JPH10298738A - Shadow mask and vapor depositing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the width and the deviation of the position of a vapor depositing pattern and to form vapor deposited film on a substrate with high precision, by inclining the inner circumferential wall faces of plural openings provided on a shadow mask arranged between the substrate and a vapor depositing source in a direction in which the slit width expands as it goes to the vapor depositing source side. SOLUTION: A shadow mask 1 has a shape, in which the slit inner circumferential wall faces of both side parts in the longitudinal direction of a slit 1A project into a cross-sectional elliptic arc shape. The side of the vapor depositing source than the intermediate part between the planer face on the side of the substrate 11 and the planar face on the side of the vapor depositing source in the shadow mask 1 has an inclined curved face in which the slit width is made wider as it goes to the vapor depositing source side. The substrate side has an inclined curved face in which the slit width is made wider as it goes to the substrate side than the intermediate part. By using this shadow mask 1, vapor deposited coating with the width approximately same as that of the slit 1A can be formed. By this shadow mask 1, the further refining and the improvement of the precision of and element can be attained, and moreover, elements having different light emitting characteristics per dot can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask and a vapor deposition method, and more particularly, to a method for forming an organic hole transport layer, an organic light emitting layer, an anode or a cathode of an organic electroluminescent device by a vacuum deposition method. The present invention relates to a shadow mask and a vapor deposition method suitable for the present invention.

[0002]

2. Description of the Related Art Organic electroluminescent devices have attracted attention as new flat-type light emitting sources and display devices having characteristics such as self-emission, thinness, and a wide viewing angle.

FIGS. 6 to 8 are cross-sectional views schematically showing examples of the structure of a general organic electroluminescent device.
Is an anode, 13 is an organic light emitting layer, 13a is a hole transport layer, 13
b represents an electron transport layer, 13a 'represents an anode buffer layer, and 14 represents a cathode. The general materials and configurations described below are described in detail in JP-A-8-236271.

[0004] The substrate 11 serves as a support for the organic electroluminescent device, and is made of a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet, or the like.

[0005] An anode 12 is provided on a substrate 11.
The anode 12 plays a role of injecting holes into the organic light emitting layer 13. This anode 12 is usually made of aluminum,
Metals such as gold, silver, nickel, palladium and platinum; metal oxides such as oxides of indium and / or tin; metal halides such as copper iodide; carbon black; or poly (3-methylthiophene); It is made of a conductive polymer such as polypyrrole and polyaniline. Anode 12
Is usually formed by a sputtering method, a vacuum evaporation method or the like in many cases.

An organic light-emitting layer 13 is provided on the anode 12, and the organic light-emitting layer 13 efficiently transfers holes injected from the anode 12 and electrons injected from the cathode between electrodes to which an electric field is applied. It is formed of a material that is well transported and recombined, and emits light efficiently by recombination. Usually, in order to improve the luminous efficiency, the organic light emitting layer 13 is divided into a hole transport layer 13a and an electron transport layer 13b to be of a function separation type as shown in FIG. 7 (Appl. Phys. . Let
t., 51, 913, 1987).

In the above-mentioned function-separated element, the conditions required for the material of the hole transport layer 13a are that the hole injection efficiency from the anode 12 is high and that the injected holes are transported efficiently. It must be a material that can be used.

The hole transport layer 13a is formed by laminating the above hole transport material on the anode 12 by a coating method or a vacuum evaporation method. The thickness of the hole transport layer 13a is usually 10 to 300 nm, preferably 30 to 100 nm. In order to uniformly form such a thin film, generally, a vacuum deposition method is often used.

In order to improve the contact between the anode 12 and the hole transport layer 13a, it is conceivable to provide an anode buffer layer 13a 'between the anode 12 and the hole transport layer 13a as shown in FIG. The conditions required for the material used for the anode buffer layer 13a 'are as follows: good contact with the anode 12, a uniform thin film can be formed, and the film is thermally stable, that is, the melting point and the glass transition temperature are high, and the melting point is 30.
0 ° C. or higher and a glass transition temperature of 100 ° C. or higher are required.

In the case of the anode buffer layer 13a ', a thin film can be formed in the same manner as the hole transport layer 13a, but in the case of an inorganic substance, a sputtering method, an electron beam evaporation method,
The plasma CVD method is used.

The thickness of the anode buffer layer 13a 'formed as described above is usually 3 to 100 nm, preferably 10 to 50 nm.

The electron transport layer 13 is provided on the hole transport layer 13a.
b is provided. The electron transport layer 13b is formed of a compound capable of efficiently transporting electrons from the cathode between the electrodes to which an electric field is applied in the direction of the hole transport layer 13a.

The electron transporting compound used in the electron transporting layer 13b has a high electron injection efficiency from the cathode 14,
In addition, the compound must be able to efficiently transport the injected electrons. For this purpose, it is required that the compound has a high electron affinity, a high electron mobility, a high stability, and an impurity which becomes a trap and hardly occurs during production or use.

The thickness of the electron transport layer 13b is usually 10 to
It is 200 nm, preferably 30-100 nm.

The electron transporting layer 13b can be formed by the same method as the hole transporting layer 13a, but usually, a vacuum deposition method is used.

The cathode 14 plays a role of injecting electrons into the organic light emitting layer 13. The material used for the cathode 14 is
The material used for the anode 2 can be used, but for efficient electron injection, a metal having a low work function is preferable, and a suitable metal such as tin, magnesium, indium, calcium, aluminum, or silver is used. Alternatively, their alloys are used. The thickness of the cathode 14 is usually the same as that of the anode 2. For the purpose of protecting the cathode made of a low work function metal, it is preferable to further laminate a metal layer having a high work function and being stable to the atmosphere in order to increase the stability of the device. For this purpose, metals such as aluminum, silver, nickel, chromium, gold, platinum and the like are used.

It is to be noted that the structure opposite to that of FIG. 6, that is, the cathode 14, the organic light emitting layer 13, and the anode 12 can be laminated on the substrate in this order, and at least one of them has high transparency as described above. An organic electroluminescent element can be provided between two substrates. Similarly, the layers shown in FIGS. 7 and 8 can be stacked in an inverted structure.

Conventionally, in general, such an organic electroluminescent device is generally formed by first forming a transparent conductive film such as ITO (indium tin oxide) on a glass substrate by sputtering or the like, and then pattern-processing the lower electrode. The substrate is placed in a vacuum evaporation tank, and an organic light emitting layer and an upper electrode are formed by a method such as heating evaporation. In this case, as a method of separating the luminescent pixels, a method of forming a partition for pixel separation on a substrate in advance before vapor deposition (Japanese Patent Laid-Open No. 5-2 / 1993).
No. 58859, JP-A-8-315961)
Also, a method of performing ablation processing with a laser after vapor deposition (Japanese Patent Application Laid-Open No. 8-222371) and a method of using a general shadow mask having a large pattern size at the time of vapor deposition are performed.

Hereinafter, a method of manufacturing a plurality of luminescent pixels on the same substrate by a vacuum deposition method using a shadow mask will be described with reference to FIGS.

First, the anode layer deposited on the substrate 11 is subjected to pattern processing, and as shown in FIG. 9, linear anodes 12 parallel to each other are manufactured. As a method of patterning the anode layer, there is a method in which an organic resist is patterned using a generally used photolithography method, and then the exposed anode is etched and removed with an acidic aqueous solution or the like. Other examples of the etching method include a plasma etching method using oxygen and argon gas, a focused ion beam (FIB) method, and the like.

Next, as shown in FIG. 10, at least each of the organic layers 13, 13a and 13b, or 13a 'and 13a and 13b and the cathode 14 is formed using a shadow mask 20 having a plurality of slits 20A parallel to each other. One layer is formed by vacuum evaporation. For example, all of the organic layer and the cathode 14 are formed by vapor deposition using the shadow mask 20, or the cathode 14 is vapor deposited using the shadow mask 20 after the organic layer is vapor deposited. In this case, in the shadow mask 20, the extension direction of the slit 20A is the anode 1
2 are arranged so as to be orthogonal to the extending direction. Thus, for example, by forming the cathode 14 using the shadow mask 20, the anode 12 and the cathode 14 are orthogonal to each other as shown in FIG. The organic electroluminescent device having the layer structure shown in FIG. 1 is formed (in FIG. 11, the organic layer between the anode 12 and the cathode 14 is not shown).

[0022]

Among the above-mentioned conventional methods of separating luminescent pixels, the method of forming a partition for pixel separation on a substrate before vapor deposition requires an increased number of processing steps and a pattern formation. Problems have been pointed out, such as a decrease in yield due to defects, and deterioration of device characteristics due to the partition walls remaining inside the sealed device. Further, the method of performing ablation processing by laser after vapor deposition also has a problem that the number of processing steps increases and the processing cost increases. In addition, when a general method of using a shadow mask at the time of vapor deposition is used, it is difficult to form a line and space pattern of 300 μm or less due to the problem of rigidity of the shadow mask, or when vapor deposition is performed using a shadow mask having a narrow space. In addition, there have been problems such that the edge of the space portion of the mask becomes a shadow and uniform deposition cannot be performed on the substrate, or the pattern is shifted.

Hereinafter, problems in a conventional vapor deposition method using a shadow mask will be described with reference to FIGS. In the following description, it is assumed that the deposition material that has passed through the slit of the shadow mask travels straight to the substrate, and the amount of inward wraparound is assumed to be extremely small and is ignored.

FIG. 12 shows a deposited film using a shadow mask,
For example, the substrate 11 and the shadow mask 20 set on the substrate holder 32 in the vacuum deposition tank 31 when forming the cathode
FIG. 2 is a cross-sectional view schematically showing the arrangement of a deposition cell 30. FIG. 12 also schematically shows a state of the vapor deposition material heated and scattered from the vapor deposition cell 30. Of the scattered deposition materials 30A, those that have passed through the slits 20A of the shadow mask 20 are deposited on the substrate 11 to form a deposition film. At this time, it is desired that the deposition material be deposited on the substrate 11 while reproducing the shape of the slit 20A of the shadow mask 20 as faithfully as possible.

FIG. 13 shows the substrate 11 and the shadow mask 20.
FIG. 14 is a diagram showing parameters for explaining the arrangement of the deposition cell 30 and the shape or position where the deposition material 30A is deposited on the substrate 11, and FIG. 14 is an enlarged view of a main part of FIG.
The center line L indicates the direction connecting the center of the substrate 11 and the center of the vapor deposition cell 30. r is the distance from the center of the shadow mask (center line L) to the inner wall surface 20a of the outermost slit 20A of the outermost slit 20A of the shadow mask 20, t is the thickness of the shadow mask, and g is the distance from the surface of the substrate 11 during vapor deposition. The distance h between the shadow mask 20 and the surface on the substrate 11 side indicates the distance between the substrate 11 and the vapor deposition cell 30.

Further, it s is the outermost slit 20A of the width of the shadow mask 20, a ₀ is the deposition material 30A that has passed through the inside of the vicinity of the inner peripheral wall surface 20a slits of the slit 20A
Is the distance between the position at which the substrate 11 reaches the substrate 11 and the perpendicular foot lowered onto the substrate 11 from the slit inner peripheral wall surface 20a, and b ₀ is the substrate on which the deposition material 30A passing near the slit inner peripheral wall surface 20b outside the slit 20A is placed. 11 shows the distance between the position where the substrate 11 reaches the position 11 and the perpendicular foot lowered from the inner wall surface 20b of the slit to the substrate 11. That is, a ₀ indicates the shift amount inside the deposition position, and b ₀ indicates the shift amount outside the deposition position. Therefore, b ₀ −
a ₀ (hereinafter, referred to as “Δw”) indicates the amount of increase or decrease of the width of the vapor deposition pattern with respect to the width s of the slit 20A of the shadow mask 20, and (a ₀ + b ₀ ) / 2 (hereinafter, referred to as “Δ
D ". ) Is the slit 20A of the shadow mask 20
And the average shift amount of the vapor deposition pattern in the horizontal direction.

The amount of increase / decrease Δw of the width of the vapor deposition pattern and the amount of positional deviation ΔD are determined by the thickness t of the shadow mask 20,
1 indicates a distance g between the shadow mask 20, a distance h between the substrate 11 and the vapor deposition cell 30, and r indicates a distance from the center of the vapor deposition surface.
Is dependent on the amount.

For example, in the case of a generally used evaporation method, the following values are used for t, g, h, and r.

T = 0.2 mm g = 0.01 mm h = 400 mm r = 100 mm Under such deposition conditions, the conventional shadow mask 2
In vapor deposition using 0, the increase / decrease amount Δw of the width of the vapor deposition pattern and the positional deviation amount ΔD are obtained by calculation as follows.

Δw = 0.05 mm ΔD = 0.0275 mm The values of Δw and ΔD are such that the width s of the outermost slit 20 A of the shadow mask 20 is sufficiently smaller than the distance r from the center of the mask. This is a value obtained by approximation and calculation.

By the way, the increase / decrease amount Δw of the width of the vapor deposition pattern
The above calculation results indicate that the stripe width of the vapor deposition film deposited through the shadow mask 20 cannot be reduced to 0.05 mm or less.
This indicates that it is not practical to form a deposited film having a stripe width of 0.5 mm, which is about%.

On the other hand, the stripe width of one pixel of a display of a general mobile terminal or personal computer at present is about 0.3 mm for monochrome display and about 0.1 mm for color display. With such a value, a vapor deposition film suitable for such a display cannot be obtained.

In general, the width s of the slit 20A of the shadow mask 20 used for vapor deposition is substantially equal to the thickness t of the shadow mask 20, but when the interval between the adjacent slits 20A becomes narrow, the shadow mask 20 is mechanically moved. There is also a problem that it is difficult to maintain the strength independently. For example, 0.3 mm pitch (stripe width 0.3 m
In the case of fabricating the device of m), considering that the device is separated with a width of 10% of the pitch, the slit interval (20B in FIG. 10) is 0.1 mm for the slit width s = 0.3 mm of the shadow mask 20. 03 mm. In this case, 0.1 mm
It is difficult to hold the stripe with the shadow mask having the above thickness.

The present invention solves the above-mentioned conventional problems, and provides a shadow mask capable of forming a vapor-deposited film on a substrate with a small deviation in the width and position of a vapor-deposition pattern, and
An object of the present invention is to provide a vapor deposition method capable of forming a fine vapor deposition pattern without impairing the mechanical strength of a shadow mask.

It is an object of the present invention to form a fine organic electroluminescent element with high precision by using such a shadow mask and a vapor deposition method.

[0036]

According to a first aspect of the present invention, there is provided a shadow mask for vapor deposition processing disposed along a substrate between a substrate and a vapor deposition source, wherein the shadow mask has a plurality of openings. In the above shadow mask, at least the deposition source side of the inner peripheral wall surface of the opening is inclined with respect to the shadow mask plate surface in a direction in which the slit width increases toward the deposition source side.

With such a shadow mask, the flow rate of the deposition material is cut off at the edge of the inner peripheral wall surface of the opening of the shadow mask. Thus, a deposited film can be formed with high precision following the shape of the opening of the shadow mask.

The inner peripheral wall surface of the opening of the shadow mask may be inclined from the substrate side of the shadow mask to the evaporation source side, and may be an intermediate surface between the substrate surface of the shadow mask and the plate surface of the evaporation source side. Only the evaporation source side may be inclined with respect to the shadow mask plate surface, and the substrate side may be perpendicular to the shadow mask plate surface. The evaporation source side has an inclined surface with a larger slit width toward the evaporation source side than an intermediate portion with the source side plate surface, and the substrate side than the intermediate portion has an inclined surface with a larger slit width as the substrate side. It may be something that has become.

It is preferable that the opening of the shadow mask is symmetrical with respect to the center line of the opening.

Further, when the opening width of the shadow mask on the shadow mask surface on the side of the vapor deposition source is s ₁ , the smallest opening width of the opening is s _2, and the thickness of the shadow mask is t, Ratio of (s ₁ −s ₂ ) and t (s ₁ −s ₂ ) /
Preferably, t is from 0.2 to 20.

The vapor deposition method according to claim 7 is characterized in that such a shadow mask is arranged between the substrate and the vapor deposition source along the substrate and vapor deposition is performed to form a vapor deposited film on the substrate.

In a vapor deposition method according to the present invention, a shadow mask having a plurality of apertures is disposed between a substrate and a vapor deposition source along the substrate to perform vapor deposition processing, and a shadow mask corresponding to the apertures is formed on the substrate. In the vapor deposition method of forming a vapor deposition film, after forming the vapor deposition film, the shadow mask is vapor-deposited by changing the position in the arrangement direction of the openings, and a vapor deposition film is formed between the vapor deposition films already formed. It is characterized by the following.

According to this method, it is possible to form a vapor-deposited film having a narrow distance between adjacent vapor-deposited films by using a shadow mask having a large distance between adjacent holes. Therefore, a fine vapor deposition pattern can be formed while securing the mechanical strength of the shadow mask.

In the above method, it is preferable to use the shadow mask according to the present invention as the shadow mask.

The method of the present invention is particularly suitable as a method for forming an organic hole transport layer, an organic light emitting layer, an anode or a cathode of an organic electroluminescent device by a vapor deposition process.

[0046]

Embodiments of the present invention will be described below in detail.

First, a vapor deposition method using the shadow mask of the present invention will be described with reference to FIGS. In FIGS. 1 and 2, reference numeral 11 denotes a substrate, and reference numeral 30A denotes an evaporation substance scattered from an evaporation cell.

FIG. 1 is a schematic cross-sectional view showing a vapor deposition method when the shadow mask 1 of the present invention is used in place of the conventional shadow mask 20 in FIG. 14 (in the direction perpendicular to the longitudinal direction of the slit of the shadow mask). FIG.

In the shadow mask 1 shown in FIG. 1, the inner peripheral wall surfaces of the slits on both sides in the longitudinal direction of the slit 1A have a shape protruding in an elliptical arc shape in cross section. The evaporation source side has an inclined curved surface in which the slit width is larger on the evaporation source side than the middle part between the plate surface and the plate surface on the evaporation source side, and the slit side is larger on the substrate side than the middle part on the substrate side. It becomes the inclined curved surface.

Both sides in the longitudinal direction of the slit 1A are symmetrical with respect to a center line extending in the longitudinal direction of the slit.

In order to manufacture such a shadow mask 1, first, a metal plate serving as a mask material is prepared, and a resist pattern is formed on both surfaces of the plate. At this time, it is necessary that the positions of the resist patterns on both sides are exactly the same on the front and back sides. Next, the metal plate is immersed in an acidic aqueous solution or the like capable of etching the metal material, and is gradually etched from a portion not protected by the resist. At this time, by arbitrarily selecting the solution concentration and the stirring intensity of the solution during the etching, it is possible to set the etching tendency of this system to an arbitrary tendency between the reaction rate control and the diffusion rate control. In the case of the shadow mask 1, the thickness t of the mask
The etching tendency is set so that the same degree of under-etching occurs, and the etching is completed when the interval between the central convex portions in the thickness direction of the mask becomes a desired slit width s ₂ , thereby producing the mask. . The term “under-etching” as used herein refers to a phenomenon in which a metal portion protected by a resist is gradually exposed to an etching solution from the side and is etched by the progress of etching of an unprotected metal portion.

[0052] For the case in which evaporation is performed using such a shadow mask 1, as in the calculation method of FIG. 14 described above, the inside of the shift amount a ₁ of the deposition positions of the deposition pattern from the outside of the displacement amount b ₁ Width change Δw = b ₁ -a ₁
When the average deviation ΔD = (a ₁ + b ₁ ) / 2 in the horizontal direction is calculated, Δw = 0 mm ΔD = 0.0275 mm From Δw = 0, it can be seen that the use of the shadow mask 1 makes it possible to produce a deposition film having substantially the same width as the slit 1A of the shadow mask 1. Further, ΔD is equivalent to the case where the conventional shadow mask 20 is used, and it can be seen that a desired pattern can be obtained by correcting the shift amount in the shadow mask manufacturing stage.

FIG. 2 is a schematic cross-sectional view showing a vapor deposition method when the shadow mask 2 of the present invention is used in place of the conventional shadow mask 20 in FIG. 14 (in the direction perpendicular to the longitudinal direction of the slit of the shadow mask). FIG.

In the shadow mask 2 shown in FIG. 2, the cross-sectional shape of the slit 2A in a direction orthogonal to the longitudinal direction of the slit 2A is trapezoidal. The shadow mask 2 has a structure that is inclined with respect to the surface of the shadow mask plate in a direction in which the slit width increases from the substrate side to the evaporation source side toward the evaporation source side.

Both sides in the longitudinal direction of the slit 2A are symmetrical with respect to a center line extending in the longitudinal direction of the slit.

To manufacture such a shadow mask 2, first, a metal plate serving as a mask material is prepared, one surface of the plate is entirely covered with a resist, and a resist pattern is formed on the other surface. Next, this metal plate is immersed in an acidic aqueous solution, and is gradually etched from a portion not protected by the resist. At this time, the tendency of the etching of this system can be selected in the same manner as in the case of manufacturing the shadow mask 1.
If the shadow mask 2, ends the etching where set trends etched to undercut comparable to the thickness t of the mask occurs, the side of the slit width was entirely protected by the resist becomes desired width s ₂ Can be manufactured.

[0057] For the case in which evaporation is performed using such a shadow mask 2, in the same manner as the calculation method in FIG. 14 described above, the inside of the shift amount a ₂ deposition position, outside of the shift amount b ₂ of the deposition pattern Width change Δw = b ₂ −a ₂
When the average deviation amount ΔD = (a ₂ + b ₂ ) / 2 in the horizontal direction is calculated, Δw = 0 mm ΔD = 0.0025 mm From Δw = 0, it can be seen that the use of the shadow mask 2 makes it possible to produce a deposition film having substantially the same width as the slit 2A of the shadow mask 2, as in the case of using the shadow mask 1. Further, ΔD is as small as about 1/10 of the case where the conventional shadow mask 20 or the shadow mask 1 of FIG. 1 is used, and it can be seen that a deposition film that accurately reproduces the pattern of the shadow mask can be formed.

The shadow mask shown in FIGS. 1 and 2 is an embodiment of the shadow mask of the present invention. In the shadow mask of the present invention, at least the deposition source side of the slit inner peripheral wall on both sides in the longitudinal direction of the slit has the following characteristics. What is necessary is just to incline with respect to the shadow mask plate surface in the direction in which the slit width increases toward the evaporation source side (this inclined surface may be an inclined curved surface or a combination of inclined surfaces or inclined surfaces. However, the present invention is not limited to those shown in FIGS.

For example, as shown in FIG. 3A, of the inner peripheral wall surface of the slit 3A, only the evaporation source side is inclined with respect to an intermediate portion between the plate surface of the shadow mask on the substrate side and the plate surface on the evaporation source side. The shadow mask 3 in which the substrate side of the intermediate portion is perpendicular to the shadow mask plate surface, FIG.
As shown in FIG. 3B, the shadow mask 4 in which the inner peripheral wall surface of the slit 4A is inclined from the substrate side of the shadow mask to the evaporation source side, or as shown in FIG.
By providing a protruding portion having a triangular cross-section on the inner peripheral wall surface of the slit 5A, the slit width becomes closer to the evaporation source side than the intermediate portion between the substrate surface of the shadow mask and the plate surface of the evaporation source side. The shadow mask 5 or the like may have a larger inclined surface, and the substrate side of the intermediate portion may have an inclined surface having a larger slit width toward the substrate side.

In such a shadow mask of the present invention, the slit width in the shadow mask on the vapor deposition source side, that is, the maximum slit width is s _1, and the smallest slit width (minimum slit width) is s ₂ , If the thickness of the t, the ratio of (s ₁ -s ₂₎ and _{t (s 1 -s 2) /} t is preferably from 0.2 to 20. If this ratio is less than 0.2, the effect of the present invention cannot be sufficiently obtained. Further, it is not easy to produce a slit having this ratio exceeding 20. Usually,
(S ₁ −s ₂ ) / t is preferably in the range of 0.4 to 4.

In the normal case, the maximum slit width s ₁ of the shadow mask is a ratio s ₁ to the thickness t of the shadow mask.
/ T is set in the range of 1.2 to 5.

By the way, as described above, conventionally, when the interval between the slits of the shadow mask is reduced, the mechanical strength of the shadow mask is insufficient, and the self-sustainability of the shadow mask is deteriorated. Therefore, it is difficult to form a fine vapor deposition film having a narrow stripe interval in designing a shadow mask.

In the method of the present invention, the shadow mask is provided with a relatively large slit interval, and the shadow mask is moved to perform vapor deposition, whereby a fine vapor deposition film having a narrow stripe interval can be formed.

The vapor deposition method will be described below with reference to FIGS.

FIG. 4 shows a method in which slits 2A are formed in the shadow mask 2 at a ratio of one per three stripes of a desired vapor deposition pattern, and vapor deposition is performed using a shadow mask manufactured by thinning out two stripes. FIG. 4 is a schematic cross-sectional view conceptually showing. In FIG. 4, the shadow mask 2 is moved twice in the direction perpendicular to the longitudinal direction of the slit 2A by the pitch of the stripe of the vapor deposition pattern to be formed, thereby forming vapor deposition patterns of stripes at desired intervals. FIG. 5 shows the temporal relationship between the movement of the shadow mask 2 and the flying of the deposition material at this time.

In FIG. 5, the upper rectangular wave shows the timing of moving and stopping the shadow mask, and the lower rectangular wave shows the opening and closing timing of the shutter of the vapor deposition cell for controlling the flying of the vapor deposition material. That is, after the shutter of the deposition cell is opened while the shadow mask 2 is stationary, a deposition film having a desired thickness is formed at a position corresponding to the slit 2A, the shutter is closed, and then the shadow mask 2 is replaced with the shadow mask 2 '. After the shutter is opened, the shutter is opened and a deposition film is formed at a position corresponding to the slit 2A ', and this operation is repeated once again, at the position of the shadow mask 2 "corresponding to the slit 2A". A deposited film is formed. In this way, a vapor deposition pattern with a desired stripe interval can be obtained by performing a total of three vapor depositions and two movements of the shadow mask.

The number of repetitions of the vapor deposition and the movement of the shadow mask depends on the number of thinning of the slits of the shadow mask. In addition to the number described above, a vapor deposition pattern can be formed by vapor deposition twice or more. It is.

When an organic electroluminescent device as shown in FIGS. 6 to 8 is manufactured by this vapor deposition method, for example, when a shadow mask is moved to form an organic layer, the material of the organic layer is deposited every time vapor deposition is performed. , The characteristics of adjacent elements can be easily changed. By using this method, for example, an element that emits light of each color of red, green, and blue can be easily formed in a fine region.

Further, a more complicated pattern can be formed by changing the opening of the shadow mask from a long linear slit to a dot and moving the shadow mask during deposition in both vertical and horizontal directions. Is also possible.

In the method shown in FIGS. 4 and 5, vapor deposition is performed by using the slit-shaped shadow mask of the present invention shown in FIG. 2, but shown in FIGS. 1 and 3 (a) to 3 (c). It goes without saying that a shadow mask may be used. Further, it can be performed using a conventional shadow mask shown in FIG. 14, but it is preferable to use the shadow mask of the present invention in which the opening width on the side of the vapor deposition source is set large from the viewpoint of vapor deposition accuracy.

The shadow mask and the vapor deposition method of the present invention are particularly applicable to the above-mentioned organic electroluminescent device in which the organic luminescent layer (hole transport layer, electron transport layer, organic buffer layer), anode or cathode is subjected to vacuum deposition. This is extremely effective when formed by:

In this case, the organic electroluminescent device may be any one of a single device, a device having a structure arranged in an array, and a structure in which an anode and a cathode are arranged in an XY matrix.

[0073]

EXAMPLES Next, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the description of the following examples unless it exceeds the gist.

Example 1 An organic electroluminescent device having a layer structure shown in FIG. 8 was produced using a shadow mask having the same shape as the shadow mask 1 shown in FIG.

First, a glass substrate 11 having a thickness of 1.1 m
Indium tin oxide (ITO) transparent conductive film is deposited as an anode on the 7059 glass of Corning Co., Ltd. with a thickness of 120 nm (manufactured by Geomatic, Inc .; electron beam film-formed product; sheet resistance: 20Ω), and a glass with an ITO film is formed. A substrate was obtained.

The ITO transparent conductive film deposited on the glass substrate 11 is formed with eight stripes having a line width of 0.35 mm and a repetition pitch of 0.37 mm by using ordinary photolithography technology and hydrochloric acid etching. And The patterned ITO substrate is cleaned by ultrasonic cleaning with acetone, water cleaning with pure water, and ultrasonic cleaning with isopropyl alcohol, and then dried by nitrogen blowing.
After performing UV / ozone cleaning for 10 minutes, the substrate was set in a vacuum evaporation tank, and 1.1 × 10 ⁻⁶ Torr using a cryopump.
(About 1.5 × 10 ⁻⁴ Pa). On this occasion,
In order to observe the state of deposition of the deposition material 30A that flies obliquely and enters the substrate, the substrate 11 is moved 100 degrees from the deposition center.
mm, and the portion for taking out the positive electrode on the substrate 11 was covered with a metal mask.
The distance between the deposition cell and the substrate holder on the deposition center is 3
It was 99 mm.

Next, copper phthalocyanine (H1) shown below was placed in a molybdenum boat placed in a vacuum evaporation tank.
(The crystal form was β-form) was heated to perform vapor deposition. Degree of vacuum 1.
The deposition was performed at 1 × 10 ⁻⁶ torr (about 1.5 × 10 ⁻⁴ Pa) for 1 minute, and the anode buffer layer 1 having a thickness of 20 nm was formed.
3a 'was obtained.

[0078]

Embedded image

Next, 4,4'-bis [N- (1-naphthyl) -N-phenylamino] bisphenyl (H2) shown below, which was also placed in a ceramic crucible similarly arranged in a vacuum evaporation tank, was used. It was heated on a tantalum wire heater around the crucible and laminated on the anode buffer layer 13a '. At this time, the temperature of the crucible was controlled in the range of 230 to 240 ° C. The degree of vacuum at the time of vapor deposition is 8 × 10 ⁻⁷ Torr (about 1.1 × 1
0 ^-4 Pa), and a 60-nm-thick hole transport layer 13a was formed with a deposition time of 1 minute and 50 seconds.

[0080]

Embedded image

Next, as a material of the electron transport layer 13b having a light emitting function, aluminum 8-hydroxyquinoline complex represented by the following structural formula Al (C ₉ H ₆ NO) ₃ (E1)
Was similarly deposited on the hole transport layer 13a. At this time, the temperature of the crucible was controlled in the range of 310 to 320 ° C. The degree of vacuum during the deposition was 9 × 10 ⁻⁷ Torr (about 1.2 × 10 ⁻⁴ Pa), the deposition time was 2 minutes and 40 seconds, and the thickness of the deposited electron transport layer 13b was 75 nm.

[0082]

Embedded image

The above-described hole injection layer 13a ′ and hole transport layer 1
The substrate temperature when vacuum-depositing 3a and the electron transport layer 13b was kept at room temperature.

Next, using a shadow mask having the same cross-sectional shape as that of the shadow mask 1 shown in FIG. It was placed in front of the substrate on which the layers were deposited. At this time, the shadow mask 1 was arranged such that the longitudinal direction of the slit 1A was perpendicular to the direction of the substrate from the center of deposition. The thickness t of the shadow mask 1 used is 0.2 m
m, the slits 1A number eight, the width s ₁ of the aperture 1A is 0.3 mm, s ₂ is _{0.1mm ((s 1 -s 2)} / t =
1) The repetition pitch (slit interval) is 0.36 mm
It is.

Then, an alloy electrode of magnesium and silver was formed as the cathode 14 to a thickness of 100 nm by a binary simultaneous evaporation method.
Vapor deposition was performed so that Vapor deposition was performed using a molybdenum boat and the degree of vacuum was 1 × 10 ⁻⁵ Torr (about 1.3 × 10 ⁻³ P).
a), the deposition time was 3 minutes and 10 seconds. The atomic ratio of magnesium to silver was 10: 1.2. Further on,
The cathode 14 was completed by laminating aluminum with a thickness of 100 nm on the magnesium-silver alloy film using a molybdenum boat in a vacuum evaporation tank. The degree of vacuum during aluminum deposition is 2.3 × 10 ⁻⁵ Torr (about 3.1 × 1 Torr).
0 ^-3 Pa), and the vapor deposition time was 1 minute and 40 seconds. The substrate temperature at the time of vapor deposition of the two-layered cathode of magnesium / silver alloy and aluminum was kept at room temperature.

Thereafter, the element was taken out of the vacuum evaporation tank,
An organic electroluminescent device of 8 dots × 8 dots was obtained.

These elements were made to emit light by applying a positive DC voltage to the anode 12 and a negative DC voltage to the cathode 14, and the emission pattern was measured. The emission area was a rectangle of 0.094 mm × 0.34 mm per dot. Thus, a light-emitting area substantially equal to the width of the slit 1A of the used shadow mask 1 was obtained.

Next, when the position of the light emitting pattern with respect to the shadow mask was measured, an average of about 0.027
mm. The position of the light emitting pattern with respect to the shadow mask was measured by a relative comparison of the distance from each deposition center.

Example 2 An organic electroluminescent device was manufactured in the same manner as in Example 1 except that a shadow mask having the same sectional shape as that of the shadow mask 2 shown in FIG. 2 was used. The thickness t of the shadow mask 2 used is 0.2 mm, the number of the slits 2A is 8, and the width s _{1 of the} slit 2A is 0.3.
mm and s ₂ are 0.1 mm ((s ₁ −s ₂ ) / t = 1),
The repetition pitch (slit interval) is 0.36 mm.

When the emission pattern of the obtained device was measured, the emission area was 0.096 mm × 0.2 mm per dot.
A light-emitting area of 34 mm was obtained, which was almost equal to the width of the slit 2A of the shadow mask 2 used. Also, when the position of the light emitting pattern with respect to the shadow mask 2 was measured, the position was shifted only about 0.005 mm outward on average.

Example 3 As shown in FIG. 4, an organic electroluminescent device was manufactured in the same manner as in Example 1, except that the shadow mask 2 was moved to perform evaporation. The shadow mask 2 used here has slits 2A opened at a ratio of one for every three elements, the thickness t is 0.2 mm, the number of the slits 2A is eight, and the width s _{1 of the} slit 2A. Is 0.3 mm and s ₂ is 0.
1 mm ((s ₁ −s ₂ ) / t = 1), and the repetition pitch (slit interval) is 0.36 mm.

First, the anode 12 and the organic buffer layer 13a
The shadow mask 2 is arranged on the substrate 11 on which
The hole transport layer 13a to the cathode 14 were vapor-deposited in the same manner as in Example 1. Thereafter, the shutter of the vapor deposition cell was closed and the shadow mask was moved by 0.12 mm. Thereafter, the shutter is opened again, and the holes from the hole transport layer 13a to the cathode 14 are vapor-deposited in the same manner as in Example 1. Thereafter, the shutter of the vapor deposition cell is closed and the shadow mask is set to 0.12 mm.
Just moved. After that, the shutter is opened again and the first embodiment is performed.
The hole transport layer 13a to the cathode 14 were vapor-deposited in the same manner as described above, and all vapor deposition was completed.

When the light emission pattern of the device thus obtained was measured, the light emission area was 0.0% per dot.
It became a rectangle of 95 mm × 0.34 mm, and a light emitting area almost equal to the width of the slit 2A of the shadow mask 2 used was obtained. Also, when the position of the light emitting pattern with respect to the shadow mask 2 was measured, an average of about 0.007
mm.

FIG. 15 shows a photograph when the device manufactured in Example 3 was simultaneously illuminated over 7 dots × 8 dots. In FIG. 15, it can be seen that the longer direction of the rectangular element is the cathode line, and light is emitted uniformly in the direction of the cathode line.

In this method, the same hole transport layer 13a is formed in three depositions using the shadow mask 2.
-The material of the electron transport layer 13b may be used, or different substances may be used. When the evaporation was performed by changing the substance, it was possible to change the light emission characteristics such as color tone without changing the shape of the light emitting element.

Comparative Example 1 Next, for comparison, the shadow mask 20 shown in FIG.
Using a conventional shadow mask with the same cross-sectional shape as
Other conditions were the same as in Example 1 to produce an organic electroluminescent device. The thickness t of this shadow mask 20 is 0.2
mm, the number of slits 20A is 8, the width s of slit 2A
Is 0.100 mm, and the repetition pitch (slit interval) is 0.36 mm.

As a result, when the light emitting pattern of the obtained device was measured, the light emitting area was 0.052 per dot.
It was a rectangle of mm × 0.34 mm, and only a light-emitting area approximately half the width of the slit 20A of the shadow mask 20 used was obtained. Further, when the position of the light emitting pattern with respect to the shadow mask 20 was measured, it was shifted on the outside by about 0.029 mm on average.

Table 1 shows the results of the light emission patterns of Examples 1 to 3 and Comparative Example 1.

[0099]

[Table 1]

From the above results, it can be seen that according to the present invention, accurate deposition can be performed.

[0101]

As described in detail above, according to the shadow masks of the first to sixth aspects and the vapor deposition method of the seventh aspect using the shadow mask, a fine vapor deposition pattern is formed with good shape precision and positional precision. be able to.

According to the vapor deposition method of claims 8 and 9,
A fine vapor deposition pattern can be formed while maintaining the mechanical strength of the shadow mask.

The shadow mask and the vapor deposition method of the present invention
In particular, the organic hole transport layer of the organic electroluminescent element, the organic light emitting layer, is effective when forming the anode or the cathode by a vapor deposition process, further miniaturization and accuracy of the element can be achieved,
Further, it is possible to manufacture an element having different light emission characteristics for each dot.

The shadow mask and the vapor deposition method of the present invention
As a flat panel display (for example, for an OA computer, a portable terminal, a wall-mounted television, etc.), it is particularly useful for realizing an organic light-emitting element applicable as a fine light-emitting element or a full-color display element. It is big.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing an evaporation method when a shadow mask according to an embodiment of the present invention is used.

FIG. 2 is a schematic cross-sectional view showing a vapor deposition method when another shadow mask according to an embodiment of the present invention is used.

FIG. 3 is a schematic sectional view showing another embodiment of the shadow mask of the present invention.

FIG. 4 is a schematic sectional view showing an embodiment of the vapor deposition method of the present invention.

FIG. 5 is a time schedule showing a relationship between movement / stop of a shadow mask and opening / closing of a shutter of a deposition cell in the method shown in FIG. 4;

FIG. 6 is a schematic cross-sectional view illustrating an example of a layer configuration of the organic electroluminescent element.

FIG. 7 is a schematic cross-sectional view showing another example of the layer configuration of the organic electroluminescent element.

FIG. 8 is a schematic cross-sectional view showing another example of the layer configuration of the organic electroluminescent element.

FIG. 9 is a schematic perspective view showing an anode patterned in a line on a substrate.

FIG. 10 is a schematic plan view showing a shadow mask for vapor deposition used for patterning an organic electroluminescent element.

FIG. 11 is a schematic plan view showing a positional relationship between an anode and a cathode of the organic electroluminescent device.

FIG. 12 is a schematic cross-sectional view showing a positional relationship among a substrate, a shadow mask, and a deposition cell when an organic electroluminescent device is manufactured.

FIG. 13 is a schematic cross-sectional view illustrating a positional relationship among a substrate, a shadow mask, and a deposition cell.

FIG. 14 is an enlarged view of a main part of FIG. 14;

FIG. 15 is a photograph showing a light emitting pattern of the organic electroluminescent device manufactured in Example 3.

[Explanation of symbols]

 1,2,3,4,5 shadow mask 1A, 2A, 3A, 4A, 5A slit 11 substrate 12 anode 13 organic light emitting layer 13a hole transport layer 13a 'anode buffer layer 13b electron transport layer 14 cathode 20 shadow mask 20A slit Reference Signs List 30 evaporation cell 30A evaporation material 31 vacuum evaporation tank 32 substrate holder

Claims (10)

[Claims] 1. A shadow mask for vapor deposition disposed along a substrate between a substrate and a vapor deposition source, wherein the shadow mask is a thin plate having a plurality of apertures. A shadow mask characterized in that at least the evaporation source side is inclined with respect to the shadow mask plate surface in a direction in which the opening width increases toward the evaporation source side. 2. The shadow mask according to claim 1, wherein the inner peripheral wall surface of the opening is inclined from a substrate side of the shadow mask to a deposition source side. 3. The inner peripheral wall surface of the opening according to claim 1, wherein only the evaporation source side is inclined relative to an intermediate portion between the plate surface of the shadow mask on the substrate side and the plate surface on the evaporation source side. A shadow mask, characterized in that the substrate side of the intermediate portion is perpendicular to the surface of the shadow mask plate. 4. The inner peripheral wall surface of the opening according to claim 1, wherein the opening width is closer to the evaporation source side than the intermediate portion between the substrate surface of the shadow mask and the evaporation source side plate surface. A shadow mask, characterized in that the inclined surface has a larger inclined surface, and the substrate side of the intermediate portion has an inclined surface having a larger opening width toward the substrate side. 5. The shadow mask according to claim 1, wherein the aperture has a symmetrical shape with respect to a center line of the aperture. 6. The method according to claim 1, wherein the width of the aperture on the surface of the shadow mask plate on the side of the evaporation source is s.
_When the smallest aperture width of the aperture is s ₂ and the thickness of the shadow mask is t, (s ₁ −
shadow mask s ₂₎ the ratio of the _{t (s 1 -s 2) /} t is characterized in that 0.2 to 20. 7. The method according to claim 1, wherein the deposition is performed by disposing the shadow mask according to claim 1 along the substrate between the substrate and the vapor deposition source to form a vapor deposition film on the substrate. Characteristic evaporation method. 8. A deposition method comprising: disposing a shadow mask having a plurality of openings along a substrate between a substrate and a deposition source to perform a deposition process, and forming a deposition film corresponding to the openings on the substrate. In the method, after forming the vapor-deposited film, the shadow mask is subjected to vapor-deposition processing by changing the arrangement direction of the openings, and a vapor-deposited film is formed between the vapor-deposited films already formed. . 9. The vapor deposition method according to claim 8, wherein the shadow mask is the shadow mask according to any one of claims 1 to 6. 10. The vapor deposition method according to claim 7, wherein the organic hole transport layer, the organic light emitting layer, the anode or the cathode of the organic electroluminescent element is formed by a vapor deposition process.