WO2017088842A1

WO2017088842A1 - Cylindrical cathode for deposition of layers by pvd method

Info

Publication number: WO2017088842A1
Application number: PCT/CZ2016/000125
Authority: WO
Inventors: Mojmir Jilek
Original assignee: Platit A.S.
Priority date: 2015-11-27
Filing date: 2016-11-22
Publication date: 2017-06-01
Also published as: CZ306541B6; CZ2015837A3

Abstract

A cylindrical cathode for deposition of layers by the PVD method, comprising a tubular central carrier (1) with a target (2) arranged on its circumference. The central carrier (1) is, at least in the area of the target (2), provided with a space (3) for flowing of pressure cooling liquid with an inlet (6) of cooling liquid and an outlet (7) of cooling liquid. A source (5) of magnetic field is arranged inside the central carrier (1). The space (3) for flowing of pressure cooling liquid is separated from the target (2) by an elastic tube (4) the outer diameter of which fits onto the inner diameter of target (2). The outer diameter of the central carrier (1) in the area under the target (2) in the idle state corresponds in principle to the inner diameter of the elastic tube (4). The space (3) for flowing of the pressure cooling liquid is formed by a system of through openings arranged in the jacket of the central carrier (1) in the area under the target (2).

Description

Cylindrical cathode for deposition of layers by PVD method Technical Field

5 The invention relates to a cylindrical cathode for deposition of layers by the PVD method, comprising a tubular central carrier with a target arranged on its circumference, wherein the central carrier is, at least in the area of the target, provided with a space for flowing of pressure cooling liquid with an inlet of cooling liquid and an outlet of cooling liquid, wherein a source of magnetic field is arranged o inside the central carrier, wherein the space for flowing of pressure cooling liquid is separated from the target by an elastic tube the outer diameter of which fits onto the inner diameter of the target.

Prior Art

.5

The method of physical deposition from gaseous phase, designated with abbreviation PVD (Physical Vapour Deposition), is a method of depositing thin layers.

:o The depositing of layers takes place in a vacuum chamber. Before the depositing of layers, pressure in the chamber is reduced, the chamber is heated up to particular temperature depending on the tool material, adhesive layer and wear- resistant layers are successively deposited.

!5 The cylindrical cathode for deposition of layers by the PVD method is placed inside the chamber and, during deposition, it rotates so that the deposited material would evaporate from the cathode uniformly.

The cylindrical cathode for deposition of layers by the PVD method includes the 10 tubular central carrier with the material to be deposited arranged on its circumference. This material is marked as target. The central carrier is, at least in the target area, provided with space for flowing of pressure cooling liquid with inlet of cooling liquid and outlet of cooling liquid. The source of magnetic field is arranged inside the central carrier.

In the case that the target is made of easily machinable materials, for example Ti, TiAI, Al, it is preferable to make the target directly in the tubular shape from a single piece that embraces coaxially the central carrier.

In the case the target is made of materials difficult to machine, for example T1B2 or B₄C, the target is made in the form of ring segments. To provide for good heat transfer these segments are soldered or glued next to each other on the central carrier. Such embodiment is known, for example, from document US2014174920A1.

Soldering of targets can be realized using a solder with low melting temperature or a solder with high melting temperature.

When the solder with low melting temperature (e.g. that based on In) is used the maximum power that can be brought to the cathode is limited by temperature at which the target is unglued (and subsequently destroyed). Higher power can be brought to the cathode when the solder with high melting temperature (so-called hard solder, preferably active solder with an admixture of Ti, or Si) is used. Nevertheless, cracks can develop in the target already during soldering of the target onto the central carrier, or during cooling after soldering. The reason is different thermal expansion of materials of the central carrier and target. For the same reason, destruction of the target can take place at thermal load during the deposition process when the material is repeatedly cooled and heated.

Both methods result in limited maximum power that can be brought to the cathode. In this way, total time of deposition of layers by the PVD method is extended.

The gluing method includes similar problems as the soldering method. On one hand, it is somewhat easier to glue the target than to solder it, nevertheless, gluing typically results in a worse thermal contact and, thus, even greater limitation of maximum power.

A method of cooling target via a thin copper sheet is known for planar targets. 5 Naturally, this known embodiment is not intended for compensation of thermal dilatation of the target during heating and cooling.

Document WO03080891 discloses a rotating tubular cathode for sputtering facilities in which, for example, window glass is coated. Said tubular cathode o normally has fluid cooling. In order to render the replacement of said cathode easier, a cylindrical, elastic foil is provided between the target located in the periphery of the tubular cathode or the target carrier arid the central longitudinal axis of said tubular cathode. Said foil seals off the fluid circuit from the target, thereby forming a closed system. Disadvantage of this embodiment is that the

5 magnets are in direct contact with the cooling liquid which causes corrosion especially when the most suitable magnets of FeNd-type are used. The magnets also collect magnetic materials from the cooling water. The corrosion and the collected magnetic materials decrease the strength of the magnetic field.

!0 Document US2014174920 discloses an evaporation source, in particular for use in a sputtering process or in a vacuum arc evaporation process, preferably a cathode vacuum arc evaporation process. The evaporation source includes an inner base body which is arranged in an outer carrier body and which is arranged with respect to the outer carrier body such that a cooling space in flow communication with an

»5 inlet and an outlet is formed between the base body and the carrier body. In accordance with the invention, the cooling space includes an inflow space and an outflow space, and the inflow space is in flow communication with the outflow Space via an overflow connection for the cooling of the evaporation source such that a cooling fluid can be conveyed from the inlet via the inflow space the so overflow connection and the outflow space to the outlet. Different thermal expansion of the outer carrier body and of the inner base body must be compensated by an expansion element in the form of a spiral spring. However only axial thermal dilatation is compensated. Heat transfer between the outer carrier body and the inner base body is therefor not fully compensated.

Disclosure of the Invention

5

Drawbacks of the state of the art are remedied by a cylindrical cathode for deposition of layers by the PVD method, comprising a tubular central carrier with a target arranged on its circumference. The central carrier is, at least in the area of the target, provided with a space for flowing of pressure cooling liquid with an inlet o of cooling liquid and an outlet of cooling liquid. A a source of magnetic field is arranged inside the central carrier. The space for flowing of pressure cooling liquid is separated from the target by an elastic tube the outer diameter of which fits onto the inner diameter of target. The outer diameter of the central carrier in the area under the target in the idle state corresponds in principle to the inner diameter of

5 the elastic tube and the space for flowing of the pressure cooling liquid is formed by a system of through openings arranged in the jacket of the central carrier in the area under the target. - ^{.. ' "}

An advantage of the solution according to the invention is optimum flow of !0 pressure cooling liquid and that the elastic tube perfectly copies t ermal dilatation of the target; hence, high power can be brought to the cathode without cracks being formed on it. Higher power then results in a shorter time of deposition of the coating. The technology of producing such cylindrical cathode is cheaper than known soldering or gluing technologies and, moreover, the central carrier can be !5 used repeatedly. ^{^} · -

According to another preferred embodiment, the elastic tube is made of copper. The target can be built up of several follow-up ring segments arranged in tandem. According to the preferred embodiment, the space for flowing of pressure cooling liquid is formed by reducing outer diameter of the central carrier in the area under the target, wherein the elastic tube fits onto the central carrier just in places of 5 connection on both ends of the target.

According to the preferred embodiment, the source of magnetic field is separated from the flow of the cooling liquid by a housing. o Brief Description of Drawings

The cylindrical cathode according to the invention is described in details on two examples of particular embodiment that differ in design of the central carrier with the target. The first example of embodiment of the cylindrical cathode is depicted 5 in Fig. 1. Fig. 2 shows the central carrier with the target and Fig. 3 just the central carrier of the cylindrical cathode from Fig. 1. The second embodiment of the central carrier with the target is depicted in Fig. 4 and the central carrier of this embodiment is depicted in Fig. 5.

:o Description of preferred embodiments

Fig. 1 shows schematic cross-section of the first example of embodiment of the cylindrical cathode for deposition of layers by the PVD method. The cathode includes a tubular central carrier 1 with a target 2 arranged on its circumference. :5 Fig. 2 shows just the central carrier 1 with the target 2 and Fig. 3 shows the central carrier 1 only.

The target 2 comprises follow-up ring segments made, for example, of TiB₂, B₄C, W, TiSi.

o

The central carrier 1 is, in the area under the target 2, provided with a space 3 for flowing of pressure cooling liquid with an inlet 6 of cooling liquid and an outlet 7 of cooling liquid. A source 5 of magnetic field is arranged inside central carrier 1 in a separated area (see Fig. 1) so that the source 5 of magnetic field is separated from the flow of the cooling liquid.

The space 3 for flowing of pressure cooling liquid is created by reducing outer 5 diameter of the central carrier 1 in the area under the target 2.

The space 3 for flowing of pressure cooling liquid is separated from the target 2 by an elastic tube 4 onto which the target 2 fits. o The elastic tube 4 fits onto the central carrier 1 just in places of connection 9 on both ends of the target 2 where the elastic tube 4 is glued or soldered to the central carrier 1.

A removable part 8 (see Fig. 1) enables the segments of the target 2 to be easily 5 replaced.

In the depicted example of embodiment, the elastic tube 4 is made of Cu and its wall thickness is 0.1 mm. For the reasons of simplicity of design, the elastic tube 4 is preferably made of an electrically and thermally conductive material, in particular o of metal or electrically conductive plastic, for example, of the electrically conductive plastic commercially available under the trademark TECACOMP TC. In the case that another supply of electric current to the target 2 is provided an elastic tube made of an electrically non-conductive material can also be used.

5 Wall thickness of the elastic tube 4 is selected within the range from 0.01 mm to 1 mm, preferably from 0.05 mm to 0.2 mm.

The ring segments of the target 2 are pushed onto the elastic tube 4 which is cooled on its inner side by the pressure cooling liquid. As the wall thickness of the o elastic tube 4 is 0.1 mm only and pressure of the cooling liquid is 0.2 MPa, the elastic tube 4 expands and perfect thermal and electric contact is created between the tube 4 and the segments of the target 2. In depositing thin layers, higher power can be brought to the cylindrical cathode made in this way than that in the case of known cathodes, because the elastic tube 4 copies perfectly thermal dilatation of the target 2 so that no cracks are formed on it. Higher power results in subsequent reducing of time of coat 5 depositing.

The central carrier 1 can be used for holding the targets 2 repeatedly.

According to the preferred embodiment, the elastic tube 4 can be made with o smaller outer diameter than the inner diameter of the target 2. After that a tubular jig of the same inner diameter as the inner diameter of the target 2 can be pushed onto the elastic tube 4 and the elastic tube 4 is .formated" by supplying water of pressure of 0.5 MPa. The elastic tube 4 is deformed and, after discharging the water, it has exactly the„correct" diameter.

5

Figs. 4 and 5 show another embodiment of the central carrier 1. The outer diameter of the central carrier 1 in the area under the target 2 in the idle state (i.e. without any cooling liquid) corresponds in principle to the inner diameter of the elastic tube 4. The space 3 for flowing of pressure cooling liquid is formed by a o system of through openings arranged in the jacket of the central carrier 1 in the area under the target 2.

The rest of the structure of the cylindrical cathode is the same as in the embodiment in Fig. 1. The ring segments of the target 2 are pushed onto the 5 elastic tube 4 which is, from its inner side, cooled by the pressure cooling liquid penetrating by the system of the through openings in the jacket of the central carrier 1. The pressure cooling liquid presses on the elastic tube 4 creating thus perfect thermal and electric contact between the tube 4 and the segments of the target 2.

o

List of reference marks

1 central carrier

2 target space for flowing of pressure cooling liquid elastic tube

source of magnetic field

inlet of cooling liquid

outlet of cooling liquid

removable part

connection

Claims

1. A cylindrical cathode for deposition of layers by the PVD method, comprising a tubular central carrier (1) with a target (2) arranged on its circumference, wherein

5 the central carrier (1) is, at least in the area of the target (2), provided with a space (3) for flowing of pressure cooling liquid with an inlet (6) of cooling liquid and an outlet (7) of cooling liquid, wherein a source (5) of magnetic field is arranged inside the central carrier (1), wherein the space (3) for flowing of pressure cooling liquid is separated from the target (2) by an elastic tube (4) the outer diameter of which o fits onto the inner diameter of target (2), characterized in that the outer diameter of the central carrier (1) in the area under the target (2) in the idle state corresponds in principle to the inner diameter of the elastic tube (4) and the space (3) for flowing of the pressure cooling liquid is formed by a system of through openings arranged in the jacket of the central carrier (1) in the area tinder the

5 target (2).

2. The cylindrical cathode according to Claim 1 , characterized in that the elastic tube (4) is made of an electrically conductive material, in particular of metal or electrically conductive plastic, and its wall thickness is within the range from 0.01

!0 mm to 1 mm, preferably from 0.05 mm to 0.2 mm.

3. The cylindrical cathode according to Claim 1 or 2, characterized in that the elastic tube (4) is made of copper.

:5 4. The cylindrical cathode according to Claim 1 , 2 or 3, characterized in that the target (2) is built up of several follow-up ring segments arranged in tandem.

5. The cylindrical cathode according to any of the Claims 1 to 4, characterized in that the source (5) of magnetic field is separated from the flow of the cooling liquid ;o by a housing.