Vacuum deposition device and vacuum deposition method

Abstract

Provided is a vacuum deposition device capable of effectively suppressing the occurrence of bumping of a vapor deposition material and reducing the amount of splash that adheres to a vapor-deposited substance to the extent possible.　The present invention comprises: a vapor deposition boat 3 including an accommodation section 31a disposed in a vacuum chamber 1; and a material supply unit Fu for supplying a wire-shaped vapor deposition material Em from above so as to abut against a bottom plate of the vapor deposition boat defining the accommodation section. The present invention comprises a measuring means 8 for measuring, when the vapor deposition material is melted and wet-spread in the accommodation section due to the vapor deposition material being supplied to the heated vapor deposition boat, the temperature of a molten metal Le of this wet-spread vapor deposition material at a plurality of locations. When the temperature difference between measured locations adjacent to each other exceeds a prescribed value, the material supply unit Fu is used to spread the molten surface of the vapor deposition material in the direction of the measurement location indicating the high temperature.

Description

Vacuum deposition apparatus and vacuum deposition method

[0001] The present invention relates to a vacuum deposition apparatus and method for depositing a vapor onto a deposition target in a vacuum chamber, and more particularly to an apparatus and method that can effectively prevent bumping of a deposition material.

[0002] One such vacuum deposition apparatus using an evaporation boat is known, for example, from Patent Document 1. The evaporation boat includes a boat body having a chamber for accommodating evaporation material and electrode mounting plates extending outward from the upper end of the boat body. The two electrode mounting plates are held (sandwiched) by a pair of upper and lower electrode plates, respectively, and is installed in a vacuum chamber. During evaporation on an object to be evaporated in a vacuum chamber, the boat body is heated by Joule heat by passing current between the two electrode mounting plates via the electrode plates from a power source. Then, a wire-shaped evaporation material made of metal, such as copper or aluminum, is supplied from above the bottom plate of the boat body that defines the accommodation portion so that it abuts against the bottom plate. The evaporation material melts and spreads within the accommodation portion, evaporating from the surface of the molten metal. The evaporated evaporation material adheres to the object to deposit a copper or aluminum film on the object.

[0003] It is known that during evaporation of the deposition material (deposition onto the deposition target) as described above, impurities from the deposition material precipitate on the outer periphery of the molten metal and accumulate without re-evaporating. Such impurities may also accumulate within the molten metal. As impurities accumulate, they block the wetting and spreading of the deposition material, narrowing the surface area of ​​the molten metal. It has been found that as the surface area of ​​the molten metal narrows, the amount of splashes adhering to the deposition target increases, resulting in a decrease in product yield. "Splash" refers to, for example, splashes that remain liquid from the surface of the molten metal and adhere to the deposition target without evaporating due to bumping. Therefore, the present inventors conducted extensive research and discovered the following.

[0004] When the temperature of the molten metal is measured at multiple locations during deposition on the substrate, initially, all measurement locations show the same temperature. However, as deposition progresses, relatively high temperatures appear, for example, at measurement locations located on the outer periphery of the molten metal. When the relatively high temperature locations are examined after deposition is completed, it is confirmed that a large amount of impurities have accumulated, or in other words, that the locations where impurities have accumulated tend to become relatively high temperatures. Furthermore, in the molten metal that has spread, depleted areas may appear, where the amount of molten metal locally decreases and the bottom plate of the boat body is exposed. These depleted areas also tend to become relatively high temperatures. Furthermore, it has been discovered that bumping is likely to occur when the deposition material comes into contact with the relatively high-temperature locations when it melts and spreads. Furthermore, as the surface area of ​​the molten metal becomes smaller, the frequency of bumping due to contact increases.

[0005] Japanese Patent Application Laid-Open No. 2007-46106

[0006] The present invention was made based on the above findings, and an object of the present invention is to provide a vacuum deposition apparatus and a vacuum deposition method that can effectively suppress the occurrence of bumping of the deposition material and reduce as much as possible the amount of splash that adheres to the deposition target.

[0007] In order to solve the above-mentioned problems, the vacuum evaporation apparatus of the present invention is for depositing evaporation material on an object to be evaporated in the vacuum chamber, and includes: an evaporation boat that is arranged in a vacuum chamber and has an evaporation material storage section; and a material supply unit that supplies wire-shaped evaporation material from above so as to abut against a bottom plate of the evaporation boat that defines the storage section. The vacuum evaporation apparatus is characterized in that it includes: a measuring means that, when the evaporation material melts and spreads in the storage section due to the evaporation material being supplied to the heated evaporation boat, measures the temperature of the molten evaporation material at a plurality of locations; and a molten surface expanding means that, when the temperature difference between adjacent measured locations exceeds a predetermined value, expands the molten evaporation material surface toward the measurement location that indicates the higher temperature.

[0008] In the present invention, the molten metal surface expanding means may be configured to move the tip of the deposition material that contacts the bottom plate of the deposition boat relative to the deposition boat, and alternatively or in addition, the supply speed of the wire-shaped deposition material may be changed.

[0009] In order to solve the above-mentioned problems, the vacuum deposition method of the present invention includes heating an deposition boat placed in a vacuum chamber, supplying a wire-shaped deposition material from above so that it abuts against a bottom plate that defines a storage section of the deposition boat, melting the deposition material in the storage section, and evaporating the wetted and spread deposition material to deposit it on an object to be deposited in the vacuum chamber. The vacuum deposition method includes the steps of: measuring the temperature of the molten deposition material at a plurality of locations when the deposition material melts and wets and spreads in the storage section due to the supply of the deposition material to the heated deposition boat; and, when a temperature difference between adjacent measured locations exceeds a predetermined value, spreading the molten deposition material toward the measurement location showing the higher temperature.

[0010] According to the above, when vapor deposition is performed on a target object in a vacuum chamber under a vacuum atmosphere, the boat body is energized to heat it with Joule heat, and a wire-shaped vapor deposition material is supplied from above so as to contact the bottom plate of the boat body that defines the container. When the vapor deposition material melts and spreads within the container, measurement of the molten metal temperature is initiated at multiple locations. If the temperature difference between adjacent measured locations exceeds a temperature experimentally determined in advance, it is determined that there is a risk of impurity accumulation or the appearance of a depletion location. For example, the tip of the vapor deposition material is moved relative to the vapor deposition boat toward the measurement location showing the higher temperature. At this time, splashing is prevented by preventing the tip of the vapor deposition material from directly contacting the measurement location showing the higher temperature (e.g., the location where impurities are accumulated). This causes the surface of the molten metal to expand toward that direction, minimizing impurity accumulation. Even if impurities are accumulated, the accumulated impurities are pushed toward the outer periphery of the container as the molten metal surface expands, minimizing a reduction in the molten metal surface area. As a result, the chances of the molten metal coming into contact with the relatively hot impurity accumulation areas are reduced, effectively suppressing the occurrence of bumping of the deposition material, and ultimately reducing the amount of splash that adheres to the deposition object as much as possible.

[0011] 1A and 1B are schematic cross-sectional views of a vacuum deposition apparatus according to an embodiment of the present invention, each illustrating a material supply unit, a plan view of a deposition boat illustrating a state when a deposition material is melted, and a plan view of a deposition boat illustrating a state when the surface of molten metal is expanded.

[0012] Hereinafter, with reference to the drawings, an embodiment of the vacuum deposition apparatus and vacuum deposition method of the present invention will be described using as an example a case in which a substrate Sw is a sheet-like substrate to be deposited, a deposition material Em is an aluminum wire-shaped deposition material, and the deposition material Em is supplied and evaporated to deposit an aluminum film on one surface of the substrate Sw in a vacuum chamber under a vacuum atmosphere. In the following, terms indicating directions such as up and down are, in principle, based on Figure 1, which shows the installation position of the apparatus.

[0013] 1, the vacuum deposition apparatus ES is a so-called winding type, and includes a vacuum chamber 1. A vacuum pump unit Pu, which is composed of a turbomolecular pump, a rotary pump, or the like, is connected to the vacuum chamber 1 via an exhaust pipe Ep, and a vacuum atmosphere (e.g., 10 －５ Pa) can be formed. The interior of the vacuum chamber 1 is divided into two chambers, an upper chamber and an lower chamber, by a partition plate 11. In FIG. 1, a transport unit 2 that transports the sheet-like substrate Sw at a constant speed is disposed in the transport chamber Ts located on the upper side. The transport unit 2 includes a payout roller 21 around which the sheet-like substrate Sw is pre-wound and which is driven to rotate by a motor 21a to pay out the sheet-like substrate Sw at a constant traveling speed, and a take-up roller 22 that is driven to rotate by a motor 22a to take up the sheet-like substrate Sw after the film formation. Inside an opening 12 formed in the partition plate 11, a can roller Cr is disposed facing a deposition boat 3 described below, around which a portion of the sheet-like substrate Sw is wound. The transport chamber Ts also includes a plurality of guide rollers Gr appropriately provided to guide the sheet-like substrate Sw paid out from the payout roller 21 to the can roller Cr and to guide the film-formed sheet-like substrate Sw from the can roller Cr to the take-up roller 22. On the other hand, in the vapor deposition chamber Vs located at the lower side in FIG. 1, a vapor deposition boat 3 is disposed as a vapor deposition source for vapor deposition on the portion of the substrate Sw wound around the can roller Cr.

[0014] The evaporation boat 3 includes a boat body 31 having a flat bottom and a recess 31a serving as a storage area for the evaporation material Em, and electrode mounting plates 32 extending horizontally outward from both longitudinal ends (left-right direction in FIG. 1 ) of the boat body 31. The evaporation boat 3 may be made of ceramic materials such as boron nitride, carbon, oxides and nitrides of aluminum or titanium, or metal materials such as molybdenum, tungsten, and tantalum. In the case of metal materials, metal plates with a higher melting point than the evaporation material Em can be integrally formed by press working. Two support bases 4, 4 made of an insulating material are installed on the inner surface 1a of the lower wall of the vacuum chamber 1, spaced apart in the longitudinal direction. A pair of upper and lower electrode plates 5a, 5b made of a highly conductive metal such as copper are detachably attached to the upper surfaces of the support bases 4, 4 by fastening means 41 such as bolts, while sandwiching the electrode mounting plates 32, 32 of the evaporation boat 3 from above and below.

[0015] When the electrode plates 5a, 5b holding the electrode mounting plates 32, 32 are attached, the evaporation boat 3 is installed at a predetermined height from the inner surface 1a of the lower wall of the vacuum chamber, with the bottom plate of the boat body 31, which defines the recess 31a, horizontal. A known constant-voltage control power supply Ps is connected to each of the electrode plates 5a, 5b. The boat body 31 can be heated by Joule heat by applying electricity between the electrode mounting plates 32, 32 from the constant-voltage control power supply Ps via the electrode plates 5a, 5b. An ammeter Am is provided in the electrical circuit between the constant-voltage control power supply Ps and the electrode mounting plates 32, 32 to measure the current value when electricity is applied at a constant voltage. A storage chamber Ss is defined within the evaporation chamber Vs by another partition plate 13. The storage chamber Ss houses a material supply unit Fu for continuously or intermittently supplying a wire-shaped evaporation material Em to the recess 31a of the boat body 31.

[0016] 2(a) and 2(b), the material supply unit Fu includes a feed roller Fr around which a wire-shaped vapor deposition material Em is wound in advance, and a feed mechanism 6 that feeds a leading end Em1 of the vapor deposition material Em drawn from the feed roller Fr into the recess 31a. The vapor deposition material Em is, for example, formed to an outer diameter of 1 mm to 5 mm. The feed mechanism 6 includes a pair of support bases 61 erected on the inner surface 1a of the lower wall of the vacuum chamber 1, and a gear box 62 attached to the upper part of the support bases 61. The gear box 62 includes a worm wheel 64 that is driven to rotate by a rotation shaft 63a of a first drive motor 63, and a worm gear 65 that meshes with the worm wheel 64. The shaft 65a of the worm gear 65 is journaled to the gear box 62, so that when the rotation shaft 63a of the first drive motor 63 is driven to rotate, the gear box 62 rotates within a predetermined angular range in the vertical direction. A support 66 is provided on the upper cover 62a of the gear box 62, and a pair of a drive roller 66a and a pressure roller 66b are arranged at a predetermined position on the support 66 to sandwich the wire-shaped deposition material Em.

[0017] A rotary shaft 67a of a second drive motor 67 provided in the gearbox 62 is connected to the support 66, allowing the support 66 to rotate around the rotary shaft 67a. A guide tube 68, through which the deposition material Em passes, is also attached to the support 66. The guide tube 68 is sized so that its tip protrudes from a through-hole 13a formed at a predetermined position in the partition plate 13. The vacuum deposition system ES includes a control unit Uc. The control unit Uc is a well-known device including a microcomputer, a sequencer, a memory, etc., and controls the overall operation of operating parts such as the vacuum pump Pu, the motors 21a and 22a, the first and second drive motors 63 and 67 of the material supply unit Fu, and the constant-voltage control power supply Ps. Furthermore, as will be described later, the control unit Uc receives input of the temperature measured by the measuring means 8, and controls the first and second motors 63, 67 of the material supply unit Fu based on this input, thereby moving the tip end Em1 of the evaporation material Em abutting against the bottom plate of the boat body 31 relative to the boat body 31. A vacuum evaporation method using the vacuum evaporation apparatus ES will be described below.

[0018] When an aluminum film is deposited on a sheet-shaped substrate Sw in a vacuum chamber 1 using a vacuum deposition apparatus ES (i.e., the vacuum deposition method of this embodiment), the boat body 31 is heated by Joule heat by applying current between the electrode mounting plates 32, 32 via the electrode plates 5a, 5b from a constant-voltage control power supply Ps. After a predetermined time has elapsed, the wire-shaped deposition material Em is unwound at a predetermined speed by the feed mechanism 6 of the material supply unit Fu. The tip Em1 of the deposition material Em, which contacts the bottom plate of the boat body 31 defining the storage section 31a, gradually melts and spreads, and the molten deposition material Em on the surface of the wetted melt evaporates. Simultaneously, the motors 21a, 22a of the transport unit 2 are driven to rotate, unwinding the sheet-shaped substrate Sw at a constant travel speed. As a result, the evaporated deposition material Em adheres to the portion of the sheet-shaped substrate Sw wrapped around the can roller Cr, depositing an aluminum film. The deposition rate at this time is set to, for example, a range of 200 mm / min to 2000 mm / min.

[0019] During deposition on the sheet-like substrate Sw, as shown in FIG. 3, impurities precipitate on the outer periphery of the molten metal Le and accumulate without re-evaporating (the deposits are indicated by Se in FIG. 3). Such impurities may also accumulate in the molten metal. When the deposits Se block the spreading of the deposition material Em, the surface area of ​​the molten metal Le is narrowed, increasing the amount of splashes that adhere to the sheet-like substrate Sw and reducing product yield. This is thought to be due to the fact that the area where the deposits Se are present becomes relatively hot, and when the spreading deposition material Em comes into contact with it, bumping occurs more easily. Furthermore, as the surface area of ​​the molten metal narrows, the number of bumping events due to contact increases. Furthermore, when a depletion point (not shown) appears in the spreading molten metal, where the amount of molten metal is locally reduced and the bottom plate of the boat body 31 is exposed, the temperature also tends to become relatively high.

[0020] In this embodiment, a viewing window 7 is provided on the wall of the vacuum chamber 1, and a measuring device 8 is provided to measure the temperature of the molten aluminum Le of the deposition material Em at multiple locations through the viewing window 7 (see FIG. 1 ). The measuring device 8 is not particularly limited as long as it can measure the temperature of the molten aluminum Le; for example, a known radiation thermometer or near-infrared camera can be used. Specifically, the measuring device 8 measures the temperature of the molten aluminum Le at eight measurement positions MP1 to MP8 spaced apart along the longitudinal direction of the boat body 31, taking into account the wet spread of the deposition material Em. While this embodiment describes an example in which the measurement positions MP1 to MP8 are set in a row along the longitudinal direction to measure the temperature, this is not limiting, and the positions and number of the measurement positions MP1 to MP8 can be set as desired. During deposition on the sheet-like substrate Sw, the temperatures at the measurement positions MP1 to MP8 are measured, and the temperatures at each measurement position MP1 to MP8 are input to the control unit Uc. In this case, the temperature difference between the temperature of the molten metal Le and the temperature at which impurities can accumulate is experimentally determined in advance and stored in the control unit Uc.

[0021] During temperature measurement at each measurement position MP1 to MP8, if the temperature difference between adjacent measurement points, for example, measurement positions MP6 and MP7, exceeds a temperature experimentally determined in advance, it is determined that this is a state in which impurities may accumulate or a depleted area may appear, and the tip Em1 of the evaporation material Em, for example, is moved relative to the boat body 31 toward the measurement position MP7, which indicates a higher temperature. Specifically, the delivery mechanism 6 of the material supply unit Fu serves as the molten metal surface expanding means of this embodiment, and the worm gear 65 is rotated via the worm wheel 64 of the delivery mechanism 6, and the gear box 62 is rotated within a predetermined angular range relative to the vertical direction, thereby moving the tip end Em1 of the evaporation material Em back and forth in the longitudinal direction of the boat body 31 (to the right in FIG. 3 in this embodiment), and / or the support 66 is rotated around the rotation shaft 67a by the second drive motor 67, thereby moving the tip end Em1 of the evaporation material Em back and forth in the width direction perpendicular to the longitudinal direction of the boat body 31 (to the downside in FIG. 3 in this embodiment). At this time, splashing is prevented by preventing the tip end Em1 of the evaporation material Em from coming into direct contact with a measurement point showing a high temperature. For example, in cases where impurities accumulate in the molten metal Le, the drive roller 66a of the material supply unit Fu may be used as a molten metal surface expanding means, and the molten metal surface may be expanded toward the measurement position MP7, which indicates a higher temperature, by controlling the drive roller 66a to change the supply speed of the wire-shaped deposition material Em to the boat body 31. In other words, the molten metal surface may be expanded by increasing the supply speed of the wire-shaped deposition material Em.

[0022] As shown in FIG. 4 , the relative movement of the tip Em1 of the vapor deposition material Em relative to the boat body 31 causes the surface of the molten metal Le to expand toward the measurement position MP7, which indicates a higher temperature. This minimizes the accumulation of impurities. Even if impurity deposits Se are present, the deposits Se are pushed toward the outer periphery of the recess 31a of the boat body 31 as the molten metal surface expands, thereby minimizing the reduction in the molten metal surface area. Similarly, the occurrence of depleted areas of the molten metal can be monitored. As a result, the opportunity for the molten metal Le to come into contact with the depleted areas and deposits Se, which are relatively hot, is reduced, effectively suppressing the occurrence of bumping of the vapor deposition material Em. Consequently, the amount of splashing adhering to the sheet-like substrate Sw can be minimized. Experiments conducted by the inventors have confirmed that the amount of splashing adhering to the sheet-like substrate Sw can be reduced to one-fifth by appropriately adjusting the measurement position and temperature difference.

[0023] Although the above describes an embodiment of the present invention, various modifications are possible without departing from the scope of the technical concept of the present invention. In the above embodiment, a material supply unit Fu is used as a melt level expanding means, and its delivery mechanism 6 moves the tip Em1 of the vapor deposition material Em relative to the boat body 31 or changes the delivery speed of the vapor deposition material Em. However, this is not limited to this, and a wide variety of known methods can be applied. Furthermore, in the above embodiment, the vapor deposition material Em is made of aluminum, but this is not limited to this. The vacuum vapor deposition method of the present invention can be widely applied as long as impurities precipitate around the spreading vapor deposition material Em during vapor deposition and these precipitates accumulate without re-evaporating. For example, the vapor deposition material Em can be made of copper. Furthermore, while the above description uses a sheet-shaped substrate Sw on which an aluminum film is formed, the vapor deposition target is not limited to this, and the present invention can be widely applied to forming a film on a substrate with a predetermined contour, such as glass or a silicon wafer.

[0024] ES...vacuum deposition apparatus, Em...wire-shaped deposition material, Em1...tip of deposition material, Uc...control unit, Sw...sheet-shaped substrate (subject to deposition), 1...vacuum chamber, 3...deposition boat, 31...boat body, 31a...recess (container for deposition material), Fu...material supply unit (means for expanding molten metal surface), 8...means for measuring molten metal temperature, MP1 to MP8...measurement position (measurement point), Le...molten deposition material, Se...deposit.

Claims

1. A vacuum evaporation apparatus for depositing vapor onto an object within the vacuum chamber, comprising: an evaporation boat arranged within a vacuum chamber and having an accommodation section for evaporation material; and a material supply unit that supplies wire-shaped evaporation material from above so as to abut against the bottom plate of the evaporation boat that defines the accommodation section; the apparatus further comprising: measuring means for measuring the temperature of the molten evaporation material at multiple locations when the evaporation material melts and spreads within the accommodation section as a result of being supplied to the heated evaporation boat; and molten surface expanding means for expanding the molten evaporation material surface toward the measurement location showing the higher temperature when the temperature difference between adjacent measurement locations exceeds a predetermined value.

2. A vacuum deposition apparatus according to claim 1, characterized in that the melt surface expanding means is configured to move the tip of the deposition material that abuts against the bottom plate of the deposition boat relative to the deposition boat.

3. A vacuum deposition apparatus according to claim 1 or claim 2, characterized in that the melt surface expanding means is configured to change the supply speed of the wire-shaped deposition material.

4. A vacuum deposition method for heating an evaporation boat placed in a vacuum chamber, supplying a wire-shaped evaporation material from above so that it abuts against a bottom plate that defines the accommodation section of the evaporation boat, melting the evaporation material in the accommodation section, and evaporating the wet, spread material to deposit it on an object to be evaporated in the vacuum chamber, the method comprising the steps of: measuring the temperature of the molten evaporation material at multiple locations when the evaporation material melts and wets and spreads in the accommodation section as a result of being supplied to the heated evaporation boat; and, when the temperature difference between adjacent measured locations exceeds a predetermined value, spreading the molten evaporation material toward the measurement location showing the higher temperature.

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