DE102008024372B4 - Method for transporting substrates in vacuum coating equipment - Google Patents

Abstract

Method for transporting glass substrates (10) in vacuum coating devices, in which glass substrates (10) are moved in a vacuum chamber (1) on a transport device or lying past a treatment device in a transport direction (9), the glass substrate (10) being in the region the treatment device is exposed to temperatures in the range of the softening temperature and above and temperature-related, unfavorable to the quality of the process effects by alternating movement of the glass substrate (10) in the transport direction (9) and opposite to the transport direction (9) can be prevented.

Description

Hereinafter, a method for transporting glass substrates in vacuum coating equipment is proposed.

In EP 1 460 642 A1 For example, methods for overcoating flexible substrates by thermal processes, ie, sputtering with various coating materials, are described. In this case, the coating source is always below the substrate, because the vapor particles rise and then precipitate on the substrate. The heat energy input required for the evaporation is therefore limited to the evaporator crucible; the substrate, however, is directed within the process area via a cooling roller, so that its temperature always remains low.

US 5,340,454 A and DE 195 00 964 A1 describe, however, vacuum coating systems for multiple coating of the same substrate with different coating materials in the same coating chamber. For this purpose, different coating sources are arranged in the coating chamber, and the substrate passes through the coating chamber several times ("multipass mode") in two opposite transport directions. According to the invention, it is proposed to increase the productivity by grouping together several substrates and exposing them together to the coating.

It is known to transport substrates, for example flat substrates such as architectural glass or photovoltaic cells, rod-shaped and tubular substrates such as glass tubes or substrates with complex three-dimensional shape by vacuum coating equipment and thereby a treatment, for example thermal, physical or chemical coating or etching processes, diffusion processes etc. to suspend. In the case of flat or elongated substrates, the transport of the substrates in horizontal (horizontal) or vertical (standing) position can take place.

Some such processes take place at relatively high temperatures, for example 600 ° C and more. This may result in problems that the material of the substrates becomes soft due to the high temperatures and as a result deforms the substrate by its own weight. It is best to prevent this effect in order to ensure the quality of the process.

For transporting the substrates, for example glass plates, through the process zones of a vacuum coating device in which the substrates are treated and the substrates are exposed to high temperatures, it is advantageous for reasons of temperature resistance and corrosive resistance to the process media to use ceramic transport rollers as transport means for receiving the substrates in be provided lying position.

The processing of glass plates at temperatures in the range of the softening temperature and above is always a problem when the glass plate does not undergo permanent mechanical support, such as by placing the glass plate on a temperature-stable surface as the transport described above. The toughness of the glass material and thus the form retention capacity depends strongly on the temperature. However, depending on the temperature, it is sufficient to give the glass plate only temporary mechanical support in order to preclude permanent changes in shape or to reduce such changes in shape to a tolerable level with regard to machinability.

For the glasses commonly used in photovoltaics, for example, with moving glass plates, every location of this glass plate must receive mechanical support at temperatures in the region of 600 ° C. within a few seconds. This results in a given transport speed requirements for the transport roller distance to be realized. In the case of relatively long in the diffusion technology process times, finite machine length and structurally related minimum transport roller distances can not be ensured in known transport devices due to the required slow transport speed that the above-described mechanical support of the substrates is guaranteed at all times.

It is therefore proposed, in the transport of glass substrates in vacuum coating equipment in which glass substrates in a vacuum chamber on a conveyor or lying in a transport direction to a treatment device over are moved, wherein the glass substrate in the region of the treatment device is exposed to temperatures in the range of softening temperature and above , Temperature-related, the quality of the process adversely affecting effects by alternating movement of the glass substrate in the transport direction and opposite to the transport direction to prevent.

In this way, there is a reciprocating movement with resulting forward movement of the glass substrate through the vacuum chamber, when in the component of the forward movement (ie in the transport direction) a greater distance is traveled than in the component of Backward movement (ie opposite to the transport direction). On the other hand, a stationary oscillation of the glass substrate results when the paths traveled in the component of the forward movement (ie in the transport direction) and in the component of the backward movement (ie opposite to the transport direction) are equal. The discs oscillate z. B. in the process area forward and backward with the same amplitude. After completion of the process, the disc is moved out of the process area, z. B. in the next process chamber or it is transported within the process chamber to the disc length to make room for the next disc, which enters the process area. In this way it is achieved that each location of the glass substrate is mechanically supported at a selectable time intervals despite a very low resulting transport speed, so that heat-induced deformations of the substrate are prevented.

In this case, the movement of the glass substrate in a first embodiment of the method can be followed by a resulting path-time function which results from the superposition of a linear path-time function with a periodic path-time function. The periodic path-time function may be a sinusoid, i. H. a sinusoidal function that is formed from the sine or cosine function by scaling amplitude and frequency and phase shifting. Alternatively it can be provided that the periodic path-time function as a triangular function or trapezoidal function can be displayed.

In another embodiment of the method, the movement of the glass substrate follows a resulting path-time function, which results from alternating composition of movement sections acting in the transport direction with movement sections acting in a direction opposite to the transport direction.

Movement sections can be designed such that they can be represented as a sinusoidal path-time function or as a linear path-time function. For example, a movement section in the transport direction as a sinusoidal path-time function and a movement section opposite to the transport direction can be displayed as a linear path-time function, or vice versa.

Furthermore, it can be provided that the transitions of adjoining movement sections are smoothed so that abrupt changes in acceleration are avoided. Since the total distance traveled transport of the glass substrates due to the described superimposed or compound forward and backward movements may amount to many times the length of the machine, it may come to the deviation of the actual transport track of the intended. With respect to the uniform rotation of the transport rollers, whose diameter dimensional accuracy, storage and speed and acceleration control high demands are placed on the transport device.

To carry out the method described, a vacuum coating device for glass substrates is proposed which comprises a vacuum chamber with a treatment device arranged therein, wherein the glass substrates are exposed to temperatures in the range of softening temperature and above, and a device for transporting the glass substrates through the vacuum chamber, which in turn is a means of transport for receiving the glass substrates in a standing or lying position and a drive means for driving the transport means and which is operable so that temperature-related, the quality of the process unfavorable effects are prevented by a movement of the glass substrate alternately in the transport direction and opposite to the transport direction.

This embodiment is the prerequisite for being able to alternately move the glass substrates forward and backward from a first end to an opposite end of the vacuum coating device with respect to the general transport direction.

In order to make the proposed device flexible with respect to the processes to be performed, d. H. the implementation of different processes with different temperatures, resulting transport speeds, etc., can be further provided that the path-time course of the movement is programmable, so that different forms of movement can be realized. In addition, the transport device can be designed so that the path-time course of the movement can be controlled or regulated. For this purpose, a known control or regulating device can be provided.

In one embodiment of the device can for the horizontal transport of the glass substrates, d. H. in a lying position, be provided that a transport means for receiving the glass substrates and provided with the transport means in operative connection drive means are provided, wherein the drive means is adapted to allow movement of the glass substrates both in the transport direction and opposite to the transport direction. Such a means of transport may comprise, for example, in a manner known per se, a plurality of transport rollers arranged one behind the other in a transport plane, of which at least one part is drivable. Furthermore, it can be provided in this embodiment that the drive device comprises a controllable servo motor.

The proposed device will be explained in more detail with reference to an embodiment and associated drawings. Show

1 a longitudinal section through an exemplary vacuum treatment device with a device for transporting the glass substrates,

2 the path-time course of a first movement form according to the proposed method, and

3 the path-time course of a second form of movement according to the proposed method.

In 1 is a vacuum treatment device with a vacuum chamber 1 and one chamber valve each 2 for insertion and removal of the glass substrates 10 shown, wherein the vacuum chamber 1 by means of vacuum pumps 3 is evacuable, and being in the vacuum chamber 1 by gas supply facilities 4 Process gases can be fed. By thermal insulation elements 5 is a process zone formed by a heating device 6 is heated and in the glass substrates 10 be treated by a diffusion process. These are the glass substrates 10 on an arrangement of transport rollers 7 moving through the process zone. The transport rollers 7 are by a drive device 8th drivable, which is designed so that the glass substrates 10 in the transport direction 9 be moved through the process zone, the glass substrate 10 alternately in the transport direction 9 and opposite to the transport direction 9 is moved.

Examples of such forms of movement with the in 1 shown transport device can be realized in 2 and 3 shown as a path-time diagram, wherein on the x-axis of each diagram is shown a time period of 100 s. The y-axes of the diagrams, over which the path of the substrate is recorded, are equally scaled for better comparability of the two forms of motion. The movement form in 2 has arisen by superposition of a linear path-time function with a periodic path-time function, namely a sinusoidal dependence of the path on time. In contrast, the movement form is in 3 by alternating composition of acting in the direction of transport movement sections with opposite acting to the transport direction movement sections emerged. Forward motion components are each 13 seconds long, while reverse motion components are each 9 seconds long. It can be seen that the two types of movement shown differ both with respect to the frequency with which forward and backward movement alternate and with respect to the resulting speed in the transport direction. As a result, the proposed transport device can be used for many different processes and set to their parameters by reprogramming the motion form.

LIST OF REFERENCE NUMBERS

1

vacuum chamber

2

chamber valve

3

vacuum pump

4

Gas supply means

5

thermal insulation panels

6

heater

7

transport rollers

8th

driving means

9

transport direction

10

glass substrate

Claims (8)

Method for transporting glass substrates ( 10 ) in vacuum coating equipment in which glass substrates ( 10 ) in a vacuum chamber ( 1 ) standing on a transport device or lying in a transport direction ( 9 ) are moved past a treatment device, wherein the glass substrate ( 10 ) is exposed in the region of the treatment device temperatures in the range of the softening temperature and above and temperature-related, the quality of the process unfavorable effects by alternating movement of the glass substrate ( 10 ) in the transport direction ( 9 ) and opposite to the transport direction ( 9 ) be prevented. Method according to claim 1, characterized in that the movement of the glass substrate ( 10 ) follows a resulting path-time function that results from superimposing a linear path-time function with a periodic path-time function. A method according to claim 2, characterized in that the periodic path-time function can be represented as a sinusoid. A method according to claim 2, characterized in that the periodic path-time function as a triangular function or trapezoidal function can be displayed. Method according to claim 1, characterized in that the movement of the glass substrate ( 10 ) follows a resulting path-time function, which is characterized by alternating composition of the transport direction ( 9 ) Acting movement sections with opposite to the transport direction ( 9 ) Acting movement sections arises. A method according to claim 5, characterized in that movement sections can be represented as a sinusoidal path-time function. A method according to claim 5 or 6, characterized in that movement sections can be represented as a linear path-time function. Method according to one of claims 5 to 7, characterized in that the transitions of adjoining movement sections are smoothed.

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