DE1771968A1 - Evaporation source for the precipitation of metals from the vacuum - Google Patents

Description

PATENTANWÄLTE I / / I 9 Q ö

DR. CLAUS REINLÄNDER DIPL.-ING. KLAUS BERNHARDT

D-8 MONKS 6Q BÄCKERSTRASSES ^

SYLTANIA ELBCIRIC PRODUCTS INC. Wilmington, Delaware V. St. v America

Evaporation source for the precipitation of metals from the vacuum

Priorities »August 10, 1967 United States of America US Serial Numbers 659 777 and 659 747

Summarized

It becomes an improved laydown source of evaporation of metals from the vacuum t "wrote a resistance heating element made of nested coils" melting metal wire. An elongated, heat-resistant " digee vessel with a cavity to accommodate the to evaporate = the metal is carried by the heating element and heated there is a barrier between the cavity and the heater, to prevent overflowing liquid metal from contacting the Heater to come into contact.

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State of the art

The invention relates to evaporation vessels for use in the coating of objects with metals, whereby the metal is reduced to its evaporation temperature under vacuum is heated and then deposited on the object to be coated, and in particular such an evaporation vessel which contains the metal charge to be evaporated, but did not form the heating element itself

Ready electrically conductive, heat-resistant heating elements have been used to heat metals such as aluminum, silver, Cadmium and the like to evaporate, but they suffered from very severe corrosion from the liquid to be evaporated Metals, or under thermal jumps due to the high loads drives tempera doors. In addition, the Heii & ement in Operation due to normal thermal breakdown, or because tension came on the solid element when the linden tree solid were pinched and not pinched in fully flexible mounting posts · element »of this type were made Graphite, titanium boride, titanium carbide and the like

There is also evaporation heat on the high-temperature wire alone manufactured, for example tungsten, molybdenum and tantalum,

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however, they generally had a short lifespan Corrosion of liquid metal, like aluminum that evaporates' wasο

Summary of the invention! .

According to the invention, a long-lived evaporation source is made available which is substantially resistant to corrosion is through the liquid metal to be vaporized and is not subject to cracks which are exerted on the element when its Ends are clamped in the electrical connection producing fastening post. It becomes an elongated evaporation « Vessel used, which has a cavity, the ver ° Contains steaming metal, and lieaes is made from a vessel It produces a heat-resistant material that works against the metal whose evaporation temperature a is corrosion-resistant. The container is carried and heated with a new type of resistance heater, which consists of a network of nested coils made of high-melting metal «The ends of the helper protrude over the ends of the vessel a hioaus and are with the retaining post connected to a vacuum deposition device and grounded by this is borne, and the stoker is flowing through it electric current heated »

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The flexibility of the network construction allows the heater to absorb stresses that result from thermal expansion or from small misalignments in the retaining posts to which the ends are clamped without damaging the heater d: These tensions are not transferred to the evaporation vessel because there is no strong connection between the vessel and the heater. The life of the evaporation source is thus extended iladureh that the error "source, such as metal corrosion reduced due Gefassen or terminal voltages werdenο

Another advantage of the inventive evaporation source is the uniformity of the slek-f; ric resistance, the main = depends mainly on the structure of the heating element. That can be done with semi-automatic controlled mass production facilities where it is desired to have substantially constant hoizer currents and Maintain precipitation rates even if the evaporation source be exchanged., This is not possible with the electric conductive, heat-resistant elements that have previously been used, because their resistance differs considerably from element to element

The heater itself is also exposed to corrosion from the metal, as already mentioned, and contact with the heater

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to prevent by overflowing liquid metal, will a lock is arranged between the cavity and the hoarse. This lock can be a protective sleeve around the heater, or a channel or the like in the surface of the vessel, with the overflowing metal from the exposed ends The heater is diverted away »Such a barrier also prevents corrosion of the heater from overflowing metal prevented0 so that the life of the invention «according to Source of evaporation is increased even further «.

The invention will be explained in more detail with reference to the drawing; show it:

Figo 1 is a perspective view of a Mefcallver = DampfungsquelIe according to the invention;

Figo 2 is a perspective view of the heating element, its central part only is indicated schematically;

3 shows the Uetz construction dus Heizelenentes;

4 is a perspective view of a second embodiment an inventive evaporation source;

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5 shows a further embodiment of the invention; and FIG. 6 shows the individual components of the embodiment according to FIG. 5.

A heat-resistant vessel 1 according to the invention consists of a refractory material that is substantially resistant to corrosion by the liquid metal being vaporized and is also practically inert to a heating element 4 at operating temperatures. A cavity 2 is on the top 6 of the Ge » arranged barrel and serves as a container for the to be evaporated Metal ο It is desirable to have the metal charge in cavity 2 on one To limit the amount that is suitable for semi-continuous operation without the need for too high a seed temperature The depth of the cavity 2 is therefore preferably less than 1/3 the depth of the vessel a 1. In the ideal case, the cavity 2 is central placed on the surface 6 in order to minimize the thermal stresses resulting from an unequal Wall thickness around the cavity 2 can result. A heater compartment 3 is in the lower part of the vessel 1 in its longitudinal direction arranged and has suitable dimensions, so that a rush » heater 4 can be used in this. For optimal warmth « transition from heater 4 to Gofäss 1 should be the cross-sectional area Compartment 3 should be as small as possible considering that the

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Heater 4 can be used easily. For preferred wines, the compartment 5 in the vessel 1 is also arranged in such a position that the thickness of the side wall © is essentially the same, in order to reduce thermal stresses; _s which can develop in vessel 1 from unequal wall thicknesses.

The mains heater 4 consists of individual coiled coils, first of all straight pieces of hole-melting wire are individually wound around a coil ₉ , each turn being separated from coiled coils so that individual coils are formed. After removing the core, two coils are threaded into each other, a third is threaded into the second, a fourth is felled into the third and this is continued until a wad of interlaced or nested spirals is obtained. The mat is then arranged longitudinally around an elongated peg so that the e: cete and the last helix lie next to one another, uni it is threaded through the first and last helix around the | e unite After the remover, from the zips rerdea the ßndes are welded _{p in} order to fix the helical ends securely and e: Ln iJategrales, flexible a heating element to load, iu the .lie individual bobbin winder can expand and contract freely. TIorzugtiweise wildly a rod 5 from the same fetall inserted into the ends of the heater uni

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there kept silent to keep the temperature of the ends below that of the Body of the heater during operation *

The heater 4 is then 80 in the compartment J of the vessel 1. set that substantially equal amounts of the heater 4 from protruding from the ends of the vessel 1 «The heater 4 does not fit just in the compartment 3, but there is a sufficient surface surface contact in order to force the vessel 1 to it prevent moving due to its own weight with respect to the heater 4 alone.

In operation, the ends of the heater 4 with the vessel 1 carried by it are clamped to holding posts and other holding devices in order to supply electrical power to the heater 4 in a vacuum chamber is brought into a line of sight with the cavity 2, the rising metal thereof "di.ß vapor condenses on the article and niederschlägtο a batch of the metal to be evaporated a" is gebraoht into the cavity 2 and the pressure in the akuumkammt ^v: r If the dome heater 4 is then reduced to less than 0.001 Torr, sufficient electrical power is supplied to heat the metalloharge at chamber pressure to a temperature such that the metal evaporates at a reasonable rate and becomes on the opposite side

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inside the chamber niederechiagto In a coating process, for example if a continuous roll of plastic film is to be coated with aluminum, provision is made in the vacuum chamber ₉ that the film can be continuously unwound from a roll ₉ ffbes? . happened && n cavity 2 and the coated S is wound ¹ Olie on #iasr Spale while the aluminum kontiaiaierlieh tos "" evaporated, the source of aluminum for the cavity 2, a coil of aluminum wire in d £ - ⁱ r chamber wofeei the free © of the wire is directed into the cavity _o the wire wise suitably rate of dor coil unwound "s @ -DSS a substantially constant charge gsaühmolzenes Alwaim & wm remains 1 @ cavity, d" h _e about the Verdampflangerste nit aluminum ο the heater 4 is sufficiently supplied el @ ktrisoli @ s Si to the desired evaporation rate erhaltoi zn ""

In a specific Ausführungtsbeispiel a source according to the invention for iie halbkontinuierliclie evaporation of aluminum a Gefäs® 1 of @ in @ m solid ■ block boron nitride was milled, the doors at the aufteetsaden T © Eafera = "substantially realstenfc against V / ungsten and gesohmolzenes Aluminum isto the Sefäsa had © in © length of 41 ^ffi ^ (1 5/8 inch) a width of 14 ram (9 / I6 inch) tmd eis © Ti @ f © of 17i5 mm (1 I / 16 ZoIl) _{0 der} Cavity 2 was in the middle of the load

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. Top 6 and was approximately 35 mm (1 3/8 ") long, 11 mm (7/6") wide, and 3 mm (1/8 ") deep. Compartment 3 was formed by drilling a 11 mm (7/16 inch) diameter hole lengthways through the lower part of the vessel, the wall thickness on the underside of the vessel being 1.6 mm (1/16 inch). The "underside of the vessel was rounded so that the wall thickness around the entire lower half of the compartment was about 1.6 mm (1/16 inch) throughout."

The heater 4 consisted of 1Θ interleaved tungsten filaments made by placing a 1 mm (0.040 inch) diameter tungsten wire on a 1.5 mm (0.060 inch) diameter core with a pitch of about 2 1/2 After removing the core, each coil was trimmed to a length of 100 mm (4 inches). 17 Sjulen were then each IRER boxes ", a mat to b: .lden that Wurd then brought diameter to a cylindrical pin of 3.2 mm (l / n _inch); and the eighteenth thread was threaded through the first and second long spirals to form a cylindrical net 100 mm (4 inches) in length with an outer diameter of about 10 mm (15/32 inch) after removal from the tenon a tungsten rod 5 ron about 3.2 mm (1/8 inch) in diameter and 25 mm (1 inch) in length

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inserted each end of the heater 4 and the ends of the heater 4 were heliare-welded to make the rods and coils with connect each other su. The tungsten rod 5 can also be provided with items.

The heater 4 was then placed in compartment 3 of vessel 1 so that about 30 mm (1 3/16 inches) protruded from each end of vessel 1. The evaporative element was then mounted in a vacuum deposition chamber and about 25 mm (1 inch) each The end of the heater 4 was clamped with water-cooled, copper, semi-rigid retaining posts. Within the vacuum chamber was check means could supplied with the continuous aluminum wire the cavity 2 "ground _o The Druok in the chamber was au: f less than 0.001 Torr reduced", and to the support posts alternating voltage was applied. In the steady state there were 6 volts on the heater and ^ s about 500 amps flow through this

ο The temperature of the vessel was about 1300 ° C

1400 C, and the aluminum was at a rate of 4 g per

Now evaporates.

During start-up, at dom the delivery rate of the aluminum is adapted to the evaporation rate, the cavity 2

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flood »if a lot of aluminum is delivered» if that can be overflowed with the heater in Touch come »and corrode it.

In the case of the embodiment according to FIG. 4, therefore, between the respective ends of the cavity 2 and the vessel 1 channels θ arranged, which generally across the longitudinal dimension of the vessel 1 rQiohen, but a distance from the cavity 2 and the End of the vessel lake 1. There are at least eight channels overflowing the entire surface 6, but the sides of the vessel can also be rowed over. Until the width and depth of the channels are 8 usually small compared to the size of vessel 1 and theirs The task consists in »liquid netall, which over the cavity flows away from the heater 4, the cross-sectional area of the Channel 8, however, must not be so small "so that the surfaces" tension of the liquid metal "it prevents it" under the influence of gravity in the channels 8 -rom the heater 4 to flow away When the liquid metal floods the cavity 2, the conduct Channels 8 it from outside down to the bottom of the vessel 1, where it drains harmlessly »generally on an umbrella on the ground the precipitation chamber

In the embodiment of Fig. 4, the structure is the same as explained in connection with Fig. 1, in a special execution

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However, other vessels were used. The vessel had a length of 54 mm (2 tons / 8 inches), a width of 14 mm (9/16 in.) And a depth of 27 mm (1/16 in.). Of the Cavity 2 was arranged centrally in the top 6 and approximately 35 mm (1 3/8 in.) Long, 11 mm (1/6 in.) Wide, and 3 »2 mm

(1/8 inch) deep. Sas compartment 3 was set up in the same way as that at φ

the embodiment of FIG. 1o to channels 8 were 3 ₈ 2 '(1/8 inch) mm from each end of Gefäsees 1 round milled and had a depth and width of 3.2 mm (t / β Zoil) ₀ They formed a effective barrier between cavity 2 and heater 4 - In consideration of the greater length, the length of the heater and the individual heating coils were each 115 mm (4 1/2 inches). -

In another Aueführungeform of the invention according to Figo 5

and 6 is the barrier between cavity 2 and hoarse 4 ^

an elongated · hitζresistant sleeve 9. The sleeve 9 is around the

Heater 4 arranged around and prevents direct contact

between the heater 4 and the vessel 1 “This sleeve 9 existed in the illustrated embodiment made of boron nitride and had an inside diameter of 11 mm (7/16 inch) and a wall thickness 0.8 mm (1/32 inch). Then compartment 3 has a diameter a little more than 13 mn 0/2 inches) and the diameter of the heater was just under 11 mm (7/16 in). When the hoarse 4 in the sleeve 9 was inserted, and both were inserted in compartment 3,

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each stood about 13mm (½ inch) of the sleeve 9 on the Ends of jar 1 protruded, and 25 mm (1 inch) heater 4 stood over the ends of the sleeve 9. With these protruding ends, the heater 4 can again be clamped onto the holding posts will. When liquid metal flows over the cavity 2 and the top 6, it can be applied to the ends of the vessel 1 protruding parts of the sleeve «9 f Hesse. To build a to prevent liquid metal on the sleeve 9, which could then flow over the ends onto the exposed ends of the heater 4, If the upper sides of the Htiltse 9 are beveled or curved, preferably convex · Sas Ketal !, then flows downwards and from the Sleeve 9 from, but not out at the ends.

In operation, the case is generally at a higher temperature « door than the vessel 1, because »it is closer to the heater 4 and also the metal is not cooled directly by the vaporiser ο the sleeve 9 can sometimes be hot enough to overflow a liquid Evaporate metal BU, same *; if the vessel 1 is not hot enough is to prevent flooding.

Another possible cause of having liquid metal with comes into contact with the heater 4, lies in the surface tension .. If the vessel 1 is slightly wetted by liquid metal, the metal can spread and onto the surface of the vessel 1

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krieoheno If, for example, the vessel 1 is made of graphite or

Boron nitride and the liquid metal aluminum at a

ο If the temperature is above about 1400 C, the liquid aluminum wets the surface of the vessel 1 and gradually spreads from the Cavity 2. In this case the invention prevents Block the flow of molten metal to the exposed one Heater by the length of the path between the heater ends and the hollow ridge 2 is significantly increased »

Instead of one continuous sleeve 9, two shorter ones can also be used Sleeves made of boron nitride are used, which protrude from the vessel 1 by approximately the same amount as the continuous sleeve, however, do not pull it completely through the compartment 3.

The vessels and sleeves described were made of boron nitride, however, other materials can also be used are resistant to aluminum and tungsten, for example

Aluminum nitride, 'fitankarbid, Zirkondiborld and *' itanborid, or any combination or mixture of these, if aluminum is to be precipitated from the steam, since all these substances are made up of sufficient corrosion resistance for the; purposes according to the invention »ind.

The oefks and sleeves can also be made by that the heat-resistant powder is called in a graphite matrix »

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is pressed »which is shaped accordingly» Or you can cold-press the heat-resistant powder or a paste of this powder into a suitable shape, which is followed by a high-temperature sintering process in order to obtain the required stability and strength Basic idea of the invention for vacuum deposition other metals, such as gold, silver, chromium, nickel and the like can be used if the heat-resistant material used is correctly selected with regard to the corrosion resistance against the heating element and the metal which evaporates from the "o the compounds mentioned are selected for example also suitable for vaporizing gold, silver and copper _{or the like}

A cylindrical net heater has also been described, other shapes such as polygonal shape, elliptical or semi-flat cross-sections can also be used. These shapes are produced by the fact that the mat of interwoven coils is applied to a suitably shaped pattern and attached, and the ends of the heating element fade to the original shape; are ₀ Bereioh In the invention also is that the other resistors Netzheizelement '"heating wires are made of high-melting metals ka ~ in, which have a melting point of over 2000 ⁰ G, such as molybdenum, tantalum or niobium.

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Claims (1)

4 * S6 P40 D Patentans ρ r Ü ο h β 1. Evaporation source for the deposition of metals in the Vacuum, consisting of a hoarse and a hitz @ be *> standing vessel with a cavity on the top » characterized in that the heater is a resistance » Heating element is »that consists of interleaved coils of wire made of high-resistance metal, whereby they Turns of the coils are held by the turns of adjacent coils, so that the individual turns freely can expand and contract, and the heat-resistant® vessel is elongated, supported by the heating element and can absorb heat from it. 2Q evaporation source according to claim 1, characterized _s that the wire is made of tungsten metal hoohsohmelzendem 3. Evaporation source naoh claim 1 or 2, characterized net that the depth of the cavity is »less than 1/5 of the depth : .η vessel · 4. Evaporation source according to claim 1, 2 or 5f characterized by g% /; cenn> » draws that the heater is cylindrical. ■ - A2 ~ 109885 / U50 -he" 5 »Evaporation source naoh one of claims 1 - 4i claöuron characterized} that the vessel has an elongated compartment in which the dex pickle is arranged and whose wersohnitt is preferably adapted to the cross section of the heater. 6 »Evaporation source naoh one of claims 1 -5, thereby characterized in that the ends of the heating element protrude beyond the ends of the vessel. Evaporation source nnoh one of claims 1-6, characterized marked that the vessel consists of boron nitride. 8. evaporation source according to any one of claims 1-7, characterized characterized in that a device is provided with which the metal to be vaporized is prevented from with the. To come into contact with the heater * <?. Evaporation source according to claim 8, characterized that the device consists of a lock between the cavity and the element consists = - A3 - 5/1450 bad original 10ο Tl evaporation source according to claim 9 »characterized in that the barrier consists of a recess in the vessel between the ends of the tube and the ends of the vessel, which extends at least over the top of the vessel and in the AbBba, nd of the foal nium is arranged _o ο TerdampfungequeliIe according to claim 9 or 1O _8, characterized in that the barrier consists of an elongated heat-resistant element which is arranged between the heater and the vessel, the ends of the element being arranged between the ends of the vessel and the heating element 109885 / U50