CN111108230A

CN111108230A - Evaporation source for vacuum evaporation device

Info

Publication number: CN111108230A
Application number: CN201980004684.3A
Authority: CN
Inventors: 中村寿充; 清健介
Original assignee: Ulvac Inc
Current assignee: Ulvac Inc
Priority date: 2018-06-08
Filing date: 2019-05-08
Publication date: 2020-05-05
Also published as: JP6918233B2; JPWO2019235118A1; KR102453030B1; WO2019235118A1; KR20210002607A; TW202000955A

Abstract

The invention provides a vapor deposition source for a vacuum vapor deposition device, which can increase the sublimation amount per unit time when depositing a sublimable material and has a high vapor deposition rate on a vapor deposition object. A vapor Deposition Source (DS) for a vacuum vapor deposition device (Dm) is arranged in a vacuum chamber (1) and is used for sublimating a sublimable organic material (7) and performing vapor deposition on a vapor deposition object (Sw), and the DS comprises: an upper surface opening (4) having a crucible (41) for ejecting a sublimated material toward the deposition object (Sw); a cylindrical body (5) which is inserted into the upper surface opening (4) with a space from the wall surface of the upper surface opening (4) and which contains a sublimable material; and a heating unit (Ht) which can heat the material in the cylindrical body (5); the cylindrical body (5) is provided with a plurality of meshes (52) which allow the sublimated material to communicate with each other.

Description

Evaporation source for vacuum evaporation device

Technical Field

The present invention relates to a vapor deposition source for a vacuum vapor deposition apparatus, which is disposed in a vacuum chamber and is configured to sublimate a sublimable material and to vapor-deposit an object to be vapor-deposited.

Background

For example, in the process of manufacturing an organic EL device, quinoline aluminum complex (Alq) is present₃) And a step of depositing a sublimable material (organic material) such as an aromatic diamine on a deposition target such as a substrate in a vacuum atmosphere, and vacuum deposition apparatuses are widely used in the deposition step. A vapor deposition source used in such a vacuum vapor deposition apparatus is known, for example, from patent document 1. The device is provided with: a crucible having an upper surface opened in a vertical direction; and a heating unit such as an induction coil for heating the crucible (see the prior art column).

Here, the above-mentioned materials generally have a poor thermal conductivity and, unlike materials that vaporize through a liquid phase, do not generate convection of the materials in the crucible when heated. Therefore, in the evaporation source of the above conventional example, when a powdery material is filled in the crucible and the crucible is heated by the heating means in a vacuum atmosphere, for example, the material in contact with the crucible wall surface that directly transfers heat is sublimated. At this time, the sublimated material is scattered toward the evaporation target through the upper surface opening of the crucible from the upper layer portion of the filled material facing the upper surface opening of the crucible, but the sublimated material collides with the material at a lower layer portion located further below and having a lower temperature (in other words, not heated to the sublimation temperature) located therearound to return to a solid state. As a result, the sublimated material is scattered only from a limited range, and the sublimation amount per unit time is small under the same pressure, and the evaporation rate of the material to be evaporated is low (that is, the production rate is low). In this case, it is conceivable to raise the heating temperature of the crucible, but in the case of (organic) materials such as quinoline aluminum complexes and aromatic diamines, if the heating temperature is raised, the materials decompose at the evaporation source, and a thin film having a desired film quality that determines the performance of the element cannot be evaporated. Therefore, in recent years, there has been a demand for development of a vapor deposition source that can achieve a high vapor deposition rate at a relatively low temperature, as a vapor deposition source for a vacuum vapor deposition apparatus for depositing a sublimable material of the above-mentioned kind.

Documents of the prior art

Patent document

[ patent document 1 ] Japanese patent laid-open No. 2010-1529

Disclosure of Invention

Technical problem to be solved by the invention

In view of the above, an object of the present invention is to provide a vapor deposition source for a vacuum vapor deposition device, which can increase the sublimation amount per unit time and increase the vapor deposition rate on a vapor deposition object when depositing a sublimable material.

Means for solving the problems

In order to solve the above-described problems, a vapor deposition source for a vacuum vapor deposition apparatus according to the present invention is a vapor deposition source for a vacuum vapor deposition apparatus, which is disposed in a vacuum chamber, and which sublimates a sublimable material to deposit a vapor deposition target, the vapor deposition source comprising: an outer container having an ejection port for ejecting a sublimated material toward an evaporation target; an inner container inserted into the outer container with a space from a wall surface of the outer container, and containing a sublimable material; and a heating unit which can heat the material in the inner container; the inner container is provided with a plurality of through holes allowing the sublimated material to be communicated.

With the present invention, for example, a sublimable material in powder form is filled into the inner container of the vapor deposition source, and when the outer container is heated in a vacuum atmosphere, for example, by a heating unit, sublimation is started from the material directly heated by heat radiation from the outer container through the through holes and the material directly transferring heat from the inner container heated by the heat radiation. The sublimated material is guided from each through hole to the discharge port of the outer container through the space by thermal conduction (コンダクタンス) of the space between the inner wall surface of the outer container and the outer wall surface of the inner container, and is scattered from the discharge port to the evaporation object. As described above, in the present invention, since the sublimated material is basically taken out to each through hole and returned to a solid state by collision with a material having a relatively low temperature (i.e., a non-heating material) is suppressed as much as possible (in other words, since the area over which the sublimated material is scattered is increased), the sublimation amount is significantly increased as compared with the above conventional example in which the sublimated material is scattered only from a limited range, and the vapor deposition rate on the vapor deposition target can be increased. Accordingly, the vapor deposition source for a vacuum vapor deposition apparatus of the present invention can obtain a high vapor deposition rate even at a low heating temperature, and is therefore most suitable for vapor deposition of organic materials such as quinoline aluminum complexes and aromatic diamines. Further, the gap between the inner container and the outer container is set in the range of 1mm to 30mm so that the heating can be efficiently performed by the radiation from the outer container and the sublimated material can be efficiently taken out from each through hole to the ejection port of the outer container through the space.

In the present invention, when the outer container is formed of a crucible having an upper surface opened in a vertical direction, the inner container may be formed of a bottomed cylindrical body having an upper surface opened, and the outer bottom wall of the cylindrical body may be provided with leg pieces. In this way, the inner container is inserted into the crucible with the leg side down, and the inner container is simply mounted in the crucible by bringing the leg into contact with only the inner bottom wall of the crucible, and in this state, a certain gap is formed between the inner bottom wall of the crucible and the outer bottom wall of the inner container, in addition to the space (first space) between the inner side wall of the crucible and the outer side wall of the inner container, to define a space (second space) through which the sublimated material passes, thereby further increasing the sublimation amount. In this case, if a plurality of spacers are provided on at least one of the inner wall of the crucible and the outer wall of the inner container, it is advantageous that the inner container is concentrically positioned in the crucible so as to form a certain gap defining the first space by simply providing the inner container.

In the present invention, the tubular body may be formed of a porous body having a plurality of fine pores through which vapor passes, such as a porous ceramic, on the one hand, a product in which metal wire rods having a predetermined diameter are assembled into a lattice shape, such as a metal mesh, a product in which a metal plate material is provided with circular or slit-shaped openings (through holes) through which vapor passes, such as a punched metal, or a product in which an expanded metal mesh (エキスパンドメタル) is formed into a tubular shape. The tubular body may be formed by winding a product having a thickness obtained by overlapping a plurality of metal meshes and a metal wire into a nonwoven fabric, as long as the tubular body has through holes through which steam passes. For example, when the cylindrical body is formed of a metal mesh, the wire diameter is preferably in the range of Φ 0.2 to 1.0mm, and the mesh size of the through holes as the material allowing the communication of the sublimated material is preferably in the range of #10 to # 50. In the case of such a metal mesh, even if a powdery material is filled, the sublimable material (organic material) such as quinoline aluminum complex and aromatic diamine generally has cohesive force and therefore can be deposited without substantially leaking out of each mesh, and even if a part of the sublimable material leaks out, the sublimable material is merely deposited on the inner bottom wall of the outer container and thereafter sublimated when the outer container is heated, and therefore there is no particular problem.

Drawings

Fig. 1(a) is a sectional view showing a vacuum vapor deposition device including a vapor deposition source according to an embodiment of the present invention, and (b) is a sectional view for explaining the vapor deposition source in an exploded manner.

Fig. 2(a) is a partially enlarged cross-sectional view showing a scattering state of a sublimated material from a vapor deposition source of the present invention, and (b) is a partially enlarged cross-sectional view showing a scattering state of a sublimated material from a vapor deposition source of a conventional example.

Fig. 3 is a graph illustrating changes in the vapor deposition rate with respect to the heating temperature.

Detailed Description

An embodiment of a vapor deposition source for a vacuum vapor deposition device according to the present invention will be described below by taking, as an example, a case where a glass substrate having a rectangular outline and a predetermined thickness (hereinafter referred to as "substrate Sw") is used as a substance to be vapor deposited, a sublimable organic material is used as a vapor-deposited substance, and a predetermined thin film is deposited on one surface of substrate Sw. The directional terms such as "up" and "down" are based on fig. 1 showing the installation posture of the vacuum vapor deposition apparatus.

Referring to fig. 1, Dm denotes a vacuum vapor deposition apparatus including a vapor deposition source DS according to the present embodiment. The vacuum deposition apparatus Dm includes a vacuum chamber 1, and although not particularly illustrated, the vacuum chamber 1 is connected to a vacuum pump through an exhaust pipe, and is capable of being evacuated to a predetermined pressure (vacuum degree) to form a vacuum atmosphere. Further, a substrate transfer device 2 is provided above the vacuum chamber 1. The substrate transport apparatus 2 includes a carrier 21 for holding the substrate Sw in a state where the lower surface as a deposition surface is open, and the carrier 21 and further the substrate Sw are moved in a direction in the vacuum chamber 1 at a predetermined speed by a driving device not shown. A known apparatus may be used as the substrate transfer apparatus 2, and thus a detailed description thereof will be omitted.

A plate-like mask plate 3 is provided between the substrate Sw conveyed by the substrate conveying device 2 and the deposition source DS. In the present embodiment, the mask plate 3 is integrally assembled with the substrate Sw and is conveyed by the substrate conveying device 2 together with the substrate Sw. The mask plate 3 may be fixed and arranged in the vacuum chamber 1. A plurality of openings 31 penetrating the mask plate 3 in the thickness direction of the plate are formed, and the vapor deposition range of the sublimated material on the substrate Sw is restricted by the positions where the openings 31 are not formed, whereby a predetermined pattern can be formed (vapor deposited) on the substrate Sw. As the mask 3, a resin material such as polyimide may be used in addition to a metal material such as invar steel, aluminum, alumina, and stainless steel. The vapor deposition source DS of the present embodiment is provided on the bottom surface of the vacuum chamber 1 so as to face the substrate Sw.

The vapor deposition source DS has a crucible 4 constituting an outer container of the present embodiment. The crucible 4 has a bottomed cylindrical profile with an upper surface opened in the vertical direction, and is formed of a high melting point material having good heat conduction, such as molybdenum, titanium, stainless steel, or carbon. At this time, the upper surface opening 41 of the crucible 4 constitutes an ejection port for the sublimated material in the present embodiment. Heating means Ht made of a known product such as a sheath heater or a heating lamp is provided around the crucible 4. A cylindrical body 5 constituting the inner container of the present embodiment is inserted into the crucible 4. The tubular body 5 is made of a high melting point material having good heat conductivity, such as molybdenum, titanium, and stainless steel, like the crucible 4, and in the present embodiment, the tubular body 5 is formed by forming a metal mesh into a tubular body having a bottomed tubular outline, the metal mesh is assembled into a lattice shape by the wire rods 51, and a part of each mesh 52 of the metal mesh constitutes the through hole of the present embodiment. In this case, the wire 51 preferably has a wire diameter in the range of Φ 0.2 to 1.0mm, and the mesh 52 preferably has a size in the range of #10 to # 50. On the one hand, when the mesh (opening) 52 is too large, there is a problem that the material cannot be held, and on the other hand, when the mesh (opening) 52 is too small, there is a problem that the passage of the sublimated material is hindered.

A plurality of rod-shaped leg pieces 54 are vertically provided at intervals on the outer bottom wall 53 of the cylindrical body 5. Further, a plurality of rod-like spacers 56 are vertically provided on the outer peripheral wall 55 of the cylindrical body 5 constituting the outer wall of the present embodiment at the same height from the inner bottom wall 42 of the crucible 4 and at intervals in the circumferential direction. When the cylindrical body 5 is set on the crucible 4 in the vacuum chamber 1 under atmospheric pressure, the cylindrical body 5 is inserted into the upper surface opening 41 of the crucible 4 from the leg piece 54 side thereof, and the cylindrical body 5 is moved downward while each spacer 56 is slid along the inner peripheral surface 43 of the crucible 4 constituting the inner side wall in the present embodiment. When the leg pieces 54 abut against the inner bottom surface 42 of the crucible 4, the cylindrical body 5 is concentrically positioned and set in the crucible 4. In this state, a first space 6a formed by the slit W1 corresponding to the length of the spacer 56 is defined between the inner peripheral surface 43 of the crucible 4 and the outer peripheral wall 55 of the cylindrical body 5, and a second space 6b formed by the slit W2 corresponding to the length of the spacer 56 is defined between the inner bottom surface 42 of the crucible 4 and the outer bottom wall 53 of the cylindrical body 5.

The length of the leg pieces 54 and the spacer 56 is set in the range of 1mm to 30mm so that: on the one hand, when the crucible 4 is heated by the heating unit Ht in a state where the vacuum chamber 1 is set as a vacuum atmosphere, it can be efficiently heated by radiation from this crucible 4, and on the other hand, by thermal conduction of the first space 6a and the second space 6b, the sublimated organic material can be efficiently guided from each mesh 52 of the metal mesh to the upper surface opening 4 of the crucible 4 through the first space 6a and the second space 6 b. After the tubular body 5 is inserted into the crucible 4, the tubular body 5 is filled with the sublimable organic material 7.

The organic material 7 for vapor deposition in the vapor deposition source of the present embodiment may, for example, be aluminum quinolate blended thereinSubstance (Alq)₃) And an aromatic diamine or the like, and the powdery organic material 7 is filled from the upper surface opening of the cylindrical body 5. Even if the organic material 7 in powder form is filled in the cylindrical body 5 in this way, the organic material 7 has cohesive force and can be deposited without leaking out of the respective meshes 52 of the metal mesh. Even if some of the leakage occurs, the leakage is accumulated only on the inner bottom surface 42 of the crucible 4, and the leakage sublimates when the crucible 4 is heated thereafter, and is guided to the upper surface opening 41 of the crucible 4 through the first space 6a and the second space 6b, thereby causing no particular problem.

Here, the organic material 7 as described above generally has a poor thermal conductivity, and unlike a material vaporized in a liquid phase, convection of the material in the crucible does not occur during heating. Therefore, when the organic material 7 is directly filled in the crucible Pc and vapor deposition is performed as in the conventional example, if the crucible Pc is heated by a heating means (not shown), sublimation starts from the organic material 7 in contact with the wall surface of the crucible Pc that directly transfers heat, but from the upper layer Pu of the filled organic material 7 facing the upper surface opening Po of the crucible Pc, the sublimated organic material 7a is scattered toward the substrate (not shown) through the upper surface opening Po of the crucible Pc, whereas the sublimated organic material 7b in the lower layer Pd collides with the lower temperature (in other words, not heated to the sublimation temperature) organic material 7 existing in the periphery thereof, and returns to a solid state, as shown in fig. 2 (a). As a result, the sublimated organic material 7 can be scattered only from a limited range, and the sublimation amount per unit time is small at the same pressure, and the vapor deposition rate on the vapor deposition object is low.

In contrast, in the vapor deposition source DS of the present embodiment, when the organic material 7 is vapor deposited on the substrate Sw in a vacuum atmosphere, if the crucible 4 is heated by the heating unit Ht, sublimation is started from the organic material 7 directly heated by heat radiation from the crucible through each mesh 52 and the organic material 7 directly heat-transferred from the wire 51 of the metal mesh heated by the heat radiation. The sublimated organic material 71 is guided from the upper layer portion of the filled organic material 7 to the upper surface opening 41 of the crucible 4 directly through the upper surface opening 41 of the crucible 4, and from the lower layer portion of the filled organic material 7 to the upper surface opening 41 of the crucible 4 through the first space 6a and the second space 6b by thermal conduction through the first space 6a and the second space 6b, and is scattered from the ejection port to the substrate Sw.

In this way, in the present embodiment, since the sublimated organic material 71 is basically taken out from each mesh 52 of the metal mesh and returned to a solid state by colliding with a material having a relatively low temperature (i.e., a non-heating material) is suppressed as much as possible (in other words, since the area over which the sublimated material is scattered is increased), the sublimation amount is significantly increased as compared to the above conventional example in which the sublimated material is scattered only from a limited range, and the vapor deposition rate on the vapor deposition target can be increased. That is, as shown in FIG. 3, when the vapor deposition rate was measured with respect to the heating temperature of the crucible 4, Pc, the vapor deposition rate was 1.1 to 2 times as high as that obtained in the embodiment of the present invention shown by the line- ● -compared with the conventional example shown by the line-good-line.

The embodiments of the present invention have been described above. However, various modifications may be made without departing from the scope of the technical idea of the present invention. In the above embodiment, the inner container is exemplified by a product in which a metal mesh is formed into a cylindrical shape, but the inner container is not limited to this, and on the one hand, a product in which a metal plate material such as a punched metal is provided with circular or slit-shaped openings (through holes) is formed into a cylindrical shape, or a product in which a metal expanded mesh is formed into a cylindrical shape may be used, and on the other hand, the cylindrical body may be made of porous ceramics, and further, the bottom wall of the inner container does not necessarily have to have through holes. In this case, the hole diameter of the through-holes is not particularly limited as long as the sublimated organic material can pass through the through-holes, and the total area ratio of all the through-holes to the outer surface of the cylindrical body is appropriately set according to the vapor deposition rate.

In the above embodiment, the outer container is described as an example of a product having the crucible 4 with an open top, but a lid provided with at least one nozzle may be attached to the top surface of the crucible 4 in order to adjust the thermal conductance of the first space 6a and the second space 6 b. At this time, although not particularly illustrated, a product (so-called line source) in which nozzles are arranged on the upper surface of the storage box may be used as the outer container.

Description of the reference numerals

Dm. vacuum vapor deposition apparatus, DS. vacuum vapor deposition apparatus used vapor deposition source, Ht. heating unit, Sw. substrate (evaporation object), 1 vacuum chamber, 4 crucible (outer container), 41, upper surface opening (spout), 5, cylindrical body (inner container), 52 mesh (through hole).

Claims

1. A vapor deposition source for a vacuum vapor deposition apparatus, which is disposed in a vacuum chamber and is used for sublimating a sublimable material and performing vapor deposition on a vapor deposition object, characterized in that:

comprising: an outer container having an ejection port for ejecting a sublimated material toward an evaporation target; an inner container inserted into the outer container with a space from a wall surface of the outer container and containing a sublimable material; and a heating unit which can heat the material in the inner container;

the inner container is provided with a plurality of through holes allowing the sublimated material to be communicated.

2. The vapor deposition source according to claim 1, wherein:

the outer container is constituted by a crucible having an upper surface opened in a vertical direction,

the inner container is formed of a bottomed cylindrical body having an open upper surface, and a leg piece is provided on an outer bottom wall of the cylindrical body.