Patent Application
20200111647
The invention relates to a plasma-treatment device for contactlessly supplying high-frequency voltage to a movable plasma electrode unit, which is suitable for generating a capacitively coupled plasma, in particular in a vacuum. The invention also relates to a method for operating such a plasma-treatment device.
Plasma processes are used in the production of solar cells, in microelectronics or for finishing substrate surfaces (such as glass), for example, in order to deposit or remove layers or particles, to dope layers, for example by means of plasma immersion ion implantation, or to clean or activate the surface of a substrate.
In capacitively coupled plasmas, the substrate to be treated is located in a chamber between two plasma electrodes, high-frequency voltage being supplied to at least one of said plasma electrodes. In this case, a voltage can be applied to the substrate as a result of said substrate being in direct contact with one of the plasma electrodes. This is suitable in particular for plasma-treatment devices in which the substrate(s) is/are arranged in a processing chamber on one of the plasma electrodes such that it/they cannot move. For systems in which the substrates move through a plasma-processing zone, known as in-line systems, it is known to capacitively supply voltage to a substrate; the plasma electrodes themselves, however, being immovable and connected to a voltage supply by means of fixed contacts. Such systems are described in DE 43 01 189 A1 and DE 10 2010 060 762 A1, for example.
In order to increase the throughput of substrates in plasma processing, batch systems in which a plurality of substrates are treated at the same time are used. Here, the surfaces to be processed of the substrates can be arranged next to one another or one on top of the other. In this case, each of the substrates is arranged between the electrodes of a pair of plasma electrodes, which are electrically insulated from one another and are therefore connected to a voltage supply so that a plasma can be capacitively generated between each of said pairs of plasma electrodes. If the substrates are arranged one on top of the other in a plasma electrode unit, up to 200 electrodes, which are arranged in parallel at a typical distance of 3 to 30 mm from one another, are alternately connected to one of at least two voltage supplies, at least one of which is connected to a high-frequency generator of a voltage supply, which is installed outside the plasma-treatment system. One of the at least two voltage supplies can also be earthed.
DE 198 08 206 A1 discloses a plasma-treatment device, in which the plasma electrode unit remains inside the processing chamber, and the plasma electrode unit and the substrate carrier are positioned relative to one another only after the substrate carrier has been introduced into the plasma-treatment chamber such that a substrate is arranged between the electrodes of a pair of plasma electrodes in each case. Voltage can therefore be supplied to the plasma electrode unit by means of an immovably installed, coaxial feedthrough through the wall of the plasma-treatment chamber, for example.
Another batch system, in which the plasma electrode unit is arranged in the substrate carrier (plasma boat) and is inserted into or removed from the processing chamber together with said carrier, is described in DE 10 2008 019 023 A1, for example. As soon as the substrate carrier together with the substrates placed in the plasma electrode unit has been inserted into a plasma-treatment system, an electrical connection is established between the two voltage supplies for the plasma electrode unit and the high-frequency generator.
In the substrate carrier described in DE 10 2008 019 023 A1, the electrical connection is established by means of plug and socket connections, the plugs being inserted from below into the sockets located on the substrate carrier by means of an adjustment device as soon as the substrate carrier is in the intended position in the plasma-treatment system. In order to produce the electrical ohmic contact, typical contact materials are used provided they can be used in the processing environment of the plasma process, in particular even at temperatures between 200 and 500° C. Graphite contact pairs have proven effective, for example.
Contacts of this type and other mechanical contacts, in which a direct mechanical connection and electrical ohmic contact is established between a contact point located on a movable substrate carrier and a contact point installed in the processing chamber, have a typical switching life in the range of 104 switching cycles and therefore have to be serviced or replaced very frequently, for example after just 3 weeks, in the case of short treatment times of the substrate inside the processing chamber. When high-frequency voltages or currents (e.g. 13.56 MHz) are transmitted, the mechanical switching contacts are placed under an even greater amount of stress, thus reducing the service life even more. Furthermore, it is technically more complex to produce mechanical contacts for transmitting high-frequency voltages than for transmitting low-frequency voltages.
The invention relates to a plasma-treatment device, in which a plasma electrode unit can be inserted into and removed from a processing chamber, and in which high-frequency power generated by a generator is transmitted to the plasma electrode unit by means of one or more electromagnetic fields and without an electrical ohmic contact. For this purpose, the plasma-treatment device comprises a transmission apparatus, which contains a primary coupling part, which is arranged inside the processing chamber and can generate an electromagnetic field. The plasma electrode unit contains a secondary coupling part, which is rigidly connected to the plasma electrode unit and is suitable for receiving the electromagnetic field and converting it into alternating electrical power. Furthermore, a method for operating such a plasma-treatment device is provided.
Therefore, the object of the invention is to provide a plasma-treatment device, in which a plasma electrode unit can be inserted into and removed from the plasma-treatment device, and in which high-frequency voltage is supplied to the plasma electrode unit such that the disadvantages of the prior art are prevented or reduced.
The object is achieved by a plasma-treatment device according to claim 1 and by a method for operating such a plasma-treatment device according to claim 14. Preferred embodiments can be found in the dependent claims.
The plasma-treatment device according to the invention comprises a processing chamber, a plasma electrode unit and a transmission apparatus. The plasma electrode unit consists of at least one pair of plasma electrodes made up of a first plasma electrode and a second plasma electrode, which are arranged in parallel, are opposite one another and are electrically insulated from one another. In this case, a “plasma electrode unit” is understood to mean any arrangement of plasma electrode pairs, in which all the first plasma electrodes of the pairs of plasma electrodes are connected to one another so as to conduct electricity by means of ohmic contact and all the second plasma electrodes of the pairs of plasma electrodes are connected to one another so as to conduct electricity by means of ohmic contact in each case. The plasma electrode unit is suitable for being inserted into and removed from the processing chamber, the plasma electrode unit preferably being inserted, removed and moved as a whole. The plasma electrode unit can, in this case, be part of a substrate carrier, for example, so that one or more substrates, each of which is arranged between the plasma electrodes of a pair of plasma electrodes, can be treated by means of a plasma that is generated and maintained in the processing chamber between the plasma electrodes of the pair of plasma electrodes. In this case, “treatment” is understood to mean the application or generation of layers to or on a surface of the substrate, the removal of a layer or of particles from a surface of the substrate, the doping of layers or the cleaning or activation of a surface of the substrate. The electrical power required for generating and/or maintaining the plasma is supplied to the plasma electrodes of the plasma electrode unit from a generator, in particular a high-frequency generator, arranged outside the plasma-treatment device by means of the transmission apparatus when the plasma electrode unit is in a treatment position in the processing chamber. In this case, at least a part of the transmission apparatus is arranged in the processing chamber. Some parts of the transmission unit, such as devices for adapting high-frequency power to the conditions prevailing in the plasma-treatment device, for example pressure, temperature and gas composition, which devices are usually referred to as a matchbox, are preferably located outside the processing chamber.
The plasma-treatment device according to the invention is characterised in that the transmission apparatus contains a primary coupling part arranged inside the processing chamber, and the plasma electrode unit contains a secondary coupling part, which is rigidly connected to the plasma electrode unit. In this case, the primary coupling part and the secondary coupling part are each arranged so as to be suitable for transmitting high-frequency power supplied by the generator to the plasma electrode unit, preferably to each plasma electrode of the plasma electrode unit, by means of electromagnetic fields and without an electrical ohmic contact. In other words, the high-frequency power is contactlessly transmitted to the plasma electrode unit by the transmission apparatus, with “contactless” being understood to mean “without direct, electrical ohmic contact”.
Therefore, the at least one ohmic contact point between the transmission apparatus and the plasma electrode unit required in the prior art is omitted, thus largely avoiding wear of the contact as a result of mechanical abrasion or the formation of arcs, etc. As a result of the contactless transmission, according to the invention, of high-frequency power by means of electromagnetic fields, the possible physical distance between the primary coupling part and the secondary coupling part can lead to virtually wear-free power transmission, thus increasing the service life of the plasma-treatment device and therefore reducing servicing costs.
Transmitting power contactlessly as per the invention is advantageous in particular when transmitting high-frequency powers in the range from 10 kHz to 100 MHz, preferably for frequencies above 1 MHz. Such high-frequency powers can only be poorly transmitted by ohmic contacts. As a result, plasma processes that require a high excitation frequency for generating and maintaining the plasma, such as the deposition of amorphous silicon, can also be carried out in the plasma-treatment device according to the invention.
The primary coupling part and the secondary coupling part contain inductive or capacitive elements for generating an electromagnetic field or for converting said field into alternating electrical power. These inductive and capacitive elements can be integrated in the matchbox of the transmission apparatus or in the electric circuit of the plasma electrode unit, respectively, such that the active power only drops to a minimal extent at said elements, and maximum active power is therefore available for generating and maintaining a plasma between the plasma electrodes of a pair of plasma electrodes of the plasma electrode unit.
The plasma electrodes of the plasma electrode unit are preferably designed so as to be arranged in the plasma-treatment device in a manner insulated against earth potential when the plasma electrode unit is in a treatment position. Furthermore, the primary coupling part and the secondary coupling part are formed so as to be suitable for symmetrically supplying the high-frequency power to plasma electrodes of the plasma electrode unit that are assigned to one another, i.e. to the plasma electrodes of a specific pair of plasma electrodes, with respect to earth potential. Therefore, high-frequency voltages offset by 180° are fed into the different plasma electrodes of the specific pair of plasma electrodes. As a result, the high-frequency voltage applied between the plasma electrodes is twice as high as that fed in in each case, so that the size of the high-frequency voltage fed in in each case can be reduced, in particular approximately halved, with respect to the voltage required for generating and maintaining the plasma. Therefore, only high-frequency voltages that are measured with respect to earth and are comparatively low are applied to the elements of the primary and of the secondary coupling part, to the individual plasma electrodes and to the supply lines between the secondary coupling part and the plasma electrodes, as a result of which parasitic plasmas are largely suppressed, even without the arrangement of insulating or conductive shields. Therefore, the structure of the plasma electrode unit and of the transmission apparatus or the entire plasma-treatment device can be simplified, thus saving costs.
When using inductive elements in the primary and secondary coupling part, high-frequency generators and elements connected to said generators that are suitable for generating an asymmetrical high-frequency voltage can also be used, since the inductive elements generate symmetrical voltages in the secondary coupling part from an asymmetrical voltage provided at the primary coupling part. This has advantages over the use of generators and elements connected thereto, which would be required for generating a symmetrical high-frequency voltage, with regards to costs.
The plasma-treatment device preferably also comprises an adjustment unit, which is suitable for moving the primary coupling part towards or away from the secondary coupling part when the plasma electrode unit is in a treatment position in the plasma-treatment device. The distance between the primary coupling part and the secondary coupling part can therefore be adjusted in each case such that a large distance is set so that the plasma electrode unit can move without damaging the coupling parts during the movement of the plasma electrode unit, whereas the distance in the treatment position is reduced in accordance with the conditions required for transmitting the high-frequency power. When using inductive elements in the coupling parts, i.e. a primary inductor in the primary coupling part and a secondary inductor in the secondary coupling part, the distance in the treatment position is between 3% and 10% of the diameter of the inductors in flat inductors, and between 50% and 100% of the diameter of the inductors in toroidal inductors or cylindrical inductors. When using capacitive elements in the coupling parts, in the treatment position, a distance of 0 (zero) can be set between the primary and the secondary coupling part, or a larger distance in the range from 0.1 to 10 mm can be set. In this case, the adjustment unit can move the primary coupling part by between 5 and 20 mm, for example, preferably by more than 10 mm. In this case, the adjustment unit can be provided with known means, for example with mechanical, pneumatic, hydraulic or electromagnetic drive elements.
In a first embodiment, the primary coupling part comprises at least one primary inductor and the secondary coupling part comprises at least one secondary inductor, each secondary inductor being assigned to a primary inductor. In each case, one end of the secondary inductor is connected to a first plasma electrode of a pair of plasma electrodes so as to conduct electricity, while the other end of the secondary inductor is connected to a second plasma electrode of said pair of plasma electrodes so as to conduct electricity. The at least one primary inductor is suitable for generating an electromagnetic field by means of the high-frequency power supplied by the high-frequency generator, while the at least one secondary inductor is suitable for absorbing the electromagnetic field generated by the at least one primary inductor and generating a high-frequency power which corresponds to the alternating power provided at the primary inductor. The inductors have between 1 and 50 turns, preferably between 3 and 20 turns in this case, the optimum number of turns that can be used reducing with the frequency for high-frequency-related reasons. Typical inductive coupling parts are therefore suitable in particular for transmitting high-frequency powers having a frequency of below 20 MHz, in particular below 10 MHz.
At least one of the at least one primary inductor and at least one of the at least one secondary inductor assigned to said primary inductor are preferably formed as flat inductors. Flat inductors are inductors in which a conductor is formed as a spiral or a meander, with all conductor portions (turns) being located in one plane. The planes of the primary inductor and of the at least one secondary inductor are parallel to one another, the central point of the primary inductor and of the at least one secondary inductor lying on one axis. The design of the primary inductor and of the at least one secondary inductor can either be the same or different. The diameter of the inductors or the lateral dimension (edge length) thereof for a square design is typically in the range from 50 to 250 mm. The inductors can be made of a tubular material or a flat material. For example, a copper tube having a diameter in the range from 4 to 12 mm and a material thickness of 1 to 2 mm, which preferably comprises a silver layer on the surface, can be used as the tubular material, in particular for the primary inductor. A strip material having a thickness of 0.25 to 2 mm and a width of 5 to 50 mm made of copper or aluminium, which advantageously also comprises a silver layer on the surface, can be used as the flat material, in particular for the primary inductor, for example.
Alternatively, at least one of the at least one primary inductor and at least one of the at least one secondary inductor assigned to said primary inductor are formed as cylindrical inductors, in which the turns of the inductor lie one on top of the other and not on one plane. Cylindrical inductors are typically made of tubular material, as already described with reference to the flat inductors. The inductors preferably have a diameter in the range from 30 to 200 mm, the primary inductor and the at least one secondary inductor advantageously having the same diameter. The primary inductor and the at least one secondary inductor can either have the same number of turns or a different number of turns. The primary inductor and the at least one secondary inductor have the same central axis in this case.
In both embodiments, the primary inductor can be cooled using simple means, for example by means of cooling the inside of the inductor with a fluid, e.g. water, when using a tubular material. This is required in particular when transmitting high-frequency powers of more than 1 kW. In contrast, the secondary inductor can only be cooled with difficulty, and therefore the at least one secondary inductor consists of a temperature-stable material suitable for high frequencies. For temperature ranges of up to 250° C., silver-plated copper or stainless steel inductors can be used, whereas inductors made of highly conductive and polished thin graphite, preferably also having a silver coating, are used for temperatures of up to 500° C. At high frequencies, the high-frequency current predominantly flows on the surface of the inductor material (skin effect), and therefore even inductors made of an insulating material that have a thin, electrically conductive surface coating, for example of graphite, silver, aluminium or copper, can be used.
In a second embodiment, the primary coupling part comprises at least two primary electrodes and the secondary coupling part comprises at least two secondary electrodes, each secondary electrode being assigned to a specific primary electrode and being suitable for forming a capacitor together therewith. The primary electrode of a first capacitor is connected to one connection (terminal) of the high-frequency generator so as to conduct electricity, while the primary electrode of a second capacitor is connected to the other connection (terminal) of the high-frequency generator so as to conduct electricity. The secondary electrode of the first capacitor is connected to a first plasma electrode of a specific pair of plasma electrodes so as to conduct electricity, while the secondary electrode of the second capacitor is connected to a second plasma electrode of the specific pair or plasma electrodes so as to conduct electricity. A plurality of secondary electrodes that differ in terms of the surface area or the material of the dielectric, for example, can also be assigned to one primary electrode. Therefore, the plurality of secondary electrodes can absorb different electrical powers and supply them to different regions of the plasma electrode unit in each case.
The primary electrodes of the primary coupling part and the secondary electrodes of the secondary coupling part therefore form at least two separable capacitors, which are suitable for supplying the plasma electrodes of the plasma electrode unit with a symmetrical high-frequency voltage. Typical capacitances of the coupling capacitors are in the range between 0.5 and 2 nF. Since considerably less voltage is intended to drop at the coupling capacitors than the maintaining voltage of the plasma, the coupling capacitors each have a capacitance that is greater than or equal to a minimum capacitance that depends on the requirements of the plasma-treatment device. Therefore, the minimum capacitance for an alternating power having a frequency of 13.56 MHz is 1 nF, for example. Since the voltage drop at the capacitors decreases as the frequency increases, capacitive coupling parts are suitable in particular for transmitting high-frequency powers having a frequency in the range from 10 to 100 MHz, in particular for frequencies of more than 20 MHz.
Any dielectric can be provided between the primary electrode and the secondary electrode of a coupling capacitor, for example the atmosphere prevailing in the processing chamber. In this case, the primary electrode and the secondary electrode are spaced apart from one another during transmission of the alternating power. However, at least one of the primary electrode or the secondary electrode of a specific capacitor preferably comprises an additional dielectric. This means: an additional dielectric is arranged on the primary electrode or on the secondary electrode or on the primary electrode and the secondary electrode. The dielectric is preferably between 0.25 and 1 mm thick and consists of a material having a relative permittivity of more than 5. This can be aluminium oxide having a relative permittivity of 8 to 9, for example. The primary coupling part is preferably moved towards the secondary coupling part by means of the adjustment unit when the plasma electrode unit is in a treatment position in the processing chamber such that the dielectric is then in mechanical contact with the respectively assigned secondary electrode or primary electrode of the specific capacitor. Once the plasma-treatment process has finished, the primary coupling part is re-removed from the secondary coupling part, and the coupling capacitors are therefore separated such that the plasma electrode unit can be re-removed from the plasma-treatment device.
The primary electrode and the secondary electrode of at least one specific capacitor particularly preferably each have a non-planar surface, which is opposite the other electrode in each case and corresponds to the shape of the non-planar surface of the other electrode in each case. In this case, the surfaces are intended to be shaped such that the primary electrode and the secondary electrode engage in one another without the formation of a parasitic gap when the primary electrode and the secondary electrode are brought into contact with one another. Furthermore, the shape of said surface has to be suitable for the primary electrode and the secondary electrode to be released from one another again, both easily and without damaging the electrodes. The shape of the surfaces is advantageously selected such that the primary electrode and the secondary electrode align themselves relative to one another when the primary electrode and the secondary electrode are brought into contact with one another.
The embodiments described thus far of the primary and of the secondary coupling part are particularly suitable for transmitting high-frequency power to a plasma electrode unit, which is arranged in the processing chamber such that it is stationary and cannot move whilst power is transmitted. For this purpose, the primary coupling part or the secondary coupling part preferably comprises an alignment device, by means of which the inductive or capacitive elements of the primary coupling part and of the secondary coupling part can be positioned relative to one another in the treatment position in a direction that is perpendicular to the distance between the primary coupling part and the secondary coupling part so as to ensure that a desired, predetermined amount of high-frequency power is transmitted.
In another embodiment of the capacitive transmission of power, the primary electrode and the secondary electrode of at least one specific capacitor each comprise at least two plate-shaped regions, which each extend from a common connecting region towards the other electrode in each case, and extend in a direction in which the plasma electrode unit is inserted into and removed from the plasma-treatment device. The number of plate-shaped regions of the primary electrode and of the secondary electrode of a specific capacitor can be the same or can differ by one. The primary electrode and the secondary electrode are each formed as a comb, the plate-shape regions forming the teeth of the particular electrode comb and reaching into the gaps between the teeth of the other electrode comb. In this case, the plate-shaped regions of the primary electrode and of the secondary electrode are opposite one another, at least in part, when the plasma electrode unit is in a treatment position in the plasma-treatment device. This means that the plate-shaped regions of the primary electrode and of the secondary electrode are opposite one another in a direction extending perpendicularly to the plane of extension of the plate-shaped regions. In this direction, the plate-shaped regions are spaced apart by between 0.1 and 10 mm, the atmosphere prevailing in the processing chamber being located between the regions. The distance is intended to be the perfect balance between a large coupling capacitance, associated with a small distance, and the prevention of a parasitic plasma between the electrodes, which is associated with a large distance. By means of this design of the primary and secondary electrodes, it is possible to particularly expediently implement capacitive coupling in order to transmit the high-frequency power without using an adjustment unit and without having to position the secondary coupling part of the plasma electrode unit with respect to the primary coupling part of the transmission apparatus with a high degree of accuracy. In a particular embodiment, the plasma electrode unit can even move during transmission of the high-frequency power, and therefore the transmission of power is also suitable for plasma-treatment devices in which the plasma electrode unit is continuously moved, known as continuous systems. In a particularly preferred embodiment, the plasma electrode unit moves linearly into a direction along which the plasma electrode unit is moved into the plasma-treatment device and moved out of it,
In all the embodiments, the inductive or capacitive elements in both the primary coupling part and in the secondary coupling part, i.e. the inductors or capacitor electrodes, can be shielded by means of insulating or conductive elements in order to prevent the formation of parasitic plasmas.
According to a particular embodiment, the plasma-treatment device contains a plurality of plasma electrode units and a plurality of transmission apparatuses. In this case, each plasma electrode unit is assigned to a specific transmission apparatus and each transmission apparatus comprises a primary coupling part and each plasma electrode unit comprises a secondary coupling part, which are suitable for transmitting high-frequency electrical power to the particular plasma electrode unit by means of electromagnetic fields and without being in electrical ohmic contact with one another. In other words: the primary and secondary coupling parts are formed as described above.
The method according to the invention for operating the plasma-treatment device according to the invention comprises the steps of inserting the plasma electrode unit into the processing chamber, generating an electromagnetic field in the primary coupling part and transmitting the high-frequency electrical power to the secondary coupling part, disconnecting the primary coupling part from the high-frequency electrical power supplied by the high-frequency generator, and removing the plasma electrode unit from the processing chamber. The method begins with inserting the plasma electrode unit into the processing chamber along a first direction until the plasma electrode unit is in a treatment position in the processing chamber and the primary coupling part and the secondary coupling part are opposite one another, at least in part. Once the plasma electrode unit has been inserted, an electromagnetic field is generated in the primary coupling part by applying a high-frequency electrical power supplied by a generator to the primary coupling part. Said electromagnetic field transmits the high-frequency electrical power to the secondary coupling part, thus generating and maintaining a plasma between the plasma electrodes of a pair of plasma electrodes of the plasma electrode unit. Once an operating aim has been reached in the processing chamber, the primary coupling part is disconnected from the high-frequency electrical power supplied by the generator and the plasma electrode unit is then removed from the processing chamber along the first direction. The method according to the invention is advantageous on account of the contactless and therefore low-wear transmission of high-frequency power from a generator to a plasma electrode unit. The plasma-treatment device can therefore be operated for a longer amount of time than a plasma-treatment device having ohmic contacts before needing to be serviced.
When the plasma electrode unit is inserted, it is preferably moved such that, once it reaches the treatment position, a first distance is provided between the primary coupling part and the secondary coupling part. Following this insertion and before generating the electromagnetic field, the primary coupling part is moved towards the secondary coupling part by means of an adjustment unit until a second distance is formed between the primary coupling part and the secondary coupling part. In this case, the second distance is smaller than the first distance. After the primary coupling part has been disconnected from the alternating electrical power and before removing the plasma electrode unit from the processing chamber, the primary coupling part is moved away from the secondary coupling part by means of the adjustment unit until a third distance is formed between the primary coupling part and the secondary coupling part. In this case, the third distance is larger than the second distance and can preferably be equal to the first distance. The distance between the primary and the secondary coupling part is therefore set by the adjustment unit such that, during the steps of inserting and removing the plasma electrode unit into or from the processing chamber, a large distance is provided that prevents the coupling parts from getting damaged, and, during the step in which the alternating power is transmitted, a smaller distance is provided, which is optimal for transmitting the alternating power.
If the primary coupling part comprises at least one primary inductor and if the secondary coupling part comprises at least one secondary inductor, it is advantageous to cool the primary inductor during the step of generating an electromagnetic field and transmitting the high-frequency power.
The invention will be described in the following in more detail with reference to the drawings, in which:
The plasma electrode unit 20 can preferably only move in the processing chamber 10 in the direction in which it is inserted and removed, but can also move in other directions in the xyz coordinate system or can be rotated about an axis if the corresponding devices for carrying out the movement are provided. In the case shown, the plasma electrode unit 20 comprises five pairs of plasma electrodes, which are formed of three first plasma electrodes 21a to 21c and three second plasma electrodes 22a to 22c. The first plasma electrode 21a and the second plasma electrode 22a thus form a first pair of plasma electrodes, for example, while the second plasma electrode 22a and the first plasma electrode 21b form a second pair of plasma electrodes. All the first plasma electrodes 21a to 21c are connected to one another via a supply line 24 so as to conduct electricity and are supplied with a first electrical voltage. All the second plasma electrodes 22a to 22c are connected to one another via a supply line 25 so as to conduct electricity and are supplied with a second electrical voltage. When the corresponding voltages are applied, a plasma 23 forms between the first plasma electrode and the second plasma electrode of a pair of plasma electrodes, wherein substrates which are arranged between the electrodes (not shown in this case) can be treated by means of the plasma, for example. The plasma electrode unit 20 can comprise any number of pairs of plasma electrodes that is equal to or greater than 1, it also being possible for individual plasma electrodes of specific pairs of plasma electrodes to be supplied with voltages other than the first or the second voltage. The plasma electrodes of the plasma electrode unit 20 can also be arranged vertically, i.e. in the z direction.
The plasma-treatment device 1 further comprises a transmission apparatus 30, which can transmit high-frequency power, which is supplied by a generator 40, to the plasma electrode unit 20 without direct ohmic contact. For this purpose, the transmission apparatus 30 contains a primary coupling part 31, which is arranged inside the processing chamber 10 and can generate an electromagnetic field, by means of which the high-frequency power is transmitted to a secondary coupling part 26 that is part of the plasma electrode unit 20. The secondary coupling part 26 then provides corresponding electrical voltages and electrical powers to the individual plasma electrodes of the pair of plasma electrodes. The transmission apparatus 30 further contains a matchbox 32, by means of which high-frequency power supplied by the generator 40 can be adapted to the conditions inside the processing chamber 10.
In order to be able to adjust the distance between the primary coupling part 31 and the secondary coupling part 26 in accordance with the particular work step, the plasma-treatment device 1 comprises an adjustment unit 50, which is used to move the primary coupling part 31 towards or away from the secondary coupling part 26. In the case shown, this corresponds to a movement of the primary coupling part 31 along the z direction. However, the primary coupling part 31 can alternatively also be moved along the y direction if the primary coupling part 31 and the secondary coupling part 26 are opposite one another in the y direction. In other words: the arrangement shown in
In order to accurately position the primary coupling part 31 and the secondary coupling part 26 in the x-y plane relative to one another, the plasma-treatment device 1 can further comprise an alignment device 60, which can displace the primary coupling part 31 and/or the plasma electrode unit 20 and the secondary coupling part 26 rigidly connected thereto in the x and/or y direction.
A number of examples of materials and dimensions of the flat inductors 33a and 27a and the distance s are given in the following. For example, a flat inductor can be made from tubular material having an external tube diameter of 4 to 12 mm, in which the height h and the width b correspond to the external tube diameter. If the flat inductor is formed from a flat material, the height h is between 0.52 and 2 mm and the width b is between 5 and 20 mm. The diameter or the edge lengths a1 and a2 are typically between 50 and 250 mm and the distance s is between 3% and 10% of the diameter or the longer of the two edge lengths, i.e. lies between 1.5 and 25 mm.
The elements of the two coupling capacitors 70a, 70b, i.e. the primary electrodes 34a and 34b, the secondary electrodes 28a and 28b and the dielectrics 71a and 71b can be the same or different, at least in part, in terms of their dimensions (length, width, thickness) and the material. The dimensions and materials are determined by the capacitance to be achieved by the coupling capacitors 70a, 70b and by the dimensions and conditions (temperature, pressure, gas composition) prevailing in the plasma-treatment device.
The precise design of the primary coupling part and of the secondary coupling part in all the embodiments can be optimally adapted to the conditions in the processing chamber and to the electrical power required for generating and maintaining the plasma between the plasma electrodes of a pair of plasma electrodes. In this case, different embodiments and designs may optionally also be combined.
| Number | Date | Country | Kind |
|---|---|---|---|
| 16170628.8 | May 2016 | EP | regional |
This application is the U.S. national stage of International Application No. PCT/EP2017/061928, filed on 2017 May 18. The international application claims the priority of EP 16170628.8 filed on 2016 May 20; all applications are incorporated by reference herein in their entirety.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2017/061928 | 5/18/2017 | WO | 00 |
