DE102011001642A1 - Preparing a polymer layer on a substrate, comprises providing the substrate, initiating the polymerization of a monomer with a free radical initiator and feeding a gaseous radical initiator to the substrate - Google Patents

Abstract

Preparing a polymer layer on a substrate, comprises providing the substrate, initiating the polymerization of a monomer with a free radical initiator and feeding a gaseous radical initiator to the substrate. The radical initiator is present as a part in a chemical compound, which is fed as a gaseous photolytic radical initiator and is released with electromagnetic radiation of a predetermined wavelength of the radical initiator of the chemical compound. An independent claim is also included for a device comprising a sealable reaction chamber, a feeding device for supplying a monomer, a supply line for supplying a gaseous initiator for initiating the polymerization, and a region of a substrate, and a window for coupling electromagnetic radiation of a predetermined wavelength into the reaction chamber for releasing the radical initiator as a part of the chemical compound in the form of a photolytic radical initiator.

Description

The invention relates to a method for producing a polymer layer on a substrate, in which the substrate is provided, in which a monomer, the polymerization of which can be introduced with a free-radical initiator, and a gaseous radical initiator are fed to the substrate. Furthermore, the invention relates to an apparatus for carrying out the method according to the invention with a closable reaction chamber, a feed for supplying a monomer, a feed for supplying a gaseous initiator for initiating a polymerization, and a region for a substrate.

Such a method and such a device are known from US 7,618,680 B2 known. Here, a large-area, homogeneous polymer layer is deposited by means of a chemical vapor phase epitaxy in a reaction chamber on a surface of a substrate. Specifically, EDOT (3,4-ethylenedioxythiophene) as a monomer in the gas phase is passed over the substrate simultaneously with bromine gas as an oxidizing substance. As a result, highly conductive polymer layers of the polymer PEDOT (poly (3,4-ethylenedioxythiophene)) can be deposited by means of the CVD technique (CVD: chemical vapor deposition).

The disadvantage is that for the production of electronic and / or optoelectronic components often the deposition of a sequence of different inorganic and / or organic polymers is necessary and additionally structuring of each individual layer by optical lithography or electron beam lithography method must be performed to the desired structure and to achieve functionality of the components. In the subsequent structuring there is a risk that already deposited, deposited polymer layers are damaged and / or destroyed in their integrity. Furthermore, the entire process for manufacturing the device can be very complicated and complex, which leads to high costs.

It is therefore the problem underlying the invention to provide a method and a device of the type mentioned above, with which the production of a polymer layer is improved and simplified.

The problem is solved by a method of the type mentioned in the introduction, wherein the radical initiator is contained as a part in a chemical compound which is supplied as a gaseous photolytic radical initiator, and with electromagnetic radiation of a predetermined wavelength of the radical initiator from the chemical compound is released.

It is advantageous that the radical initiator initiating the polymerization is not supplied as such and / or introduced into a reaction chamber, whereby the polymerization is not triggered directly over the entire substrate. Instead, a kind of precursor of the radical initiator, namely a chemical compound comprising the radical initiator as a part and / or as an element, is supplied in the form of a photolytic radical initiator in a gas phase and / or introduced into the reaction chamber. Only when in addition electromagnetic radiation, in particular light, is provided with a wavelength suitable for the photolysis, the chemical compound is cleaved and released the radical initiator. Only then is the polymerization started. This makes it possible to selectively control the polymerization and the formation of the polymer layer. Furthermore, this material can be saved in the production of electronic and / or optoelectronic components.

Preferably, the radical initiator is part of a gaseous chemical compound which is supplied as a photolytic precursor of the free-radical initiator, and is released with electromagnetic radiation of a predetermined wavelength of the radical initiator from its precursor. Thus, the free radical initiator is passed over the substrate as a precursor compound or precursor, and by means of the energy of the given wavelength, the free radical initiator is released from the precursor compound or its precursor. The free radical initiator may be a part and / or an element of the precursor and / or the precursor compound.

The entire manufacturing process for such a device can be significantly simplified. Thus, for example, a subsequent lithography can be omitted partially or completely. In addition, the method according to the invention can be combined with other methods for site-selective deposition, in particular in a production process. This allows the production of complex hybrid components without further manufacturing steps. In the case of hybrid components, for example, inorganic semiconductor elements, in particular in a vacuum and without contamination with other chemicals, are coated with at least one organic polymer layer. Thus, known semiconductor systems can be combined with functional polymers, as a result of which novel functionalities can be realized, such as, for example, chemical stability, dirt and water repellency or white light emission, etc. It is also possible to continue organic semiconductor elements, such as organic LEDs (OLEDs), easier to produce.

The electromagnetic radiation is provided for a certain period of time, which is necessary in particular for forming a specific layer thickness of the polymer layer. This period of time is usually several minutes.

According to a further embodiment, a region of the substrate provided for the polymer layer is irradiated with a beam of the electromagnetic radiation of the predetermined wavelength for the site-selective release of the radical initiator. Only where the beam, in particular the light beam, strikes the region of the substrate intended for the formation of the polymer layer or the surface of the substrate and / or a polymer layer already deposited on the substrate becomes the free-radical initiator released from the chemical compound. As a result, the polymerization and the formation of the polymer layer are controlled and localized. It is thus possible to deposit polymers only at the locations on a substrate and / or another pre-existing polymer layer where their functionality is needed. The monomer may be applied in solution to the substrate and then polymerized in situ with a suitable photolytic radical initiator by means of radiation of a suitable wavelength.

Preferably, the monomer is fed in the gas phase. By feeding a gaseous monomer, the process is simplified. Thus, for example, the gaseous monomer can be introduced into the reaction chamber simultaneously with the gaseous photolytic radical initiator, in particular as a gas mixture, and / or passed over the surface of the substrate. Preferably, the reaction chamber is formed as a vacuum chamber. As a result, impurities are avoided.

According to a development, the polymer layer is insulating or conductive. Only the location-selective deposition of insulating and electrically conductive polymers allows the production of electronic and / or optoelectronic components within a single device, in particular by means of fewer process steps. Preferably, the conductive polymer layer is doped by means of the radical initiator to increase the electrical conductivity. In particular, the polymerization takes place simultaneously due to the radical initiator and the doping by means of the radical initiator. As a result, a subsequent subsequent doping is avoided and the number of individual, in particular successive steps, reduced.

Preferably, the substrate and / or a reaction chamber are heated to evaporate unpolymerized monomers from the surface of the substrate to a predetermined evaporation temperature. As a result, an optionally disturbing the desired functionality contamination of the component to be produced is avoided. In addition, unused monomer can be made available for further use for the polymerization.

According to a further embodiment, unused gases are removed from the reaction chamber for the production of the polymer layer, in particular pumped out. As a result, the unused gases and their components can be made available for further utilization. In addition, the reaction chamber is emptied of gases after forming a first polymer layer, so that subsequently at least one other gas and / or gas mixture in the reaction chamber, in particular for forming a second polymer layer different from the first polymer layer, can be introduced.

The above-mentioned process steps can be carried out sequentially or simultaneously. With a simultaneous introduction of the, in particular gaseous, monomer, the gaseous photolytic radical initiator, the irradiation with light, the doping, the evaporation and / or the discharge of unused gases, the time for producing a polymer layer and / or a complex component can be significantly reduced. Preferably, the aforementioned steps for producing any desired layer thicknesses and / or for producing electronic and / or optoelectronic components with a suitable monomer and a suitable photolytic radical initiator are repeated.

According to a further development, the monomer used is 3,4-ethylenedioxythiophene (EDOT), 3-hexylthiophene (3HT), styrene or methyl methacrylate (MMA). Thus, it is possible to use monomers which, depending on the desired functionality, are suitable for the production of electrically conductive polymer, for example 3,4-ethylenedioxythiophene (EDOT) or 3-hexylthiophene (3HT) as monomer or insulating polymer, for example in the case of styrene or methyl methacrylate (MMA) Monomer, are suitable.

Further, as a photolytic radical initiator dibutyl peroxide or a halogen-containing compounds, in particular chlorofluorocarbons (CFC), chloroform, n-bromosuccinimide, bromobutane, carbon tetrabromide or dichloromethane can be used. Especially for EDOT is one Doping which is achievable by means of a halogen desirable. The doping can take place subsequently, preferably the doping takes place in-situ and / or simultaneously with the polymerization. In this case, the initiators used to initiate the polymerization are halogen-containing photolytic radical initiators, in particular certain chlorofluorocarbons (CFCs), chloroform, n-bromosuccinimide, bromobutane, carbon tetrabromide, dichloromethane or other short-chain halogenated hydrocarbons.

Preferably, the predetermined wavelength is in the ultraviolet (UV) spectrum. Thus, the wavelength is in a range between 1 nm and 380 nm. This wavelength range is suitable, in particular for halogen-containing compounds, usually for the photolysis or decomposition of the photolytic radical initiator. The UV light can be provided by means of a UV laser, in particular a HeCd laser with a wavelength of 325 nm. By means of a laser, certain structures of the polymer layer can be produced particularly precisely. Thus, for example, halogen atoms are selectively releasable, whereby the polymerization process and / or the doping of the resulting, in particular conductive, polymer are controllable. In the case of unstable organic photolytic radical initiators, light, in particular a laser, having a wavelength in the visible spectrum can be used.

According to a further development, in particular in the reaction chamber, a pressure in the range from normal pressure to about 1 mbar is set. The deposition rate of the polymer is dependent on the pressure. Thus, a pressure suitable for a sufficient deposition rate, in particular in a reaction chamber, is set. At a pressure of 1 mbar, a typical deposition rate of less than 50 nm / h results.

Preferably, 10 ml / min to 100 ml / min, in particular 10 ml / min, are supplied from the gaseous monomer. From the gaseous photolytic radical initiator about 100 ml / min can be supplied. These are typical orders of magnitude of the material flow which have proven to be advantageous.

The device according to the invention for carrying out the method according to the invention has a window for coupling an electromagnetic radiation of a predetermined wavelength into the reaction chamber for releasing a radical initiator as a part of a chemical compound in the form of a photolytic radical initiator. By means of the window, for example by means of a laser arranged outside the reaction chamber, radiation of a suitable wavelength can be introduced or coupled into the reaction chamber. As a result, the polymerization can be triggered in a location-selective manner. The light source is accessible at all times. This is advantageous in particular for the alignment and / or positioning of the beam, for example to write a specific structure.

The feeds may be formed as a connection. The port for introducing the, in particular gaseous, monomer and the port for introducing the gaseous photolytic radical initiator into the reaction chamber may be formed as a single common port or two separate ports. Furthermore, the device can have a discharge and / or a further connection for discharging unused gases.

The invention will be explained in more detail with reference to the following figures. Show it:

1 a flow chart for a method according to the invention,

2a - 2c a schematic representation of a second method according to the invention,

3a - 3g a schematic representation of another method according to the invention, and

4 a schematic representation of an apparatus for performing a method according to the invention.

1 shows a flow chart for a method according to the invention. In a step S10, the process for producing a polymer layer on a substrate is started. In a step S11, the substrate is arranged, for example, in a closable reaction chamber. The substrate may have a planar or porous surface. As a material for the substrate, for example, glass or silicon can be used.

In a step S12, a gaseous monomer is supplied or introduced into the reaction chamber. In this case, a gaseous monomer is used whose polymerization can be initiated by a radical initiator. In a step S13, a gaseous photolytic radical initiator is fed or introduced into the reaction chamber. This photolytic radical initiator is a chemical compound containing the radical initiator as a part necessary for the polymerization. Thus, the polymerization is initially not initiated by the introduction of the gaseous monomer and the gaseous photolytic radical initiator.

In a step S14, a substrate region is irradiated with electromagnetic radiation of a predetermined wavelength for releasing the radical initiator from the chemical compound. The wavelength is chosen as a function of the photolytic radical initiator such that the incident radiation applies sufficient energy to cleave the bond of the photolytic radical initiator so that the free radical initiator is released. As a result, in the areas in which the substrate is irradiated with the radiation, the polymerization is triggered. As a result, a polymer layer is formed in the areas irradiated by the radiation on the substrate.

The method according to the invention is then terminated in a step S18. Alternatively, however, further steps S15, S16 and S17 may be provided.

In a step S15, the polymer layer is doped to achieve a better electrical conductivity in a conductive polymer. In a step S16, unpolymerized monomers are evaporated from the substrate. The evaporation takes place by heating or heating the reaction chamber and / or the substrate. Finally, unused gases are removed from the reaction chamber in a step S17.

The steps S12 to S14 or the steps S12 to S17 may be performed sequentially or at least partially simultaneously. Further, steps S12 to S14 or steps S12 to S17 may form one cycle. This cycle can be carried out repeatedly to form an arbitrary layer thickness and / or an electronic and / or optoelectronic component.

2a - 2c show a schematic representation of a second method according to the invention.

2a is a substrate 10 can be seen that is arranged in a reaction chamber, not shown here. Into the reaction chamber and the space above the surface of the substrate 10 is according to arrow 11 a gas mixture 12 initiated. The gas mixture 12 consists of gaseous monomer whose polymerization with a radical initiator can be introduced. Next contains the gas mixture 12 a gaseous photolytic radical initiator. In the embodiment shown here, the material flow of the monomer is about 10 ml / min and the photolytic radical initiator about 100 ml / min.

2 B shows the substrate 10 with the gas mixture 12 according to 2a , The surface of the substrate 10 is with a ray of light 13 irradiated a predetermined wavelength. In the embodiment shown here, the light beam 13 a wavelength of 325 nm and is thus located in the UV range. Next is the light beam 13 generated with a laser not shown here. By means of the laser becomes a certain area of the surface of the substrate 10 irradiated. This is a UV laser, namely a HeCd laser. The light beam 13 is by means of a positioning device not shown here in detail, as with the double arrow 14 indicated, positioned according to the desired structure of the polymer layer.

2c is the substrate 10 according to 2a and 2 B after the completion of the irradiation with the light beam 13 refer to. In the area of the surface of the substrate 10 by the light beam 13 has been irradiated, has become a polymer layer 15 educated. The gas mixture 12 is by means of a pumping device not shown here from the reaction chamber, as with arrow 16 indicated, pumped out.

3a - 3g show a schematic representation of another method according to the invention, in which by a method according to 1 and 2a - 2c an LED is made. Same items as at 2a - 2c bear the same reference numbers. In that regard, reference is also made to the preceding description.

3a is a substrate 10 whose surface is covered with a layer of zinc oxide (ZnO) nanowires 17 is covered. A gas mixture 18 becomes, as with the arrow 11 indicated, introduced into the reaction chamber. The gas mixture 18 contains gaseous styrene as a monomer and a gaseous halogen-containing compound, namely chloroform, as a photolytic radical initiator, wherein the two gases are simultaneously conducted into the reaction chamber.

To 3b becomes the surface of the substrate 10 or the layer of ZnO nanowires 17 with a ray of light 13 irradiated a predetermined wavelength. The light beam 13 is generated by a laser not shown here. The light beam 13 is by means of a positioning device, also not shown in detail, as with the double arrow 14 indicated, positioned according to the desired structure of the polymer layer to be produced. The wavelength of the light beam 13 is selected so that the radical initiator chlorine is released from the chemical compound of the photolytic radical initiator. As a result, the polymerization is set in motion.

According to 3c Has become in the area of the surface of the substrate 10 or the ZnO nanowires 17 that from the light beam 13 irradiated were, a polymer layer 19 made of polystyrene. The gas mixture 18 is by means of a pumping device not shown here from the reaction chamber, as with arrow 16 indicated, pumped out.

Subsequently, the reaction chamber after 3d with a gas mixture 20 filled. The gas mixture 20 is composed of gaseous EDOT as monomer and gaseous chloroform as photolytic radical initiator. Both gases are simultaneously fed into the reaction chamber.

To 3e becomes the surface of the polymer layer 19 that is here as a substrate 19 serves for a further polymer layer, with a light beam 13 irradiated a predetermined wavelength. The light beam 13 is generated again with a laser not shown here. Next is the light beam 13 by means of the positioning device, as with the double arrow 14 indicated, according to the desired structure of the polymer layer to be generated shifted. The wavelength of the light beam 13 is again chosen to start the polymerization so that the radical initiator chlorine is released from the photolytic radical initiator.

3f is the substrate 10 and the polymer layer 19 after completion of the irradiation with the light beam 13 refer to. In the area of the surface of the polymer layer 19 by the light beam 13 has been irradiated, has become another polymer layer 21 formed from PEDOT. The gas mixture 20 is removed by means of the pumping device from the reaction chamber, as with arrow 16 indicated, pumped out.

This results in a structure corresponding to a ZnO / polystyrene / PEDOT LED and according to 3g an electrical contact 22 is assignable.

The temperature of the substrate 10 or the polymer layer 19 influences the mobility of the monomers from the gas mixture 18 . 20 on the substrate 10 or the polymer layer 19 , This will at the same time the quality of the resulting polymer layer 19 affected. For styrene, a temperature of less than 30 ° C has proven to be particularly advantageous. Otherwise, the monomer styrene gets too light from the substrate 10 desorbed and no polymerization is initiated. In the steps according to 3a to 3c Thus, a substrate temperature of less than 30 ° C is provided.

For (P) EDOT, the conductivity increases with the temperature for the substrate 10 , Particularly advantageous is a temperature of about 100 ° C has been found. This temperature of the substrate 10 is in the steps according to 3d to 3f intended.

4 shows a schematic representation of a device 23 for carrying out a method according to the invention. The device 23 includes a reaction chamber 24 in which a substrate 10 is arranged. In the embodiment shown here, the reaction chamber 24 as a vacuum chamber 24 educated. Next are a first feeder 25 in the training of a first connection 25 for introducing a gaseous monomer and a second feed 26 in the training of a second connection 26 for introducing a gaseous photolytic radical initiator into the reaction chamber 24 intended. In an alternative embodiment, the first port 25 and the second connection 26 also be summarized in a common connection.

Another feeder 27 in the form of another connection 27 is for removing unused gases from the reaction chamber 24 intended. In the embodiment shown here is the connection 27 at one of the terminals 25 . 26 remote side of the reaction chamber 24 positioned.

At one of the substrate 10 remote side of the reaction chamber 24 or the substrate 10 opposite is a window 28 in a wall of the reaction chamber 24 admitted. By means of the window 28 is a ray 13 one outside the reaction chamber 24 arranged laser 29 in the reaction chamber 24 be coupled. This is where the beam hits 13 on the surface of the substrate 10 ,

The invention will be described below with reference to FIG 1 to 4 explained in more detail:
By means of the methods described above and the device designed for this purpose 23 is a site-selective deposition of polymers from the gas phase feasible. The polymer layers 15 . 19 . 21 will only be at the places on the substrate 10 and / or the polymer layer 19 separated, where this is needed for the intended functionality.

The site-selective deposition is achieved in which the radical initiator which initiates the polymerization in a precursor as a gaseous photolytic radical initiator in the reaction chamber 24 is initiated. Only there, where a ray 13 an electromagnetic radiation having a wavelength suitable for the photolysis on the surface of the substrate 10 and / or the polymer layer 19 meets, the radical initiator is released. Thus, the polymerization takes place in a controlled and localized manner.

As a result, material is saved in the production and other complex processing steps, such as lithography avoided. The production of hybrid components, organic semiconductor elements, complex three-dimensional structures by targeted deposition of layer sequences such as field effect transistors and / or light-emitting structures is significantly simplified.

LIST OF REFERENCE NUMBERS

S10

begin

S11

Arrange substrate

S12

introduce gaseous monomer

S13

initiate gaseous photolytic radical initiator

S14

Irradiate substrate area with light

S15

endowment

S16

evaporation

S17

Removal of unused gases

S18

The End

10

substratum

11

arrow

12

mixture of gases

13

beam

14

double arrow

15

polymer layer

16

arrow

17

ZnO nanowires

18

mixture of gases

19

polymer layer

20

mixture of gases

21

polymer layer

22

Electric contact

23

contraption

24

reaction chamber

25

feed

26

feed

27

removal

28

window

29

laser

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• US 7618680 B2 [0002]

Claims (10)

Method for producing a polymer layer ( 15 . 19 . 21 ) on a substrate ( 10 ), in which the substrate ( 10 ), in which a monomer whose polymerization with a free-radical initiator can be introduced, and a gaseous radical initiator are added to the substrate ( 10 ), characterized in that the radical initiator is contained as a part in a chemical compound supplied as a gaseous photolytic radical initiator, and with electromagnetic radiation of a predetermined wavelength the radical initiator is released from the chemical compound. Method according to claim 1, characterized in that one for the polymer layer ( 15 . 19 . 21 ) provided area of the substrate ( 24 ) with a beam ( 13 ) is irradiated to the electromagnetic radiation of the predetermined wavelength for the site-selective release of the radical initiator, wherein preferably the monomer is supplied in the gas phase. Method according to claim 1 or 2, characterized in that the polymer layer ( 15 . 19 . 21 ) is insulating or conductive, wherein preferably the conductive polymer layer ( 15 . 19 . 21 ) is doped by means of the radical initiator to increase the electrical conductivity. Method according to one of the preceding claims, characterized in that the substrate ( 10 ) and / or a reaction chamber ( 24 ) for evaporating unpolymerized monomers from the surface of the substrate ( 10 ) are heated to a predetermined evaporation temperature. Method according to one of the preceding claims, characterized in that for the production of the polymer layer ( 15 . 19 . 21 ) unused gases from a reaction chamber ( 24 ) are discharged, in particular pumped out, be. Method according to one of the preceding claims, characterized in that 3,4-ethylenedioxythiophene (EDOT), 3-hexylthiophene (3HT), styrene or methyl methacrylate (MMA) is used as the monomer. Method according to one of the preceding claims, characterized in that dibutyl peroxide or halogen-containing compounds, in particular chlorofluorocarbons (CFC), chloroform, n-bromosuccinimide, bromobutane, carbon tetrabromide or dichloromethane, is used as the photolytic radical initiator. Method according to one of the preceding claims, characterized in that the predetermined wavelength is in the ultraviolet (UV) spectrum, wherein preferably the UV light by means of a UV laser, in particular a HeCd laser with a wavelength at 325 nm, is provided. Method according to one of the preceding claims, characterized in that, in particular in the reaction chamber ( 24 ), a pressure ranging from normal pressure to about 1 mbar is set, and / or that from the gaseous monomer 10 ml / min to 100 ml / min, in particular 10 ml / min, and the gaseous photolytic radical initiator about 100 ml / min are supplied , Device for carrying out the method according to one of the preceding claims with a closable reaction chamber ( 24 ), a feeder ( 25 ) for feeding a monomer, a feed ( 26 ) for supplying a gaseous initiator for initiating the polymerization, and a region for a substrate ( 10 ), characterized by a window ( 28 ) for coupling an electromagnetic radiation of a predetermined wavelength into the reaction chamber ( 24 ) for releasing a radical initiator as a part of a chemical compound in the form of a photolytic radical initiator.

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