EP2744763A1

EP2744763A1 - Method and device for producing a low-emitting layer system

Info

Publication number: EP2744763A1
Application number: EP12756404.5A
Authority: EP
Inventors: Harald Gross; Udo Willkommen
Original assignee: Von Ardenne GmbH
Current assignee: Von Ardenne GmbH
Priority date: 2011-08-19
Filing date: 2012-08-20
Publication date: 2014-06-25
Also published as: US20140199496A1; RU2014110367A; EA201400222A1; WO2013026817A1; EP2744764A1; DE102012200665A1; DE102011089884B4; RU2577562C2; CN103987674A; US20140197350A1; DE102012200665B4; US9453334B2; DE102011089884A1; CN103889915A; WO2013026819A1

Abstract

The invention, which relates to a method for producing a low-emitting layer system, comprising the steps of forming at least one low-emitting layer on at least one side of the substrate by means of deposition and subsequent brief tempering of a deposited low-emitting layer by means of electromagnetic radiation, avoiding an immediate heating up of the substrate, and to a device for performing the method, addresses the problem of improving the optical and thermal properties of a low-emitting layer system without cost-intensive tempering of the entire substrate while maintaining the processability of the low-e coated substrate.

Description

Method and device for producing a

low-emitting layer system

The invention relates to a process for the preparation, in particular tempering of a low-emitting layer system according to the preamble of claim 1 and a

Apparatus for carrying out the method according to the preamble of claim 11.

The invention relates to the preparation, in particular the method of tempering, low-emitting, thin layers, e.g. Silver coatings, which find application in the field of thermal insulation of window and facade glass. The special low-emissivity coatings, also known as low emissivity or short low-e coatings, are used to reduce heat transfer. The low-e coating is characterized by the fact that it has a low thermal emissivity and the

Coating in the visual spectral range is also largely transparent. The aim of the heat-insulating coatings is that the solar radiation can pass through the pane and heat the building, while only a small amount of heat at room temperature is emitted from the building to the surroundings. In another application, the low-e coating is intended to reduce an energy input from outside to inside.

The coatings used for this purpose include, for example, transparent, metallic layers, in particular

Silver-based multi-layer systems, which have a low emissivity and thus a high reflection in the infrared range of the light, with a high transmittance of the entire layer system in the visible spectral range. The commonly used metallic layers are used with a thickness with which they still have the required transparency. For example, silver is still transparent up to a thickness of 20 nm considered. The transparent metallic layers with high reflection in the IR range are generally referred to as IR reflective layers for distinction.

Glass and other non-metallic substrate materials

On the other hand, they usually have a high emissivity in the infrared spectral range. This means that they absorb a high proportion of the heat radiation from the environment and at the same time radiate a large amount of heat to the environment according to their temperature. As a manufacturing method for a low-e coating of

Substrate is usually a vacuum method used, such as evaporation or sputtering technology. However, these thin layers can not be the most ideal compliant deposit and tend to de-wetting, resulting in a corrugated, that is not uniform, layer thicknesses ^¬ distribution result has. However, this energetic limitation of the growth can be partially compensated by the cover layers so that diffusion processes and the leveling of the silver layers occur during a subsequent temperature increase. This results from the shift of the surface energy balance in favor of a wetted configuration. These layers with a homogeneous thickness are characterized by a corresponding decrease in surface resistance and offer the advantage of increased reflection in the infrared region of the light and thus a reduced emissivity.

This effect is known from the production of safety glass. Usually, the already coated glasses are strongly heated in a so-called annealing process above their softening point, typically up to 680-720 ° C., and then cooled rapidly and thus thermally

biased. However, since this means additional costs, only the panes are usually processed into safety glass, the use of which is prescribed. One Most of the discs remain untreated in this respect. In this heat treatment process change due to temperature-induced diffusion processes and chemical

But also the optical properties of the multilayer system, e.g. the reflection color or the transmission, in particular in the visible region of the electromagnetic spectrum. However, these changes are disadvantageous because untreated and treated discs are installed side by side for cost reasons, with optical differences are extremely disturbing. In the prior art, therefore, attempts are made to make the low-e layer systems such that the changes in the optical and thermal layer properties due to the heat treatment of the

coated substrate remain minimal, at least in such a range that visually no difference can be detected.

In addition, these thermally toughened substrates are no longer be assembled. This means that they are no longer shaped, as is usual for glass, by scratching and breaking or otherwise mechanical

can be edited. Furthermore, microscopic

Defects such as micro-cracks in such treated discs lead to spontaneous shattering. To avoid this danger, they must undergo a heat-soak test, i. a hot storage test for toughened safety glass.

In order to assure the manufacturability of the glass, there are efforts in an RTP only the functional layer, i. the low-e layer to heat alone, without that

Substrate to change. By the term "RTP" ("rapid thermal processing") is a fast thermal treatment

meant. So far, experiments with laser are known for this purpose, for example from the document WO 2010/142926 AI, which in the near infrared range, hereinafter referred to as IR range, work. Absorb except in the far IR range the low-e layers are also good enough in the UV range. For both absorption ranges of the low-e layer system, however, the use of line lasers from semiconductor diodes for short-time tempering is very cost-intensive, which is disadvantageous.

The invention is therefore the object of a

to provide an efficient method for producing, in particular for tempering, a low-emitting layer system on at least one side of the substrate, with which the optical and thermal properties of the low-emitting layer system without costly

Heat treatment of the entire substrate and under

Maintaining its assemblability can be improved. The process should be inexpensive and the

Throughput can be increased. Furthermore, one for the

Implementation of the method according to the invention suitable device can be created.

This object is achieved by a method having the features of claim 1. Further embodiments of the invention will become apparent from the accompanying dependent claims.

According to the invention, after the deposition of at least one low-emitting layer system on at least one side of the substrate, at least one

transparent metallic IR reflection layer of a

low-leveling layer system, here as

low-emissive layer, while avoiding immediate heating of the substrate in one

Kurzzeittemperschritt briefly heated by electromagnetic radiation. In this case, the electromagnetic takes place

Radiation at an emission wavelength at which it is at least partially absorbed by the deposited low-emissivity layer and converted to heat. The emission wavelength of the electromagnetic Radiation in the short-time annealing step preferably adjusted or adapted to the material of the low-emitting layer such that the emission wavelength of the

electromagnetic radiation is realized in their absorption range.

As a result of the absorption of the electromagnetic radiation, the low-emittance coating is tempered to a specific temperature and thus restructured in such a way that its properties, in particular the thermal, electrical or optical properties, change, for example compared to the low-emittance layer before the brief annealing Reduced surface resistance and possibly also increases their transmission in the visible and the reflection in the infrared. The electromagnetic radiation for short ^¬ zeittempern set such that the tempered by electrostatic ^¬ magnetic radiation, low-emissivity is preferred

Layer comparable or identical layer properties, in particular optical and / or thermal Schichteigen- create, as the low-emitting conventionally tempered layer of a safety glass. With the

Formulation "the low-emitting, conventional

tempered layer of a safety glass "is a

Annealing meant in the processing of a glass to the safety glass. It has been shown that, in the case of a thermal treatment of the low-e layer deposited on the substrate after deposition, by means of the electromagnetic radiation adapted to the material properties of the low-e layer, the surface resistance of the coating is significantly reduced correlative decrease in emissivity, ie of the

Heat radiation up to 30% comes. Also the optical

Properties, such as reflection colors and transmission, change in style, as is the case with a conventional one

Temperature treatment would be the case. the big advantage It also consists in that due to the low heat ^¬ capacity of the low-emitting coating no extra cooling of the coated substrate is necessary and the substrate is not processed in the annealing step to safety glass. This can be dispensed not only on an energy ^¬ intense heating of the substrate in an oven or on a controlled cooling by means of a subsequent cooling section, but the substrate remains during the RTP to room temperature and can be further processed immediately. Overall, the RTP allows much higher throughput, as the process lasts for much less than a second. In addition, high-priced plant components, such as ceramic rolls for transporting hot glass panes in an oven, can be dispensed with.

According to the invention, the electromagnetic radiation of the low-e layer will now be made by a flash lamp assembly, preferably at least a plurality of flash lamps ^¬, by at least one flash pulse.

Advantageously, a xenon flash lamp is used as the flash lamp. Xenon flash lamps provide a versatile wide-band spectrum from ^¬ with technically usable wavelength of typically 160 nm - 1000 nm, the noble gas xenon.

produces the desired spectrum without harmful additives such as mercury, which also makes the process an environmentally friendly solution. The lower limit of the light emission of 160nm ^¬ is limited by the used quartz glass of the flash lamps. Other types of glass, such as lithium fluoride, also allow emission wavelengths below 160nm, with no use of this material for cost reasons. Above 10000 nm, the intensity of the emitted light is negligible in terms of technical use.

The advantage of using a flash lamp is the relatively low cost and the possibility of customization the operation by adjusting the current density of layer ^¬ system. By operating the flash lamps with high current densities and a considerable amount of UV is generated.

Preferably, the irradiation of the coated layer takes place from the side of the layer system in order to prevent absorption of the electromagnetic radiation for short-term tempering,

especially in the UV range, to avoid through the substrate and thus heating of the substrate. This results in a substrate which can be processed and conventionally finished.

In an advantageous embodiment of the invention, the low-emitting layer in the annealing step in a

Emission wavelength of the electromagnetic radiation in the range of 160 nm to 1000 nm, preferably in a

Emission wavelength of the electromagnetic radiation in

Range of 200 nm to 500 nm and / or in the range of 500 nm to 950 nm, thermally treated. The annealing of the low-emitting layer preferably takes place in the range of the emission wavelength of the electromagnetic radiation of 200 nm to 400 nm and / or 650 nm to 850 nm and / or 160 nm to 200 nm. The radiation of flash lamps also includes

Emission wavelengths down to 160 nm.

These emission wavelength ranges of the electromagnetic radiation include the regions of absorption maxima of the low-emittance layer which are in the range of about 200 nm to 400 nm and 650 to 850 nm. The thermal treatment of the coated, low-emitting layer by irradiation with light in these wavelength ranges enables a reduction in the emissivity or the

Sheet resistance compared to the low-emitting layer before the Kurzzeittemperschritt. In this case, the range of 200 nm to less than 400 nm is advantageous, because in this area the low-e layer by up to a factor of two

absorbed much more radiation than in the range of 650 nm to 850 nm. This allows activation with

lower power densities are achieved. Also, the range of 200 nm to less than 400 nm is technologically better feasible. Preferably, the electromagnetic radiation to the

Tempering step adjusted such that the deposited layer will receive or absorb a predetermined energy input in the irradiation area. By the specifiable energy input is a predetermined final temperature of the low-emitting layer in the irradiation area

reached. In this case, the final temperature corresponds to the temperature of the deposited layer, which is used to heal the structural defects due either to fluctuations in the

Coating conditions and / or in the inadequate for the production of stable layers temperature results, and no damage to the deposited

Layer caused. The adjustment of the energy input therefore takes place taking into account the highest possible layer temperature, i. Maximum temperature of the deposited layers, as well as depending on the

Thickness of the layers to be thermally treated. As a result, a given crystal structure and morphology of the deposited low-e layer is possible.

The adjustment of the energy input of the irradiation is preferably carried out both taking into account the parameters of the electromagnetic radiation, and the temperature of the deposited layer or. from the temperature of

deposited layer resp. the deposited layer system and the substrate. For this purpose, it is provided in a preferred embodiment of the method that a temperature measurement of the low-e layer or the low-e layer and the substrate takes place immediately before the short-term heat treatment step. Based on the measured temperature, the value of the energy input for the thermal aftertreatment is determined and adjusted so that a predefinable End temperature for the Kurzzeittemperschritt is obtained. The energy input is chosen and matched with the highest possible layer temperature, ie maximum temperature of the layers, that the Kurzzeittemperschritt causes no damage to the deposited layer, but achieves predetermined or optimum layer properties. That is, the energy input is adjusted so that it does not exceed the highest possible layer temperature of the abgeschie ^¬ that layer. This is particularly important when irradiating an emission wavelength of the radiation in or near the UV region. In this wavelength range, the radiation is also well absorbed by the substrate, for example of glass, which can result in heating of the substrate. By taking into account the temperature of the substrate and the wavelength of the radiation in the adjustment of the energy input of the radiation, the heating of the substrate can be minimized when adjusting the layer properties of the deposited layer. The low-e layers thus treated in the short-time annealing step offer the advantage of increased reflection in the infrared region of the light and thus reduced emissivity.

In an advantageous embodiment of the invention, the determined energy input becomes a process parameter, such as the energy density, i. Power, exposure surface and duration of the electromagnetic radiation, intended for controlling the Kurzzeitittemperschritts. This means that by adapting the electromagnetic radiation in the short-time annealing step, in particular by adapting the lightning impulses with respect to their pulse shape, duration,

Number, wavelength or current density, the energy density, and thus the optimal layer optimization of low-e layer ^¬ systems, can be made. Advantageously, the flash pulses have a duration of 0.05 ms to 20 ms and a

Pulse energy density in the range of 1 J / cm ² to 10 J / cm ² . It it is advantageous that the pulse intensity, the pulse repetition ^¬ holfrequenz, the pulse shape and the pulse duration of successive flash pulses in dependence on the thickness of the thermally treated layers and taking into account the heat conduction of the substrate can be varied.

In a preferred embodiment of the invention, the flash lamp is operated at a current density greater than 4000A / cm ² without the energy densities described

To change light emission compared to lower current densities. This can be done either by smaller lamp diameters or by shorter flash times. At current densities of more than 4000 A / cm ² , a pronounced UV component can be generated, since the maximum of the

Emission spectrum of the flash lamp with increasing current density shifts to shorter wavelengths. Since the life-expectancy of flash lamps is approximately 10 ⁶ -10 flashes in the order of magnitude of the current density, a large number of substrates can be tempered until a lamp replacement.

High-power flash lamps, for example, are operated at 500 Hz, so that the throughput in production plants is not limited by the RTP, but rather by the maximum transport speed of substrates or the coating of the substrates.

According to an advantageous embodiment of the invention, at least one low-e layer contains or consists of silver. Thin silver films in a wetted configuration are transparent in the solar and / or visible spectral region and at the same time highly reflective in the infrared wavelength range. Conventionally, in the production process, thin silver layers usually can not be deposited in an ideal conformal manner and tend to become dewetting. This

results in a corrugated, not ideally uniform layer thickness distribution, which is very disadvantageous for heat-insulating coatings. By the subsequent

thermal treatment of the layer in the short-time annealing step By means of electromagnetic radiation due to the diffusion processes caused by the temperature increase takes place over the entire surface wetting and thus smoothing of the silver layers. However, it is conceivable that the low-emitting layer comprises or consists of other materials

Insofar as this is considered to be acceptable for low-e coating systems, low thermal emissivity in the infrared range with a high transmittance in the

have visible spectrum.

According to an advantageous embodiment of the invention, the substrate is made of glass as the main substrate used by low-e layer systems. The high absorption in the IR range loses due to the process control as

Short term tempering with limitation and possibly with

Monitoring of the layer and thus substrate temperature in importance.

In a further advantageous embodiment of the invention, in the step of forming at least one low-emitting layer, the method comprises a plurality of layers for forming a low-emittance layer system. In this case, the layers can be thermally treated by means of electromagnetic radiation in the short-time heat treatment step of the low-emittance layer and / or in a further short-time heat treatment step. Preferably, the low ^¬ emitting layer system comprising at least two dielectric layers. Preferably, a low-e silver layer is arranged between at least two dielectric layers.

In an advantageous embodiment of the invention, both the coating and the Kurzzeittemperschritt the deposited low-e layer by means of electromagnetic radiation in an inline vacuum coating system. With respect to the present invention, an "inline" Process management "a physical transport of the substrate from a coating station to another processing station to apply and treat layers, the substrate during the coating process

and / or the flash lamp irradiation is also transported. In this case, the substrate is preferably moved with such a transport speed that it does not heat up too much. The process may be operated in continuous flow systems with continuously-transporting substrate strip, either an endless substrate and a roll-to-roll coating, or a quasi-continuous sequence of synchronously moving, aufein ^¬ other following general cargo area substrates.

In an advantageous embodiment of the method, the short-time annealing step takes place in situ after the layer deposition of the substrate in the same treatment chamber.

In a further advantageous embodiment of the method, a further layer deposition is carried out after the thermal treatment of the low-e layer. Preferably, after the or each further low-layer deposition, a further thermal aftertreatment is carried out. In this case, the energy input in the thermal treatment is adjusted so that a predetermined final temperature of

treated low-e layer is obtained.

The inventive method is thus more energy efficient and associated with less breakage losses compared to conventional convection ovens. The color shift of the low emissivity layer system reached with the method is congruent to the values which are observed for konventi ^¬ onelles annealing, which equalizes visual differences, and the parallel assembly of both discs

allows. The object of the invention is based According to the invention also solved by the features of claim 10. Further embodiments of the invention will be apparent from the

the dependent claims. According to the invention, the device for

Implementation of the method according to the invention a flash lamp assembly for short time annealing of the low-e layer system. In this case, the flashlamp arrangement has at least one flashlamp, preferably a xenon lamp. With flash lamps can cost RTP plants of large areas at high throughput, z. B. greater than 40m ² / min to be built.

In an advantageous embodiment of the invention, the flash lamp assembly comprises a beam shaping device, for example a diaphragm or a mirror system, for

Generation of a linear intensity distribution of the electromagnetic radiation, which is advantageously perpendicular to the transport direction of the substrate. In this case, the length of the linear intensity distribution of the electromagnetic radiation for short-term etching corresponds at least to the width of the layer deposited on the substrate in the direction of the longitudinal extent of the linear intensity distribution of the electromagnetic radiation. As a result, areas of the low-emitting layer system in the longitudinal extent of the linear intensity distribution are simultaneously irradiated and cooled for a short time, which leads to a homogeneous structuring of the low-e coating in the irradiated area.

The invention will be explained in more detail below the embodiment. The accompanying drawings show: FIG. 1: a schematic representation of the system for the combined coating and subsequent thermal treatment by means of a flash lamp arrangement;

Transmission (Trans) and reflection spectra (Refl), measured from the glass or layer side, in each case before (untreated) and after the thermal treatment of the low-e layer by means of the flash lamp arrangement. The concrete details described below

Process steps and equipment are only to be understood as illustrative examples. The invention is therefore not limited to the process parameters, apparatus and

Limited materials.

Fig. 1 shows the basic structure of the system 1 for the combined coating and subsequent thermal treatment by means of a flash lamp assembly. It consists of an elongated vacuum system 1 with a

Substrate transport system 11, by means of which the large-area substrates 10 in a transport direction under different processing stations, u.a. Coating modules 30, are moved through. In a coating module 30, a low-e layer system 20 is applied to the substrate 10, which has at least one low-e layer. There are also several low-e layers conceivable.

After the coating has taken place, the substrate 10 provided with the layer system 20 is brought into a position for treatment with the flash lamp arrangement 50. In this case, the flash lamp arrangement has a plurality of flash lamps 53, in particular xenon lamps. The flashlamp arrangement 50 consists of a mirror system 52 which, by means of a suitable arrangement and geometry, projects the light of the flashlamps homogeneously onto the substrate 10 provided with the low-e layer system 20 from the layer side. A quartz glass plate 51 separates the flash lamp assembly 50 from the actual vacuum processing chamber. After the completed thermal

Treatment, the deposited substrate 10 can then be transported to another processing station 31 or the thermal treatment can be repeated. Optionally, the system 1 to a control 41 of the energy ^¬ entry of the heat treatment of the low-e layer system. The controlled variable corresponds to an energy input, which is necessary to obtain a predetermined final temperature of the low-e layer system in the subsequent step of the thermal treatment. In this case, the final temperature of the deposited layer system 20 within certain

Limits are achieved by adjusting and thus improving their layer properties, such as

Example transmission, reflection and resistance occurs, and not destruction of the structure, such as embrittlement, caused due to exceeding the maximum temperature of the deposited layer.

In this regard, the adjustment of the energy input of the irradiation both in consideration of the parameters of the electromagnetic radiation of the flash lamp device, such as their wavelength, energy density, exposure area, as well as the temperature of the deposited layer or. from the

Temperature of the deposited layer or the deposited layer system and the substrate. For this purpose, an arrangement of the temperature measuring means 40 in the system 1 and a temperature measurement before the short-term tempering step is conceivable.

The determined value of the energy input is determined by the

Control device 41 is transmitted to the flash lamp device 50 and serves as a controlled variable for determining the parameters of the Kurzzeittemperschritts and for carrying out the subsequent Kurzzeittemperschritts. This means that the parameters of the short-time annealing step, such as wavelength, duration, and type of electromagnetic radiation, are adjusted so that the layer system to be treated receives the determined energy input and thus the low-e layer reaches the predefinable end temperature. Exemplary embodiment:

A glass substrate having dimensions of 10x10 cm is introduced into a vacuum chamber and having a double temperable low-e (DLE) coated layer stack having a silver ^¬ layer between two dielectric layers. The sample represents a commercially available layer system. To improve the optical properties of the low-e layer stacks, it is irradiated with a xenon lamp device and an energy density of the radiation of 2 J / cm ² . The sheet resistance of the low-e layer stack before and after the irradiation is measured using an eddy current measuring device

determined, since the silver layer can not be contacted directly by the dielectric cover layers. The irradiation of the low-e layer stack results in a reduction of the surface resistance of the low-e layer from 6 ohm square (see reflection spectrum in FIG. 2) to 3 ohm square. The reduction in sheet resistance indicates compaction and homogenization of the silver layer, which is the characteristic feature of the expected improvement in emissivity.

FIG. 2 shows the respective transmission and reflection spectra of the sample. The term "trans" corresponds to the transmission spectrum of the sample before (untreated) and after the irradiation, and the formulation "Refl" to the reflection spectrum measured from the layer side before (untreated) and after the irradiation. The comparison of the spectra given results for the thermally treated sample a significant increase in the transmission in the visual spectral range and a favorable higher reflection in the infrared wavelength range. LIST OF REFERENCE NUMBERS

Coating plant system

substratum

transport system

Coating / layer

Coating module / coating station

Processing module / processing station

Means for temperature measurement

Flash lamp assembly

quartz glass plate

mirror system

flash lamp

Claims

claims

A method of making a low-emissivity layer system comprising the steps of forming at least one transparent metallic IR reflective layer, hereinafter referred to as low-emittance

Layer referred to, on at least one side of the substrate by means of deposition and subsequent brief annealing at least one deposited layer by means of electromagnetic ^¬ electromagnetic radiation while avoiding an immediate

Heating the substrate, characterized in that at least one low-emitting layer

short-term tempered, the electromagnetic

Radiation by a flash lamp assembly, which has at least one flash lamp, preferably a plurality of flash lamps, is carried out by at least one lightning pulse.

2. The method according to claim 1, characterized

characterized in that as a flashlamp a

Xenon flash lamp is used.

3. The method according to claim 1 or 2, characterized

characterized in that the flash lamp at a

Current density greater than 4000A / cm ^{2 is} operated.

4. The method according to any one of claims 1 to 3, characterized in that the duration of the flash pulses is set in the range between 0.05 to 20 ms.

5. Method according to one of the preceding claims,

characterized in that the

is set for short-term annealing electromagnetic radiation such that the low-emitting layer receives a predetermined energy input in the irradiation area.

6. Method according to one of the preceding claims,

characterized in that at least one low-emitting layer comprises or consists of silver.

7. Method according to one of the preceding claims,

characterized in that, in the step of forming at least one low-emitting layer, it comprises a plurality of layers to form a low-emittance layer system.

8. Method according to one of the preceding claims,

characterized in that the

low-emissivity coating system at least two

having dielectric layers.

9. Method according to one of the preceding claims,

characterized in that it takes place in an in-line vacuum coating system.

10. Apparatus for carrying out the inventive

Method according to one of claims 1 to 9, characterized in that it comprises a flash lamp arrangement for brief annealing at least one transparent

Metallic IR reflective layer of a low-emitting layer system, hereinafter referred to as low-emitting layer includes.

11. The device according to claim 10, characterized

in that the flash lamp arrangement has at least one flash lamp, preferably a xenon lamp.

12. Device according to claims 10 or 11, characterized in that the flash lamp arrangement comprises a beam shaping device for generating a linear intensity distribution of the electromagnetic radiation.

13. Device according to one of claims 10 to 12, characterized in that it comprises a means for controlling the energy input of the flash lamp assembly.

14. A low-emissivity coating prepared by the process according to any one of claims 1 to 9.