Evaporation source for vacuum deposition equipment

Abstract

To provide a vapor deposition source for vacuum vapor deposition system that is enabled to evaporate a vapor deposition substance efficiently without any excessive thermal load placed on the vapor deposition substance filling a storage box.SOLUTION: A vapor deposition source DS1 for a vacuum vapor deposition device Dm which is arranged in a vacuum chamber 1, and evaporates a solid vapor deposition substance Ms for vapor deposition on an object Sw of vapor deposition comprises a storage box 4 filled with the vapor deposition substance and first heating means 6a capable of heating the vapor deposition substance in the storage box, and further comprises a vaporization body 5 which has a part 5a dipped in the vapor deposition substance M1 heated to be molten in the storage body, and remaining parts 5b, 5c extended outwardly from in the storage box, the vaporization body being so constituted that the molten vapor deposition substance permeates the remaining parts through capillarity. The vapor deposition source is provided with second heating means 6b which heats and vaporizes the vapor deposition substance having permeated the remaining parts.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an evaporation source for a vacuum evaporation apparatus that is disposed in a vacuum chamber and that evaporates a solid evaporation material and deposits the material on an object to be evaporated. [Background technology]

[0002] For example, in the manufacturing process of an organic EL device, there is a step of evaporating a solid deposition material (organic material) such as α-NPD or 2-TNATA onto a deposition target such as a substrate in a vacuum atmosphere to deposit a predetermined thin film on the surface of the deposition target, and a vacuum deposition apparatus is generally used for the deposition step. An evaporation source used in such a vacuum deposition apparatus is known, for example, from Patent Document 1. This apparatus includes a crucible (container box) with an open vertical top surface and a heating means for heating the crucible. The heating means used is an induction heating type equipped with an induction coil (see the Prior Art section).

[0003] When a predetermined thin film is deposited on the surface of a deposition target by using a vacuum deposition device equipped with the above deposition source, for example, a powdered deposition material is filled in a crucible, and an AC current is passed through an induction heating coil in a vacuum chamber with a vacuum atmosphere. Then, the crucible is heated by Joule heat generated by resistance loss when an induced current (eddy current) flows in the crucible, and the deposition material in the crucible is heated mainly by heat transfer from the crucible, and the deposition material in the crucible melts (liquefies). When heated to a predetermined temperature according to the vapor pressure, the melted deposition material vaporizes. At this time, the deposition material vaporizes only from the liquid surface facing the top opening of the crucible. Therefore, if the entire crucible is heated so that the temperature reaches the point where the upper part of the deposition material filled in the crucible vaporizes, excessive heat load is applied to the deposition material in the lower part of the crucible, resulting in problems such as thermal degradation of the deposition material (in the case of organic materials, thermal decomposition, thermal denaturation, etc.). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2010-1529 A Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above, an object of the present invention is to provide an evaporation source for a vacuum evaporation device that can efficiently evaporate an evaporation material filled in a storage box without applying an excessive thermal load to the evaporation material. [Means for solving the problem]

[0006] In order to solve the above problems, the deposition source for a vacuum deposition apparatus of the present invention is arranged in a vacuum chamber and is used to evaporate a solid deposition material and deposit it on an object to be deposited. The deposition source comprises a storage box filled with the deposition material and a first heating means capable of heating the deposition material in the storage box, and further comprises an evaporator, a portion of which is immersed in the deposition material melted in the storage box by heating and whose remaining portion extends outward from within the storage box, the evaporator being configured so that the melted deposition material permeates into the remaining portion by capillary action, and is characterized in that a second heating means is provided for heating and vaporizing the deposition material that has permeated into the remaining portion.

[0007] According to the present invention, when the container is filled with, for example, a powder-like deposition material at a predetermined filling rate and the container is heated to a predetermined temperature (melting temperature) by the first heating means in a vacuum atmosphere, the deposition material in the container is melted (liquefied) mainly by heat transfer from the wall surface of the container. A part of the liquefied deposition material permeates into the remaining part of the vaporized body by capillary action. Then, the deposition material that has permeated into the remaining part is further heated by the second heating means to a predetermined temperature (vaporization temperature) according to the vapor pressure, and is vaporized (note that when the deposition material that has permeated into the remaining part is vaporized, the liquefied deposition material permeates the remaining part sequentially by capillary action, so that continuous deposition can be performed). In this way, in the present invention, by dividing the container into a part for melting the deposition material and a part for vaporizing the deposition material, the first heating means only needs to add and hold the amount of heat required to melt the deposition material in the container as the part for melting the deposition material. Therefore, application of an excessive heat load to the deposition material is suppressed as much as possible, and further, by providing the second heating means, the deposition material that has permeated into the remaining portion can be heated and efficiently vaporized.

[0008] In the present invention, the vaporizer is made of a mesh member, and a through hole for allowing the remaining part to pass through can be provided on the upper wall of the storage box or on a side wall of the storage box located above the vapor deposition material filled in the storage box. As the mesh member, for example, a wire rod made of a heat-resistant material such as stainless steel (SUS304, etc.), titanium, tantalum, tungsten, molybdenum, or carbon and having a predetermined diameter, or a wire rod twisted with a plurality of such wire rods and woven in a plain weave or twill weave to form a thin space (gap) between the wire rods can be used. This not only realizes a configuration in which a part of the vapor deposition material liquefied in the storage box permeates into the remaining part of the vaporizer by capillary action, but also increases the amount of heat radiated from the wall surface of the storage box when the storage box is heated, so that the vapor deposition material in the storage box can be heated more efficiently. Here, in the above-mentioned conventional example, when adjusting the amount of vaporization of the deposition material, the temperature of the entire crucible is controlled by changing the amount of heat applied to the crucible (container box) by the heating means, but the amount of vaporization of the deposition material cannot be adjusted with good response by the heat capacity of the crucible. On the other hand, in the present invention, the heat capacity of the part that vaporizes the deposition material can be made smaller than that of the container box, so that the amount of vaporization can be adjusted with good response. In addition, since the vaporization of the deposition material can be stopped simply by reducing the amount of heat applied by the second heating means, for example, when replacing a film-formed target object with a film-formed target object in a vacuum chamber, it is possible to suppress the wasteful consumption of the deposition material, and furthermore, the deposition on the target object can be quickly resumed.

[0009] In the present invention, the remaining part of the vaporized body may include a permeation part disposed with a gap from the inner sidewall of the storage box, and a vaporized part located outside the storage box and heated by a second heating means. According to this, when the vapor deposition material melted in the storage box permeates the vaporized body by capillary action, the liquefied vapor deposition material is attracted to the gap between the inner sidewall of the storage box and the permeation part and rises up, so that the liquefied vapor deposition material can be reliably permeated into the vaporized part. The size of the gap is not particularly limited as long as it exhibits capillary action, but is set to 100 μm or less, more preferably 60 μm or less. In addition, the gap does not need to be uniformly provided over the entirety, and may be in partial (point) contact, for example. Furthermore, when the object to be vapor-deposited is a substrate having a predetermined area, forming the vaporized part as a flat plate is advantageous because it allows vapor deposition on the substrate at a high vapor deposition (film formation) rate.

[0010] Furthermore, in the present invention, it is preferable that the vaporized portion of the vaporizer includes a portion extending downward from the upper surface of the container box, which is advantageous in that when the liquefied vapor deposition material is caused to permeate into the vaporized portion, gravity is added to the capillary phenomenon, so that the liquefied vapor deposition material can be more reliably caused to permeate into the vaporized portion. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view illustrating a vacuum deposition apparatus including a deposition source according to an embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of a deposition source according to the present embodiment. [Diagram 3] FIG. 3(a) is an enlarged cross-sectional view of a deposition source according to another embodiment, and FIG. 3(b) is an enlarged cross-sectional view of a deposition source according to still another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, with reference to the drawings, an embodiment of the deposition source for a vacuum deposition apparatus of the present invention will be described taking as an example a case where a deposition target is a glass substrate (hereinafter referred to as "substrate Sw") of a predetermined thickness having a rectangular outline, a deposition substance is a solid organic material Ms that evaporates (vaporizes through a liquid phase) by heating, and a predetermined organic film is deposited on one side of the substrate Sw. In the following, terms indicating directions such as "upper" and "lower" are based on FIG. 1 which shows the vacuum deposition apparatus in the installed position.

[0013] 1 and 2, a vacuum deposition apparatus Dm including a deposition source DS1 of this embodiment includes a vacuum chamber 1, to which a vacuum pump is connected via an exhaust pipe (not shown or described), and a vacuum atmosphere can be formed by evacuating the chamber to a predetermined pressure (vacuum level). A substrate transport device 2 is provided above the vacuum chamber 1. The substrate transport device 2 has a carrier 21 that holds a substrate Sw with its lower surface, which serves as a film formation surface, open, and can transport the carrier 21, and thus the substrate Sw, in one direction within the vacuum chamber 1 at a predetermined speed by a driving device (not shown). A known substrate transport device can be used as the substrate transport device 2, and therefore further description will be omitted.

[0014] A plate-shaped mask plate 3 is provided between the substrate Sw transported by the substrate transport device 2 and the deposition source DS1. In this embodiment, the mask plate 3 is attached integrally to the substrate Sw and transported by the substrate transport device 2 together with the substrate Sw. The mask plate 3 can also be fixedly disposed in the vacuum chamber 1 in advance. The mask plate 3 is formed with a plurality of openings 31 penetrating in the plate thickness direction, and the deposition range of the evaporated organic material Mv on the substrate Sw is limited at positions where these openings 31 are not present, so that a film is formed (deposited) on the substrate Sw in a predetermined pattern. The mask plate 3 is made of metals such as invar, aluminum, alumina, and stainless steel, as well as resins such as polyimide. The deposition source DS1 of this embodiment is provided on the bottom surface of the vacuum chamber 1 so as to face the substrate Sw.

[0015] The deposition source DS1 has a cylindrical container 4 filled with an organic material Ms. The container 4 is made of a material with good thermal conductivity and high melting point (heat resistance), such as stainless steel (SUS304, etc.), titanium, tantalum, tungsten, molybdenum, or carbon. In this case, the upper wall 41 of the container 4 can be detachably attached to a main body 42 of the container 4, which has an open top. The shape of the container 4 is not limited to this, and for example, a rectangular parallelepiped shape can also be used. The container 4 is provided with a mesh member 5 as a vaporizer. The mesh member 5 is made of a heat-resistant material such as stainless steel (such as SUS304), titanium, tantalum, tungsten, molybdenum, or carbon, and is formed into a sheet-like shape with thin spaces 52 (gaps) formed between the wires 51 over the entire surface thereof by twisting a plurality of such wires 51 to a predetermined diameter (for example, in the range of Φ0.015 mm to Φ0.45 mm) (see the enlarged view in FIG. 1).

[0016] The mesh member 5 is inserted into the storage box 4 from above with its opening side at the top, and its tip (lower end) is placed in contact with the lower surface 42a of the storage box 4. In this case, for example, a groove (not shown) may be formed in the lower surface 42a of the storage box 4, and the lower end of the mesh member 5 may be press-fitted into the groove to be fixed. In addition, the upper wall portion 41 is provided with a slit hole 41a as a through hole along a virtual circumference centered on the hole axis of the mesh member 5, so that the outer peripheral surface of the mesh member 5 can be inserted. The outer diameter of the mesh member 5 is set so that the outer peripheral surface of the mesh member 5 faces the inner surface 42b of the storage box 4 over its entire surface and with a predetermined gap D1. The size of the gap D1 is not particularly limited as long as the gap D1 exhibits capillary action, but is set to 100 μm or less, more preferably 60 μm or less. The gap D1 does not need to be uniform over its entirety, and may be in partial (point) contact. For example, depending on the diameter and weaving method of the wire 51 constituting the mesh member 5, the mesh member 5 may be fitted inside the storage box 4 so that multiple gaps extending in the vertical direction are formed between the wires in contact with the inner surface 42b of the storage box 4.

[0017] In a state where the mesh member 5 is installed in the storage box 4, when the solid organic material Ms in the storage box 4, which is filled at a predetermined filling rate, is melted, a part of the mesh member 5 is immersed in the liquefied organic material Ml, and this becomes an immersed portion 5a, as shown in Fig. 2. Then, of the remaining part of the mesh member 5 located above the liquid level of the liquefied organic material Ml and extending outward from the storage box 4, a part corresponding to the outer circumferential surface of the mesh member 5 becomes a permeated portion 5b into which the liquefied organic material Ml permeates due to capillary action, and a bottom portion connected to this permeated portion 5b and parallel to the upper wall portion 41 of the storage box 4 becomes a vaporized portion 5c heated by a second heating means described later.

[0018] The deposition source DS1 also includes a first heating means 6a provided so as to cover the periphery of the storage box 4, and a second heating means 6b disposed between the upper wall portion 41 of the storage box 4 and the vaporizing portion 5c. As the first and second heating means 6a and 6b, known heaters such as sheath heaters and lamp heaters can be used. Also, the heating means 6a and 6b can be configured with an induction heating coil that heats the storage box 4 by induction heating. Examples of the organic material Ms used for deposition in the deposition source DS1 of this embodiment include α-NPD and BAHI8.

[0019] When the organic material Ms is deposited on the substrate Sw using the deposition source DS1, the storage box 4 is filled with the solid organic material Ms at a predetermined filling rate in the air atmosphere (see FIG. 1). Then, the vacuum chamber 1 is evacuated and the storage box 4 is heated by the first heating means 6a, whereby the solid organic material Ms melts and liquefies mainly due to heat transfer from the wall surface of the storage box 4. In this case, since the storage box 4 has an upper wall portion 41, when the storage box 4 is heated by the first heating means 6a, the upper wall portion 41 of the storage box 4 is also heated, and the solid organic material Ms is also heated by radiant heat from there.

[0020] A part of the liquefied organic material Ml is attracted by capillary action to the gap D1 between the inner side surface 42b of the storage box 4 and the permeated part 5b of the mesh member 5, and rises upward. In addition, the liquefied organic material Ml also permeates the remaining parts 5b, 5c of the mesh member 5 by capillary action, and at this time, as a part of the liquefied organic material Ml rises upward through the gap D1, a stronger capillary action is generated, so that the liquefied organic material Ml reliably permeates up to the vaporized part 5c. Then, the vaporized part 5c into which the liquefied organic material Ml has permeated is heated to a predetermined temperature by the second heating means 6b according to the vapor pressure, and the organic material Ml in the vaporized part 5c is vaporized. As a result, the organic material Mv vaporized from the vaporization portion 5c is scattered toward the substrate Sw and adheres to and accumulates thereon, forming a predetermined thin film on the surface of the substrate Sw. (Note that as the organic material Ml that has permeated into the vaporization portion 5c is vaporized, the liquefied organic material Ml gradually permeates into the vaporization portion 5c due to capillary action, allowing continuous deposition.)

[0021] According to the above embodiment, by dividing the storage box 4 into a portion where the solid organic material Ms is melted and a portion outside the storage box 4 where the liquefied organic material Ml is vaporized, the first heating means 6a only needs to apply and maintain the amount of heat required to melt the organic material Ms inside the storage box 4 as the portion where the organic material Ms is melted. This prevents excessive heat load from being applied to the organic material Ms as much as possible, and by providing the second heating means 6b, the organic material Ml that has permeated into the vaporization portion 5c as the remaining portion can be heated and efficiently vaporized. Furthermore, since the heat capacity of the vaporization section 5c that vaporizes the organic material Ml is smaller than that of the storage box 4, the amount of vaporization can be adjusted with good responsiveness, and furthermore, the vaporization of the organic material Ml can be stopped simply by reducing the amount of heat applied by the second heating means 6b. Therefore, for example, when replacing a substrate Sw on which a film has been formed with a substrate Sw before a film is formed within the vacuum chamber 1, it is possible to prevent the organic material Ml from being wasted, while deposition on the substrate Sw can be quickly resumed simply by increasing the amount of heat applied to the vaporization section 5c by the second heating means 6b.

[0022] Although the embodiment of the present invention has been described above, various modifications are possible without departing from the scope of the technical concept of the present invention. In the above embodiment, the mesh member 5 formed by twill weaving the wires 51 has been described as an example of the vaporizer, but as long as the liquefied organic material Ml can be permeated from the liquefied organic material Ml to the remaining parts 5b, 5c exposed to the space in the storage box 4 by capillary action, the present invention is not limited to this. For example, the wires 51 may be plain woven or two or more plain woven sheets may be layered. In the above embodiment, the mesh member 5 formed into a cylindrical shape corresponding to the inner side surface 42b of the storage box 4 is provided by using the inner side surface 42b of the storage box 4, but the present invention is not limited to this. For example, a stainless steel flat plate may be erected on the lower surface 42a of the storage box 4, and the erected flat plate may be regarded as the inner surface of the storage box 4, and a sheet-like mesh member may be provided on the flat plate with a predetermined gap D1 between them. In the above embodiment, the mesh member 5 is formed to correspond to the inner side surface 42b of the storage box 4, and the outer surface of the mesh member 5 faces the entire inner side surface 42b of the storage box 4, but this is not limited to this. For example, a sheet-like member may be curved into an arc shape to face part of the inner side surface 42b of the storage box 4, or multiple sheets curved in this manner may be installed.

[0023] Furthermore, in the above embodiment, the vaporized portion 5c of the vaporizer 5 is positioned above the upper wall portion 41 of the storage box 4, and vapor deposition is performed by a so-called deposit-up type, but the present invention is not limited to this. Referring to Fig. 3(a) in which the same members and elements are given the same reference numerals, a vapor deposition source DS2 of another embodiment includes a box-shaped storage box 40, and a through hole 40b through which a mesh member 50 can be inserted is formed in a side wall portion 40a. The mesh member 50 is formed of a sheet-like material in which narrow spaces 52 (gaps) are formed between the wires 51 over the entire surface thereof, as in the above embodiment, and is composed of a first portion 50a facing the side wall portion 40a of the storage box 40 with a predetermined gap D1 therebetween, a second portion 50b extending parallel to the upper wall portion (not shown) of the storage box 40, which is bent at a substantially right angle from the tip of the first portion 50a and inserted into the through hole 40b, and a third portion 50c extending diagonally downward in the vertical direction from the second portion 50b. A second heating means 6b is disposed between the third portion 50c and the side wall portion 40a of the storage box 40, so that the third portion 50c as the vaporization portion can be heated. In this case, the second heating means 6b can also be used as the first heating means 6a for heating the storage box 40. The substrate Sw is transported in an upright position, and the surface facing the third portion 50c becomes the deposition surface.

[0024] According to the above embodiment, like the above embodiment, a part of the liquefied organic material Ml permeates into the third portion 50c through the second portion 50b by capillary action, and the third portion 50c into which the liquefied organic material Ml has permeated is heated to a predetermined temperature by the second heating means 6b according to the vapor pressure, so that the organic material Ml is vaporized. At this time, the third portion 50c includes a portion extending downward from the upper surface of the container box 40 (in other words, a portion extending downward from the horizontal line), and therefore, when the liquefied organic material Ml permeates into the third portion 50c, gravity is added to the capillary action, so that the liquefied organic material Ml can more reliably permeate into the third portion 50c, which is advantageous.

[0025] Also, referring to Figure 3(b), a deposition source DS3 in yet another embodiment has two box-shaped storage boxes 400a, 400b, and through holes 402a, 402b are formed in the side wall portions 401a, 401b of each storage box 400a, 400b to allow mesh members 5001, 5002 to pass through. As in the above embodiment, each mesh member 5001, 5002 is composed of a sheet-like material in which thin spaces 52 (gaps) are formed between the wires 51 over its entire surface, and is composed of a first portion 500a facing the side wall portions 401a, 401b of each storage box 400a, 400b with a predetermined gap D1 between them, a second portion 500b extending parallel to the upper wall portions (not shown) of the storage boxes 400a, 400b and bent at approximately a right angle from the tip of the first portion 500a to pass through the through holes 402a, 402b, and a third portion 500c extending diagonally downward in the vertical direction from the second portion 500b and parallel to the bottom wall portions 403a, 403b of the storage boxes 400a, 400b, and connected to each other. A second heating means 6b is disposed above the third portion 500c parallel to the bottom walls 403a and 403b, so that the third portion 500c serving as the vaporization portion can be heated. In this case, the substrate Sw is transported below the container boxes 400a and 400b with its deposition surface facing upward. [Explanation of symbols]

[0026] DS1, DS2, DS3... deposition source for vacuum deposition device, Dm... vacuum deposition device, Ms... solid organic material (deposition material), Ml... molten organic material (deposition material), Sw... substrate (substrate to be deposited), 1... vacuum chamber, 4, 40, 400a, 400b... storage box, 40a, 401a, 401b... side wall of storage box, 40b, 402a, 402b... through hole, 41... upper wall of storage box, 41a... slit hole (through hole), 5, 50, 5 001, 5002...mesh member (vaporized body), D1...gap, 5a...immersed portion (part of vaporized body), 5b...penetrated portion (part of remaining part of vaporized body), 5c...vaporized portion (part of remaining part of vaporized body), 50a, 500a...first portion (immersed portion of vaporized body), 50b, 500b...second portion (penetrated portion of vaporized body), 50c, 500c...third portion (vaporized portion of vaporized body), 6a...first heating means, 6b...second heating means.

Claims

1. A deposition source for a vacuum deposition apparatus that is disposed in a vacuum chamber and that evaporates a solid deposition material and deposits the solid deposition material on a deposition target, the deposition source comprising a storage box filled with the deposition material and a first heating means that enables heating of the deposition material in the storage box, a vaporizer, a portion of which is immersed in the deposition material melted in the storage box by heating and the remaining portion of which extends outward from the storage box; The vaporizer is a mesh member having a cylindrical outline with a bottom and inserted into the storage box from above with its opening side leading, and is configured so that when inserted into the storage box, the gap between the outer surface of the mesh member and the inner surface of the storage box is 100 μm or less.The vaporization source for a vacuum vapor deposition apparatus is characterized in that the molten vapor deposition material permeates into the remaining portion by capillary action, and a second heating means is provided to heat and vaporize the vapor deposition material that has permeated into the portion of the remaining portion that forms the bottom of the mesh member and is parallel to the upper wall of the storage box.

2. A deposition source for a vacuum deposition apparatus that is disposed in a vacuum chamber and that evaporates a solid deposition material and deposits the solid deposition material on a deposition target, the deposition source comprising a storage box filled with the deposition material and a first heating means that enables heating of the deposition material in the storage box, a vaporizer, a portion of which is immersed in the deposition material melted in the container by heating and the remaining portion of which extends outward from the container, The vaporizer is composed of a sheet-like mesh member, and the mesh member has a first portion facing the inner surface of the storage box with a gap of 100 μm or less between it and the inner surface of the storage box, a second portion bent from the tip of the first portion located above the vapor deposition material filled in the storage box and extending toward the outside of the storage box, and a third portion extending vertically downward from the second portion, and is configured so that the molten vapor deposition material permeates into the remaining portion by capillary action, and a second heating means is provided for heating and vaporizing the vapor deposition material that has permeated into the third portion.

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