DE102015117182A1 - Method and device for evaporating material - Google Patents

Abstract

The invention relates to a process for vaporizing material in which a certain amount of vaporization material is provided as bulk material, wherein the vaporization material is first conditioned and then vaporized, wherein only a subset of the provided amount of vaporization material is conditioned and then the conditioned subset is evaporated, and an apparatus for vaporizing material, comprising an evaporator crucible for receiving evaporating material, and an energy source for directing energy input into the evaporating material, wherein the evaporator crucible is arranged such that a surface of evaporating material provided on or in the evaporator crucible is inclined to the horizontal.

Description

The invention relates to methods and apparatus for evaporating material.

There are given methods and apparatus for vaporizing various materials in a vacuum, wherein the term "evaporation", depending on the material to be evaporated, and sublimation should be understood. For example, methods and devices for evaporating present as bulk evaporating material, such as oxides and oxide mixtures such as TiOx, SiOx, ZrO, NbOx, CrOx and metals and metal alloys are given.

In the thermal evaporation of coating material by means of local energy input (e.g., electron beam), there are various ways to realize long campaign durations. In addition to the storage of evaporation material in large evaporator crucibles, the Nachfütterung or tracking of material in a suitable form is possible. In many cases, it is necessary to keep the vapor source almost stationary with respect to a target area (also referred to as a coating window) to avoid variations in coating rate. Thus, it has proven useful to condition evaporation material in large vaporizer crucibles in a pre-process and then to remove the conditioned vaporizing material by suitable movements of an evaporator crucible. Disadvantage of this arrangement is the usually quite large volume of the evaporator crucible, which makes long conditioning times required, leads to a high thermal inertia and also leads to a strong thermal substrate load by the large, the substrate facing evaporation material surface. Alternatively, for materials that can be made in a defined rod shape, the reverse strand replenishment method can be used, with a rod inserted from below into the vaporizer crucible. For some materials, however, the production of suitable shaped pieces is so complicated that they are only available inexpensively as bulk or bulk material. You can feed the bulk material from above into the melt. However, splashes always occur, which makes it necessary to interrupt the coating test. It is also known that some materials can be evaporated at relatively low powers by being introduced as bulk material directly into a horizontal, rotating, water-cooled copper crucible, which is channel-shaped, and completely vaporized by electron beam. In this case, the electron beam must act on the evaporator crucible directly, which limits the maximum possible energy input significantly.

The aim of the invention is to improve the known state of the art and to propose methods and devices in which bulk material is supplied to the evaporation process so that a stable, continuous evaporation over long periods of high rates is possible and on the one hand large amounts of vaporization material to be heated be avoided and on the other hand, an interruption of the evaporation process for conditioning is no longer necessary.

For this purpose, a method for evaporating material is first proposed, in which a certain amount of evaporation material is provided as bulk material, wherein the evaporation material is first conditioned in a connected process and then evaporated, wherein only a subset of the provided amount of evaporation material to the process from a storage vessel is supplied and conditioned and then the conditioned subset is evaporated.

In contrast to known solutions in which always the entire amount of, for example, provided in an evaporation crucible evaporation material is conditioned, although at any time only a relatively small proportion is currently evaporated, therefore, in the proposed solution always only a small subset of the provided evaporation material is conditioned , The total amount of energy contained in the provided evaporating material and possibly having an adverse effect on the overall process is thereby significantly lower than in known processes. A significant advantage is the time savings that can be achieved because the conditioning can take place simultaneously with the evaporation. The most time-consuming conditioning of the entire vaporization before evaporation can be omitted.

According to various embodiments of the proposed method, it can be provided that the conditioned subset of the provided evaporation material represents only a fraction of the total amount of evaporation material provided, the fraction being less than half, more preferably less than a quarter, more preferably less than one tenth, more preferably less than one-hundredth of the amount of evaporation material provided. In this case, the lower the subset of conditioned vaporization material relative to the amount of vaporization material provided, the more effective the method, and the less detrimental the results of the process.

According to various embodiments of the proposed method can be provided that a distance between a Place of evaporation and a place of precipitation, ie the place where, for example, a substrate to be vaporized is located or at which it is moved, for example, in a substrate transport plane, is kept constant. As a result, on the one hand particularly homogeneous coating results are achieved. Changes and drifts in the coating result due to distance-dependent process variables (eg coating rate, impact area of the energy source) can be avoided. On the other hand, the adverse effects of secondary effects (eg, thermal stress on the substrate, secondary electrons), which may emanate from the conditioned portion of the evaporation material provided on substrates to be treated, are both constant and minimized.

According to various embodiments of the proposed method it can be provided that evaporation material is provided in an evaporator crucible, a local energy input into a partial surface of the evaporation material takes place at a fixed evaporation location and the evaporator crucible is moved so that during the movement continuously new evaporation material is conditioned and subsequently the conditioned evaporation material is evaporated.

This means that, on the one hand, the energy source, for example an electron beam gun, can be permanently installed and no further means for large-scale movement of the impact of the electron beam are needed, and on the other hand, that always only the next required for the evaporation subset of evaporation material must be conditioned can then be evaporated directly. Not least because of this, the process can be carried out very energy efficient.

According to various embodiments of the proposed method it can be provided that evaporation material is provided in an evaporator crucible, wherein the evaporator crucible is moved in a direction inclined relative to the horizontal or / and rotated about an axis inclined relative to the vertical. In particular, in the case of a translatory movement of the evaporation crucible in a direction inclined with respect to the horizontal, it can further be provided that the evaporation material is vaporized at an evaporation location which is arranged at the highest point of the evaporation material arranged on the evaporator crucible. In an example, annular evaporator crucible, which is rotated about an axis inclined relative to the vertical, the evaporation can be carried out for example between the highest and the lowest point of the crucible surface. In this case, evaporating material usually remains in the crucible after passing through the evaporation location. This evaporation material reaches only after another rotation, for example, by about 90 °, the highest point of the crucible rotation.

This makes it possible that both the conditioning and the evaporation can take place on the one hand at a fixed location and on the other hand, the energy input into the evaporation material from its surface facing the energy source extends very far into the depth. This measure also contributes significantly to the fact that the proposed method is extremely energy efficient. In addition, a larger cross-sectional area of the supplied material is achieved than with horizontal feed. According to various embodiments of the proposed method it can be provided that evaporation material is supplied to a vaporization site by movement of an evaporator crucible containing evaporation material and / or by a velocity of movement of an evaporator crucible containing vaporization material such that vaporized vaporization material is discharged predominantly in a predeterminable evaporation direction.

By this measure, it is possible to specifically influence the direction in which the vaporized portions of the evaporation material are discharged from the evaporator crucible. In other words, it is thereby possible to produce, for example, a substantially vertically upward steam jet. This is particularly useful when, for example, plate-like substrates are or are placed in a horizontal position in the region of the device or are passed by the device hit by the generated vapor jet, whereby the vapor particles deposit on the surface of the substrate and thus a thin surface coating form on the substrates. It is also possible, for example, to generate a substantially horizontally directed steam jet. This is particularly useful when, for example, plate-shaped substrates are or are placed in a vertical position in the region of the device or past the device encountered by the generated vapor jet, the vapor particles depositing on the surface of the substrate and thus a thin surface coating form on the substrates.

According to various embodiments of the proposed method, it can be provided that evaporation material is provided in or on an evaporator crucible and that refilling material is replenished at a refilling location arranged away from an evaporation location.

This makes it possible to make the process uninterrupted for long periods of time. Replenishing evaporating material at a refilling location remote from the evaporation site also eliminates the negative effects that may otherwise result when fresh evaporating material is added to already conditioned material.

Furthermore, a device for vaporizing material is proposed, which comprises an evaporator crucible for receiving evaporating material and an energy source for directing energy input into the evaporating material, wherein the evaporator crucible is arranged so that a surface of evaporating material provided on or in the evaporator crucible is inclined with respect to the horizontal is.

This proposed device makes it possible that both the conditioning and the evaporation can take place on the one hand at a fixed location and on the other hand the energy input into the evaporation material from its surface facing the energy source extends very far into the depth. This measure contributes significantly to the fact that the proposed device is extremely energy efficient.

According to various embodiments of the proposed device can be provided that the evaporator crucible is movable relative to the power source. For example, it may be provided that the evaporator crucible is movable in a direction inclined relative to the horizontal and / or about an axis inclined relative to the vertical axis.

Furthermore, according to various embodiments of the proposed device, it may be provided that the energy source is designed to generate a local energy input into a partial surface of the evaporation material at a fixed evaporation location.

As a result, on the one hand the energy source, such as an electron gun, be permanently installed and other means for large-scale movement of the impact of the electron beam are not needed. On the other hand, it is always necessary to condition the only subset of evaporation material needed for the evaporation, which can then be evaporated directly. This also works the proposed device very energy efficient.

According to various embodiments of the proposed device it can be provided that a refilling device for refilling evaporation material is arranged at a refilling location arranged away from an evaporation location. This makes it possible to achieve a very long campaign duration without having to interrupt the process. For example, a refilling device can be arranged at the refilling location, with which evaporation material can be refilled continuously or discontinuously as required into the evaporator crucible.

The proposed methods and apparatus will be explained in more detail with reference to drawing figures. Show

1 a device according to a first embodiment,

2 a device according to a second embodiment,

3 an evaporation zone in an example by the action of an electron beam statically generated evaporation, and

4 an evaporation zone in an example by the action of an electron beam dynamically generated evaporation site.

An evaporator crucible 2 for the supply of evaporation material 4 from below, for example, an advantageously water-cooled gutter 3 include, which is moved obliquely upward, as in the embodiment according to 1 shown. The shape of this groove 3 is advantageously designed to have a circular, molten or conditioned area 5 completely bounded on the side.

This groove 3 can also have a self-contained shape, which is arranged obliquely in space, so that in the region of evaporation, the supply of the evaporation material 4 done obliquely from below. 2 shows a round, rotatable vaporizer crucible with these features. For this purpose, the axis of rotation of the evaporator crucible 2 Tipped over the vertical. In the chosen representation, this is the lowest point of the channel 3 facing the viewer. The evaporation place 6 is higher in contrast.

In this embodiment, the apparatus comprises an inclined rotating annular trough evaporator crucible system having an axis of rotation which permits rotational movement in the plane of the annular form. The material supply is advantageously carried out at the lowest position 7 of the ring. The position of the steam source 6 can advantageously be done at half the height of the obliquely arranged ring.

The amount of material supplied results from the feed and the amount of evaporation material stored per length 4 , Advantageously, the device has a system for detecting the position of the melt lake or the conditioned area 5 and a control loop that controls the feed rate.

As in 3 shown, the bulk material is usually applied during the ring pass on an already molten and re-solidified area. The loaded area is then moved in the direction of the location of the energy input.

By the conditioned area or melting lake forming around the place of the energy input 5 the bulk material is absorbed or melted before it reaches the point of direct energy input.

In a particular embodiment, the evaporator crucible is at least partially covered by an aperture which may be tempered and only the area 6 from which is evaporated is open to the coating window. This avoids that splashes that could occur during melting, get to the substrate. In addition, the radiation from the hot evaporation material 4 reduced to the coating window.

In a further embodiment, in 4 is represented by the energy source 1 acted upon area designed so that forms a particularly shaped melting lake or conditioned area for receiving the bulk material lying on the ingot without hitting the bulk material directly. In other words, in addition to the energy input for shaping the steam source area 6 Another energy input for special shaping of the melt lake or the conditioned area 5 in the evaporation material. In the specific embodiment, the conditioned area 5 next to the out 3 known simple circular shape, resulting in stationary energy input, two extending from the central region of wings, by appropriate steering of the electron beam 1 form. In the area of action of these wings is the evaporation material 4 immediately before the evaporation site on a narrow area 5 conditioned.

A device for supplying bulk or bulk material according to one embodiment comprises a water-cooled rotating evaporator crucible 2 with a usually preconditioned ingot and is equipped with a refill, the piece or bulk material in a defined amount at the sheltered from evaporation point in the evaporator crucible 3 refills.

Advantageously, the replenishment amount is metered according to the evaporated volume and the feed rate, which can be done via a control loop.

The feed with evaporation material 4 can be done either from a reservoir from above, horizontally or obliquely from below, with a suitable means (eg vibrator, cross-sectional limitation, screw conveyor) a filling with a defined cross section and defined bulk density in the evaporator crucible 2 is introduced.

In a particular embodiment, the evaporator crucible is fed by a plurality of evaporation and refill devices. This also makes it possible, for example, to supply two or more different materials by defined or defined adjustable cross sections in certain proportions.

The evaporation takes place from a superheated evaporation area or steam source area 6 as part of the molten or conditioned area 5 of the evaporation material 4 , By moving the evaporator crucible 2 at the same time stationary position of the energy input 1 for generating the superheated steam source area 6 shifts the melted or conditioned area 5 along a path relative to the evaporator crucible 2 , In the process, the evaporation material positioned on this web as bulk material becomes 4 from the edge of the melt or the conditioned area 5 reached and from the melt or the conditioned area 5 added. Advantageously, it does not get into the directly through the energy source 1 acted upon steam source area 6 before it is melted or conditioned, thereby avoiding spraying in the steam source area.

• 1. Es wird ein Verdampfungsprozess gestaltet, bei dem nur eine begrenzte Materialmenge in einer konditionierten Verdampfungsumgebung gehalten wird, wodurch die thermische Belastung zu beschichtender Substrate und der Prozessumgebung begrenzt wird.
• 2. Der Bedampfungsabstand bleibt während der gesamten Kampagne konstant. Der Dampfquellbereich bleibt ortsfest, die Abdampfverhältnisse bleiben nahezu unverändert über lange Zeiträume während eines Beschichtungszyklus.
• 3. Durch die Schrägstellung des Verdampfertiegels oder der tiegelähnlichen Einrichtung wird ein tieferer Abtrag des Verdampfungsmaterials erreicht, wodurch der Bewegungsvorgang zur Materialfütterung in den Verdampfungsbereich gegenüber horizontal angeordneten Systemen entsprechend langsamer erfolgen kann und wodurch eine Standzeiterhöhung des Prozesses erreicht wird
• 4. Im Gegensatz zur seitlichen Materialzufuhr wird durch die schräge Zuführung von unten einer Schrägstellung der Dampfausbreitungsrichtung entgegengewirkt, insbesondere, wenn es sich um schwer bzw. zäh schmelzendes Verdampfungsmaterial handelt. Mit Hilfe der Vorschubgeschwindigkeit, die dann das lokale Abtragsprofil bestimmt, lässt sich die Orientierung der dampfabgebenden Fläche und damit die Richtung der Dampfausbreitung so beeinflussen, dass die Dampfabgabe z.B. vorwiegend senkrecht erfolgt. Es ist damit alternativ auch möglich, eine maximale Schrägstellung der Dampfausbreitung zu erreichen, um beispielsweise ein vertikal geführtes Substrat zu beschichten.
• 5. Die Materialzuführung kann räumlich getrennt vom Dampfquellbereich erfolgen.
• 6. Schließlich kann eine kontinuierliche Materialzuführung räumlich unterhalb des dampfabgebenden Dampfquellbereichs angeordnet sein, womit verhindert wird, dass die Funktionalität der Nachfülleinrichtung während eines vorgesehenen Verdampfungszyklus durch Streudampfablagerungen von der Dampfquelle beeinträchtigt wird.

The supply of the evaporation material 4 takes place advantageously obliquely from below, by an evaporator crucible 2 or a crucible-like device performs a movement component upward, wherein the molten or conditioned area 5 at least partially located on the bulk material. The Nachfütterung can first through in the evaporator crucible 2 stored evaporation material 4 and optionally further by continuously fed evaporation material 4 respectively. The following advantages are achieved for the evaporation process:

• 1. An evaporation process is devised wherein only a limited amount of material is maintained in a conditioned evaporation environment, thereby limiting thermal stress on substrates to be coated and the process environment.
• 2. The evaporation distance remains constant throughout the campaign. The steam source area remains stationary, the Abdampfverhältnisse remain almost unchanged over long periods during a coating cycle.
• 3. Due to the inclination of the evaporator crucible or the crucible-like device a deeper removal of the evaporation material is achieved, whereby the movement process for material feeding into the evaporation region with respect to horizontally arranged systems can be done correspondingly slower and thereby increasing the service life of the process is achieved
• 4. In contrast to the lateral supply of material is counteracted by the oblique feed from below an inclination of the steam propagation direction, especially when it is difficult or tough melting evaporating material. With the aid of the feed rate, which then determines the local removal profile, the orientation of the vapor-emitting surface and thus the direction of the vapor propagation can be influenced such that the steam is released, for example, predominantly vertically. It is thus alternatively possible to achieve a maximum inclination of the steam propagation, for example, to coat a vertically guided substrate.
• 5. The material supply can be spatially separated from the steam source area.
• 6. Finally, a continuous material supply may be located spatially below the vapor donating steam source region, thus preventing the functionality of the refill device from being affected by stray vapor deposits from the vapor source during a designated vaporization cycle.

LIST OF REFERENCE NUMBERS

1

Energy source, e.g. electron beam

2

vaporizing crucible

3

gutter

4

Evaporation material

5

conditioned evaporation material

6

Verdampfungsort

7

filling site

Claims (13)

Method for vaporizing material in which a certain amount of evaporation material ( 4 ) is provided as bulk material, wherein the evaporation material ( 4 ) is first conditioned in a connected process and then evaporated, whereby only a subset of the provided amount of evaporation material ( 4 ) is supplied to the process from a storage vessel and conditioned and then the conditioned subset is evaporated. The method of claim 1 wherein the subset represents only a fraction of the amount provided, the fraction being less than half, more preferably less than one quarter, more preferably less than one tenth, even more preferably less than one hundredth of the amount provided. Method according to Claim 1 or 2, in which a distance between a point of evaporation ( 6 ) and a precipitation site is kept constant. Method according to one of claims 1 to 3, wherein the evaporation material in an evaporator crucible ( 2 ) at a fixed evaporation site ( 6 ) a local energy input into a partial surface of the evaporation material ( 4 ) and the evaporator crucible ( 2 ) is moved so that during the movement continuously new evaporation material ( 4 ) and then the conditioned evaporation material ( 5 ) is evaporated. Method according to one of claims 1 to 4, wherein the evaporation material ( 4 ) in an evaporator crucible ( 2 ), wherein the evaporator crucible ( 2 ) is moved in a direction inclined relative to the horizontal or / and is rotated about an axis inclined relative to the vertical. Method according to one of claims 1 to 5, wherein the evaporation material ( 4 ) at a point of evaporation ( 6 ) vaporized at the highest point of the evaporator crucible ( 2 ) arranged evaporation material ( 4 ) is arranged. Method according to one of claims 1 to 6, wherein the evaporation material ( 4 ) by a movement of an evaporation material ( 4 ) containing evaporator crucible ( 2 ) and / or by a speed of movement of an evaporation material ( 4 ) containing evaporator crucible ( 2 ) an evaporation site ( 6 ) is supplied so that vaporized evaporation material ( 4 ) is discharged predominantly in a predeterminable evaporation direction. Method according to one of claims 1 to 7, wherein the evaporation material ( 4 ) in or on an evaporator crucible ( 2 ) and at a remote location ( 6 ) arranged refilling point ( 7 ) Evaporation material ( 4 ) is refilled. Device for vaporizing material, comprising an evaporator crucible ( 2 ) for receiving evaporation material ( 4 ) as well as one Energy source ( 1 ) for directed energy input into the evaporation material ( 4 ), wherein the evaporator crucible ( 2 ) is arranged so that a surface of or on the evaporator crucible ( 2 ) provided evaporation material ( 4 ) is inclined relative to the horizontal. Apparatus according to claim 9, wherein the evaporator crucible ( 2 ) relative to the energy source ( 1 ) is movable. Apparatus according to claim 9 or 10, wherein the evaporator crucible ( 2 ) is movable in a direction inclined relative to the horizontal and / or is rotatable about an axis inclined relative to the vertical. Device according to one of claims 9 to 11, wherein the energy source ( 1 ) for generating a local energy input into a partial surface of the evaporation material ( 4 ) at a fixed evaporation site ( 6 ) is trained. Device according to one of claims 9 to 12, wherein at a distance from a point of evaporation ( 6 ) arranged refilling point ( 7 ) a refilling device for refilling evaporation material ( 4 ) is arranged.

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