DE102013106734A1 - Evacuable plant chamber of a continuous substrate treatment plant and method of operation of the plant - Google Patents

Abstract

The invention relates to a system chamber of a continuous substrate treatment system with a vacuum access for direct or indirect evacuation of the system chamber and with a transport device for transporting a substrate 6 in a substrate transport plane 5 through the system chamber. In order to improve the evacuation in a system chamber on both sides of the substrate transport level 5 of such a system, a cryopump with at least one cold surface 19 for binding gases present within the system chamber is arranged in the system chamber below and / or above the substrate transport level 5.

Description

The invention relates to improvements in a continuous substrate treatment apparatus for the treatment, for example coating, of plate-shaped substrates, for example glass plates, the substrates, with or without a substrate holder lying on a transport device, i. in a horizontal orientation, or in a vertical or inclined position through a chamber chamber limited by chamber walls or an array of successively arranged plant chambers of a substrate treatment plant, the substrates are subjected to the action of at least one substrate treatment device, such as coating devices, etching devices, etc. On the one hand, the substrate treatment often takes place at a lower pressure (process vacuum) than at atmospheric pressure and, on the other hand, often occurs in a selected, often controlled gas or gas mixture (process atmosphere).

In continuous substrate treatment plants, in contrast to so-called batch substrate treatment plants of the plant chamber or an arrangement of several successively arranged plant chambers, which may be formed, for example, as process chambers, pumping chambers, transfer chambers, etc. In general, at least one each designed as a lock chamber plant chamber upstream and downstream, which can sometimes be supplemented by a respective buffer chambers for coupling to the process environment. In addition, a transport device is arranged in the interior of the substrate treatment plant so that it extends through the two lock chambers and all other system chambers arranged therebetween.

As a result, substrates can be moved in a transport direction through the substrate treatment plant by being introduced into the substrate treatment plant by means of a first lock chamber, transported through the entire arrangement of successively arranged plant chambers by means of the transport device and discharged from the substrate treatment plant by means of a second lock chamber. In this case, the substrates in at least one process chamber are also moved past a substrate treatment device arranged therein and are exposed to the desired substrate treatment. The plane in which the substrates and the transport device are in contact is often referred to as the substrate transport plane.

A process chamber of a continuous substrate treatment plant is regularly subdivided into several compartments, also referred to as sections or sections. As a compartment of a treatment plant is generally understood one of the possible functional units, which are connected to each other in a continuous flow in the transport direction with each other. By means of such functional units, for example, various substrate treatments, evacuation or gas separation are realized. They are separated by partitions,

which have slots in the region of the substrate transport plane through which the substrates are transported.

For the treatment of plate-shaped substrates, transport devices have proven useful which comprise a plurality of transversely mounted to the transport direction of the substrates, rotatably mounted, cylindrical or otherwise shaped transport rollers whose uppermost generatrices define a horizontal transport plane for the substrates and of which at least a portion is driven. If the desired substrate treatment takes place at elevated process temperatures, for example 400, 600 or 800 ° C., it is necessary to produce the transport rollers made of heat-resistant materials, for example ceramics, or to coat them with a heat-resistant material.

When treating the substrates, for example when coating flat glass panes in coating systems, preferably in magnetron sputtering systems operating under high vacuum, environmental conditions deviating from the ambient air must be provided, for example an inert gas atmosphere or a vacuum. The evacuation and ventilation of the various chambers of such a treatment plant should be as fast as possible and a predetermined Mindestevakuierungsgrad should be achieved. For evacuation vacuum connections are arranged in the various chambers of the treatment plant, which are distributed in the process chamber to individual compartments, so that a compartment can be evacuated directly or indirectly via an adjacent compartment. The partitions between the compartments have, often closable, suction openings, through which an evacuation of an adjacent compartment is possible.

The substrate transport plane in which the substrates are transported through the treatment plant, often represents a resistance in the evacuation, when the pressure conditions in the chamber or in the compartment are such that a gas exchange laterally of the substrates or between them due to the not required degree can be done. This is particularly reinforced when the transport plane is almost closed by screens or fenders, for example, to protect the transport system. To this The space to be evacuated is subdivided into subspaces above and below the substrate transport plane, which would only require compensation processes that are difficult to implement in an efficient treatment process or their own vacuum connections. This would significantly increase the technical and energy costs. Often, the plant design also provides only vacuum connections above the substrate transport plane.

There is a need for an improvement in the evacuation in a plant chamber or, when divided into compartments, in a compartment on both sides of the substrate transport level of a continuous substrate treatment plant, which can be realized inexpensively and with little space and can be retrofitted in existing plant chambers.

This object is achieved by a plant chamber having the features of claim 1 and a method for operating a continuous substrate treatment plant according to claim 4. Embodiments and further developments are the subject of the respective dependent claims.

It is proposed to arrange in a plant chamber below and / or above the substrate transport plane a cryopump having at least one heat sink, which has a cold surface for binding gases. If a heat sink is mentioned below, this should also include a plurality, unless otherwise expressly described.

The terms "above" and "below" are referred to the substrate transport plane and the transport device, so that the substrate is above this plane and the transport device, in particular their components driving the substrate below. The use of "upper" and "lower" chamber sections is also linked to this consideration. In this sense, the terms are used independently of a horizontal orientation of the substrate and are analogously applicable to vertical or inclined substrates.

As a plant chamber in the context of this application, those chambers of a continuous substrate treatment system are to be understood, which are evacuated to generate a vacuum or deviating from the plant environment process environment. It is irrelevant whether the plant chamber or the compartment is evacuated directly via a vacuum pump connection to the chamber or the compartment or indirectly via a vacuum pump connection in an adjacent or more distant chamber or compartment. Accordingly, a vacuum access may be a vacuum pump port or an even closable port to an adjacent compartment or compartment, which itself may in turn be directly or indirectly evacuated.

In the following, when speaking of a plant chamber, the respective statement according to the above-described relationship between the plant chamber and the compartment is also always related to a compartment as a finite section of a chamber, unless expressly excluded.

By using a cryopump as a special type of gas-binding vacuum pumps, on the one hand the evacuation process in the plant chamber can be promoted and accelerated, and on the other hand, gas separation can be realized in the substrate transport plane, where the plant chamber is separated by a dense sequence of substrates or substrate carriers or by endless substrates Areas is divided. Evacuation and gas separation can be achieved by means of cryopumps with low plant outlay and space, so that cryopumps on one or both sides of the substrate transport plane are advantageous where there is too little space for the usual vacuum pump connection and the accessibility or the evacuability by shields, e.g. Radiation shields, diaphragms or special transport mechanisms for the substrate or other installations for areas in the plant chamber is reduced.

The evacuation process is assisted by the binding of gases to one or more cold surfaces of the cryopump, i. H. their removal from the chamber volume. It goes without saying that the cold surface is cooled to a temperature such that expected gas can be bound in the plant chamber for the respective process. For many processes this is especially water vapor, so that the cold surface is preferably brought to a temperature below -120 ° C (T ≈ 153 K). Even temperatures much lower may be required. Thus, at the boiling point of liquid nitrogen (T ≈ 77 K), besides steam, carbon dioxide is also pumpable and at temperatures of about 10 K numerous gases can be pumped except hydrogen, helium and neon.

Also, for the gas separation in the substrate transport plane, the temperature of the cold surface is tuned to the binding ability of the gas or gases to be extracted. This can be advantageous, in particular, for a treatment compartment of a process chamber, where the contamination of a process area with gases from another process area must be regularly prevented or at least minimized, and where often the pressure conditions already permit a gas exchange between the two sides of the substrate transport plane prevent adjacent chamber areas. Such a passive gas separation is supported by means of at least one cryopump according to the invention.

Due to the evacuability of chamber areas by means of a cryopump, a gas separation can be deliberately inserted in accordance with an embodiment of the installation chamber. For this purpose, a gas separation wall is arranged, which lies below the substrate transport plane and thereby divides the plant chamber into at least two chamber sections. The arrangement of the gas separation wall below the substrate transport plane always assigns the substrate to the upper chamber section.

Such a chamber division makes it possible to specifically influence the treatment of the substrate and to reduce the effect on or through spatially spaced installations in the installation chamber. According to alternative variants, in particular the transport device can lie in the same chamber section as the substrate or in the other chamber section. If it is in the other chamber section, it should be subject to a different action, for example by temperature, gas or radiation, than the substrate. For example, it can be protected against unwanted coating or damage from the substrate treatment. On the other hand, if it is in the same chamber section, it can be exposed to the substrate together as a unit of a given action, for example a uniform temperature. The other underlying components, however, are protected from this action, in the above example, a heater arranged in the lower chamber section.

A gas separating wall can also be used as a heat exchanger, in the first of the above-mentioned subdivision variants of the system chamber for heat transfer to the substrate in the second substrate and transport rollers.

In order to selectively expose or withdraw individual components in the installation chamber from an action in one of the chamber sections, the gas separation wall can be guided around the relevant components and can have projections and recesses or can extend like a maander through the installation chamber. Alternatively, it may also have individual passages which approach the projecting elements in such a way that the gas separation remains ensured.

Various types of cryopumps are known, which differ in the type of temperature setting of the cold surface. For example, in the bath cryopump, the cold surface is brought into contact with a cooling fluid. Also, evaporator cryopumps in which the cold surface is cooled by evaporation of a liquid refrigerant, or refrigerator cryopumps that cool by means of compressors are known. Which of the cryopumps are usable depends on the vacuum area to be evacuated or the gas to be bound or the treatment plant concerned.

In the simplest case, a heat sink, which can be adapted in size and shape to the available space, inserted into the plant chamber and optionally flowed through by a liquid or gaseous cooling fluid or designed so that it also to reduce the evacuated Volume is usable. The latter requires the vacuum stability and gas tightness of the heat sink. The variability of the cryopump and the comparatively possible low technical outlay makes it possible, in particular, to retrofit existing pass-through substrate treatment equipment and to adapt it to the respective process requirements.

Process, gas and equipment also influence the choice of bonding mechanism, which in turn depends on the surface material of the cold surface in relation to the gas to be bound. Thus, either a gas binding by cryocondensation or alternatively by cryosorption is possible. Both are physically reversible, with a cryosorption after covering the cold surface with a first layer of adsorbed gas molecules merges into the cryocondensation. The effect of the cryopump is limited by the bondability of the cold surface to the particular cryocondensate.

The described pumping action of the cryopump, in conjunction with the adaptive design of the cryopump, causes, in accordance with one embodiment of the invention, the cryopump to be disposed in the areas of a plant chamber in which there is no vacuum access.

The invention will be explained in more detail with reference to an embodiment. The accompanying figure shows a coating compartment in a process chamber with a cryopump according to the invention.

In Fig. Is shown schematically and without claim to representation of all components, a coating compartment of a continuous sputter coating plant with a double magnetron, each of the two tubular magnetrons comprises a magnetron cathode with a target material and a magnet assembly.

The coating compartment 1 according to the Fig. Is through the outer walls 2 a process chamber of a vacuum treatment plant, of which only the upper and lower are shown due to the sectional view, as well as through the process chamber in successive Kompartments 3 dividing partitions 4 educated. The partitions 4 in the substrate transport plane 5 in which substrates 6 through the coating compartment 1 and every other compartment 3 pass-through sputter coating equipment, substrate passages 7 on. In the illustrated embodiment, successive substrates 6 continuously transported through the plant. The transport takes place by means of a suitable transport system, in this case a series of transport rollers 8th , in transport direction 9 ,

The illustrated coating compartment 1 points in the two partitions 4 above the substrate passages 7 as vacuum access suction openings 17 through which the coating compartment 1 by means of vacuum pumps (not shown) in the upper outer wall 2 the chamber at each of the two adjacent compartments 3 are connected, is evacuated.

Below the substrate transport plane 5 and above the transport rollers 8th is a gas separation wall 20 arranged so that the coating compartment 1 in an upper chamber section 21 and a lower chamber portion 22 is divided. Through the gas separation wall 20 grab the transport wheels 8th only so far through that an unimpeded substrate transport is just possible and otherwise the gaps between the rollers and the chamber wall are almost closed. The gas separation wall 20 reaches as far as the transport rollers 8th and on the outside walls 2 the process chamber and the partitions 4 of the coating department 1 approach that at the prevailing pressure conditions, a gas exchange between the upper chamber section and the lower chamber section is practically vrehindert. The gas separation wall 20 has only a small distance to the substrate 6 on. In the exemplary embodiment, the distance is about 5 cm.

In the lower chamber section 22 below the transport rollers 8th is in the coating compartment 1 and also in the two adjacent compartments 3 almost over the entire length of a heat sink 18 arranged. The heat sink 18 is formed in the embodiment as a meandering arranged cooling coil and traversed by a liquid coolant, which is a temperature at the cold surface 19 forming outer surface of the heat sink 18 from -120 ° C.

LIST OF REFERENCE NUMBERS

1

coating compartment

2

exterior walls

3

compartment

4

partitions

5

Substrate transport plane

6

substratum

7

substrate passage

8th

transport wheels

9

transport direction

10

double magnetron

11

magnetron

12

target material

13

magnet assembly

17

suction opening

18

heatsink

19

cold surface

20

Gas separation wall

21

upper chamber section

22

lower chamber section

Claims (9)

Plant chamber of a continuous substrate treatment plant with a vacuum access for direct or indirect evacuation of the plant chamber and with a transport device for transporting a substrate ( 6 ) in a substrate transport plane ( 5 ) through the plant chamber, characterized in that the plant chamber below and / or above the substrate transport plane ( 5 ) a cryopump having at least one cold surface ( 19 ) for binding gases present within the plant chamber. Plant chamber according to claim 1, characterized in that the cold surface ( 19 ) is cooled to a temperature below -120 ° C. Plant chamber according to one of the preceding claims, characterized in that the cold surface ( 19 ) consists of such a material, that a gas expected in the plant chamber can be bound by cryocondensation or by cryosorption. Plant chamber according to one of the preceding claims, characterized in that in the plant chamber, a gas separation wall ( 20 ), which below the substrate transport plane ( 5 ) and the plant chamber into at least two chamber sections ( 21 . 22 ). Plant chamber according to claim 4, characterized in that the gas separation wall ( 20 ) is designed such that the transport device either in the upper chamber section ( 21 ) above or in the lower chamber section ( 22 ) below the gas separation wall ( 20 ) lies. Plant chamber according to one of the preceding claims, characterized in that a cryopump in a chamber section ( 21 . 22 ) above or below the substrate transport plane ( 5 ), in which there is no vacuum access. Plant chamber according to one of the preceding claims, characterized in that the cryopump by a heat sink ( 18 ) is formed, which is designed to reduce the volume of the system chamber to be evacuated. Plant chamber according to one of the preceding claims, characterized in that the cryopump in a treatment compartment ( 1 ) is arranged a process chamber. A method of operating a continuous substrate processor by exposing a substrate ( 5 ) is introduced into a first vacuum chamber of a treatment plant, transported by a transport device through the vacuum chambers of the treatment plant and thereby treated and then executed from the last vacuum chamber of the treatment plant, characterized in that in at least one plant chamber below and / or above the substrate transport plane ( 5 ) a cryopump is arranged according to one of the preceding claims.

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