DE102020122800A1 - Device for depositing OLED layers with a run/vent line - Google Patents

Abstract

The invention relates to a device and a method for depositing a layer on a substrate (9) or for providing a vapor for depositing such a layer, with an evaporator (1) for evaporating a non-gaseous starting material provided by a metering device (2), a vapor line (3) which fluidly connects the evaporator (1) to a changeover valve arrangement (4), by means of which the vapor transported through the vapor line (3) with a carrier gas can be routed either into a process chamber (6) of a coating reactor (7) or past it and with a sensor (5) arranged in the steam line (3) for determining the concentration or the partial pressure of the steam transported through the steam line (3). In order to avoid false signals being generated when switching over from a QCM sensor used as a sensor, there is a pressure barrier between the sensor (5) and the switching valve arrangement (4), which is preferably formed from graphite foam.

Description

field of technology

The invention relates to a device for depositing a layer on a substrate or for providing a vapor for depositing such a layer, with an evaporator for evaporating a non-gaseous starting material provided by a dosing device, a vapor line, which fluidly connects the evaporator with a switching valve arrangement, by means in which the vapor transported with a carrier gas through the vapor line can be routed either into a process chamber of a coating reactor or past it, with a sensor arranged in the vapor line for determining the concentration or the partial pressure of the vapor transported through the vapor line.

The invention also relates to a method for depositing a layer on a substrate, in which an evaporator is used to vaporize a non-gaseous starting material provided with a metering device, the vapor thus generated is passed together with a carrier gas through a vapor line to a switching valve arrangement and from there is conducted either into a process chamber of a coating reactor or past it, with the concentration or the partial pressure of the vapor transported through the vapor line being determined using a sensor arranged in the vapor line.

State of the art

Devices for depositing OLED layers are known in the prior art. A device including an evaporator for evaporating an organic, non-gaseous starting material is shown in DE 10 2014 102 484 A1 . A sensor with which the vapor pressure or the concentration of a vapor in a vapor line can be measured is described, for example, in DE 10 2017106 968 A1 . A gas supply system for providing a vapor for an OLED coating device is in the DE 10 2020 103 822 A1 described.

The state of the art also includes the US 10,256,126 B2 and US 9,856,563 B2 .

In a device for depositing an OLED layer or in a method for depositing an OLED layer, a non-gaseous starting material is provided with a metering device. The dosing device is set up in such a way that it supplies a mass flow of a powder or a liquid which is essentially uniform over time. The powder or liquid is transported as an aerosol by a carrier gas from the dosing device to the vaporizer. Due to different particle sizes of the powder or other, in particular mechanical, inadequacies of a dosing device, the temporal mass flow of the powder is subject to fluctuations. These fluctuations can be compensated, inter alia, by a variation in the carrier gas mass flow and/or a variation in the evaporation temperature of evaporation surfaces within the evaporator. The mass flow leaving the evaporator is measured with a QCM sensor. The sensor signal of the QCM sensor is not only sensitive to the partial pressure or the concentration of the vapor in the vapor line, but also to the total pressure within the vapor line.

In a device according to the invention, a switching valve arrangement is provided with which the mass flow of vapor provided by the evaporator can be introduced either directly into a gas inlet element of a coating reactor through a run line or can be routed past the coating reactor through a vent line. With such an arrangement, the mass flow of the vapor can stabilize at a desired value before the actual coating process begins. After the mass flow of the vapor has stabilized, the switching valve arrangement is switched over in such a way that the vapor no longer flows through the vent line but through the run line into the gas inlet element. When switching over, there are brief fluctuations in the total pressure. These fluctuations can be recognized as waves in a diagram of the total pressure recorded over time and disrupt the control behavior of the control device, with which the mass flow of the vapor is kept constant.

Summary of the Invention

The invention is based on the object of specifying measures with which the disadvantages described above are eliminated. The invention is based in particular on the object of specifying measures with which a uniform mass flow of the steam can be ensured at the time of switching even when using a switching valve arrangement.

The problem is solved by the technical teaching specified in the claims, the subclaims not only representing advantageous developments of the invention specified in the independent claims, but also independent solutions to the problem.

First and foremost, a pressure barrier disposed between the sensor and the switching valve assembly is provided. The pressure barrier is designed in such a way that when the carrier gas and the vapor transported by the carrier gas flow through the pressure barrier, a slightly higher pressure is set upstream of the pressure barrier than downstream of the pressure barrier. With a total pressure of 150 Pa, the pressure drop across the pressure barrier can be greater than 5 Pa, so that pressure peaks up to 5 Pa can be sufficiently smoothed out. In a preferred embodiment of the invention, the pressure barrier is formed by an open-cell foam body. It is a solid-foam body and in particular a graphite foam body. The pressure barrier preferably fills the entire free cross section of the vapor line. The steam line can be a DN 40 pipe. The switching valve arrangement has at least two valves. Depending on the valve position, a first valve connects or disconnects the vapor line to/from a run line through which the carrier gas transports the vapor to a gas inlet element of the coating reactor. The switching valve arrangement also has a second valve which, depending on the valve position, connects or disconnects the vapor line to a vent line, with the vent line transporting the vapor transported by the carrier gas past the coating reactor. A discharge line can be provided, into which the vent line and a gas discharge line of the coating reactor open. It is also provided that the pressure barrier can be heated by a heating device. The heating device can be a heating sleeve. However, it can also be provided that the pressure barrier, in particular if it is formed from an open-cell graphite foam, is heated by passing an electric current through it. In this case, the heating device is formed by electrodes with which a current can be conducted through the pressure barrier. The pressure barrier can preferably be heated to temperatures in the range between 20 and 450° C. with the heating device. A control device can be provided, with which the temperature of the pressure barrier is controlled to a target temperature. This control device can be integrated into a control device for controlling the mass flow of the steam. A temperature of an evaporation surface within the evaporator can be varied with the regulating device for regulating the mass flow of the vapor. The control device can also be able to vary the mass flow of the carrier gas through the metering device. These two manipulated variables are varied in the manner known from the prior art in order to achieve a constant mass flow of the steam through the steam line. For this purpose, the partial pressure or the concentration of the vapor in the vapor line is determined using a sensor, in particular a QCM sensor. Optionally, a pressure sensor can be provided with which the gas pressure within the vapor line can be determined.

The pressure inside the evaporator can range from 1 to 80 mbar. However, the pressure range is preferably in a range between 2 and 40 mbar. The pressure within the evaporator is particularly preferably not more than 10 mbar. A typical pressure is in the range between 3 and 4 mbar. A pressure in the range between 0.1 and 10 mbar can drop above the preferably heated pressure barrier. The pressure drop is preferably in the range between 1 and 5 mbar or 1 and 3 mbar. A typical pressure is in the range between 1 and 2.5 mbar. Two measuring probes are provided, each of which is preferably arranged in a dead volume upstream of the pressure barrier. It is a QCM sensor and pressure gauge.

character list

• 1 schematisch die Elemente einer Vorrichtung eines ersten Ausführungsbeispiels zum Abscheiden einer Schicht auf einem Substrat,
• 2 den Schnitt gemäß der Linie II-II durch eine Druckbarriere 8,
• 3 schematisch den zeitlichen Verlauf eines von einem Sensor 5 ermittelten Messwertes eines Massenflusses Q eines Dampfes durch die Dampfleitung 3, wenn als Folge eines Umschaltens der Umschaltventilanordnung 4 sich der Totaldruck Ptot kurzfristig ändert,
• 4 ein zweites Ausführungsbeispiel in einer Darstellung gemäß 1.

Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. Show it:

• 1 schematically the elements of a device of a first embodiment for depositing a layer on a substrate,
• 2 the section according to the line II-II through a pressure barrier 8,
• 3 schematically shows the course over time of a measured value of a mass flow Q of a vapor through the vapor line 3 determined by a sensor 5 if the total pressure Ptot changes for a short time as a result of a switchover of the switchover valve arrangement 4,
• 4 a second exemplary embodiment in a representation according to FIG 1 .

Description of the embodiments

A coating reactor 7 has a pressure-tight housing in which a gas inlet element 16 is located. Similar to a shower head, the gas inlet element 16 can have a multiplicity of gas outlet openings which are arranged on a gas outlet surface and open into a process chamber 6 whose floor is formed by a susceptor 18 . A substrate 9 to be coated can be placed on the susceptor 18 . While the gas inlet element 16 to an elevated temperature, which is above the condensation temperature of a vapor with the in the 1 device shown is fed into the gas inlet member 16, the susceptor 18 is at a temperature below the condensation temperature of the vapor, so that the vapor can condense on the surface of the substrate 9.

To generate the vapor, a mass flow controller 10 generates a mass flow of a carrier gas, for example an inert gas or nitrogen, which is fed into a metering device 2 through a carrier gas feed line 11 . The dosing device 2 contains means known in principle from the prior art in order to generate a flow of powder into the carrier gas flow that is as constant as possible over time. An aerosol generated in this way is transported to an evaporator 1 . The mass flow of the aerosol is subject to temporal fluctuations due to the non-uniform particle size of the powder and other mechanical imperfections.

Evaporation surfaces (not shown) are located in the evaporator 1 and add evaporation heat to the aerosol, with which the aerosol particles can be evaporated. The temperature of the evaporation surfaces can be varied by means of a control device 9, with which the mass flow of the carrier gas flowing through the mass flow controller 10 is also controlled. The above-mentioned fluctuations in the aerosol flow over time can be compensated for with these two control parameters.

The vapor generated in the evaporator 1 is transported through a vapor line 3 to a switching valve assembly 4 . The partial pressure of the vapor or the concentration of the vapor within the vapor line 3 is determined using a QCM sensor 5 in the manner known from the prior art. In addition, the total gas pressure within the steam line 3 can be determined with a pressure gauge 12 .

The switching valve arrangement 4 is able to selectively feed the gas flow emerging from the vapor line 3 either into a run line 15 or into a vent line 17 . For this purpose, the switching valve arrangement 4 has at least a first valve 13 and a second valve 14. If the first valve 13 is open and the second valve 14 is closed, the vapor transported by the carrier gas is fed into the run line, which opens into the gas inlet element 16. If, on the other hand, the first valve 13 is closed and the second valve 14 is opened, the vapor transported by the carrier gas is routed into the vent line 17 past the coating reactor 7 . The gas flow emerging from the coating reactor 7 leads into a discharge line 20 into which the vent line 17 can also lead.

When the valves 13, 14 of the switching valve arrangement 4 are switched over, pressure peaks can form which can briefly lead to an increase in the total pressure within the steam line 3. The pressure fluctuations when switching over can be seen as waves in a pressure-time diagram. The duration of such a wave is 0.5 to 2 seconds. The amplitude of such a wave is about 5 Pa. the 3 shows the time course of the total pressure Ptot when the valves 13, 14 are switched over at the times t1 and t2. Q is the measured value of the QCM sensor 5, which reports an increased concentration or an increased partial pressure at times T1, T2, which does not correspond to reality.

According to the invention, a pressure barrier 8 is located between the QCM sensor 5 and the switching valve arrangement 4 within the vapor line 3 . In the exemplary embodiments, the pressure barrier 8 is arranged directly in front of the switching valve arrangement 4 . In the exemplary embodiments, the pressure barrier 8 is formed by an open-pore graphite foam which can be heated with a heating device 19 . The heating device 19 can be a heating sleeve or electrodes with which a current can be conducted through the graphite foam. The foam can be 100 ppi foam. The foam body can have a thickness of 30 to 5 mm, preferably 40 mm, measured in the direction of flow. The pressure barrier 8 can be heated to temperatures of up to 450° C. with the heating device 19 .

The two in the 1 and 4 The exemplary embodiments shown differ essentially in the type of evaporation surfaces of the evaporator or in an intermediate store 21 in which a quantified quantity of the powder produced by the metering device 2 can be temporarily stored. The quantities quantified are brought into the evaporator 1 through a feed line 22 .

With the development of the prior art according to the invention, a representation according to FIG 3 the measured value Q supplied by the sensor 5. The in the 3 illustrated peaks at times t1 and t2 disappear. For this it is sufficient if the pressure difference at the pressure barrier 8 is approximately the value ΔP ( 3 ) that indicates the value of the pressure peak.

The above statements serve to explain the inventions covered by the application as a whole, which are state of the art at least through the following combinations of features can also develop their skills independently, whereby two, several or all of these feature combinations can also be combined, namely:

A device which is characterized by a pressure barrier 8 arranged between the sensor 5 and the switching valve arrangement 4.

A method characterized in that the vapor and the carrier gas are transported through a pressure barrier 8 arranged between the sensor 5 and the switching valve arrangement 4.

A device or a method characterized in that the pressure barrier 8 is an open-cell foam body that fills the cross-section of the vapor line 3 .

A device or a method, characterized in that the pressure barrier 8 consists of carbon or graphite.

A device or a method which is characterized in that the pressure barrier 8 is designed in such a way that pressure peaks of up to 5 Pa that occur when switching over the switching valve arrangement 4 are smoothed out at a total pressure of 150 Pa.

A device or a method characterized in that the switching valve arrangement 4 has a first valve 13 which, when open, connects the steam line 3 to a run line 15 to a gas inlet element 16 of the coating reactor 7 and that the switching valve arrangement 4 has a second valve 14 which, in the open state, connects the vapor line 3 to a vent line 17 .

A device or a method characterized by a control device 9, with which a temperature of evaporation surfaces of the evaporator 1 and the mass flow of the carrier gas through a mass flow controller 10 are dependent on a first measured value measured with the sensor 5 and a measured value with a pressure gauge 12 in the The second measured value measured in the steam line 3 can be varied in such a way that a time-constant mass flow of the steam passes through the pressure barrier 8 .

A device or a method characterized in that the sensor 5 is a QCM sensor, the starting material is an organic starting material and an OLED layer is deposited in the coating reactor 7 on a substrate 9 lying on a susceptor 18 .

A device or a method which is characterized in that the pressure barrier 8 is assigned a heating device with which the pressure barrier 8 can be heated to an elevated temperature.

All disclosed features are essential to the invention (by themselves, but also in combination with one another). The disclosure of the application also includes the disclosure content of the associated/attached priority documents (copy of the previous application) in full, also for the purpose of including features of these documents in claims of the present application. The subclaims, even without the features of a referenced claim, characterize with their features independent inventive developments of the prior art, in particular for making divisional applications on the basis of these claims. The invention specified in each claim can additionally have one or more of the features specified in the above description, in particular with reference numbers and/or specified in the list of reference numbers. The invention also relates to configurations in which individual features mentioned in the above description are not implemented, in particular if they are clearly superfluous for the respective intended use or can be replaced by other technically equivalent means.

Reference List

1

Evaporator

2

dosing device

3

steam line

4

switching valve assembly

5

QCM sensor

6

process chamber

7

coating reactor

8th

Pressure barrier/foam body

9

control device

10

mass flow controller

11

carrier gas supply line

12

pressure gauge

13

first valve

14

second valve

15

run line

16

gas inlet element

17

vent line

18

susceptor

19

heating device

20

derivation

21

cache

22

feed line

D

diameter

P

print

Q

mass flow

t1

Time

t2

Time

ΔP

value

Ptot

value

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102014102484 A1 [0003]
• DE 102017106968 A1 [0003]
• DE 102020103822 A1 [0003]
• US10256126B2 [0004]
• US 9856563 B2 [0004]

Claims (10)

Device for depositing a layer on a substrate (9) or for providing a vapor for depositing such a layer, with an evaporator (1) for evaporating a non-gaseous starting material provided by a metering device (2), a vapor line (3) which fluidly connects the evaporator (1) to a switching valve arrangement (4), by means of which the vapor transported with a carrier gas through the vapor line (3) can be routed either into a process chamber (6) of a coating reactor (7) or past it, and with a Sensor (5) arranged in the steam line (3) for determining the concentration or the partial pressure of the steam transported through the steam line (3), characterized by a pressure barrier (8) arranged between the sensor (5) and the switching valve arrangement (4). Process for depositing a layer on a substrate (9), in which a non-gaseous starting material provided with a metering device (2) is evaporated with an evaporator (1), the vapor thus generated together with a carrier gas through a vapor line (3) to a switchover valve arrangement (4) and from there either into a process chamber (6) of a coating reactor (7) or passed thereby, with a sensor (5) arranged in the vapor line (3) measuring the concentration or the partial pressure of the gas flowing through the vapor line (3 ) transported vapor is determined, characterized in that the vapor and the carrier gas are transported through a pressure barrier (8) arranged between the sensor (5) and the switching valve arrangement (4). device after claim 1 or procedures claim 2 , characterized in that the pressure barrier (8) is an open-cell foam body which fills the cross section of the steam line (3). Device or method according to one of the preceding claims, characterized in that the pressure barrier (8) consists of carbon or graphite. Device or method according to one of the preceding claims, characterized in that the pressure barrier (8) is designed in such a way that pressure peaks of up to 5 Pa which occur when switching over the switching valve arrangement (4) are smoothed out at a total pressure of 150 Pa. Device or method according to one of the preceding claims, characterized in that the switching valve arrangement (4) has a first valve (13) which, in the open state, connects the steam line (3) with a run line (15) to a gas inlet element (16) of the Coating reactor (7) connects and that the switching valve assembly (4) has a second valve (14) which connects the vapor line (3) with a vent line (17) in the open state. Device or method according to one of the preceding claims, characterized by a control device (9) with which a temperature of evaporation surfaces of the evaporator (1) and the mass flow of the carrier gas through a mass flow controller (10) are dependent on a first measured with the sensor (5). Measured value and a second measured value measured with a pressure gauge (12) in the steam line (3) are varied in such a way that a temporally constant mass flow of the steam passes through the pressure barrier (8). Device or method according to one of the preceding claims, characterized in that the sensor (5) is a QCM sensor, the starting material is an organic starting material and in the coating reactor (7) on a susceptor (18) lying substrate (9) an OLED layer is deposited. Device or method according to one of the preceding claims, characterized in that the pressure barrier (8) is assigned a heating device with which the pressure barrier (8) can be heated to an increased temperature. Device or method, characterized by one or more of the characterizing features of one of the preceding claims.

Images