JP2004119064A - Thin film forming device and thin film forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film forming device and thin film forming method for forming a thin film such as an organic thin film in a desired shape and thickness on an object to be formed such as a substrate. <P>SOLUTION: In the thin film forming device 1, a first shadow mask 6 is made close to or in contact with the substrate 2, and a second shadow mask 7 is arranged so as to maintain a certain distance from the first shadow mask 6. In forming the organic thin film, the first shadow mask 6 is fixed, and only the second shadow mask 7 with an opening part formed is moved so that deposition material reaches to a specific group of opening parts of the first shadow mask 6. A predetermined organic thin film is formed in a predetermined region on the substrate 2 by appropriately changing positional relation between the first and second shadow masks 6, 7. In the thin film forming device 1, entering of the deposition material after the first shadow mask 6 passes is suppressed, and damage and transfer of the formed organic thin film with movement of the second shadow mask 7 is prevented. Thereby, the organic thin film of a predetermined shape and thickness is formed in the predetermined region on the substrate 2. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a thin film forming apparatus and a thin film forming method, and more particularly to a thin film forming apparatus and a thin film forming method for forming a thin film on an object to be formed, such as formation of a light emitting layer of an organic EL (Electro-Luminescence) element.
[0002]
[Prior art]
Organic EL devices have attracted attention as large-area light-emitting devices that emit light at a low voltage of 10 V or less since the report of a stacked device in which a hole transport layer and an electron transport layer formed of a thin film of an organic compound (organic thin film) are stacked. I have. The stacked organic EL element basically has a structure in which anode, hole transport layer, light emitting layer, electron transport layer, and cathode layers are stacked. Among them, the light emitting layer may be configured so that the hole transport layer or the electron transport layer also has the function.
[0003]
As the anode of such an organic EL element, gold (Au), tin oxide (SnO) ₂ ), Indium-tin oxide (ITO), or other metal materials having a large work function or electrically conductive materials are often used. In particular, ITO is widely used as an anode material because it has a high transmittance in a visible region and enables surface light emission from a light emitting layer. On the other hand, as the cathode, an aluminum-lithium (Al-Li) alloy, a magnesium-indium (Mg-In) alloy, a magnesium-aluminum (Mg-Al) alloy, a magnesium (Mg) alloy or the like having a high chemical stability is used. A material or an alloy material in which these are co-deposited is used.
[0004]
Each of the hole transport layer, the light-emitting layer, and the electron transport layer constituting the organic EL element is an organic thin film, and the emission color of the organic EL element differs depending on the type and combination of the materials. In forming an organic EL device, various organic materials or organometallic materials are used as raw materials of the organic thin film. In particular, for forming a low-molecular organic EL device using a material having a molecular weight of about 200 to 300, As one of the basic technologies, a vacuum deposition method is widely used. Vacuum deposition of organic materials and organic metal materials involves passing a large current through a metal boat such as tungsten (W), molybdenum (Mo), or tantalum (Ta), which has high electrical resistance, and vaporizing the material by the heat generated at that time. In general, a mechanism for depositing on a substrate is used.
[0005]
By the way, a display panel using an organic EL element (hereinafter referred to as an “organic EL display panel”) generally has a structure in which a plurality of pixels of a single color or different emission colors are arranged in a matrix on a panel substrate. Have.
[0006]
FIG. 10 is a diagram showing an example of the arrangement of pixels of the organic EL display panel.
For example, in the case of an organic EL display panel having a plurality of pixels having different emission colors, the organic EL elements 100 of each emission color of red (R), green (G), and blue (B) are arranged on a panel substrate. , It is possible to perform multi-color display. The emission color of the organic EL element 100 differs depending on the material configuration as described above. Therefore, in manufacturing an organic EL display panel, it is necessary to form the organic EL elements 100 of the respective emission colors at predetermined positions on the panel substrate, that is, so-called “separation”.
[0007]
In general, a shadow mask having an opening in a region corresponding to an organic thin film forming position of an organic EL element of the same luminescent color is used for this coating. Then, the shadow mask is brought into close contact with or close to the panel substrate, and after forming an organic thin film of a certain luminescent color, the shadow mask is moved a predetermined distance to form an organic thin film of another luminescent color, and so on. , Green and blue pixels.
[0008]
In this separate coating, if the shadow mask is merely brought close to the substrate, the deposition material after passing through the shadow mask goes to a region other than the region where the organic thin film is to be formed on the substrate, so that the boundary is blurred. Such a problem may occur. However, when the shadow mask is used in close contact with the substrate, the shadow mask is pressed against the already formed organic thin film as the shadow mask moves, and the organic thin film is transferred to the shadow mask and becomes a defect. There was a case. In addition, the organic material attached to the shadow mask may be transferred to another location on the substrate, resulting in a defect. Conventionally, in order to solve the problem associated with the movement of the shadow mask, a partition wall separating the elements is formed on the substrate using a polymer material such as a resist to avoid direct contact between the shadow mask and the substrate. Methods have been proposed. (For example, refer to Patent Document 1.)
[0009]
[Patent Document 1]
JP-A-8-315981
[0010]
[Problems to be solved by the invention]
However, in the production of an organic EL display panel using partition walls, moisture contained in a polymer material forming the partition walls or a residue of an organic solvent used in photolithography is leached from the partition walls. In the vicinity, there is a problem that the thin film material may be deteriorated. The region where the thin film material is degraded becomes a non-light-emitting region in the pixel, causing uneven light emission of the organic EL display panel.
[0011]
Furthermore, by using a polymer material for the partition walls, it is not possible to use an organic solvent such as acetone or isopropyl alcohol, which has a high cleaning effect, in the substrate cleaning step before the organic thin film deposition process, thereby completely eliminating organic contamination on the substrate. There is a problem that cannot be removed. Usually, this substrate cleaning step is performed after forming a transparent electrode (anode) on the substrate, so that residual organic contamination causes a decrease in the work function of the transparent electrode and a decrease in the yield of the organic EL display panel. There are cases.
[0012]
In addition, by using the partition walls, the contact between the shadow mask and the substrate can be avoided.However, depending on the formation conditions, the formed organic thin film has a thicker cross-sectional shape at the center, depending on the forming conditions. The edges may be thinner. As described above, when the thickness of the organic thin film in the organic EL element becomes non-uniform, the current density distribution becomes non-uniform, which causes uneven light emission.
[0013]
Further, since a process for forming the partition on the substrate is added, the manufacturing process of the organic EL display panel becomes longer, and the cost becomes higher.
The present invention has been made in view of such a point, and a thin film forming apparatus and a thin film forming method for forming a thin film such as an organic thin film in a desired shape and thickness on an object to be formed such as a substrate. The purpose is to provide.
[0014]
[Means for Solving the Problems]
In the present invention, in order to solve the above-mentioned problem, a thin film forming apparatus realized by the configuration example shown in FIG. 1 is provided. The thin film forming apparatus of the present invention is a thin film forming apparatus in which a vapor deposition material is heated and vaporized by a vapor deposition source, and the vaporized vapor deposition material is deposited on a workpiece to form a thin film. A first shadow mask having an opening group formed so as to be deposited in a region where the thin film is to be formed, and an opening formed so that the deposition material reaches a part of the opening group; And a second shadow mask having a portion.
[0015]
According to the thin film forming apparatus 1 illustrated in FIG. 1, the first shadow mask 6 has an opening group through which the deposition material can reach all regions of the substrate 2 where an organic thin film is to be formed. On the other hand, the second shadow mask 7 has an opening formed so that the deposition material reaches a part of the opening group of the first shadow mask 6. The second shadow mask 7 limits an area where the first shadow mask 6 can form an organic thin film on the substrate 2 at a specific opening of the opening group of the first shadow mask 6. Only at this time, an organic thin film is formed.
[0016]
After the formation of the organic thin film, for example, the second shadow mask 7 is moved so that the deposition material reaches the other part of the opening group of the first shadow mask 6. As a result, another organic thin film can be formed on the substrate 2 in the other part, and the organic EL elements are formed separately on the substrate 2.
[0017]
In the thin film forming apparatus 1, the first shadow mask 6 is fixed, while the second shadow mask is arranged at a certain distance from the first shadow mask 6, for example. This prevents the organic thin film already formed by the first shadow mask 6 from being damaged or transferred to another pixel region during the separate coating, and the movement by the second shadow mask 7 does not occur. At this time, no damage or transfer of the organic thin film occurs.
[0018]
Further, according to the present invention, in a thin film forming method in which a vapor deposition material is heated and vaporized by a vapor deposition source, and the vaporized vapor deposition material is deposited on a workpiece to form a thin film, the vapor deposition material includes the thin film on the workpiece. Arranging a first shadow mask having an opening group formed so as to be deposited in a region in which is to be formed, and forming the first shadow mask so that the deposition material reaches a part of the opening group. Arranging a second shadow mask having an opened portion, heating and vaporizing the vapor deposition material by the vapor deposition source, and depositing the vaporized vapor deposition material on the object to be formed in the part, thereby forming the thin film. And a step of forming a thin film.
[0019]
According to such a thin film forming method, a region where a thin film can be formed by the first shadow mask is limited by the second shadow mask, and a specific opening of the opening group of the first shadow mask is defined. The thin film is formed only on the object in the portion. Thus, a thin film having a predetermined shape and thickness can be formed in a predetermined region on the object.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, taking the formation of an organic EL element of an organic EL display panel as an example.
[0021]
FIG. 1 is a diagram showing a configuration example of a thin film forming apparatus.
The thin film forming apparatus 1 has a vapor deposition chamber 3 in which a substrate 2 on which an organic EL element is formed is disposed. The vapor deposition chamber 3 is provided with an exhaust mechanism 4 for depressurizing the inside. I have. Here, the substrate 2 disposed in the vapor deposition chamber 3 is a substrate in which an ITO electrode functioning as a transparent electrode (anode) is patterned on a glass in a stripe shape or an island shape (hereinafter, referred to as an “ITO substrate”). ), And this ITO substrate becomes an organic thin film-formed object.
[0022]
In the vapor deposition chamber 3, a vapor deposition source 5 having a boat for heating and vaporizing an organic material or an organic metal material, which is a raw material of an organic thin film constituting an organic EL element, by applying an electric current is disposed to face the substrate 2. Have been.
[0023]
Between the substrate 2 and the evaporation source 5, a first shadow mask 6 and a second shadow mask 7 made of metal, each having an opening in a predetermined region, are arranged in this order from the substrate 2 side. ing. As a material of the first and second shadow masks 6 and 7, for example, nickel (Ni) and a nickel-iron (Ni-Fe) alloy are used, respectively.
[0024]
These first and second shadow masks 6 and 7 can be moved in the vapor deposition chamber 3 in parallel with the plane of the substrate 2 or perpendicular to the plane of the substrate 2 by the mask moving mechanism unit 8 including a servo or the like. It has become. When the organic thin film is formed, the first shadow mask 6 is positioned in a parallel direction by a positioning mechanism 9 described later by the mask moving mechanism 8, and then is moved in a vertical direction until the first shadow mask 6 comes into a state of approaching or contacting the substrate 2. Is to be moved to. Then, that state is maintained until the deposition is completed. Also, after the second shadow mask 7 is similarly positioned in the parallel direction by the positioning mechanism 9, the second shadow mask 7 is moved in the vertical direction while maintaining a fixed distance with the first shadow mask 6 or until it comes into contact with the first shadow mask 6. ing.
[0025]
FIG. 2 is a schematic plan view of the first shadow mask. FIG. 3 is a schematic plan view of the second shadow mask, in which (a) a case where each opening is arranged independently, and (b) a case where the openings are arranged in a slit shape. Each is shown. 2 and 3, alignment marks for positioning, which will be described later, are not shown.
[0026]
The first shadow mask 6 shown in FIG. 2 has independent openings 60 at positions corresponding to all the organic EL elements to be formed on the substrate 2 in FIG. The shape of the opening 60 is substantially the same as the shape of the organic thin film to be formed. It is preferable that the thickness of the first shadow mask 6 be about 20 μm to 100 μm. This is because if the thickness is too thin, the strength as a shadow mask cannot be sufficiently maintained, and further, if the thickness of the organic thin film to be formed is large, the vapor deposition material is also applied to the edge of the opening on the first shadow mask 6. Is deposited, and defects or defects may occur during removal. If the thickness of the first shadow mask 6 is large, the first shadow mask 6 is deposited up to the side wall of the opening 60 of the first shadow mask 6 which is close to or in contact with the substrate 2 when the organic thin film is formed, so that the thickness of the organic thin film becomes uneven. Is caused. As described above, the thickness of the first shadow mask 6 is appropriately set in consideration of the thickness of the organic thin film to be formed and its uniformity, or its own weight.
[0027]
On the other hand, the second shadow mask 7 has fewer openings 70 than the first shadow mask 6, as shown in FIG. The openings 70 of the second shadow mask 7 are arranged such that the vapor deposition material reaches only a specific group of openings of the first shadow mask 6, for example, a group of openings corresponding to a formation position of a red element. Is formed. That is, the second shadow mask 7 is used for the purpose of limiting the range of the organic thin film that can be formed by the first shadow mask 6. Therefore, the thickness is not particularly limited as long as the deposition material can accurately reach the specific opening group of the first shadow mask 6.
[0028]
The shape of the opening 70 of the second shadow mask 7 is similar to the shape of the opening of the first shadow mask 6 as shown in FIG. It is formed as follows. Alternatively, as shown in FIG. 3B, the opening may be a slit-shaped opening 70 corresponding to a specific opening group of the first shadow mask 6, as shown in FIG. 3B. When the opening 70 is formed in a slit shape as described above, any one of the row direction and the column direction of the organic EL elements formed in parallel may be selected as the slit direction.
[0029]
Here, the size of the opening 70 of the second shadow mask 7 in FIG. 3A does not need to be the same as the size of the opening 60 of the first shadow mask 6, and the first size is within a certain range. The shadow mask 6 can be formed to have a size larger than the opening 60.
[0030]
FIG. 4 is a view showing an opening of the first shadow mask. Here, the dimension of the short side of one opening of the first shadow mask 6 is X1, the interval to the adjacent opening in the short side direction (X1 dimension direction) is X2, and the dimension of the long side of the opening is X1. The distance between Y1 and the adjacent opening in the long side direction (Y1 dimension direction) is Y2. At this time, the opening dimensions X3, Y3 of the short side and the long side that can be taken by one opening of the second shadow mask 7 can be expressed by the following equations (1) and (2). .
[0031]
(Equation 1)
X1 ≦ X3 <X1 + X2 (1)
[0032]
(Equation 2)
Y1 ≦ Y3 <Y1 + Y2 (2)
Further, when the second shadow mask 7 has a slit-shaped opening continuous in the long side direction, the number of pixels included in the region corresponding to one slit-shaped opening, That is, assuming that the number of openings arranged in the Y1 dimension direction of the first shadow mask 6 is n, the opening dimension Y3 can be expressed by the following equation (3).
[0033]
[Equation 3]
Y1 ≦ Y3 <n (Y1 + Y2) −Y2 (3)
Therefore, the shape and arrangement of the opening of the first shadow mask 6 are determined by the shape and arrangement of the organic EL element to be formed on the substrate 2, and the shape and arrangement of the second shadow mask 7 are further determined according to the shape and arrangement. The shape and arrangement are determined.
[0034]
The first and second shadow masks 6 and 7 and the substrate 2 are engraved with alignment marks for appropriately setting the respective positional relationships when forming the organic thin film. In the thin film forming apparatus 1 shown in FIG. 1, the positioning of the substrate 2 and the first and second shadow masks 6 and 7 can be performed by the positioning mechanism 9.
[0035]
FIG. 5 is an explanatory diagram of a method of positioning the substrate and the first and second shadow masks. However, FIG. 5 shows a state in which the substrate 2 and the first and second shadow masks 6 and 7 are positioned as viewed from the substrate 2 side, and the openings of the first and second shadow masks 6 and 7 are shown. The part and the ITO electrode on the substrate 2 are not shown.
[0036]
The substrate 2 and the first shadow mask 6 are each provided with an alignment mark 11 for positioning them. Similarly, alignment marks 12 for positioning the first shadow mask 6 and the second shadow mask 7 are respectively engraved.
[0037]
When positioning the substrate 2 and the first and second shadow masks 6 and 7, first, the substrate 2 is set at a predetermined position of the thin film forming apparatus 1. Then, the first shadow mask 6 is moved by the mask moving mechanism 8 in parallel with the plane of the substrate 2, and positioned so that the alignment marks 11 of the substrate 2 and the first shadow mask 6 are aligned. At this time, the positioning mechanism unit 9 performs appropriate image processing on the image of the alignment mark 11 obtained using a CCD (Charge Coupled Device) or the like, and controls the servo of the mask moving mechanism unit 8 based on the processing result. Operate so that both are accurately positioned. After the positioning of the substrate 2 and the first shadow mask 6, the first shadow mask 6 is moved vertically to the substrate 2 side to approach or contact the substrate 2. At this time, the moving distance in the vertical direction is set beforehand from the position of the first shadow mask 6 at the time of positioning to a distance necessary for bringing the first shadow mask 6 close to or in contact with the substrate 2. Make it move.
[0038]
Subsequently, the second shadow mask 7 is moved in parallel with the plane of the substrate 2, and positioning is performed so that the alignment marks 12 with the first shadow mask 6 are aligned. At that time, the positioning mechanism 9 performs appropriate image processing on the image of the alignment mark 12 obtained by using a CCD or the like, and operates the servo or the like of the mask moving mechanism 8 based on the processing result. Make sure it is positioned correctly. After the positioning, the second shadow mask 7 is kept at a predetermined distance between the first and second shadow masks 6 and 7, or the first and second shadow masks 6 and 7 are brought into contact with each other. 1 is moved vertically to the shadow mask 6 side. In this case, the moving distance in the vertical direction is set in advance to a distance necessary for disposing a predetermined distance or making contact with the same as in the case of the first shadow mask 6. .
[0039]
After positioning and arranging the first and second shadow masks 6 and 7 in this way, an organic thin film is formed. In the thin film forming apparatus 1, the operations of the exhaust mechanism 4, the evaporation source 5, the mask moving mechanism 8, and the positioning mechanism 9 are controlled by the control unit 10, respectively.
[0040]
FIG. 6 is a schematic side view of the substrate and the first and second shadow masks when the organic thin film is formed, and shows (a) an initial state and (b) a state after the movement of the second shadow mask, respectively. However, FIG. 6 illustrates a case where the first shadow mask 6 is arranged in contact with the substrate 2 and the first and second shadow masks 6 and 7 are arranged in a non-contact state. . FIG. 6 shows a case where the opening of the second shadow mask 7 is formed larger than the opening of the first shadow mask 6.
[0041]
In the initial state after the positioning, as shown in FIG. 6A, the first shadow mask 6 has the openings 60a, 60b, and 60c arranged on the stripe-shaped or island-shaped ITO electrodes 2a of the substrate 2. So as to be in contact with the ITO electrode 2 a of the substrate 2. In the initial state, the opening 70a of the second shadow mask 7 corresponds to the opening 60a of the first shadow mask 6, and the second shadow mask 7 is kept in a non-contact state with a certain distance from the first shadow mask 6. Are located.
[0042]
When forming the organic thin film, first, the organic thin film 13 is formed in the initial state shown in FIG. At that time, the vaporized material vaporized from the vapor deposition source 5 shown in FIG. 1 passes through the opening 70a of the second shadow mask 7, and then the first shadow mask disposed corresponding to the opening 70a. 6 reaches the opening 60a. Thereby, an organic thin film 13 such as a red light-emitting material of an organic EL element is formed on the ITO electrode 2a of the substrate 2.
[0043]
On the other hand, in the initial state, the vapor deposition material does not reach the openings 60b and 60c of the first shadow mask 6 which do not correspond to the openings 70a of the second shadow mask 7, and the ITO material 2a is not deposited on the ITO electrode 2a. The organic thin film 13 is not formed.
[0044]
When another organic thin film 14 is formed on the ITO electrodes 2a in the openings 60b and 60c where the organic thin film 13 is not formed, as shown in FIG. 6B, the first shadow mask 6 Only the second shadow mask 7 is moved while being fixed at the initial position. At this time, the second shadow mask 7 is moved in parallel with the plane of the substrate 2, and the opening 70a is arranged so as to correspond to the opening 60b. The moving distance of the second shadow mask 7 is set in advance from the position in the initial state after positioning to the position corresponding to the adjacent opening 60b, and the mask moving mechanism shown in FIG. Move with 8.
[0045]
By arranging the openings 70a and 60b in a corresponding manner, another organic thin film 14 such as a green light-emitting material can be formed in the opening 60b. On the other hand, the vapor deposition material does not reach the opening 60c and the opening 60a in which the organic thin film 13 has already been formed on the ITO electrode 2a.
[0046]
Similarly, only the second shadow mask 7 is moved in parallel from the state shown in FIG. 6B so as to correspond to the opening 70a, and the openings 60a and 60b are formed in the second shadow mask. Mask with a mask 7. Then, for example, a blue light-emitting material may be deposited on the ITO electrode 2a in the opening 60c.
[0047]
As described above, the organic thin film is formed by the thin film forming apparatus 1 in a predetermined shape and thickness on a predetermined region on the substrate 2 while appropriately changing the positional relationship between the first and second shadow masks 6 and 7. It is performed by forming.
[0048]
In this organic thin film formation, the first shadow mask 6 can be arranged in a state of being close to the substrate 2, but is desirably arranged in contact with the substrate 2 as shown in FIG. This is because the first shadow mask 6 is in contact with the substrate 2, so that the deposition material after passing through the first shadow mask 6 is reliably prevented from flowing around and the contour of the organic thin film can be prevented from being blurred. This is because
[0049]
Further, in the formation of the organic thin film, the second shadow mask 7 can be arranged in contact with the first shadow mask 6, but can be arranged in a non-contact state as shown in FIG. desirable. This is because the first shadow mask 6 is fixed and only the second shadow mask 7 is moved in parallel, so that contact or transfer with the formed organic thin film due to the movement is prevented. However, depending on the area of the organic thin film to be formed, when the distance between the first and second shadow masks 6 and 7 is 1000 μm or more, the deposition material after passing through the second shadow mask 7 becomes There is a possibility that it goes around a wide range. In this case, the vapor deposition material is deposited on the substrate 2 in an unintended region, which may cause problems such as non-light emission. Therefore, it is preferable that the distance between the first and second shadow masks 6 and 7 is about 1000 μm at the maximum.
[0050]
Although not shown in FIG. 1, a sheet-like magnet is arranged on the surface of the substrate 2 disposed in the evaporation chamber 3 on the side opposite to the evaporation source 5 side, that is, on the back side of the substrate 2 where the organic thin film is not formed. It may be configured. In this case, the first shadow mask 6 made of metal is moved toward the substrate 2 after positioning with respect to the substrate 2, and is further attracted by the magnet. This ensures that the first shadow mask 6 comes into contact with the substrate 2 and that the contact state can be maintained until the deposition is completed.
[0051]
As described above, in forming an organic thin film by the thin film forming apparatus 1, the first shadow mask 6 is brought close to or in contact with the substrate 2, and the second shadow is kept at a certain distance from the first shadow mask 6. The mask 7 is arranged. During the formation of the organic thin film, the first shadow mask 6 is fixed, and the second shadow mask is provided with an opening so that the vapor deposition material reaches a specific group of openings of the first shadow mask 6. Move only 7
[0052]
As described above, since the first shadow mask 6 is brought close to or in contact with the substrate 2 and is not moved until the end of vapor deposition, damage of the formed organic thin film by the first shadow mask 6 and transfer to another position are required. Can be prevented. Furthermore, since the first shadow mask 6 is close to or in contact with the substrate 2, it is possible to suppress the evaporation material from passing through the first shadow mask 6 and to suppress contour blur. As a result, an organic thin film can be formed in a desired region with a high accuracy and a uniform thickness, and an organic EL element having a high performance and a high uniformity in a light emission area and a light emission luminance can be formed. Become.
[0053]
Further, by forming an organic thin film using such a thin film forming apparatus 1, it is possible to reduce the number of steps and costs as compared with the conventional formation of an organic EL element using partition walls, and to reduce the cost of manufacturing an organic EL display panel. I can do it.
[0054]
Next, an example of forming an organic EL element using the thin film forming apparatus 1 according to the present invention will be specifically described.
FIG. 7 is a diagram showing an example of a flow of forming an organic EL element. FIG. 8 is a view for explaining a light emitting layer forming step, in which (a) a red light emitting layer forming step, (b) a green light emitting layer forming step, and (c) a blue light emitting layer forming step. . However, in the description of this forming example and FIG. 8, the same elements as those shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.
[0055]
In the formation of the organic EL device, first, an ITO electrode 20b having a line width of 100 μm is patterned on a 0.7 mm-thick soda glass 20a into a stripe shape with a spacing of 20 μm by a method such as sputtering. (Step S1). The ITO electrode 20b is usually formed with a thickness of 20 nm or more. In particular, the thickness is preferably about 50 nm to 200 nm in consideration of the effect of increasing the conductivity by increasing the thickness of the ITO electrode 20b and the effect of increasing the light transmittance by decreasing the thickness of the ITO electrode 20b.
[0056]
Next, the ITO substrate 20 is cleaned in the order of a cleaning agent, pure water, an organic solvent 1, pure water, and an organic solvent 2 (step S2). Here, as the organic solvents 1 and 2, any of acetone, isopropyl alcohol, ethanol, methanol, benzene, toluene, and tetrahydrofuran can be used. The cleaned ITO substrate 20 is placed at a predetermined position in the vapor deposition chamber 3 provided in the thin film forming apparatus 1 (Step S3).
[0057]
Here, as the first shadow mask 6 used for forming the organic EL element, an opening is provided in all regions where an organic thin film is formed, and the long side direction of the opening is aligned with the ITO electrode 20b. And a thickness of 20 μm. The dimensions of the opening are 100 μm on the short side, 300 μm on the long side, 20 μm between the short sides of the adjacent opening, and 60 μm between the long sides of the adjacent opening.
[0058]
After the first shadow mask 6 is positioned with respect to the ITO substrate 20 by the positioning mechanism 9, the first shadow mask 6 is vertically moved toward the ITO substrate 20 and is arranged so as to be in contact with the ITO electrode 20b (step S4). .
[0059]
Then, the inside of the vapor deposition chamber 3 is evacuated and a predetermined degree of vacuum (for example, 10 ^-5 After the pressure is reduced to about Pa) (Step S5), an organic material or an organic metal material is vapor-deposited on the ITO electrode 20b of the installed ITO substrate 20 by a vacuum vapor deposition method, and first, the hole transport layer 21 is formed (Step S5). S6). The hole transport layer 21 is usually formed with a thickness of about 10 nm to 500 nm, preferably about 20 nm to 100 nm. When the film thickness is less than 10 nm, the light emitting portion may be close to the electrode portion and light emission may be quenched by the electrode. On the other hand, when the film thickness exceeds 500 nm, the driving voltage may increase. This is because there are cases where
[0060]
Examples of the organic material that can be used for forming the hole transport layer 21 include 4,4 ′, 4 ″ -tris (N- (2-naphthyl) -N-phenylamino) triphenylamine and the like. Various conventionally known aromatic amine derivatives such as a triphenylamine derivative (TPD) can be used.Before forming the hole transport layer 21, copper phthalocyanine (CuPC) or the like can be used as a hole injection layer (see FIG. (Not shown).
[0061]
Next, after positioning the second shadow mask 7 having an opening capable of depositing every third ITO electrode 20b with respect to the first shadow mask 6, the second shadow mask 7 is moved to the first shadow mask 6 side. , And are arranged while maintaining a predetermined distance (step S7). At this time, the positional relationship between the ITO substrate 20 on which the hole transport layer 21 is formed and the first and second shadow masks 6 and 7 is in the initial state shown in FIG.
[0062]
Here, a second shadow mask 7 made of a Ni—Fe alloy and having a thickness of 100 μm is used. The dimensions of the opening are 110 μm on the short side, 330 μm on the long side, 350 μm between the short sides of the adjacent opening, and 30 μm between the long sides of the adjacent opening. The distance between the first and second shadow masks 6 and 7 is 500 μm.
[0063]
In the initial state shown in FIG. 8A, a predetermined luminescent material is deposited on the hole transport layer 21 by a vacuum deposition method to form a red luminescent layer 22 (Step S8).
Thereafter, as shown in FIG. 8B, the first shadow mask 6 is not moved, but only the second shadow mask 7 is moved in parallel by 120 μm (step S9), and vacuum deposition is performed on the hole transport layer 21. The green light emitting layer 23 is formed by the method (Step S10).
[0064]
Similarly, as shown in FIG. 8C, only the second shadow mask 7 is further translated by 120 μm (step S11), and a blue light emitting layer 24 is formed on the hole transport layer 21 by a vacuum evaporation method (step S11). Step S12).
[0065]
As the light emitting material used for forming each light emitting layer in steps S8, S10, and S12, for example, a tris (8-quinolite) aluminum complex (Alq ₃ ), A mixture of about 0.5% to 10% of a naphthalene derivative or a pyrene derivative depending on the emission color can be used. In addition, as the light-emitting material, a conventionally known organic metal material or organic material such as bis (benzoquinolinolato) beryllium complex (BeBq) or poly (p-phenylenevinylene) can be used.
[0066]
The light emitting layer is usually formed with a thickness of about 10 nm to 500 nm, preferably about 10 nm to 100 nm. If the thickness is less than 10 nm, the efficiency of recombination of holes and electrons in the layer may decrease, while if it exceeds 500 nm, the driving voltage may increase.
[0067]
Subsequent to the formation of each light emitting layer, an electron transport layer (not shown) is formed (Step S13). The electron transport layer is usually formed with a thickness of about 10 nm to 500 nm, preferably about 20 nm to 100 nm. The range of the film thickness is defined for the same reason as in the case of the hole transport layer 21.
[0068]
This electron transport layer is formed by moving the second shadow mask 7 and retreating it from between the first shadow mask 6 and the evaporation source 5 and then evaporating the electron transport layer material by vacuum evaporation. Do. As an electron transport layer material, Alq ₃ Conventionally known organic metal materials and organic materials such as 1,2,4-triazole derivative (TAZ) can be used in addition to and metal oxide and baxoproin (BCP).
[0069]
Next, a cathode (not shown) is formed on the electron transport layer by a vacuum evaporation method (Step S14). The cathode is usually formed with a thickness of 20 nm or more. In particular, the thickness is preferably about 50 to 200 nm in consideration of the effect of increasing the conductivity by increasing the thickness of the cathode and the time required for forming the cathode. As the cathode material, a conventionally known material such as an Al—Li alloy or an Al—Mg alloy can be used in addition to LiF / Al including an electron injection layer.
[0070]
Finally, an insulating sealing film (not shown) is formed (Step S15), and the formation of the organic EL element is completed.
The organic thin film of the organic EL element thus formed has a uniform thickness in each pixel, and is formed by a single shadow mask having an opening like the second shadow mask 7 as in the related art. Compared to the case of forming, the distribution of the film thickness in the pixel can be formed within ± 3%.
[0071]
Further, the distribution of luminance in the pixels of the organic EL display panel formed up to the cathode and the sealing film was extremely good, and no luminance unevenness was observed.
In addition, the pixels of the organic EL display panel 30 days after manufacture have the same light emitting area as the pixels when the organic EL element is formed, and the conventional organic EL display panel has a non-light emitting area near the partition. In some cases, good results were obtained.
[0072]
In the above-described formation example, the hole transport layer 21 is formed after the first shadow mask 6 is disposed in contact with the ITO electrode 20b, but the hole transport layer 21 is formed by the first shadow mask 6 May be formed on the entire surface of the ITO substrate 20 before the arrangement.
[0073]
FIG. 9 is a view for explaining an organic thin film forming step in the case where the hole transport layer is formed on the entire surface of the ITO substrate. However, in FIG. 9, the same elements as those in the configuration shown in FIG. 8 are denoted by the same reference numerals, and detailed description thereof will be omitted.
[0074]
In this case, after the hole transport layer 21 is formed on the entire surface of the ITO substrate 20, that is, on the soda glass 20a and the ITO electrode 20b, the ITO substrate 20 and the first shadow mask 6 are positioned. Then, the first shadow mask 6 is moved to the ITO substrate 20 side, and is brought close to the hole transport layer 21. At that time, the first shadow mask 6 can be arranged so as to be in contact with the hole transport layer 21. That is, in the case where the hole transport layer 21 is formed on the entire surface of the ITO substrate 20 as described above, the ITO substrate 20 on which the hole transport layer 21 is formed is replaced with a substrate such as the substrate 2 shown in FIG. Should be considered.
[0075]
Thereafter, the second shadow mask 7 is positioned and arranged with a distance of 500 μm from the first shadow mask 6 to form the red light-emitting layer 22 as in the above-described example. The green light-emitting layer, the blue light-emitting layer, the electron transport layer, the cathode, and the sealing film may be formed as shown in the above-described formation examples.
[0076]
Since the hole transport layer 21 is formed on the entire surface of the ITO substrate 20 as described above, the hole transport layer 21 is interposed between the ITO electrode 20b and the cathode. Shorts can be reliably prevented. Therefore, the cathode can be formed in a stripe shape so as to intersect with the ITO electrode 20b.
[0077]
Note that, in the above formation examples, the order of forming the light emitting layers is not limited to the order of the red light emitting layer, the green light emitting layer, and the blue light emitting layer. Further, the principle is the same even when all or a part of the light emitting layer has a structure which functions as both a carrier transporting layer and a light emitting layer, such as a hole transporting light emitting layer or an electron transporting light emitting layer. Further, the principle is the same even when the hole injection layer or the electron injection layer mentioned in the above example is added as a component of the organic EL element. That is, the first shadow mask 6 may be fixed, and the second shadow mask 7 may be appropriately moved to form each layer such as a predetermined light emitting layer in a predetermined region.
[0078]
Further, in the above description, the formation of an organic thin film obtained by evaporating an organic material or an organic metal material has been described as an example, but the thin film forming apparatus of the present invention is generally used for forming an organic thin film and a metal thin film. The present invention can be applied to formation of a thin film that can be formed by a vacuum evaporation method.
[0079]
(Supplementary Note 1) In a thin film forming apparatus, a vapor deposition material is heated and vaporized by a vapor deposition source, and the vaporized vapor deposition material is deposited on an object to form a thin film.
A first shadow mask having an opening group formed so that the deposition material is deposited on a region where the thin film is to be formed on the workpiece;
A second shadow mask having an opening formed so that the deposition material reaches a part of the opening group;
A thin film forming apparatus comprising:
[0080]
(Supplementary Note 2) The thin film forming apparatus according to Supplementary Note 1, wherein the first shadow mask is arranged in proximity to or in contact with the object.
(Supplementary Note 3) The thin film forming apparatus according to Supplementary Note 1, wherein the second shadow mask is arranged to be separated from the first shadow mask by a predetermined distance.
[0081]
(Supplementary Note 4) When depositing another deposition material on another part other than the part of the opening group, the second shadow mask allows the other deposition material to reach the other part. The thin film forming apparatus according to claim 1, wherein the opening is moved to a position corresponding to the other part.
[0082]
(Supplementary Note 5) A positioning mechanism for appropriately setting a position of the first shadow mask with respect to the workpiece and a position of the second shadow mask with respect to the first shadow mask. 2. The thin film forming apparatus according to claim 1, wherein
[0083]
(Supplementary Note 6) The opening of the first shadow mask is a rectangle having dimensions X1 and Y1. The thin film forming apparatus according to claim 1, wherein when Y2, the opening dimensions X3 and Y3 of the second shadow mask satisfy X1 ≦ X3 <X1 + X2 and Y1 ≦ Y3 <Y1 + Y2.
[0084]
(Supplementary Note 7) The opening of the first shadow mask is a rectangle having dimensions X1 and Y1, and the distance between the openings adjacent to each other in the X1 dimension is X2, and the distance between the openings adjacent to the Y1 dimension is When Y2 and the number of openings arranged in the Y1 dimension direction are n, the opening sizes X3 and Y3 of the second shadow mask satisfy Y1 ≦ Y3 <n (Y1 + Y2) −Y2. 3. The thin film forming apparatus according to claim 1, wherein
[0085]
(Supplementary Note 8) In a thin film forming method, a vapor deposition material is heated and vaporized by a vapor deposition source, and the vaporized vapor deposition material is deposited on an object to form a thin film.
Disposing a first shadow mask having an opening group formed so that the deposition material is deposited on a region where the thin film is to be formed on the workpiece, on the deposition source side of the workpiece. When,
Arranging a second shadow mask having an opening formed so that the evaporation material reaches a part of the opening group on the side of the evaporation source with respect to the first shadow mask;
A step of heating and vaporizing the vapor deposition material at the vapor deposition source, forming the thin film by depositing the vaporized vapor deposition material on the workpiece in the part;
A method of forming a thin film, comprising:
[0086]
(Supplementary Note 9) The first shadow mask having the opening group formed so that the deposition material is deposited on a region where the thin film is to be formed on the workpiece is formed by the deposition of the workpiece. 9. The thin film forming method according to claim 8, wherein in the step of arranging the first shadow mask on the source side, the first shadow mask is arranged close to or in contact with the object.
[0087]
(Supplementary Note 10) The second shadow mask having the opening formed so that the deposition material reaches a part of the opening group may be located closer to the deposition source than the first shadow mask. 9. The thin film forming method according to claim 8, wherein, in the disposing step, the second shadow mask is disposed at a predetermined distance from the first shadow mask.
[0088]
(Supplementary Note 11) After the step of heating and vaporizing the vapor deposition material with the vapor deposition source and depositing the vaporized vapor deposition material on the object to be formed in the part to form the thin film, When depositing another deposition material on another part other than the one part, the second shadow mask is moved to the other opening so that the other deposition material reaches the other part. 9. The thin film forming method according to claim 8, further comprising a step of moving to a position corresponding to the portion and forming another thin film on the object to be formed in the other part.
[0089]
【The invention's effect】
As described above, in the present invention, a thin film forming apparatus includes a first shadow mask having an opening group formed so that a deposition material is deposited on a region where a thin film is to be formed on an object, and a first shadow mask having the same. A structure including a second shadow mask having an opening formed so that a deposition material reaches a part of the opening group is adopted. Thus, a thin film can be formed in a desired region on the object with high accuracy and high uniformity.
[0090]
In particular, since the organic thin film can be formed with high accuracy and uniform thickness, a high-performance organic EL display panel can be realized at low cost.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration example of a thin film forming apparatus.
FIG. 2 is a schematic plan view of a first shadow mask.
FIGS. 3A and 3B are schematic plan views of a second shadow mask, each showing (a) a case where each opening is arranged independently, and (b) a case where each opening is arranged in a slit shape. Is shown.
FIG. 4 is a view showing an opening of a first shadow mask.
FIG. 5 is an explanatory diagram of a method for positioning a substrate and first and second shadow masks.
FIGS. 6A and 6B are schematic side views of the substrate and the first and second shadow masks when an organic thin film is formed, respectively showing (a) an initial state and (b) a state after moving the second shadow mask. .
FIG. 7 is a diagram showing an example of a flow of forming an organic EL element.
FIG. 8 is a view for explaining a light emitting layer forming step, in which (a) a red light emitting layer forming step, (b) a green light emitting layer forming step, and (c) a blue light emitting layer forming step.
FIG. 9 is a diagram illustrating an organic thin film forming step when a hole transport layer is formed on the entire surface of an ITO substrate.
FIG. 10 is a diagram showing an example of the arrangement of pixels of an organic EL display panel.
[Explanation of symbols]
1 Thin film forming equipment
2 Substrate
2a, 20a ITO electrode
3 Deposition chamber
4 Exhaust mechanism
5 evaporation source
6 First shadow mask
7 Second shadow mask
8 Mask moving mechanism
9 Positioning mechanism
10 control unit
11,12 Alignment mark
13,14 Organic thin film
20 ITO substrate
20a Soda glass
21 Hole transport layer
22 Red light emitting layer
23 green light emitting layer
24 blue light emitting layer
60a, 60b, 60c, 70a Opening
X1, Y1 dimensions
X2, Y2 interval
X3, Y3 opening dimensions

Claims (5)

In a thin film forming apparatus that heats and vaporizes a vapor deposition material with a vapor deposition source and deposits the vaporized vapor deposition material on an object to form a thin film,
A first shadow mask having an opening group formed so that the deposition material is deposited on a region where the thin film is to be formed on the workpiece;
A second shadow mask having an opening formed so that the deposition material reaches a part of the opening group;
A thin film forming apparatus comprising: 2. The thin-film forming apparatus according to claim 1, wherein the first shadow mask is arranged close to or in contact with the object. 2. The thin film forming apparatus according to claim 1, wherein said second shadow mask is arranged at a predetermined distance from said first shadow mask. When depositing another deposition material on another part other than the one part of the opening group, the second shadow mask is arranged so that the other deposition material reaches the other part. 2. The thin film forming apparatus according to claim 1, wherein the apparatus is moved to a position corresponding to the other part. In a thin film forming method for forming a thin film by heating and vaporizing a vapor deposition material at a vapor deposition source and depositing the vaporized vapor deposition material on an object to be formed,
Disposing a first shadow mask having an opening group formed so that the deposition material is deposited on a region where the thin film is to be formed on the workpiece, on the deposition source side of the workpiece. When,
Arranging a second shadow mask having an opening formed so that the evaporation material reaches a part of the opening group on the side of the evaporation source with respect to the first shadow mask;
A step of heating and vaporizing the vapor deposition material at the vapor deposition source, forming the thin film by depositing the vaporized vapor deposition material on the workpiece in the part;
A method of forming a thin film, comprising:

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