Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
  • C23C14/12—Organic material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/24—Vacuum evaporation
  • C23C14/246—Replenishment of source material
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/54—Controlling or regulating the coating process
  • C23C14/542—Controlling the film thickness or evaporation rate

Definitions

• the invention relates to a method for generating a vapor flow that is constant over time within specified tolerances, in which a metering device, in which a mass flow of a powder that is dependent on a setting value of a metering element, is generated and is conveyed into an evaporator, where it is Evaporation temperature is vaporized and from which it is conveyed with a carrier gas through a vapor discharge line, the metering device being operated in a vapor generation phase at an operating point defined by a setting value of the metering element and an evaporation temperature of the evaporator.
• the invention also relates to a method for adjusting the working point of a device for generating vapor using such a method, the working point being characterized, for example, by the parameters of the speed of the dosing element and the evaporation temperature of the evaporator.
• the invention also relates to a device for carrying out the method, with a dosing device that generates a mass flow of a powder dependent on a setting value of a dosing element, with a mass flow controller for providing a carrier gas flow for transporting the gas delivered by the dosing device Powder as an aerosol to an evaporator, which has evaporation surfaces that can be heated to an evaporation temperature, with a vapor discharge line for discharging the im Evaporator generated vapor by means of the carrier gas and with a control device.
• DE 10 2011 051 260 A1 describes a method and a device for generating a steam flow.
• the device has a dosing device and an evaporator.
• the metering device delivers an aerosol of a solid to be vaporized or a liquid to be vaporized.
• the aerosol flow rate can be adjusted by a delivery rate of a metering element of the metering device.
• the aerosol particles are evaporated with the evaporator.
• the method is carried out in such a way that in a first phase, with a high set value for the flow rate of the dosing element, a greater mass flow of organic material is conveyed into the evaporator than steam has left the evaporator, so that a storage mass accumulates in the evaporator.
• a mass flow of the organic material is fed to the evaporator that is lower than the mass flow of the vapor discharged from the evaporator.
• a method and a device for generating a vapor flow that is constant over time is described in DE 102014 102484 A1.
• a dosing device generates a temporally constant flow of a powder within specified tolerances, which is transported as an aerosol to an evaporator by means of a carrier gas.
• the vaporizer is operated at a vaporization temperature that is lower than the decomposition temperature of the organic powder but high enough to vaporize the powder.
• the powder is combined with a carrier gas through a vapor discharge to form a Reactor transported, which has a heated gas inlet element into which the steam is fed.
• the gas inlet element has gas outlet openings arranged like a shower head, through which the vapor flows into a process chamber in which a substrate to be coated is located.
• the substrate lies on a cooled substrate holder so that the vapor condenses on the surface of the substrate.
• Thin layers for the production of OLEDs are deposited with the device or the method. Typical deposition times in which steam is fed into the process chamber during a steam generation phase are in the range from a few seconds to a few minutes. In order to obtain a layer thickness that is as reproducible as possible, the steam flow, i.e. the mass flow of the steam to the reactor, must be kept constant over time within narrow tolerances.
• the mass flow of the vapor is largely determined by the mass flow of the powder (aerosol flow).
• the evaporation temperature also has an influence on the steam flow, since the steam generation rate is temperature-dependent to a certain extent.
• the rate of vapor production depends on the evaporating temperature, but is largely independent of the aerosol flow. In this range, the vapor generation rate is largely independent of the aerosol flow.
• the aerosol flow is too high, a mass of unevaporated material collects in the evaporator.
• DE 10 2017106 968 A1 discloses a sensor with which the vapor of a vapor flow in a vapor discharge line can be measured.
• WO 2012/175126 A1 describes devices and methods in which an organic material is transported as an aerosol and vaporized by means of a heated solid foam.
• the solid foam can also be used as a storage medium for the organic material.
• a dosing device is described, for example, in DE 10 2019110 036 A1 or in DE 102017106500 A1.
• a dosing device has a movable dosing element, in particular rotatable about an axis of rotation, with dosing chambers arranged uniformly about the axis of rotation, with which powder is transported from a powder supply to a delivery point.
• a dosing device can also be a screw conveyor.
• the powder is conveyed out of the dosing chamber by means of a gas flow.
• the filling level of the dosing chambers is subject to fluctuations. As a result, the flow of particles emitted by the dosing device over time, which is transported as an aerosol to an evaporator, fluctuates.
• the invention is based on the object of developing the above-mentioned method for generating a steam flow and the above-mentioned device in such a way that the steam flow can be kept within narrower tolerances at least during a steam generation phase.
• the invention is also based on the object of specifying a method with which an operating point can be set at which evaporation rates/vapor flows that are more stable over time are generated.
• the working point of a device of this type is defined at least by a working temperature, which is an evaporation temperature, i.e. a temperature of the evaporation surfaces of the evaporator, and by a working setting value, with the working setting value being referred to below as the working speed and the speed of a Dosing element is.
• the operating point is selected in such a way that the device according to the invention delivers a vapor flow or has an evaporation rate that corresponds to a desired value.
• This target value corresponds to a growth rate of a layer deposited on a substrate.
• the invention initially relates to a method for setting this operating point.
• a first evaporation temperature is defined in a first step.
• the first evaporation temperature lies in an area of a characteristic curve of the evaporator in which the evaporation rate is not dependent on the temperature, which runs horizontally across the temperature-deducted evaporation rate.
• the evaporation rate essentially only depends on the mass flow of the aerosol fed into the evaporator. In a speed range with a lower value that is below a speed at which the target value of the vapor flow is reached and with an upper value that is above the speed at which the target value is reached, several measurements are taken at constant temperature of the evaporation contact surfaces, but different speeds, i.e. setting values of the dosing device, a measurement curve is recorded.
• This temperature which is referred to below as the first evaporation temperature or first temperature, can be selected in such a way that the measurement curve is a straight line.
• the first evaporation temperature is consequently preferably selected in such a way that the vapor flow changes in a linear manner with the speed of the dosing element. However, it is sufficient if the ratio between the change in the evaporation rate and the change in the speed is almost constant.
• the lower value may be at least 10, 15, 20 or 25 percent below a value to which the vapor flow setpoint corresponds.
• the upper value can be at least 10, 15, 20 or 25 percent above this setting value, which corresponds to the setpoint.
• a working setting value ie a working speed
• a different first evaporation temperature is determined before the second step by varying the evaporation temperature and possibly also the speeds.
• the working speed is selected in such a way that the associated steam flow is lower than the steam pressure corresponding to the upper value of the speed range, but higher than the setpoint.
• the operating speed is preferably in a range between 10 and 20 percent above the speed at which the vapor flow would have the desired value at the first evaporation temperature. This speed can be determined by linear regression or other suitable methods.
• the working speed can then preferably correspond to 115 percent of the speed at which the steam flow would correspond to the desired value.
• the dosing device generates a mass flow of powder, which is transported as an aerosol flow to the evaporator, which is greater than the mass flow of vapor required to carry out a coating process, which should correspond to the setpoint.
• the evaporating temperature is gradually reduced until the vapor flow corresponds to the setpoint.
• the value determined for the evaporation temperature fur then forms the working temperature of the working point, which is further characterized by the working speed.
• the crossing point of the temperature curve with the curve of the characteristic curve moves from the horizontal area of the characteristic curve to an area of the characteristic curve that has a gradient.
• the coating process is carried out in an area of the characteristic that has a slope.
• This is preferably a transition area in which an area of the characteristic curve with an approximately constant slope transitions into a horizontally running area of the characteristic curve.
• a second vapor generation phase which follows the first vapor generation phase, the mass flow of the powder into the evaporator can be smaller than the mass flow of the vapor out of the evaporator.
• the enriched mass or part of the enriched mass can evaporate. Due to the fluctuating delivery rates of the aerosol, the two vapor generation phases can alternate several times in a row during a coating step. Overall, an unevaporated supply of material can build up over several coating processes. However, the excess mass flow to the evaporator is so low that during the vapor generation phase not so much organic matter is deposited on the evaporation surfaces that the evaporation rate is affected.
• the evaporation temperature can be kept constant for a long time, so that at the same temperature at which steam is generated in the steam generation phase, the mass accumulated on the evaporation surfaces can evaporate again in an optional regeneration phase following the evaporation phase.
• the device according to the invention has a regulating device or a control device or the like with which the aerosol flow can be specified and with which the evaporation temperature of the evaporator can be kept at a constant value.
• the control device is set up in such a way that it places the operating point in the range described above.
• the device according to the invention is operated according to the method according to the invention over a longer period of time at an operating point that is kept at a fixed value, which is selected in such a way that the first phase and the second phase are in the fluctuation range of the delivery capacity of the dosing element lies, so that when the operating point is kept at the fixed value, the device delivers a high flow rate in phases and a low flow rate in phases, and the evaporation temperature is selected in such a way that during the phase of the high flow rate, organic material accumulates in the Evaporator enriched and the mass of the enriched organic material decreases in the phase of a low flow rate.
• Fig. 1 shows schematically the course of a family of characteristics of an evaporator, which is supplied with a quantity of powder 7 to be evaporated, which is produced by a metering device 1, with H, Y2, 13, r ⁇ , 15 denote different mass flows of the powder to the vapor and the characteristic curve represents the vaporization rate V or the mass flow rate of the generated vapor over time for each mass flow rate of the powder,
• Fig. 2 schematically as a diagram of mass flow V over a first step and a second step of a method for determining a working point P, in which in the first step at a given temperature Ti of vaporizing surfaces 12 of a vaporizer 9 the mass flow of the Pulveis Kurs Veidampfei 9 increases wild and in the second slide by interpolation a work setting width i a ei means wild, in which a steam generation rate Va is about 15 percent larger than a set value Vs of the steam generation rate V,
• FIG 3 shows a schematic of the second and third step of the method, in a representation according to FIG a working temperature Ta is lowered until the steam generation rate at a working point P reaches the target value Vs,
• 4 shows a schematic of a device according to the invention in the form of a deposition device for OLEDs with a device for generating a vapor
• 5 shows a diagram of the course of steam generation, in which phase-wise different mass flows of the powder are conveyed into the evaporator, with more powder being conveyed into the evaporator in a first evaporation phase than vapor being conveyed out of the evaporator and in a second evaporation phase E 2 less powder is conveyed into the evaporator than vapor is conveyed out of the evaporator.
• a reactor 18 has a gas-tight housing and in the housing a gas inlet element 19 which is heated to a temperature which is greater than the condensation temperature of an organic material which is fed as vapor through a vapor discharge line 17 into the gas inlet element 19.
• the gas inlet element 19 has an essentially flat gas outlet surface with a large number of gas outlet openings arranged like a shower head.
• a substrate holder 21, which is cooled, is located below the gas outlet surface. On the substrate holder 21 is a substrate 20 that is to be coated with one or more OLED layers.
• a device for generating the vapor consists of a dosing device 1 with which a dosing element 5 is used to deliver a mass flow rate of a powder that is uniform within rough tolerances into a flow channel 4 .
• the dosing element 5 embodied as a toothed wheel or as a perforated disk can rotate in a powder store 7 in a storage container 6 .
• other suitable means such as screw conveyors, corrugated discs, perforated rollers or the like can also be used as metering element 5 .
• a mass flow controller 3 provides a carrier gas flow that flows through a carrier gas supply line 2 into the flow channel 4 and the powder 7 provided there is conveyed as an aerosol through an aerosol line 8 to an evaporator 9 .
• the aerosol line 8 opens into the evaporator 9 at an inlet opening 10.
• the evaporator 9 there are evaporation surfaces 12 that can be heated to evaporation temperatures T.
• the evaporation temperature is higher than the condensation temperature of the powder, so that the powder absorbs heat from the evaporation surfaces 12 in a gas form can be brought.
• the vapor generated in this way is conveyed by means of the flow of carrier gas through a vapor discharge line 17 to the gas inlet element 19 .
• An optional further mass flow controller 15 can provide a second carrier gas flow which is fed into the vapor discharge line 17 at a feed point 16 which is arranged between a sensor 13 and an outlet opening 11 of the evaporator 9 .
• the carrier gas provided by the mass flow controller 15 can also be fed into the evaporator 9 .
• the concentration of the vapor or the partial pressure of the vapor within the vapor discharge line 17 can be measured with the sensor 13 .
• a control device 14 is capable of using the setting value of the mass flow controller 3 to calculate the mass flow of the steam.
• the control device 14 is also able to influence the speed of the dosing element 5 in order to influence the conveying rate of the powder or the mass flow of the aerosol.
• the control device 14 is able to regulate the temperature of the evaporation surfaces 12, ie the evaporation temperature T, against a desired value.
• shut-off valves designated by the reference number 22 between the metering device 1 and the evaporator 9 or between the evaporator 9 and the reactor 18 are optional. They serve to save the organic starting material.
• the device shown in FIG. 4 is intended to provide a mass flow of vapor that corresponds to a setpoint value Vs. Which corresponds to a set value Vs and is constant within narrow limits over an evaporation time.
• the mass flow of the aerosol flowing from the dosing device 1 to the evaporator 9 through the aerosol line 8 depends on the speed r 1 to r 5 .
• the mass flow V of a vapor generated at a speed r 1 to r 5 through the vapor discharge line 17 is plotted against the vaporization temperature T as a characteristic curve.
• the vaporizer is loaded with more material than it can vaporize.
• the Dampff örderrate is dependent on the evaporation capacity of the evaporator 9 here.
• the amount of aerosol conveyed is largely irrelevant here.
• the characteristic curves which rise sharply in the lower temperature range, go into a transition range, in which the characteristic curves have a smaller slope or curvature, into a range in which the vapor flow V no longer depends on the evaporation temperature T, but only on depends on the speed r 1 to r 5 .
• the evaporation capacity of the evaporator 9 is sufficient here to evaporate all the material that is fed to the evaporator 9 via the aerosol line.
• the figure 2 shows a diagram in which the steam flow V is plotted against the speed R, a first step of a method for Determination of an operating point P at which steam flows V are measured at a first temperature Ti, which is shown in FIG. 3, at a plurality of speeds r 1 to r 5 in a speed range.
• the temperature Ti is selected in such a way that the steam flow V depends essentially linearly on the speed.
• the range of speeds is also selected such that a lower value r 1 is, for example, at least 25 percent below a speed rs that would correspond to a setpoint value Vs of the steam flow.
• An upper value r 5 is selected so that it is at least 25 percent above the speed r s .
• the evaporator 9 is operated with a constant evaporation temperature Ti.
• the vapor flow V is measured in several consecutive steps at different conveying rates of the powder.
• the distances between the delivery rates can be smaller in order to determine the delivery rate rs at which the desired value Vs of the steam flow is reached. It is essential here that measuring points are recorded above the setpoint value Vs.
• an interpolation for example a linear interpolation, to determine the value rs.
• a working speed r a is determined.
• the value r a is selected such that a vapor flow resulting from the measurement curve in FIG. 2 has a value Va which is approximately 15 percent greater than the setpoint value Vs. This occurs at the same constant first temperature Ti.
• FIG. 3 shows that the first temperature Ti lies in an area of the family of characteristics in which the characteristics run horizontally.
• the characteristic line which corresponds to the working speed r a , is shown in bold in FIG.
• the evaporation temperature T is changed and in particular reduced step by step or continuously or in the manner of an interval nesting until the vapor flow V achieved at the working speed ra has reached the desired value Vs .
• the temperature can initially be reduced in large steps and changed in smaller steps when the steam flow V approaches the setpoint value Vs.
• a deposition process is then carried out during a vapor generation phase E 1 , E 2 .
• the growth rate of the layer deposited on the substrate 20 is directly proportional to the vapor flow V. Since the desired value Vs of the vapor flow lies in an area of the characteristic curve in which the characteristic curve has a slope, ie does not run horizontally reduce the tolerance range in which the steam generation rate, ie the steam flow and thus also the growth rate, fluctuates.
• FIG. 5 shows, for example, a section of the time course of a method in which vapor is generated by feeding an aerosol into the evaporator 9 .
• Steam generation phases are denoted by Ei and E 2 .
• the vapor generation phase Ei shows a time segment during a deposition process in which the aerosol flow to the evaporator 9 is greater than the vapor flow emerging from the evaporator 9 .
• the shaded area shows the mass accumulation of the unevaporated material in the evaporator 9.
• the vapor generation phase E 2 shows a different time segment during the deposition process, in which the aerosol flow to the evaporator 9 is smaller than the vapor flow emerging from the evaporator 9 .
• the hatched area here shows a kind of negative mass accumulation, namely the disappearance of the mass accumulation generated in the first vapor generation phase E 1 . Due to the fluctuations in the delivery rates of the aerosol, a large number of these vapor generation phases alternate in the course of the coating process.
• a method which is characterized in that in a first step, a first evaporation temperature Ti and a setting value r 1 , r 2 , r 3 , r 4 , r 5 are determined, in which the vapor flow V by varying the A - Control value r changes from a lower value r 1 below a target value Vs of the steam flow V, in particular in a linear manner, by increasing the set value r to an upper value r 5 above the target value Vs.
• a method characterized in that in a second step a first work setting value r a is determined, at which the steam flow has a work value Va, which is smaller than the steam flow V at the upper value r5, but larger than that setpoint vs.
• a method which is characterized in that in a third step a working evaporation temperature Ta is determined at which the vapor flow V corresponds to the setpoint Vs.
• a method which is characterized in that the duration of the steam generation phase E 1 , E 2 in the range between 5 seconds.
• a device which is characterized in that the control device 14 is set up in such a way that it sets the working setting value r a and the evaporation temperature T to values at which the mass flow V of the vapor from the evaporator 9 is smaller , as the average mass flow of the powder 7 supplied to the evaporator 9 and an operating point P formed by the operating setting value r a and the evaporation temperature T is selected such that a characteristic curve representing the evaporation rate V versus the temperature at the operating point P has a slope.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)

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Citations (9)

• 2020
  • 2020-09-11 DE DE102020123764.2A patent/DE102020123764A1/de active Pending
• 2021
  • 2021-08-25 WO PCT/EP2021/073492 patent/WO2022053319A1/de active Application Filing
  • 2021-09-07 TW TW110133129A patent/TW202229587A/zh unknown

Patent Citations (9)

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