Vacuum deposition system and vacuum deposition method

Abstract

Provided is a vacuum deposition system that, without additional equipment, is capable of effectively suppressing adhesion of a splash onto a deposition object.　A vacuum deposition system ES comprises: a vapor deposition boat 3 that includes a boat body 31 having a storage part 31a of a vapor deposition material Em; a material supply unit 6 for supplying the wire-shaped vapor deposition material from above so as to abut a bottom plate of the boat body; a power source Ps for heating the boat body by supplying power; and a control unit Uc. The vacuum deposition system ES further comprises an ammeter Am for detecting current at the time of energization by the power source, the current changing together with the amount of molten metal when the vapor deposition material melts and is wet-spread in the storage part. The control unit obtains the average value of the current values detected by the ammeter Am per unit time, and changes the current value by controlling the power source on the basis of each of the average values successively obtained.

Description

Vacuum deposition system and vacuum deposition method

[0001] The present invention relates to a vacuum deposition system and a vacuum deposition method, and more particularly to a system that can minimize the amount of splash that adheres to an object to be deposited.

[0002] One such vacuum deposition system using an evaporation boat is known, for example, from Patent Document 1. The evaporation boat includes a boat body having a deposition material storage area 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 and installed in a vacuum chamber. During deposition on a target object in a vacuum chamber, a power source applies current between the two electrode mounting plates via the electrode plates, thereby heating the boat body with Joule heat. Then, a wire-shaped deposition material made of metal, such as copper or aluminum, is supplied from above the bottom plate of the boat body that defines the storage area so that it abuts against the bottom plate. The deposition material melts and spreads within the storage area, evaporating from the molten metal surface. The evaporated deposition material adheres to the target object, depositing a copper or aluminum film on the target object.

[0003] It is known that the amount of molten metal fluctuates during evaporation of the deposition material (during deposition on the deposition target) as described above. Such fluctuations in the amount of molten metal increase the amount of splash adhering to the deposition target, which can reduce product yield. "Splash" refers to, for example, material that remains liquid and splashes from the surface of the molten metal and adheres to the deposition target without evaporating due to bumping. Conventionally, users of vacuum deposition equipment periodically visually check the amount of molten metal and adjust the electrical characteristics (power, voltage, current, resistance, etc.) or the supply rate of wire-shaped deposition material to the storage unit based on their own experience. In such cases, it has been proposed to install an imaging device, such as a camera, to capture images of the deposition boat during deposition and analyze the captured images to control the electrical characteristics and supply rate (see, for example, Patent Document 2). However, this approach increases the number of components, resulting in higher costs.

[0004] JP 2007-46106 A JP 2022-507610 A

[0005] In view of the above, an object of the present invention is to provide a vacuum deposition system and a vacuum deposition method that can effectively suppress the adhesion of splashes to a deposition target without the need for additional equipment.

[0006] To achieve the above object, the vacuum deposition system of the present invention for evaporating a deposition material in a vacuum chamber under a vacuum atmosphere and depositing the material on a deposition target comprises: a deposition boat having a boat body with a deposition material storage compartment and electrode mounting plates extending from both ends of the boat body; a material supply unit that supplies wire-shaped deposition material from above so as to abut against a bottom plate of the boat body that defines the storage compartment; a power source that passes current between the electrode mounting plates to heat the boat body; and a control unit, the system further comprising a detection means for detecting an electrical characteristic, which changes with the amount of molten metal when the deposition material melts and spreads in the storage compartment, when energized by the power source, as a state quantity; the state quantity being a state quantity; the control unit calculates an average value of the state quantity detected by the detection means per unit time and controls the power source to change the electrical characteristic based on the successively calculated average values. In this case, the control unit may control the material supply unit to change the deposition material supply rate based on the successively calculated average values ​​in addition to or instead of the change in the electrical characteristic.

[0007] In order to solve the above-mentioned problems, the vacuum deposition method of the present invention for evaporating a deposition material in a vacuum chamber in a vacuum atmosphere and depositing the material on an object to be deposited includes the steps of: using a deposition boat having a boat body having a storage section for the deposition material as a deposition source and electrode mounting plate sections extending from both ends of the boat body; heating the boat body by passing electricity between the electrode mounting plate sections; and supplying a wire-like deposition material from above so that the wire-like deposition material abuts against a bottom plate of the boat body that defines the storage section; detecting, as a state quantity, an electrical characteristic when electricity is passed from a power source, which changes with the amount of molten metal when the deposition material melts and spreads in the storage section; calculating an average value of the state quantities detected by the detection means per unit time; and changing the electrical characteristic using the power source based on the respective average values ​​obtained successively.

[0008] Here, when depositing a metallic (conductive) evaporation material such as copper or aluminum onto a substrate, a constant-voltage controlled power supply is used as a power source. The evaporation boat is heated by applying current to the boat body, and the evaporation material is supplied at a predetermined supply rate from above the bottom plate of the boat body, which defines the container. The evaporation material then melts and spreads within the container. The evaporation material on the surface of the wetted molten metal begins to evaporate, eventually stabilizing the amount of molten metal and the amount of evaporation. Furthermore, if the boat body is continuously energized while supplying the evaporation material (i.e., if the evaporation time on the substrate increases), the amount of molten metal may change. Through extensive research, the inventors of the present application have discovered that when the amount of molten metal changes due to the shunting of the current to the molten metal, the current value of the power supply also changes, and there is a correlation between the amount of molten metal and the current value.

[0009] In this invention, the average value of the state quantity detected by the detection means per unit time is calculated, and the power supply is controlled based on each successively calculated average value (e.g., the difference between the average values) to change the electrical characteristics. For example, when a constant-voltage control power supply is used as the power supply, the change in current value due to a change in the amount of molten metal is experimentally calculated in advance, and based on this, a current correction value required to maintain the same amount of molten metal is stored in advance in the memory of the control unit. During deposition, the current values ​​detected per unit time are smoothed to sequentially calculate the average value, and a correction value is determined based on the difference between successively calculated average values ​​to correct the current value. This minimizes fluctuations in the amount of molten metal during deposition over a predetermined period of time without the need for additional equipment, thereby effectively suppressing splash adhesion to the deposition target.

[0010] The present invention will be described in detail below with reference to the accompanying drawings, in which: FIG. 1 is a schematic cross-sectional view of a vacuum deposition system according to an embodiment of the present invention; FIG. 2 is a flow chart illustrating correction control of a current value; FIG. 3 is a graph illustrating correction control of a current value; and FIG.

[0011] Hereinafter, with reference to the drawings, an embodiment of the vacuum deposition system and vacuum deposition method of the present invention will be described using as an example a case in which a deposition target is a sheet-shaped substrate Sw, a deposition material Em is made of aluminum formed into a wire shape, and the deposition material Em is supplied and evaporated while its electrical characteristics when energized by a power source are taken as a current value (state quantity), thereby depositing an aluminum film on one surface of the substrate Sw in a vacuum chamber in a vacuum atmosphere. In the following, terms indicating directions such as up and down are based on Figure 1, which shows the installation position of the apparatus.

[0012] 1, the vacuum deposition system 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.

[0013] 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 is integrally formed by pressing a metal plate having a higher melting point than the evaporation material Em. Examples of high-melting-point metals include boron nitride, molybdenum, tungsten, and tantalum. 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. Note that the method of attaching the evaporation boat 3 to the electrodes via the electrode mounting plates 32, 32 is not limited to this, and other known methods can be used.

[0014] 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 defining the recess 31a in a horizontal position. 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. The evaporation chamber Vs is equipped with a material supply unit 6 for continuously or intermittently supplying wire-shaped evaporation material Em to the recess 31a of the boat body 31.

[0015] The material supply unit 6 includes a feed roller 61 installed on the side of the deposition prevention plate 13 arranged in the deposition chamber Vs facing away from the deposition boat 3, a motor 62 that rotates and drives the feed roller 61, and a pair of upper and lower guide rollers 63, 63. A through hole 13a is provided at a predetermined position in the deposition prevention plate 13, through which a wire-shaped deposition material Em is inserted. A guide tube 64 of a predetermined length with its tip bent downward is attached to the surface of the deposition prevention plate 13 that faces the deposition boat 3 and surrounds the through hole 13a, so as to guide the deposition material Em toward the recess 31a of the boat body 31. The deposition material Em is formed to an outer diameter of 1 mm to 5 mm and is wound around the feed roller 61 in advance.

[0016] The vacuum deposition system ES includes a control unit Uc. The control unit Uc is a known device having a microcomputer, a sequencer, a memory, and the like, and controls the operation of operating parts such as the vacuum pump Pu, motors 21a and 21b, motor 62 of the material supply unit 6, and constant-voltage controlled power supply Ps. The control unit Uc also receives as input a current value measured by an ammeter Am, and controls the constant-voltage controlled power supply Ps based on this input. A vacuum deposition method using the above-described vacuum deposition system ES will now be described.

[0017] When using the vacuum deposition system ES to deposit an aluminum film on a sheet-like substrate Sw in a vacuum chamber 1 under a vacuum atmosphere (i.e., in 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 using a constant-voltage control power supply Ps. After a predetermined time has elapsed, the motor 62 rotates the feed roller 61 to feed out the wire-like deposition material Em at a predetermined speed. As a result, the tip Em1 of the deposition material Em abutting the bottom plate of the boat body 31 defining the storage section 31a gradually melts and spreads, and the deposition material Em on the wetted and spread surface evaporates. Simultaneously, the motors 21a, 22a of the transport unit 2 are rotated to feed out the sheet-like substrate Sw at a constant traveling speed. As a result, the evaporated deposition material Em adheres to the portion of the sheet-like substrate Sw wrapped around the can roller Cr, thereby 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.

[0018] During deposition on the sheet-like substrate Sw as described above, the amount of molten metal and the amount of evaporation are initially stable. However, as the deposition time increases, the amount of molten metal Em may change. For example, a decrease in the amount of molten metal may occur because impurities precipitate on the outer periphery of the molten metal over time, depositing without re-evaporating (such impurities may also deposit in the molten metal). This deposit may block the wetting and spreading of the deposition material, narrowing the surface area of ​​the molten metal and reducing the amount of molten metal. On the other hand, an increase in the amount of molten metal may occur because the supply position or supply rate of the deposition material Em to the bottom plate 31a of the boat body 31 changes for some reason during deposition. The inventors' extensive research has led to the discovery that when the amount of molten metal changes due to the shunting of the current from the constant-voltage control power supply Ps to the molten metal, the current value of the power supply also changes, and there is a correlation between the amount of molten metal and the current value.

[0019] In this embodiment, the change in current value associated with changes in the amount of hot water is experimentally determined in advance, and based on this, the current correction values ​​(positive and negative correction values) required to maintain the same amount of hot water are calculated and stored in advance in the memory of the control unit Uc as table data. The average current value (A) as a state quantity detected by the ammeter Am per unit time is then calculated, and the constant-voltage control power supply Ps is controlled based on the respective average values ​​calculated successively to change the current value as an electrical characteristic. The current value control will now be described in detail with reference to Figures 2 and 3.

[0020] As shown in FIG. 2, after a predetermined time has elapsed since the start of deposition of an aluminum film on the sheet-like substrate Sw, the control unit Uc initiates current value control (S11). First, the elapsed time is reset (S12), and then counting begins. During this time, the current values ​​measured by the ammeter Am are input to the control unit Uc (S13). After a preset measurement time (the periods indicated by T1 and T2 in FIG. 3) has elapsed (S14), the current values ​​measured during the period T1 are smoothed by a known method to calculate an average value (S15). This average value is set as the current value sd2, and the previously calculated average value sd1, which is stored in advance, is updated. The current value sd2 is then compared with the previous value sd1. If the current value sd2 is greater than the previous value sd1 (S17), i.e., if the current value sd2 during the period T2 is greater than the previous value sd1 during the period T1 as shown in FIG. 3, it is determined that the amount of hot water is increasing, and current value reduction control is implemented (S18).

[0021] In the current value minus control, a minus correction value in the table data is determined based on the difference between the current value sd2 and the past value sd1, and the constant voltage control power supply Ps is controlled accordingly to change (decrease) the current value. For example, when the difference between the current value sd2 and the past value sd1 is +10, the current value is decreased by 0.2 A, and when the difference is +5, the current value is decreased by 0.05 A. The correction value may also be determined based on the range of the difference between the current value sd2 and the past value sd1. On the other hand, when the current value sd2 is smaller than the past value sd1 (S19), it is determined that the amount of hot water is decreasing, and current value plus control is performed (S20). In this case, in the current value plus control, a plus correction value in the table data is determined based on the difference between the current value sd2 and the past value sd1, and the constant voltage control power supply Ps is controlled accordingly to change (increase) the current value.

[0022] According to the above, during vapor deposition on the sheet-like substrate Sw, the current values ​​detected per unit time are smoothed to sequentially calculate average values, and the current value is corrected according to the difference between each successive average value. This makes it possible to minimize increases or decreases in the amount of vapor deposition material Em over a predetermined time period without the need for additional equipment. As a result, the amount of splashes adhering to the sheet-like substrate Sw due to increases or decreases in the amount of vapor deposition material Em can be effectively reduced, thereby maintaining a high product yield. To confirm this effect, the following experiment was conducted using the above-mentioned vacuum vapor deposition system ES.

[0023] In this experiment, the deposition boat 3 was made of boron nitride, and wire-shaped deposition material Em, made of aluminum with a diameter of 2 mm, was supplied by the material supply means 6 at a supply rate of 565 mm / min. Furthermore, a constant-voltage control power supply Ps was used to set the voltage applied to the deposition boat 3 at 9.0 V. The ratio (%) of the amount of molten aluminum relative to the deposition time was measured for the cases where the current value control was performed (inventive experiment) and where the current value control was not performed (comparative experiment). As shown in Figure 4 , in the comparative experiment indicated by the -●- line, the ratio (%) significantly decreased with increasing deposition time, whereas in the inventive experiment indicated by the -○- line, it was confirmed that the ratio (%) remained the same even with longer deposition times. Furthermore, in the inventive experiment, the amount of splash adhering to the deposition target was reduced by approximately 70% compared to the comparative experiment.

[0024] 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, the deposition material Em is made of aluminum, but the present invention is not limited to this. The vacuum deposition method of the present invention can be widely applied to any method in which the electrical characteristics change when the amount of deposition material Em changes during deposition, and there is a correlation between the amount of deposition material Em and the electrical characteristics. For example, the deposition material Em is made of copper. Furthermore, while the deposition target is a sheet-shaped substrate Sw on which an aluminum film is formed, the deposition target is not limited to this, and the present invention can be widely applied to deposition on substrates such as glass or silicon wafers with a predetermined contour.

[0025] In the above embodiment, the current value (A) detected by the ammeter Am per unit time is averaged, and the constant-voltage control power supply Ps is controlled based on the successively calculated averages to change the current value as an electrical characteristic. However, this is not limited to this. For example, the hot water volume can also be controlled based on the change in the slope of the current value per unit time. Specifically, the slope of the current value change (current value / time) associated with changes in the hot water volume can be experimentally determined in advance, and the current correction values ​​(positive and negative correction values) required to maintain the same hot water volume can be calculated based on this slope and stored in advance as table data in the memory of the control unit Uc. The average slope of the current value (A) detected by the ammeter Am per unit time, which fluctuates slightly from moment to moment, can then be averaged, and the constant-voltage control power supply Ps can be controlled based on the successively calculated slopes to change the current value as an electrical characteristic. In this case, the current slope is compared with the past slope. If the current slope is larger than the current slope, it is determined that the hot water volume is increasing, and negative current control is performed. On the other hand, if the current gradient is smaller than the current gradient, it is determined that the amount of hot water is decreasing, and current value increase control is performed.

[0026] In the above embodiment, a constant-voltage controlled power supply Ps is used as the power supply, and the electrical characteristic as the state quantity is the current value measured by the ammeter Am. However, this is not limited to this. A constant-current controlled power supply may be used as the power supply, and the state quantity may be the voltage value. Alternatively, a constant-power controlled power supply may be used, and the state quantity may be either the voltage value or the current value. Furthermore, regardless of the type of power supply, a change in resistance value may be utilized. Furthermore, in the above embodiment, a change in the current value as the electrical characteristic is controlled by controlling the constant-voltage controlled power supply Ps. However, this is not limited to this. In addition to or instead of changing the electrical characteristic, the motor 62 of the material supply unit 6 may be controlled based on the average values ​​to change the supply rate of the evaporation material Em, thereby increasing or decreasing the amount of molten metal.

[0027] ES...vacuum deposition system, Em...wire-shaped deposition material, Em1...tip of deposition material, Ps...constant-voltage control power supply (power supply), Uc...control unit, Sw...sheet-shaped substrate (substrate to be deposited), 1...vacuum chamber, 3...deposition boat, 31...boat body, 31a...recess (container for deposition material), 6...material supply unit, Am...ammeter (detection means).

Claims

1. A vacuum deposition system for evaporating a deposition material in a vacuum chamber under a vacuum atmosphere and depositing it on a substrate to be deposited, comprising: a deposition boat having a boat body with a storage portion for the deposition material and electrode mounting plate portions projecting from both ends of the boat body; a material supply unit for supplying a wire-shaped deposition material from above so as to contact the bottom plate of the boat body defining the storage portion; a power source for energizing between both electrode mounting plate portions to heat the boat body; and a control unit. The system further includes a detection means for detecting, as a state quantity, an electrical characteristic when energized by the power source, which changes in accordance with the amount of molten metal when the deposition material melts and spreads wet in the storage portion. The control unit is characterized in that it obtains an average value of the state quantity detected by the detection means per unit time, and controls the power source based on each average value obtained successively to change the electrical characteristic.

2. The vacuum deposition system according to claim 1, wherein the control unit controls the material supply unit based on each average value to change the supply rate of the deposition material, in addition to or instead of the change in the electrical characteristic.

3. A vacuum deposition method for evaporating a deposition material in a vacuum chamber under a vacuum atmosphere and depositing it on a substrate to be deposited, comprising: using a deposition boat having a boat body with a storage portion for the deposition material and electrode mounting plate portions projecting from both ends of the boat body as a deposition source, energizing between both electrode mounting plate portions to heat the boat body, and supplying a wire-shaped deposition material from above so as to contact the bottom plate of the boat body defining the storage portion. The method further includes detecting, as a state quantity, an electrical characteristic when energized by the power source, which changes in accordance with the amount of molten metal when the deposition material melts and spreads wet in the storage portion, obtaining an average value of the state quantity detected by the detection means per unit time, and further including a step of changing the electrical characteristic by the power source based on each average value obtained successively.

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