DE102011113294A1 - Vacuum coater - Google Patents

Abstract

The invention relates to a vacuum coating device and a method for vacuum coating a substrate, comprising an evacuable coating space (12) in which a substrate carrier (28) for receiving a substrate (30) to be coated is provided, with an electrode (32) above the substrate carrier (12). 28), with a counter electrode (24) and with a gas supply (22) having at least one gas outlet opening (26) for supplying process gases in the direction of the substrate (30). A distance (d) between the substrate carrier (28) and the electrode (24) can be changed. Furthermore, at least one flow-guiding element is provided between the electrode (24) and the substrate carrier (28), which may be formed as a frame which extends from the electrode (24) in the direction of the substrate carrier (28).

Description

The invention relates to a vacuum coating device with an evacuable coating space, in which a substrate carrier is provided for receiving a substrate to be coated, with an electrode above the substrate support, with a counter electrode, and with a gas supply with at least one gas outlet opening for supplying process gases into the coating chamber.

Such vacuum coating devices are known in principle (cf., for example, US Pat. US 6,626,186 B1 ). They are used for numerous coating tasks. It can be, for example, a CVD process (Chemical Vapor Deposition) or a PECVD process (Plasma Enhanced Chemical Vapor Deposition). In the latter, an RF voltage is applied between the electrode and the counter electrode, thereby generating a plasma. Such processes are used, for example, in the production of solar cells, for example, to apply a nitride coating for passivation of the surface of solar cells.

The problem with such processes is a clean process management in order to apply the most uniform coating of constant thickness without impurities on the substrate surface. The coating result is influenced by numerous process parameters, such as gas composition of the reaction gases, temperature of the substrate to be coated, temperature within the coating chamber, distance between electrode and counter electrode, applied voltage or frequency, flow profile of the process gases, and other parameters.

Even if the relevant process parameters can usually be controlled automatically, there are often drifting processes and uneven coatings that can lead to rejects.

From the DE 10 2008 026 000 A1 Although a vacuum coating apparatus is known in which over the entire width of the surface to be coated of a substrate, a first process gas is admitted into the vacuum chamber, in the narrow sides of the substrate, a second process gas is admitted into the vacuum chamber and during the coating process gas from the narrow sides of the Substrate is sucked out.

However, this is only a vacuum-assisted process with different process gases, without the coating process being supported by an electric field between an electrode and a counterelectrode. The vacuum chamber in question is designed for a continuous process using a coating source such as in the form of a linear magnetron sputtering source.

Against this background, the invention has the object to improve a vacuum coating device according to the aforementioned type such that the coating process can be performed as uniformly as possible and with high stability largely free of impurities. Furthermore, an improved vacuum coating method using a voltage between an electrode and a counter electrode under supply of a process gas is to be specified, which allows the most uniform and stable process control.

This object is achieved in a vacuum coating device according to the aforementioned type in that a distance between the substrate carrier and the opposite electrode is variable.

The object of the invention is completely solved in this way.

While in conventional vacuum coating apparatus, the distance between the electrode and the counter electrode is fixed, the distance between the substrate carrier, on which the substrate is accommodated, and the electrode can be changed in the vacuum coating device according to the invention. By changing the distance between substrate carrier or counterelectrode and electrode, the coating process can be considered in the course of numerous coating cycles changed conditions and it can be stabilized over time drifting coating processes by adjusting the distance between the electrode and counter electrode.

The vacuum coating device according to the invention preferably operates in batch mode. It may be a PECVD process or a CVD process, for example.

In a further development of the invention, a lifting device is provided, by means of which the substrate carrier is movable.

Although it would also be possible in principle to make the electrode height-adjustable, an advantageous embodiment is achieved when the substrate carrier is adjusted by means of a lifting device, in particular if the vacuum coating device is designed with two planes arranged one above the other, between which the substrate carriers pass through anyway a Lifting device can be moved so as to achieve better throughput in a batch plant can. Preferably, in this case, the upper level is used for coating, while the lower level serves as a buffer for finished coated substrates and in conjunction with a suitable handling device allows increased throughput.

In an advantageous development of the invention, the distance between electrode and substrate carrier is automatically adjustable, preferably adjustable as a function of at least one coating parameter by means of a controller.

In this way, an improved process control with automatic control of the distance between the counter electrode and the electrode can be achieved.

The object of the invention is further achieved by a method for vacuum coating a substrate under application of a voltage between a substrate opposite the substrate and a counter electrode while supplying a process gas into the coating chamber, in which a distance between the electrode and the counter electrode is adjusted, preferably automatically is controlled in dependence on at least one process parameter.

As already mentioned above, a more uniform process control with particularly high quality is made possible by such a method.

In an advantageous embodiment of this method, in this case the process gas is supplied via a plurality of gas outlet openings at the electrode and directed by at least one flow guide in the direction of the substrate, wherein an extraction preferably takes place in the bottom region of the coating chamber.

This allows a particularly uniform supply of the process gases from above in the direction of the substrate, whereby particularly uniform coating results can be achieved.

According to an alternative embodiment of the invention, the object is achieved in a vacuum coating device according to the aforementioned type in that extends at least one flow guide between the electrode and the substrate support.

In this way, a particularly homogeneous and uniform coating of the substrate is supported. By using the flow guide between the electrode and the substrate carrier, the process gases supplied from above can be directed particularly uniformly in the direction of the substrate. A lateral escape of the process gases before they have swept over the substrate surface is prevented or minimized in this way.

In a preferred embodiment of the invention, the flow guide is formed as a frame which extends from the electrode in the direction of the substrate carrier.

Here, the at least one gas outlet opening is preferably arranged within a space enclosed by the flow guide.

Further preferably, a plurality of gas outlet openings is provided in the electrode.

By this measure, a particularly uniform surface supply of process gases is ensured from above in the direction of the substrate, resulting in a particularly high coating quality.

In a further advantageous embodiment of the invention, the flow guide is arranged and dimensioned such that between the substrate carrier and the flow guide a gap of at most 20 mm, preferably of at most 10 mm, more preferably of at most 6 mm remains.

In a further preferred embodiment of the invention, the flow guide is arranged and dimensioned such that between the substrate carrier and the flow guide a gap of about 2 to 20 mm, preferably from about 2 to 7 mm, more preferably from about 2 to 5 mm remains.

It has been shown that with such a dimensioning of the gap particularly good coating results can be achieved.

In particular, in conjunction with an automatic adjustment of the distance between substrate carrier and electrode, the remaining gap in the specified range between 2 and 20 mm can be adjusted so that an optimized process control can be achieved.

In a further preferred embodiment of the invention, the substrate carrier on a plate, preferably on a graphite plate, added, which is connected as a counter electrode.

In conventional vacuum coating apparatuses, while normally the substrate carrier itself is connected as a counterelectrode, the use of the plate in this way homogenizes the electric field reached between the substrate and the electrode. Not the substrate itself, but the plate, which is preferably designed as a graphite plate, acts as a counter electrode. In this way, the substrate is enclosed in a more homogeneous field between the further downwardly displaced plate and the electrode. Particular advantages arise when the plate is designed as a graphite plate, since graphite is a particularly good conductor of heat, which contributes to a uniform temperature distribution.

In a further preferred embodiment of the invention, the plate or the graphite plate is heated.

This makes it possible to achieve a particularly uniform heating, in particular when the plate is designed as a graphite plate. While the substrate carrier is heated in conventional systems, the plate on which the substrate carrier is received, can be continuously heated. This ensures a much more uniform temperature. Despite the short cycle times for a coating, the continuously heated graphite plate achieves rapid homogenization of the temperature at the substrate.

In this way, a particularly homogeneous and uniform coating is supported.

It is understood that the features of the invention mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the invention.

Further features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the drawings. Show it:

1 a cross section through a vacuum coating device according to the invention in a highly simplified, schematic representation; and

2a) to c) is a schematic representation of a vacuum coating system with three coating cells, a service cell and a load cell, which are arranged pentagonally around a central distribution cell, wherein in a) to c) different types of use are shown.

In 1 is a vacuum coating device according to the invention in total with the numeral 10 designated.

The vacuum coating device 10 has a coating room 12 on top of a floor 16 , Walls 18 and a lid 14 is enclosed airtight. The coating room 12 has an upper level 38 and below that a lower level 40 on. Both in the upper level 38 as well as in the lower level 40 can be a substrate carrier 28 be included. The substrate carrier 28 can have an associated door 48 in the wall 18 by means of a handling device 52 to the upper level 38 be extended or retracted. For inclusion in the upper level here associated roles serve 36 by means of vacuum feedthroughs from outside the coating space 12 are actuated and by axial movement in the wall 18 can be sunk.

Also in the lower level are transport wheels 46 provided for receiving a substrate carrier 28 serve, in turn, with the door open 50 by means of an associated handling device 54 to the lower level 40 of the coating room 12 can be extended or retracted.

One in the coating room 12 located substrate carrier 28 lies in the wall 18 retracted transport rollers 36 on a plate 32 on, which preferably consists of graphite and by means of a lifting device 42 can be moved in the vertical direction. The lifting device 42 includes a lifting drive 64 , Which may be, for example, an electric cylinder, by means of which a piston is moved in the vertical direction controlled.

The graphite plate 32 is heated, including on its underside a plurality of heating elements 34 , z. B. resistance heating elements, are provided, over the entire lower surface of the plate 32 are arranged evenly distributed. According to 1 is on the substrate carrier 28 a flat substrate 30 recorded in the coating apparatus 10 can be coated. The plate 32 is connected as a counter electrode.

Above the substrate 30 is an associated planar electrode 24 at a distance d from the substrate carrier 28 arranged. The electrode 24 is from a variety of gas vents 26 interspersed, which is distributed in a grid over the entire surface of the electrode 24 extend. The gas outlet openings 26 are used to supply process gas for a vacuum coating process, via a connected gas supply 22 from outside the coating chamber 12 can be supplied.

Between the plate 32 and the electrode 24 A voltage is applied (not shown), which may be an RF voltage, when a PECVD process is to be carried out under vacuum in the coating room.

During a coating process, the process gas enters as indicated by the arrows 74 indicated, evenly down towards the substrate 30 out. In order to avoid a lateral escape of the process gas and to ensure a uniform access of the process gas to the substrate surface, is a flow guide 70 intended. It is a circumferentially closed frame, located at the bottom of the electrode 24 is attached and down to just above the substrate support 28 extends.

Between the lower end of the flow guide or frame 70 and the substrate carrier 28 remains a gap s, which is preferably in the range of about 2 to 20 mm, in particular 2 to 5 mm, and preferably by means of the lifting device 42 is variable depending on at least one process parameter. The lifting device 42 This is done via a central control 60 controlled, as via a control line 66 is indicated. Is purely schematic in the coating chamber 12 a sensor 62 represented by a line 68 with the central control 60 is coupled. This may be, for example, a temperature sensor, a pressure sensor, a sensor for detecting a specific gas partial pressure, etc. It is understood that the sensor 28 is merely indicated purely schematically and can be designed as any sensor or that a number of different sensors may be provided with the control 60 keep in touch. Anyway, with the help of the controller 60 the distance d between the substrate carrier 28 and electrode 24 or the gap s between the lower end of the flow guide or frame 70 and the substrate carrier 28 be adjusted depending on one of the process parameters to ensure optimized process control.

The coating chamber 12 can with the help of a vacuum pump 20 be evacuated. The vacuum pump 20 has a plurality of suction openings 21 preferably located in the bottom area of the coating space 12 are arranged evenly distributed.

Through the flow guide or the frame 70 is a very uniform access through the electrode 24 supplied process gases to the surface of the substrate 30 guaranteed.

The graphite plate 32 , which is connected as a counter electrode, serves to homogenize the electric field, since the graphite plate 32 easier to contact than the substrate carrier. In addition, graphite is a very good conductor of heat, which ensures a uniform temperature distribution over the entire surface. This results in a particularly uniform temperature distribution over the entire graphite plate 32 and thus also over the substrate carrier 28 and ultimately the substrate 30 , which leads to a correspondingly homogeneous coating result.

By dividing the coating room 12 in an upper level 38 and a lower level 40 In combination with associated handling devices and associated loading and distribution devices, a particularly fast throughput can be ensured.

If a coating process in the upper range 38 of the coating room 12 is finished, then the substrate carrier 28 with the substrate on top 30 by means of the lifting device 42 to the lower level 40 be moved. It can then open doors 48 respectively. 50 by means of the handling device 52 a new substrate carrier are retracted with a substrate to be coated, as indicated by the arrow 56 is indicated. At the same time, the substrate carrier 28 with the finished coated substrate thereon 30 from the lower level 40 with the door open 50 about the handling device 54 be extended, as indicated by the arrow 58 is indicated.

It is understood that instead of two separate doors 48 . 50 according to 1 Also, a common continuous door or lock can be provided.

The system preferably operates in clocked mode in batch mode.

In 2 is the basic structure of a vacuum coating system shown and total with numeral 80 designated. The vacuum coating system 80 according to 2a) comprises three coating cells P1, P2, P3 and an identically structured service cell M, as well as a load cell 82 , which is outside a distribution cell 84 are arranged around, which has the shape of a regular pentagon. The coating cells P1, P2, P3 and the maintenance cell M are each via an associated lock or door with the distribution cell 84 coupled.

Each coating cell P1, P2, P3 and the maintenance cell M is through a vacuum coating device 10 formed in the manner described above.

In the present case, the same coating process is carried out in all the coating cells P1, P2, P3. The parallel operation of the coating cells P1, P2, P3 ensures an increased throughput. The capacity of the coating cells P1, P2, P3 is now designed so that three coating cells are sufficient to ensure the nominal throughput. The maintenance cell M now has an identical structure as the Coating cells P1, P2, P3 and thus serves as a reserve capacity. This means that the coating process operates at nominal throughput while maintaining in one cell, in the maintenance cell M, maintenance work, e.g. As cleaning work and the like can be performed without the nominal throughput is impaired.

2 B) shows another state of the vacuum coating system 80 ' in which the previously according to 2a) used as a cell in the process cell P3 is now used as a maintenance cell M, and in which the previous maintenance cell M is now operated as a coating cell P3 in the process.

There is thus the same number of coating modules as before available, while at the same time another of the modules is used for maintenance, as indicated at M.

2c) shows another state of the vacuum coating system 80 '' , in which now the previously according to 2 B) cell used as a coating cell P2 is now used as a maintenance cell M, while the previous maintenance cell is used as a coating cell P2.

Thus, it is thus always possible to achieve the nominal throughput of the entire vacuum coating system, while always one of the cells is offline for maintenance purposes. Overall, with such a design, an operational readiness (uptime) of about 97% can be guaranteed.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 6626186 B1 [0002]
• DE 102008026000 A1 [0005]

Claims (13)

Vacuum coating device with an evacuable coating space ( 12 ), in which a substrate carrier ( 28 ) for receiving a substrate to be coated ( 30 ) is provided with an electrode ( 24 ) above the substrate support ( 28 ), with a counterelectrode ( 32 ), and with a gas supply ( 22 ) with at least one gas outlet opening ( 26 ) for supplying process gases into the coating space ( 12 ), characterized in that a distance (d) between the substrate carrier ( 28 ) and the electrode ( 24 ) is changeable. Vacuum coating device according to claim 1, characterized in that a lifting device ( 42 ) is provided, by means of which the substrate carrier ( 28 ) is movable. Vacuum coating device according to claim 1 or 2, characterized in that the distance (d) between electrode ( 24 ) and substrate carrier ( 28 ) is automatically adjustable, preferably as a function of at least one coating parameter by means of a controller ( 60 ) is adjustable. Vacuum coating device with an evacuable coating space ( 12 ), in which a substrate carrier ( 28 ) for receiving a substrate to be coated ( 30 ) is provided with an electrode ( 24 ) above the substrate support ( 28 ), with a counterelectrode ( 32 ), and with a gas supply ( 22 ) with at least one gas outlet opening ( 26 ) for supplying process gases into the coating space ( 12 ), in particular according to one of the preceding claims, characterized in that between the electrode ( 24 ) and the substrate carrier ( 28 ) at least one flow guide ( 70 ). Vacuum coating device according to claim 1, characterized in that the flow guiding element ( 70 ) is formed as a frame extending from the electrode ( 24 ) out in the direction of the substrate carrier ( 28 ). Vacuum coating device according to claim 4 or 5, characterized in that the at least one gas outlet opening ( 26 ) within one of the flow guide ( 70 ) enclosed space ( 72 ) is arranged. Vacuum coating device according to claim 6, characterized in that in the electrode ( 24 ) a plurality of gas outlet openings ( 26 ) is provided. Vacuum coating device according to one of the preceding claims, characterized in that the flow guiding element ( 70 ) is arranged and dimensioned such that between the substrate carrier ( 28 ) and the flow guide ( 70 ) a gap (s) of at most 20 millimeters, preferably of at most 10 millimeters, more preferably of at most 6 millimeters remains. Vacuum coating device according to claim 8, characterized in that the flow guiding element ( 70 ) is arranged and dimensioned such that between the substrate carrier ( 28 ) and the flow guide ( 70 ) a gap (s) of about 2 to 20 millimeters, preferably from about 2 to 7 millimeters, more preferably from about 2 to 5 millimeters remains. Vacuum coating device according to one of the preceding claims, characterized in that the substrate carrier ( 28 ) on a plate ( 32 ), preferably on a graphite plate, which is connected as a counter electrode. Vacuum coating device according to claim 10, characterized in that the plate ( 32 ) is heated. Method for vacuum coating a substrate ( 30 ) under application of a voltage between a substrate ( 30 ) opposite electrode ( 24 ) and a counter electrode ( 32 ) with supply of a process gas from above, in which a distance (d) between the electrode ( 24 ) and the counter electrode ( 32 ) is changed, preferably in dependence on at least one process parameter. Method according to Claim 12, in which the process gas is conveyed via a multiplicity of gas outlets ( 26 ) on the electrode ( 24 ) is supplied and by at least one flow guide ( 70 ) towards the substrate ( 30 ), wherein a suction preferably in the bottom region of the coating chamber ( 12 ) he follows.

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