted by the pixel pitch. Need to do. Therefore, first, the magnet 3 is retracted, and the contact state between the transparent substrate 1 and the mask plate 2 is released. Then, alignment is performed in a state shifted by the pixel pitch, the transparent substrate 1 and the mask plate 2 are brought into contact again, and the magnet 3 is lowered from above. Since a magnetic force acts between the magnet 3 and the mask plate 2 via the transparent substrate 1, the mask plate 2 is in close contact with the surface to be processed of the transparent substrate 1. In this state, by evaporating the luminescent dye material, two luminescent dye materials of the three primary colors can be deposited. Further, by performing the same process for the remaining one color, it is possible to deposit light emitting dye materials of all three primary colors.

  Incidentally, as described above, the transparent substrate 1 and the mask plate 2 are brought into contact with each other after being aligned with reference to the alignment marks 1M and 2M, but there is a possibility that a slight deviation may occur at the time of contact. Therefore, after the contact, the alignment marks 1M and 2M are again observed by the camera 5 to inspect whether the alignment marks are misaligned. Here, if there is a deviation, it is necessary to perform alignment again by separating the transparent substrate 1 and the mask plate 2 which are in close contact with each other as an alignment error. In addition, after the deposition of the luminescent dye material of one of the three primary colors is completed, it is necessary to perform alignment again in order to perform the deposition of the luminescent dye material of another color. At this time, the mask plate 2 is made of a metal plate having a very small thickness in order to increase the transfer accuracy of the dot pattern, so that the mask plate 2 has an elastic force.

  In FIG. 4, assuming that the alignment position is a position indicated by a virtual line, even when the transparent substrate 1 is separated upward from the mask plate 2, even if the transparent substrate 1 is lifted to the solid line position in FIG. The part may rise together with the transparent substrate 1 in a state where the parts are in close contact. That is, since the mask plate 2 has a very small thickness, the contact force acts when the mask plate 2 is brought into contact with the transparent substrate 1. At the same time, the mask plate 2 has an elastic force, so that the mask plate 2 rises together with the transparent substrate 1 in a state in which a part (mainly, the central portion) of the mask plate 2 is pressure-bonded to the transparent substrate 1 due to the adhesion force. However, it may be greatly bent. And as the thickness of the mask plate 2 becomes thinner, a larger elastic force acts. Therefore, if the transparent substrate 1 is not largely separated from the mask plate 2, the two cannot be completely separated, and the contact state is partially present. Maintained.

  Therefore, the transparent substrate 1 is raised to a position where both of them are completely separated beyond the amount of pressure bonding due to the bending based on the elastic force of the mask plate 2. Thereafter, when descending again, alignment is performed by bringing the transparent substrate 1 and the mask plate 2 close to each other until the alignment marks 1M and 2M are within the focal depth of the camera 5. As a result, even if the alignment for fine adjustment in the horizontal direction is performed again, the transparent substrate 1 and the mask plate 2 can be aligned in a state of being completely separated from each other. Therefore, the problem of color blur caused by rubbing the luminescent dye material already attached to the transparent substrate 1 does not occur.

  As described above, when the transparent substrate 1 and the mask plate 2 are aligned, the transparent substrate 1 is curved in a slightly convex shape in the anti-self-weight direction in advance, thereby forming the alignment formed at the corners. Even if the marks 1M and 2M are aligned at close positions, the central portion of the transparent substrate 1 does not bend, and as a result, the transparent substrate 1 and the mask plate 2 do not contact each other. Therefore, even if the depth of focus is very shallow, the transparent substrate 1 and the mask plate 2 can be very close to each other, and both alignment marks can be photographed very clearly, and alignment can be performed with high accuracy. The above-mentioned contact problem can be avoided, and color blur does not occur.

  Further, when the alignment is performed again, the transparent substrate 1 and the mask plate 2 are largely separated from each other by the adhesion force between the transparent substrate 1 and the mask plate 2 and the elastic force based on the bending amount of the mask plate 2. The contact problem that occurs can be avoided and color blurring does not occur.

It is explanatory drawing when a transparent substrate and a mask board align and contact | abut. It is sectional drawing and a top view of a mask board. FIG. 2 is an enlarged view of the vicinity of the alignment mark in FIG. 1. It is explanatory drawing when a mask board bends greatly.

Explanation of symbols

1 Transparent substrate 2 Mask plate 3 Magnet 5 Camera
6 Clamping member 7 Support base

Claims (5)

A vacuum deposition method for forming a deposited film so as to form a predetermined pattern on the surface of a transparent substrate by vacuum deposition,
A surface to be processed on which the vapor-deposited film of the transparent substrate is deposited is disposed facing downward, and a mask plate made of a thin magnetic metal material having the predetermined pattern is disposed on the side facing the surface to be processed. In order to align the mask plate and the transparent substrate with reference to alignment marks formed at a plurality of corners of each of the transparent substrates,
In the state where the transparent substrate is curved in a slightly convex shape toward the anti-self-weight direction so that the central portion is most separated from the mask plate, the mask plate and the transparent substrate are brought close to each other, A vacuum deposition method, wherein the alignment mark formed on the mask plate and the alignment mark of the transparent substrate corresponding to the alignment mark are observed and aligned in the same camera field of view.   The vacuum deposition method according to claim 1, wherein the transparent substrate is curved in a slightly convex shape in the anti-self-weight direction by holding an outer peripheral portion thereof with a clamp member. After the transparent substrate and the mask plate are aligned and brought into close contact with each other, a magnet member made of an electromagnet or a permanent magnet is brought into contact with the transparent substrate from the surface opposite to the surface to be processed of the transparent substrate, and the magnet Holding the mask plate by a magnetic force acting between a member and the mask plate;
The vacuum deposition method according to claim 1, wherein a deposition material is attached to the surface to be processed of the transparent substrate through the mask plate.   When the transparent substrate and the mask plate are brought into close contact with each other during alignment and then aligned again due to misalignment, the transparent substrate and the mask plate are separated in the vertical direction by a stroke necessary for complete separation of the transparent substrate and the mask plate. 4. The vacuum vapor deposition method according to claim 3, wherein the vacuum deposition method is made to approach to a distance for performing alignment again. The vapor deposition material adhering to the surface to be treated is a luminescent dye material of three primary colors of R, G, and B,
After aligning said transparent substrate and the mask plate is brought into close contact with said transparent substrate and the mask plate in a state in which the mask plate by the magnet member is held by suction on the transparent substrate, the luminescent dye material of the three primary colors out after depositing the one color luminescent dye material, and the pixel pitch Shifts apart the mask plate from the transparent substrate,
After aligning the mask plate and the transparent substrate, the mask plate and the transparent substrate are brought into close contact with each other, and the mask plate is attracted and held on the transparent substrate by the magnet member. After vapor-depositing a luminescent dye material of one color among the luminescent dye materials, the mask plate is separated from the transparent substrate and shifted by a pixel pitch,
After aligning the mask plate and the transparent substrate, the mask plate and the transparent substrate are brought into close contact with each other, and the mask plate is attracted and held on the transparent substrate by the magnet member. Evaporating the luminescent dye material,
Vacuum deposition process according to claim 4, wherein the that form a light emitting layer comprising a three primary colors to the treated surface.

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