Evaporation source for vacuum deposition apparatus

Abstract

To provide a vapor deposition source for a vacuum deposition apparatus which enables direct replenishment of a deposition material without atmospheric exposure of a vacuum chamber, where the deposition is performed, while maintaining stable deposition rates even after replenishment.SOLUTION: The present invention provides a vapor deposition source DS1 for a vacuum deposition apparatus Dm1 that causes a deposition material Ms within a storage box 4, vaporized or sublimated by heating means Mt, to be released from a release part 42 and then deposited onto a target to be deposited Sw in a vacuum chamber 1. Above the storage box, a communication room 2a, 31 with a first opening-closing door 5a and a material storage room 6a are provided to enable the formation of a vacuum atmosphere. The material storage room is provided with a chute 71 with a part 71a projecting into the communication room, an input port 61 that enables the injection of the deposition material into the material storage room, a second opening-closing door 5b that closes the input port in a freely openable manner, and a delivery screw 72 that extends vertically, passing through the chute. The portion of the delivery screw projecting from the chute is provided with a diffuser 8a which extends slanting downwards in the vertical direction.SELECTED DRAWING: Figure 1

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 vaporizes or sublimates an evaporation material to deposit it on a deposition object. More specifically, the present invention relates to an evaporation source that enables the supply of an evaporation material without returning the inside of the vacuum chamber to an atmospheric atmosphere.

Background Art

[0002] For example, in the manufacturing process of an organic EL element, there is a step of vaporizing or sublimating a solid evaporation material (organic material) such as α-NPD or 2-TNATA on a substrate as a deposition object in a vacuum atmosphere to deposit a predetermined thin film on the surface of the deposition object. In general, a vacuum evaporation apparatus is used for the evaporation step. As an evaporation source used in such a vacuum evaporation apparatus, a rectangular parallelepiped housing box for housing an evaporation material is provided, and a slit-shaped discharge portion is provided on the opposing surface (i.e., the upper surface in the vertical direction) to the sheet-shaped base material portion of the housing box (so-called line source: see, for example, Patent Document 1). When depositing on a deposition object, after the ingot-shaped or granular evaporation material is housed in the housing box, the evaporation material in the housing box is heated (e.g., 300°C) by heating means in a vacuum atmosphere to be vaporized or sublimated (hereinafter simply referred to as "sublimation"). Then, the sublimated material is discharged from the discharge opening due to the pressure difference with the inside of the vacuum chamber, and a predetermined thin film is deposited (formed) on the surface of the deposition object.

[0003] By the way, when the deposition material contained in the storage box is sublimated by heating, the amount of deposition material itself decreases as a result, so it is necessary to replenish the deposition material periodically. In this case, if the deposition material can only be replenished in the storage box while the film formation process is stopped and the vacuum chamber is returned to an atmospheric environment, productivity will be severely impaired. Therefore, the following deposition source for a vacuum deposition apparatus is known, for example, in Patent Document 2. This apparatus comprises a sublimation container located outside the vacuum chamber, filled with an organic material and having a heating means, and a diffusion container located inside the vacuum chamber, which diffuses the sublimated deposition material inside and has a discharge section (passage) formed therein for releasing the diffused material, and the two containers are connected to each other by a connecting pipe of a predetermined length with a flow control valve interposed between them.

[0004] In the conventional example described above, closing the flow control valve allows for atmospheric separation between the vacuum chamber and the sublimation vessel, making it possible to replenish the deposition material without specifically opening the vacuum chamber to the atmosphere. However, since the deposition material sublimated in the sublimation vessel is supplied through a relatively long connecting pipe, there is a risk that the film formation (deposition) rate may fluctuate and become unstable due to pressure loss, etc. Furthermore, a mechanism is needed to heat the connecting pipe to a temperature above the vaporization temperature or sublimation temperature to prevent the deposition material adhering to the inner surface from liquefying or solidifying. For these reasons, a configuration that allows for direct replenishment of the deposition material into a storage box with a discharge section is desirable. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2014-77193 [Patent Document 2] Japanese Patent Publication No. 2015-63724 [Overview of the project] [Problems that the invention aims to solve]

[0006] In view of the above, the object of the present invention is to provide a deposition source for a vacuum deposition apparatus that allows direct replenishment of deposition material without opening the vacuum chamber in which deposition is performed to the atmosphere, and that does not impair the stability of the film deposition rate even after replenishment. [Means for solving the problem]

[0007] To solve the above problems, the present invention provides a vapor deposition source for a vacuum deposition apparatus comprising a storage box filled with a vapor deposition material and a heating means for heating the storage box, wherein the vapor deposition material in the storage box is vaporized or sublimated by the heating means, and the vaporized or sublimated vapor deposition material is released from a discharge section formed in the storage box to be deposited on an object to be deposited in a vacuum chamber, wherein a communication chamber having a first opening / closing door and a material storage chamber are provided on the vertically upper side of the storage box in a manner that allows for the formation of a vacuum atmosphere, the material storage chamber is provided with a chute that partially protrudes into the communication chamber, an inlet that allows the vapor deposition material to be introduced into the material storage chamber, a second opening / closing door that can open and close the inlet, and a discharge screw that extends vertically through the chute, and a diffusion member that extends downward with respect to the vertical direction is provided on the portion of the discharge screw that protrudes from the chute. In this case, a configuration in which a dispersion member is provided in the communication chamber at a position below the lower end of the discharge screw may also be adopted.

[0008] According to the above, the first opening / closing door is closed, separating the atmosphere of the storage box and the material storage chamber, and the material storage chamber is then exposed to atmospheric air. In this state, the second opening / closing door is opened, and the material storage chamber is filled with the deposition material at a predetermined filling rate. At this time, for example, if the gap between the helical teeth of the delivery screw and the chute is appropriately set, the deposition material can be retained in the chute (especially sublimable organic materials, which are prone to aggregation and therefore easier to retain), and falling into the communication chamber can be prevented as much as possible. Once the deposition material is filled, the second opening / closing door is closed to maintain airtightness in the material storage chamber, and then the inside is evacuated to a predetermined pressure using a vacuum pump, putting it into a standby state. This series of operations can be performed while deposition is taking place on the object to be deposited in the vacuum chamber.

[0009] When filling a storage box with deposition material in a vacuum atmosphere equivalent to that of a vacuum chamber, the first opening / closing door is opened to connect the material storage chamber and the storage box via a communication chamber. In this state, the delivery screw is rotated at a predetermined speed around its shaft. As a result, the deposition material in the chute is sequentially delivered, and the deposition material is scattered circumferentially by the diffusion member, making it possible to deposit (fill) the deposition material evenly over the entire bottom surface of the storage box. In this case, if a dispersion member is provided (the dispersion member itself may be made to vibrate), it will be possible to deposit the deposition material evenly.

[0010] However, if the deposition material is simply dropped into the storage box via a chute, the deposition material will accumulate on the bottom surface of the storage box in a mound-like shape. In this case, if the deposition material is, for example, a sublimable material, sublimation will only occur from the surface portion of the deposited deposition material, resulting in a lower sublimation rate per unit time when the same amount of heat is applied, and consequently, an unstable film deposition rate. In contrast, in the present invention, even if the deposition material is repeatedly replenished, the deposition material is always deposited evenly over the entire bottom surface of the storage box, and the surface area of ​​this deposited deposition material can be kept approximately constant at all times. Thus, in the present invention, the deposition material can be replenished without specifically opening the vacuum chamber to the atmosphere. Furthermore, when the first opening / closing door is closed and deposition in the vacuum chamber is restarted (after replenishing the deposition material), the deposition material is evenly filled over the entire bottom surface of the storage box, making it less likely for the stability of the film deposition rate to be compromised. [Brief explanation of the drawing]

[0011] [Figure 1] A partially enlarged cross-sectional view of a vacuum deposition apparatus equipped with a deposition source according to an embodiment of the present invention. [Figure 2] (a) and (b) are plan and cross-sectional views illustrating the distributed members. [Figure 3] Figure 1 illustrates the supply state of the deposition material at the deposition source shown. [Figure 4] A schematic cross-sectional view showing a vacuum deposition apparatus equipped with a deposition source according to a modified example. [Figure 5] A partial perspective view showing a modified example of the dispersed member. [Modes for carrying out the invention]

[0012] The embodiments of the deposition source for the vacuum deposition apparatus of the present invention will be described below with reference to the drawings, using as an example the case in which a predetermined organic film is deposited (deposited) on a substrate Sw in an upright position with the film deposition surface facing horizontal. In the following, terms indicating directions such as "up" and "down" will be based on Figure 1, which shows the installation position of the deposition source in the vacuum chamber.

[0013] Referring to Figure 1, the vacuum deposition apparatus Dm1 equipped with the deposition source DS1 of this embodiment is a so-called side-deposit type and includes a vacuum chamber 1 in which a substrate Sw, which is to be deposited, is placed. Although not specifically shown and described, a vacuum pump is connected to the vacuum chamber 1 via an exhaust pipe, and a vacuum atmosphere can be formed by evacuating to a predetermined pressure (vacuum level). A storage chamber 2 is provided on the outer wall of the vacuum chamber 1, and the deposition source DS1 of this embodiment is placed inside the storage chamber 2. Inside the storage chamber 2, the atmosphere is separated into upper and lower chambers 2a and 2b by a partition plate 3 made of a heat-resistant and low thermal conductivity material, and a housing box 4 having an opening 41 on its upper surface is attached to the lower surface of the partition plate 3, and together with heating means Ht arranged around the housing box 4, the deposition source DS1 is formed.

[0014] The storage box 4 is made of a material with good thermal conductivity and a high melting point (having heat resistance), such as stainless steel (SUS304, etc.), titanium, tantalum, tungsten, molybdenum, or carbon. A cylindrical discharge section 42 having a discharge passage 42a is provided on the side of the storage box 4, and the discharge section 42 is fitted into mounting holes 11 and 21 formed in the vacuum chamber 1 and the storage chamber 2, respectively. As the heating means Ht, known types such as sheath heaters and lamp heaters can be used, or it can be made of an induction heating coil. The partition plate 3 has a communication hole 31 that penetrates vertically and coincides with the contour of the opening 41, and a first opening / closing door 5a is provided that closes the communication hole 31 from above. As the first opening / closing door 5a, known types such as sliding or swinging doors can be used. In its closed position, it separates the atmosphere between the upper chamber 2a within the storage chamber 2, which is located above the first opening / closing door 5a, and the inside of the storage box 4. In its open position, a communication chamber is formed by the communication hole 31 and the upper chamber 2a.

[0015] A material storage chamber 6 is connected to the upper side of the storage chamber 2, defining a material storage chamber 6a for storing replenishment organic material Ms. A vacuum pump Pu is connected to both the storage chamber 2 and the material storage chamber 6 via an exhaust pipe Pp, allowing them to be evacuated to a predetermined pressure. An inlet 61 for introducing organic material Ms is provided on the upper wall of the material storage chamber 6, and a second opening / closing door 5b is provided to close the inlet 61 from above. Similar to the first opening / closing door 5a, a known type such as a sliding door or a swinging door can be used for the second opening / closing door 5b, and in its closed position, it maintains airtightness inside the material storage chamber 6a. A material storage supply unit 7 is located inside the material storage chamber 6a.

[0016] The material storage and supply unit 7 comprises a chute 71 fixedly positioned within the material storage chamber 6a and a delivery screw 72 positioned within the chute 71. The chute 71 has a funnel-shaped contour, and its cylindrical delivery section 71a, located at its lower end, is formed in the wall portion separating the storage chamber 2 and the material storage chamber 6, and protrudes into the upper chamber 2a by being inserted through a through hole 22 having the same hole axis Ha as the communication hole 31. The delivery screw 72 has a rotating shaft 72a that can rotate around the hole axis Ha, and helical teeth 72b formed at equal pitches around the rotating shaft 72a, and the portion of the helical teeth 72b located within the delivery section 71a is designed to be inserted into the inner surface of the delivery section 71a with a predetermined gap. As a result, when organic material Ms is filled, the organic material Ms is retained within the chute 71 (especially sublimable organic material Ms is easily retained due to its cohesive nature), and its fall into the upper chamber 2a is suppressed as much as possible.

[0017] The rotating shaft 72a is supported by a bearing 72d of a support frame 72c provided in the material storage chamber 6a. A pulley 72e is attached to the upper end of the rotating shaft 72a. A belt Mv is wrapped between the pulley 72e and a pulley 72f attached to the rotating shaft Ma of a drive motor Mt located on the upper wall of the material storage chamber 6. When the motor Mt is rotated, the delivery screw 72 is rotated at a predetermined speed. In addition, a diffusion member 8a, which is a plate-shaped member of a predetermined area that extends downward inclined in the vertical direction, is attached to the portion of the rotating shaft 72a that protrudes downward from the delivery section 71a. The diffusion member 8a rotates around the hole axis Ha as the rotating shaft 72a rotates, and plays a role in distributing the organic material Ms delivered from the delivery section 71a in the circumferential direction.

[0018] Below the delivery section 71a within the upper chamber 2a, a dispersion member 8b with a plate-like profile and a predetermined area is arranged facing the communication hole 31. As shown in FIGS. 2(a) and (b), the dispersion member 8b is made of a heat-resistant material such as stainless steel (SUS304, etc.), titanium, tantalum, tungsten, molybdenum, or carbon, and is composed of wire rods 81a, 81b with a cylindrical or prismatic profile assembled in a lattice pattern so that a rectangular mesh 82 is formed. Further, a truncated cone 83 that expands in diameter downward is provided on the lower surface of the portion of the dispersion member 8b located at the intersection of each wire rod 81a, 81b. This serves to further disperse the organic material Ms sent out from the delivery section 71a and diffused by the diffusion member 8a and send it into the storage box 4. Hereinafter, referring also to FIG. 3, the replenishment of the material Ms by the material storage supply unit 7 will be described.

[0019] Close the first opening / closing door 5a to separate the storage box 4, the upper chamber 2a, and the material storage chamber 6a from the atmosphere, and set the upper chamber 2a and the material storage chamber 6a to the atmospheric atmosphere. In this state, open the second opening / closing door 5b and fill the chute 71 in the material storage chamber 6a with the organic material Ms at a predetermined filling rate. At this time, for example, due to the gap between the spiral teeth 72b of the delivery screw 72 and the chute 71, the organic material Ms is retained in the chute 71 (particularly, since the sublimable organic material Ms has cohesion, it is easily retained), and the fall into the upper chamber 2a can be prevented as much as possible. When the organic material Ms is filled, close the second opening / closing door 5b to keep the upper chamber 2a and the material storage chamber 6a airtight, and then evacuate their interiors to a predetermined pressure by the vacuum pump Pu and set it to the standby state. These series of operations can be carried out during the vapor deposition on the substrate Sw within the vacuum chamber 1.

[0020] When filling the organic material Ms into the storage box 4 in a vacuum atmosphere equivalent to that of the vacuum chamber 1, the film formation is once stopped (that is, the heating by the heating means Ht is stopped, and the evacuation in the vacuum chamber 1 is maintained). Then, the first opening / closing door 5a is opened to communicate the upper chamber 2a and the material storage chamber 6a through the communication hole 31 with the storage box 4. In this state, the driving motor Mt rotates the feed screw 72 around its rotation axis 72a at a predetermined rotational speed (for example, 5 rpm to 100 rpm). Then, the organic material Ms in the chute 71 is sequentially fed out, and the organic material Ms is scattered in the circumferential direction by the diffusion member 8a and further dispersed by the dispersion member 8b (in this case, the mesh member 8b itself may be vibrated), so that the organic material Ms is evenly deposited over the entire bottom surface of the storage box 4. When all the organic material Ms in the chute 71 is fed out into the storage box 4, after stopping the driving motor Mt, the first opening / closing door 5a is closed again, and the heating by the heating means Ht is restarted. At the same time, the upper chamber 2a and the material storage chamber 6a are returned to the atmospheric atmosphere, and according to the above, the organic material Ms to be replenished next is prepared.

[0021] According to the above, even if the replenishment of the organic material Ms is repeated, the organic material Ms is always evenly deposited over the entire bottom surface of the storage box 4, and the area of the surface portion of the deposited organic material Ms can be kept substantially constant at all times. Thereby, the organic material Ms can be replenished without particularly opening the vacuum chamber 1 to the atmosphere. And since the organic material Ms is evenly filled over the entire bottom surface of the storage box 4, even when the film formation (evaporation) is restarted in the vacuum chamber 1 after closing the first opening / closing door 5a (after replenishing the organic material Ms), it is possible to make it difficult to impair the stability of the film formation rate.

[0022] Although embodiments of the present invention have been described above, various modifications are possible as long as they do not deviate from the technical concept of the present invention. In the above embodiments, an example was described in which the organic material Ms is retained in the chute 71 in the gap between the helical teeth 72b and the inner surface of the delivery section 71a, but the invention is not limited thereto, and for example, a cover plate (not shown) may be provided below the helical teeth 72b. Also, in the above embodiments, an example was described in which a storage box 4 is placed in a storage chamber 2 connected to a vacuum chamber 1 in which vacuum deposition is performed, and film deposition (deposition) is performed in a so-called side deposit manner, but the invention is not limited thereto, and in the above embodiments, an example was described in which the chute 71 is fixedly positioned, but the invention is not limited thereto.

[0023] As shown in Figure 4, where the same components and elements are denoted by the same reference numerals, in the vacuum deposition apparatus Dm2 equipped with the deposition source DS2 according to the modified example, film deposition is possible using the so-called deposit-up method, and the chute 71 is configured to be movable. Specifically, at the bottom of the vacuum chamber 10 of the vacuum deposition apparatus Dm2, a locally bulging space 10a is provided in a direction perpendicular to the vertical direction, and a housing box 40 is arranged within the bulging space 10a. On the side of the housing box 40, a cylindrical body 40a is provided that extends along the processing surface of the substrate Sw (to the right in Figure 4), and a plurality of discharge nozzles 40b are provided on the upper surface of the cylindrical body 40a at intervals. In this case, it is desirable to configure the heating means Ht so that the cylindrical body 40a can also be heated independently.

[0024] The upper wall portion 10b of the vacuum chamber 10 that defines the bulging space 10a is made of a heat-resistant and low thermal conductivity material, and a communication hole 101 is provided in the center of the upper wall portion 10b that penetrates vertically and coincides with the contour of the opening 41, forming a communication chamber. A first opening / closing door 5a is provided to close the communication hole 101 from above. A storage chamber 20 is connected to the upper wall portion 10b of the vacuum chamber 10, and a material storage and supply unit 70 is provided inside it. The material storage and supply unit 70 has a material storage container 701 which consists of a substantially cylindrical container body 701a and a chute 701b provided continuously on the lower surface of the container body 701a, and partitions the material storage chamber 701c. A delivery screw 72 is inserted inside the material storage container 701. In this case, a lid plate 701d is attached to the top opening of the container body 701a, and the rotating shaft 72a of the delivery screw 72 is connected to a drive motor Mt provided on the lid plate 701d. The rotating shaft 72a is pivotally supported by a bearing 701e of the lid plate 701d. A lifting mechanism 90, for example composed of a single-axis robot, is provided inside the storage chamber 20, which can move the material storage container 701 up and down by a predetermined stroke value. An inlet 201 for introducing organic material Ms into the material storage container 701 is provided on the upper wall of the storage chamber 20, and a second opening / closing door 5b is provided to close the inlet 201 from above.

[0025] According to the above, the first opening / closing door 5a is closed, separating the atmosphere of the storage box 40 and the material storage chamber 701c, and the material storage chamber 701c is made to an atmospheric environment. In this state, the second opening / closing door 5b is opened, and the material storage container 701 is filled with organic material Ms at a predetermined filling rate, for example, manually. Once the organic material Ms is filled, the second opening / closing door 5b is closed to maintain airtightness of the material storage chamber 701c, and then the inside is evacuated to a predetermined pressure using a vacuum pump Pu (not shown), and the chamber is put into a standby state. These series of operations can be carried out during deposition on the substrate Sw in the vacuum chamber 10, as described above. When filling the storage box 4, which is in a vacuum atmosphere equivalent to that of the vacuum chamber 10, with organic material Ms is temporarily stopped (i.e., heating by the heating means Ht is stopped, and the vacuum evacuation in the vacuum chamber 10 is maintained). Then, the first opening / closing door 5a is opened to connect the material storage chamber 701c and the storage box 40 through the communication hole 11.

[0026] Next, the lifting mechanism 90 lowers the material storage container 701 to a height where the lower end of the chute 701b enters the storage box 40. Then, the drive motor Mt is rotated, causing the delivery screw 72 to rotate around its rotation axis 72a at a predetermined speed. As a result, the organic material Ms in the chute 701b is sequentially delivered, and the organic material Ms is scattered circumferentially by the diffusion member 8a, so that the organic material Ms is evenly deposited over the entire bottom surface of the storage box 40. Once all the organic material Ms in the chute 701b has been delivered into the storage box 40, the drive motor Mt is stopped, and the lifting mechanism 90 raises the material storage container 701 to a height where the lower end of the chute 701b is located inside the material storage chamber 701c. Then, the first opening / closing door 5a is closed again, and heating by the heating means Ht is resumed. At the same time, the material storage chamber 701c is returned to an atmospheric environment, and the next batch of organic material Ms to be replenished is prepared according to the above procedure.

[0027] Furthermore, in the above embodiment, the dispersion member 8b was described as an example in which cylindrical or prismatic wires 81a, 81b are assembled in a grid pattern and a truncated cone 83 is provided. However, it is not limited to this as long as it can further disperse the organic material Ms scattered circumferentially by the diffusion member 8a. For example, as shown in Figure 5, the dispersion member 80 may be constructed by assembling multiple V-shaped angle members 80a, 80b in a grid pattern with their vertices facing upwards. In this case, the truncated cone 83 can be omitted. [Explanation of Symbols]

[0028] DS1, DS2... Evaporation source, Dm1, Dm2... Vacuum evaporation apparatus, Ht... Heating means, Ms... Organic material (evaporation material), Sw... Substrate (object to be evaporated), 1, 10... Vacuum chamber, 2a... Upper chamber (communication chamber), 31, 101... Communication hole (communication chamber), 4, 40... Storage box, 42... Discharge section, 5a... First opening / closing door, 5b... Second opening / closing door, 6a, 701c... Material storage chamber, 61... Input port, 71, 701b... Chute, 72... Discharge screw, 8a... Diffusion member, 8b, 80... Dispersion member.

Claims

1. A vapor deposition source for a vacuum deposition apparatus comprises a container filled with a deposition material and a heating means for heating the container, wherein the heating means vaporizes or sublimes the deposition material in the container, and the vaporized or sublimated deposition material is released from a discharge section formed in the container to deposit onto an object to be deposited in a vacuum chamber, A communication chamber with a first opening / closing door and a material storage chamber for replenishment deposition materials are provided on the vertically upper side of the storage box, in a state where a vacuum atmosphere can be formed. The material storage chamber is provided with a chute that partially protrudes into the communication chamber, an inlet that allows the loading of replenishment deposition material into the material storage chamber, a second opening / closing door that can be opened and closed to close the inlet, and a discharge screw that extends vertically through the chute. A diffusion member is provided on the portion of the discharge screw that protrudes from the chute, which is inclined downward in the vertical direction. The deposition source for a vacuum deposition apparatus is characterized in that the discharge screw sequentially discharges replenishment deposition material from the chute by its rotational drive, and the diffusion member is configured to diffuse the replenishment deposition material in the circumferential direction.

2. The deposition source for a vacuum deposition apparatus according to claim 1, characterized in that a dispersion member is provided in the communication chamber positioned below the lower end of the delivery screw.

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