WO2004094686A2

WO2004094686A2 - Device for coating a stationary substrate by pulse magnetron sputtering

Info

Publication number: WO2004094686A2
Application number: PCT/EP2004/002332
Authority: WO
Inventors: Peter Frach; Klaus Goedicke; Christian Gottfried
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2003-04-23
Filing date: 2004-03-08
Publication date: 2004-11-04
Also published as: JP2006524291A; DE10318364A1; WO2004094686A3

Abstract

The invention relates to a pulse magnetron sputtering device containing: a recipient (1) with a vacuum generating system; two magnetron sputtering sources (7, 8); at least one substrate holder (15), and; a power supply device. Said recipient, in one sectional plane, comprises a pentagonal cross-section that has at least one right angle. A magnetron sputtering source is mounted on each of the lateral walls (2, 3) that are situated at right angles to one another. The three remaining lateral walls (4-6) are each provided with an opening and associated flanges (16-18). At least one opening of one lateral wall located opposite a magnetron source is sealed via vacuum flanges comprising means for freely positioning the substrate holder either directly opposite the middle (20) of the opposing magnetron sputtering source or parallelly offset with regard to the middle of the source, and the power supply device is equipped with means for the magnetron sputtering sources. These means permit the supply of unipolar power pulses having a frequency ranging from 1 to 100 kHz in each source with a separately settable power and with a separately settable pulse ratio or permit the supply of bipolar power pulses having a frequency ranging from 1 to 100 kHz with, for each polarity, separately settable power and separately settable pulse ratio.

Description

Device for coating a stationary substrate by pulse magnetron sputtering

The invention relates to an arrangement for pulse magnetron sputtering, preferably for the deposition of multilayer systems, so-called multilayer arrangements, in thin-film technology on stationary substrates. The arrangement is particularly suitable for carrying out research and development work in thin-film technology with several freely selectable coating parameters.

Magnetron sputtering, often referred to as cathode sputtering, has found widespread use among physical vacuum coating processes (PVD). Since the introduction of the pulse magnetron sputter, in which the energy is fed into the magnetron discharge at a frequency of approx. 10 kHz to 350 kHz in the form of direct current pulses, sinusoidal alternating current or bipolar pulses, the range of applications has been further increased and also for separation electrically insulating chemical compounds with a high deposition rate. This requires reactive process control with active control of the reactive gas flow or the reactive gas pressure. Pulse magnetron sputtering also offers the possibility of influencing the structure and properties of the deposited layers in the desired manner by defining suitable pulse parameters such as frequency, pulse shape and duty cycle, in addition to the coating parameters which are known per se. The duty cycle is understood to be the quotient of the pulse on time and the entire pulse length including the pulse pause. The large number of variable manufacturing parameters and a comparatively complicated process control often require that research and development work be carried out to optimize the deposition process before using the pulse magnetron sputter.

Vacuum coating systems of very different types are known in which such research and development work can be carried out successfully. Standard components, such as magnetron sputter sources of mostly round design, substrate holders and pulse power supply units, components for the pretreatment and heating of one or more substrates and measuring devices are arranged in mostly geometrically simple-shaped recipients with vacuum generation and system control units, at low cost for to achieve such research facilities. For the deposition of layer systems that consist of several layers or that By simultaneously sputtering with several magnetron sources, so-called “co-sputtering”, arrangements of a stationary substrate and several magnetron sources with circular, flat or profiled targets were frequently used, in which the target surfaces of the magnetron sources are essentially aligned with the center of the substrate Arrangements with a turntable are also widespread, through which the substrate or substrates can be guided one or more times in succession vertically over each of the magnetron sources. In particular, these two widespread arrangements are linked with an often insufficient range of variation of the coating parameters a comparatively large recipient and is accordingly expensive.

A larger number of other special arrangements of the components for magnetron sputtering in a research facility can be found in the scientific literature (for example Thin Solid Films "," Surface Coating Technologies "," Vacuum in Practice "), but without the the desired freedom of choice of the coating parameters and the pursuit of the lowest possible investment costs would have been sufficiently combined. As a consequence, there is often a lack of technological flexibility of the magnetron sputtering system or an insufficient scalability of the process optimized with the research and development system during the transfer to Industrial coating practice In particular for the development of coating processes based on pulse magnetron sputtering, such deficits often come to light and complicate or prevent the success of research and development work.

It is therefore an object of the invention to provide an arrangement for pulse magnetron sputtering which, with little technical effort, permits high flexibility in the coating of stationary substrates by pulse magnetron sputtering with a large freedom of choice of the pulse parameters and the layer properties. The deposition of individual layers as well as of multilayer, gradient and mixed layers should also be possible.

The object is achieved by an arrangement for pulse magnetron sputtering with the features according to claim 1. Claims 2 to 5 describe further advantageous refinements of the device according to the invention.

The device according to the invention comprises at least one recipient with a vacuum generation system, at least two magnetron sputter sources with round or right angular targets, magnet arrangement, gas inlet and gas control system, at least one substrate holder for receiving one or more substrates during the coating, at least one power supply device with control or regulating systems and a control device. According to the invention, the recipient has a pentagonal cross section in a sectional plane, which comprises at least a right angle. It is particularly expedient if it is delimited parallel to this plane by a flat base or cover plate on which the side walls are perpendicular. In this case, the outer shape of the recipient body corresponds to a five-sided prism. It is advantageous if the five side walls are arranged with respect to one another in such a way that at least two side walls face each other in parallel. It is particularly advantageous if the five side walls are arranged such that they enclose three right angles and two obtuse angles. A magnetron sputtering source is attached to each of two side walls at right angles to each other. In addition to the rectangular or circular target with cooling device, the magnet arrangement, a gas inlet and gas control system, the magnetron sputter sources each have a separate anode. The three remaining side walls, at least one of which runs parallel to a wall that carries a magnetron, each have a flange opening that is suitable for mounting a substrate holder. At least the opening in the wall arranged parallel to a wall with magnetron is sealed with flanges which have means for the optional positioning of the substrate holder in relation to the center of the opposite magnetron sputter source.

An advantageous embodiment of the invention consists of arranging a magnetron source on each of the two large side walls which are perpendicular to one another. In addition to the rectangular or circular target with cooling device, the magnet arrangement, a gas inlet and gas control system, the magnetron sputter sources each have a separate anode, which is largely protected against a coating. The three remaining side walls each have a flange opening that is suitable for mounting the substrate holder. These flange openings and the centers of the magnetron sputter sources lie in a plane which forms a pentagonal cross section through the recipient.

At least the flange openings opposite the magnetron sources are sealed with vacuum flanges which have means for the optional positioning of the substrate holder in relation to the centers of the magnetron sputter sources. For this purpose, two eccentric flanges arranged one above the other and rotatable relative to one another are arranged. The Eccentric flanges have rotationally symmetrical openings, the center of which is offset from the center of the flange. The position of the substrate holder in the plane of the centers of the magnetron sputter sources can thus be adjusted such that the center of the substrate holder is offset from the center of the opposite magnetron sputter sources or is positioned directly opposite it. The substrate holder is equipped with means for setting the target-substrate distance. They are designed so that an optional positioning of the substrate center at a variable distance, for. B. in the range of 50 mm to 250 mm, to the centers of the target surfaces of the magnetron sputter sources.

According to the invention, the power supply device for the magnetron sputter sources allows energy to be fed in separately at a frequency in the range from 1 kHz to 100 kHz, each with individually adjustable current strength, power or voltage and individually adjustable ratio of pulse on time to pulse off time , The associated “hidden anode” is connected as the respective counter electrode. The power supply unit is further configured such that alternatively the feeding of bipolar power pulses with a frequency of 1 kHz to 100 kHz and with power that can be set separately for each polarity and separately adjustable ratio of Each of the magnetron targets is connected to one pole of the power supply device in such a way that the targets are alternately connected as cathode and anode of the magnetron discharge for pulse magnetron sputtering means to switch between the feeding of unipolar power pulses and bipolar power pulses into the magnetron sputtering source at any time The freedom of choice of the mode of the power pulses and the ratio of pulse on time and pulse off time means that the setting is the Bombardment intensity d he growing layer on the substrate possible by charged or high-energy species from the plasma within wide parameter limits. In this way, the structure and the physical properties of the layer and, depending on it, numerous applicative layer properties can be influenced and optimized in the desired sense. The inventive choice of the coating geometry and the freedom of choice

The substrate position in relation to the distance and angular position relative to the magnetron sputter sources is the reason for the wide range of uses of the sputtering device for the deposition of layers and layer systems under the most varied of conditions. By changing the eccentric parameters of the substrate position relative to a magnetron sputter source, z. B. Important parameters of plasma activation of the condensation Process vary and thus very rationally set or determine an optimum for the respective coating task.

The variability relates to the layer materials, the growth rate, the direction of incidence of the layer-forming particles, the degree of activation of the deposition process by the plasma and many other parameters. The deposition conditions can be controlled as a function of time, and predetermined gradients of the layer properties can thereby be set. The possibility of co-sputtering is particularly advantageous in order to produce new material combinations from different starting materials in a strictly controllable manner using purely electrical setting parameters. The arrangement is also outstandingly suitable for the deposition of multilayer systems (multilayer).

In an advantageous embodiment, each magnetron sputter source is assigned a shutter, which can preferably be moved in a plane parallel to the respective surface and in the longitudinal direction of the recipient. This enables a multilayer system with abruptly changed layer properties at the interface between the individual layers to be achieved with high homogeneity of the layer properties in each individual layer. It is advantageous to equip the device according to the invention in the area of the magnetrons with the mechanical quick-closing diaphragms which are driven electro-pneumatically. In particular for research and development tasks, the device according to the invention advantageously has at least one further vacuum flange for mounting means for in-situ measurement of a plasma parameter, such as, for example, B. plasma potential and / or optical emission or a layer property and / or for the implementation of plasma diagnostic measuring means, such as. B. for energy dispersive mass spectrometry. A further advantageous embodiment consists of an opening in a side wall, which is prepared for receiving the substrate holder, but is not required for the respective coating task, for mounting an energy-dispersive mass spectrometer, with which the effect of differently set parameters to support the process optimization Energy feed can be measured based on the type, density and energy distribution of the plasma species.

In the interest of high homogeneity of the layer properties on the substrate, an advantageous device according to the invention is equipped with means for rotating the substrate about an axis parallel to its normal. An equivalent and advantageous solution in the sense of the invention is also to be regarded as a device which is not only for the coating of a single substrate per coating cycle is provided, but instead is equipped with a substrate lock and changing devices for substrates and thus allows the coating of many substrates in succession.

The device according to the invention is explained in more detail using an exemplary embodiment.

Place in the accompanying drawings

Fig. 1 shows the cross section through the recipient in a plane that the middle of the

Includes magnetron sputter sources, and Fig. 2a and 2b block diagrams and pulse patterns for the energy feed into the

Magnetron sputtering sources in the form of unipolar or bipolar

Power pulses.

Fig. 1: A recipient 1 of a device according to the invention is delimited by side walls 2, 3, 4, 5, 6 and by a base and a cover plate (parallel to the plane of the drawing, not shown here) and has the cross section of a symmetrical pentagon with only one axis of symmetry. The side walls 2 and 3 form one another and with both adjacent side walls and the side walls 4, 5 form a right angle with one adjacent side wall each. The five side walls are so arranged that they enclose three right angles and two obtuse angles.

The side walls 4 and 5 form an obtuse angle of 135 ° with an adjacent side wall. The side wall 6 forms an obtuse angle of 135 ° with both adjacent side walls. The recipient is evacuated from a vacuum generation system with a turbomolecular pump, and a gas inlet system is designed to set a suitable working pressure for argon gas.

The side walls 2 and 3 have openings for receiving a magnetron sputter source 7 and 8, respectively. Each of the magnetron sources has a target with a cooling device 9 or 10, a gas inlet and gas control device for one or more reactive gases, e.g. B. oxygen and nitrogen, and shielding plates 1 1 and 12, which limit the plasma space in the vicinity of the targets. Outside the shield plates, both magnetron sputter sources each have an electrode 13 or 14, which is largely protected against a coating. Such so-called hidden anodes are known from DE 42 23 505 C1 and DE 199 47 932 C1 / DE 199 47 935 A1. The side walls 4, 5, 6 are each provided with an opening which is prepared for receiving a substrate holder 15. The middle this opening and the centers of the magnetron sputter sources lie in a plane which corresponds to the recipient cross section, in the present example in the plane of the drawing. The openings are each sealed with a pair of eccentric flanges 16, 17, 18. These eccentric flanges can be installed at different angles to each other. In this way, the position of the substrate holder 15 can be set as desired. With the

Eccentric flanges 16 and 18, the center of the substrate holder 19 can be positioned directly opposite the center of the magnetron sputtering source 20 opposite each other. However, it is also possible to set an offset of the normal of up to 100 mm. The mounting of the substrate holder in the position 15 in the opening of the side wall 6 is best suited if a mixed layer of chemical compounds of both generally different target materials is to be produced by co-sputtering the targets 9 and 10. The substrate holder is mounted on a corrugated tube body 21. As a result, the distance b between the center of the substrate holder 19 and the center of the magnetron sputtering source 20 can be set in the range between 50 mm and 50 mm.

A power supply device (not shown here) for the magnetron sputter sources is equipped with means which allow unipolar power pulses or alternatively bipolar power pulses to be fed in. The pulse frequency is variably adjustable between 10 kHz and 50 kHz. The ratio of pulse on time and pulse off time can be set independently for each target in a ratio of 1:10 to 10: 1 for both modes.

The device according to the invention is further equipped with mechanical quick-closing orifices 22 and 23 which are driven electro-pneumatically. They are required so that the device for the deposition of multi-layer systems with sharp interfaces, i. H. abrupt transitions between the individual layers can be used. The opening in the side wall 5, which in the example is not required to accommodate the substrate holder, is used to mount an energy-dispersive mass spectrometer 24, with which the effect of differently set parameters of the energy feed on the type, density and energy distribution of the plasma species can be measured to support the process optimization ,

The block diagram for the feeding of unipolar power pulses and the resulting pulse pattern can be read from FIG. 2a. Two direct current sources 31 and 32 in connection with a switching unit 33 both feed magnetron sputter sources. The target of the one source forms the cathode 35, the “hidden” electrode of the source the anode 34 of the first magnetron discharge.

The target of the other source acts as cathode 37, the “hidden” electrode of this source acts as anode 36 of the second magnetron discharge. The associated patterns of the current pulses 38 and 39 are in the example with respect to the frequency as well as the amplitude and the ratio of pulse -On-time and pulse-off-time set differently according to the coating task.

2 b shows block diagrams and pulse patterns for the mode of energy feed into the magnetron sputter source in the form of bipolar power pulses. The same two direct current sources 31 and 32 and the switching unit 33 with the integrated switching device for the pulse mode feed bipolar energy pulses in the double arrangement of the two magnetron sputter sources.

The targets alternately act as anode and cathode of a common magnetron discharge, the “hidden” electrodes are not electrically connected to the power supply and are therefore not shown in FIG. 2b. The resulting pulse pattern 40 shows that here too pulse length and amplitude for both magnetron The switchover between the two pulse modes according to the circuit in FIGS. 2a and 2b is possible at any time under program control.

Claims

claims

1. Device for pulse magnetron sputtering, containing a recipient with a vacuum generation system, two magnetron sputter sources, at least one substrate holder and a power supply device, wherein

the recipient has a pentagonal cross section in a sectional plane, which comprises at least a right angle,

- A magnetron sputter source is attached to each of the two right-angled side walls, - The three remaining side walls are each provided with an opening and associated flanges, such that at least one opening of a side wall opposite a magnetron source is sealed with vacuum flanges, the means for optional positioning of the substrate holder either directly opposite the center of the opposing magnetron sputter source or offset parallel to the center of the source,

the substrate holder is equipped with means for the optional positioning of the substrate center at a variable distance from the target surfaces of the magnetron sputter sources,

- The power supply device for the magnetron sputter sources is equipped with means for feeding unipolar power pulses with a frequency in the range of 1 ... 100 kHz into each of the sources with separately adjustable power, separately adjustable ratio of pulse-on-time to pulse -out-time or alternatively the feeding of bipolar power pulses with a frequency of 1 ... 100 kHz with separately adjustable power for each polarity and separately adjustable ratio of pulse-on-time to pulse-off-time, the targets of

Magnetron sources are connected to one pole of the power supply device in such a way that targets are alternately connected as cathode and anode of the magnetron discharge.

2. Device for pulse magnetron sputtering according to claim 1, preferably for the deposition of multilayer systems with predefinable layer properties on a stationary substrate, containing a recipient with a vacuum generation system, two magnetron sputter sources, at least one substrate holder and a power supply device, wherein - The recipient has a pentagonal cross-section which is symmetrical in the basic geometry, so that four sides are at right angles on at least one adjacent side and three sides form an angle of 135 ° with at least one adjacent side, - a magnetron source with on each of the two large side walls a so-called "hidden" electrode, which is largely protected against coating,

- The three other side walls are each provided with an opening and associated flanges for receiving a substrate holder, such that their centers and the centers of the magnetron sources lie in a plane which forms a pentagonal cross section through the recipient, at least the openings lying opposite the magnetron sources are sealed with vacuum flanges which comprise means for the optional positioning of the substrate holder either directly opposite the center of the respective magnetron sputter sources or offset parallel to the center of the source,

Magnetron sources are connected to one pole of the power supply device in such a way that targets are alternately connected as cathode and anode of the magnetron discharge, and switching between the feeding of unipolar power pulses and bipolar power pulses is possible at any time.

3. Device according to claim 1 or 2, characterized in that in addition, each magnetron source is assigned a shutter, which can preferably be moved in a plane parallel to the respective target surface and in the longitudinal direction of the recipient.

4. Device according to at least one of claims 1 to 3, characterized in that a vacuum flange is arranged in a wall of the recipient, which enables the assembly of means for an in-situ measurement of a plasma parameter or a layer property.

5. Device according to at least one of claims 1 to 4, characterized in that the substrate holder is provided with means which enables rotation of the substrate about its normal to the center.