WO2012119700A1 - Device and method for the plasma-assisted treatment of at least two substrates - Google Patents

Abstract

The invention relates to a method and device for the plasma-assisted treatment of at least two substrates (16, 20), comprising: a vacuum chamber (12; 30; 60) in which at least two substrates (16, 20) can be arranged with a predetermined spacing, and in such a manner that the surfaces to be treated of said substrates face each other; and a plasma generation device which comprises at least one excitation coil (22; 32; 40; 50; 56; 62) for the inductive excitation of at least one plasma (80) located between the substrates (16, 20).

Description

 Apparatus and method for plasma enhanced treatment of at least two substrates

Description

The present invention relates to a device and a corresponding method for the simultaneous plasma-assisted treatment of at least two substrates, in particular for coating substrates for the production of semiconductor or photovoltaic components.

Background and state of the art

Devices and methods for plasma assisted processing of substrates, particularly for etching and coating substrate surfaces, are well known in the art. For example, chemical vapor deposition methods, in particular plasma-enhanced chemical vapor deposition methods, so-called PECVD methods, are used to apply coatings as thinly as possible to substrates as uniformly as possible.

In this case, one or more substrates are arranged in a vacuum chamber, into which a reaction gas or a gas mixture adapted to the coating is introduced while maintaining predetermined pressure and temperature ranges, which at least partially passes into a plasma state by supplying electromagnetic energy in the HF range.

In order to excite and maintain a plasma in a plasma or vacuum chamber, a high frequency voltage is typically applied between two electrodes to obtain a plasma excitation. For this purpose, the substrates to be treated or their holding elements intended for this purpose are often

CONFIRMATION COPY switched itself as an electrode. For example, in a parallel plate arrangement, a substrate to be coated is placed directly on or attached to one of the electrodes. The electrode and the substrate are exposed to the plasma treatment in a nearly identical manner. Based on the spatial extent of the generated plasma, the substrate surface to be treated in this way is relatively small.

Further, for example, from JP 03-173124, there is known a vertical-type parallel plate coater in which two thin-film substrate holders are disposed opposite to a conveyor of insulating material. The substrate holders in this case form a double-sided electrode structure, on each of which four individual substrates are arranged opposite one another. Movable electrical conductors are attached to the backs of the two holders, which are connected to an RF power supply. In an opposed pair of electrodes of a parallel plate capacitor array, the RF voltage is usually applied to one of the electrodes. The other RF electrode is grounded. For the electrodes, this means nothing else than that an RF voltage is applied between the electrodes.

In a PECVD coating process, however, the use of substrate holders as excitation electrodes may also be disadvantageous. In this way, the electrodes are exposed to a plasma deposition comparable to the substrate to be coated. After a certain number of coating processes, the electrodes must therefore be replaced or subjected to a corresponding cleaning procedure. Furthermore, in the case of a purely capacitive excitation, the treatable area is limited by the application of the substrates to the electrodes. In particular, however, the achievable treatment times are often quite long due to a comparatively low plasma density during capacitive discharge. The treatment process is thus quite tedious and not cost effective. Furthermore, a plasma treatment chamber is known from US 2009/0004874 A1, in which a pianolar coil extends over the entire interspace between opposing substrates or opposite substrate holders. For this purpose, however, a basic structural adaptation of the housing of the process chamber is required. This accordingly has a slot or shaft-like receptacle, which has opposite dielectric windows as side walls. By means of that receptacle, a sort of subdivision of the process chamber into two different treatment zones is achieved, wherein in each of the treatment zones a gas distribution provided for this purpose is provided for producing two separate plasmas. It may also be disadvantageous if, in addition to the substrates, the dielectric windows are also coated in a plasma coating process. task

The present invention is based on the object of enabling an improved plasma-assisted treatment of substrates, wherein in particular an available plasma source should be used as efficiently as possible and a surface treatment of the substrate which is as homogeneous as possible should be made possible. In addition, the process and cycle times of a plasma-assisted treatment process should be shortened and the spatial extent and the volume of the vacuum chamber should be kept as low as possible. Another goal is to minimize the process gas consumption and to keep the cleaning effort of the vacuum chamber low.

invention

The object underlying the invention is achieved by means of a device for plasma-assisted treatment according to the independent claim 1 and with a corresponding method according to claim 21, wherein advantageous applications are each the subject of dependent claims. The device-technical solution provides for a vacuum chamber in which at least two substrates can be arranged facing each other at a predetermined distance and with their surfaces to be treated facing one another. In this way, at least two oppositely arranged substrates can be treated simultaneously. Furthermore, the device according to the invention has a plasma generating device, which has at least one excitation coil for inductive excitation of at least one plasma located between the substrates.

The excitation coil serves for preferably purely inductive excitation of at least one plasma to be provided between the substrate surfaces to be treated. It goes without saying that the plasma generating device also has suitable supply possibilities for the gases forming the plasma. Corresponding gas inlets must therefore be provided between the opposing substrates.

By means of a preferably purely inductive excitation of the plasma, significantly higher deposition rates can be achieved in a plasma coating process compared to a capacitively based excitation. In particular, in the case of an inductive excitation, the density of the plasma to be generated or maintained can be increased in comparison to a purely capacitive excitation.

By having the plasma between two opposing substrates, a plurality of spatially separated substrates can be simultaneously coated with a single plasma. By limiting the plasma, as it were, from at least two sides by substrate surfaces to be coated or treated, the cleaning effort for the vacuum chamber can also be kept comparatively low. By means of the at least one excitation coil, a single plasma can be generated in this respect, which can directly interact directly with the substrates located opposite and facing each other within the vacuum chamber. Furthermore, it proves to be advantageous that in the case of an inductive excitation of the plasma no electrodes required for plasma formation must be arranged within the vacuum chamber. The substrate holders are so far not part of the plasma source itself and thus can be used completely independent of a plasma generation.

According to a preferred embodiment, the excitation coil is located with respect to its circumferential direction, i. with its outer periphery, outside the gap formed by the opposing substrates or substrate holders. By "gap" is meant that volume which, based on a surface normal of the substrates or substrate holders, is bounded on one side by the mutually opposite substrate or substrate holder surfaces and on the other hand by the substrate edges or substrate holder edges lying perpendicular to the surface normal in the plane. Thus, the at least one excitation coil extends e.g. in the plane perpendicular to the surface normal of the substrates or the substrate holder, outside an imaginary projection surface of the substrates or the substrate holder. Consequently, the at least one excitation coil is located outside of all the straight connecting lines that are conceivable between the opposing substrates.

Due to the displacement of the coil outside the substrate interstice, the intermediate space formed between the substrates can be made substantially barrier-free within the vacuum chamber and the substrates can be arranged in a particularly space-saving manner directly adjacent to a single, jointly usable plasma to be formed between them. The treatment volume to be provided in the vacuum chamber can thus advantageously be reduced, as a result of which set-up and pump-down times for providing the plasma conditions can be shortened. Also, by means of the at least one lying outside the substrate space Excitation coil, the vacuum chamber have a relatively simple cubic geometry with substantially planar trained circumferentially arranged side walls and with a bottom and a top. In addition to a substantially cubic rectangular geometry, however, the vacuum chamber can also have round or oval upper and lower sides with a circumferential side wall structure corresponding to the curvature. According to a further preferred embodiment, provision is made in particular for the plasma generating device to be designed for coupling electromagnetic energy into the plasma or into the gas mixture forming the plasma, so that it can be operated in H mode or burn in H mode.

Electromagnetic radiation is known to always have an E-field and a B-field component, so that inductive coupled plasma excitation both inductive and capacitive energy transfer mechanisms, known as "mode" for a capacitive energy transfer mechanism and as "H-mode" for a pure A characteristic feature of inductive excitation is that H-mode predominates in the plasma, or at least that there is a noticeable amount of H-mode, the H-mode component of the inductive excitation being at least 10%, 30 %, 50%, 70% or 90% of the inductive energy transfer to the plasma For a closer discussion and the H-mode, the dissertation "Diagnostics and Modeling of inductively coupled radio frequency discharge in hydrogen ", Faculty of Physics and Astronomy, Ruhr-University Bochum 2004,", pages 14 ff The plasma densities obtainable by means of the H-mode operation can be an order of magnitude higher than comparable capacitively excitable plasmas. Preferably, the plasma generating device, in particular the at least one excitation coil in a parameter range to operate, in which the plasma excitation occurs almost exclusively in the H-mode regime.

According to a further preferred embodiment, the at least two substrates can be arranged spaced apart in the direction of their surface normals in the vacuum chamber. The at least one excitation coil of the plasma generating device preferably extends between the substrates in relation to the surface normal. This means that the excitation coil is arranged approximately in the region of the intermediate space formed by the substrates. However, in particular in the circumferential direction, it can nevertheless extend outside of that intermediate space and thus also outside the substrates in order to be able to form the largest possible plasma region corresponding to the substrate surface. Furthermore, it is conceivable that the at least one coil surrounds the substrates, respectively the substrate holders, with their outer circumference aligned substantially parallel to the substrate plane, but is arranged outside the substrate interstice in the direction of the surface normals of at least one substrate.

It is further provided that the at least one excitation coil extends outside or inside or between the substrate planes arranged substantially overlapping one another. The excitation coil can always be located outside the substrate edges. In an arrangement outside the substrate plane in this case the plane of the coil with respect to the surface normal of the substrate plane offset or spaced preferably arranged parallel to the substrate plane arranged. In particular, in an arrangement of the excitation coil lying outside the substrate plane, a largely homogeneous and dense plasma can be generated in the space between the substrates, since spatial inhomogeneities in the region of the magnetic field edges can lie outside the substrate region.

It also proves to be advantageous if the excitation coil substantially encloses an intermediate space formed between the substrates in the circumferential direction. It is provided in particular that the at least an excitation coil has only a single turn in order to minimize the inductance and the electrical power loss of the coil. The coil itself can have an approximately closed structure. However, to form a single turn, the electrical connections for the coil are to be formed separately from one another.

A single coil winding is therefore not completely closed form but requires a kind of gap geometry, at least in their connection area. The coil itself can have a wide variety of geometries. It may be formed as a nearly closed circle but also in a modification thereof have a rectangular or square shape, which corresponds for example to the shape of the substrates or a substrate arrangement. In particular, the geometric configuration of the excitation coil of the geometric configuration and / or the geometric arrangement can correspond to at least one substrate that can be fastened to a substrate holder. For example, e.g. It is conceivable, in accordance with the substrate or substrate holder geometry, to realize an equidistant arrangement between the excitation coil and the substrate edge in the projection of the substrate plane, so that a plasma which is as homogeneous as possible over the substrate surface can be produced over the substrate surface.

According to a further preferred embodiment, the at least one excitation coil is arranged outside the vacuum chamber. This has the advantage that the volume of the vacuum chamber can be correspondingly reduced and that the coil, in contrast to arranged in the chamber excitation electrodes, for example, after a coating process no cleaning procedure must be subjected. In addition, the arrangement of the excitation coil lying outside the chamber allows its largely flexible geometric configuration to form required magnetic fields and / or plasmas. It proves to be further advantageous according to a further preferred embodiment, when one of the outer excitation coil facing surface portion of the vacuum chamber is formed induction permeable so to speak. This surface portion of the vacuum chamber should be substantially permeable to the magnetic portion of electromagnetic radiation. This can be realized, for example, by forming a dielectric window in the chamber wall. Advantageously, the chamber wall is at least partially made of a dielectric material, such as glass or a ceramic material. In addition thereto, slotted metal sheets may also be used which function as a so-called Faraday shield and form a shield permeable at least to the inductive portion of the electromagnetic radiation.

In contrast, however, it is also conceivable to arrange the at least one excitation coil within the vacuum chamber. However, the coil may be electrically isolated to avoid high local electric field strengths. Under certain circumstances, these would favor the capacitive discharge and counteract the desired operation of the plasma in H-mode. However, the electrical insulation is not mandatory. As long as the coil is arranged at a distance of typically 10 mm with respect to the chamber wall or other electrically conductive components in the vacuum chamber can be dispensed with a separate coil insulation. Further, in an arrangement within the vacuum chamber, a spiral coil arrangement may be provided. That is, the coil has a plurality of spirals lying in a plane, wherein the plane of the windings is preferably aligned parallel to the substrate plane. In this case, the spiral plane of the coil can, for example, be arranged centrally between the opposing substrates in order to create the same boundary conditions as possible for both substrates. Instead of a central arrangement located between opposing substrates, the at least one excitation coil can also be arranged outside the opposing substrates, ie facing away from the substrate back space substrate backside.

In the present case, a spiral-like coil can also be used to denote coils which contain a plurality of, e.g. have up to four in a common plane nested spirally formed individual coils. As mentioned in the aforementioned dissertation by Victor Kadetov, thus, the electrical resistance of the coil can be reduced, but at the same time the flux density of the magnetic field can be increased in an advantageous manner.

Alternatively, it is conceivable to use at least two spiral-shaped flat coils which are each arranged on a side of the substrate holder remote from the substrate interstice, as it were on the rear side of the substrate holder. In the case of such a coil arrangement lying outside the substrate interstice, the interspace between the substrates can be formed largely free of coils. In a further development of this, it is also conceivable, for example, to arrange three such spiral-shaped flat coils parallel to one another within the vacuum chamber, wherein each of the substrates or each of the substrate holders lies between two flat coils. According to a further preferred embodiment, the turns of the spiral-shaped excitation coils are either individually or bundled electrically insulated from the plasma to be generated. For example, to form the excitation coil, an electrically insulated coil core can be spirally wound into a flat coil. Alternatively, a coil arrangement can be provided, in which a coil core, which is not insulated per se, is spirally wound and subsequently embedded in an electrically insulating medium. In this case, it would be conceivable to arrange the flat coil between two insulating layers or to provide it beyond at least one insulating layer so as to obtain bundled electrical insulation with respect to the plasma. Regardless of whether the coil has an annular geometry with a single or multiple windings or whether it is designed as a flat coil, the at least one excitation coil can be aligned in particular parallel to the at least two opposing substrates or imaginary substrate planes formed therefrom. Related to the distance between the opposing substrates, an approximately central arrangement of the at least one coil but also an arrangement offset therefrom in the direction of the surface normals of the substrates is conceivable, wherein the at least one coil projects the substrates substantially in projection along the surface normals of the substrates Surrounds circumferential direction and thus lies outside of a projection surface of the substrates or outside of the space formed by the substrates.

According to a further preferred embodiment, the at least one excitation coil is arranged relative to a surface normal of at least one substrate outside the gap formed by the opposing substrates. Here, the at least one excitation coil is located not only in the circumferential direction but also perpendicular thereto, namely with respect to the surface normal of at least one substrate, outside of the substrate interstice. In this case, the excitation coil can typically be arranged facing a substrate rear side facing away from the substrate space.

In this case, it is also possible to provide a plurality of exciter coils arranged approximately offset along the surface normal of the substrates and aligned parallel to one another. These can lie, for example, approximately at the substrate level, between and also outside the substrate planes and outside the substrate edges, and preferably substantially surround the substrates in the circumferential direction. In this case, the excitation coils can be arranged both in the circumferential direction and perpendicular to it, ie in the direction of the surface normal of the substrates or of the substrate holder both inside and outside the vacuum chamber. Also, at least one of the excitation coils can be quasi integrated into the wall of the vacuum chamber. In particular, it is conceivable to arrange at least one excitation coil approximately in the transition region between a lateral chamber wall and a chamber bottom and / or chamber cover. According to a further preferred embodiment and independently of the coil geometry, it is further provided according to the invention that the substrate holders provided for holding the substrates have no function influencing the maintenance of the plasma. In particular, the substrate holders are not formed here as electrodes. Nevertheless, they can be subjected to electrical voltage in order, for example, to exert a mechanical holding force on the substrates and / or to be able to influence ion bombardment of the substrates in a targeted manner.

Furthermore, according to a further preferred embodiment of the invention, it is provided that the plasma generation device is designed to generate a plasma by utilizing the electron cyclotron wave resonance effect (ECWR). The ECWR effect can be used to produce a further increased plasma density, which is advantageous for reducing treatment and cycle times.

In this case, according to a further preferred embodiment, the plasma generating device is designed to form a further, static and perpendicular to the axis of the excitation coil oriented magnetic field. The static, as homogeneous as possible magnetic field to be superimposed on the actual excitation coils, which serves to exploit the ECWR effect, can be generated, for example, with a pair of Helmholtz coils. According to a further preferred aspect, it proves to be advantageous if the substrates are treatable in a vertical orientation, with a substantially horizontally oriented surface normal within the vacuum chamber. In particular, in a coating process, any gravitational influences can be largely equalized in this way. Also, a possible disturbing influence of foreign particles in the chamber can be reduced. In particular, substantially identical conditions can be created for the two opposing and vertically oriented substrates, so that, if possible, the at least two oppositely arranged substrates can be coated in the same manner, treated identically, in particular identically. Depending on the size of the substrate and its thickness, a possible bending of the substrates can be avoided in the case of a vertical or approximately vertical arrangement.

In particular, it is provided according to a further preferred embodiment that all provided for plasma generation components of the plasma treatment apparatus for symmetrical as possible expansion and / or symmetrical positioning of the plasma are designed with respect to the opposite substrates. Thus, the plasma can be formed substantially symmetrically between the substrates in terms of its spatial extent and / or in terms of positioning and alignment. In the case of a coating process, it is thus possible to achieve virtually identical plasma deposition rates and correspondingly identical coating thicknesses on the substrates.

According to a further development, it is also conceivable that the plasma chamber can be divided into at least two partial chambers which each have a partial plasma and in each case receive at least one substrate. The two partial plasmas can be generated by means of a common plasma generating device. In particular, by purely inductive excitation of the plasma or a plurality of plasmas, a plurality of plasmas can be stimulated and operated simultaneously with a single plasma source. This allows, for example, too an asymmetric treatment, in particular asymmetrical coating of the sub-chambers each arranged separately, facing each other oriented substrates. A single plasma source can thus be used particularly efficiently.

In a further independent aspect, the invention further relates to a method for plasma-assisted treatment of at least two substrates, wherein in a first step at least two substrates are arranged at a predetermined distance from each other in a vacuum chamber. In this case, the substrates are to be aligned with their surfaces to be treated facing each other. The opposite substrates, or the substrate holder are hereby preferably arranged parallel to one another and in the direction of their surface normal to each other surface covering. In a second step, a plasma for surface treatment of the substrates is then produced and maintained in an inductive manner. This is done by means of at least one excitation coil having plasma generating means such that the plasma is formed between the at least two substrates. The substrates or the substrates receiving holders are preferably arranged in a mutually overlapping but spaced apart in the direction of their surface normal configuration, so that as possible identical conditions can be created for the substrates to be treated with respect to the plasma generation.

It proves to be particularly advantageous if the at least two substrates are arranged in vertical alignment in the vacuum chamber. As already stated for the device described above, any gravitational influences which could otherwise lead to asymmetries in the plasma treatment can be largely prevented in this way. Furthermore, the influence of particles or other residues present in the vacuum chamber can be reduced compared to a horizontal or horizontal orientation of the substrates. Also, the plasma chamber can be divided into at least two, each having a partial plasma and receiving at least one substrate sub-chambers. The at least two partial plasmas are then generated or maintained by means of a common plasma generating device. The excitation coil provided for this purpose is preferably arranged outside the plasma chamber.

The method for plasma-assisted treatment is preferably designed in such a way that the substrates arranged opposite one another in the plasma chamber are treated essentially identically. In particular, when the method is designed as a coating process, it is provided that the substrates arranged opposite one another in the vacuum chamber are coated with essentially identical plasma deposition rates.

In general, it should be noted here that said method can be carried out with the described device for plasma-assisted treatment of the at least two substrates. Features explained in connection with the device are equally valid for the treatment method and vice versa. Also, the device is not only suitable for coating substrates but also basically equally for plasma-assisted etching.

Brief description of the figures

Other objects, features and advantageous applications of the present invention will become apparent from the following description of exemplary embodiments with reference to the drawings. Here are all depicted in the figures as well as in the text solely borrowed features described in isolation as well as in any meaningful combination with each other the subject of the invention. Show it: a device according to the invention for plasma-assisted treatment of at least two oppositely arranged substrates in cross-section, a longitudinal section through the device of Figure 1 at the level of its plane of symmetry, another, ring-shaped plasma chamber in longitudinal section, a regional representation of the plasma chamber with a two turns excitation coil, the plasma chamber with an internal excitation coil, a cross-section only partially shown by a vacuum chamber with a arranged between the substrates spiral flat coil, a further embodiment of a centrally disposed, sandwiched between two insulating layers flat coil, two outside the substrate space but within the plasma chamber lying spiral excitation coils, an embodiment with two parallel to each other, arranged in the space between the substrates flat coils, another embodiment with two Außerh and a further embodiment having an excitation coil arranged outside and two excitation coils arranged inside the vacuum chamber, FIG. 12 shows an embodiment with excitation coils integrated in the chamber wall, and FIG. 13 shows a further embodiment with a total of three excitation coils arranged offset to one another in the direction of the surface normal of the substrates.

Detailed description

In FIGS. 1 and 2, the device according to the invention for the plasma-assisted treatment of at least two substrates 16, 20 arranged opposite to one another is shown in cross section as well as in plan view from above. The vacuum or plasma treatment device 10 shown here only schematically has a vacuum chamber 12, in which two substrate holders 14, 18 arranged at a distance from one another are arranged. On each of the two substrate holders 14, 18, as shown in Fig. 2, four individual substrates 16, 20 are detachably arranged.

The substrates 16, 20 are in this case arranged facing each other in a vertical distance in FIG. 1 in the direction of their surface normal almost overlapping. The vacuum chamber 10 in the present case has an approximately square basic geometry. It is further provided with an excitation coil 22, which is located outside of the vacuum chamber 12, relative to the vertical, ie to the surface normal of the substrates 16, 20, approximately centrally between the spaced-apart substrates 16, 20.

The outer wall of the vacuum chamber 12, the approximately circumferentially formed coil 22 facing an induction-permeable portion 24. This may be formed, for example, by a dielectric material, such as glass or a ceramic material. In addition, it is conceivable to provide a slotted or perforated metal sheet in the wall region 24, which acts as a kind of Faraday shield. In this way, at least the B field component of the RF field which can be generated by the coil 22 is coupled into the vacuum chamber 12 and in particular into the intermediate space between the substrates 16, 20. The inductive coupling of the RF field of the coil 22 and the plasma 80 to be formed between the substrates 16, 20 takes place in the so-called H mode. The operating parameters for the treatment apparatus 10, in particular with regard to the process gases to be used, process temperatures, process pressures and the electrical control of the excitation coil 22 are coordinated such that an energy coupling between the electromagnetic field generated by the coil 22 and the plasma 80 in the so-called H-mode takes place.

With the opposite, sandwich-like arrangement of two opposing substrates 16, 20, the plasma 80 formed in the vacuum chamber 12 can be used much more efficiently, for example, for etching the substrate surfaces or for coating them. Furthermore, by the inductive coupling of the coil 22 with the plasma 80 on the one hand, a comparatively high plasma density associated with correspondingly high deposition rates and associated short process and cycle times can be achieved.

On the other hand, the excitation coil 22 can be positioned outside the chamber 12, so that the chamber 12 can be made smaller overall and accordingly lower demands are placed on the chamber, for instance with regard to vacuum generation.

The geometry of the vacuum chamber 12 shown in FIGS. 1 and 2 is rectangular or even square. The outer excitation coil 22 encloses the outer periphery of the chamber 12 almost completely. Only in the area of electrical connection means 26, 28 does the geometry of the coil 22 have a kind of slit. To achieve the lowest possible inductance L, however, it is advantageous to provide a coil 22 provided with only one turn. In the present exemplary embodiment, the geometry of the coil 22 and the geometry of the vacuum chamber 12 are adapted to the geometric arrangement of a total of four substrates 16. The outer circumference of the substrate arrangement comprising a total of four substrates 16, 20 on the lower substrate holder 14 shown schematically in FIG. 2 has approximately equidistant distances to the approximately completely rotating exciter coil 22. It is further contemplated that the excitation coil 22 and the gas inlets not shown in the figures for the supply of reaction gases centrally between the substrates 16, 20 is arranged.

This is illustrated by the horizontal axis of symmetry in FIG. A symmetrical arrangement of the coil 22 with respect to the substrates 16, 20 may provide approximately identical conditions for a coating process of oppositely disposed substrates 16, 20.

Although the treatment device 10 is shown lying in FIG. 1, that is to say with horizontally oriented substrates 16, 20, a vertical arrangement of the substrates 16, 20 and of the associated substrate holders 14, 18 turns out to be advantageous. Any gravity-related effects can be compensated or bypassed in this way. Both substrates, which are then spaced apart in the horizontal direction, can thus be treated in an approximately identical manner with the intermediate plasma 80.

FIG. 3 shows an alternative embodiment of a vacuum chamber 30. This has a circular shape with an excitation coil 32 also located outside the chamber 30. Similar to the plan view according to FIG. 2, the lateral wall of the vacuum chamber 30 is not explicitly shown here. It lies in the region of the induction-permeable surface portion 34.

FIG. 4 shows a further embodiment of a vacuum treatment device based on FIG. 1, at least in regions. In contrast to According to FIG. 1, the external excitation coil 40 has two windings 36, 38 which run helically in the vertical direction, ie along the coil axis. In contrast to the configurations according to FIGS. 1 to 4, all configurations of FIGS. 5 to 8 have internal coil arrangements. The excitation coils 50, 56, 62 are in each case within the vacuum chamber 60.

In the embodiment sketched in FIG. 5, the coil 50, which continues to laterally surround the space between the substrates 16, 20, has a single coil winding 52, which is encased by an insulation 54. As a result, a purely inductive coupling between the coil 50 and the plasma 80 is favored.

In contrast to this, the coil 56 according to FIG. 6 is arranged as a spiral-shaped flat coil between the opposing substrates 16, 20 or substrate holders 14, 18. In this case, the coil 56 has individual windings 57, 58 which run concentrically into one another and are connected to one another in an electrically spiral manner. The individual windings 57, 58 or the entire spiral-like flat coil body 56 has an internal electrical conductor 52, which are provided with a surrounding insulation 54.

In this embodiment, excitation coil 56 and the plasma 80 to be generated come to lie almost overlapping each other. Here, too, provision is made for the coil 56 to be arranged as centrally as possible between the two opposing substrates 16, 20.

In contrast to the winding insulation of the coil 56 according to FIG. 6, according to the further embodiment according to FIG. 7 it is provided to arrange a coil body 62, which is not insulated per se, between two insulating layers 66, 68. The insulating layers 66, 68 divide the vacuum chamber 60 into an upper and a lower part. With such a configuration but also independently of the respective coil arrangement, hermetically separated regions can be provided by means of a single coil arrangement. be formed within the chamber 60, for example, to treat the opposite, a respective sub-chamber associated substrates 16, 20 different. In this case, provision may be made in particular to hermetically separate the region formed by the induction-permeable shields 66, 68 from the surrounding vacuum chamber 60. For example, the shields 66, 68 formed of glass or of a ceramic material can be sealingly arranged on the inner wall of the vacuum chamber 60.

It is also conceivable to embed the coil 62 in a specially provided coil housing without connection to the chamber wall. Thus, e.g. in the coil area e.g. be set to a different pressure level than in the surrounding chamber 60, so that in the immediate vicinity of the coil 62 no plasma ignition takes place and the coil 62 are exposed to no or only a negligible plasma treatment.

Finally, the embodiment according to FIG. 8 shows that coils 56 which are spiral-shaped and have just been formed can be arranged not only between the substrates 16, 20 but also outside the substrate gap. In this case, they are arranged outside the substrate interstice facing the respective rear sides of the substrates 16, 20 or the associated substrate holder 14, 18 facing away from the substrate interstice. In this embodiment, it is provided to arrange an upper coil 56 above the upper substrate holder 18, that is to say on a side of the substrate holder 18 facing away from the substrate gap, while the same applies to the lower excitation coil 56 in a corresponding manner. The excitation coils 56 are further arranged inside the vacuum chamber 60. However, they can also be arranged outside the vacuum chamber 60, provided that the chamber walls facing the coils 56 are sufficiently permeable for the coupling of electromagnetic energy into the interior of the vacuum chamber 60. Although all embodiments shown in the figures show a horizontal arrangement of the substrates 16, 20 and coils 22, 32, 40, 50, 56, 62, according to the invention, in particular, the substrates 16, 20 and with them also the To arrange coils 22, 32, 40, 50, 56, 62 vertically.

Furthermore, it is also conceivable in principle to arrange the spiral-type flat coils 56, 62 shown in FIGS. 6 to 8 not only inside but also outside the vacuum chamber 60. In this case, however, the coil 56, 62 facing chamber wall would be made of a permeable for inductive excitation material.

FIG. 9 shows a further conceivable arrangement in which two flat coils 62 oriented in a spiral manner in parallel with one another are arranged between the substrates 16, 20 to be treated. The coils 62 are also hermetically separated from the vacuum chamber 60 enclosing them by means of induction-impermeable shields 66, 68. Thus, on the one hand in the coil region between the shields 66, 68 in comparison to the surrounding plasma chamber different boundary conditions are created, which effectively prevent ignition of the plasma between the coils 62.

Furthermore, by the arrangement of two spiral-like coils, a completely symmetrical coil arrangement with respect to the oppositely arranged substrates 16, 20 can be provided. Any electrical contacting means for the coils 62 running parallel to the surface normal of the substrates 16, 20 may be arranged symmetrically with respect to the plane of symmetry of the vacuum chamber 60 and the substrates 16, 20.

Similarly, with the embodiment of FIG. 10, unlike the embodiment of FIG. 8, the two coils 62 disposed outside the treatment space formed between the substrates 16, 20 do not have their own insulation 54 but each of them by a shield 62, 66 from the substrates 16, 20 are separated. In this respect, FIG. 11 shows a further embodiment in which two substantially planar excitation coils 62 are respectively provided facing a rear side of oppositely arranged substrates 16, 20 or substrate holders 14, 18. The two coils 62 are in this case arranged outside the substrate gap 100, which is delimited in the direction of the surface normal of the substrates 16, 20 by the substrates themselves or by the substrate plane not explicitly shown. Perpendicular thereto, ie, in the direction of the substrate plane, the intermediate space 100 is, on the other hand, limited by the substrate edges, which are identified in FIG. 11 by means of an imaginary edge-side connecting line 102.

In addition to this, a further excitation coil 22 is provided, which is designed comparable to the coil 22 shown in FIG. Relative to the surface normal of the substrates 16, 20, although it is arranged approximately in the middle between the substrates 16, 20, or between the substrate holders 14, 18. In the plane perpendicular thereto, however, it lies with its circumference outside the gap 100 and surrounds it in the circumferential direction. The embodiment according to FIG. 12 shows a further coil arrangement in which two excitation coils 50a, 50b are integrated in the wall of the vacuum chamber 60. The coils 50a, 50b are arranged in the upper and lower transition regions or in corners, thus in the transition between a side wall and a bottom or cover section of the vacuum chamber 60. Similar to the embodiment shown in FIG. 5, the coils 50a, 50b each have a single turn, or an electrical conductor 52 with an insulation 54.

Although the excitation coil 50a, 50b may be associated with the interior of the vacuum chamber 60, they are outside the substrate interstice formed by the substrates 16, 20, both in terms of the areal extent of the substrates 16, 20 and with respect to the surface normal of the substrates 16, 20 100th Instead of integration into the chamber wall are Furthermore, any desired configurations are conceivable in which at least one excitation coil 50a, 50b is arranged in the direction of the surface normal of the substrates 16, 20, as well as perpendicular thereto, ie in the transverse or circumferential direction within and / or outside the vacuum chamber 60.

In a further embodiment according to FIG. 13, a total of three individual excitation coils 22a, 22b, 22c are provided, which in each case can be configured comparable to the coil 22 shown in FIG. The coils 22a, 22b, 22c are aligned substantially parallel to one another and extend in the circumferential direction of the substrates 16, 20, or the substrate carrier, outside of the substrate gap 100. In the direction of the surface normal of the substrates 16, 20 is only the middle coil 22b within the two substrate planes, while the two outer coils 22a, 22c are formed substantially symmetrical to each other and symmetrical to the two substrates 16, 20 are arranged. The two outer excitation coils 22a, 22c are in this case related to the surface normal of the substrates 16, 20 at a level which is assigned to the substrate rear side, consequently to the side of the substrates 16, 20 remote from the substrate interstice. Moreover, in the embodiment according to FIG. 13, almost the entire side wall 24 is designed as a permeable surface section, so that the electromagnetic radiation which can be provided by the coils 22a, 22b, 22c can be coupled into the interior of the vacuum chamber as unhindered as possible. Although the embodiments shown in the figures show substantially horizontally oriented substrates, the invention is preferably to be implemented in a rotated, vertical configuration in which the substrates 16, 20 and the various excitation coils are oriented rotated through approximately 90 °.

Although the same or technically largely identical components are denoted by the same reference numerals in the figures. Thus, the multiply provided excitation coils 56, 62, shown in FIGS. 8 to 13, can 50a, 50b, 22a, 22b, 22c may each be formed substantially identically. However, it is also conceivable that, for example, excitation coils provided with the same reference number, such as the coils 56 shown in FIG. 8, are designed differently.

As a result, e.g. a spatial inhomogeneity of the plasma excitation as well as a fine adjustment of the energy injection into the vacuum chamber are deliberately provided. Finally, with differently dimensioned or differently dimensioned excitation coils 56, 62, 50a, 50b, 22a, 22b, 22c, different treatment results can be generated on the mutually opposite substrates 16, 20.

With the treatment device shown, in particular, flat and flat-shaped wafer-like substrates for forming thin-film photovoltaic modules can be provided with intended coatings.

LIST OF REFERENCE NUMBERS

10 vacuum treatment device

 12 vacuum chamber

 14 substrate holder

 16 substrate

 18 substrate holder

 20 substrate

 22 coil

 24 permeable area section

 26 contact

 28 contact

 30 vacuum chamber

 32 coil

 34 permeable surface section

 36 coil winding

 38 coil winding

 40 coil

 50 coil

 52 electrical conductors

 54 insulation

 56 coil

 57 coil winding

 58 coil winding

 60 vacuum chamber

 62 coil

 66 insulation

 68 insulation

 80 plasma

 100 substrate space

Claims

Patent claims Anspruch [en] A device for plasma-assisted treatment of at least two substrates (16, 20), comprising: a vacuum chamber (12; 30; 60) in which at least two substrates (16, 20) face each other at a predetermined distance and with their surfaces to be treated and having a plasma generating device, which has at least one excitation coil (22; 32; 40; 50; 56; 62) for the inductive excitation of at least one plasma (80) located between the substrates (16, 20). The device of claim 1, wherein the excitation coil (22; 32; 40; 50; 56; 62) extends circumferentially outside a gap (100) formed between the substrates (16,20). An apparatus according to claim 1 or 2, wherein the plasma generating means (22; 32; 40; 50; 56; 62) is configured to inject electromagnetic energy into the plasma (80) to be operable in the H mode. Device according to one of the preceding claims, wherein the at least two substrates (6, 20) can be arranged spaced apart in the direction of their surface normals and the at least one excitation coil (22; 32; 40; 50; 56; 62) interposes with respect to the surface normal the substrates (16, 20) extends. Apparatus according to any one of the preceding claims, wherein said at least one excitation coil (22; 32; 40; 50; 56; 62) is disposed outside or within said substantially overlapping one another Substrate levels extends. 6. Device according to one of the preceding claims, wherein the excitation coil (22; 32; 40) substantially encloses an intermediate space (100) formed between the substrates (16, 20) in the circumferential direction. 7. Device according to one of the preceding claims, wherein the at least one excitation coil (22; 32; 40) outside the vacuum chamber (12; 30) is arranged. The apparatus of claim 7, wherein the vacuum chamber (12; 30) has an induction-pervious surface portion (24; 34) facing the excitation coil (22; 32; 40) which is substantially permeable to the magnetic portion of electromagnetic radiation. 9. Device according to one of the preceding claims 1 to 5, wherein the at least one excitation coil (50; 56; 62) within the vacuum chamber (12; 30; 60) is arranged. A device according to any one of the preceding claims, wherein the excitation coil (56; 62) comprises a plurality of helical turns (57, 58) extending in a plane substantially parallel to the plane of the substrate. An apparatus according to claim 10, wherein the turns (57, 58) of the excitation coils (56, 62) are individually or bundled electrically insulated from the plasma (80) to be generated. 12. Device according to one of the preceding claims, wherein the geometric configuration of the excitation coil (22; 32) of the geometric configuration and / or the geometric arrangement of at least one attachable to a substrate holder (14, 18) substrate (16, 20) speaks. 13. Device according to one of the preceding claims, wherein the at least one excitation coil (22a, 22b, 50a, 50b) with respect to a surface normal of the at least one substrate (16, 20) outside the substrate gap (100) is arranged. 14. Device according to one of the preceding claims, wherein for the holder of the substrates (16, 20) provided substrate holder (14, 18) have no maintenance of the plasma (80) influencing function. 15. Device according to one of the preceding claims, wherein the  Plasma generating means (22; 32; 40; 50; 56; 62) for generating a plasma (80) using the electron cyclotron wave resonance effect (ECWR) is formed. 16. Apparatus according to claim 15, wherein the plasma generating means is adapted to form a further static magnetic field oriented perpendicular to the axis of the excitation coil (22; 32; 40; 50; 56; 62). 17. Device according to one of the preceding claims, wherein the substrates (16, 20) in vertical alignment, are treatable with a substantially horizontally oriented surface normal. 18. Device according to one of the preceding claims, wherein the  Plasma (80) in terms of its spatial extent and / or in terms of its position and orientation substantially symmetrically between the substrates (16, 20) can be generated. 19. Device according to one of the preceding claims, wherein the Plasma chamber (12) in at least two, each a sub-plasma aufwei- and at least one substrate (16, 20) receiving partial chambers can be divided, wherein the at least two partial plasmas by means of a common plasma generating means (22; 32; 40; 50; 56; 62) can be generated. 20. Device according to one of the preceding claims, wherein two mutually parallel, each spirally formed excitation coils (62) in the space between the opposing substrates (16, 20) are arranged. 21. A method for plasma-assisted treatment of at least two substrates (16, 20) with the following steps: Arranging at least two substrates (16, 20) at a predetermined distance from one another in a vacuum chamber (12; 30; 60), wherein the substrates (16, 20) with their surfaces to be treated are arranged facing each other, inductive production of a plasma (80) for the surface treatment of the substrates (16, 20) by means of a plasma generating device having at least one excitation coil (22; 32; 40; 50; 56; 62), wherein the plasma (80) is formed between the at least two substrates (16, 20). 22. The method of claim 21, wherein the at least two substrates are arranged in vertical alignment in the vacuum chamber (12; 30; 60). 23. The method according to any one of the preceding claims 21 or 22, wherein the plasma chamber (12) in at least two, each having a partial plasma and at least one substrate (16, 20) receiving sub-chambers is divided and the at least two partial plasmas by means of a common plasma generating device (22 32, 40, 50, 55, 56, 58; 62, 64) are generated. 24. The method according to any one of the preceding claims 21 to 23, wherein the opposing substrates (16, 20) are treated substantially identically. 25. The method according to any one of the preceding claims 21 to 24, wherein the oppositely disposed substrates (16, 20) are coated with substantially identical plasma deposition rates.