DE102012111636A1 - Device for thermal treatment of substrates in treatment chamber, comprises transport device for transporting substrates, gas conducting device, and radiation device comprising electrode pair comprising anode, cathode and discharge chamber - Google Patents

Abstract

Device for thermal treatment of substrates (2) in a treatment chamber, comprises (a) a transport device in the treatment chamber for transporting the substrates, (b) a gas conducting device (8) for supplying and discharging an inert gas, and (c) a radiation device in the treatment chamber, for irradiating the substrates, which is arranged immediately above the surface of the substrates, and comprises at least one electrode pair (5) comprising an anode (52), a cathode (51) and a discharge chamber, in which a gas discharge with emission of electromagnetic radiation, is generated. Device for thermal treatment of substrates (2) in a treatment chamber, comprises (a) a transport device in the treatment chamber for transporting the substrates, (b) a gas conducting device (8) for supplying and discharging an inert gas, and (c) a radiation device in the treatment chamber, for irradiating the substrates, which is arranged immediately above the surface of the substrates, and comprises at least one electrode pair (5) comprising an anode (52), a cathode (51) and a discharge chamber between the anode and the cathode, in which a gas discharge with emission of electromagnetic radiation, is generated. The anode and the cathode are respectively connected to a voltage supply. Independent claims are also included for: (1) a system for producing and subsequently thermally treating coated substrates, comprising a device for depositing thin functional layers on the substrates at low temperature, and the above device for thermal treatment of substrates; (2) thermally treating the substrates in the treatment chamber, comprising (i) introducing the substrates into the treatment chamber by the transport device, (ii) filling the treatment chamber with an inert gas using the gas conducting device, and (iii) heating the substrates by absorbing the radiation of the radiation device, where upon applying a high voltage between the anode and the cathode, a gas discharge emitting electromagnetic radiation, is generated; and (3) producing and subsequently thermally treating the coated substrates, comprising depositing the thin functional layers on the substrates at low temperature, and the above method.

Description

The invention relates to a device and a method for the thermal treatment of substrates, in particular for the thermal aftertreatment of coated substrates. The invention also relates to a system and method for making and subsequently thermally treating coated substrates.

For the thermal treatment of substrates, a heating device is typically used in a treatment chamber. The substrate is usually completely heated. These processes typically last from a few minutes to hours and are not suitable for temperature-sensitive substrates that change or are even destroyed by temperature stress.

In photovoltaics, functional layers, for example transparent conductive oxides (TCO) or low-E layer systems (layer stacks with low emissivity), are applied to glass substrates or plastic substrates and then tempered in a short time, so that without thermal loading of the substrates achieves the desired properties of the functional layers can be. Flash lamps are typically used to flash-coat coated substrates.

In the DE 10 2006 005 025 A1 describes a process for the thermal aftertreatment of highly conductive, transparent metal oxide layers by means of flash-lamp annealing, in which a liquid composition containing an electrically conductive metal oxide, and a dispersant, is applied in the form of a layer on a substrate. Thereafter, the layered composition is irradiated with a polychromatic radiant flash, wherein a halogen lamp or Xe gas discharge lamp having wavelengths of 180 nm to 2500 nm and a duration of the radiation flash of 0.01 ms to 10000 ms and an effective power density of 0 , 01 kW / cm2 to 200 kW / cm2 is used. Thus, a substrate can be equipped with a transparent, electrically conductive layer without thermal stress.

Currently, conventional flash lamps have a poor light emission in the UV range due to the design. The flashlamp typically consists of a glass tube with two electrodes arranged in the glass tube at the opposite ends of the glass tube. When a voltage is applied between two electrodes, a gas discharge is generated with the emission of electromagnetic radiation. This gas discharge emits visible and invisible (UV, IR) light. The UV light is absorbed almost completely within the glass in a wavelength range between 400nm and 200nm partially and below 200nm and does not leak out. As a result, flash lamps emit mainly visible light.

However, functional layers such as TCO and low-E layer systems absorb only slightly in the range of visible light, so that a large proportion of the light generated by flash lamps can not be used. An increase in the UV light emission of flash lamps and thus an improvement in their efficiency can be achieved by specific glass with improved UV transmission. For example, quartz glass with a high degree of purity can be used as the lamp body, so that the light absorption in the wavelength range between 400 nm and 200 nm is only slight. The high degree of purity is associated with high costs and economically not suitable.

Due to the absorption of light in the UV range, there is damage to the glass, the so-called solarization, which accumulate over the course of the operation and eventually make a change of the glass required.

The DE 100 39 383 A1 discloses a flash lamp which is particularly suitable for applications in the UV range (wavelength <450 nm). In this case, a low-melting glass with good UV transmission is used for the body of the flash lamp in conjunction with a glass solder-based melting technique for the electrodes. Furthermore, the highest possible xenon filling pressure, a comparatively high charging voltage and an ignition electrode are used. The focal length or the distance between the electrodes is between 15 and 25 mm. Thus one arrives at a good UV yield of an economically producible flash lamp.

Flash lamps with a long lamp length require cooling to ensure the life of the lamps. The cooling is typically by a gas, such as nitrogen or air. For flash lamps with a high, time-averaged power alternative water is used. The cooling medium (water or gas) absorbs UV light below a certain wavelength, so that there is a significant loss of efficiency of the lamps in the UV range, even with a high degree of purity of glass.

At very high light intensities, the inner surface of the glass tube is so strongly heated by the plasma that glass evaporates and condenses again on the inner surface after the gas discharge. The condensed material forms a milky colored film on the inner wall of the glass. This absorbs even more light compared to an unused glass. In particular, then increases the Absorption in the visible range, so that it can lead to overheating of the glass and thus to a bursting of the lamp.

Xenon ions in the plasma of the gas discharge impinging on the negatively charged cathode surface cause so-called cathode sputtering, i. a removal of the cathode material, which then accumulates as a brown precipitate on the inner wall of the glass tube in the region of the cathode during the life of a flash lamp. This precipitate increasingly absorbs light, which in turn can lead to overheating of the glass and thus bursting of the lamp.

The invention is therefore based on the object to provide an apparatus and a method for the thermal treatment of substrates, with which the aforementioned disadvantages are avoided and thus an effective thermal treatment of substrates can be achieved.

This object is achieved by a device with the characterizing features of claim 1 and a method having the characterizing features of claim 14. Advantageous embodiments of the invention are specified in the dependent claims.

According to the invention, the thermal treatment of substrates, in particular the thermal treatment of surfaces of the coated substrates, is carried out by pulsed electromagnetic radiation. The substrates are specifically heated by absorbing the radiation with a specific radiation intensity and duration.

• (a) eine Transporteinrichtung in der Behandlungskammer zum Transport der Substrate durch die Behandlungskammer sowie zum Einschleusen und Ausschleusen der Substrate in die bzw. aus der Behandlungskammer,
• (b) eine Gasführungseinrichtung zur Zufuhr und Abfuhr eines Inertgases in die bzw. aus der Behandlungskammer,
• (c) eine Strahlungseinrichtung in der Behandlungskammer zum Bestrahlen der Substrate, wobei die Strahlungseinrichtung unmittelbar über der Oberfläche der Substrate angeordnet ist, wobei die Strahlungseinrichtung ein oder mehrere Elektrodenpaare umfasst, die jeweils aus einer Anode und einer Kathode bestehen und jeweils an eine Spannungsversorgung angeschlossen sind, wobei zwischen der Anode und der Kathode ein Entladungsraum liegt, in dem eine Gasentladung mit Aussendung von elektromagnetischer Strahlung erzeugbar ist.

The device according to the invention for the thermal treatment of substrates in a treatment chamber comprises the following components:

• (a) a transport device in the treatment chamber for transporting the substrates through the treatment chamber and for introducing and discharging the substrates into and out of the treatment chamber,
• (b) a gas guiding means for supplying and discharging an inert gas into and out of the treating chamber,
• (c) a radiation device in the treatment chamber for irradiating the substrates, wherein the radiation device is arranged directly above the surface of the substrates, the radiation device comprising one or more electrode pairs, each consisting of an anode and a cathode and each connected to a power supply , wherein between the anode and the cathode is a discharge space in which a gas discharge with emission of electromagnetic radiation can be generated.

In contrast to conventional devices for the thermal treatment of substrates in which one or more flash lamps are used in a treatment chamber and gas discharges are generated in the flash lamps, the gas discharge according to the invention is generated directly above the surface of the substrates in the treatment chamber, i. H. without lamp body or without glass between gas discharge and substrates. Due to the lack of glass, the total emitted radiation can reach the substrates with the least possible radiation loss. The light emission in the UV range can be fully utilized and thus thin functional layers, for example transparent conductive oxides or low-E layer systems, can be heated efficiently.

With appropriate design, for. B. at a small distance between the electrode axis and substrate, the plasma of the gas discharge itself contribute to the heating of the functional layers, d. H. It is partly the kinetic energy of xenon particles used and not only the emitted UV light.

In one embodiment of the invention, the cathodes and the anodes, consisting of high-temperature-resistant metal with low electron work function, are arranged in each case on the opposite side walls of the treatment chamber in a row. Preferably, the anodes are arranged on the one transverse to the transport direction side wall and the cathodes on the other side wall.

Advantageously, the chamber wall of the treatment chamber consists of radiation-reflecting material. Preferably, the chamber wall made of aluminum, due to the relatively high reflection in the UV range.

Furthermore, the chamber wall is provided on the inside with an electrical insulator. For example, the treatment chamber can be lined on the inner walls with tiles of quartz glass or aluminum oxide. Alternatively, when using alumina for electrical insulation, the treatment chamber may be made of steel due to the lack of transparency of the alumina.

With increasing distance between the cathode and the anode, the ignition of a gas discharge across the electrode pairs is more difficult. This difficulty in ignition can be eliminated by an external ignition by means of an ignition electrode embedded in the insulator.

Preferably, the ignition electrode extends to the entire distance between the cathode and the anode.

With external ignition, a DC voltage is applied to the electrodes of the lamp and an AC voltage to the ignition electrode.

To avoid unwanted discharge in the treatment chamber, the transport device, such as transport rollers, made of electrically insulating material. Preferably, the transport rollers made of quartz glass, which with cords of z. B. silicate fibers or glass fibers are wrapped around to avoid damage to the substrate.

Xenon is preferably used to generate a light radiation. The filling pressure of the xenon is preferably between 50 mbar and 1000 mbar. In order to achieve a high light emission in the UV range, the filling pressure is preferably 60 mbar. At this pressure, convection heat transport is still possible.

Furthermore, the device according to the invention has a closed gas circulation, which runs through the treatment chamber. In this gas cycle is the gas guide device.

The gas guiding device has at least one vacuum pump, gas guide tubes and a heat exchanger in order to achieve an effective gas flow through the treatment chamber. The heat exchanger can cool the inert gas heated by the gas discharge to an optimum temperature and thus enable efficient and stable radiation. Furthermore, the gas guiding device may include a cleaning unit for removing particles or gaseous impurities.

In order not to lose any gas during the feeding and discharging of the substrates, the gas guiding device additionally has a gas storage container.

The device according to the invention for the thermal treatment of substrates can be integrated in a system in which thin functional layers are specifically tempered directly after the deposition at low temperature. The system can be configured in several ways. For example, a so-called in-line system is used which comprises at least one deposition treatment chamber (coating chamber) and one thermal treatment treatment chamber (annealing chamber). The functional layers are first applied to the substrates in the coating chamber and then thermally treated in the annealing chamber. Alternatively, depositions and thermal aftertreatments can be done in a single treatment chamber.

• (a) Einschleusen der Substrate in die Behandlungskammer mittels einer Transporteinrichtung,
• (b) Befüllen der Behandlungskammer mit einem Inertgas mittels einer Gasführungseinrichtung,
• (c) Erwärmen der Substrate durch Absorption der Strahlung einer unmittelbar über der Oberfläche der Substrate angeordneten Strahlungseinrichtung, umfassend ein oder mehrere Elektrodenpaare, die jeweils aus einer Anode und einer Kathode bestehen und jeweils an eine Spannungsversorgung angeschlossen sind, wobei bei Anlegen einer Hochspannung zwischen der Anode und der Kathode eine Gasentladung erzeugt wird, die elektromagnetische Strahlung aussendet.

The method according to the invention for the thermal treatment of substrates in a treatment chamber comprises the following steps:

• (a) introducing the substrates into the treatment chamber by means of a transport device,
• (b) filling the treatment chamber with an inert gas by means of a gas guiding device,
• (c) heating the substrates by absorbing the radiation of a radiation device located immediately above the surface of the substrates, comprising one or more pairs of electrodes, each consisting of an anode and a cathode and each connected to a power supply, wherein when applying a high voltage between the Anode and the cathode generates a gas discharge that emits electromagnetic radiation.

In one embodiment of the invention, an equal current is maintained between all pairs of electrodes and thus generates an equal radiation intensity. Each pair of electrodes must be connected to an independent power supply, for example a capacitor with a specific charging voltage.

In another embodiment of the invention, the ignition of the gas discharge between the cathode and the anode is carried out by means of an ignition electrode. With external ignition, a DC voltage is applied to the electrodes (cathode, anode) and an AC voltage to the ignition electrode.

To generate a gas discharge, the treatment chamber is filled with xenon, wherein the filling pressure between 50 mbar and 1000 mbar, preferably 60 mbar, may be.

Upon application of a pulsed voltage between the cathode and the anode, a pulsed gas discharge is generated. Thus, the substrates can be irradiated in a pulsed manner with electromagnetic radiation emitted by the gas discharge, preferably short-wave electromagnetic radiation.

The substrates are transported into the treatment chamber and then the treatment chamber is filled with the inert gas. The inert gas can during a treatment in a closed gas circulation are transported, wherein the inert gas is guided by the gas guide device into the treatment chamber and cooled. After the treatment, the substrates are discharged from the treatment chamber and the inert gas is conveyed back into the treatment chamber via the gas guiding device.

In order to optimize properties of the functional layers on substrates, the substrates are subsequently thermally treated directly after deposition of the functional layers at low temperature using the method according to the invention.

The invention will be explained in more detail with reference to an embodiment and an accompanying drawing. The accompanying drawing figure shows a schematic representation of a system according to the invention for coating and subsequent thermal treatment of substrates in longitudinal section.

A so-called in-line system 1 for coating and subsequent thermal aftertreatment of substrates 2 is in 1 shown. The substrate 2 is through a lock 31 through ordinary transport wheels 41 in the coating chamber 11 transported and then the coating chamber 11 evacuated. In the coating chamber 11 becomes a functional layer 21 on the substrate 2 applied. Deposition is typically at low temperature, for example a transparent conductive oxide layer by sputtering at a temperature below 180 ° C.

The substrate 2 is then removed from the coating chamber 11 through transport rollers 42 , consisting of quartz glass, in the previously evacuated annealing chamber 12 transported. In the annealing chamber 12 there are electrode pairs 5 , each made up of a cathode 51 and anode 52 exist and each with an independent power supply (not shown) are connected. The cathodes 51 and the anodes 52 are each introduced in a row on opposite sides in the chamber wall. The annealing chamber 12 For example, it can be made of aluminum and with an electrical insulator 6 , For example, tiles made of quartz glass, be lined.

The annealing chamber 12 is filled with xenon with a filling pressure between 50 mbar and 1000 mbar. In order to achieve a high light emission in the UV range, the filling pressure is preferably 60 mbar. When a high voltage is applied between the cathode 51 and the anode 52 a gas discharge is generated which emits light radiation. For example, a capacitor can be used to absorb electrical energy, wherein the capacitor should be potential-free. The energy can be taken, for example, a transformed and rectified AC voltage, the charge of the capacitors can be done by a separate transformer for each electrode pair transformer winding on the secondary side and subsequent rectification.

The ignition of the gas discharge between the cathode 51 and the anode 52 can through one in the insulator 6 embedded ignition electrode 7 that extends to the entire length between the cathode 51 and the anode 52 extends, take place.

After the end of treatment, the substrate becomes 2 in the previously evacuated chamber 13 transported. After closing the lock 33 between annealing chamber 12 and chamber 13 The xenon is powered by a vacuum pump 81 for xenon via a heat exchanger 82 back to the annealing chamber 12 promoted.

The chamber 13 can already act as a heat exchanger at sufficiently high filling pressure, so that the heat exchanger 82 can be omitted.

For discharging the substrate 2 becomes the chamber 13 ventilated. For a further process cycle, the coating chamber 11 again with the help of a vacuum pump 9 be evacuated.

Alternatively, all process steps (deposits, thermal treatments) via the annealing chamber 12 done alone. This is a storage container 83 required for xenon so as not to lose xenon.

LIST OF REFERENCE NUMBERS

1

 system

11

 coating chamber

12

 annealing

13

 chamber

2

 substratum

21

 functional layer

31

 lock

32

 lock

33

 lock

34

 lock

41

 transport wheels

42

 transport wheels

5

 electrode pair

51

 cathode

52

 anode

6

 insulator

7

 ignition electrode

8th

 Gas guide device

81

 vacuum pump

82

 heat exchangers

83

 reservoir

84

 gas lines

9

 vacuum pump

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

• DE 102006005025 A1 [0004]
• DE 10039383 A1 [0008]

Claims (20)

Device for the thermal treatment of substrates ( 2 ) in a treatment chamber ( 12 ), comprising the following components: (a) a transport device ( 42 ) in the treatment chamber ( 12 ) for transporting substrates ( 2 ), (b) a gas guiding device ( 8th for the supply and removal of an inert gas, (c) a radiation device in the treatment chamber for irradiating the substrates ( 2 ), wherein the radiation device immediately above the surface of the substrates ( 2 ), wherein the radiation device has one or more electrode pairs ( 5 ), each consisting of an anode ( 52 ) and a cathode ( 51 ) and each connected to a power supply, wherein between the anode ( 52 ) and the cathode ( 51 ) is a discharge space in which a gas discharge with emission of electromagnetic radiation can be generated. Device according to claim 1, characterized in that the cathodes ( 51 ) and the anodes ( 52 ) on the opposite side walls of the treatment chamber ( 12 ) are each arranged in a row. Device according to claim 1 or 2, characterized in that the chamber wall of the treatment chamber ( 12 ) of radiation-reflecting material, preferably of aluminum. Apparatus according to claim 3, characterized in that the chamber wall on the inside with an electrical insulator ( 6 ), preferably consisting of quartz glass, is provided. Apparatus according to claim 4, characterized in that at least one ignition electrode ( 7 ) in the isolator ( 6 ) is embedded. Device according to one of the preceding claims, characterized in that the ignition electrode ( 7 ) to the total distance between the cathode ( 51 ) and the anode ( 52 ). Apparatus according to claim 1, characterized in that the radiation device ( 8th ) emits electromagnetic radiation impulsively. Apparatus according to claim 1, characterized in that the transport device ( 42 ) made of electrically insulating material, preferably of quartz glass. Apparatus according to claim 1, characterized in that the inert gas is xenon and its filling pressure between 50 mbar and 1000 mbar, preferably 60 mbar, is located. Device according to one of the preceding claims, characterized in that the device comprises a closed gas circulation passing through the treatment chamber ( 12 ), wherein the gas guiding device ( 8th ) forms part of the gas cycle. Apparatus according to claim 1 or 10, characterized in that the gas guiding device ( 8th ) at least one vacuum pump ( 81 ), Gas guide tubes ( 84 ), and a heat exchanger ( 82 ) having. Apparatus according to claim 1 or 10, characterized in that the gas guiding device ( 8th ) a gas storage tank ( 83 ) having. System ( 1 ) for producing and subsequently thermally treating coated substrates ( 2 ), comprising a device for depositing thin functional layers ( 21 ) on substrates ( 2 ) at low temperature and a device for the thermal treatment of substrates ( 2 ) according to one of claims 1 to 12. Process for the thermal treatment of substrates ( 2 ) in a treatment chamber ( 12 ), comprising the following steps: (a) introduction of the substrates ( 2 ) into the treatment chamber ( 12 ) by means of a transport device ( 42 ), (b) filling the treatment chamber ( 12 ) with an inert gas by means of a gas guiding device ( 8th ), (c) heating the substrates ( 2 ) by absorption of radiation just above the surface of the substrates ( 2 ) arranged radiation device, comprising one or more pairs of electrodes ( 5 ), each consisting of an anode ( 52 ) and a cathode ( 51 ) and each connected to a power supply, wherein when a high voltage between the anode ( 52 ) and the cathode ( 51 ) generates a gas discharge that emits electromagnetic radiation. Method according to claim 14, characterized in that between all electrode pairs ( 5 ) is maintained a same current, so that an equal radiation intensity is generated. A method according to claim 14 or 15, characterized in that the ignition of the gas discharge between the cathode ( 51 ) and the anode ( 52 ) by means of an ignition electrode ( 7 ) is performed. A method according to claim 14, characterized in that the treatment chamber ( 12 ) with xenon with a filling pressure between 50 mbar and 1000 mbar, preferably 60 mbar, is filled. Process according to claim 14, characterized in that the substrates ( 2 ) are pulsed with electromagnetic radiation. A method according to claim 14, characterized in that the inert gas is transported in a closed gas cycle, wherein the inert gas by the gas guiding device ( 8th ) into the treatment chamber ( 12 ) is guided and cooled. Process for the preparation and subsequent thermal treatment of coated substrates ( 2 ), comprising a method for depositing thin functional layers ( 21 ) on substrates ( 2 ) at a low temperature and a method for the thermal treatment of substrates ( 2 ) according to one of claims 14 to 19.

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