Method and apparatus for depositing organic layers

Abstract

The present invention relates to an apparatus for depositing organic layers on a substrate (16). The apparatus comprises one or more inlets (2, 2') for supplying gas streams (F1, F2) composed of pre-vaporized organic molecules, each having a molar mass greater than 300 g / mol or 400 g / mol, a gas mixing device (1), a gas diverter (7) for diverting the gas multiple times to homogenously mix the organic molecules in the carrier gas, and an outlet (8) from which the homogenous gas mixture is discharged. The apparatus also comprises a delivery pipe (9) connected to the outlet (8) and a gas inlet member (10) having a gas distribution space (11) into which the delivery pipe (9) is introduced. The gas distribution space has a gas outlet face (13') with gas outlet holes (12) and facing a substrate holder (15) for receiving a substrate (16). The present invention also relates to a method for depositing a layer on a substrate using such an apparatus. In order to improve the lateral uniformity of the deposited layer, the invention proposes that the mean flow velocity (Vm) in the conveying pipe (9) is selected so that the conveying pipe (9) has a diffusion influencing means (25) formed accordingly or a pressure barrier (20) is provided on the conveying pipe (9) at the end opposite the gas inlet element (10), whereby the segregation diffusion of organic molecules towards the center of the cross section of the conveying pipe (9), which would result in lateral non-uniform layer growth, is at least suppressed and preferably avoided in the conveying pipe (9).

Description

[Technical Field]

[0001] The present invention relates to a method for depositing a layer on a substrate, in which a gas stream consisting of pre-vaporized organic molecules of more than 300 g / mol or 400 g / mol carried by a carrier gas is supplied to one or more inlets of a gas mixer, the molecules of the one or more gas streams are diverted multiple times using a gas diverter to be uniformly mixed in the carrier gas, the mixture thus formed is discharged as a gas stream from the outlet of the gas mixer into a conveying pipe, transported by the conveying pipe to a gas distribution space of a gas inlet member, and exits through gas outlet holes of the gas distribution space towards a susceptor, and the molecules are deposited as an organic layer on a substrate received by a substrate holder.

[0002] The present invention further relates to an apparatus for carrying out the method, comprising a gas mixer in which a gas flow consisting of pre-vaporized organic molecules of more than 300 g / mol or 400 g / mol carried by a carrier gas is supplied to each of one or more inlets, a gas redirector which redirects the gas flows multiple times to mix them uniformly, an outlet from which the uniform gas mixture leaves, a transport pipe connected to the outlet, and a gas inlet member having a gas distribution space into which the transport pipe opens, the gas distribution space having a gas outlet surface with gas outlet holes, the gas outlet surface facing a substrate holder for receiving a substrate. [Background technology]

[0003] An apparatus for depositing layers on a substrate is shown in US Pat. No. 5,623,999, in which two different gases are mixed in a mixer and conveyed through a conveying pipe to a gas inlet element in the form of a showerhead. An apparatus for vaporizing an aerosol which is conveyed together with a carrier gas to the gas distribution space of a showerhead is known from US Pat. No. 5,623,999.

[0004] US Pat. No. 5,649,999 discloses an apparatus for generating steam, which is guided through a conveying pipe to a gas inlet member.

[0005] Large-area deposition of layers, particularly of organic materials, especially for OLEDs, is performed using a showerhead-shaped gas inlet element with a gas distribution space supplied by a transport pipe. A gas mixing system is used to mix a homogeneous mixture of vapors of molecules with a molar mass greater than 300 g / mol or greater than 400 g / mol, particularly ALQ3 molecules, with a carrier gas. The resulting gas flow is fed into the transport pipe. The gas flow from the transport pipe is distributed within the gas distribution space and exits the process chamber through gas outlet holes in a gas outlet plate. The gas outlet holes face the substrate on which the layer is to be deposited. In the prior art, the total pressure inside the gas distribution chamber or transport pipe, or the process chamber, is typically operated at approximately 1 mbar.

[0006] In experiments, lateral non-uniformity of layer growth or layer composition was observed when the total pressure inside the gas distribution chamber was reduced. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] German Patent Application Publication No. 102014106523 [Patent Document 2] German Patent Application Publication No. 102014109196 [Patent Document 3] International Publication No. 2012 / 175128 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a means by which the total pressure inside the process chamber and gas distribution chamber can be reduced to below 1 mbar without causing any observed lateral non-uniformities in the layer growth or layer structure. [Means for solving the problem]

[0009] This problem is solved by the invention as set forth in the claims, the dependent claims not only indicating advantageous further developments of the invention as set forth in each dependent claim, but also indicating independent solutions to the problem.

[0010] The present invention is based on the recognition that lateral nonuniformity is due to the separation of the supplied mixture within the transport pipe. As the mixture flows through the transport pipe, the concentration of vaporized molecules increases in the central region. A concentration gradient of large molecules forms from the center to the edges. This concentration gradient is due to diffusion perpendicular to the flow (cross-diffusion), which is caused by temperature nonuniformity within the cross section of the transport pipe. Parabolic flow is formed within the transport pipe, particularly in the region adjacent to the gas mixer. This results in local acceleration or deceleration of the gas. The local energy change associated with the gas flow occurs adiabatically, resulting in a decrease in the temperature in the region where the gas is accelerated. This is particularly true for the center of the gas flow, resulting in a temperature gradient that descends from the edges of the transport pipe toward the center. This is the cause of thermal diffusion (thermophoresis) of large organic molecules toward the center. Another reason for the separation toward the center may be the shear stress gradient of the flow, which decreases from the edges to the center of the transport pipe.

[0011] Studies, especially model calculations, have shown that the observed separation can be avoided if the flow velocity does not exceed an upper limit and / or if the ratio of the diameter of the conveying pipe to the mean velocity of the flow therein is equal to or greater than a lower limit. The Mach value of the mean flow velocity should, if possible, be less than 0.1. Therefore, the mean flow velocity should, in particular, be less than 40 m / s, 30 m / s, 20 m / s, or 10 m / s. The value of a function of the gas flow rate through the conveying pipe, the pressure in the conveying pipe, the temperature of the conveying pipe, and the diameter of the conveying pipe should be less than a limit value that depends on the maximum allowable non-uniformity in the deposited layer. The maximum non-uniformity of the layer (the ratio of the maximum deviation from the mean value to the mean layer thickness) should, for example, not exceed 0.5% or 1%.

[0012] To achieve this, a means for increasing the pressure in the conveying pipe is provided, in particular to a pressure in the region of 0.5 mbar or 1 mbar. A pressure barrier for achieving this is preferably arranged at the end of the conveying pipe, in particular within the gas distribution space. The pressure barrier can have an annular plate surrounding the space and provided with gas through-holes, into which the gas mixture conveyed through the conveying pipe is fed. The gas mixture enters the gas distribution space through the gas through-holes. The pressure barrier can have an annular body that surrounds the space enclosed by the bed and is provided with gas through-holes. In this case, the bed preferably does not have gas through-holes and faces the opening of the conveying pipe. Due to the pressure barrier, the pressure in the gas distribution chamber can be less than half, a quarter, or an eighth of the pressure in the conveying pipe, which can preferably exceed 1 mbar or 0.5 mbar, but preferably not less than 1 / 10 or 1 / 20 of the pressure in the conveying pipe. However, it is also possible to design the diameter of the conveying pipe to be correspondingly larger in order to set the flow rate or the above-mentioned ratio. Furthermore, in order to reduce or prevent the diffusion of large molecules in a direction transverse to the direction of flow, diffusion influencing means are provided. The diffusion influencing means may be physical barriers that separate the flow passing through the conveying pipe into a number of parallel, e.g. concentric, sub-flows. The diffusion influencing means may be tubes nested within one another and / or extend over the entire length of the conveying pipe.

[0013] The gas mixer has at least one inlet through which a mixture of organic vapors in a carrier gas is supplied. The gas mixer has multiple gas redirecting elements through which the gas flow is redirected multiple times, thereby forming the most complete mixture possible at the gas mixer outlet. It is particularly proposed that the gas mixer has two or more inlets through which a mixture of different organic molecules is supplied. Various organic molecules can be converted into vapor form by vaporizing solids or liquids. For this purpose, it is preferable to use an aerosol generator that generates a single aerosol in each case. The aerosol is transported to the vaporizer by a carrier gas supplied to the aerosol generator via a supply line, where the aerosol particles vaporize by moving in contact with a heat transfer surface. Different vapors are mixed in the gas mixer.

[0014] Studies, especially model calculations, have shown that for ALQ3 there is the following relationship between the non-uniformity and the average velocity in the conveying pipe:

[0015]

number

[0016] For ALQ3, a = 49.62 g m :Average layer thickness δg: Maximum deviation of layer thickness from the average value v m :Average velocity of gas flow in the conveying pipe

[0017] For the average value of the gas flow velocity in the conveying pipe, the following functional relationship is obtained:

[0018]

number

[0019] Q: Gas flow through the conveying pipe (sccm under standard pressure P0 and standard temperature T0) T: Temperature of the gas in the conveying pipe P: Pressure of gas in the conveying pipe d: diameter of conveying pipe C:1.5×10 7 ×π

[0020] Therefore, we obtain the following inequality:

[0021]

number

[0022] These and other embodiments of the present invention are described in more detail with respect to the following drawings. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic diagram of an embodiment of a longitudinal cross section of an apparatus according to the invention. [Figure 2] FIG. 2 is a partial view of FIG. 1 according to a second exemplary embodiment. [Figure 3] FIG. 3 is a partial view of FIG. 1 according to a third exemplary embodiment. [Figure 4] FIG. 4 is a schematic illustration of a parabolic velocity profile in the conveying pipe 9 . [Figure 5] FIG. 5 is a schematic diagram of the temperature distribution inside the conveying pipe 9. [Figure 6] FIG. 6 shows the effect of the pressure P3 inside the transport pipe 9 on the non-uniformity of the deposited layer. [Figure 7] FIG. 7 shows the influence of the average flow velocity inside the conveying pipe on the temperature gradient in the conveying pipe 9 (FIG. 5). [Figure 8] FIG. 8 shows the effect of the temperature gradient in the transport pipe 9 on the non-uniformity of the deposited layer. [Figure 9] FIG. 9 shows the effect of the average velocity of the gas flow inside the transport pipe 9 on the non-uniformity of the deposited layer. [Figure 10] FIG. 10 shows the influence of the ratio Q / P (mass flow / pressure) inside the transport pipe 9 on the non-uniformity of the deposited layer. DETAILED DESCRIPTION OF THE INVENTION

[0024] 1 shows a schematic diagram of a device according to the invention. The device according to the invention can have at least one organic vapor source. This source comprises an aerosol generator 4, by which aerosol particles are generated from a solid or liquid. The molecules of the aerosol particles have a molar mass greater than 300 g / mol or greater than 400 g / mol. Preferably, aluminum-tris(8-hydroxyquinoline), C 27 H 18 The organic compound is AlN3O3 and has a molar mass of 459.43 g / mol. In an exemplary embodiment, a source of several different organic molecules is provided. A carrier gas supply line 3 is provided, by which a carrier gas is supplied to an aerosol generator 4. The aerosol particles are transported via a heated aerosol line 5 to a vaporizer 6, where vaporization of the aerosol particles occurs under pressure P1 or P2. The vapor so produced is supplied to an inlet 2 of a gas mixer 1 through a heated line.

[0025] The gas mixer 1 has a mixing chamber maintained at a temperature above the condensation temperature of the organic molecules by a heating device 26. Inside the mixer 1, there is at least one redirecting path through which the mixture flows, which is supplied non-uniformly to the inlets 2, 2'. The flow of the mixture is redirected multiple times by the gas redirecting element 7, and by these redirections, a distribution of the organic molecules in the carrier gas as uniform as possible is achieved in the region of the outlet 8.

[0026] FIG. 1 shows diagrammatically that the cross section of the path travelled by the mixture through the gas mixer 1 decreases in the region of the outlet 8, thereby increasing the flow velocity of the gas stream.

[0027] The outlet 8 of the gas mixer 1 opens into a conveying pipe 9, which may be formed as a tube with a circular cross section. The conveying pipe 9 has a length of 10 to 20 cm. 2The conveying pipe 9 may have a cross-sectional area of ​​1000 . The conveying pipe 9 is temperature-controlled by a heating device 27 to a predetermined temperature, which may be the same as the temperature-controlled temperature of the gas mixer 1. However, the temperatures of both may also be different from each other. Inside the conveying pipe 9 there is a gas mixture at a pressure P3. In the exemplary embodiment, the conveying pipe 9 is arranged in a housing 17, in which the gas inlet member 10 is also arranged.

[0028] The conveying pipe 9 opens into the gas distribution space 11 of the gas inlet member 10. For this purpose, the gas inlet member 10 is provided with gas inlet openings 14, through which the gas mixture conveyed by the conveying pipe 9 can enter the gas distribution space 11. The floor of the gas distribution space 11 forms a gas outlet plate 13 with a gas outlet surface 13'. The gas outlet holes 12 are arranged in the gas outlet plate 13. The gas outlet holes 12 are uniformly distributed on the gas outlet surface 13'. The gas outlet holes 12 face towards a substrate 16 carried by a substrate holder 15. The substrate is cooled by a cooling medium flowing through the cooling medium channels 18, so that organic molecules can condense on the substrate 16. A heating device 19 is provided, which controls the temperature of the gas outlet plate 13 or the wall of the gas inlet member 10, in particular, at a temperature higher than the condensation temperature of the organic molecules.

[0029] FIG. 4 shows the velocity profile of the flow inside the conveying pipe 9. The velocity profile is parabolic. The flow velocity v is maximum in the center of the conveying pipe 9 and zero at the edges. When this flow is formed in the region of the outlet 8 of the gas mixer 1, the volume elements of the gas mixture accelerate or decelerate. The resulting adiabatic energy change within the volume elements results in a corresponding temperature change due to a lower total pressure or higher flow velocity, which can lead to a temperature decrease, especially in the center of the gas flow through the conveying pipe 9. This results in a temperature profile as shown diagrammatically in FIG. 5. Compared to the carrier gas, which can be nitrogen or hydrogen, the larger cross-sectional area of ​​the organic molecules leads to diffusion across the flow direction. The diffusion direction is radial, resulting in a separation from the edges to the center. In the region of the gas inlet opening 14, a higher concentration of organic molecules is present in the center of the gas flow than at the edges. In prior art devices or with process parameters used in prior art process controls, this non-uniformity is reflected in the distribution of the gas mixture in the gas distribution space 11, resulting in gas with different concentrations of organic molecules exiting at different locations through different gas outlet holes 12, which is reflected in non-uniformity of the layer growth. The effect of pressure and average velocity on the non-uniformity of the layer growth is shown in Figures 6 to 10.

[0030] To avoid this non-uniformity, one aspect of the invention provides that the flow velocity in the conveying pipe 9 is less than 40 m / s, less than 30 m / s, less than 20 m / s, or less than 10 m / s. Figure 9 shows the dependence of the layer non-uniformity, i.e., the ratio of the maximum deviation of the layer thickness from the average value to the average value of the layer thickness, as a function of the average flow velocity through the conveying pipe 9. The experiments carried out showed a non-linear behavior: the non-uniformity increases with an exponent of 1.572. The inverse function gives the critical average flow velocity, which depends on the desired level of non-uniformity (%) with an exponent of 0.636.

[0031]

number

[0032] Layer thickness non-uniformity (δg / gm ) can be maintained within an acceptable range by selecting the process parameters, Q: gas flow through the conveying pipe (in sccm at standard pressure P0 and standard temperature T0), T: temperature of the gas in the conveying pipe, P: pressure of the gas in the conveying pipe, and d: diameter of the conveying pipe, to satisfy the following inequality:

[0033]

number

[0034] In this case, a is 349.62 for ALQ3, but can be larger or smaller for other molecules, and C is 1.5 x 10 7 ×π.

[0035] The present invention further provides that the reduction in flow velocity is achieved by a pressure barrier 20. The pressure barrier 20 shown in FIG. 1 is an annular body 21 having a plurality of gas passage holes 22. Its floor 23 is spaced apart from the gas outlet plate 13 and may not have any gas passage holes. The floor 23 closes the inner space of the annular body 21. The pressure barrier 20 allows a pressure P3 inside the conveying pipe 9 to be 1 mbar or more, or 0.6 mbar, 0.5 mbar, or 0.3 mbar or more. Meanwhile, the pressure P0 inside the gas distribution space 11 can be significantly reduced. It can be less than 1 mbar, less than 0.6 mbar, or less than 0.3 mbar. The gas passage holes 22 can be arranged in an annular thin-walled plate, the thin wall of which bounds a space whose first end is closed by the floor plate 23 and whose second end opens into the conveying pipe 9.

[0036] The exemplary embodiment shown in Figure 2 shows a pressure barrier 20 formed by an open-pore foam. In the exemplary embodiment shown in Figure 1, gas passage holes 22 function as the pressure barrier. In the exemplary embodiment shown in Figure 2, it is the flow paths formed by the pores in the solid foam.

[0037] Figure 3 shows an alternative concept to solve the problem: a diffusion barrier 25 is provided, which prevents the above-mentioned cross-diffusion. It can be a concentric circular tube that separates the conveying pipe 9 into separate flow paths.

[0038] The diffusion influencing means 25 can extend over the entire length of the conveying pipe 9 and its diameter is in particular smaller than the average diameter of the flow paths in the gas mixer 1 and / or smaller than the cross section of the gas distribution space 11 .

[0039] In particular, it is intended and / or permitted that the gas flow leaving the gas mixer 1 is accelerated as it enters the conveying pipe, resulting in a lower gas temperature in the center of the gas flow. However, according to the invention, the temperature difference in the gas flow at the edges of the conveying pipe 9 is so small that non-uniform layer growth is avoided or limited to an acceptable minimum extent.

[0040] The measures described above do not allow 100% avoidance of temperature or shear gradients in the flow, but they do limit them to magnitudes that are no longer technically relevant, i.e. layers are deposited with non-uniformities below pre-specified limits, with technically acceptable results.

[0041] The foregoing serves to describe the invention encompassed by the application as a whole, which independently advances the prior art by at least the following combination of features, where any two, some, or all of these combinations of features may be combined:

[0042] The average flow velocity v in the conveying pipe 9 is at least suppressed and preferably avoided so that the segregation diffusion of the organic molecules in the conveying pipe 9 towards the cross-sectional center of the conveying pipe 9, which would result in laterally non-uniform layer growth, is at least suppressed and preferably avoided. m is selected in this way, or the conveying pipe 9 has a diffusion influencing means 25 configured in this way, or a pressure barrier 20 for this purpose is provided at the end of the conveying pipe 9 facing the gas inlet member 10.

[0043] The apparatus is characterized in that the conveying pipe (9) has such a cross-sectional area, or has diffusion influencing means (25) configured in such a way, or is provided with a pressure barrier (20) at its end opposite the gas inlet member (1) so that the separation diffusion of organic molecules towards the cross-sectional center of the conveying pipe (9), which would result in laterally uneven layer growth, is at least suppressed and preferably avoided.

[0044] A method or device characterized in that the pressure barrier 20 is in particular an annular throttle inside the gas distribution space 11 and / or is a plate provided with gas through holes 22 and extending in particular on a cylindrical circumferential surface and / or has an open-pore foam 24.

[0045] 10. A method or apparatus characterized in that the diffusion influencing means (25) comprise a barrier acting at least in the radial direction of the conveying pipe (9) and extending in the axial direction.

[0046] The total pressure P3 of the conveying pipe 9, the mass flow of the mixture through the conveying pipe 9, and the diameter D of the conveying pipe 9 are determined by the average flow velocity v m is selected to be less than 40 m / s, 30 m / s, 20 m / s, or preferably less than 10 m / s, and / or the total pressure P0 in the gas distribution space 11 is preferably less than 0.9 mbar, 0.6 mbar, 0.3 mbar, or 0.1 mbar.

[0047] The following inequality is satisfied with the following parameters, where a is a molecule-dependent value and is 49.62 M / s for ALQ3, and C = 1.5 × 10 7 ×π and ratio δg / g m is the maximum allowable non-uniformity, specifically the deviation of the layer thickness at any point in the layer from the average layer thickness, δg / g m is preferably 0.5% or 1%. Q: Gas flow through the transport pipe 9 (sccm under standard pressure P0 and standard temperature T0) T: temperature of gas in the conveying pipe 9 P: Pressure of gas in the conveying pipe 9 d: diameter of the circular equivalent cross section of the conveying pipe 9

[0048]

number

[0049] A method or apparatus comprising at least two vaporizers 6 for respectively vaporizing aerosol particles of organic molecules introduced into a carrier gas flow, characterized in that aerosol particles of different organic molecules are vaporized at different temperatures and / or at different total pressures and / or are supplied to different inlets 2, 2' of a gas mixer.

[0050] A method or apparatus characterized in that the gas mixer (1) has a first temperature control device (26) that controls the gas mixer (1) to a first temperature, and a second temperature control device (27) that controls the conveying pipe (1) to a second temperature.

[0051] All disclosed features are essential to the invention (not only on their own but also in combination with one another). The disclosure of any related / attached priority documents (copies of prior applications) is also fully incorporated into the disclosure of this application, with the aim of including the features of these documents in the claims of this application. Dependent claims are characterized by an independent, inventive further development of the prior art, even without the features of the claims to which they refer, in order to file a divisional application based on these claims, in particular. The invention specified in each claim may additionally have one or more features specified in the preceding description, in particular those given reference signs and / or specified in the sign explanations. The present invention also relates in particular to design forms in which some of the features mentioned in the preceding description are not implemented, insofar as they can be clearly omitted for the respective purpose of use or replaced by other technically equivalent means. [Explanation of symbols]

[0052] 1 Gas Mixer 2 entrance 2' entrance 3 Carrier gas supply line 4. Aerosol generator 5 Aerosol Line 6. Vaporizer 7 Gas diverter 8 exit 9. Conveying Pipe 10 Gas inlet member 11 Gas distribution space 12 Gas outlet hole 13 Gas outlet plate 13' Gas outlet surface 14 Gas inlet opening 15 PCB holder 16 boards 17. Housing 18 refrigerant channels 19 Heating device 20 Pressure Barrier 21 cyclic bodies 22 Gas passage hole 23 beds 24 Foam 25 Diffusion Barrier 26 Heating device 27 Heating device D diameter F1 gas flow F2 gas flow P0 pressure P1 pressure P2 pressure P3 Pressure v flow velocity v m average flow velocity

Claims

1. A method for depositing a layer on a substrate, comprising: one or more gas streams (F1, F2) of pre-vaporized organic molecules with a molar mass greater than 300 g / mol or 400 g / mol, carried by a carrier gas, respectively, being fed into each of one or more inlets (2, 2') of a gas mixer (1); the organic molecules of one or more of the gas streams (F1, F2) are diverted multiple times by a gas diverter (7) to be homogeneously mixed in the carrier gas; the gas mixture (F3) thus formed is led from an outlet (8) of the gas mixer (1) into a conveying pipe (9), conveyed through the conveying pipe (9) into a gas distribution space (11) of a gas inlet element (10), and discharged through gas outlet holes (12) of the gas distribution space (11) towards a susceptor; and the organic molecules are deposited as an organic layer on a substrate received by a substrate holder (15), The average flow velocity (v ) in the transport pipe (9) is set so that the separation diffusion of the organic molecules in the transport pipe (9) towards the cross-sectional center of the transport pipe (9), which would result in a lateral non-uniform layer growth, is at least suppressed or avoided. ｍ ) is selected in this way, or the conveying pipe (9) has diffusion influencing means (25) configured in this way, or a pressure barrier (20) is provided for this purpose at the end of the conveying pipe (9) facing the gas inlet element (10), the total pressure (P3) in the conveying pipe (9), the mass flow of the mixture through the conveying pipe (9) and the diameter (D) of the conveying pipe (9) are selected so that the mean flow velocity (v m ) is less than 40 m / s, 30 m / s, 20 m / s or less than 10 m / s; The method, characterized in that the total pressure (P0) in the gas distribution space (11) is less than 0.9 mbar, 0.6 mbar, or 0.1 mbar.

2. 2. The method of claim 1, wherein the aerosol particles of different organic molecules are vaporized at different temperatures or different total pressures.

3. 3. A method according to claim 2, characterized in that the aerosol particles of different organic molecules are fed into different inlets (2, 2') of the gas mixer.

4. 10. An apparatus for carrying out the method according to claim 1, comprising: a gas mixer (1) with one or more inlets (2, 2') for supplying gas streams (F1, F2) composed of pre-vaporized organic molecules with a molar mass greater than 300 g / mol or 400 g / mol, respectively, carried by a carrier gas; a gas diverter (7) in which the organic molecules are mixed in the carrier gas by multiple diverging; an outlet (8) from which a homogeneous gas mixture leaves; a gas inlet element (10) with a conveying pipe (9) connected to the outlet (8) and a distribution space (11) into which the conveying pipe (9) opens, the distribution space (11) having a gas outlet face (13') with gas outlet holes (12), the gas outlet face (13') facing a substrate holder (15) for receiving a substrate (16), The conveying pipe (9) a) has a cross-sectional area such that the flow velocity of the carrier gas nitrogen or hydrogen is less than 40 m / s to achieve a total pressure (P0) in the gas distribution space (11) of less than 0.9 mbar; b) comprising diffusion influencing means (25) for separating the flow through said conveying pipe (9) into a number of parallel partial flows, or c) at its end facing the gas inlet member (1), a pressure barrier (20) by which the pressure in the gas distribution space (11) is reduced to less than half the pressure in the conveying pipe (9), The cross-sectional area, the diffusion influencing means (25) and the pressure barrier (20) are configured to avoid segregated diffusion of organic molecules towards the cross-sectional center of the conveying pipe (9), which would result in lateral non-uniform layer growth.

5. 5. The device according to claim 4, characterized in that the pressure barrier (20) is an annular throttle inside the gas distribution space (11).

6. 5. The device according to claim 4, characterized in that the pressure barrier (20) is a plate provided with gas passage holes (22) and extending over the circumferential surface of a cylinder.

7. 5. The apparatus of claim 4, wherein the pressure barrier (20) comprises an open-pore foam (24).

8. 8. Apparatus according to any one of claims 4 to 7, characterized in that the diffusion influencing means (25) comprise a barrier acting at least in the radial direction of the conveying pipe (9) and extending in the axial direction.

9. 9. The apparatus according to claim 4, further comprising at least two vaporizers (6) for respectively vaporizing aerosol particles consisting of organic molecules introduced into a flow of carrier gas.

10. 10. Apparatus according to claim 9, characterized in that the aerosol particles of different organic molecules are fed into different inlets (2, 2') of the gas mixer.

11. 11. The apparatus according to claim 4, further comprising a first temperature control device (26) and a second temperature control device (27), wherein the gas mixer (1) is controlled to a first temperature by the first temperature control device (26) and the conveying pipe is controlled to a second temperature by the second temperature control device (27).

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