JP2008500454A - Vacuum deposition method and apparatus by evaporation of metal and alloy - Google Patents

Abstract

The present invention relates to a vacuum deposition method and a vacuum deposition apparatus by thermal evaporation of metals and alloys. The apparatus proposed in FIG. 1 comprises a melting crucible (1) having a molten metal (liquid metal) (2) and one or more crucibles (3) of an evaporation device (4) in a vacuum chamber (5). A heated liquid metal pipe (6) connecting the melting crucible to the evaporating crucible via a magnetohydrodynamic (MHD) circuit (7) with a fixed melt pressure. The circuit (7) includes an MHD pump (8), an area of the liquid metal pipe (6) adjacent to the MHD pump, heated liquid metal pipes (9), (10), and (11), and a liquid metal Connected to the area of the liquid metal pipe 6 in front of the MHD pipe via the pipe (11) and connected to the dilator (13) attached to the pipe (9) via the liquid metal pipe (10). A heating container (12). The space above the melt in the dilator and in the vessel is connected to a pipe (14) connected to a vacuum pump system (not shown). Two electrical sensors (15) of melt height L are attached to the dilator. The melt height L between the dilator and the evaporator is higher by Δh compared to the melt height L ₀ in the MHD circuit vessel, that is, the MHD pump has a pressure of Δh. Should be supplied. The technical solution of the present invention makes it possible to increase the stability of evaporation of metals and alloys in long-term processing, thereby increasing productivity. The above solution is used for the deposition of coatings having various functions in electrical, metallurgy and mechanical technology. Using the method of the present invention, it is possible to evaporate zinc, magnesium, cadmium, lithium, and magnesium galvanized alloys.

Description

Detailed Description of the Invention

  The present invention relates to vacuum deposition techniques, and mainly relates to plating a substrate by thermally evaporating metals and alloys in a continuous or semi-continuous operation apparatus.

  Intensive research on material evaporation methods and materials evaporation equipment for the deposition of anticorrosion coatings in metallurgy, active layers in chemical current source production, and coatings with various functions in electronics and other technical fields Has been. Mainly metals and alloys such as zinc, magnesium, cadmium, indium, and magnesium zincide are used for these purposes.

  Continuous evaporation of large amounts of these metals, measured in dozens and sometimes 100 kilograms, is necessary in industrial processes. It is difficult to maintain such an amount of evaporated metal at the evaporation temperature inside the vacuum chamber (in general, the temperature is not lower than 500 ° C.). Therefore, there is a problem in continuously supplying evaporated metal to a vacuum chamber without interruption for a long period of time.

  Well-known material delivery methods such as rods, wires, granules, or powders help a little to solve the above operational problems. When the substance reaches the evaporation device directly as powder or fine particles, heating the substance rapidly to the evaporation temperature results in the release of gas and also the dissolution and dissolution on the surface and inside of the powder particles and fine particles. . It adversely affects the quality of the coating of active materials, especially lithium. Supplying the material as a wire or rod also involves a slight release of gas. Apart from that, the deposition process inevitably hinders the preliminary replenishment of wires or rods.

  The method of supplying the substance to the evaporation apparatus in the melted state is substantially free from the above-mentioned drawbacks. The merit of the evaporation device for replenishing liquid metal is to evaporate low melting point metals such as lithium, indium, zinc, cadmium and some magnesium.

  G. Goncharov's Russian patent application 93026154 (December 27, 1996) discloses an apparatus for supplying liquid metal to an evaporator. The apparatus includes a metal melting furnace disposed outside the vacuum chamber, an evaporation apparatus disposed inside the vacuum chamber, and a pipeline connecting the metal melting furnace and the evaporation apparatus. The molten metal in the metal melting furnace is at atmospheric pressure. Feeding the molten metal to the evaporative dryer is accomplished by a pressure differential between the vacuum chamber and the surroundings. The height of the metal in the evaporator is firstly the sum of the atmospheric pressure and the pressure of the metal column in the metal melting furnace, and secondly, the metal column in the supply pipeline and the evaporator. Is defined by the balance between

  During operation of the evaporator without the replenishment of material in the melting crucible, the melt height is low in both the furnace crucible and the evaporator. This results in a reduction in productivity in the above device. This is because some of the generated vapor is concentrated on the crucible wall and does not reach the material directly. As a result, the metal is consumed, the height of the metal in the evaporator is changed, the evaporation pace is reduced, and the coating thickness in different areas of the substrate, such as a cylindrical object of film or metal foil, for example. Will change.

  Although the inventor refers to a melt level stabilizer in the evaporator, the ability of the stabilizer appears to be somewhat limited.

  It needs to be stressed that replenishment systems based on the action of atmospheric pressure are strongly limited by the density of the melt used. Therefore, to supply zinc, indium, and cadmium, the difference in melt height between the melting crucible and the evaporator should be at least 2.0-2.5 meters, for magnesium The difference in melt height should be 6 meters. On the other hand, the difference in melt height for lithium is 19 meters (!). Apart from that, it is not desirable for any metal to come into contact with the atmosphere for reasons of oxidation and slag accumulation, but for lithium, due to its immediate combustion, contact with the atmosphere is completely unacceptable.

  Another solution to the problem of supplying the liquid metal is to avoid contact of the molten metal with the air in the furnace crucible by sealing and pumping air. This leaves room for minimizing the overall dimensions of the delivery system and improving the purity of the melt in the melting crucible. For example, such a device is disclosed in E.I. Yadin's research paper (“Deposition of Coatings or Free Foils of Sublimating Metals”, SVC 40th Annual Technical Proceedings, 1997, p. 69). In this device, molten magnesium is supplied from the melting furnace to the evaporator by reducing the pump-down space above the melt in the melting furnace, and the ingress of inert gas into the space is controlled. Is done. The experience of operation of this device by the inventors of the present invention has shown that the wetting to wet the walls of the liquid metal pipeline and the evaporation element changes with a relatively small temperature change between the pipeline and the element. Revealed. Therefore, in order to prevent the evaporator from becoming full, it is necessary to adjust and maintain the pressure of the inert gas in the melting crucible with high accuracy. It is a disadvantage that it requires the production and use of a rather difficult adjustment system.

  Another solution is to maintain the height of the melt in the furnace crucible with mechanical assistance when the evaporator and the crucible are connected to each other, thereby increasing the height of the melt in the evaporator. Is to supply. Such a method for supplying molten metal by raising the melting furnace controlled by the height sensor of the molten metal in the evaporator is disclosed in Japanese Patent Application Laid-Open Publication No. Sho 62-267470 (publication date 1987). November 20, 2012, Yasuaki Sekiguchi) ”. In general, the furnace should have a sufficient amount of metal reserves, e.g. for performing a long evaporation cycle with one or several shifts. The heavy weight of the furnace causes significant problems with respect to the lifting operation of the furnace. Similarly, significant problems are associated with adjusting and maintaining the height of the melt in the evaporator.

  Published in Japanese Patent Publication “JP 09-053173 A (published February 25, 1997, Yasushi Fukui)” “Stable supply method of evaporating material” disclosed in “Stable supply method of evaporating material”. Technical solutions for maintaining the melt height are considered as prior art.

  Prior art devices are submerged in a melting crucible, a liquid metal pipeline, an evaporating dryer installed in a vacuum chamber, a melt height measuring instrument in the evaporating dryer, and the melting crucible melt. A body for controlling the height of the melt of the evaporative dryer, and a facility for controlling the depth of the submerged body. When the material to be deposited is consumed, the body is submerged in the melt by the measuring instrument signal. Accordingly, the melt height in the melting crucible and in the evaporating dryer connected to the melting crucible by the liquid metal pipeline remains stable.

  The above prior art solutions have significant drawbacks.

  It is entirely clear that the performance of the system is limited by the volume of the body that is sunk.

  After the body is completely submerged in the melt, the process is stopped, the body is raised to the initial position, the molten crucible with the molten metal residue is cooled, air is introduced, and new metal is loaded into the crucible. It is necessary to.

  The introduction of a melt height sensor into the evaporative dryer is another disadvantage of the prior art.

  Monitoring the height of the evaporative dryer melt, where the working temperature is above the metal melting temperature and the surroundings are filled with metal vapor, is a sensor that uses materials that can withstand the above conditions. Requires special protection.

  A further drawback in the prior art is that the above procedure pre-adjusts when both melting and feeding of the metal are performed from the same container, i.e. the melting crucible. This means that some impurities such as oxides, nitrides, and other compounds may accumulate in the melting crucible where the metal is vaporized due to various loadings. means. The melt and the impurities accumulate in the evaporative dryer and on the substrate that degrades the quality of the coating.

  The object of the present invention is to avoid the above drawbacks and to provide vacuum deposition with a constant productivity for the stability of the melt height in the evaporator, regardless of the amount of evaporated material. is there. To achieve the above objective, a magnetohydrodynamic (MHD) circuit including at least one vessel, a pipeline system and an MHD pump is placed between the melting crucible and the evaporative dryer.

  Separation of work steps between melting and maintaining the height stability of the melt in the evaporating crucible as well as refining a portion of the evaporated metal can be done entirely from one slag and accumulated impurities. It allows to be combined with a plurality of melting crucibles that are periodically deactivated for cleaning. Despite this, the operation of the evaporation system is not interrupted.

  The basic configuration and several embodiments of the proposed invention are shown in FIGS. Some components of the technical solution are given in more detail in FIGS. FIG. 1 shows a preferred embodiment of the present invention.

  FIG. 2 shows another simple embodiment of the technical solution when the deposition cycle is relatively short and there is no need for periodic replenishment of the system with molten metal.

  3-4 show a heating and cooling system for the liquid metal pipeline and the corresponding vessel.

  The proposed apparatus comprises a melting crucible 1 with a molten metal (liquid metal) 2 to be evaporated, one or more crucibles 3 of an evaporator 4 in a vacuum chamber 5, and an MHD circuit with a fixed melt pressure. 7 and a heated liquid metal pipe 6 connecting the melting crucible and the evaporating crucible through 7.

The circuit 7 comprises an MHD pump 8, the area of the liquid metal pipeline 6 adjacent to the MHD pump, the liquid metal pipelines 9, 10, 11 and the liquid metal pipe 11 of the liquid metal pipe 6 in front of the MHD pump. A heating vessel 12 connected to an area and connected to an expansion tank 13 attached to the pipeline 9 via a liquid metal pipe 10. The space above the melt in the heating container 12 and the expansion tank 13 is connected to a vacuum pump system (not shown) via a pipe 14. Two electrical sensors 15 of melt height L are installed in the expansion tank. The melt height L in the expansion tank and in the evaporator is higher by Δh compared to the melt height L ₀ in the MHD circuit vessel. That is, Δh is the operating pressure of the MHD pump.

  In a preferred embodiment, the substrate support 16 is in the form of a cooled rotatable drum. The substrate 17 to be coated is a cylindrical material. For example, although polymer films or metal foils can be applied to the present invention, they can also be adapted to other types of substrates by taking another form of anchoring and / or transport during the deposition process.

  The melting crucible 1 is connected to a vacuum pump system (not shown) by a branch pipe 18 and connected to an inert gas (for example, argon) supply system (not shown) by a branch pipe 19 to measure the pressure in the space above the melt. A measuring instrument 20 and a sensor 21 for measuring the height of the melt.

  The liquid metal pipe 6 includes a U-shaped elbow pipe, and an emergency cooling system (not shown) as an additional safety measure may be controlled.

  When the deposition cycle is relatively short, there is no need for periodic replenishment of the constant pressure circuit 7 during the cycle of supplying the evaporated metal to the melting crucible as described above. In this case, the simple embodiment shown in FIG. 2 may be used. In this embodiment, the heating vessel 12 of the constant pressure circuit 7 is removed, and the melting crucible 1 including the sensor is provided in the circuit 7 instead of the heating vessel 12. In this case, the expansion tank 13 is connected to the melting crucible 1 through the liquid metal pipeline 10, and the pipe 14 connects the space above the melt in the melting crucible and the expansion tank to the vacuum pump system. To do.

  The melting crucible 1, the heating vessel 12 if used, and the liquid metal pipelines 9, 10, 11 are heated using electricity in a common manner. Apart from that, each of the above components comprises a cooling pipe, preferably an air coiled pipe. The tube is also a fluidic device, and the tube is still difficult to manufacture and sometimes not acceptable for safety reasons, for example with lithium evaporation. The use of cooling tubes offers the potential for increased productivity because it reduces run-to-run operations. For simplicity, the heating and cooling system is not shown in FIGS.

  A cross section AA of the system for electrically heating and air cooling the melting crucible 1 and the heating vessel 12 of FIGS. 1 and 2 is shown in FIG. The system includes the melting crucible 1 or the wall 23 of the heating vessel 12, a resistance heater 24 electrically insulated from the wall, a heat insulating material 25, and an air cooling pipe 26.

  A cross-section BB of the system for electrically heating and air cooling the liquid metal pipelines 9, 10, 11 of FIGS. 1 and 2 is shown in FIG. The system includes a liquid metal 2, a liquid metal pipeline wall 27, a heater 28, insulation 29, an air cooling pipe 30, and an element 31 that bonds, eg welds, the air cooling pipe to the liquid metal pipeline.

  The apparatus operates in the following manner.

  The vapor deposition cycle begins after filling the MHD circuit 7 and its heating vessel 12 with metal 2 from the melting crucible 1. Meanwhile, it is possible to cool and open the melting crucible 1 and supply the next metal without interrupting the vapor deposition process. Of course, it is necessary beforehand to cool the pipeline section between the melting crucible and the MHD circuit below the melting point of the metal.

  The height of the melt in the evaporator 4 is monitored by the height of the melt in the MHD circuit 7 where the melt temperature is 30-50 degrees above the melting point of the metal. There is little metal vapor, which gives the operational reliability of the melt height sensor and the general system.

  The heating container 12 of the MHD circuit 7 is filled with the liquid metal 2 by a known method. For example, the melt is discharged from the melting crucible 1 by the pressure difference generated by the passage of an inert gas such as argon through the branch pipe 19 into the space above the melt to fill the circuit. It is a method (FIG. 1). When the MHD pump is started, filling of the liquid metal pipeline 6 and the expansion tank 13 is started. If the pressure is insufficient, the pipeline fills only part of its height. In this case, there is no circulation of the melt. As the pressure on the MHD pump increases, the melt gradually begins to fill an important part of the expansion tank 13. When the melt reaches height L, the melt begins to flow along the liquid metal pipeline 10 to the heating vessel 12. As a result, circulation of the melt in the constant pressure circuit 7 starts. The flow rate of the melt in the expansion tank 13 connected to the liquid metal pipeline 6 is greatly reduced, approaching the laminar flow specific speed.

  A column melt melt height sensor 15 in the constant pressure circuit provides a pressure signal. Therefore, the expansion tank 13 and the entire circuit 7 are not full in case of excessive pressure. The sensors in the circuit 7 together with a common aid allow for the supply of pressure constancy provided by the MHD pump, so that the melt height in the circuit is constancy. If now the area of the liquid metal pipeline 6 that connects the circuit 7 to the crucible 3 of the evaporative dryer 4 is heated to a corresponding temperature, the melt begins to fill the crucible and, in addition, in the liquid metal pipeline 6 and Since the operating pressure of the MHD pump in the liquid metal pipeline 9 is equal, the melt heights in both the circuit and the evaporator are equal.

It is well known from the experience of the inventor of the present invention that the internal pressure F of the pipe of the MHD pump required to maintain the required melt height is defined by the following equation.
F ≧ ρ · gΔh
Here, ρ is the density of the melt, g is the acceleration of gravity, and Δh is the operating pressure of the MHD pump.

Because of the evaporation of FIGS. 1 and 2, the melt height L ₀ tends to decrease by a certain value due to the decrease in the height of the liquid metal in the system. The sensor 15 can compensate for the decrease by sending a signal to the MHD pump to increase the pressure. This process may be automated by known means.

  A unique feature of MHD pumps that may reverse pressure in an instant is the additional merit of the proposed technical solution. This feature is useful during the evaporation of alkaline metals where contact with air is dangerous.

  Therefore, in the event of an emergency caused by an increase in pressure in the deposition chamber, it is possible to quickly empty the evaporation crucible by a corresponding replacement of the MHD pump 8.

  Failure to melt circulation and supply system sealing is also dangerous when operating with alkali metals. It carries the risk of spreading large amounts of melt in the vacuum chamber. It is therefore proposed to equip the evaporative dryer 4 with a melt supply pipeline 6 comprising a U-shaped elbow tube 22 with an emergency cooling system (not shown) in order to minimize the aforementioned aftermath. . This member, at the command of the system, quickly clogs the pipeline using a solid melt plug.

  For example, the apparatus shown in FIG. 1 shows a vacuum apparatus for a lithium coated polymer film by a lithium thermal evaporation method. Four steel crucible evaporative dryers are installed in the vacuum chamber of the apparatus. The lithium melting crucible is installed outside the vacuum chamber and connected to the evaporation dryer by a liquid metal pipeline. A liquid metal constant pressure circuit comprising an MHD pump, a container, and a pipe system is disposed on the upper part of the liquid metal pipeline. At the top of the circuit, two grounded and insulated rods are inserted and equipped with an expansion tank connected to the power supply and the control unit of the MHD pump. The bar can be moved vertically in the range of 10 mm to 15 mm.

  The above circuit is manufactured so that the height of the center of the lateral liquid metal pipeline exiting the expansion tank is equal to the desired height that fills the evaporation crucible with a melt of lithium. The lower part of the circuit is connected to a lithium melting crucible with a liquid metal pipeline.

  All members of the evaporative dryer supply system are divided into a heater that indirectly heats using electricity and a wall temperature sensor. A melting crucible is provided in a room adjacent to a vacuum apparatus that is maintained such that the relative air humidity does not exceed 2%. A lithium ingot weighing 840 grams is fed into a melting crucible with a relative air humidity of 2%. The initial amount of lithium was about 6.3 liters.

  The melting crucible pumping is started after its sealing. The pumping operation of the vacuum chamber and the constant pressure circuit is performed simultaneously with the pumping operation of the melting crucible. When the pressure in the melting crucible space reaches 2 Pascals, the heating is started and continued until the temperature is 250 ° C. Monitoring the temperature of the melting crucible wall determines when lithium melting begins, and the extent to which the melt fills the crucible is determined by the height sensor signal.

  The melting crucible pumping continues after melting is complete until the dissolved in lithium gas is removed. At the same time, the circuit is heated to 250 ° C. and the power supply unit of the MHD pump is in operation. After 3 hours, the melting crucible pump line is turned off and argon injection is started through fine adjustment of the inset valve. The beginning of the time when lithium reaches the circuit is recorded by the melting crucible height sensor signal. Lowering the height sensor to the rated depth makes it possible to determine when the circuit has been completed with lithium. The pressure of the MHD pump is gradually increased until the operation time of the sensor installed in the expansion tank of the circuit. The heating of the melting crucible and the liquid metal pipeline connected to the constant pressure circuit is then switched off and stopped, and the heating of the pipeline supplying lithium to the evaporator is started. , And continue to 250 ° C. When the temperature reaches a set point, filling the evaporation crucible with melt is observed through a visual device in the vacuum chamber.

  After heating the crucible filled with lithium to a temperature of 580 ° C., lithium deposition is performed on a 25 micron thick PET film pre-covered with 40 nm thick “Inconel 400”. The cycle for is started. The above process is continued for 5 hours without interruption to produce a product with a 300 m coating. It is regularly observed that the lithium height in the evaporating crucible remains unchanged.

  After completion of lithium deposition, the crucible heating is switched off and stopped and the lithium is cooled to 300 ° C. The MHD pump is then reversed and lithium is discharged into the circuit for 1 minute. In addition, the liquid metal pipeline connecting the circuit to the evaporator is switched off and supplied with compressed air to cool its wall and crucible. After achieving a temperature between 50 ° C. and 60 ° C., dry air is placed in the vacuum chamber, the coated cylindrical product is lowered, a new cylindrical object is placed, and a new cycle is started.

  The U-shaped elbow of the pipeline that supplies lithium to the evaporative dryer is constantly filled with metal, and after cooling the liquid metal pipeline, the elbow is connected to the hot circuit before air enters the chamber. It functions as a valve that prevents air from penetrating.

  Five similar deposition cycles were performed with one lithium, and a 1500 m coated product was produced for a chemical current source. The lithium thickness of all coated cylindrical objects has been shown to not vary by more than 5% and is typical for any vacuum deposition process. In spite of this, no constant decrease in thickness due to a decrease in melt height in the unloaded crucible is observed.

It is a figure which shows preferable embodiment of this invention. FIG. 6 shows another simple embodiment of a technical solution when the deposition cycle is relatively short and there is no need for periodic replenishment of the system with molten metal. FIG. 2 shows a heating and cooling system for a liquid metal pipeline and a corresponding container. FIG. 2 shows a heating and cooling system for a liquid metal pipeline and a corresponding container.

Claims (6)

Melting a metal and an alloy in a melting crucible provided outside the vacuum deposition chamber and connected by a liquid metal pipeline to an evaporation dryer provided in the vacuum deposition chamber;
Supplying the metal to the evaporation dryer;
Monitoring and maintaining the height stability of the liquid metal in the evaporative dryer;
Flowing the liquid metal with a magnetohydrodynamic pump in a liquid metal circuit;
Stabilizing the height of the liquid metal in the liquid metal circuit;
Supplying the liquid metal from the liquid metal circuit to the evaporation dryer;
And a step of stabilizing the height of the liquid metal in the evaporation dryer by the stabilized height of the liquid metal in the liquid metal circuit. A vacuum chamber having pump means;
An evaporative dryer having one or more evaporative crucibles and provided in the vacuum chamber;
A melting crucible provided outside the vacuum chamber and connected to the evaporative dryer by a liquid metal pipeline;
Stabilizing means for stabilizing the height of the melt in the evaporative dryer;
A liquid metal circuit having a magnetohydrodynamic pump, a circulation system of a heated pipeline and an expansion chamber, and a height sensor in the expansion chamber, which is connected to the evaporation dryer by the heated pipeline; A vacuum deposition apparatus using metal and alloy evaporation.   The metal and alloy evaporation according to claim 2, wherein the liquid metal circuit comprises a container for storing metal to be evaporated, and the melting crucible is provided outside the liquid metal circuit. Vacuum deposition equipment.   The vacuum deposition apparatus according to claim 2, wherein the melting crucible is provided in the liquid metal circuit.   3. The apparatus for vacuum deposition by evaporation of metals and alloys according to claim 2, wherein the wall of the element containing the liquid metal is provided with an air cooling tube.   3. The metal and alloy of claim 2 wherein the liquid metal pipeline between the evaporative dryer and the liquid metal circuit comprises a U-shaped elbow with an emergency cooling control system. Vacuum evaporation equipment by evaporation.

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