JP7223632B2 - Evaporation source for vacuum deposition equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a vapor deposition source for a vacuum vapor deposition apparatus which is arranged in a vacuum chamber and which evaporates a solid vapor deposition material and deposits it on an object to be vapor deposited.

For example, in the manufacturing process of an organic EL element, a solid deposition substance (organic material) such as α-NPD is evaporated from a substrate or other object to be deposited in a vacuum atmosphere to form a predetermined thin film on the surface of the object. There is a vapor deposition process, and a vacuum vapor deposition apparatus is widely used for this vapor deposition process. A vapor deposition source used in such a vacuum vapor deposition apparatus is known, for example, from Patent Document 1. This device comprises a crucible with an open upper surface in the vertical direction, and a heating means such as an induction coil for heating the crucible (see the prior art column).

When the crucible is filled with, for example, a powder vapor deposition material in the vapor deposition source of the conventional example and the crucible is heated by a heating means in a vacuum atmosphere, the vapor deposition material in the crucible is melted and then vaporized. The deposition material is vaporized only from the liquid surface facing the upper opening. As a result, there is a problem that the amount of evaporation per unit time under the same pressure is small, and the deposition rate for the object to be deposited is low (that is, productivity is low). In this case, it is conceivable to raise the heating temperature of the crucible. A thin film with the desired film quality cannot be deposited. For this reason, in recent years, there has been a demand for the development of a vapor deposition source for a vacuum vapor deposition apparatus that can obtain a high vapor deposition rate at a relatively low temperature.

Japanese Unexamined Patent Application Publication No. 2010-1529

In view of the above points, the present invention provides a vacuum deposition apparatus that can increase the amount of evaporation per unit time and has a high deposition rate for the object to be evaporated when evaporating the evaporation material and evaporating it onto the object to be evaporated. The object is to provide a vapor deposition source.

In order to solve the above problems, a vapor deposition source for a vacuum vapor deposition apparatus of the present invention, which is arranged in a vacuum chamber and evaporates a solid vapor deposition material to vapor-deposit onto a vapor-deposited object, is directed to the vapor-deposited object. an outer container having a spout for ejecting the vapor deposition material evaporated by the heat, an inner container inserted into the outer container at a distance from the wall surface of the outer container to contain the solid vapor deposition material, and heating of the vapor deposition material in the inner container. and a heating means for enabling the heating, and the inner container is composed of a porous body.

According to the present invention, when the inner vessel of the deposition source is filled with, for example, a powdered vapor deposition material, and the outer vessel is heated, for example, by a heating means in a vacuum atmosphere, the inner vessel is heated by radiant heat from the outer vessel, The heat transfer from the heated inner container melts the deposition material in the inner container. At this time, since the inner container is made of a porous material, the molten vapor deposition material impregnates the pores of the inner container, and the impregnated material is vaporized by the radiant heat from the outer container. , by the conductance of the space between the inner wall surface of the outer container and the outer wall surface of the inner container, it is guided to the ejection port of the outer container through the space, and is scattered from the ejection port toward the object to be vapor-deposited. Become.

As described above, in the present invention, the vaporization amount of the deposition material is added to the vaporization from the liquid surface of the inner container facing the ejection port of the outer container, and the vaporization from the wall surface of the inner container (holes in the wall surface, etc.). can be dramatically increased as compared with the conventional example, and the deposition rate for the object to be deposited can be increased. As a result, the vapor deposition source for the vacuum vapor deposition apparatus of the present invention can obtain a high vapor deposition rate even at a low heating temperature. The gap between the inner container and the outer container is set in the range of 1 mm to 30 mm so that the material impregnated in the pores can be efficiently vaporized while being efficiently heated by radiation from the outer container. .

In the present invention, when the outer container is composed of a crucible with an open upper surface in the vertical direction, the inner container has a bottomed cylindrical profile with an open upper surface, and leg pieces are provided on the outer and lower walls. It is preferably provided. According to this, the inner container can be easily set in the crucible simply by inserting the inner container into the crucible with one leg side down and bringing the leg pieces into contact with the inner bottom wall of the crucible. In addition to the space (first space) between the inner wall of the crucible and the outer wall of the inner container, the vaporized deposition material also passes between the inner bottom wall of the crucible and the outer bottom wall of the inner container. By forming a certain gap that defines the space (second space) (in other words, by allowing the vaporized vapor deposition material to be discharged from the holes in the outer bottom wall of the inner container), the Advantageously, the amount of evaporation can be increased. In this case, if a plurality of spacer members are provided on at least one of the inner wall of the crucible and the outer wall of the inner container, a certain gap defining the first space is formed simply by installing the inner container. Advantageously, the inner container can be positioned concentrically within the crucible so that

In the present invention, if the inner container is made of a carbon-based material having a predetermined porosity, such as graphite, when the vapor deposition substance in the inner container melts, the voids of the inner container are impregnated with the melted vapor deposition substance. It is possible to realize a configuration in which the gas is heated and then vaporized by the radiant heat from the outer container. The porosity of the inner container is appropriately set according to, for example, the melted viscosity of the deposition material used. When the melted vapor deposition material impregnates the pores of the inner container, even if a part of it oozes out and falls on the inner bottom wall of the outer container, the oozed substance remains on the outer wall of the inner container or the outer wall. Anything that falls on the inner bottom wall of the container will quickly vaporize due to radiation and heat transfer from the outer container, so there will be no particular problem.

(a) is sectional drawing which shows typically the vacuum evaporation system provided with the evaporation source of embodiment of this invention. (b) is a cross-sectional view for explaining an exploded vapor deposition source. FIG. 4 is a partially enlarged cross-sectional view showing how a vapor deposition material is scattered from the vapor deposition source of the present invention;

Hereinafter, with reference to the drawings, the object to be vapor-deposited is a glass substrate having a rectangular outline and a predetermined thickness (hereinafter referred to as “substrate Sw”), and the vapor-depositing material is a solid organic material that evaporates (vaporizes via a liquid phase) by heating. An embodiment of the vapor deposition source for the vacuum vapor deposition apparatus of the present invention will be described by taking as an example a case where a predetermined thin film is vapor-deposited on one surface of a substrate Sw using a material Ms. Hereinafter, terms indicating directions such as "upper" and "lower" are based on FIG. 1 showing the installation posture of the vacuum deposition apparatus.

Referring to FIGS. 1 and 2, Dm is a vacuum deposition apparatus provided with the deposition source DS of this embodiment. The vacuum vapor deposition apparatus Dm includes a vacuum chamber 1, which is connected to a vacuum pump through an exhaust pipe (not shown and described), and is evacuated to a predetermined pressure (degree of vacuum) to create a vacuum atmosphere. can be formed. A substrate transfer device 2 is provided above the vacuum chamber 1 . The substrate transfer device 2 has a carrier 21 that holds the substrate Sw with its lower surface as a vapor deposition surface open. It is designed to be transported by Since a known device can be used as the substrate transfer device 2, further explanation is omitted.

A plate-like mask plate 3 is provided between the substrate Sw transported by the substrate transport device 2 and the vapor deposition source DS. In this embodiment, the mask plate 3 is attached integrally with the substrate Sw and transported together with the substrate Sw by the substrate transport device 2 . The mask plate 3 can also be fixedly arranged in the vacuum chamber 1 in advance. The mask plate 3 is formed with a plurality of openings 31 penetrating in the plate thickness direction. A film is formed (deposited) on the substrate Sw. The mask plate 3 may be made of metal such as invar, aluminum, alumina or stainless steel, or made of resin such as polyimide. A 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 deposition source DS has a crucible 4 that constitutes the outer container of this embodiment. The crucible 4 has a bottomed cylindrical profile with an open top in the vertical direction, and is made of a material such as molybdenum, titanium, stainless steel, carbon, or the like, which has good thermal conductivity and a high melting point. In this case, in this embodiment, the top opening 41 of the crucible 4 constitutes the ejection port for the vaporized organic material Mv. Around the crucible 4, a known heating means Ht such as a sheath heater or a lamp heater is provided. Then, the cylindrical body 5 constituting the inner container of this embodiment is inserted into the crucible 4 . The cylindrical body 5 is made of a porous body made of a material having good heat conductivity and a high melting point, specifically, a carbon-based material having a plurality of pores 5a and having a predetermined porosity, such as graphite. , is formed to have a bottomed cylindrical profile. The porosity of the cylindrical body 5 is appropriately set, for example, according to the viscosity of the organic material Ms used for vapor deposition when it melts. be done.

A plurality of rod-shaped leg pieces 52 are erected at intervals on an outer bottom wall (outer lower wall) 51 of the tubular body 5 . A plurality of rod-shaped spacer members 54 are erected on the outer peripheral wall 53 of the cylindrical body 5 at the same height position from the crucible 4 and spaced apart in the circumferential direction. When the cylindrical body 5 is installed in the crucible 4 in the vacuum chamber 1 under atmospheric pressure, the cylindrical body 5 is inserted into the top opening 41 of the crucible 4 from its leg piece 52 side, and each spacer member 54 is inserted into the crucible. The tubular body 5 is moved downward while being slid along the inner peripheral surface 43 of the tubular body 4 . Then, when each leg piece 52 comes into contact with the inner bottom surface 42 of the crucible 4, the cylindrical body 5 is concentrically positioned and installed in the crucible 4, and then the cylindrical body 5 is filled with the solid organic material Ms. In this state, a first space 6a is defined between the inner peripheral surface 43 of the crucible 4 and the outer peripheral wall 53 of the cylindrical body 5, and the gap W1 corresponds to the length of the spacer member 54. Thus, a second space 6b having a gap W2 corresponding to the length of the leg piece 52 is defined between the inner bottom surface 42 of the crucible 4 and the outer bottom wall 51 of the cylindrical body 5. As shown in FIG. In this way, the tubular body 5 is inserted into the crucible 4 with the leg piece 52 side down, and the tubular body 5 is placed in the crucible 4 simply by bringing the leg piece 52 into contact with the inner bottom surface 42 of the crucible 4 . can be easily positioned and set concentrically.

When the crucible 4 is heated by the heating means Ht while the vacuum chamber 1 is in a vacuum atmosphere, the lengths of the leg pieces 52 and the spacer member 54 are such that they can be efficiently heated by the radiation from the crucible 4, while the lengths of the first space are as follows. Due to the conductance of 6a and second space 6b, vaporized substances from wall surfaces 51 and 53 of cylindrical body 5 and holes 5a pass through first space 6a and second space 6b to upper opening 41 of crucible 4, as will be described later. It is set in the range of 1 mm to 30 mm so that it can be efficiently guided. Examples of the organic material Ms used for vapor deposition in the vapor deposition source DS of the present embodiment include α-NPD, which is powdered and filled from the top opening of the cylindrical body 5 .

Here, when the crucible is filled with, for example, a powdery vapor deposition material in the conventional vapor deposition source and the crucible is heated by a heating means in a vacuum atmosphere, the vapor deposition material in the crucible is melted and then vaporized. , the deposition material is vaporized only from the liquid surface facing the top opening of the crucible. As a result, there is a problem that the amount of evaporation per unit time under the same pressure is small, and the deposition rate for the object to be deposited is low (that is, productivity is low). On the other hand, in the vapor deposition source DS of this embodiment, when the organic material Mv is vapor-deposited on the substrate Sw in a vacuum atmosphere, when the crucible 4 is heated by the heating means Ht, radiant heat from the crucible 4 is generated as shown in FIG. The cylindrical body 5 is heated at , and the solid organic material Ms is melted by heat transfer from the heated cylindrical body 5 to become a liquid phase. At this time, since the cylindrical body 5 is made of a porous material, the molten liquid organic material Ml is impregnated into each hole 5a of the cylindrical body 5, and the impregnated material (bleeding from each hole 5a) (including those that come out and remain on the wall surfaces 51 and 53 of the cylindrical body 5) are vaporized by the radiant heat from the crucible 4, and this vaporized organic material Mv is deposited on the inner peripheral surface 43 of the crucible 4 and the outer peripheral wall of the cylindrical body 5. 53 and the second space 6b between the inner bottom wall 42 of the crucible 4 and the outer bottom wall 51 of the cylindrical body 5, the conductance of these first and second spaces 6a , 6b to the top opening 41 of the crucible 4 and scatter toward the substrate Sw.

As described above, in this embodiment, vaporization from the wall surfaces 51 and 53 of the cylindrical body 5 and the holes 5a is added to the liquid surface of the cylindrical body 5 facing the top opening 41 of the crucible 4. , the amount of evaporation can be dramatically increased as compared with the conventional example, and the evaporation rate with respect to the substrate Sw can be increased. As a result, the vapor deposition source DS of this embodiment can obtain a high vapor deposition rate even at a low heating temperature. Here, according to experiments by the present inventors, when the organic material Ms is α-NPD and the cylindrical body 5 as the inner container is made of graphite with a porosity of 35%, the above-mentioned conventional example is different. It was confirmed that about twice the vapor deposition rate was obtained. By heating the crucible 4 with the heating means Ht, even if the hollows 5a of the cylindrical body 5 are impregnated with the molten organic material Ml, even if a part of the material oozes out, the oozing out of the cylindrical body Those remaining on the wall surfaces 51 and 53 of the crucible 4 and those falling on the inner bottom wall 42 of the crucible 4 are rapidly vaporized by radiation and heat transfer from the crucible 4, so no particular problem occurs.

Although the embodiments of the present invention have been described above, various modifications are possible without departing from the scope of the technical idea of the present invention. In the above embodiment, a carbon-based material such as graphite was used as an example of the porous material forming the inner container, but the material is not limited to this, and SiC or the like can be used. Further, in the above-described embodiment, the outer container is configured by the crucible 4 whose upper surface is open. Alternatively, a cover provided with at least one injection nozzle may be attached. In this case, as the outer container, although it is not shown in the drawings and described, it is also possible to use a housing box in which injection nozzles are arranged in a line (a so-called line source).

DS... evaporation source for vacuum evaporation apparatus, Dm... vacuum evaporation apparatus, Ms... solid organic material (solid evaporation material), Ml... melted organic material (evaporation material), Mv... vaporized organic material (vaporized evaporation material) Substance), 1... Vacuum chamber, 4... Crucible (outer container), 41... Upper surface opening (spout), 5... Cylindrical body (inner container), 51... Outer bottom wall of cylindrical body (outside and bottom of inner container wall), Ht... heater (heating means), Sw... substrate (substrate).

Claims (2)

A deposition source for a vacuum deposition apparatus arranged in a vacuum chamber for evaporating a solid deposition material and depositing it on an object to be deposited,
An outer container having a spout for ejecting vapor deposition material toward an object to be vapor-deposited, an inner container inserted into the outer container at a distance from the wall surface of the outer container and containing a solid vapor deposition material, and an interior of the inner container. A vapor deposition source for a vacuum vapor deposition apparatus, comprising a heating means capable of heating the vapor deposition material of (1), and an inner vessel composed of a porous body of a carbon-based material having a predetermined porosity . 2. The vapor deposition source for a vacuum vapor deposition apparatus according to claim 1, wherein the outer container is composed of a crucible having an open upper surface in a vertical direction,
A vapor deposition source for a vacuum vapor deposition apparatus, wherein the inner container has a bottomed cylindrical outline with an open top, and leg pieces are provided on the outer and lower walls thereof.

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