CH702969A2 - Apparatus for treating and/or coating glass surfaces with thin layers using plasma, comprises anode segments, and a magnetic assembly, where the segment is based on magnetic field that forces electrons to sputter cathode - Google Patents

Abstract

The apparatus comprises segments (107) of anode (105), and a magnetic assembly, where the segment is based on a magnetic field. The anode segments have a magnetron-like magnetic field, which forces the electrons to sputter cathode (100) to the anode on a ring track through the anode segment. A gas inlet is present in the area of the anode or the anode segment. The magnetic assembly includes a permanent magnet and/or electric coils, where temporally variable and/or mechanically adjustable magnetic actuating elements are provided for controlling the permanent magnet and/or electric coils. The apparatus comprises segments (107) of anode (105), and a magnetic assembly, where the segment is based on a magnetic field. The anode segments have a magnetron-like magnetic field, which forces the electrons to sputter cathode (100) to the anode on a ring track through the anode segment. A gas inlet is present in the area of the anode or the anode segment. The magnetic assembly includes a permanent magnet and/or electric coils, where temporally variable and/or mechanically adjustable magnetic actuating elements are provided for controlling the permanent magnet and/or electric coils, so that the conditions in segments of the anode source/substrate interface are adjusted or regulated. The variable or the magnetic actuating elements are connected to sensor systems for detecting an actual value of the coating/etching conditions or connected to a loop segment to regulate or adjust the conditions in the anode source/substrate interface. The magnetic field strength of the each segments is independently controlled either by changing the coil current in the electric magnet or by a mechanical change in magnetic flux of permanent magnets. Each anode segment is controlled in its power consumption either by changing the impressed magnetic field or by time adjustable activation and deactivation of the segment to sputter current circuit. A regulated reactive gas is supplied in the anode segment, where the regulation serves as an adjustment of the current consumption. The gas flow is guided by the respective anode segment. The anode structure is cooled, has an integrated gas inlet system for an inert gas or the reactive gas, where the gas inlet fitting to the electrode parts is segmented, and is constructed as a ring arrangement around the coating source or as a separate element adjacent to the coating source, or in a geometrically separated ambient source. The segments of the anode electrode are separated by a narrow gap, where they are magnetically connected to each other. The individual segments are electrically isolated from each other. An independent claim is included for a method of treating and/or coating surfaces with thin layers using a plasma.

Description

The present invention relates to a device for treating or coating with thin layers of surfaces by means of a plasma according to the preamble of claim 1 and a method for treating or coating surfaces with thin layers by means of a plasma.

In reactive processes, a critical element is the anode. In the course of a coating campaign, this is, depending on the design, more or less coated with non-conductive material to complete isolation. This leads in the long term to unstable process control over the target lifetime and above all to local short-term inhomogeneities over the cathode length, which leads to uncontrolled Schichtinhomogenitäten on the substrate such as glass. The still insufficiently solved problem is also reflected in the large number of patents.

An additional problem with reactive sputtering is the delivery of reactive gas, such as e.g. Oxygen, which leads to partial target poisoning. Especially in very large coating chambers, as is customary in the glass industry, the gas diffusion is often not homogeneous due to pump geometry and process installations, which leads to non-uniform distribution of Raktivgas shares. This in turn can lead to, on the sputtering target, local oversupply of reactive gas. This in turn leads to locally changed sputtering rate (too much reactive gas drastically lowers the deposition rate). This results in locally different coating rates and thus layer thickness variations across the substrate width. In extreme cases, a sputtering cathode can work on one side of the target in the metallic mode and on the other side in the fully oxidized mode. One solution offered by equipment manufacturers is the division of gas inlets into sections. So it is customary to install 2 to 5 individual gas inlets in length. However, this solution is only of limited use, since due to the high velocity of propagation of the gases in vacuum, an exact influence on target sections is not possible, still impeded by partially substrates of different sizes, which constantly change the pump geometries in production.

A problem is also the crosstalk behavior with too much O2 use. Another undesirable effect is triggered by the chamber geometry of the coating systems for the large-area coating. The separation of the individual chambers is very incomplete, so that gas corrections in a process module lead to influences in the neighboring modules. Under these conditions, it is particularly important to process only minimal amounts of reactive gas in the process area.

Particularly harmful where the dielectric layers are to be deposited before or after purely metallic such as silver. To avoid discharge phenomena on the substrate such as the glasses, the anode is often electrically isolated from ground and placed near the cathode. This partly prevents the plasma environment on the substrate which is necessary for hard, scratch-resistant, dense layers.

About a bleeder, the potential of the anodes (thus also the floating potential of the glass surface) is set in the vicinity of the ground, for example, about + 0.5V in relation to the earth. This avoids flashovers from the charged glass surface to the mass. Locally, the anodes are positioned away from the glass surface to avoid higher plasma densities at the substrate surface.

For various layers, however, an increase in the plasma density in the layer growth zone is advantageous. The usual state of the art avoids this configuration.

On the subject of "vanishing anode" there are countless patents and publications, from "hidden anode" on foil anodes, which are rolled on to generate ever new surfaces, el. Connected, to exotic geometries, try this problem long-term stable to solve. Examples which may be mentioned here are the application DE 3 612 721 A1 or the US Pat. No. 5,897,753 "Dual-anode device".

A disadvantage of the newer method is the need for additional el. Circuits by resonant circuits, tuning capacitors, etc. that is, any new process or new target material requires a renewed, sensitive vote.

To solve the inhomogeneities on the cathode length, these methods do not contribute. The cathode discharge current is distributed over the entire anode length according to the principle of the least partial resistance and can thus lead to preferred areas of the discharge.

One approach to the topic of homogeneity of the discharge, for example, is to segment the anode, that is to divide the anode into several segments. For example, P. Sieck, Airco Coating Technology, Concord California proposes various ways of segmenting the anode in an article of Society of Vacuum Coaters 505 / 586-7188, 37 Annual Technical Conference Proceedings (1994) 1-878068-13-X or provide a plurality of anodes. According to a proposed solution, each anode segment is electrically connected individually. According to a further proposal, a so-called "dual-cathode system" is proposed with a plurality of anodes, wherein anodes are provided between two tubular magnetron-type cathodes, and laterally to the magnetron tubes.

Accordingly, it is known to take an influence on the layer thickness distribution by dividing anodes and different wiring of these divided anode segments. However, this method requires a temporally constant division of the electron currents to the corresponding segments, so that predictable corrections can be made.

As already described above, the possibility of partially covering target surfaces differently with an oxide skin is solely due to a slightly uneven distribution of the reactive gas. These sites have a different secondary electron emission and thus a partially different current density. This changes the current output to the anode assignment next to the adjacent anode segment over the duration of the process. These partial occupancies are not predictable or even controllable, so that uncontrollable temporal fluctuations of the current flow per segment occur.

In practice, however, and especially in sputter cathodes extreme unpredictable Plasmadrifts are observed. This leads to the fact that the individual segments must deal with very different electron currents. The result is that a switched segment once again shows less effect, depending on the phase of the oscillating plasma density. This effect is further enhanced by the geometric change of the anode surface through the coating process, especially when non-conducting dielectrics are sputtered.

Due to the inhomogeneous plasma loading of the anode geometries, the reliable control of anode segments as described in the article by P.Sieck Airco Coating Technology in a production for optical layers is not possible because the same anode segment times more times receives less electron current, with very different Frequencies, some with jumpy transitions.

For linear magnetron arrangements over several meters in length, e.g. more than 3 m, this effect is even more pronounced.

This means a Beschälten one or more anode segments leads time and again to other, unpredictable control results.

All together results in a very inaccurate control option. This may also be the reason that this method of segmentation of anodes, although long known, has not been used in the industry.

For several years, it is known to increase the plasma density at the substrate in magnetron discharges by means of unbalanced Magnetsytemen and closed field magnet arrangements. The disadvantage of these methods is, on the one hand, that once the unbalanced magnet system has been set, it is fixed for all coating cycles, that is, layers which are disrupted by unbalanced design in growth, such as, for example, ITOs must be processed with a second cathode, so they can not be treated in the same environment. Furthermore, a close field arrangement in a Durchlaufanläge where the cathodes are arranged in a plane, so not practicable, so here always results in a magnetic opening to the recipient and such a dense plasma confinement is not possible.

Furthermore, in addition to the magnetron coating source plasma or ion sources or so-called Plasmathruster be used. Here, additional installation space for the new complex expensive ion source with power supply, gas system and so on is necessary. In addition, the ions generated thereby have energies in the range of a few hundred electric volts, which leads to destruction or defects in certain layer growth conditions.

In addition, in comparison to the patent application presented here, the abovementioned applications have only a fraction of the carrier densities in the region of the layer growth zones on the substrate.

In the publication in J. Vac. Sci. Technol. A 14 (4) Jul / Aug. 1996 by W.H. Tao et al., Spatial Distributions of Electron Density and Direct Current Glow Discharge, describes a magnetic field assisted anode with corresponding plasma behavior measurements in the cathode anode environment.

The same is mentioned in International Application WO 2008/118 203 A2 to J. Madocks, where an arrangement is described which operates an anode in conjunction with a magnetron, the anode having a magnetron-like magnetic field. The structure is such that the electrons from the magnetron discharge are controlled by a magnetic field before reaching the anode surface, whereby an additional increase in ion density is achieved. This anode can not and will not be used for local plasma density corrections due to plasma density variations. The disadvantage here is that even slight inhomogeneities of the gas flow in the source plasma density fluctuations occur, which lead to the influence of coating distributions.

The also previously described ions or Plasmathruster sources have the disadvantage of high ion energies of several 100 electric volt and low current density.

Accordingly, it is an object of the present invention to provide a long-term stable arrangement, which allows control options with respect to layer homogeneity, and allows the largest possible activation of reactive gas, with the additional ability to influence the plasma conditions such as ion current densities, ion energies on the substrate in a positive manner. Another task is the controllable surface engineering of growing sputter layers.

According to the invention, an apparatus for treating or coating surfaces with thin layers by means of a plasma according to the wording of claim 1 is proposed.

Proposed is the use of a device which is connected in an equipped with a plurality of electrode coating arrangement as the anode.

According to the invention it is proposed that at least one of the anode segments has a magnetron-like magnetic field which forces the electrons on their way from the sputtering cathode to the anode on a circular path over the anode electrode and a current density compensation is achieved by this movement in the ring path. In other words, a magnet arrangement is provided at least on one segment of the anode or this segment is supported by magnetic fields. According to one embodiment, all the anode segments are provided with a magnetron-like magnetic field, whereby a current density compensation of the individual segments is achieved with each other.

For improved controllability of the transverse distribution, the anode electrodes are segmented, that is electrically separated from each other, but magnetically interconnected.

The anode segments can be acted upon by a magnetron-like magnetic field, so that a circulating electron flow takes place in the anode plane, which minimizes the disadvantage of the plasma fluctuation by this ring current.

Advantageously, the magnetic field strength is also adjustable, e.g. by el. coils or a combination of permanent magnets with additional el. coils or by mech. movable passive or active magnetic field variable elements.

The magnetic field strength of the individual segments can be controlled independently of one another.

In the case of the use of a reactive gas, this is proposed to lead in the region of the anode or one or more of the anode segments. For example, the gas inlet reactive and / or inert is passed directly through the anode.

It is advantageous that per segment, the reactive and or inert gases are provided with its own scheme. Thus, it is also possible to influence current density fluctuations and layer thickness distributions per target section very effectively by the increased reactivity in the plasma.

Each individual anode segment can be controlled in its current consumption, either by changing the embossed magnetic field or by time-adjustable switching on and off of the segment to the sputtering circuit, or in another embodiment by the controllable segmented gas flow, which is guided for example through the anode segment ,

By using, for example, with special electronics with intelligent software, the individual segments can be switched off or pulled over pulse-pause ratios, so that the discharge circuit and thus the plasma density can be varied locally.

Another option is to change the segmented, supporting magnet arrangements. By amplifying or weakening the magnetic field strength in the corresponding segment, the associated impedance is changed and thus the division of the discharge current and thus the plasma density is achieved.

It is also possible to combine both methods, that is, magnetic and electrical control.

The cooled anode structure may have an integrated gas inlet system for inert gases, such as argon or reactive gas such as oxygen, hydrogen or even HMDSO, TEOS and so on. Also, the gas inlet can be made segmented to match the electrode parts.

Reference to the accompanying figures, the invention will be explained in more detail, for example.

[0041] <Tb> FIG. 1a + 1b <sep> schematically in plan view and in section a possible arrangement of a novel cathode-anode arrangement, <Tb> FIG. 2a-2c <sep> another possible embodiment in plan view and in section, <Tb> FIG. 3a to 3c <sep> again schematically possible arrangements of cathode and segmented anode in plan view, <Tb> FIG. 4a to 4c <sep> schematically in section further possible embodiments of cathode and segmented anode, which are adaptable in their mutual height, <Tb> FIG. 5, 6 and 7 <sep> again possible geometries of segmented anodes for a coating apparatus according to the invention, <Tb> FIG. 8 and 9 <sep> in cross-section and in top plan view schematically embodiments of a coating system according to the invention for coating, for example, a large-area substrate such as glass and <Tb> FIG. 10 <sep> on average a possible arrangement of magnets in an anode segment.

The interaction of charge carrier generating source such as sputtering cathodes, ARC evaporator or low-voltage arc discharge sources with filament-assisted electron emission, hollow cathodes, microwaves or high frequency plasma generation can be done in a variety of configurations.

In principle, a wide variety of charge generators can be interconnected with the novel anode concepts.

DC / RF / MF pulsed sputtering cathodes or ARC evaporators in round, rectangular or otherwise suitable form.

In Fig. 1a, a possible arrangement of an inventive coating system is shown schematically in plan view.

In principle, the arrangement according to the invention consists, for example, of a sputtering cathode 100, which is coupled to a segmented anode 105 via a power supply 102 and an intelligent anode segment drive 104. The anode 105 consists of the individual juxtaposed segments 107, which are electrically isolated from each other, but of a magnetic field which is superimposed over the individual segments. At the respective end segments, a magnetic inclusion is schematically visible.

FIG. 1b shows a sectional perspective of the anode 105 from FIG. 1a. Recognizable are the individual anode segments 107, which are covered by corresponding permanent magnets 109 above covered quasi to form a magnetic field. Via terminals 106, the individual anode segments are connected to the anode segment drive 104. Finally, it can be seen a gas inlet III for charging the anode, for example. With an inert gas.

Typical process parameters for such a plant are e.g. U = 550V; I = 2-25a; 4x10-3mbar argon inert gas.

A further embodiment is shown schematically in Figs. 2a-2c, where a low-voltage arc source with different electron emitters such as filament, hollow cathodes, etc. are operated.

According to Fig. 2a, the current flow from a cathode 100, for example. Having a so-called filament. Contrary to the representation in FIG. 1, the individual anode segments 107 of the segmented anode 105 are individually surrounded by permanent magnets 109. The arrangement of the individual anode segments 107 can be clearly seen in a longitudinal section along the line II-II, as shown in Fig. 2b.

Finally, FIG. 2c shows the segmented anode in a longitudinal perspective, in which representation in particular the arrangement of the magnets 109 can be clearly seen.

Usual Prozessparamenter such a system are U = 120V; I = 25-200A; 3x10-3mbar argon.

Also in the generators DC / MF / RF pulsed low-voltage arc discharges or high power pulse can be used.

In the segmented anode sputtering cathodes configuration, pulsed generators are preferably used with variable pulse frequencies in the range of 0 to 350KHz.

In turn, further possible arrangements according to the invention are shown schematically in plan view in FIGS. 3a to 3c.

According to FIG. 3 a, the arrangement of the anode segments can take place unilaterally next to the electron / plasma generator source. This arrangement can also be used if the generator and segment anode are e.g. are installed in separate compartments with sufficient pumping slots in between. Thus, in practice, a distance of 1.40 m with opening slits of about 5 cm over a substrate height of 60 cm could be realized very successfully.

Furthermore, the segmented anode elements may be positioned on both sides or in addition to the end faces of the generator source, as shown schematically in Fig. 3b.

Preferably, the anode structure has a magnetically coupled racetrack 114, as shown in Fig. 3c, but mechanically and electrically segmented.

The installation position can take place flat at the level of the generator source, as shown for example in FIG. 4 as a schematic diagram or offset forwards in the direction of the substrate 120 for increasing the ion density as shown in FIG. 4b. Or set back, as shown schematically in Fig. 4c, to obtain the high reactive gas excitation, but not the high ion bombardment in the layer growth zone.

The anode geometry can be constructed in a rectangular or round shape. The individual segments can also have rectangular or round shapes.

Fig. 5 shows an example of a preferred anode form, which is constructed circumferentially around the sputtering cathode, so that a second magnetic tunnel for electrons for the sputtering cathode is formed.

FIG. 7 shows a similar structure for round sputter sources.

Fig. 6 shows individual round anode segments, but in themselves have a magnetic tunnel similar to a round magnetron structure.

The anode structure can be constructed, for example, as a ring arrangement around the coating source such as sputtering source, ARC source, high-current plasma source, etc. or as a separate element directly next to the coating source or even in a geometrically separated environment from the sources.

It is conceivable to build a loop via in situ sensors, so that a readjustment of the plasma conditions can be achieved depending on the local conditions. These sensors can be Langmuirsonden or quartz crystals for coating thickness measurement or optical sensors.

Fig. 8 shows in section and schematically an inventive coating concept for coating, for example, a glass plate 22 with a thin layer. The coating takes place by means of a sputtering process, wherein the plasma is generated by means of a magnetron cathode 3 and a segmented anode 5, which via electrical connections 2 respectively. 6 are connected to a Sputterpowersupply 8 for generating the plasma 21. The segmented anode is an annular anode, which can be seen better in plan view in FIG. 9. The anode 5 consists of individual segments 1, 1, 1, etc., each segment being electrically controllable individually via terminals 6, 6, etc. (by an anode control 4). As can be clearly seen in particular in FIG. 9, the individual segments are separated from one another by narrow gaps 13 of approximately 1-3 mm, but are magnetically connected to one another. For this purpose, each segment for generating a magnetic field 24 is provided with a magnet 9, consisting of laterally arranged legs for north and south pole.

Finally, the individual anodes 5 can be arranged in an insulation space such as, for example, a so-called dark room 26 for preventing flashovers. For example, non-magnetic steel can be used for this purpose.

As already mentioned above, it can be advantageous if an inlet 11 for reactive gas or inert gas takes place directly through the anode, as indicated in FIG. 8 by the reference numeral 11.

The substrate 22 such as a glass plate may be moved through the plasma 21 below the segmented anode to be coated with a thin layer. The glass plate or glass pane can be continuously coated or treated by being moved through the plasma below the anode.

As shown in Fig. 10, the anode segments may be provided with both a permanent magnet 31, as well as with a coil 33 for the electrical generation of a magnetic field 36 between the two poles 35 and 37. It is also possible, both a permanent magnet as well as to arrange an electric coil at the same time to influence the strength of the magnetic field during the coating process.

The magn. Field strength in the region of the anode can range from 10 Gauss to 800 Gauss, depending in part on the electron emission sources used. Thus, when using sputtering magnetrons, a field strength of 100 Gauss to 800 Gauss, preferably one of 350 Gauss to 650 Gauss use.

When using low-voltage arc discharges or other low-voltage sources, field strengths of 10 Gauss to 500 Gauss, preferably 50 Gauss to 250 Gauss are sufficient.

In practice, it has now been shown that in order to achieve a homogeneous and consistent layer thickness, the various parameters, such as the generation of the magnetic field as well as the electrical control of the various anode segments must be constantly adjusted, as keeping the various settings with layer thicknesses constant and layer quality fluctuations can be expected.

The arrangements for generating a plasma shown in the figures are, of course, only examples to illustrate the present invention. Of course, modifications of the system such as geometry of cathode and anode are possible, as well as the equipment can be supplemented by other elements.

Claims (22)

1. An apparatus for treating and / or coating surfaces with thin layers by means of a plasma, characterized by a segmented anode, wherein at least on a segment of the anode, a magnet arrangement is provided or this segment is magnetic field supported. 2. Apparatus according to claim 1, characterized in that at least one anode segment has a magnetron-like magnetic field, which forces the electrons on their way from a sputtering cathode to the anode on a circular path through the anode segment. 3. Apparatus according to claim 1 or 2, characterized in that in the region of the anode or an anode segment, a gas inlet is guided. 4. Device according to one of claims 1 to 3, characterized in that the magnetic configuration at the one or the anode segments consists of at least one permanent magnet and / or electric coil or a combination of the two. 5. The device according to claim 4, characterized in that temporally variable and / or mechanically adjustable magnetic adjusting elements for controlling the permanent magnets and / or electrical coils are provided so that the conditions on the anode source / substrate surface are adjustable or adjustable in segments. 6. The device according to claim 5, characterized in that the variable or adjustable magnetic adjusting elements are connected to one or more sensor systems for actual value detection of the coating / or Ätzbedingungen to a control loop to set the conditions at the anode source / substrate surface segmentally or regulate. 7. Device according to one of claims 1 to 6, characterized in that at least two or all anode segments have a magnetron-like magnetic field, which forces the electrons on their way from a sputtering cathode to the anode on a circular path and minimized by this ring current fluctuations on an anode segment. 8. Device according to one of claims 1 to 7, characterized in that the magnetic field strength of the individual segments can be controlled independently of one another either by changing the coil current in electric magnets or by mechanical change of the magnetic flux in permanent magnets. 9. Device according to one of claims 1 to 8, characterized in that each individual anode segment is controllable in its current consumption either by changing the impressed magnetic field or by time-adjustable switching on and off of the segment to the sputtering circuit. 10. Device according to one of claims 1 to 9, characterized in that at least one or per segment, a regulated gas addition is provided, preferably an addition of a reactive gas, wherein the control can serve as an adjustment of the power consumption. 11. Device according to one of claims 3 to 10, characterized in that the segmented gas flow is controllable, which is guided by the respective anode segment. 12. Device according to one of claims 3 to 11, characterized in that the anode structure is cooled and has an integrated gas inlet system for inert gases or a reactive gas, wherein the gas inlet is segmented to match the electrode parts. 13. Device according to one of claims 1 to 12, characterized in that the anode structure is constructed as a ring assembly to the coating source or as a separate element directly adjacent to the coating source or in a geometrically separated from sources environment. 14. Device according to one of claims 1 to 13, characterized in that the segments of the anode electrodes are separated by a narrow gap, but are magnetically interconnected. 15. Device according to one of claims 1 to 14, characterized in that the individual segments are electrically isolated from each other. 16. A method for treating and / or coating surfaces with thin layers by means of a plasma, characterized in that the plasma conditions are controlled by the segmentation of an anode, wherein at least a portion of the segments of the anode is magnetic field assisted. 17. The method according to claim 16, characterized in that in the anode segments, a magnetron-like magnetic field is constructed, which forces the electrons on their way from the sputtering cathode to the anode on a circular path through all anode segments and by this movement in the circular path a strong increase in the charge carrier density produced and additionally achieved by the resulting ring current homogenization of the charge carrier density ratios over the anode length. 18. The method according to any one of claims 16 or 17, characterized in that the plasma control or homogeneity of the layer structure is controlled by independently controlling the magnetic field strength of the individual anode segments by the coil current is changed in electric magnets or by the magnetic flux is changed in permanent magnets. 19. The method according to any one of claims 16 to 18, characterized in that the plasma control or influencing the layer homogeneity during coating, the current consumption of each anode segment is controlled either by changing the impressed magnetic field or by temporally adjustable switching on and off of the segment to the sputtering circuit or by controlling the gas flow through the anode segment. 20. The method according to any one of claims 16 to 19, characterized in that in addition to the coating, a surface treatment of the substrate is carried out by the anode is arranged locally separated from the cathode and first the substrate passed on the anode is surface-treated, such as etched, chemically activated, for example oxidized with oxygen or reduced with hydrogen and then the coating takes place when passing through the cathode. A method according to any one of claims 16 to 20, characterized in that a combined PVD + CVD process is performed by the sputtering cathode performing the physical coating and separately separating the plasma enhanced anode by adding precursors such as e.g. HMDSO or other common in CVD technology gases or liquids, a deposition from the gas phase with plasma support takes place. 22. The method according to any one of claims 16 to 21, characterized in that metal deposits take place in activated oxygen, nitrogen or hydrogen atmosphere.