Evaporation source for vacuum evaporation device

Abstract

A deposition source for a vacuum deposition apparatus is provided, in which, when a crucible filled with a deposition material is heated in an induction heating manner, the entire crucible including a lid is in a top heating state. The deposition source (DS1) includes a crucible (4) filled with a deposition material (Vm), a lid (5) that blocks an upper surface opening (4a) of the crucible, and an induction heating coil (6) disposed around the crucible and the lid. An outlet portion (51a) that allows the deposition material vaporized or sublimated by heating to pass through is provided on the lid. A protrusion (52b) having a corner portion is provided on an outer surface of the lid.

Description

Technical Field

[0001] This invention relates to a vapor deposition source for a vacuum vapor deposition apparatus configured in a vacuum chamber for vapor deposition of a material to be vapor-deposited, and more specifically, to a vapor deposition source for heating the vapor deposition material in a crucible by induction heating. Background Technology

[0002] Such a vacuum evaporation deposition apparatus uses a deposition source, for example, as known in Patent Document 1. It comprises: a crucible filled with a deposition material; a lid that blocks the opening on the upper surface of the crucible and is provided with a discharge nozzle (discharge section) that allows the deposition material, which vaporizes or sublimates upon heating, to pass through; and an induction heating coil disposed around the crucible and the lid. Furthermore, when an alternating current is passed through the induction heating coil in a vacuum chamber with a vacuum atmosphere, the crucible or lid is heated by Joule heat generated by the resistance loss of the induced current (eddy current) flowing through it, and the deposition material inside the crucible is heated by heat transfer from the crucible wall or by radiation from the lid.

[0003] Here, when heating the vapor-deposited material inside the crucible, the vapor-deposited material inside the crucible vaporizes or sublimates only from the upper portion facing the discharge nozzle. Therefore, when heating the crucible including the lid, it is preferable that the lid temperature is high, having a temperature gradient that decreases towards the lower end of the crucible (the so-called top-heated state), so that only the upper portion of the vapor-deposited material is effectively heated, without applying excessive heat load to the lower portion of the vapor-deposited material present in the crucible, causing thermal degradation of the vapor-deposited material (in the case of organic materials, thermal decomposition or thermal denaturation, etc.). In this case, although a top-heated state is easily formed in devices using resistance heating methods such as sheathed heaters, in induction heating devices, resistance loss occurs depending on the area opposite the induction heating coil. Therefore, since the crucible with a larger area is preferentially heated, when the entire crucible is heated to bring the upper portion of the vapor-deposited material to the vaporization or sublimation temperature, there is a problem that the lower part of the crucible is overheated (the so-called bottom-heated state).

[0004] Compared to resistance heating devices, induction heating devices offer better heating responsiveness and the advantage of rapid heat dissipation after vapor deposition. Therefore, there is a need to develop an induction heating vapor deposition source capable of maintaining a heated crucible, including the lid, at the top.

[0005] Existing technical documents

[0006] Patent documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2004-134250 Summary of the Invention

[0008] The technical problem that the invention aims to solve

[0009] In view of the above problems, the present invention aims to provide a vapor deposition source for a vacuum vapor deposition apparatus, wherein when a crucible filled with vapor deposition material is heated by induction heating, the crucible, including the lid, is in a top-heated state.

[0010] means of solving technical problems

[0011] To address the aforementioned issues, the present invention provides a vacuum evaporation deposition apparatus with a deposition source disposed within a vacuum chamber for depositing a material. The deposition source comprises: a crucible filled with a deposition substance; a cover that blocks the opening on the upper surface of the crucible; and an induction heating coil disposed around the crucible and the cover. The feature is that the cover has a discharge portion that allows the deposition substance, which vaporizes or sublimates upon heating, to pass through; and protrusions with corners are provided on the outer surface of the cover.

[0012] According to the present invention, when an alternating current is passed through an induction heating coil in a vacuum chamber under a vacuum atmosphere, an induced current (eddy current) flows through the crucible or lid. At this time, by providing a protrusion with corners on the outer surface of the lid, the resistance loss at the corners (edges) of the protrusion increases. In other words, the heat generated is higher when the magnetic flux density acting on the lid is the same as that of the lid material compared to the case without the protrusion. Therefore, the lid can be heated preferentially, making the entire crucible, including the lid, hot at the top. Furthermore, in the present invention, in the case of the "corner" referred to as the protrusion, for example, in the cross-sectional shape of the protrusion along the long side of the crucible, in addition to the case where the protrusion has a rectangular outline, there are also cases where the protrusion has rounded corners (e.g., an oblong outline) to an extent that can increase the resistance loss.

[0013] In this invention, the cover preferably comprises: a cover plate portion having the discharge portion; and a peripheral wall portion erected vertically downward from the outer edge of the cover plate portion; the lower end of the peripheral wall portion is detachably fitted into the upper end of the crucible, and multiple protrusions are provided on the outer surface of the peripheral wall portion in a vertical or circumferential direction. Thus, the outer surface of the peripheral wall portion has a repeatedly concave-convex shape, increasing the distance of the eddy current flow, thereby further increasing the resistance loss and further increasing the heat generation of the cover, ensuring that the entire crucible, including the cover, is reliably heated from the top.

[0014] However, when no protrusions are provided on the lid, in order to set the crucible, including the lid, to a top-heated state, it is considered to set the winding spacing of the induction heating coils around the lid to be smaller than that of the induction heating coils around the crucible, thereby creating a difference in magnetic flux density. However, even so, the final opposing area of ​​the lid opposite the induction heating coils is small, so a top-heated state cannot be formed. In contrast, in this invention, if the winding spacing of the induction heating coils around the lid is set to be smaller than the coil spacing around the crucible, the eddy currents flowing through the crucible are reduced, thus suppressing the heating of the crucible and enabling the entire crucible, including the lid, to be in a top-heated state more reliably. Attached Figure Description

[0015] Figure 1 This is a partial perspective view illustrating the structure of the vacuum evaporation apparatus of this embodiment.

[0016] Figure 2 This is an enlarged cross-sectional view of the vapor deposition source according to the first embodiment of the present invention.

[0017] Figure 3 This is a partially enlarged cross-sectional view of a modified example of the first embodiment of the present invention.

[0018] Figure 4 This is an enlarged cross-sectional view of the vapor deposition source according to the second embodiment of the present invention. Detailed Implementation

[0019] Referring to the accompanying drawings, the following description illustrates the deposition source DS of the deposition apparatus of the present invention, using a glass substrate (hereinafter referred to as "substrate Sw") of a specified thickness with a rectangular outline as the deposition object, and depositing a specified thin film on one side of the substrate Sw. Hereinafter, terms such as "upper" and "lower" are used to indicate directions. Figure 1 This is explained based on the standard.

[0020] Reference Figure 1 Dm is a vacuum evaporation apparatus equipped with the evaporation source DS1 of the first embodiment of the present invention. The vacuum evaporation apparatus Dm includes a vacuum chamber 1. Although not specifically illustrated, a vacuum pump is connected to the vacuum chamber 1 via an exhaust pipe, enabling the vacuum inside the vacuum chamber 1 to be evacuated and maintained at a predetermined pressure (vacuum level). Furthermore, a substrate transport device 2 is provided at the upper part of the vacuum chamber 1. The substrate transport device 2 has a transporter 21 that holds the substrate Sw with its lower surface, which serves as the film-forming surface, open. A drive device (not shown) moves the transporter 21 and the substrate Sw in one direction within the vacuum chamber 1 at a predetermined speed. Since a known device can be used as the substrate transport device 2, further description is omitted. Moreover, multiple evaporation sources DS1 of the first embodiment are arranged side-by-side at intervals along the direction of movement of the substrate Sw on the bottom surface of the vacuum chamber 1.

[0021] Reference Figure 2 Each vapor deposition source DS1 has the same structure, including a bottom cylindrical storage container 3, which is set on the bottom surface of the vacuum chamber 1 with its opening 3a facing upwards. Furthermore, a crucible 4 is housed inside the storage container 3, and an induction heating coil 6 is arranged between the storage container 3 and the crucible 4.

[0022] The crucible 4 has a bottomed cylindrical shape and is disposed on the lower surface of the storage container 3. Furthermore, a lid 5 is detachably mounted on the crucible 4 to block the opening 4a on its upper surface. The lid 5 has: a cover plate portion 51 with multiple openings 51a (discharge portions 51a); and a peripheral wall portion 52 that extends downwards from the outer edge of the cover plate portion 51. An upwardly recessed recess 52a is formed at the lower end of the peripheral wall portion 52. By inserting the upper end of the crucible 4 into this recess 52a, the lid 5 is detachably mounted on the crucible 4 (see reference). Figure 2 The portion enclosed by a dashed line is shown in the diagram. In this case, although not specifically illustrated, protrusions are provided at intervals along the circumference at the upper end of the crucible 4, and each protrusion makes point contact with the recess 52a of the lid 5. The crucible 4 and the lid 5 are made of conductive materials such as carbon, graphite, titanium, SUS, and borides (BN), with a metal film or graphite film treated on the surface of the ceramic material such as borides.

[0023] Furthermore, in Figure 2 In the diagram, the portion enclosed by the dashed line is an enlarged portion of the peripheral wall 52 of the cover 5. Multiple protrusions 52b are formed at equal intervals in the vertical direction on the outer surface of the peripheral wall 52, creating a repeating concave-convex shape. Each protrusion 52b is formed, for example, by countersinking the peripheral wall 52 to create a rectangular profile that is continuous across its entire circumference. The number of protrusions 52b, the height h of each protrusion 52b from the outer surface of the peripheral wall 52, and the vertical width w are appropriately set considering factors such as the temperature of the heated vapor-deposited material Vm, the area of ​​the peripheral wall 52, the distance from the electromagnetic induction coil 6 (without contact with the electromagnetic induction coil 6), and machinability. For example, the height h is set to 100 μm or more, and the width w is set in the range of 0.1 to 10 mm.

[0024] An inner crucible portion 41 is stored inside the crucible 4. The inner crucible portion 41 is made of a material with heat resistance and low thermal conductivity, such as ceramic, titanium, or SUS. Then, a vapor deposition material Vm is filled into the inner crucible portion 41. As the vapor deposition material Vm, an organic material is appropriately selected according to the thin film to be formed on the substrate Sw, and a particulate or sheet-like material is used. In this embodiment, the case of having an inner crucible portion 41 and filling the inner crucible portion 41 with vapor deposition material Vm is described as an example, but it is also possible to not provide an inner crucible portion 41 inside the crucible 4, but instead fill the crucible 4 with vapor deposition material Vm.

[0025] An induction heating coil 6, wound at a predetermined spacing to cover the entire circumference of the crucible 4 and the lid 5, is electrically connected to an AC power source (not shown). When an AC current is applied to the induction heating coil 6 within a vacuum chamber 1 in a vacuum atmosphere, the crucible 4 or lid 5 is heated by the Joule heat generated by the resistance loss of the induced current (eddy current) flowing through it. In this embodiment, the winding spacing of the induction heating coil 6 is set such that Ph1 around the lid 5 is smaller than Ph2 around the crucible 4.

[0026] Based on the above, when a specified organic film is deposited on the lower surface of the substrate Sw using the aforementioned vacuum evaporation apparatus Dm, if an AC power supply is applied to the induction heating coil 6 within the vacuum chamber 1 in a vacuum atmosphere, an induced current (eddy current) flows through the crucible 4 and the cover 5. At this time, by providing protrusions 52b with corners on the outer surface of the cover 5, the resistance loss at the corners (edges) of the protrusions 52b increases, and the heat generation is higher than when the magnetic flux density acting on the cover 5 is the same as that of the cover 5, compared to the case where no protrusions 52b are provided. Therefore, the cover 5 can be heated preferentially, resulting in the entire crucible, including the cover 5, being in a top-heated state.

[0027] Furthermore, according to the present invention, by providing multiple circumferentially extending protrusions 52b on the outer surface of the peripheral wall portion 52 of the cover body 5, the distance of the eddy current flow is lengthened, thereby further increasing the resistance loss and increasing the heat generation of the cover body 5, so that the entire crucible including the cover body 5 is reliably in a top-heated state. Moreover, by setting the winding spacing Ph1 of the induction heating coil 6 located around the cover body 5 to be smaller than the spacing Ph2 located around the crucible 4, the eddy current flowing through the crucible 4 is reduced, thus suppressing the heating of the crucible 4 and more reliably ensuring that the entire crucible including the cover body 5 is in a top-heated state.

[0028] To confirm the above effects, the following evaluation was performed using the aforementioned vapor deposition source DS1. Specifically, a titanium crucible 4 and a lid 5 were used. Multiple protrusions 52b were provided circumferentially on the peripheral wall 52 of the lid 5. The height h of these protrusions from the outer surface of the peripheral wall 52 was 100 μm, and the width w in the vertical direction was 2.0 mm. The resistance loss of the crucible 4 and lid 5 was evaluated. At this time, the winding pitch Ph1 of the induction heating coil 6 surrounding the lid 5 was set to 10 mm, and the winding pitch Ph2 of the induction heating coil 6 surrounding the crucible 4 was set to 30 mm. A 20 A current was applied at a frequency of 200 kHz. Additionally, a device without protrusions on the peripheral wall of the lid 5 was used as a comparative experiment to evaluate the resistance loss of the crucible 4 and lid 5.

[0029] In the comparative experiment, the resistance loss of crucible 4 was 8.4 W / m. 3The resistance loss of cover 5 is 4.2 W / m. 3 The resistance loss of the lid 5 is smaller than that of the crucible 4. Conversely, in the invention experiments, the resistance loss of the crucible 4 was confirmed to be 3.2 W / m. 3 The resistivity loss of cover 5 is 8.6 W / m. 3 The resistance loss of the cover 5 is greater than that of the crucible 4, and it is in a top-heated state.

[0030] The embodiments of the present invention have been described above, but various modifications can be made without departing from the technical concept of the present invention. In the first embodiment of the vapor deposition source DS1 described above, a structure in which multiple protrusions 52b are provided circumferentially on the outer surface of the peripheral wall portion 52, and the cross-sectional shape of the protrusions 52b in the vertical direction (long side direction of the crucible 4) has a rectangular outline has been described as an example. However, the position of the protrusions 52b is not limited to this. For example, the protrusions can also be provided on the outer surface of the cover plate portion 51. Furthermore, the shape of the protrusions is not limited to this. As long as it can increase the resistance loss when the induced current (eddy current) flows and has a certain length, it is acceptable. For example, the shape of the protrusions 52b can also be a cross-sectional shape with rounded corners to increase the resistance loss.

[0031] That is, if the same parts or elements are labeled with the same reference numerals in the accompanying drawings. Figure 3 As shown in (a) and (b), in the vapor deposition source involved in the modified example, the cross-sectional shape of the protrusion can also be an oblong shape with rounded corners to the extent that the resistance loss increases. Figure 3 (a) 52c), the cross-section with the chamfered surface is approximately pentagonal in shape. Figure 3 (b) The protrusions 52d). Even the shape of these corners makes the outer surface of the peripheral wall 52 have a repeating concave-convex shape, which increases the resistance loss due to the longer distance of the eddy flow and can increase the heat generation of the cover 5.

[0032] Furthermore, in the vapor deposition source DS1 of the first embodiment described above, an example was given where multiple protrusions 52b extend circumferentially along the peripheral wall portion 52; however, the pattern of the protrusions is not limited to this. Refer to the accompanying drawings where the same reference numerals are used to label the same parts or elements. Figure 4 In the vapor deposition source DS2 according to the second embodiment, multiple protrusions are provided in a manner in which each protrusion 52e extends along the vertical direction of the peripheral wall portion 52. Furthermore, in Figure 4 In the image, the portion enclosed by the dotted line is an enlarged view of the peripheral wall portion 52 of the cover 5 as viewed from above. Alternatively, it can be arranged in a grid pattern where the protrusions 52b extending circumferentially intersect with the protrusions 52e extending vertically, or in a spiral pattern around the generatrix of the peripheral wall portion 52.

[0033] Furthermore, in the first embodiment described above, the example was given where the winding pitch of the induction heating coil 6 was set such that Ph1 around the cover 5 was smaller than Ph2 around the crucible 4. However, this is not a limitation. The winding pitch of the induction heating coil 6 can also be set such that the induction heating coil around the cover 5 and the induction heating coil around the crucible 4 have the same winding pitch.

[0034] Explanation of reference numerals in the attached figures

[0035] Dm. Vacuum vapor deposition apparatus, DS1, DS2. Vapor deposition source, Sw. Substrate (substrate to be vaporized), Vm. Vapor deposition material, 1. Vacuum chamber, 4. Crucible, 4a. Upper surface opening, 5. Cover, 51. Cover plate portion, 51a. Discharge portion, 52. Peripheral wall portion, 52b~52e. Protrusions, 6. Induction heating coil, Ph1. Winding spacing of the induction heating coil located around the cover, Ph2. Winding spacing of the induction heating coil located around the crucible.

Claims

1. A vapor deposition source for a vacuum vapor deposition apparatus, disposed within a vacuum chamber for vapor deposition of an object to be vapor-deposited, the vapor deposition source comprising: A crucible filled with vapor-deposited material; a lid that blocks the opening on the upper surface of the crucible; and an induction heating coil disposed around the crucible and the lid. Its features are: The cover is provided with a discharge section that allows vaporized or sublimated deposited material to pass through. The cover includes: a cover plate portion having the discharge portion; and a peripheral wall portion erected vertically downward from the outer edge of the cover plate portion; the lower end of the peripheral wall portion is detachably fitted into the upper end of the crucible, and multiple protrusions with corner portions are provided on the outer surface of the peripheral wall portion in a manner extending in the vertical or circumferential direction.

2. The vapor deposition source for the vacuum vapor deposition apparatus according to claim 1, characterized in that: The winding spacing of the induction heating coils located around the cover is set to be smaller than the coil spacing located around the crucible.

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