JPH0317795B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of coating a substrate with a substance brought into the vapor phase by electrical means. The deposition of substances from the vapor phase onto a substrate is well known in the art of coating technology and surface modification of substrates. Generally speaking, the base material to be transferred to the substrate is heated in the region of this substrate and is converted first into the molten state and then into the vapor phase. The material thus undergoes a two-phase transformation, ie from solid phase to liquid phase and then from liquid phase to gas phase.

Coatings are generally performed in a vacuum and usually require relatively high vacuum power to be applied to transfer vapor from the source to the substrate.

Early systems can utilize induction heating to perform the phase transformations described above.

The problem here is the application of metal to the substrate to be coated, especially ceramic substrates. Although many metals can be coated onto ceramics, refractory metals such as tungsten and titanium have hitherto been applied in less than satisfactory ways, and in virtually all cases the methods that have hitherto been utilized are There was a problem with adhesion.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for coating a substrate by depositing a substance onto a substrate of large area and/or complex shape at relatively low energy costs and with improved uniformity. It is in.

It is also an object of the present invention to provide a method for rapidly coating complex and/or large-area substrate surfaces.

Yet another object of the present invention is to provide an improved method for applying metal coatings to ceramic substrates, thereby avoiding the problems of poor adhesion that characterize prior art systems.

These objects and others that will become apparent from the description below are achieved by the invention in the deposition method described below. This method of vapor deposition involves placing an elongated electrode, in particular a large area surface deposit of the substance to be vaporized, in lateral proximity to the surface of the substrate to be coated covering a substantial portion of the length of the electrode in vacuum; It is based on the discovery that an arc current of 50 to 90 amperes can be formed by striking an arc between one end of this electrode and a counter electrode with a voltage of 30 to 60 volts applied to the electrode.

Surprisingly, once you strike an arc when the two electrodes are far apart, the arc, part of the arc, or the thermal effect produced by the arc appears in a spiral around the long electrode, and generally gradually This appears to result in the evaporation of the material making up the electrode in a helical pattern moving away from the counter electrode.

The arc is not confined to the space between the two electrodes, but rather has a component or effect of spiraling away from the opposing electrode over a region of long electrode length, which is the most It is very surprising that the conductivity should move further away from the counter electrode, despite the fact that it seems to lie directly on the line between the two electrodes where the main part of the arc is supposed to be confined. be. This effect is caused by the appearance of a taper toward the counter electrode even though the long electrode, that is, the deposition electrode, originally had a uniform cross section, and the fact that the coating from the material of the deposition electrode onto the substrate is formed on the deposition electrode. This is evidenced by the fact that the arc can be observed at a considerable distance from the arc impact surface.

In fact, this effect continues to exist for some time, followed by extinguishing of the original arc, so that the electrodes are periodically brought into contact and separated to generate an arc and then extinguish it.

According to a feature of the invention, at the end of the electrode consisting of the material to be deposited remote from the ignition electrode, means are provided which are controlled to maintain the temperature of the material supply electrode typically within the range of 800° to 1000°. is provided, and the rate at which the substance evaporates from the substance delivery electrode under the lower voltage, lower current and temperature conditions of the present invention can be increased to 1.5 to 2.0 times the evaporation rate of the initial system. Practically all metals, alloys, carbides and silicides can be used to prepare material delivery electrodes. Carbides, borides, silicides and nitrides as well as metals and other alloys can be deposited on the substrate.

Although it is not completely understood why the evaporation rate of the material to be deposited is increased by the lower energy utilization of the present invention, the movement of the arc creates another pooled molten phase covering a larger area of the material delivery electrode. In fact, it is possible to evaporate the molten metal during thin film formation.

According to another feature of the invention, the principles described above are utilized in the application of metal coatings to synthetic resins, which are in the form of cabinets or housings for electronic components. Because the substrate is unaffected by the large area coatings applicable with the present invention, the present invention provides an electromagnetic Most surprisingly, it turned out to be very advantageous as it forms a shield.

The present invention applies pure silicon coatings or other protective coatings, such as silicon carbide, silicon nitride or boron nitride, which have heretofore been utilized in the melting of silicon in the production of single crystal bars to be drawn from molten silicon in the semiconductor field. It is very effective when applied to the surface of the substrate. Furthermore, the present invention can also be applied to ceramics with metal coatings, even if the applicable metals are nickel, tungsten, titanium, etc., which have conventionally been difficult to apply to ceramic substrates.
Even refractory metals such as tantalum can be used with improved adhesion. Although virtually any ceramic substrate can be utilized for the purposes of the present invention, the substrate, particularly in the case of ceramic substrates, may be sandblasted or otherwise blast-roughened so that the surface receives a coating. It is preferable to carry out a chemical treatment. The term "sandblasting" as used herein refers to the blasting of abrasive particles onto a surface, and these abrasive particles are generally made of metal particles, silicon carbide, silicon nitride,
It can be diamond fines, iron oxide, silicon dioxide or any other material that can be roughened.
The transfer gas may be air or any other available gas. In both cases, it is also advantageous to preheat the substrate in the vacuum chamber or prior to introduction into the vacuum chamber to a temperature below the melting point of the metal. However, the preheating temperature should be at least a few hundred degrees.

A ceramic coating according to the invention comprises two electrodes of different metals, preferably highly conductive and highly refractory metals, placed in close proximity to a substrate, preferably a ceramic body, and housing the electrodes and the substrate. This is done by creating an arc between these electrodes in a vacuum evacuation chamber. According to the invention, the electrodes are first given relative polarity, that is, one is given a positive polarity while the other is given a negative polarity, and metal is selectively removed from one of these electrodes. It is believed that a small amount of this latter metal is deposited on the second electrode at the same time.

When the polarity is then reversed, the metal evaporates preferentially from the second electrode, initially including a small amount of metal from the first electrode, which precipitates on top of it, resulting in a A mixed composition of metals is formed.

When applied to highly conductive metals, especially copper, but also gold and silver to ceramic substrates, the disadvantages hitherto encountered with respect to adhesion, especially after or during soldering or welding of conductive elements, are:
Prior to application of the high conductivity metal, the ceramic is coated with a refractory metal in a relatively small thickness, and this intermediate layer of the coating can be removed by sequentially coating the conductive metal.

More specifically, tungsten as a heat-resistant metal;
molybdenum, titanium or zirconium thickness,
That is, a 5 to 10 micron coating is deposited on the support and then copper, copper alloys, gold, silver, or some other non-refractory metal, i.e., with a boiling point substantially lower than that of the refractory metal being used, is deposited on the support. greater thickness of metal with, i.e. 0.001 to 0.02
It has been found possible to apply inch (approximately 0.025-0.05 mm) coatings.

If the two-electrode method according to the present invention is also used, it is possible to configure one electrode as a refractory metal and the other electrode as a non-refractory metal, and by adjusting the polarity of the electrode during vapor deposition, a specific metal can be deposited. It turned out that it is possible to control.

In accordance with the present invention, applying a thin refractory metal coating between a copper coating and a ceramic substrate can increase adhesion by more than 100 times with respect to the force required to separate the coating from the substrate, all other things being equal. was discovered.

The present invention allows the use of ceramic supports and also ensures that masking techniques can be used to form the deposit in any desired pattern.

According to an important feature of the invention, one of the two electrodes brought into close proximity to the substrate can be moved out of alignment with the other electrode and replaced by a replacement electrode, and the latter can be used to repeat the process. The method described additionally deposits at least one layer of third electrode metal on the second layer.

The above and other objects, features and effects of the present invention will become more readily apparent from the following description with reference to the accompanying drawings.

FIG. 1 shows that various metals or metal alloys, including heat-resistant and refractory metals, are evaporated to obtain a mirror-like protective coating on a support according to the present invention.
An apparatus is shown that utilizes a simple arc method to apply the coating to a substrate.

As is clear from Fig. 1, the basic device consists of the sixth
A depressurization chamber (not shown) similar to the decompression chamber shown can be provided, and in this chamber the metal electrode 1 is supplied toward the electrode body 2 by an electrode supply device 7 to form a pool 3 of molten metal. Ark 4 is blown away.

The electrode body (hereinafter also simply referred to as the main body) 2 is held in a fixture, that is, an electrode holder (hereinafter simply referred to as the holder) 5, and is connected to the electrode 1 and the main body 2 from a DC power source 9 via a conventional arc stabilizing circuit 8. An arc current is supplied across the

It has proven advantageous for the electrode 1 of relatively small cross section to be equipped with a temperature regulator 6 which prevents overheating of this electrode.

Since the cross-section of the body 2 is substantially larger than that of the electrode 1, a pool 3 is created in a recess 11 formed at that location in the body 2.

EXAMPLE 1 The device of FIG. 1 using an electrode 1 and a body 2 made of titanium, aluminum, tungsten, tantalum or copper produces metal vapor in a pool 3 by striking an arc at a temperature of 5,000 to 7,000 degrees. The pool crosses the substrate 10 at a distance of 10 to 15 cm and forms a metal coating thereon. Pool 3 can be formed by a mixture of the metals provided by electrodes 1 and 2, thereby depositing an alloy of the metals of the two electrodes on the substrate. Preferably the electrodes are composed of titanium, while the molten metal consists predominantly of aluminum, tungsten, tantalum or copper.

The apparatus of Figure 1 is a noncrucible device that produces a protective coating of carbide without substantial modification.
It can also be used in processes to form silicide coatings on substrates, or to form carbide or silicide and even silicon carbide layers on substrates. In order to deposit a silicon carbide-tungsten carbide layer on the substrate, electrode 2 is composed of graphite and electrode 1 is composed of tungsten silicide. Decompression was initially reduced to 10 ^-6 Torr, and
Keep below 10 ^-5 torr. The DC arcing voltage is 100 volts and the arcing current is 150 amperes. Precipitate forms at a rate of approximately 0.2 g/min.

In this case, the apparatus of FIG. 1 is again used in a conventional vacuum chamber, but electrode 1 can be composed of silicon or carbon, whereas electrode 2 is composed of the metal whose silicide or carbide is to be formed. In the case of vapor deposition of silicon onto the substrate, it can also be composed of silicon.

For example, if it is desired to deposit silicon carbide onto a gas 10, electrode 1 need only consist of silicon, while electrode 2 is a block of carbon in which a pool 3 of silicon and a solubilized silicon carbide are deposited. Receive carbon.

The vapor transfers to the substrate and is deposited thereon as a silicon carbide layer. The substrate may be titanium, and the deposit formed on the substrate may be a mixture of titanium silicide and titanium carbide.

Alternatively, if the electrode 1 is composed of silicon or carbon and the electrode body 2 is composed of titanium, titanium carbide or silicide can be deposited on a substrate of a different composition.

If a slight oxidizing atmosphere is supplied into the decompression chamber,
A silicon dioxide precipitate forms on the substrate.

The apparatus of FIG. 1 is clearly particularly effective in the manufacture of semiconductors.

Two temperature regulators 6 may be provided along the length of the electrode 1, and an additional temperature regulator may be provided for the electrode body 2 to prevent it from overheating.

When either the electrode 1 or the body 2 is composed of silicon and the other of carbon, the reaction produces silicon carbide and precipitates with a higher purity than the original silicon and carbon. .

If both electrodes are composed of silicon, dense silica and silicon precipitates can be obtained, which is particularly desirable for coating semiconductors.

The device in Figure 2 is similar to that in Figure 1, but
It operates on a slightly different principle. That is, evaporation takes place at least partially from the wet upper electrode 101.

In this figure, corresponding reference numerals that differ only in the 100th digit are used for elements corresponding to those in FIG. 1.

In FIG. 2, the electrode supply device 107 is connected to a vertical reciprocating device 112, which is connected to the electrode 101.
The electrode 10 is rotated so that the tip thereof is periodically dipped into a pool 103 of molten metal formed within the electrode body 102.
1 is given reciprocating motion in the direction of arrow 114.

When the arc 104 is withdrawn from this pool for restriking, the coating 113 of molten metal on the electrode 101 evaporates and the deposit is deposited on the substrate 110.
formed on top.

Electrode body 102 is shown within holder 105;
The supply of arc current is then carried out by means of a DC power supply 109 and a stabilizer 108 according to the method described, and the electrode 101 is equipped with a temperature regulator 106.

This system, in a modification of the previous example, has electrodes 101 made of titanium and pools 10
It is particularly effective if 3 is made of aluminum.

Illustrated in FIG. 3 is an embodiment of the invention in which steam is deposited onto a substrate 210 disposed below a crucible 217, the crucible having an open top containing molten metal 203. It has a ring shape and is mounted in a holder or frame 205.

Here the upper electrode 201 has the shape of a spherical part, which acts as a reflector, so that the arc 204 is connected to the electrode 201 and to the crucible 217.
When the steam is ignited between the melt in the arrow 21
9 and then reflected downward to the substrate 21 as shown by arrow 218.
concentrated on 0.

The DC power supply 209 is the arc stabilizer 20 here.
The upper electrode 201 connected between the electrode 201 and the crucible 217 via 8 and mounted on the rod 216 is vertically positioned by a feeding device 207, while an auxiliary mechanism adjusts the position of the electrode 201 over the evaporated metal. It is positioned horizontally by 215.

In this embodiment, electrode 201 is titanium,
It may be composed of molybdenum or tungsten, while the molten metal may be composed of aluminum or copper, and the crucible 217 may be composed of graphite.

Another embodiment of the invention is shown in FIG. 4, where the vapor flows downwardly and is deposited on a substrate 310.

In this case, the open top crucible 317 containing the molten metal 303 may be supplied with another molten metal from a ladle or other source, indicated at 322, or from solid metal being melted within the crucible 317. . The latter solid metal can be heated by auxiliary means, for example an induction heating device 323, which is supported in the holder 305.

The bottom of the crucible 317 is provided with an opening 321 through which droplets of molten metal emerge, and these droplets are evaporated by an arc 304 ignited between the electrode 301 and the bottom of the crucible 317. It is something.

The temperature in the area of the arc is controlled by the auxiliary induction device 32
4 and the electrode 301 can be cooled as represented by the cooling element 306.

The electrode 301 is supplied toward the crucible 317 by an electrode holder 307, and the arc is maintained by an arc stabilizer 308 connected to a DC power source 309.

In this embodiment, the molten metal may be copper.

Instead of the auxiliary device 324, the substrate to be coated can also be provided at this location, for example in the form of a titanium ring, which can collect the vapor in the form of a coating.

The present embodiment of FIG. 5 vaporizes molten metal as it forms within a closed space;
This vapor is released onto the substrate 410 via opening 425.

In this case, a pool of liquid is created by melting an electrode 402 supported by a holder 405 by supplying a counter electrode 401 by an electrode supply device 407 via a central bore 426 in this electrode 402. and this electrode 40
1 passes through an insulating sleeve 427 forming the chamber. A temperature regulator 406 is placed coaxially around the two electrodes adjacent to the arc 404 to open the aperture 42.
Prevent overheating of the front area of 5. The precipitate is the substrate 4
10.

The current is connected to the arc stabilizer 408 and the DC power supply 4.
09, and is supplied between the electrodes by the method described above.

Figure 6 shows the reflectivity, using the principle explained earlier.
A miniature voltaic arc apparatus is shown for depositing corrosion-resistant, protective and semiconducting type metal, silicide and carbide coatings.

The device includes a vacuum chamber 500 with a handle 530 formed at its upper end to allow the portable unit to be easily transported.

This chamber is provided with a hollow sphere 517, the lower part of which forms a crucible for the molten metal 503, the interior of which is coated with a high temperature (refractory) material, such as aluminum oxide.

The top of the sphere is coated at 531 with a reflective layer that concentrates the heat reflected from the bath and sends it back to the bath.

An arc 504 is ignited between electrode 501 and bath 503, which is fed by unit 507 towards the bath as its electrode material is depleted.

Another metal, for example in solid form, is supplied to the bath as a rod 532, which is also connected to a supply device 533', so that when the bath is depleted, another metal is supplied to it.

Electrode 501 and bath 503 are connected to opposing terminals of an arc stabilizer and a DC power source in the manner previously described.

Tubular electrode 502 surrounds rod 532.

The lower part of the adapter 536 is provided with an air pump, indicated by reference numeral 533, which extends outwardly through a chamber containing the hollow sphere 517 and a vacuum hose 534 and a valve 535. Lateral opening 5 of sphere 517
An adapter 536 connectable to 25 is depressurized.

The chamber 500 is formed with a heating coil 537 to prevent undesirable vapor condensation onto the chamber.

Between the opening 525 and the adapter 536 is a vacuum lock 538 and a mounting device 539 for holding various adapters of different shapes and dimensions.
is provided.

Adapter 536 is also formed with a vacuum gasket 540 so that it can be supported against substrate 510 to be coated.

The small unit shown in FIG. 6 is brought to the location of the substrate 510 to be coated, and a suitable adapter 536 is pressed against the fixture 539 and the surface of the substrate 510 to be coated.
0. Arc current is applied and the device is evacuated by air pump 533, thereby melting the metal and forming bath 503 within the hollow sphere. Gate 538 is then opened and vapor is transferred at least partially to substrate 510 by a pressure differential as controlled by valve 535 held between the interior of sphere 517 and adapter 536.
It is something that allows you to move up.

In practice, any part of any product can be coated, and the use of a variety of adapters of different shapes and dimensions makes it possible to coat objects of even complex shapes without displacing the objects from the area where they are to be used. , possible. The device is collapsible for use in coating the inside of ducts and the like.

The device shown in the drawings is without adapter 536.
It can be used as a propellant for humans or equipment in space.

Once the arc occurs, the user simply needs to open gate 53.
8 to release the flow from the opening 525 and propulsion in the opposite direction. Air pump 533 is not required at all since the vacuum in space provides a natural vacuum for the device. In practical terms, all waste found in space applications can be stored in containers5.
17 can be utilized to generate this type of propulsion force.

FIG. 7 shows an embodiment of the invention, which combines the features previously described and the concepts developed above.

In the present apparatus, which can be used to deposit a coating 610' onto the inner surface 610a of a tube 610 forming a substrate of complex shape, a feed electrode 602 having a corresponding shape is placed on the inner surface 610a of the tube on the substrate 602a. It is centrally mounted and includes an induction heating coil 606a of a temperature regulator 606, which includes a thermocouple 606a.
A 06b or similar temperature sensor may be provided which responds to the temperature of the feed electrode with a conventional feedback control circuit to maintain the temperature of the feed electrode constant within the range of 800-1000°C.

As in the previous embodiment, the substrate and the source of material to be deposited thereon are enclosed within a vacuum chamber 600, which may be evacuated to 10 ^-6 Torr, thereby reducing the deposition to 10 ^-5 Torr. It can be done at a pressure of

At the end of the material supply electrode 602 an arc ignition electrode 601 is provided, which can be reciprocated towards and away from the electrode 2 by an electrically controlled reciprocating drive mechanism 607. The reciprocating drive mechanism is operable in response to zero current detector 607a, so that once the arc current has completely decayed, electrode 601 is moved to the left into contact with end 602a of electrode 602, and then pulled apart to re-establish the arc. Arc current is provided by a pulsating DC power supply 609 and an arc stabilizer 608 across it, with arc current and arc voltage parameters ranging from 50 to 90 amps and 30 to 60 volts by these circuit elements. adjusted within.

With a device that indicates that the arc has actually been blown once, the arc itself, evaporation effects, or other electromagnetic phenomena can cause the arc ignition position and the evaporation deposition over the entire length of the material delivery electrode 602, as shown by arrow A. The material supply electrode is subject to this phenomenon, i.e. over its length, and it remains effective until the arc decays at that location, which appears to generally proceed in a helical or spiral fashion.

The loss of material from electrode 602 gradually deforms it into a tapered shape, as shown by dashed line 602b in FIG.

The fact that this taper causes a retraction of the electrode from the substrate does not pose any serious problem. This is because the largest precipitate is in the area of greatest recession, so as it progresses along the substrate, the final coating will be very uniform.

The apparatus of the present invention is particularly useful in coating temperature sensitive materials with very thin coating materials. This is because this coating is particularly rapid and can be deposited without significant heating of the substrate.

Example 2 Copper electrodes 602 having the shape shown are placed in a support tube with an initial spacing of about 10 cm between the electrodes 602 from the support. The electrodes are maintained at a temperature of 900°C (approximately 482°C) and an arc is ignited at one end in the manner described above. The arc current is about 70 amperes and the voltage applied after pulling electrode 601 away to form the arc is about 40 volts. The evaporation rate from electrode 602 under these conditions exceeds the evaporation rate in Example 1.

FIG. 8 shows an arrangement for applying a silicon coating 710' to a quartz crucible 710 of the type used for melting silicon so that a single crystal bar of silicon can be pulled from the silicon melt, which is for subsequent slicing into silicon wafers and is used in the semiconductor industry. According to the invention, the crucible inner surface is sandblasted and the crucible is preheated, for example to a temperature of 200 to 600° C., before being placed in the vacuum chamber. A pair of silicon electrodes 701 and 70
2 are placed close to each other in the crucible and utilize an electrode reciprocating device of the type shown at 607, with the electrodes coming together and then separating as shown by arrows 707a and 707b, so that their electrodes contact and then pull apart to ignite the arc. A power supply, which may be of the type already described, is indicated at 709. Again the arc current is 50 to
90 amps and an arc voltage of about 30 to 60 volts. Particularly if the silicon is first heated, for example, by a method similar to that used in the embodiment of FIG. 7, a fairly uniform and very adherent silicon coating is obtained.

If a nitrogen atmosphere is released into the area of the arc, the precipitate consists of silicon nitride _SiN4 . If one of the electrodes is composed of carbon, silicon carbide precipitates are formed. The same system can be used to coat any substrate with pure Si or one of the other coatings mentioned above. After the initial arc is created, the electrode can be cooled.

FIG. 9 shows an apparatus for large area coating of a ceramic substrate 810, which sandblasts its coating-receiving surface prior to introduction into a vacuum chamber and then burns 810 along the underside of the substrate.
It may be preheated first by moving 20. Electrode 8
01 may be constructed from a refractory metal or nickel, and it is pushed via an actuator 807 into contact with and pulled away from a facing electrode 802, which may also be constructed from the same metal. It can be included.

The power supply is indicated by 809. The electrode is now mounted on a track 821 and moved along the substrate so that the arc is repeatedly ignited and
As a result of the arc traveling along the electrode 801 within the vacuum chamber containing the entire assembly, the entire surface of the substrate is coated using the principles described in FIG.

Example 3 Using an apparatus operating according to the principles shown in FIG. 9, an aluminum oxide plate is coated with 1 to 2 mils of tungsten using a tungsten electrode. Maximum electrode spacing approximately 4mm
About the arc current is 50 amps, the arc voltage is
It is 40 volts. The diameter of the electrode was approximately 1 cm.
The tungsten coating had a high degree of adhesion to the alumina plate.

FIG. 10 shows in a highly diagrammatic manner an apparatus for carrying out the method of the invention. This device generates a desired degree of vacuum using a suction pump 1011.
Chamber 1010 which can reduce the pressure to typically 10 ^-5 to 10 ^-6 Torr
It consists of: In this chamber, by a method not shown, a ceramic substrate 1012 is placed, and this is shielded by a mask, indicated schematically by 1013, so that the coating is produced only in the area defined by the window 1014 in the mask. be able to.

Inside the vacuum chamber, a portion of the substrate to be coated is placed in close proximity to a pair of electrodes, a copper electrode 1015 and a tungsten electrode 1016, which are equipped with devices such as electromagnetic motors (solenoids) 1017 and 1018. The electrodes are then briefly brought into contact to ignite the arc, and then pulled apart to separate them. A pulser that periodically excites devices 1017 and 1018 is designated by 1019.

The power supply comprises an alternating current power supply 1020 connected to a rectifier 1021 and the rectifier is equipped with a polarity inverter 1022 which, under the control of a timer 1023, converts electrodes 1015 and 10
The polarity of 16 can be reversed.

In an operation using a copper electrode 1015 of positive polarity and tungsten 1016 of negative polarity, the electrodes are brought into contact to preferentially evaporate tungsten such that the tungsten is removed from the mask 1013.
After depositing on the substrate via the window 1014 of
40 to 100 current of 30 to 100 amperes between the air gap
You can make an arc fly by passing it with a bolt. Coating period is timer 10
23, which reverses the polarity after the coating, which is on the order of microns in thickness, so that the copper electrode 1015 now turns negative polarity, while the tungsten electrode 1016 is made positive polarity, As a result, copper is evaporated from electrode 1015 and deposited onto the substrate.

As can be seen from FIG. 11, the article obtained includes a substrate 10 made of, for example, aluminum oxide.
30, which is copper coated 103
2 but separated by a thinner refractory metal coating 1031.

Example 4 Using the principle described, a current of about 70 amperes,
With a voltage of 80 volts and a vacuum of about 10 ^-5 Torr, the aluminum oxide plate is coated with tungsten about 8 microns thick and copper about 0.002 inch thick. The adhesion was measured and was 500 to 700 l _b /in ² (approx.
35 to approx. 49Kg/cm ² ) (force required to remove film)
It has been found that. When a copper coating of the same thickness is applied to the same substrate under the same conditions, the adhesion is ^only 6 to 8 _lb / ⁱⁿ² . Direct copper-to-ceramic joints have been found to be sensitive to both mechanical and thermal effects when making solder connections, whereas copper/tungsten contacts made in accordance with the present invention No such hypersensitivity was observed.

Practically identical results could be obtained by replacing tungsten with molybdenum, titanium and zirconium, and by combining these refractory metals with each other and using tungsten as an intermediate layer. Similarly, high degrees of adhesion have been obtained with alloys of nickel, gold, silver and each other and with copper.

FIG. 12 is a modification of the device of FIG. 10, in which a chamber 1110 is evacuated by a pump 1111.
contains a ceramic substrate 1112 to be coated with a plurality of metals. In this case, in addition to its actuator 1118 driven by a conventional electrode 1116 and a pulser/timer 1119, each actuator 1117 and 1117a is provided with a pair of counter electrodes 1115 and 1115a, each made of copper and gold, respectively.
The counter electrode assembly is mounted on a track 1124 having a drive mechanism which moves the electrode 111 in its displacement position according to the dash-dotted line.
5, the two electrodes can be moved to the left. Of course,
In its moved position, electrode 1115a is aligned with regular electrode 1116. As discussed in connection with FIG. 10, polarity reversal 1122 is again
The device is powered from an AC line 1120 via a rectifier 1121.

In this mode of operation, when the stagnation chamber is depressurized, actuators 1117 and 1118
is actuated to move electrodes 1115 and 1116 together and separate them to ignite the arc, with the tungsten electrode 1116 being of positive polarity while the copper electrode is being of negative polarity.

This process is continued in the manner described until the initial coating of tungsten has the desired thickness.

As can be seen from FIG. 13, this method not only results in erosion of the tungsten electrode 1016, but they also result in a small amount of precipitate 1125 on the copper electrode 1015.

If the polarities are reversed, i.e., the copper electrode 1015 is of positive polarity while the tungsten electrode is of negative polarity, the arc is ignited and the evaporation occurs from the copper electrode, the thickness is enlarged as shown in FIG. Some tungsten precipitate 1125 evaporates with the copper, resulting in a mixed tungsten/copper precipitate as a joint surface.

FIG. 14 shows a substrate 1112 coated with a tungsten layer, eg 1131. The copper coating 1132 is then mixed or mixed before applying the tungsten coating 1132 by continuing to generate vapor by arc ignition between the electrodes 1115 and 1116.
126 is applied to the substrate.

When the copper coating reaches the desired thickness, electrode assemblies 1115, 1117 are moved to the left to replace assemblies 1115a, 1117a and an arc is struck between electrodes 1115a, 1116 to deposit a layer of gold 1133 on the copper coating. is precipitated.

A controller 1127 may be provided for the electrode movement device 1124, pulser/timer 1119 and polarity reversal device 1122 and is controlled by a programmed microprocessor to reverse polarity and reverse polarity when the desired layer thickness is achieved. The electrodes may also be switched.

Example 5 The method of Example 4 is carried out except that all copper electrodes are replaced. 5 of gold under the conditions listed for copper deposition when using the same vacuum and similar arc ignition.
A flat coating in the micron order range was deposited on the copper coating.

It was found that the adhesion was not reduced and the gold layer obtained was an ideal contact for macroelectronic purposes. A study of the interface between copper and tungsten showed a mixed transition 1126 where evaporation of tungsten trace precipitates from the copper electrode was confirmed.

[Brief explanation of the drawing]

FIG. 1 is an elevational diagram showing an apparatus for performing vapor deposition according to one embodiment of the invention, and FIG. 2 is a similar view showing another apparatus, in which the vacuum-deposited material is oriented vertically. FIG. 3 is a diagrammatic vertical cross-sectional view of an apparatus for depositing a substance onto a substrate positioned below a pool of metal; FIG. 4 is another embodiment of the invention; FIG. FIG. 5 is an axial cross-sectional view similar to FIG. 3 showing an embodiment, FIG. 5 is an axial cross-sectional view of another apparatus for depositing substances on a substrate according to the invention, and FIG. FIG. 7 is a diagrammatic cross-sectional view of another apparatus for carrying out the invention; FIG. 8 is an axial cross-sectional view of a very compact compact apparatus; FIG. FIG. 9 is a diagrammatic cross-sectional view showing the application of a quartz crucible coating; FIG.
11 is a cross-sectional view of the product of the invention on a larger scale; FIG. 12 is similar to FIG. 10, but , a diagram showing another apparatus for carrying out the invention; FIG. 13 is a schematic side view showing the effect obtained during the deposition of metal on the first layer before applying the second layer; and FIG. Second
FIG. 3 is a cross-section through the product in layers; 1... Metal electrode, 2,102... Electrode body,
3,103 pool, 4,104,304,40
4,504...Arc, 6,106,406,6
06...Temperature regulator, 7,107,207,40
7... Electrode supply device, 10,210,310,4
10,510,602a,1030...substrate, 1
01,201...Top electrode, 109,209,3
09,409... DC power supply, 112... Vertical reciprocating device, 217,317... Crucible, 301,40
2,501,801,1015,1016,11
15, 1115a, 1116... Electrode, 710...
...Quartz crucible, 810, 1012, 1112...
Ceramic base, 1010...chamber.

Claims (1)

[Claims] 1. Bringing a pair of electrodes made of at least one component of a substance to be coated on a substrate close to the surface of the substrate ^; by reducing the pressure to a pressure of ⁶ Torr and maintaining the pressure in said space substantially no higher than 10 ^-5 Torr during the deposition, and intermittently bringing said electrodes into contact with and apart from each other. 30 to 30 at one end of each of the electrodes.
striking an electric arc between the electrodes at a voltage of 60 volts and a current of 50 to 90 amperes, thereby depositing material evaporated from the electrodes substantially uniformly onto the surface of the substrate; A method of coating a substrate, the method comprising: 2. At least one of the electrodes is made of silicon, and the method further includes the step of controlling the temperature of the one of the electrodes to maintain the temperature within a range of 800° to 1000° (about 427°C to about 538°C). A method according to claim 1, comprising: 3. The method of claim 1, further comprising the step of roughening the surface with blasting particles. 4. The method of claim 3 further comprising the step of preheating the substrate before igniting the arc. 5. Blasting the surface of the ceramic substrate with granules; preheating the substrate at a temperature of at least 200° C. and below the melting point of the metal coated on the substrate; evacuating a space in which the electrode is in close proximity to the substrate to a pressure of at most 10 ^-6 Torr, and during deposition the pressure in the space is substantially ^30-5 Torr at one end of each of said electrodes by intermittently bringing said electrodes into contact with and separating them from each other;
striking an electric arc between the electrodes at a voltage of 60 volts and a current of 50 to 90 amperes, thereby depositing material evaporated from the electrodes substantially uniformly onto the surface of the substrate; A method of coating a ceramic substrate with a metal comprising: 6. Claim 5, wherein the metal is nickel, copper, tungsten, titanium or tantalum.
The method described in section. 7. The method of claim 5, wherein said ceramic comprises alumina.