JPH06212408A - Metallic composition for melt evaporation and method for melt-evaporating metal - Google Patents

Abstract

PURPOSE:To control the temperature distribution in a hearth for the melt evaporation to a desired level and to efficiently perform the vapor deposition and the ion plating by allowing a metal to be evaporated having thermal conductivity of higher than a specified value and a material having a vapor pressure of lower than a specified value to coexist in the metallic composition used for the melt evaporation. CONSTITUTION:The metallic composition for the melt evaporation comprises a metal to be evaporated having >=80joule/m/sec/K thermal conductivity at the evaporation temp. and a material having <=10<-2>Pa vapor pressure at 2000K. Elemental metals such as Al, Ag, etc., or their compounds can be used as the metal to be evaporated, and W, etc., can be used as the material having <=10<-2>Pa vapor pressure at 2000K. A large amount of the metal to be evaporated can be rapidly melt-evaporated by performing the process at about 300 to 2500 deg.C melting and evaporation temp. of the metal, under about 1X10<-8> to 10Pa pressure.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal composition for melt evaporation and a method for melt evaporation of metal, and more specifically, for example, a metal composition for melt evaporation and metal for vapor deposition and ion plating. Related to the melt evaporation method.

[0002]

2. Description of the Related Art Conventionally, for example, in the electronics industry, and also in the surface processing of various metals and non-metals such as glass, plastic, paper and cloth, vacuum deposition and ion plating. Are widely used. In vacuum deposition and ion plating, in order to perform these industrially efficiently, a large amount of metal should be melted and evaporated as quickly as possible with a high degree of vacuum (hereinafter also referred to as vacuum). Is required.

Here, in the conventional metal evaporation method, when a metal having a relatively high thermal conductivity is evaporated and a charged particle beam is used, it is placed in a hearth (water cooling crucible) for melting the metal. , A hearth liner made of a substance such as graphite, which has a lower thermal conductivity than that of the hearth material and is difficult to react with molten metal, is installed, and the metal charged in the hearth liner is charged particle beam. Is irradiated to melt and evaporate the metal. However, with this method, the evaporation rate of the metal was slow and it was not satisfactory in practice. For example, using a 2.4 kW plasma, the hearth diameter is 72 mm, the molten metal temperature is 8
When aluminum was melt-evaporated at a temperature of 00 to 900 ° C., the evaporation rate was 1.7 × 10 ⁻⁴ kg / m ² / sec. Further, since aluminum has a high thermal conductivity, it can be melted and evaporated by an electron beam having a relatively low energy density using a pressure gradient type plasma gun (hereinafter referred to as UR gun). However, it is slow for practical use, and it is necessary to raise the temperature of the evaporation source in order to increase the evaporation rate, which requires heat insulation of the hearth. However, when trying to insulate with a hearth liner made of a heat insulating material such as graphite, the following problems occur. That is: a) If the power of the electron beam is increased to raise the temperature inside the hearth, the risk of bumping will increase, and if bumping occurs, the molten metal will scatter out of the hearth. Become. b) Since molten aluminum has a large reaction activity, it reacts with the hearth liner at high temperatures and shortens the life of the hearth liner, and the reaction product covers the surface of the metal to be evaporated and the evaporation rate. Will be reduced. In order to avoid such a problem, it is theoretically known that the temperature distribution of the contents in the hearth is relatively high in the central part and relatively low in the peripheral part, and the difference between them may be increased. . Nevertheless, for example, when aluminum or the like is used alone, the content in the hearth has a small temperature difference between the central portion and the peripheral portion and becomes substantially uniform, and the temperature distribution as described above is generated. I can't get it. Moreover, a specific means for forming such a temperature distribution in the contents in the hearth has not yet been known. This means that aluminum and other materials have a thermal conductivity of 8 at the evaporation temperature.
This is a problem common to vaporized metals of 0 Joule / meter / sec / ° K or more, and is particularly a problem when aluminum having a high reactivity is used as the vaporized metal.

[0004]

The present inventor has, for example,
In order to industrially and efficiently perform such processes in vacuum deposition and ion plating, a large amount of metal is removed under vacuum and at a relatively high temperature without reacting the metal to be evaporated with the constituent materials of the hearth liner. In order to melt and evaporate as quickly as possible, the temperature distribution of the contents in the hearth is relatively high in the central part and relatively low in the peripheral part. As a result, it is possible to make the temperature distribution of the contents in the hearth the desired temperature distribution by coexisting a metal to be evaporated such as aluminum and a specific substance. Based on this new finding, the inventors arrived at the present invention. That is, the present invention is a metal that can be melt-evaporated under reduced pressure and has a thermal conductivity at the evaporation temperature of 80 Joule / meter / sec / ° K or more and a vapor pressure at 2000 ° K of 10 or less. ^-A metal composition for melting and vaporizing, which comprises a substance of ² Pascal or less, and in a method of melting and vaporizing a metal under reduced pressure, the thermal conductivity at the vaporizing temperature is 80 joules /
A method for melting and evaporating a metal, characterized in that a vaporized metal having a rate of at least meters / second / ° K is melted and vaporized at 2000 ° K in the coexistence of a substance having a vapor pressure of 10 ^-2 Pascal or less.

In the present invention, the metal to be vaporized (hereinafter simply referred to as the metal to be vaporized) having a thermal conductivity at the vaporization temperature of 80 joules / meter / sec / ° K or more, preferably 80 to 10000 joules / meter / sec / ° K. (Sometimes noted)
Typical examples are substances containing a metal simple substance such as aluminum, silver, gold, and copper, a metal compound such as magnesium fluoride, and a metal compound such as cryolite (fluoride of sodium and aluminum). It is not necessary to apply the present invention to a metal having a thermal conductivity at the evaporation temperature of less than 80 Joules / meter / sec / ° K because the evaporation rate can be increased by the conventional method so as to be satisfactory for practical use.

In the present invention, the vapor pressure at 2000 ° K is 1
It is preferably as low as 0 ^-2 pascal or less, and the lower the better, the more preferable, but practically, a substance having a concentration of 10 ^{-10 -10 -2} pascal is preferable. This substance (sometimes referred to below as a promoting substance)
It is an element which belongs to the 5th period IV-VIII group or the 6th period IV-VIII group in the short-period element periodic table, and which has the above vapor pressure. Typical examples of the former are zirconium, niobium, molybdenum, technetium and ruthenium, and typical examples of the latter are hafnium, tantalum, tungsten, rhenium, osmium and iridium. 200
When a substance whose vapor pressure at 0 ° K is less than 10 ^-2 Pascal coexists, such a substance also evaporates and is mixed in a large amount as an impurity in the metal vapor or the vapor of the metal compound to form. This material is incorporated into the formed coating, resulting in a significant deterioration in the properties of the formed coating.

The ratio of the promoting substance to the metal to be evaporated is 0.1 to 10, preferably 0.5 to 2, by weight. If this ratio is less than 0.1 or exceeds 10, neither the amount of evaporation of the metal to be evaporated nor the evaporation rate at a relatively high temperature can be increased to a level sufficient for practical use, but this range is excluded. Does not prevent things.

The metal composition for melt evaporation in the present invention means that the metal to be evaporated and the promoting substance are in a mixed state at the time of melt evaporation, and the metal to be evaporated and the promoting substance are, for example, hearth. Prior to being loaded, they may be premixed with each other, or they may be separately fed to the hearth and mixed with each other in the hearth to form the composition.
The former is preferable in practical use. In addition, since this metal composition for melt evaporation forms an alloy upon cooling after melting, the melt of this metal composition for melt evaporation can also be said to be a precursor of the alloy (hereinafter, this melt evaporation). The melt of the metal composition for use may be referred to as an alloy precursor). Usually, melting and evaporation are continuously performed in the same hearth, but melting and evaporation can be performed in different hearths. In the latter case, it is not necessary to have a liner in the hearth used solely for evaporation.

In the metal melt evaporation method of the present invention, a charged particle beam is usually used as a heat source for melt evaporation. As the charged particle beam, an electron beam, a plasma ion beam or the like is usually used. A commercial product can be used as it is as a device for generating these beams. Above all, a pressure gradient type plasma gun is preferable. The charged particle beam used in the present invention may have a relatively low output, but it does not prevent the use of a charged particle beam having a relatively high output. Further, the operating specifications in the method for melting and evaporating metal of the present invention include the type of device for generating a heat source for melt evaporation, the types of evaporated metal and promoting substance used, the mutual ratios, and the loading amount in the hearth. It is different depending on the constituent material of the hearth liner and the like and cannot be specified in a general manner, but in practical use, for example, when a pressure gradient type plasma gun is used as a generator of a heat source for melt evaporation, it is as follows. That is, the temperature for melting and evaporating ... 500 to 2500 ° C., preferably 1500 to 2500 ° C., the pressure for melting and evaporating ... 1 × 10 ⁻⁸ to 10 Pascal (P
a), preferably 5 × 10 ⁻³ to 1 × 10 ⁻¹ Pa, power source for discharge applied voltage: 20 to 100 V (V), preferably 30 to 60 V, discharge current: 20 to 250 amps (A) Preferably, the magnetic field strength applied to the plasma is 40 to 100 A ... 20 to 50 G at the intersection of the center line of the plasma gun and the center line of the hearth. However, in the case of electron beam evaporation, the lower the pressure for melting and evaporating, the more preferable. As the metal melt evaporation device used in the present invention, a commercially available product can be usually used as it is.

The metal composition for melt evaporation and the method for melt evaporation of metal according to the present invention comprises a metal compound such as aluminum, silver, gold and copper and oxides, nitrides and carbides of these metals on the surface of glass and plastics. For example, when a metal luster is imparted to these surfaces by vapor-depositing them to form, for example, reflectors, ornaments, automobile parts and electric appliance parts, these surfaces are made electrically conductive to manufacture, for example, a condenser. In this case, when silver is deposited on the surface of the crystal for an oscillator to improve frequency characteristics and stability, and when gold is deposited on another metal thin film to form a gold coating, the coating is peeled off. It is preferably used when producing a gold foil by using

[0011]

EXAMPLES The present invention will be described in more detail with reference to an example using the metal melt evaporation apparatus shown in the longitudinal sectional view of FIG. 1, but the present invention is not limited to this example. . That is, the metal melt evaporation device shown in FIG.
A substrate holder 8 for supporting a substrate 7 to be vacuum-deposited on its lower surface is hung above the vacuum chamber 11, while a lower portion of a hearth (water-cooled) having a permanent magnet built therein is mounted on the lower portion thereof. A crucible 5 is provided, and the substrate 7 and the hearth 5 are separated by a shutter 6 interposed therebetween. Further, the vacuum chamber 11 is connected to the vacuum pump 3. Further, a plasma gun 2 for generating and irradiating plasma from the side surface of the vacuum chamber 11 via a plasma focusing coil 4 which is an air-core coil is provided. A supply hole for supplying the plasma working gas 1 to the vacuum chamber 11 is provided at the center of the plasma gun 2. In addition, a reaction gas introduction pipe 13 for introducing a reaction gas such as oxygen, nitrogen and acetylene into the vacuum chamber 11 which is used when forming a film of a metal compound is arranged so as to penetrate the wall of the vacuum chamber 11. It is set up. The plasma gun 2 and the substrate holder 8 are connected to a discharge power supply 9 and a bias power supply 10, respectively. The discharge power supply 9, plasma gun 2, hearth 5, and bias power supply 10 are all grounded.

The vacuum chamber 11 is usually made of aluminum alloy. Further, the inside of the hearth 5 is thermally insulated with a hearth liner, if desired. An UR gun is used as the plasma gun 2, and the plasma gun 2 is attached to the side surface of the vacuum chamber 11.
The plasma 12 generated from the plasma gun 2 is applied to the vacuum chamber 11 via the plasma focusing coil 4 and is further bent at a right angle by the permanent magnet in the hearth 5 to reach the hearth 5. The substrate holder 8 is isolated from the vacuum chamber 11 and also the bias power supply.
10 makes it possible to apply a bias voltage.

In the method of the present invention, this apparatus is used to form a metal or metal compound coating as follows. That is, for example, the substrate 7 to be vacuum-deposited.
Was mounted on the substrate holder 8, and after loading the melt-evaporating metal composition of the present invention into the hearth 5, the vacuum chamber 11 was evacuated to the base pressure by the vacuum pump 3.
A certain amount of argon as a plasma working gas 1 is introduced into the vacuum chamber 11 via the inside of the plasma gun 2.
After the inside of the vacuum chamber 11 reaches a predetermined pressure, the electron beam component 12 of the plasma generated by causing the discharge between the cathode of the plasma gun 2 and the hearth 5 to be vaporized metal composition in the hearth 5 is generated. The metal composition to be vaporized is melted by concentrating it to form an alloy precursor. The temperature of this alloy precursor is further raised, the vaporized metal is caused to start vaporizing at a vapor pressure corresponding to this temperature, and the vaporized vapor of the vaporized metal is directed to the substrate 7 in the vacuum chamber 11. Transition. When forming a film of a metal compound, when the evaporation rate of the metal to be evaporated and the temperature in the hearth 5 are both stable and reach a steady state, a reaction gas such as oxygen gas is supplied from the reaction gas introduction pipe 13. Introduced into the vacuum chamber 11. The introduced reaction gas and the vapor of the vaporized metal to be vaporized react with each other at a position spaced from the hearth 5 to generate vapor of the corresponding metal compound, and the vapor of the metal compound is , Board 7
Move further towards. When the plasma is stable and the reaction gas is introduced, after the reaction gas is introduced, the shutter 6
Then, the metal vapor or the vapor of the metal compound is allowed to pass therethrough, and the formation of the film of the metal or the metal compound is started on the surface of the substrate 7. In many cases, a coating (metal compound) formed by ion plating has good conductivity and thus a bias voltage is applied, but since an oxide of aluminum is an insulator, a bias voltage cannot be applied.

Example 1 Using the above-mentioned apparatus, aluminum was vapor-deposited on the surface of an aluminum alloy as a substrate. That is, the internal volume of the vacuum chamber 11 is 0.64 m ³ . Also hearth 5
The inside of the is insulated with a hearth liner made of graphite, and the internal volume is 100 cc. The distance from the tip of the plasma gun to the center line of the hearth is 290 mm. 70 g of aluminum and 70 g of tungsten were loaded in the hearth 5, and the pressure in the vacuum chamber 11 was adjusted to 5 × 10 ⁻⁵ Pa.
Then, argon gas was introduced from the plasma gun 2 at 40 SCCM (standard condition). As a result, the vacuum chamber 11
The internal pressure was 1 × 10 ^-1 Pa. 40V for discharge power supply
Is applied to the plasma gun 2 to generate plasma by heating the vaporized metal composition in the hearth 5 at 800 ° C. for 10 minutes to melt the alloy of aluminum and tungsten. The precursor was allowed to form. At this time, the plasma gun in the vacuum chamber 11
The strength of the magnetic field at the intersection of the center line of 2 and the center line of Haas 5 was 30 gauss. Next, when the alloy precursor is subsequently heated with an argon plasma obtained by increasing the applied current of the plasma gun 2 to 60 A, the temperature of the alloy precursor reaches 1940 ° C. The speed reached 4.7 × 10 ⁻³ kg / m ² / s. Further, the reaction between aluminum, which is the metal to be evaporated, and graphite, which is the constituent material of the hearth liner, was not substantially observed. At this time, the magnetic field strength at the intersection of the center line of the plasma gun 2 and the center line of the hearth 5 in the vacuum chamber 11 was 30 gauss. On the other hand, when aluminum was melted and evaporated in the same manner as described above except that only aluminum was used without coexisting tungsten, the temperature of aluminum in the hearth 5 was 800 to 9
It only rises to 00 ° C and the evaporation rate at this temperature is 1.
It was only 7 × 10 ⁻⁴ kg / m ² / sec. After that, as the heating time elapses, the aluminum reacts with the constituent materials of the hearth liner despite the relatively low temperature, the surface of the molten aluminum is covered with the reaction product, and the evaporation rate is Decreased with the passage of.

Example 2 Example 1 was repeated except that silver and copper were used instead of aluminum. The results are shown in Table 1. Table 1 Composition use Single metal use Ultimate temperature 2200 ° K 1200 ° K Silver 2.0 × 10 ^-1 1.6 × 10 ^-7 Evaporation rate ^* Copper 1.5 × 10 ^-3 1.3 × 10 ^{-8 *} Evaporation rate unit: kg / m ² / sec. Also in this example, the reaction between each of the metals to be evaporated, silver and copper, and graphite, which is a constituent material of the hearth liner, was the same as in Example 1. , Practically not recognized. From the results shown in Table 1, it is apparent that the coexistence of the promoting substance can markedly increase the evaporation rate of the metal to be evaporated.

[0016]

INDUSTRIAL APPLICABILITY By using the present invention in metal vaporization and evaporation performed in metal plating such as ion plating, even if the charged particle beam has a low output, the center portion in the hearth is compared. At a relatively high temperature, the peripheral portion produces a relatively low temperature distribution, and despite the relatively high temperature of the metal to be evaporated, the metal to be evaporated does not react with the constituent material of the hearth liner, and a large amount of material to be evaporated is not reacted. If it is possible to rapidly melt and evaporate the evaporated metal, and if plasma is generated and melted and evaporated with the same power as in the past, it is possible to greatly increase the evaporation rate of the evaporated metal. If the evaporation rate of evaporated metal is the same as the conventional one, power consumption can be saved, significant energy saving is possible, and metal deposition and ion plating can be performed efficiently. Can. Further, the metal melt evaporation method of the present invention is particularly preferably used when aluminum having a high reactivity with the hearth liner is used as the metal to be evaporated.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a metal melt evaporation device.

[Explanation of symbols]

 1 Plasma working gas 2 Plasma gun 3 Vacuum pump 4 Plasma focusing coil 5 Hearth (water cooling crucible) 6 Shutter 7 Substrate 8 Substrate holder 9 Discharge power supply 10 Bias power supply 11 Vacuum chain 12 Plasma 13 Reactive gas introduction tube

Claims (13)

[Claims] 1. A metal which is melted and vaporized under reduced pressure and has a thermal conductivity at the vaporization temperature of 80 Joules / meter / sec / ° K or more, and a vapor pressure at 2000 ° K of 10 ^{−. A} metal composition for melt evaporation, comprising a substance of ² Pascal or less. 2. The metal composition for melt evaporation according to claim 1, wherein the metal to be evaporated having a thermal conductivity at the evaporation temperature of 80 Joule / meter / sec / ° K or more is aluminum. 3. The metal composition for melt evaporation according to claim 1, wherein the substance having a vapor pressure of 10 ⁻² Pascal or less at 2000 ° K is tungsten. 4. A metal having a thermal conductivity of 80 joules / meter / sec / ° K or more at an evaporation temperature of 200 or more.
4. The ratio of substances having a vapor pressure of 10 ⁻² Pascal or less at 0 ° K of 0.1 to 10 by weight.
The metal composition for melt evaporation according to the item. 5. A method of melting and evaporating a metal under reduced pressure, wherein a vapor-deposited metal having a thermal conductivity at an evaporation temperature of 80 joules / meter / sec / ° K or more and a vapor pressure at 2000 ° K of 10 ^-2. A method for melting and evaporating a metal, which comprises melting and evaporating in the presence of a substance below Pascal. 6. The method for melting and evaporating a metal according to claim 5, wherein the metal to be vaporized having a thermal conductivity at the vaporization temperature of 80 Joule / meter / sec / ° K or more is aluminum. 7. The method for melting and evaporating a metal according to claim 5, wherein the substance having a vapor pressure of 10 ⁻² Pascal or less at 2000 ° K is tungsten. 8. The heat conductivity at the evaporation temperature is 200 Joules / meter / sec / ° K or more for a metal to be evaporated having a temperature of at least K
8. The method for melting and evaporating a metal according to claim 5, wherein the weight ratio of the substances having a vapor pressure at 0 ° K of 10 ^-2 Pascal or less is 0.1 to 10. 9. The temperature for melting and evaporating a metal is 300 to 2
The method for melting and evaporating a metal according to claim 5, wherein the temperature is 500 ° C. 10. The pressure for melting and evaporating metal is 1 × 10.
^-8 to 10 Pascals, The method for melting and evaporating metal according to any one of claims 5 to 9. 11. The method of melting and evaporating metal according to claim 5, wherein a charged particle beam is used as a heat source for melting and evaporating the metal. 12. The method of melting and evaporating a metal according to claim 5, wherein an electron beam or a plasma ion beam is used as the charged particle beam for melting and evaporating the metal. 13. The method of melting and evaporating metal according to claim 5, wherein a pressure gradient plasma gun is used as a device for generating a beam.