Vapor deposition boat and vacuum vapor deposition apparatus including the same

Abstract

To provide a vapor deposition boat that can suppress deterioration in yield of products due to splash even in high-speed film deposition, and to provide a vacuum vapor deposition apparatus including the same.SOLUTION: A vapor deposition boat includes a boat body, an electrode fitting part, and a cavity part. The boat body is formed of a plate-like resistance heating body which is longitudinal in a uniaxial direction. The electrode fitting part is installed to both ends in a longitudinal direction of the boat body. The cavity part can store a vapor deposition material, is formed at one surface of the boat body, and has a planar shape which is rectangular and longitudinal in the uniaxial direction. The boat body has a length of 60 mm or less in a width direction orthogonal to the uniaxial direction. The cavity part has a length of 22 mm or more and 51 mm or less in a width direction orthogonal to the uniaxial direction.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a deposition boat used for resistance heating deposition and a vacuum deposition apparatus equipped with the same. [Background technology]

[0002] Conventionally, vacuum deposition techniques have been known in which a metal or the like is evaporated under a reduced pressure environment to form a thin film on a film or the like. As a deposition source for this type of vacuum deposition apparatus, for example, a so-called resistance heating type deposition source is known, which includes a deposition boat having a storage section for the deposition material and a material supply means for supplying wire-shaped deposition material to the deposition boat, and which heats the deposition boat to evaporate the deposition material into the storage section (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 7404582 Summary of the Invention [Problem to be solved by the invention]

[0004] In vacuum deposition systems equipped with resistance-heated deposition sources, it is necessary to maintain a stable deposition rate while suppressing a decrease in product yield due to splashing (boiling). In particular, in recent years, there has been an increasing demand for faster film formation speeds to improve productivity, and the current supplied to the deposition boat is increasing to increase the evaporation rate of the deposition material. However, the frequency of splashing varies greatly depending on the melting rate and amount of molten metal of the deposition material in the deposition source, and no technology has yet been established to effectively suppress splashing.

[0005] In view of the above circumstances, an object of the present invention is to provide a deposition boat that can suppress a decrease in product yield due to splash even during high-speed film formation, and a vacuum deposition apparatus equipped with the same. [Means for solving the problem]

[0006] An evaporation boat according to one aspect of the present invention includes a boat body, an electrode attachment portion, and a cavity portion. The boat body is formed of a plate-shaped resistance heater that is elongated in one axial direction. The electrode attachment portions are provided at both longitudinal ends of the boat body. The cavity portion is capable of containing a deposition material, is formed on one surface of the boat body, and has a rectangular shape in plan view that is elongated in the uniaxial direction. The length of the boat body in a width direction perpendicular to the axial direction is 60 mm or less, The length of the cavity in the width direction perpendicular to the axial direction is 22 mm or more and 51 mm or less.

[0007] By setting the width dimensions of the boat body and the cavity portion to the above values, the occurrence of splashes can be suppressed even during high-speed film formation.

[0008] The cavity may have a depth of 1 mm or less.

[0009] The cavity portion may include a pair of inclined surfaces that are inclined upward from both side portions in the width direction toward a center portion in the width direction.

[0010] The height of the pair of inclined surfaces may be 1 mm or more and 10 mm or less.

[0011] The electrode attachment portion may have an electrode placement portion formed by cutting out the other surface of the boat body from the end portions toward the center of the boat body in the longitudinal direction.

[0012] When viewed in the thickness direction of the boat body, an overlapping area between both ends of the cavity in the longitudinal direction and the electrode placement portion may be 10 mm or less. [Effects of the Invention]

[0013] According to the present invention, it is possible to suppress a decrease in product yield due to splash even during high-speed film formation. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a vacuum deposition apparatus according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic perspective view showing a configuration of a vapor deposition source in the vacuum vapor deposition apparatus. [Figure 3] FIG. 2 is a schematic cross-sectional side view of the vapor deposition source. [Figure 4] FIG. 2 is a schematic cross-sectional side view showing an example of the shape of molten metal in a deposition boat. [Figure 5] FIG. 5 is a schematic diagram of a vapor deposition source for explaining the principle of splash generation in FIG. [Figure 6] FIG. 10 is a schematic cross-sectional side view showing another example of the shape of the molten metal in the deposition boat. [Figure 7] FIG. 7 is a schematic diagram of a vapor deposition source for explaining the principle of splash generation in FIG. [Figure 8] 1 is a perspective view showing an entire deposition boat according to a first embodiment of the present invention. [Figure 9] FIG. 2 is a plan view of the evaporation boat. [Figure 10] FIG. 10 is a cross-sectional view taken along line AA in FIG. [Figure 11] 10 is a simulation result showing a temperature distribution in the boat body when the evaporation boat is electrically heated. [Figure 12] FIG. 11 shows the results of an experiment showing the relationship between the temperature difference between the end of the cavity and a predetermined portion on the top surface of the boat body, and the boat width. [Figure 13] FIG. 2 is a schematic diagram showing an example of the distribution of molten metal and slag in a cavity. [Figure 14] FIG. 2 is a diagram illustrating the Lorentz force acting on the molten metal in the cavity. [Figure 15] FIG. 4 is a perspective view showing a configuration of a deposition boat according to a second embodiment of the present invention. [Figure 16]FIG. 2 is a plan view of the evaporation boat. [Figure 17] FIG. 17 is a cross-sectional view taken along the line BB in FIG. [Figure 18] FIG. 10 is a perspective view showing the configuration of a deposition boat according to a third embodiment of the present invention, as viewed from the bottom side. [Figure 19] FIG. 2 is a side view of the evaporation boat. [Figure 20] 10 is an experimental result showing an example of temperature distribution in the longitudinal direction of a deposition boat during electrical heating of aluminum. [Figure 21] 21 is an enlarged view showing the temperature distribution in the vicinity of one end side of the cavity portion in FIG. 20. FIG. [Figure 22] 10 shows experimental results illustrating an example of the relationship between the length (Lt) of the electrode placement section along the boat longitudinal direction, and the power and current density. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] 1 is a schematic diagram of a vacuum deposition apparatus 100 according to one embodiment of the present invention. In this embodiment, a winding-type vacuum deposition apparatus will be described as an example.

[0017] [Basic configuration of vacuum deposition equipment] The vacuum deposition apparatus 100 of this embodiment includes a vacuum chamber 10, a deposition source 20, a film transport unit 30, and a control unit 50.

[0018] (vacuum chamber) The vacuum chamber 10 is a sealed metal container connected to a ground potential. The vacuum chamber 10 is connected to an exhaust line 13 having a vacuum pump 11 and a vacuum valve 12. The interior of the vacuum chamber 10 is configured so that it can be evacuated to or maintained at a predetermined reduced pressure atmosphere by the exhaust line 13.

[0019] The vacuum chamber 10 accommodates an evaporation source 20 and a film transport unit 30. A partition plate 14 is provided inside the vacuum chamber 10, and this partition plate 14 divides the inside of the vacuum chamber 10 into a film formation chamber 15 and a transport chamber 16.

[0020] (evaporation source) The evaporation source 20 is a film-forming unit that heats and evaporates an evaporation material. Fig. 2 is a schematic perspective view showing the configuration of the evaporation source 20, and Fig. 3 is a schematic side cross-sectional view thereof. The evaporation source 20 has an evaporation boat 21 and a material supply unit 22.

[0021] The deposition boat 21 has a boat body 210 made of a plate-shaped high-melting-point material (resistance heater) that can generate heat to a temperature higher than the melting point of the deposition material M when current is applied. Examples of the high-melting-point material include ceramic materials such as boron nitride, and metal materials such as molybdenum, tungsten, and tantalum. In this embodiment, the boat body 210 is made of a mixture of boron nitride (BN) and titanium boride (TiB2).

[0022] A plurality of deposition boats 21 are arranged in the width direction of the film F, with their longitudinal direction facing the transport direction of the film F, for example. The deposition boat 21 has a cavity portion (storage portion) 211 for accommodating a deposition material M and its molten metal Mm on an upper surface S1, which is one surface of a boat body 210 facing the main roller 33. The cavity portion 211 is a rectangular recess having a depth D formed on the upper surface S1 of the deposition boat 21. The depth D is the distance from the upper surface S1 to the deepest part (lowest part) of the cavity portion 211.

[0023] A pair of electrode mounting portions 212a, 212b are provided at both longitudinal ends of the boat main body 210, to which electrodes connected to the power supply circuit 23 are respectively attached. The electrode mounting portions 212a, 212b are fixing pieces to which the electrodes are fixed, and the electrodes are attached to the electrode mounting portions 212a, 212b using fixing jigs (not shown), thereby forming terminal portions 23a, 23b at connection positions between the boat main body 210 and the electrodes.

[0024] The deposition boat 21 melts the deposition material accommodated in the cavity 211 by heating with an electric current supplied from a power supply circuit 23. The power supply circuit 23 is disposed outside the vacuum chamber 10, and the power supplied to the deposition boat 21 is controlled by a control unit 50, which will be described later.

[0025] The material supply unit 22 is disposed in the film formation chamber 15 and supplies the deposition material M to the container of the deposition boat 21. The deposition material M is formed into a wire-like member having a wire diameter of, for example, about 2 mm. The deposition material is, but is not limited to, aluminum. Examples of the deposition material include metal materials such as copper, lithium, tin, and zinc, alloys of these metals, and oxides, nitrides, and fluorides of these metals.

[0026] The material supply unit 22 includes a feed roller 221 that feeds out the wire-shaped vapor deposition material M in the longitudinal direction. The feed roller 221 is configured to be able to feed the vapor deposition material M continuously at a predetermined speed or intermittently at a predetermined cycle. The material supply unit 22 is further configured to be able to move horizontally as shown by arrow A in FIG. 3 so as to change the supply position of the vapor deposition material M with respect to the cavity portion 211 of the vapor deposition boat 21. The supply of the vapor deposition material M by the feed roller 221 and the horizontal movement of the material supply unit 22 are controlled by a control unit 50, which will be described later.

[0027] (film transport section) The film transport section 30 is disposed in the transport chamber 16. The film transport section 30 has an unwinding roller 31 that continuously pays out the film F, which is the base material, a take-up roller 32 that continuously takes up the film F unwound from the unwinding roller 31, and a main roller 33 (transport roller) that is installed in the film transport path between the unwinding roller 31 and the take-up roller 32. The film transport section 30 further has a first auxiliary roller 34 that is disposed upstream of the main roller 33, and a second auxiliary roller 35 that is disposed downstream of the main roller 33.

[0028] Unwinding roller 31, winding roller 32, and main roller 33 each include a rotational drive unit (not shown) and are configured to rotate at a predetermined speed in the direction of the arrow shown in Fig. 1. This causes film F to be transported at a predetermined transport speed from unwinding roller 31 to winding roller 32 within vacuum chamber 10. Note that first auxiliary roller 34 and second auxiliary roller 35 are each configured as free rollers without rotational drive units, but the present invention is not limited to this and each may also include a rotational drive unit.

[0029] At least a portion of the main roller 33 faces the vapor deposition source 20 through an opening 14a provided in the partition plate 14. The film F is transported toward the take-up roller 32 while being wrapped around the outer circumferential surface of the main roller 33 at a predetermined wrap angle, and a film is formed on the surface area exposed to the film formation chamber 15 through the opening 14a by the vapor deposition source 20. The film F is taken up by the take-up roller 32 while a film is continuously formed on the outer circumferential surface of the main roller 33 in the longitudinal direction.

[0030] The film F is an insulator and is made of a resin film such as an OPP (oriented polypropylene) film, a PET (polyethylene terephthalate) film, a PPS (polyphenylene sulfite) film, a PI (polyimide) film, etc. However, the film F is not limited to these, and may be made of a metal film such as a copper film or an aluminum film.

[0031] Since the exhaust line 13 is connected to the film formation chamber 15, a pressure difference occurs between the film formation chamber 15 and the transfer chamber 16 during exhaust due to the presence of the partition wall 14. This pressure difference prevents the vapor flow of the deposition material from entering the transfer chamber 16 through the opening 14a.

[0032] Although not shown, a shutter capable of blocking the vapor flow of the deposition material M from reaching the film F supported on the main roller 33 from the deposition source 20 (deposition boat 21) may be disposed between the deposition source 20 (deposition boat 21) and the main roller 33. For example, by closing the shutter until the evaporation of the deposition material M in the deposition source 20 stabilizes, such as at the beginning of film formation, the deposition material can be deposited on the film F at a stable film formation rate.

[0033] (Control unit) The control unit 50 is a controller that controls the overall operation of the vacuum deposition apparatus 100, including the exhaust line 13, the deposition source 20, and the film transport unit 30. The control unit 50 is realized by hardware elements used in a computer, such as a CPU (Central Processing Unit), RAM (Random Access Memory), and ROM (Read Only Memory), as well as necessary software.

[0034] The control unit 50 is configured to control at least one of the supply speed or supply position of the deposition material M in the deposition boat 21 to the cavity 211 and the electric power applied to the deposition boat 21.

[0035] [Study on splash generation] In this type of vacuum deposition apparatus, it is necessary to maintain a stable deposition rate and prevent a decrease in product yield due to splashing. However, the frequency of splashing varies greatly depending on the melting rate of the deposition material in the deposition source and the amount of molten metal.

[0036] 4 and 5, if the depth d of the molten metal Mm in the accommodation portion 21a of the deposition boat 21 becomes large, gas (bubbles) G generated in the molten metal Mm during heating of the deposition material M grows larger before reaching the liquid surface of the molten metal Mm, which tends to increase the diameter of the droplets (splashes) Ms that fly from the liquid surface of the molten metal Mm toward the film F directly above. As a result, the shape of the splashes Ms that adhere to the deposition surface of the film F becomes larger, which may cause deterioration in the appearance and flatness of the deposition surface. For this reason, it is necessary to adjust the amount of the molten metal Mm so that the depth of the molten metal does not become too large.

[0037] In FIG. 2, the inventors have determined that the width W is 45 mm, the length L is 150 mm, and the volume of the cavity portion 211 is 3900 mm 3 Aluminum was vapor-deposited onto a film F using a vapor deposition boat sample (hereinafter also referred to as vapor deposition boat 21S), and the number of splashes exceeding 80 μm in size per unit area was measured. The shortest distance between the vapor deposition boat 21S and the film F was 270 mm, and the heating temperature of the vapor deposition boat 21S was 1500°C (power: 28 W). As a result of the experiment, when the depth d of the molten metal was 0.4 mm, the number was 62.5 [splashes / m2], whereas when the depth d was 0.2 mm, the number was 1.9 [splashes / m2]. These results confirmed that, when the number of splashes is set to 10 [splashes / m2], the depth d of the molten metal is preferably less than 0.4 mm, and more preferably 0.3 mm or less.

[0038] 6, splashing can also occur when the spread (area) of the molten metal Mm in the cavity portion 211 of the deposition boat 21 is small. For example, as shown schematically in FIGS. 7A and 7B, when the spread of the molten metal Mm is small, a large temperature difference is likely to occur in the deposition boat 21 between the region in contact with the molten metal Mm and the region not in contact with it. If a large fluctuation in the amount of the molten metal Mm occurs and the area of ​​the molten metal Mm expands in this state, the molten metal Mm on the low-temperature side is rapidly heated upon contact with the deposition boat 21 on the high-temperature side, which makes splashing Ms more likely to occur. Therefore, it is necessary to adjust the width of the deposition boat 21 perpendicular to the longitudinal direction (hereinafter also referred to as the boat width) and the width of the cavity portion 211 along the width direction to prevent a large temperature difference in the deposition boat 21 between the region in contact with the molten metal Mm and the region not in contact with it.

[0039] [Details of the evaporation boat] The deposition boat 21 of this embodiment will be described in detail below.

[0040] First Embodiment Fig. 8 is a perspective view showing the entire deposition boat 21A of this embodiment, Fig. 9 is a plan view thereof, and Fig. 10 is a cross-sectional view taken along line AA in Fig. 9. In each figure, parts corresponding to those in Fig. 2 are denoted by the same reference numerals, and their explanation will be omitted or simplified. In each figure, the X-axis, Y-axis, and Z-axis directions indicate three axes that are orthogonal to each other.

[0041] The evaporation boat 21A of this embodiment includes a boat body 210 having a longitudinal direction in the X-axis direction and a width direction in the Y-axis direction, a cavity portion 211 formed on an upper surface S that is one surface of the boat body 210, and a pair of electrode attachment portions 212a and 212b provided on both longitudinal end portions of the boat body 210. The length of the boat body 210 is, for example, 150 mm, and the thickness is, for example, 9 mm.

[0042] In the deposition boat 21A of this embodiment, the cross-sectional shape when viewed from the longitudinal direction (X-axis direction) of the boat body 210 is formed to be an inverted trapezoid so that one surface (upper surface) S1 of the boat body 210, on which the cavity portion 211 is formed, is wider than the other surface (lower surface) S2 (see Figure 10).

[0043] (About boat width) During aluminum deposition, the surface of the molten aluminum changes periodically depending on the feed rate of the aluminum wire. As a result, the end of the cavity 211 containing the molten aluminum comes into contact with the surface of the boat body 210 near that end and is rapidly heated, which can easily cause splashing due to the mechanism shown in Fig. 7. For this reason, it is desirable to keep the temperature difference between the cavity 211 and its surrounding area as low as possible.

[0044] 11 shows the simulation results of the temperature distribution in the boat body 210 when the evaporation boat 21A is electrically heated. -8 The pressure was Ω·m, the cavity width was 35 mm, the cavity depth was 1 mm, the deposition material was Al (aluminum), and the temperature of the molten metal was 1435°C ± 3°C. On the upper surface S1 of the boat body 210, the temperature of the cavity portion 211 in which the molten aluminum was accommodated was constant (isothermal), and in the region other than the cavity portion 211, the temperature was highest at both ends in the longitudinal direction of the cavity portion 211, and the temperature decreased the further away from the cavity portion 211.

[0045] 12 shows the relationship between the temperature difference between the end of the cavity portion 211 and a predetermined portion of the upper surface S1 of the boat body 210 in FIG. 11 and the boat width Wb (see FIG. 9). Here, the temperature difference was measured between one longitudinal end of the cavity portion 211 and the upper surface S1 of the boat body 210, which was 1 mm away from that end in the longitudinal direction. As shown in the figure, it was confirmed that the temperature difference tends to increase as the boat width Wb decreases. This is thought to be because as the boat width Wb decreases, the distance between both widthwise ends of the boat body and the cavity portion 211 decreases.

[0046] On the other hand, the results in Figure 12 show that a wider boat width Wb reduces the temperature difference between the contact area and the non-contact area of ​​the molten Al, thereby suppressing splashing due to periodic changes in the molten Al surface. However, if the boat width Wb is too wide, areas of the deposition boat other than the cavity portion 211 must be heated unnecessarily, resulting in reduced power efficiency. Furthermore, if the boat width Wb is too wide, the size of the deposition boat 21A increases, making it impossible to arrange the necessary number of deposition boats in the deposition area for the film F to achieve the desired deposition rate. Furthermore, even if the necessary number of deposition boats can be arranged, the distance between the deposition boats will be too close, making it more likely that the molten Al surface will fluctuate due to the Lorentz force from adjacent deposition boats.

[0047] Therefore, in this embodiment, the boat width Wb of the evaporation boat 21A is set to 60 mm or less, which can suppress a decrease in power efficiency and an increase in the size of the evaporation boat 21A, making it easier to arrange the required number of evaporation boats to achieve a target film formation rate and ensuring a distance between the evaporation boats that is sufficient to avoid the influence of the Lorentz force from adjacent evaporation boats.

[0048] (Regarding cavity width) As described above, the deposition boat of this embodiment is composed of a mixture of boron nitride (BN) and titanium boride (TiB2). In this case, the wettability between the deposition material (Al) and the deposition boat 21A is achieved by the reaction product AlN. Titanium boride (TiB2) dissolves in molten Al and tends to deposit as slag in low-temperature areas. Figure 13 is a schematic diagram showing an example of the distribution of molten metal Mm and slag Ms in the cavity.

[0049] The slag Ms tends to accumulate unevenly on both sides of the width of the cavity 211 (upper and lower sides in the figure). If the cavity width Wc is too narrow, as shown in Figure 13(A), the accumulation of slag Ms restricts the molten metal surface to a small area. When a certain volume of Al is restricted in the width direction, the depth of the molten metal Mm increases. As a result, as explained with reference to Figure 5, the gas (bubbles) G generated in the molten metal Mm grow large before reaching the liquid surface of the molten metal Mm, which tends to increase the diameter of the splashes Ms that fly from the liquid surface of the molten metal Mm toward the film F directly above.

[0050] On the other hand, if the cavity width Wc is too wide as shown in Fig. 13(B), the molten metal surface is subjected to the Lorentz force, and the molten metal does not spread in the width direction of the cavity 211, but tends to collect in the center of the cavity 211, resulting in an unstable state. As a result, the temperature difference between the region in contact with the molten metal Mm and the region not in contact with the molten metal Mm in the cavity 211 becomes large, and the molten metal Mm on the low-temperature side is rapidly heated by contact with the evaporation boat on the high-temperature side, as shown in Fig. 7(B), which makes splashes Ms more likely to occur.

[0051] Here, the Lorentz force acting on the molten metal Mm refers to the interaction between Lorentz force F1 generated by one current I1 and its electromagnetic field B1, and Lorentz force F2 generated by the other current I2 and its current magnetic field B2, when two currents I1 and I2 are flowing parallel to each other through the molten metal Mm in the cavity 211, as shown in Fig. 14. One Lorentz force F1 acts on the molten metal through which the other current I2 flows, and the other Lorentz force F2 acts on the molten metal through which the one current I1 flows, and these two Lorentz forces act in opposite directions. As a result, the molten metal Mm is unevenly distributed within the cavity 211 with a substantially constant width, resulting in a distribution of contact and non-contact areas with the molten metal Mm within the cavity 211. Furthermore, the magnitude of the Lorentz forces F1 and F2 varies over time depending on the amount and position of the molten metal Mm, which in turn causes the position of the molten metal Mm above the cavity to vary over time, which is thought to make splashes more likely to occur. Furthermore, the larger the current value, the larger the Lorentz force, so splashes are more likely to occur during high-speed deposition.

[0052] Table 1 shows the results of an experiment comparing the number of splashes and power efficiency when Al was evaporated onto film F with different boat widths Wb (mm) and cavity widths Wc (mm). The number of splashes was measured as the number of splashes per unit area that were larger than 80 μm in size.

[0053] [Table 1]

[0054] As shown in Table 1, even when the boat width Wb is 60 mm or less, if the cavity width Wc is too narrow, 21 mm or less, as in Sample 1, or too wide, 52 mm or more, as in Sample 4, the number of splashes was confirmed to be greater than in Samples 2 and 3. As a result, when the boat width Wb is 60 mm or less, it is preferable that the cavity width Wc be 22 mm or more and 51 mm or less, which can effectively suppress the occurrence of splashes. This makes it possible to suppress a decrease in product yield due to splashes even during high-speed film deposition.

[0055] <Second embodiment> Fig. 15 is a perspective view showing the configuration of an evaporation boat 21B according to a second embodiment of the present invention, Fig. 16 is a plan view thereof, and Fig. 17 is a cross-sectional view taken along line BB in Fig. 16. In Fig. 15, parts corresponding to those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0056] The deposition boat 21B of this embodiment differs from that of the first embodiment in the configuration of the cavity 211. That is, in this embodiment, the cavity 211 includes a pair of inclined surfaces 211a and 211b that are inclined upward from both sides in the width direction (Y-axis direction) of the cavity 211 toward the center in the width direction. The inclined surfaces 211a and 211b are formed with the same inclination angle, and form a top portion (ridge portion) 211c that is parallel to the longitudinal direction (X-axis direction) at the center in the width direction of the cavity 211.

[0057] The deposition boat 21B has a boat width Wb of 60 mm or less and a cavity width Wc of 22 mm to 51 mm, similar to those of the first embodiment, but is not limited thereto. In this embodiment, the deposition boat 21B of this embodiment is obtained by forming inclined surfaces 211a and 211b on the bottom surface of the cavity portion 211 of the deposition boat 21A shown in FIGS. 8 to 10 by cutting or other processes. The height Hc of the inclined surfaces 211a and 211b (height of the top portion 211c) is not particularly limited as long as the top portion 211c is covered with the molten metal of the deposition material, and is, for example, 1 mm to 10 mm. The top portion 211c may be located above the top surface S1. A portion of the lowest portion of the cavity portion 211 may have a surface substantially parallel to the top surface S1.

[0058] In the deposition boat 21B of this embodiment configured as described above, the cavity 211 has a pair of inclined surfaces 211a, 211b that slope upward toward the widthwise center of the deposition boat 21B. Therefore, even if the Lorentz force acts to move the molten metal toward the widthwise center of the cavity 211 when the deposition material is heated and melted by passing current through the deposition boat 21B, the weight of the molten metal reduces the Lorentz force. This suppresses uneven distribution of the molten metal within the cavity 211, thereby preventing a distribution of contact and non-contact regions with the molten metal within the cavity 211 and suppressing the occurrence of splashing. Furthermore, a decrease in product yield due to splashing can be suppressed even during high-speed film formation.

[0059] The present inventors conducted a similar experiment by forming the above-described pair of inclined surfaces in the cavity of an evaporation boat fabricated under the conditions of Sample 2 in Table 1, and confirmed that the number of splashes per unit area could be reduced from four to one.

[0060] <Third embodiment> Fig. 18 is a perspective view showing the configuration of an evaporation boat 21C according to a third embodiment of the present invention, as seen from the bottom side, and Fig. 19 is a side view thereof. In these figures, parts corresponding to those in the first embodiment described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0061] The evaporation boat 21C of this embodiment includes a boat body 210, a cavity 211, and electrode attachment portions 212a and 212b, similarly to the first embodiment. The evaporation boat 21C has a boat width Wb of 60 mm or less and a cavity width Wc of 22 mm or more and 51 mm or less, similarly to the first embodiment, but is not limited thereto.

[0062] In this embodiment, the upper surface S1 side including the cavity portion 211 of the evaporation boat 21C has the same configuration as in the first or second embodiment, but the configuration of the lower surface S2 side is different from that in the first embodiment. That is, in this embodiment, the electrode attachment portions 212a and 212b have electrode arrangement portions 213a and 213b formed by cutting out the lower surface S2, which is the other surface of the boat body 210, from both longitudinal end portions of the boat body 210 toward the longitudinal center of the boat body 210.

[0063] The electrode placement portions 213a, 213b correspond to cutouts that thin the electrode mounting portions 212a, 212b, and electrodes Ea, Eb, which are connected to the power supply circuit 23 (FIG. 3), are placed in the areas where the cutouts are formed. The electrodes Ea, Eb are typically electrode terminals equipped with a water-cooling mechanism. The electrodes Ea, Eb form terminal portions 23a, 23b by contacting both longitudinal ends of the boat body 210 cut out by the cutouts. Note that the electrodes Ea, Eb are spaced apart from and out of contact with the bottom surfaces of the electrode mounting portions 212a, 212b, and only the tips of the electrodes Ea, Eb contact the boat body 210, thereby preventing a decrease in temperature of the boat body 210 due to contact between the water-cooled electrodes Ea, Eb and the electrode mounting portions 212a, 212b. By providing the electrode arrangement portions 213a, 213b in this manner, both longitudinal ends of the cavity portion 211 can be brought closer to the terminal portions 23a, 23b, thereby reducing the temperature difference between the above-mentioned both ends of the cavity portion 211 and the area of ​​the boat body 210 outside them.

[0064] The electrode arrangement portions 213a, 213b have overlapping regions OL between the electrode arrangement portions 213a, 213b and both ends of the cavity portion 211 in the longitudinal direction (X-axis direction) when viewed from the thickness direction of the boat body 210, and the size of these overlapping regions OL is 10 mm or less.

[0065] Fig. 20 shows experimental results illustrating an example of temperature distribution in the longitudinal direction of an evaporation boat during electrical heating of aluminum, comparing an evaporation boat without electrode arrangement portions 213a and 213b (original boat, hereinafter also referred to as a comparative example) with an evaporation boat 21C (cut boat) of this embodiment that has electrode arrangement portions 213a and 213b. Fig. 21 is an enlarged view showing the temperature distribution near one end of the cavity portion 211 in Fig. 20. The boat width was 38 mm, the OL was 5 mm, and the length Lt (see Fig. 19) of the electrode arrangement portions 213a and 213b along the boat longitudinal direction was 15 mm.

[0066] 20 and 21, in the comparative example, there are regions near both ends of the cavity that are hotter than the cavity itself. However, in this embodiment, there are no regions corresponding to these high-temperature regions, and the cavity forms the highest-temperature region. In other words, according to this embodiment, there is no region outside the cavity that is hotter than the cavity, so splashing caused by fluctuations in the molten metal surface can be more effectively suppressed. Furthermore, a decrease in product yield due to splashing can be suppressed even during high-speed film formation.

[0067] Furthermore, the inventors conducted a similar experiment by forming the above-mentioned electrode placement section on a deposition boat prepared under the conditions of Sample 2 in Table 1, and confirmed that the number of splashes per unit area could be reduced from four to two.

[0068] The magnitude of Lt determines the relative position between the cavity 211 and the terminal portions 23a and 23b. Therefore, the magnitude of Lt is correlated with the electric power used to electrically heat the deposition boat 21C to a predetermined temperature and the current density flowing through Al in the cavity 211. For example, Fig. 22 shows experimental results illustrating an example of the relationship between the magnitude of Lt, the electric power, and the current density.

[0069] As shown in FIG. 22, the current density tends to increase as Lt increases because the resistance between the terminal portions 23a, 23b and the molten aluminum decreases. Meanwhile, power consumption tends to decrease when Lt is between 0 and 10 mm, but begins to increase once Lt exceeds 10 mm. This is thought to be because, when Lt exceeds 10 mm, the cooling effect of the electrode placement portions 213a, 213b inhibits heating of the evaporation boat, increasing the power required for heating. Therefore, to prevent a decrease in power efficiency, the size of Lt is preferably 20 mm or less, more preferably 15 mm or less. Furthermore, the overlapping region between the longitudinal ends of the cavity portion and the electrode placement portion when viewed from the thickness direction of the boat body (corresponding to OL in FIG. 19) is preferably 10 mm or less, more preferably 5 mm or less. Alternatively, the overlapping region OL may be eliminated.

[0070] Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and that various modifications can be made.

[0071] For example, in the above embodiment, a roll-to-roll vacuum deposition apparatus has been described as an example, but the present invention can also be applied to a sheet-to-sheet vacuum deposition apparatus. [Explanation of symbols]

[0072] 10...Vacuum chamber 20...evaporation source 21, 21A, 21B, 21C... Evaporation boat 23a, 23b…terminal section 50...Control unit 100...Vacuum deposition device 210...Evaporation boat 211... Storage unit 211a, 211b...slanted part 212a, 212b...electrode mounting portion 213a, 213b...electrode arrangement part M: Evaporation material Mm...molten metal

Claims

1. a boat body formed of a plate-shaped resistance heater elongated in one axial direction; electrode attachment portions provided at both longitudinal ends of the boat body; a cavity portion formed on one surface of the boat body, the cavity portion having a rectangular shape in plan view and elongated in the uniaxial direction, capable of accommodating a vapor deposition material; Equipped with a width direction of the boat body perpendicular to the axial direction being 60 mm or less; The length of the cavity in the width direction perpendicular to the axial direction is 22 mm or more and 51 mm or less. Evaporation boat.

2. The evaporation boat according to claim 1 , The depth of the cavity is 1 mm or less. Evaporation boat.

3. The evaporation boat according to claim 1 , The cavity portion includes a pair of inclined surfaces that are inclined upward from both side portions in the width direction toward a center portion in the width direction. Evaporation boat.

4. The evaporation boat according to claim 3, The height of the pair of inclined surfaces is 1 mm or more and 10 mm or less. Evaporation boat.

5. The evaporation boat according to claim 1 , The electrode mounting portion has an electrode placement portion formed by cutting out the other surface of the boat body from the both end portions toward the center in the longitudinal direction of the boat body. Evaporation boat.

6. The evaporation boat according to claim 5, When viewed from the thickness direction of the boat body, the overlapping area between both ends of the cavity in the longitudinal direction and the electrode placement portion is 10 mm or less. Evaporation boat.

7. A vacuum deposition apparatus comprising the deposition boat according to any one of claims 1 to 6.

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