WO2012175307A1

WO2012175307A1 - Method and device for depositing oleds

Info

Publication number: WO2012175307A1
Application number: PCT/EP2012/060239
Authority: WO
Inventors: Michael Long; Markus Gersdorff
Original assignee: Aixtron Se
Priority date: 2011-06-22
Filing date: 2012-05-31
Publication date: 2012-12-27
Also published as: DE102011051260A1; JP2014523486A; KR102003527B1; KR20140053972A; JP6085595B2; TWI583809B; TW201305367A

Abstract

The invention first relates to a method for depositing an organic starting material as a layer on a substrate (18), wherein the organic starting material is introduced in the form of suspended particles in a carrier gas flow, the aerosol thus created is supplied as a predetermined mass flow of the organic material to an evaporator (5), which evaporator (5) comprises an evaporation body (6 - 10) which has a large surface and is heated to an evaporation temperature at which the suspended particles entering the vicinity of, or making contact with, the surface of the evaporation body (6 - 10) evaporate, the steam of the carrier gas flow thus created is introduced into a process chamber (17) where it condenses on the surface of a substrate (18), thus forming the layer. In order to make the steam inflow to the process chamber more uniform, according to the invention the mass flow of suspended particles to the evaporator (5) is greater than the evaporation rate of the suspended particles in the evaporator (5) such as to create a carrier gas flow saturated with the steam of the evaporated organic starting material to the process chamber, at least during one phase of the deposition process, in particular during a starting phase of the deposition process. The invention further relates to a device for depositing an organic starting material as a layer on a substrate.

Description

Method and device for depositing OLEDs

The invention relates to a method for depositing an organic starting material as a layer on a substrate, wherein the organic starting material is brought in the form of suspended particles in a carrier gas stream, the resulting aerosol is fed as dosed mass flow of the organic material to an evaporator, which evaporator evaporator body with has a large surface which is heated to an evaporation temperature at which the suspended particles passing into the vicinity of or in contact with the surface of the evaporation body evaporate, the vapor thus generated is brought from the carrier gas stream into a process chamber where it deposits on the surface of a substrate Layer forming condensed.

The invention further relates to a device for separating an organic starting material as a layer on a substrate, with an aerosol generator for generating a metered mass flow of the starting material in the form of suspended particles transported in a carrier gas stream to an evaporator, wherein the evaporator has open-pore evaporation body with a formed as a blind bore inlet channel, which evaporation body can be heated to an evaporation temperature to evaporate the suspended particles, with a process chamber for receiving the substrate, which is supplied to the steam generated by the evaporator through a steam supply line. A generic method or a generic device describes the US 7,238,389. By means of an aerosol generator, a pulverulent solid is brought into a carrier gas stream. The resulting aerosol particles become suspended particles in the carrier gas stream. Transported nem evaporator. The evaporator consists of a solid state foam, which is heated to an evaporation temperature. By a surface contact of the suspended particles with the pore walls of the solid state foam heat of evaporation is supplied to them, so that they are converted into the vapor form. The vapor thus generated is fed by means of the carrier gas stream into a process chamber in which there is a substrate which is coated with the organic starting material. The organic starting materials described in the document, which are also used in the process according to the invention in the device according to the invention, are organic light-emitting material, so that OLEDs can be produced, as described, for example, in US Pat. Nos. 4,769,292 and 4,885,211.

US 2006/0115585 A1 describes a device for depositing organic layers on a substrate with a heating device for heating the organic material so that an aerosol is formed in a carrier gas. The solid aerosol is passed over a nozzle having micropores, which has a Pulsheizeinrichtung, with which the organic particles can be heated. The micropores have a diameter of up to 100 μιη.

DE 10057491 A1 describes a device with which an aerosol is generated by injecting droplets into a hot gas volume and evaporating the droplets by absorbing heat. WO 2006/100058 describes a heating device with which a non-gaseous starting material can be converted into the gas phase, wherein the heating body is provided with cavities which have an inner surface. US 2006/0169201 A1 describes a generic device with a plurality of evaporation bodies arranged one behind the other in the flow direction and having channels running in the direction of flow and having a honeycomb-shaped cross-section. Through these channels flows to be vaporized particles carrying carrier gas flow. As a result of the rectilinear course of the channels having a honeycomb-shaped cross-section, a multiplicity of particles pass through the evaporation bodies without making contact with the wall of the channels. The use of a solid-state foam, in particular of tungsten, rhenium, tantalum, niobium, molybdenum or carbon or of a coated material for evaporating an organic starting material, also describes US 2009/0039175 A1 or US Pat. No. 6,037,241. The solid-state foam is heated there in particular by passing an electric current to an evaporation temperature at which the organic starting material evaporates.

From DE 10 2006 026 576 AI a solid-state evaporator is also known, in which the aerosol is generated by an ultrasonic exciter by the Aufwirbe- a powder. Although solid-state evaporators in which a large amount of starting materials to be evaporated are permanently maintained at an evaporation temperature, provide a continuous evaporation rate. However, there is a high risk that disintegrate in particular to be evaporated organic starting materials at high temperature. To counteract this problem, US 2009/0061090 AI or US 2010/0015324 AI suggest refillable evaporation containers in an evaporator. No. 7,288,286 B2 describes a screw conveyor in order to bring in a storage container stored powdered organic starting material in a gas stream which transports the powdery suspended particles to an evaporator.

An alternative method for producing powdery suspended particles is described in US Pat. No. 5,820,678. There, a brush wheel is described, which removes powder particles formed in the micrometer diameter range from a solid formed from a pressed powder. These powder particles are fed by means of a gas stream to an evaporator.

Aerosol generators are also known with which liquid starting materials, in particular organic starting materials for a MOCVD process, are brought in the form of droplets into a carrier gas stream. Related devices are described in US 2005/0227004, US 2006/0115585 and US 5,204,314. While the starting materials used for conventional MOCVD are generally liquid at room temperature or elevated temperatures, the organic starting materials to be used for the preparation of OLEDs are all solids below temperatures of 200 ° C.

In the known aerosol generators, there is some dependence in the steam generation rate on the suspended particulate generation rate in the aerosol generator. If, for example, a brush arrangement is used as the aerosol generator in which particles are removed from a pressed solid powder by means of a moving, in particular rotating brush, then the temporal aerosol formation rate depends on the shape of the brushes. Other known Aerosol generators have delivery devices for the starting material to be atomized into a carrier gas stream, whose delivery rate fluctuates over time.

If liquid starting materials are used, nozzles can be used for aerosol formation. Again, a temporal fluctuation of the aerosol production rate can not be prevented in principle.

The invention is therefore based on the object to provide measures to equalize the flow of steam to the process chamber.

The object is achieved by the invention specified in the claims.

First and foremost, it is proposed that the generated vapor in the carrier gas flow from the steam generator to the process chamber has a saturation vapor pressure. To achieve this, measures are taken with which there is an excess of unvaporised starting material in the evaporator during the entire deposition process. In order to generate a carrier gas stream saturated with the vapor of the vaporized organic starting material to the process chamber, in at least one phase, preferably an initial phase of the deposition process, the mass flow of the organic starting material to the evaporator, ie the mass of the suspended particles per unit time fed to the evaporator to the evaporator than the evaporation rate, So the per unit time converted into steam mass of the starting material in the evaporator. As a result, a storage mass of unevaporated organic starting material in the evaporator accumulates within an enrichment phase. The enrichment is preferably carried out in the cavity volume of the solid body foam used as the evaporation body. For this purpose, an open-pore foam body is used as the evaporation body. det, whose pore size is significantly greater than the size of the suspended particles. A typical measure of the diameter of a suspended particle is about 100 μπι. An average measure of the width of a pore opening is about 1 mm. The pore size can also be in the range of 0.5 mm to 3 mm. The cross-sectional area of the pores should preferably be greater than 1 mm ² . The pores are uneven, strongly curved, so that the carrier gas passing through the pores is deflected repeatedly and particles transported therein hit the pore walls. The solid state foam used can have a pore volume of more than 90 percent of its total volume. Favor is the evaporation of the aerosol in phases with different feed rate of the evaporator with suspended particles. In an enrichment phase, the evaporator is supplied with more mass of organic starting material over time than is evaporated there in the same time. This leads to the structure already mentioned above of a storage mass within the pore volume of the evaporation body. In a depletion phase subsequent to the enrichment phase, the feed rate of organic feedstock to the evaporator is reduced so that less material than suspended particulates is fed to the evaporator than is vaporized there at the same time. As a result, the storage mass is reduced in the course of the depletion phase. To ensure that a vapor-saturated carrier gas stream leaves the vaporizer for the entire deposition process, the depletion phase is terminated by switching to the enrichment phase, that is by increasing the supply of material before the storage mass has been consumed.

The device according to the invention may have an aerosol generator which has a time-varying generation rate of suspended particles. The suspended particles may be powdery or liquid. The aerosol Producer has a reservoir in which the organic source material is stored. The aerosol generator further has a doser, with which the production rate of the suspended particles can be influenced. According to the invention, the evaporator is developed to the effect that the evaporation body is multipartite. The known from the prior art, for example from US 2009/0039175 AI ago inlet channel in a porous evaporation body is inventively formed by a through hole of a first evaporation body. One or more such first evaporation body may be arranged in a row one behind the other. One of the ends of the through-hole is closed by a second evaporating body having substantially the same characteristics as the first evaporating body. This prevents that not vaporized suspended particles are transported through the evaporator. The gas stream introduced into the inlet channel and transporting the suspended particles can enter the porous volume of the first vaporization body through the walls of the inlet channel. A partial flow may enter the second evaporation body through the bottom of the inlet channel. The two evaporation bodies are preferably arranged one behind the other in the flow direction such that the gas emerging from the first evaporation body must also pass through the second evaporation body. The second evaporation body can be designed in several parts. Thus, a plurality of second evaporation bodies are formed, which preferably fully fill a cross-sectional area of the evaporator. In the current direction, the preferred plurality of second evaporation body may be followed by a third evaporation body, which has substantially the same material properties as the other evaporation bodies. The third evaporation body can have the same shape as the first evaporation body, so that an outlet channel is formed by it. The third evaporation Fung body can be designed in several parts. The first evaporation body and the third evaporation body have a through hole. The through holes may be in alignment with each other. They can be the same diameter. But it is also envisaged that the diameters of the through holes differ from each other. Thus, the holes within the evaporation body can also be stepped down. Furthermore, the evaporation bodies can also be arranged inside the evaporator in such a way that closed inner cavities are formed both in the inlet direction and in the outlet direction. Further, one of the evaporation bodies can extend only over a length which is of the order of the pore diameter, so that such an evaporation body acts as a diffuser. The outlet channel is preferably formed by a passage bore of the third evaporation body. The bottom of the exit channel is formed by the second evaporation body. The gas flowing through the one-piece or two-part second evaporation body can thus flow partly into the pore volume of the third evaporation body or partly into the outlet channel. Downstream of the third evaporation body extends a free volume whose cross-section may possibly decrease and which opens into a steam supply line through which the carrier gas flows together with the transported from him steam of the organic starting material in the process chamber. The steam supply leads there into a gas distributor, which has the shape of a shower head. A gas outlet surface of the gas distributor points in the direction of a susceptor, on which the substrate to be coated rests. Due to the large number of gas outlet openings arranged in the gas outlet surface in the manner of a sieve, the carrier gas transporting the vapor flows into the process chamber. The susceptor is preferably cooled so that the vapor can condense on the substrate. The process takes place at a taldruck instead, which takes place in the range between 0.1 and 100 mbar, preferably in a range between 0.1 and 10 mbar. To generate this negative pressure, the process chamber is connected to a vacuum pump. The evaporation bodies formed by a solid-state foam are arranged in a housing of the evaporator such that the aerosol provided in excess does not flow through the evaporation bodies. The aerosol units move rather on the surface of the pores and form there a supply. This ensures that despite the formation of a saturation vapor pressure downstream of the evaporation body no suspended particles are present in the downstream gas flow. In order to heat the evaporation body to the evaporation temperature, for example a temperature between 300 ° C and 400 ° C, the evaporator housing may be surrounded by a heater. Preferably, however, or consist of the evaporation body made of an electrically conductive material, so that an electric current can be passed through the evaporation body, which heats it. A temperature control device is provided to keep the temperature of the evaporation body constant, since the evaporation rate does not depend linearly on the evaporation temperature. In a variation, it is provided that in the open-pore foam body, be it made of glassy carbon, metal, ceramic, glass or quartz or coated, the surface of the cell walls is coated with a highly reflective material, especially gold.

Layers or layer structures can be deposited with the device according to the invention, as described in detail in the cited US Pat. No. 7,238,389 B2 and in the literature cited therein. Reference is therefore made in full to the disclosure content of these publications. Embodiments of the invention are explained below with reference to attached figures. 1 shows the schematic structure of a charging device,

2 shows a section along the line II - II in Figure 1,

Fig. 3 is a section along the line III - III in Figure 1 and

4 shows a section along the line III of a second embodiment,

5 is a sectional view of a second embodiment of an evaporator,

6 is a section along the line VI - VI in Figure 5,

7 shows a section according to the line VII-VII in FIG. 5, FIG. 8 shows a section according to the line VIII-VIII in FIG. 5.

From an unrepresented gas source, an inert carrier gas, for example nitrogen, hydrogen, or a noble gas is introduced into a carrier gas supply line 1 via mass flow controllers, likewise not shown. The Trägergaszulei- device can be heated so that a heated carrier gas can flow through the carrier gas inlet into an aerosol generator 3. In a storage container 2, an organic starting material is stored. It is an organic, by applying an electrical voltage light-emitting material with which light-emitting layers can be deposited on a substrate 18.

The aerosol generator 3 may be a brush wheel atomizer or else a screw arrangement, as described, for example, in US Pat. No. 7,501,152 B2 or in US Pat. No. 7,288,285 B2. With such an aerosol generator components of a powder can be introduced as suspended particles in a carrier gas stream. The time mass input rate of the suspended particles in the carrier gas flow, so the aerosol production rate can be varied.

The aerosol generator is connected to an evaporator 5 via an aerosol feed line 4. Through the aerosol feed line, the suspended particles are conducted into the evaporator 5 by means of the carrier gas flow.

The evaporator 5 illustrated in FIGS. 1 to 3 has a housing 11 and a heater 12 surrounding the housing 11. Within the housing is a multipart evaporation body 6 - 10, which is formed by a solid-state foam. The solid-state foam is brought to an evaporation temperature by means of the heater 12, so that the organic suspended particles coming into contact with the solid surface are vaporized.

The thus formed steam is passed through a steam supply line 13 with the aid of the carrier gas in a reactor housing 15. In order to prevent condensation of the steam on the walls of the steam supply line 13 or on the wall. to avoid the one in the reactor housing 15 arranged gas distributor 16, the gas distributor 16 and the steam supply line 13 is heated. The steam supply line 13 may, for example, have a heating sleeve 14. The disposed within the reactor housing 15 gas distributor 16 has a shower head-like shape. It is a disk-like hollow body with a gas outlet surface which points toward a process chamber 17 and has a multiplicity of gas outlet openings arranged in a sieve-like manner, from which the carrier gas stream carrying the steam flows into the process chamber 17.

While the gas outlet surface of the gas distributor 16 forms the ceiling of the process chamber 17, a susceptor 19, on whose surface facing the gas distributor 16 the substrate 18 to be coated is located, forms the bottom of the process chamber 17.

The susceptor 19 has a cooling means, not shown, with which its surface can be cooled, so that the substrate 18 can be maintained at a temperature at which the vapor of the organic starting material can condense on the substrate surface.

In the schematic drawing, valves and other gas lines that serve to rinse the process chamber are not shown. Also shown only schematically is a vacuum pump 20, by means of which the process chamber 17 and the evaporation chamber of the evaporator 5 can be kept at a low pressure. In a variant shown only in cross section in FIG. 4, the evaporation bodies 6 - 10 arranged in the evaporator 5 consist of an electrically conductive material. It is an open-celled solid state foam with a pore volume of about 97 percent of the total volume. The evaporation bodies have electrical contacts 21, 22, so that in each case an electrical current can be passed through the evaporation bodies 6 - 10, which heats the evaporation bodies 6 - 10 to vaporization temperature. The evaporation body 6 - 10 may consist of graphite or metal. If the evaporation bodies consist of non-conductive material, for example of a ceramic material, the evaporation bodies 6 - 10 are heated with the heating jacket 12 shown in FIGS. 1 to 3, which surrounds the tubular housing of the evaporator 5.

Within the tubular evaporator housing 11 is a first tubular evaporation body 6, which has a through hole 6 '. The through-bore 6 'is aligned with the aerosol feed line 4, so that the aerosol stream entering the evaporator 5 from the aerosol line 4 flows into the cavity of the first evaporation body 6. This inlet channel 6 'is surrounded by the porous wall of the evaporation body 6. The pore size of the evaporation body 6 is greater than the suspended particle size, so that the suspended particles can be introduced from the gas stream into the evaporation body 6, as illustrated by the arrows in the figure. The suspended particles, which come into contact with the hot surface of the pores of the evaporation body 6, partially evaporate. In some cases, the suspended particles are also stored in the pores of the evaporation body 6, provided that the aerosol is offered in excess. The gas stream or the suspended particle stream exits from the passage opening 6 'or from the volume of the first evaporation body 6 and in a second evaporation body 7, which adjoins directly to the first evaporation body 6. Three disc-shaped second evaporation body 7, 8, 9 are arranged one behind the other in the flow direction. The second evaporation bodies 7, 8, 9 completely fill the cross-sectional area of the tubular housing 11. They are touching each other. Downstream of the second evaporation body designated by the reference numeral 9 is a third evaporation body 10, which, like the first evaporation body 6, has the shape of a pipe. It has a passage opening 10 'aligned with the passage opening 6' of the first evaporation body 6 but separated from the second evaporation body 7, 8, 9, which forms an outlet channel. At the rear of the third evaporation body 10 there is a free volume, which merges into the steam supply line 13.

The evaporation body 6 - 10 are made of the same material and are able to temporarily store non-vaporized suspended particles as storage mass.

With the described device, the following inventive method is performed. A substrate 18 resting on the susceptor 19, which may be made of glass, is coated with the organic starting material. For this purpose, an aerosol mass flow to the evaporator 5 is initially generated in an enrichment phase of the aerosol generator 3, which is greater than the evaporation rate within the evaporator 5 for generating a vapor saturated carrier gas stream through the steam supply line 13 to the process chamber 17. As a result, this oversupply forms of suspended particles within the pores of the evaporation body 6 - 10 a storage mass. The size of the storage mass of unvaporized starting material increases during the enrichment phase. The enrichment phase is followed by a depletion phase, which differs from the enrichment phase essentially only by the rate of generation of the aerosol generator 3. During the depletion phase, the aerosol generator 3 generates a mass flow of suspended particles to the evaporator 5 which is lower than the evaporation rate, that is to say the mass evaporated per unit time, within the evaporator 5 for producing a vapor-saturated starting gas stream. In the course of the depletion phase, the storage mass decreases. Nevertheless, the vapor pressure of the vaporized organic starting material does not change within the gas flow conducted to the process chamber 17. This gas stream is permanently saturated with vaporized organic starting material. The vapor can condense on the substrate. However, it can also react chemically in the process chamber or on the substrate.

It is switched from the depletion phase in the enrichment phase, as long as there is still a storage mass within the evaporator 5.

During a coating process, it is possible to switch back and forth several times between the depletion phase and the enrichment phase.

Figures 5 to 8 show a second embodiment of an evaporator 5, as it can be used in a device shown in the figure 1. The aerosol feed line 4 continues within the tubular housing 11 for a few millimeters and thereby engages in a passage opening 6 "of a first evaporation body 6. This evaporation body 6 is spaced from the side wall of the housing 11 by an optional free space 24. The clearance 24 serves in FIG Essentially the heat insulation. A second through-opening 6, which has a diameter approximately twice as large, adjoins the through opening 6 ", which has a small diameter, and a further evaporation body 23, which likewise has a through-opening 23 ', is located downstream of the evaporation body 6. The through-opening 23' is aligned Downstream of the evaporation body 23 is a cross section of the tubular housing 11 fully filling the diffuser 7. This diffuser 7 is also essentially a vaporization body, since the diffuser 7 is made of the same material, from which also the other evaporation bodies 6, 23, 10, 8 and 9 consist, namely an open-cell foam body as already described above The thickness of the diffuser 7, ie its length measured in the direction of flow, is of the order of magnitude the opening width of the pores of the Diffusers 7.

Downstream of the diffuser 7 is followed by a further evaporation body 10, which has a first passage opening 7 ', which has the same diameter as the passage opening 6' and 23 '. A further, diameter-reduced through-opening 7 "adjoins this through-opening 7 'in the flow direction. The bottom of the through-opening 7" is closed, so that this is a blind opening. The bottom of the bag opening 7 "is formed by an evaporation body 8, the

Full diameter of the tubular housing 11 fills. The evaporation body 7 and the evaporation body 8 together with the evaporation body 10 form an on all sides closed inner cavity 7 ', 7 ". The evaporation body 8 is followed by an evaporation body 9, which is of substantially the same shape as the evaporation body 8. All evaporation bodies 6, 23, 7, 10, 8, 9 lie in a row in contact with each other in a row. In the direction of flow after the last evaporation body 9 is a free space 25. The space is in the steam supply line 13 via. Through the aerosol feed line 4, a carrier particle stream carrying suspended particles is introduced into the passage openings 6 ', 23'. The suspended particles pass with the gas flow into the walls of the passage openings 6 ', 23', ie into the open-cell evaporation body 6 and 23.

Suspended particles of relatively high mass and high velocity, ie those which carry a relatively large momentum, can reach the evaporation body 7. This acts as a diffuser and brakes the carrier gas flow and thus the suspended particles transported in it. If these suspended particles enter the cavity 7 ', 7 ", they enter the evaporation body 10 or 8, where they evaporate due to the absorption of heat.

The evaporation body described above can be an open-pore foam body made of glassy carbon or glassy carbon. The foam body may be coated with a metal or ceramic. The foam body may also consist of glass or quartz. In a particularly preferred embodiment, the surface of the foam body has a low optical emissivity. This is preferably less than 0.2 in the infrared range (200 to 400 ° C). The low surface emissivity is preferably achieved by gold-coating the cell walls. All disclosed features are essential to the invention. The disclosure of the associated / attached priority documents (copy of the prior application) is hereby also incorporated in full in the disclosure of the application, also for the purpose of including features of these documents in claims of the present application. The subclaims characterize in their optional sibling version independent inventive development of the prior art, in particular to make on the basis of these claims divisional applications.

LIST OF REFERENCE NUMBERS

1 carrier gas supply line 22 electrical contact

2 organic source container 23 evaporator body 3 aerosol generator 23 'through-hole

4 aerosol supply line 24 free space

5 evaporator 25 free space

6 evaporation body

6 'passage opening

6 "passage opening

7 evaporation body

7 'passage opening

7 "passage opening

8 evaporation body

9 evaporation body

10 evaporation body

10 'passage opening

11 tubular housing

12 heating

13 steam supply

14 heating

15 reactor housing

16 gas distributor

17 process chamber

18 substrate

19 susceptor

20 Vacuum pump

21 electrical contact

Claims

1. A method for separating an organic starting material as

Layer on a substrate (18), wherein the organic starting material is brought in the form of suspended particles in a carrier gas stream, the aerosol thus generated is supplied as a predetermined mass flow of the organic material to an evaporator (5), which evaporator (5) an evaporation body (6 10) having a high surface area which is heated to an evaporation temperature at which the suspended particles passing close to or in contact with the surface of the evaporation body (6 - 10) evaporate, the vapor thus generated from the carrier gas flow into a process chamber (17). where it condenses forming the layer on the surface of a substrate (18), characterized in that for generating a saturated with the vapor of the vaporized organic starting material carrier gas stream to the process chamber, at least in one phase of the deposition process, in particular in an initial phase of the deposition process the mass flow of suspended particles to the evaporator (5) is greater than the evaporation rate of the suspended particles in the evaporator (5).

2. The method according to claim 1 or in particular according thereto, characterized in that the size of the suspended particles is smaller than the pore size of an open-cell foam body having evaporator body (6 - 10).

3. The method according to one or more of the preceding claims or in particular according thereto, characterized in that in ab- alternating phases of the deposition process, the mass flow of the organic starting material to the evaporator (5) is varied such that in an enrichment phase, the time mass flow of the organic starting material to the evaporator (5) is greater than the mass flow of steam generated at the same time by evaporation of the organic starting material and in a depletion phase, the mass flow of the organic feedstock to the evaporator (5) is slightly less than the mass flow of the steam generated at the same time by evaporation of the organic feedstock, being changed from the depletion phase to the enrichment phase during the separation process, prior to any settling during the separation process Enriching phase in the evaporator enriched storage mass of the organic starting material is completely evaporated.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that as carrier gas in particular a preheated inert gas, in particular nitrogen, hydrogen or a noble gas, in particular argon, is used.

Method according to one or more of the preceding claims or in particular according thereto, characterized in that the evaporation takes place at a total pressure in the range between 0.1 and 100, preferably between 0.1 and 10 mbar.

6. The method according to one or more of the preceding claims or in particular according thereto, characterized in that the open-pore foam body consists of glassy carbon or of glassy carbon and with a metal, in particular tantalum, molybdenum, tungsten, rhenium, niobium or ceramic, in particular with silicon carbide or boron nitride or of metal, in particular tantalum, molybdenum, tungsten, rhenium or niobium or of ceramic, of glass or is made of quartz and / or optionally coated with another metal, such as gold.

Method according to one or more of the preceding claims, characterized in that the foam body has a pore width of more than 0.5 mm, preferably of more than 1 mm.

Apparatus for separating an organic starting material as a layer on a substrate (18), comprising an aerosol generator (3) for generating a metered mass flow of the starting material in the form of suspended particles transported in a carrier gas stream to an evaporator (5), the evaporator (5 ) open-pore evaporation body (6 - 10) having a formed as a pocket cavity inlet channel (6 '), which evaporation body (6 - 10) can be heated to an evaporation temperature to vaporize the suspended particles, with a process chamber (17) for receiving the substrate ( 18) supplied to the vapor generated by the evaporator (5) through a steam supply line (13), wherein the evaporation body (6 - 10) a first, with a through bore the inlet channel (6 ') forming the first evaporation body (6) and a second , the closed end (7 ') of the inlet channel (6') forming evaporator body (7) to prevent the passage nic Ht vaporized suspended particles, characterized in that the evaporation body (6 - 10), an open-pore Foam body is with a pore cross section of more than 1 mm ² and a pore volume of at least 90 percent of the total volume.

Apparatus according to claim 7 or in particular according thereto, characterized by a plurality of evaporation bodies (6 - 10) arranged one behind the other in the flow direction, one or more first evaporation bodies (6) with a through-hole of the same or a different diameter forming the inlet channel, one or a plurality of second evaporation body (7, 8, 9) the flow cross-section of the evaporator (5) fully filling in the flow direction behind the one or more first evaporation body (6) are arranged.

Device according to one or more of claims 7 to 8 or in particular according thereto, characterized by a third evaporation body (10) which forms an outlet channel (10 ') aligned in particular with the inlet channel (6'), the closed end (9 ') of which one or more second evaporation bodies (7, 8, 9) is formed.

Device according to one or more of claims 7 to 10 or in particular according thereto, characterized in that the steam supply line (13) in a reactor housing (15) arranged gas distributor (16) opens, the gas outlet surface has a plurality of sieve-like gas outlet openings and the one Substrate (18), in particular a cooled susceptor (19). lies opposite.

Device according to one or more of claims 7 to 11 or in particular according thereto, characterized in that the evaporator (5) has a heater (12) or that the evaporation body (6 - 10) consists of an electrically conductive material, by means of a through the Evaporating body (6 - 10) conducted electricity is electrically heated.