KR20050016515A - Method for forming organic thin film - Google Patents

Abstract

An object of the present invention is to provide a method for forming an organic thin film which is capable of forming an organic thin film having a uniform film quality in a film surface without generating heat. The gas (film-forming component gas) g2 which vaporized the single film-forming component which consists of organic materials is produced | generated, and the film-forming component gas g2 is transported and supplied to the process chamber 11 in which the board | substrate W was accommodated. And the organic material which hold | maintained the film-forming component on the surface of the board | substrate W in the process chamber 11 is deposited, and an organic thin film is formed. When depositing an organic material, the substrate W is cooled. The film-forming component gas g2 is transported and supplied to the process chamber 11 as an inert gas g1 etc. as a carrier gas, for example. Further, by repeatedly depositing an organic material, an organic thin film composed of other film forming components is laminated.

Description

Formation method of organic thin film {METHOD FOR FORMING ORGANIC THIN FILM}

The present invention relates to a method for forming an organic thin film, and more particularly to a method for forming an organic thin film which is suitably used for forming an organic thin film constituting an optical element such as an organic EL element.

An organic EL device using an electroluminescence (hereinafter referred to as EL) of an organic material is formed by sandwiching an organic layer between an anode and a cathode. In the organic EL device having such a configuration, it is possible to obtain a light emitting device that emits light in each color by selecting the material of the organic layer, and by forming the light emitting devices emitting light in each color in a predetermined state, multi-color display or full color display. It is possible to configure a display device that can be used.

By the way, in manufacture of such an organic electroluminescent element, formation of the organic layer by the vacuum vapor deposition method is performed. The vacuum deposition method is a method in which a deposition material is supplied to and deposited on the surface of the substrate by evaporating the deposition material from the evaporation source in a state in which the substrate is disposed to face the evaporation source above the evaporation source. In order to control the film formation rate in the film formation by the vacuum deposition method, the evaporation rate of the evaporation material must be changed by changing the temperature of the evaporation source or the like. However, since the temperature and the evaporation rate do not correspond to the linearity and the evaporation rate is unstable by changing the temperature, accurate control is difficult. In addition, since the responsiveness of the evaporation rate to the temperature change is also deteriorated, there is also a problem that long process time is required and productivity is deteriorated.

Therefore, as a film forming method replacing the vacuum vapor deposition method, an organic vapor phase deposition method (OVPD method) has been proposed (Japanese Patent Publication No. 2001-523768 and Japanese Patent Publication No. 2000-504298). . As disclosed in this publication, the OVPD method supplies a plurality of organic precursors to the gas phase in a reactor in which a substrate is accommodated to react with these organic precursors, and deposits the organic compounds produced by the reaction on the surface of the substrate to form an organic compound. It is a method of forming a thin film. At this time, the reaction of the organic precursor may be a chemical reaction or a mixture of a plurality of organic precursors, and the organic precursors may be a donor / receptor relationship or a guest / host relationship.

In such an OVPD method, since the film formation rate is adjusted by the supply rate of the organic precursor to the reactor, the controllability of the film formation rate is good and the film formation rate is also faster than the vacuum deposition method.

By the way, formation of the organic thin film by the OVPD method had the following problems. That is, in the OVPD method, since a plurality of kinds of organic precursors are supplied into the reactor and reacted (chemical reaction or mixing) in the reactor, the mixed state of the organic precursors in the reactor is uneven or mixed. Even if uniform, when there is a fluctuation in the temperature distribution in the reactor, the reaction (chemical reaction) becomes nonuniform. This tends to cause variation in the film quality of the organic thin film formed in the substrate surface.

In addition, heat of reaction may be generated by the reaction of the organic precursor, and the organic thin film already formed on the substrate is degraded by the influence of the heat of reaction. Therefore, when the OVPD method is applied to the production of an organic EL device which forms an organic layer including a light emitting layer by laminating a plurality of organic films as described above, the organic film in the lower layer is deteriorated under the influence of the above-described reaction heat, and thus the device characteristics are excellent. It was hard to get.

Therefore, an object of the present invention is to provide a method for forming an organic thin film which does not generate heat on the film formation surface and is capable of forming an organic thin film having a uniform film quality in the substrate surface.

1 is a block diagram of a film forming apparatus for carrying out the method for forming an organic thin film of the present invention.

2 is a cross-sectional view showing an example of the configuration of an organic EL device manufactured by applying the present invention.

3 is a cross-sectional view showing a first example of the layer structure of the light emitting layer of the organic EL device obtained by applying the present invention.

4 is a cross-sectional view showing a second example of the layer structure of the light emitting layer of the organic EL device obtained by applying the present invention.

5 is a cross-sectional view showing a third example of the layer structure of the light emitting layer of the organic EL device obtained by applying the present invention.

The method for forming the organic thin film of the present invention for achieving the above object generates a gas in which a single film forming component made of an organic material is vaporized, is transported and supplied into the processing chamber in which the substrate is housed, and the surface of the substrate in the processing chamber. It is a method of depositing the organic material which hold | maintained the film-forming component in the film.

In such a method of forming an organic thin film, only a single film forming component made of an organic material transported and supplied into the processing chamber is retained and deposited on the substrate surface. For this reason, the nonuniformity of film-forming component mixing does not arise in the surface of a board | substrate, and reaction heat by reaction of film-forming components does not generate | occur | produce.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the formation method of the organic thin film of this invention is described in detail based on drawing.

<Film forming device>

1 is a schematic view showing an example of a film forming apparatus used for forming an organic thin film of an embodiment. The film-forming apparatus 1 shown in this figure is equipped with the processing chamber 11 for accommodating the board | substrate W in which the formation process of an organic thin film is performed.

This processing chamber 11 is equipped with the exhaust system 12, and the inside is controlled by predetermined pressure. Although not shown here, the gas exhausted by the exhaust system 12 traps excess material through the trap, and is configured such that only the inert gas (for example N ₂ ) described below is discharged out of the apparatus, The exhaust is configured to open to the atmosphere after passing through the scrubber.

In the processing chamber 11, a substrate support 13 for supporting the substrate W is housed, and a temperature control mechanism is provided as far as possible to control the temperature of the substrate W in a state supported by the substrate support 13. At the same time, a drive mechanism for rotating or sliding the held substrate W in its surface may be provided.

Moreover, the load lock chamber 14 for performing the operation which fixes the board | substrate W to the board | substrate support stand 13 is provided in this process chamber 11. The load lock chamber 14 is configured to be capable of evacuating the inside with a pump and possibly replaced with an inert gas, and to fix the substrate W to the substrate support 13 in an inert gas atmosphere. The substrate support 13 on which the substrate W is fixed is opened by opening the gate valve (not shown) between the load lock chamber 14 and the processing chamber 11 in a state where the pressure is reduced and the pump is exhausted. Can be stored in a predetermined state.

Moreover, the supply pipe line 21 which supplies the gas G in the process chamber 11 is connected to the process chamber 11. The gas inlet 21a, which is the tip end of the supply pipe line 21, is inserted into the processing chamber 11 and is directed toward the substrate holding surface of the substrate support 13 arranged and stored in the processing chamber 11 in a predetermined state. ) Is set to take out.

On the other hand, the other end of the supply pipe line 21 is connected to a gas purification device 22 (or cylinder) such as high purity inert gas (for example, N ₂ , He, Ar) or hydrogen, which is a carrier gas. The pressure regulator 23, the mass flow controller (MFC) 24, and the raw material are supplied to the supply pipe line 21 between the gas purification device 22 and the processing chamber 11 in order from the gas purification device 22 side. The supply mechanism 25 is provided, the vent line 26 is connected, and the valve V1 is formed between the vent line 26 and the processing chamber 11. In addition, the valve V2 is also formed in the vent line 26.

Among these, the raw material supply mechanism 25 branches from the raw material container 25a in which the organic material used as the raw material of the organic thin film is stored, the introduction pipe 25b branched from the supply pipe line 21, and inserted into the raw material container 25a. The discharge pipe 25c branched from the supply line 21 downstream from the pipe 25b and inserted into the raw material container 25a is provided. And between the introduction pipe 25b and the discharge pipe 25c in the supply pipe line 21, valve | bulb V3, V4, V5 is formed in the introduction pipe 25b and the discharge pipe 25c, respectively. have.

In the film forming apparatus 1 having the above configuration, all of the pipes, containers, and the like from the mass flow controller 24 to the processing chamber 11 are temperature controlled to a predetermined high temperature. The heating method for temperature control may be an air thermostat system installed in an oven, a system for circulating high temperature oil or the like, an RF heating (Radio Frequency heating: high frequency induction heating) system or a lamp heating system, and is not particularly limited.

<Formation method of organic thin film>

Next, the formation method of the organic thin film using the film-forming apparatus 1 of the above structure is demonstrated. Here, as an example, an embodiment in the case of forming an electron transporting light emitting layer made of Alq3 [tris (8-quinolinolato) aluminu (III)] generally used in organic EL devices will be described.

First, in the load lock chamber 14, the board | substrate W is hold | maintained and fixed to the board | substrate support 13, the inside of the load lock chamber 14 was pressure-reduced, and the load lock chambers maintained at substantially the same pressure, respectively ( The gate between 14 and the processing chamber 11 is opened to set the substrate support 13 to a predetermined position in the processing chamber 11. At this time, the inside of the load lock chamber 14 and the inside of the processing chamber 11 are maintained at 133 Pa, for example. And the board | substrate W is hold | maintained about 20 degreeC by the temperature control mechanism of the board | substrate support stand 13. When the substrate support 13 is provided with a rotation or slide mechanism, the substrate W is rotated by this mechanism, whereby film formation with a uniform film thickness is performed.

On the other hand, in the raw material container 25a of the raw material supply mechanism 25, the organic material which becomes a raw material of an organic thin film (here Alq3) is stored, and the organic material in the raw material container 25a is 280 degreeC in predetermined temperature (Alq3). Heat). Thereby, in the raw material container 25a, the vapor pressure fraction of the organic material Alq3 with respect to heating temperature is made to exist as a gas. In addition, the piping, the container, etc. from the mass flow controller 24 to the processing chamber 11 shall all be heated by temperature control (for example, about 280 degreeC) at predetermined high temperature.

In the above state, the valves V2 and V3 are closed, and the valves V1, V4 and V5 are opened. Then, the inert gas (for example, N ₂ ), which is pressure-controlled by the pressure regulator 23 from the high purity gas purification device 22 to 0.2 MPa, and flow-controlled with high precision by the mass flow controller 24 ( g1) flows into the supply pipe line 21. An example of the flow rate is 1000 sccm (standard cc / min: flow rate per minute in a standard state). Then, the inert gas g1 is supplied to the raw material container 25a, the gas of the organic material Alq3 vaporized in the raw material container 25a is used as the film forming component gas g2, and the inert gas g1 is the carrier. The gas is transported and supplied from the discharge pipe 25c and the supply pipe line 21 into the processing chamber 11.

Thereby, the gas containing the organic material (Alq3) gas as the film-forming component gas g2 from the gas inlet 21a toward the board | substrate W fixedly held by the board | substrate support stand 13 in the process chamber 11 ( G) is supplied. Then, the organic material Alq3 is deposited on the surface of the substrate W maintained at a temperature of 20 ° C. in the state of retaining its components to form an organic thin film made of Alq3.

At this time, the film thickness of the organic thin film is controlled by the supply time of the gas into the process chamber 11, the valves V1, V4, V5 are closed at the portion where the organic thin film having the predetermined film thickness is formed, and the valves V2, V3) is opened to stop the supply of the film forming component gas g2 into the process chamber 11, and the inside of the process chamber 11 is replaced with an inert gas g1.

After the above, the board | substrate W and the board | substrate support stand 13 are returned to the load lock chamber 14, the pressure in the load lock chamber 14 is returned to normal pressure, and the board | substrate W is taken out. At this time, so as not to contact with the atmosphere of organic thin film of the substrate (W) is formed, the load lock chamber 14 to move the substrate (W) with only the N ₂ gas-tight box, equipped, within and, N ₂ gas sealing film forming the box The device 1 may be taken out of the device.

In the above method of forming an organic thin film, only a single film forming component gas g2 made of an organic material is transported and supplied to the process chamber 11 together with an inert gas, and the organic material is formed on the surface of the substrate W accommodated in the process chamber 11. Is deposited on the surface of the substrate W while retaining the film forming component. For this reason, the nonuniformity of film-forming component mixing does not arise in the surface of the board | substrate W, and reaction heat by reaction of film-forming components does not generate | occur | produce. Therefore, it is possible to form an organic thin film having a uniform film quality in the surface of the substrate W without causing deterioration of the lower organic film due to reaction heat.

In the method for forming the organic thin film described above, the case where the single layer film Alq3 is formed on the surface of the substrate W has been described. However, in the case where a plurality of organic thin films are laminated on the substrate W, the process chamber ( Between the 11) and the gas purification device 22 (or the pressure regulator 23), a plurality of supply lines 21 provided with portions from the mass flow controller 24 to the valve V1 are provided to form a film forming apparatus. I use it. By using such a film-forming apparatus, the film-forming component gas which consists of different organic materials can be introduce | transduced into the process chamber 11 from the some supply line 21 one by one, and a plurality of organic thin films can be laminated | stacked continuously.

Next, as an example of such continuous film formation of a plurality of organic thin films, an embodiment in which the method for forming an organic thin film of the present invention is applied to the manufacture of an organic EL element will be described.

2 is a cross-sectional view showing an example of the configuration of an organic EL element. The organic EL element 100 has a structure in which the first electrode 101, the organic layer 102, and the second electrode 103 are sequentially stacked on a substrate W made of glass or the like. The first electrode 101 is used as an anode (or cathode), and the second electrode 103 is used as a cathode (or anode) in pairs with the first electrode 101.

The organic layer 102 sequentially moves from the anode side (here, for example, the first electrode 101 side) from the anode side (here, for example, the second electrode 103 side) to the hole injection layer 102a. And an organic thin film such as a hole transport layer 102b, a light emitting layer 102c, an electron transport layer 102d or an electron injection layer 102e. Each of these layers (organic thin film layers) 102a to 102e is formed in a pattern using a different material for each light emitting color of the light emitting element 5. In addition, the organic layer 102 is not limited to such a layer structure, If it is a structure which has a light emitting layer at least, a laminated structure as needed can be selected.

In addition, the organic EL element 100 formed on the board | substrate W is sealed by the protective film, sealing agent, etc. which abbreviate | omitted illustration here.

In manufacture of the organic electroluminescent element 100 of such a structure, the formation method of the organic thin film mentioned above is applied to formation of each organic thin film layer 102a-102e which comprises the organic layer 102. At this time, in the film forming apparatus 1 described with reference to FIG. 1, the organic thin film layers 102a to 102e can be formed continuously by using the film forming apparatus provided with a plurality of supply lines.

In particular, in the case where each organic thin film layer 102a to 102e is a structure in which another organic material is added as a dopant to an organic material serving as a host, the host layer and the dopant layer are continuously formed to be delta-doped in the host material. Each organic thin film layer 102a to 102e to which the dopant is added may be laminated.

In this case, since the host layer and the dopant layer are each formed uniformly without affecting the lower layer as described above, the host layer and the dopant layer are adjusted by adjusting the film thickness between the host layer and the dopant layer. It is possible to form each organic thin film layer 102a-102e excellent in controllability with a punctual density adjusted with high precision in the inside of a board | substrate.

Further, by adjusting the film thickness of the host layer and the dopant layer, since the dopant concentration is adjusted with high precision within the substrate plane, the degree of freedom in designing the organic thin film layers 102a to 102e (that is, the design of the organic EL element) Degrees of freedom).

For example, as shown in Fig. 3, a host layer A having a predetermined film thickness is provided in contact with an interface between the upper and lower layers, and a dopant layer B is formed between the host layers A to form the host. It is possible to form an organic thin film layer (for example, the light emitting layer 102c) in which the dopant is added only to the center portion, whereby concentration quenching caused by the dopant being too close can be avoided.

In addition, since the light emitting portion in the light emitting layer 102c can be controlled at the position of the dopant layer, deterioration of the device due to self-luminous can also be suppressed.

In addition, as in FIG. 4, by changing the film thickness of the dopant layer B between the host layers A, the amount of the dopant in the position close to the interface with the lower layer is reduced, and the position of the position close to the interface with the upper layer is reduced. The dopant amount is increased, or vice versa, and the degree of freedom of high design is increased.

In addition, although the film thickness of the dopant layer B between the host layers A is constant like FIG. 5, the effective dopant concentration can be controlled by controlling the thickness of the host layer A. FIG. This point can increase the degree of freedom in designing an organic EL device as in the case of FIG.

In addition, each organic thin film layer 102a to 102e is patterned with each pixel on the substrate W. FIG. For this reason, in the continuous film formation of each organic thin film layer 102a-102e using the said film-forming apparatus, the mask which has an opening part for every pixel facing the film-forming surface of the board | substrate W is arrange | positioned, and gas is introduced through this mask opening part. The gas G introduced into the process chamber 11 from the sphere 21a is supplied to the surface of the substrate W. As shown in FIG.

In this case, unlike the vacuum vapor deposition method, the formation method of the organic thin film mentioned above enables the supply direction of film-forming component gas, and it does not need to face down the film-forming surface of a board | substrate. Therefore, the film formation surface (and mask) of a board | substrate can be arrange | positioned substantially perpendicularly, and an organic thin film can be formed, and the bending of the mask arrange | positioned facing the film formation surface can be prevented.

In addition, in the film-forming apparatus 1 demonstrated using FIG. 1, the gas introduction port 21a is provided in multiple numbers, and it arrange | positions evenly with respect to the film-forming surface of the board | substrate W, and the structure of the surface of the board | substrate W is carried out. The gas G can be supplied to each part from the same direction. For this reason, in the vacuum evaporation method, although the variation in the formation precision of the organic thin film pattern was caused by the shadow effect in the case of using a mask, it is also possible to solve such a problem. In addition, since the film forming apparatus is formed at a uniform film thickness with respect to the surface of the substrate W, it is not necessary to slide or rotate the substrate support 13 so that the apparatus structure can be miniaturized.

As described above, according to the method for forming the organic thin film of the present invention, the film forming component is formed by supplying only a single film forming component gas made of an organic material into the processing chamber and maintaining the film forming component to deposit the organic material on the substrate surface. It becomes possible to form an organic thin film without the mixing nonuniformity or the reaction heat by reaction of film-forming components. Therefore, it becomes possible to form an organic thin film with a uniform film quality without causing deterioration of the lower organic film due to reaction heat. As a result, when this optical thin film formation method is applied and an optical element like an organic EL element is formed, it becomes possible to obtain the element with a favorable characteristic.

Claims (4)

Gas generated by vaporizing a single film forming component made of an organic material, Transporting and supplying the gas into a processing chamber containing a substrate; A method of forming an organic thin film, comprising depositing an organic material retaining the film formation component on a surface of a substrate in the processing chamber. The method of forming an organic thin film according to claim 1, wherein the substrate is cooled when the organic material is deposited. The method for forming an organic thin film according to claim 1, wherein another film forming component is laminated by repeatedly depositing the organic material. The method of forming an organic thin film according to claim 1, wherein the gas is transported and supplied into the processing chamber using a carrier gas.