DE19947932C1 - Device for magnetron sputtering - Google Patents

Abstract

Device has an outer plasma electrode (9) with a first potential arranged between a target (1) and a counter electrode (10) with a second potential. An inner plasma electrode (8) with a third potential is arranged in the center of the target within the target region limited by the erosion zone. A screening electrode (11) with a forth potential open to the substrate is arranged on a vacuum flange (6) and surrounds the target, counter electrode, outer plasma electrode and inner plasma electrode. A number of gas outlet openings (12,13) are located on the inner plasma electrode and/or the outer plasma electrode. Plasma screens are located on the inner and/or the outer plasma electrodes to cover the gaps (34,35) to the target.

Description

The invention relates to a device for magnetronzer dust that essentially on a vacuum flange is arranged, the vacuum-tight in the chamber wall Vacuum chamber can be arranged. Inside the vacuum There are at least one chamber on the vacuum flange target connected to a cooling plate in a heat-conducting manner and a counter electrode. Be outside the vacuum chamber itself to create a tunnel-shaped, through the target urgent magnetic field at least one magnet system and a power supply unit with which the target and the Counter electrode via current feedthroughs in the vacuum flange are electrically connected.

Preferably belonging to the magnet system in a vacuum flange in the area of the poles of the ferromagne magnet system table pole shoes must be vacuum-sealed.

The device for magnetron sputtering can be combined in one wide procedural scope for separation thin layers of metals, alloys or chemical Compounds on substrates can be used to advantageous mechanical, optical or electrical properties to produce layers on substrates or such To improve properties.

Devices for magnetron sputtering, also called magne for short Called trons, there are many of them according to the state of the art known execution. The individual versions are mainly adapted to the specific tasks. A large number of magnetrons are designed that they can be used in any vacuum system that can. There are also known facilities operating in the Wall of the vacuum system can be installed.  

EP 0 095 211 A2 describes a magnetron in which one circular flat cathode in the wall of a plasma chamber is arranged. One substrate is the one to be atomized Surface opposite the cathode and an annular anode is coaxial to the axis between the cathode and the Substrate. To influence a magnetic field over the The device has a central rod-shaped cathode Electrode and at least one outer cylindrical electrode on, which are arranged isolated from the cathode and can be applied to variable potentials. At the end of central rod-shaped electrode can be a radially enlarged te disc be arranged with which the electric field is additionally influenced.  

DE 41 27 260 C1 describes a magnetron sputter source le for high vacuum and ultra high vacuum systems layering of large round substrates. The magnetron sputter source consists of a cooled target, an anode and a magnet system. The target is on a cooling plate and this insulated arranged on a base plate, wherein the cooling water insulates through the base plate is directed. The anode surrounds the target and is flat if attached to the base plate. The base plate closes an opening in the vacuum system in a vacuum-tight manner, and the magnet system is on the bottom of the atmosphere plate attached. In one embodiment of the invention the first cooling plate with the target concentric of one surround the second cooling plate with a second target. The The system is operated on the vacuum side by a plasma screen as an anode enclosed. For better penetration of the atmosphere side arranged magnet system through the base plate can in of these pole pieces.

The operation of such a facility takes place in be known according to the unipolar principle, in which the Target or the targets is at cathodic potential or lie and a separate one for the plasma discharge Anode is present.

Such a device is particularly reactive Atomizing for the deposition of insulating connections layers can only be used to a very limited extent because of the anode after a short period of operation with insulating layers is covered and loses its function. To the extent that grounded anode other parts of the vacuum chamber the function important to take over the anode Operating parameters of the magnetron sputtering device such as impedance, plasma expansion and coating rate, so that the quality of the deposited layers is strong Is subject to fluctuations. In the case of isolation of the  The device loses the anode from ground potential mentioned application after a short operating time fully functional.

DE 37 38 845 A1 gives a sputtering cathode after Magnetron principle, which is especially for the reactive Ab separation of insulating layers is proposed. she is by an additional center electrode in the area of non-eroding parts of the target and by an intermediate between a dark room shield and marked the target. Through these measures the Risk of arc discharge forming theirs Origin in the charge of insulating layers on the who have non-eroding target areas the. Long-term stable operation with reactive atomization is however not guaranteed with this facility because the dark room shield acting as an anode through coating becomes ineffective and parts of the vacuum came mer the anode function with the disadvantages described have to take over. The technical design of two ab screen housing, which are located at a short distance from each other and are exposed to the dense plasma is also problematic. Another disadvantage is that the plasma fills the entire vacuum chamber and with increasing Operating time too difficult to control potential shift exercises can lead.

DE 42 23 505 C1 describes a device for application poorly conductive or insulating layers indicated by reactive magnetron sputtering. Here is the Anode isolated outside a plasma screen, which limits the plasma. All parts with the plasma in Come into contact, except the target, are single or arranged together isolated from the anode potential net. However, the proposed facility has just changed if not for long-term stable coating  Atomization proven. It gets a heap of training from Arc discharges not only observed at the eroding target areas, but also on the sides surfaces of the target occur. Further serious deficits te of this facility refer to the local Uniformity of the degree of reaction, which in the nature of proposed gas inlets for the reactive gas directly in the plasma room originated.

The invention has for its object a device for magnetron sputtering of the type described in the introduction specify. In particular, the facility is intended to be a long one time-stable reactive deposition of thinner insulating Layers on substrates with relatively little technical Enable effort. It should be possible that the Furnishing in a universal way for different Plasma treatment and plasma coating processes can be used. The facility is intended for medium fre quent pulsed energy supply in both unipolar and also in bipolar mode of operation of the associated Stromver care facility applicable.

The invention solves the problem by characterizing the part of claim 1 mentioned features. Beneficial Further developments of the invention are in the subclaims are identified and are listed below together with the Description of the preferred embodiment of the invention, including the drawing, shown in more detail.

The essence of the invention is that between the Target and a counter electrode an outer plasma electrode trode, an inner plasma electrode in the center of the target and delimiting the plasma space towards the substrate open and the target, the counter electrode, the outer Enclose the plasma electrode and the inner plasma electrode eats, shield electrode are present. The  outer plasma electrode to a first optional potential, the counter electrode to a second one, the inner plasma electrode trode on a third and the shield electrode on a four optional potential. What electrode Which concrete potential is attached to is from the desired procedure depending. You can several or all electrodes also at the same potential be placed.

Furthermore, on the inner plasma electrode and / or the outer plasma electrode plasma shutters are present the respective column to the target at least partially cover, as well as on the inner plasma electrode and / or the outer plasma electrode gas outlet openings with at least one gas supply device are connected.

The concrete definition of the optional potential for the inventive plasma electrodes, the counter electrode and the shield electrode is made according to process engineering Viewpoints and depends in particular on Art of the target material, the process gas and the in the Magnetron device fed power.

In the simplest case, isolation is the one mentioned Sufficient electrodes, so that one moves freely real, so-called floating potential according to Plasma conditions. Preferably, the elec tread with adjustable voltage sources or according to claim 7 with a suitably sized network from resistors, capacitors and inductors for Setting the optimal potentials connected.

The proposed gas supply device causes one indirect homogeneous distributed supply of the working gas and of the reactive gas in the space of the highest plasma density.  

The invention has a particularly advantageous low Tendency to form arc discharges. Also at Use of the device according to the invention for deposition of layers with critical pairings of target material and reactive gas, e.g. B. with aluminum oxygen or silicon um-oxygen, have been over long process times significant arc discharges registered.

The apertures according to the invention between the inner plasma electrode and / or the outer plasma electrode and the Target prevent penetration of the plasma with high Plasma density in the gap areas where there is a high electrical and magnetic field strength is effective. The Gap coverage can be partial or complete. In an advantageous embodiment of the invention these screens are designed so that they are the same cover those target areas in which no erosion, but back dusting.

In the appropriate design according to claim 2 is Counter electrode in the space between the outer plasma electrode trode and the shield electrode arranged so that the optical line between the counter electrode and the target is interrupted by the outer plasma electrode. For Formation of the plasma discharge between the target and the In practice, counter electrodes are preferred as 5 to 30 mm between the outer plasma electrode and the shield electrode is provided. So the rooms are the actual plasma discharge, d. H. the space around the target inside the outer plasma electrode and the space around the Counter electrode connected together. The counter electrode is therefore almost completely against an undesirable loading layering protected. One through the invention Arrangement of low-performing secondary discharge in the The area of the counter electrode promotes the stability of the Magnetron discharge. For this embodiment of the invention  the power supply is typically operated unipolar ben.

In the embodiment of the invention according to claim 3 as a counter electrode with at least one other target an associated cooling plate used. This further Target can work in a similar way to the real one Target be formed. This creates one Double magnetron arrangement in which both targets are independent gig operated from each other unipolar or together bipolar can be. In any case, one of the targets is the Counter electrode during the sputtering phase of the other Targets. To do this, the power supply device must also known means the necessary energy feed into the Secure the magnetron discharge.

In a further advantageous embodiment of the Erfin extension according to claim 4 is a light sensor outside the Vacuum chamber arranged with a Lichtleiteinrich device that penetrates the vacuum flange and whose light entry opening is within the shade elec trode essentially perpendicular to a line between the surface of the target and the substrate. The Light guiding device can by fiber optic components be formed. Alternatively, a pipe is also suitable whose inner surface is designed to reflect light, or a mirror to deflect the light beam. With this sensor and possibly electronic signal processing units that are also conveniently on the vacuum flange are arranged outside the vacuum, lets the reactive atomization process is optimally regulated.

As a further embodiment, belonging to the magnet system of the target a mechanically adjustable lifting system au be present on the vacuum flange outside the vacuum chamber, which is the best possible adjustment of the magnetic field strength  on the target surface in the area of the magnetic Tunnels depending on the type of target material, the process conditions and the erosion state of the target enables.

With the device according to claim 6, in the vacuum flange a pressure sensor outside the vacuum chamber is arranged, which is enclosed by the shield electrode whose space is connected is a pressure measurement in possible in the immediate vicinity of the plasma discharge. There through a much better pressure measurement is achieved than that usually performed in the vacuum chamber ten pressure measurement, which is very beneficial when printing regulation in the plasma room and thus for the stability of the Magnetron discharge affects.

The device according to the invention is particularly universal optionally for the various known as such Process variants for magnetron sputtering can be used.

The invention is illustrated below in two embodiments play explained in more detail.

The associated drawing schematically shows the device according to the invention according to embodiment I in FIG. 1. FIG. 2 shows the device according to embodiment II.

Embodiment I

Fig. 1 is a schematic sectional view showing belonging to the exemplary embodiment I of an elongate rectangular device for magnetron sputtering. A cooling plate 2 made of copper with a target 1 made of aluminum, a counter electrode 10 and an outer plasma electrode 9 are arranged on a vacuum flange 6 , insulated on the vacuum side.

The target 1 is thermally and electrically conductively connected to the cooling plate 2 by means of a bonding layer. The cooling plate 2 and the target 1 are the same size and quite angular. The longitudinal dimension is 750 mm by way of example and the dimension in the transverse direction is 130 mm.

The vacuum flange 6 is mounted in a vacuum-tight manner in the chamber wall 30 of a vacuum chamber as a coating chamber.

A magnet system 3 is located outside the vacuum chamber. Correspondingly, pole shoes 7 are embedded in the vacuum flange 6 , as a result of which a higher and uniform field strength is achieved when a tunnel-shaped magnetic field 4 is formed above the surface of the target 1 .

Furthermore, a mechanically adjustable lifting system 32 is provided outside the vacuum chamber on the vacuum flange 6 , with which the distance between the magnet system 3 and pole shoes 7 can be adjusted depending on the target erosion, the target material or the technological requirements of the coating process. The Hubsy stem 32 is mounted on a mounting plate 25 which is attached to the vacuum flange 6 by means of supports 26 . A position sensor 19 is arranged on the mounting plate 25 , with which the position of the magnet system 3 can be determined.

The counter electrode 10 is formed in the example in parallel on both sides of the cooling plate 2 with the target 1 in the form of two elongated sheets and insulated on the vacuum flange 6 and arranged outside the area of the tunnelför-shaped magnetic field 4 .

An electrically insulated shield electrode 11 surrounds the target 1 and the counter electrode 10 and shields the space between the target 1 and the substrate 27 , with the exception of a steam outlet opening 31, essentially from the other areas of the vacuum chamber.

In the example, the shield electrode 11 is designed by an angling so that a gap 33 is formed between the shield electrode 11 and the outer plasma electrode 9 . This gap 33 depends on the practical circumstances and is in the range from approx. 5 mm to 20 mm, in the example it is 8 mm.

The outer plasma electrode 9 is arranged on the vacuum flange 6 in an electrically insulated manner. One of two parts of the outer plasma electrode 9 is arranged between the cooling plate 2 with the target 1 and the two parallel sheets of the counter electrode 10 . It is advantageous if the outer plasma electrode 9 completely surrounds the cooling plate 2 with the target 1 . In the example, the gaps 34 between the outer plasma electrode 9 and the cooling plate 2 with the target 1 are approximately 3 mm.

An inner plasma electrode 8 is arranged in an electrically insulated manner in the center of the target 1 . In Fig. 1 is the target 1 in cross-section Darge provides seren clarity. The target 1 is actually in one piece and has an opening for the inner plasma electrode 8 in the center.

The inner plasma electrode 8 and the outer plasma electrode 9 have a plurality of gas outlet openings 12 and 13 , respectively, which are connected to various gas supply devices with associated gas measuring devices 21 and control valves 22 . The plurality of gas outlet openings 12 and 13 is arranged in the longitudinal direction of the target 1 , so that a uniform inlet of argon as the working gas through the gas outlet openings 12 and of oxygen as the process gas through the gas outlet openings 13 is possible. The gas outlet openings 12 and 13 are arranged such that the gas inlet into the gaps 34 and 35 takes place between the cooling plate 2 with the target 1 and the outer plasma electrode 9 and the inner plasma electrode 8 . This type of gas inlet allows very short reaction times of the gas inlet system and thus very good process stability. However, it is also possible to let the gases into the space between the outer plasma electrode 9 and the shield electrode 11 .

Furthermore, 8 plasma screens 14 are arranged on the inner plasma electrode 14 and 15 plasma screens 15 are arranged on the outer plasma electrode 9 , which essentially cover the gaps 35 and 34 in the example. As a result, arc discharges, the formation of which in the area of high electrical and magnetic field strengths is particularly likely, can be avoided. It is also advantageous if corresponding apertures extend so far into the area above the target 1 that the non-eroding zones of the target 1 are partially or completely covered or reach up to about 1 mm from the erosion zone.

In the example, the counter electrode 10 was arranged such that the optical line between the target 1 and the counter electrode 10 is interrupted by the outer plasma electrode 9 . A coating of the counter electrode 10 with, for example, insulating aluminum oxide layers is prevented and long-term stability of the electrical function of the counter electrode 10 is achieved.

The cooling plate 2 with the target 1 and the counter electrode 10 are connected to a power supply device 5 via current feedthroughs in the vacuum flange 6 . This power supply device 5 supplies unipolar pulses with positive polarity on the counter electrode 10 and negative polarity on the cooling plate 2 with the target 1 .

The electrically insulated inner plasma electrode 8 and outer plasma electrode 9 , the counter electrode 10 and the shield electrode 11 are connected to an electrical network 23 with suitable resistors, capacitors, inductors and semiconductor components, which enables a defined potential setting. The vacuum flange 6 serves as a reference potential in this device. The potential setting depending on the size of the target 1 and the power fed in allows a significant reduction in arc discharges and a significant improvement in long-term stability, for example in the deposition of aluminum oxide layers. In the example, the network 23 defines the potentials when depositing aluminum oxide with a power of 15 kW as follows: counter electrode 10 : +30 V, inner plasma electrode 8 : +5 V, outer plasma electrode 9 : +10 V and shield electrode 11 : + 7 V.

Outside the vacuum chamber, a light sensor 18 is arranged, the signal of which is processed by converter electronics 24 and transmitted as a digital signal. The light emitted by the plasma discharge above the surface of the target 1 , enters a light entry opening 28 , a hole in the outer plasma electrode 9 with a diameter of about 4 mm, and passes through a light pipe 16 and a window 17 made of quartz glass , which seals an opening in the vacuum flange 6 , to the light sensor 18 . The light guide 16 is in the form of an internally polished metal tube with a free inside diameter of about 6 mm. The light guide device 16 is arranged insulated such that the outer plasma electrode 9 remains electrically insulated from the vacuum flange 6 .

Outside the vacuum, the light is guided from the quartz window 17 to the light sensor 18 via optical fibers. As an alternative embodiment, instead of the metal tube of the light guiding device 16, e.g. B. optical fibers can also be used.

The embodiment is further equipped with a pressure sensor 20 , which is connected to a pressure pipe 29 via a bore in the vacuum flange 6 . The pressure tube 29 has a free inner diameter of 15 mm and opens into the plasma space enclosed by the shield electrode 11 between the outer plasma electrode 9 and the counter electrode 10 . The opening of the pressure tube 29 ends close to a bore with a diameter of likewise 15 mm in the outer plasma electrode 9 , as a result of which the pressure in the plasma space inside the outer plasma electrode 9 can be measured directly.

The pressure tube 29 is electrically insulated. This ensures that the outer plasma electrode 9 is not electrically contacted with the vacuum flange 6 .

The pressure is preferably measured independently of the gas dependent by means of piezoelectric conversion.

The specific device for pressure measurement offers the advantage of greater accuracy with less time delay until the output of the measurement signal due to the direct measurement in the coating space enclosed by the shield electrode 11 compared to the usual pressure measurement in the vacuum chamber. The electrical signal of the pressure sensor 20 is converted by means of converter electronics 24 into a digital signal and forwarded to control and regulating electronics via an optical data transmission device.

Embodiment II

In embodiment II with the associated FIG. 2, an embodiment of the invention according to claim 3 is shown. As a counter electrode 10 according to game I, a target 40 of identical construction to target 1 is arranged. According to the invention, target 1, like target 40 , is arranged on a vacuum flange 41 as counter electrode 10 .

A shield electrode 42 encloses the entire arrangement of the device with the targets 1 and 40 on the vacuum side.

To measure the pressure, contrary to the game Ausführungsbei I, only an opening 36 in the vacuum flange 41 is present, the electrode 42 opens into the plasma space in the outer region within the screen.

The power supply device 37 is suitable for feeding the energy into the device in the form of bipolar pulses. One of the targets 1 and 40 is at least temporarily connected as a cathode and the other target 1 and 40 is connected as an anode.

The remaining components of the device essentially correspond to those in exemplary embodiment I with FIG. 1 and are provided with corresponding position numbers.

The device according to embodiment II has the advantage that the two targets 1 and 40 retain their electrical conductivity in the long-term stable at least in the area of the erosion zones, and the discharge conditions are therefore also long-term stable.

Embodiment II can also be modified under given conditions in such a way that the two targets 1 and 40 are arranged on two separate vacuum flanges. According to the invention, the entire device within the vacuum chamber is then surrounded by a common shield electrode. The individual other components of the device can be arranged variably on one of the vacuum flanges, unless they are required on both vacuum flanges.

The invention is of course not on the Darge laid out statements limited. It is so without further ado possible to vary individual components or more than Arrange two targets, these being variable as cathodes or anode can be switched.

Furthermore, it is also possible to replace the langge stretched rectangular geometry of the targets z. B. circle round, oval or triangular target shapes in adaptation to to choose the coating task. With circular tar getgeometry is in an advantageous embodiment of the Invention the inner plasma electrode also circular educated. Based on embodiment T is the target from the outer plasma electrode, the counter electrode trode and the shield electrode surrounded in a ring.  

List of the reference symbols used

1

Target

2nd

Cooling plate

3rd

Magnet system

4th

Magnetic field

5

Power supply facility

6

Vacuum flange

7

Pole pieces

8th

inner plasma electrode

9

outer plasma electrode

10th

Counter electrode

11

Shield electrode

12th

Gas inlet opening

13

Gas inlet opening

14

Plasma shutter

15

Plasma shutter

16

Light guide

17th

window

18th

Light sensor

19th

Position sensor

20th

Pressure sensor

21

Gas measuring device

22

Control valve

23

electrical network

24th

Transducer electronics

25th

Mounting plate

26

Support

27

Substrate

28

Light entry opening

29

Pressure pipe

30th

Chamber wall

31

Steam outlet opening

32

Lifting system

34

gap

35

gap

36

opening

37

Power supply facility

38

39

40

Target

41

Vacuum flange

42

Shield electrode

43

outer plasma electrode

Claims (7)

1. Device for magnetron sputtering, which is arranged on a vacuum flange, which is fixed in the chamber wall of a vacuum chamber opposite at least one to be coated, and consists of at least one thermally conductive target connected to a cooling plate and a counter electrode, both of which are on the vacuum flange are arranged within the vacuum chamber, and outside the vacuum chamber at least one magnet system arranged behind the target or the cooling plate for generating a tunnel-shaped magnetic field penetrating the target, preferably with ferromagnetic pole shoes, which are associated with the magnet system in the region of whose poles are vacuum-sealed in the vacuum are, and a power supply device with which the target and the counter electrode are electrically conductively connected via current feedthroughs in the vacuum flange, characterized in that

• an external plasma electrode ( 9 ) is present between the target ( 1 ) and the counter electrode ( 10 ) and is connected to a first optional potential,
• - That the counter electrode ( 10 ) is connected to a second optional potential,
• that an inner plasma electrode ( 8 ) is arranged in the center of the target ( 1 ) within the target area delimited by the erosion zone, said electrode being connected to a third optional potential,
• - That on the vacuum flange ( 6 ) to the substrate ( 27 ) open shield electrode ( 11 ) is arranged, which surrounds the target ( 1 ), the counter electrode ( 10 ), the outer plasma electrode ( 9 ) and the inner plasma electrode ( 8 ) and is connected to a fourth optional potential,
• - That on the inner plasma electrode ( 8 ) and / or the outer plasma electrode ( 9 ) there are preferably a plurality of gas outlet openings ( 12 , 13 ) which are connected to at least one gas supply device, and
• - That on the inner plasma electrode ( 8 ) and / or the outer plasma electrode ( 9 ) plasma screens ( 14 , 15 ) are present before, which at least partially cover the respective column ( 35 , 34 ) to the target ( 1 ).

2. Device for magnetron sputtering according to claim 1, characterized in that the counter electrode ( 10 ) and the outer plasma electrode ( 9 ) are arranged to each other in such a way that the optical line between the counter electrode ( 10 ) and the target ( 1 ) through the outer Plasma electrode ( 9 ) is interrupted. 3. A device for magnetron sputtering according to one of claims 1 or 2, characterized in that at least one further target ( 40 ) is present as the gene electrode ( 10 ), which is surrounded by a separate outer plasma electrode ( 43 ). 4. Device for magnetron sputtering according to one of claims 1 to 3, characterized in that outside the vacuum chamber, a light sensor ( 18 ) is provided, which is connected to a light guide device ( 16 ) which penetrates the vacuum flange ( 6 ) and their light entry opening ( 28 ) is located essentially at right angles to a line between the surface of the target ( 1 ) and the substrate ( 27 ) within the shield electrode ( 11 ). 5. Device for magnetron sputtering according to one of claims 1 to 4, characterized in that outside the vacuum chamber on the vacuum flange ( 6 ) there is a mechanically adjustable lifting system ( 32 ) with which the distance between the magnet system ( 3 ) and the pole pieces ( 7 ) is changeable. 6. A device for magnetron sputtering according to one of claims 1 to 5, characterized in that outside the vacuum chamber, a pressure sensor ( 20 ) is present, which via a pressure line ( 29 ) which penetrates the vacuum flange with the space inside the shield electrode ( 11 ) connected is. 7. Device for magnetron sputtering according to one of claims 1 to 6, characterized in that outside the vacuum chamber there is an electrical network ( 23 ) which consists of resistors, capacitors, inductors and / or active components such as voltage sources and which About electrical lines, which are inserted through electrical insulators in the vacuum flange ( 6 ) in the vacuum chamber, with the counter electrode ( 10 ), the outer plasma electrode ( 9 ), the shield electrode ( 11 ) and the inner plasma electrode ( 8 ) is connected.