JP2008075168A - Crucible for vapor deposition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a crucible for vapor deposition in which the overflow of molten metal from the opening part thereof can be suppressed, and to provide a crucible for vapor deposition, in which the breakage caused by a difference in a thermal expansion coefficient between a vapor deposition material and the material composing the crucible can be suppressed. <P>SOLUTION: The crucible for vapor deposition is provided with: a storage part for storing and heating the vapor deposition material; and an opening part for releasing the vaporized vapor deposition material to an object for vapor deposition, wherein the opening area is made large toward the edges, and the bottom part of the storage part is thicker than the side face parts of the storage part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a vapor deposition crucible including an accommodating portion for storing and heating a vapor deposition material, and an opening for allowing the vaporized vapor deposition material to be discharged to a vapor deposition target, and a method for manufacturing the same. The present invention relates to an evaporation crucible that is capable of suppressing excessive wetting of molten metal when it is electrically conductive and has a large fluidity when melted, and that can suppress the destruction of a crucible caused by a microcrack interposed on the inner wall of the crucible. Is.

  Thin film technology is the most important technology that supports electronics in hardware. In recent years, the minimum dimensions of devices that make up electronics have shifted to the nanometer range. In order to realize such a device, the material inevitably becomes a thin film, and the fabrication of the material requires a controllability of nanometers to angstroms. On the other hand, industrially, materials and devices must be advanced without impairing productivity, and a technology having atomic level controllability and sufficient thin film formation speed is required. Furthermore, as the functions of devices are diversifying, the thin film forming materials to be controlled are becoming widespread such as semiconductors, magnetic materials, insulators, oxides, dielectrics, metals, and superdielectrics.

  Thin films laminated in this manner are, for example, electrodes for display devices such as liquid crystal display devices and electroluminescence display devices, functional thin films, wiring for printed wiring boards, and resistance films for passive elements formed by built-in printed wiring boards. And a film for controlling optical properties and molecular permeation.

  The thin film formation method used in this way is roughly divided into two methods, that is, a vacuum deposition method and a plasma deposition method. One of these methods, vacuum deposition, is a film deposition technology that was put into practical use prior to plasma deposition, with a simple device structure, easy film thickness control with shutters, etc., and high purity in high vacuum. It is widely used because it has the advantage that it can form a film and the sample is not damaged by plasma as in plasma deposition.

There are several processes for vacuum deposition. First, the entire chamber is evacuated and the vapor deposition material is heated and melted to form a molten metal that is vaporized. The molten metal refers to a vapor deposition material in a molten state in the crucible. Next, the vapor deposition material that has become gas molecules collides with and adheres to the deposition object (sample), whereby a thin film is formed. Methods for heating and melting the crucible and the evaporation material include a resistance heating type, an electron beam type, a high frequency induction type, and a laser type. In order to prevent the vapor deposition material molecules from colliding with the remaining gas molecules in the chamber before reaching the deposition target, and so that the gas molecules themselves do not collide with the deposition target, the degree of vacuum (10 ^{− 3} to 10 ⁻⁴ Pa) is required.

  Among the heating / melting methods, the resistance heating type is generally widely used because the structure of the apparatus is simple. In the resistance heating type, resistance heat is generated by passing an electric current through a container in which the vapor deposition material is accommodated, and the vapor deposition material (vapor deposition source) is heated / melted by the heat to vaporize. When this container is shallow, so-called boat type, if a large amount of vapor deposition material is put in the container and heated, the molten metal will short-circuit between the electrodes and current will not flow through the boat but will flow into the vapor deposition material in the container. There is a problem that the vapor deposition material does not evaporate at all, or the current concentrates on the part where the boat is exposed and burns out there. Therefore, industrially, a method is used in which a crucible capable of charging more vapor deposition material is used, and the crucible is heated with a heater wire such as Ta provided on the outer wall of the crucible, for example. Here, the crucible for vapor deposition refers to a cylindrical heat-resistant container having an accommodating portion for accommodating a vapor deposition material at the bottom, and having an opening on the upper side through which the vaporized vapor deposition material is discharged to a deposition target.

  In such a crucible for vapor deposition, a large amount of vapor deposition material can be charged due to its shape. There was a problem of overflowing from the opening due to rising or bumping. If the vapor deposition material overflows from the opening, the vapor deposition material is wasted, the outer wall of the crucible is damaged, or if the vapor deposition material is conductive, the heating wire or thermocouple gets wet with the molten metal, especially in the heating wire There is a concern that short circuit occurs and breaks.

In order to prevent this, a method of making the crucible opening narrower than the bottom (see, for example, Patent Document 1) has been proposed.
JP 08-269695 A

  However, the method of narrowing the opening portion has the disadvantage that the vaporized vapor deposition material is prevented from being released, and is insufficient to prevent the molten metal having high fluidity from overflowing from the opening portion. Furthermore, the narrow opening has a problem that it is difficult to form a crucible. When forming a crucible by mold-making, it was inefficient that the mold could not be reused or that a work for joining the crucible divided into a plurality of parts was required.

In addition, when using a vapor deposition material with high wettability even if it does not overflow from the opening, the vapor deposition material that has been heated and becomes a molten metal adheres to the inner wall of the crucible. Due to the difference in coefficient of thermal expansion between the material and the material constituting the crucible, there is a concern that the crucible may be cracked and damaged starting from microcracks interposed on the crucible surface. In particular, there is a problem that microcracks are easily formed because residual stress during crucible manufacturing is concentrated in the R portion formed at the bottom of the crucible, and the bottom of the crucible often serves as a starting point for fracture.
A vapor deposition material having such a high wettability can obtain a large fluidity in a high temperature region (1400 ° C. or higher) and can efficiently form a thin film with high in-plane uniformity. However, there was a problem that the deposition crucible was damaged due to fluidity.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vapor deposition crucible that can prevent the molten metal from overflowing from the opening of the crucible.
Another object of the present invention is to provide a vapor deposition crucible that can suppress damage to the crucible due to the difference in thermal expansion coefficient between the vapor deposition material and the material constituting the crucible.

  In order to solve the problems of the present invention, a first invention is provided with an accommodating portion for storing and heating a vapor deposition material, and an opening for discharging the vaporized vapor deposition material to a vapor deposition target. Is a deposition crucible whose opening area is increased toward the edge, wherein the thickness of the bottom portion of the accommodating portion of the crucible is larger than the thickness of the side surface portion of the accommodating portion. It is a crucible.

  A second invention made to solve the problems of the present invention is such that the bottom part of the crucible has a thickness of 0.1 mm to 10 mm, and the side part of the storage part has a thickness of 0.01 mm to 5 mm. The vapor deposition crucible according to claim 1, wherein:

  A third invention made to solve the problem of the present invention is characterized in that the thickness of the edge of the opening of the crucible is larger than the thickness of the opening excluding the edge. Or it is a crucible for vapor deposition of Claim 2.

4th invention made | formed in order to solve the subject of this invention is that the thickness of the edge part of the opening part of the said crucible is 0.1 mm or more and 10 mm or less, The any one of Claim 1 thru | or 3 characterized by the above-mentioned. It is a crucible for vapor deposition as described.

  5th invention made | formed in order to solve the subject of this invention consists of a material selected from the group which the said crucible consists of a ceramic and a metal, In any one of the Claims 1 thru | or 4 characterized by the above-mentioned. It is a crucible for vapor deposition.

A sixth invention made to solve the problems of the present invention is characterized in that the ceramic material is selected from the group consisting of oxide, nitride, carbide and carbon. It is a crucible for vapor deposition as described in above.

  7th invention made | formed in order to solve the subject of this invention, The said metal material is selected from the group which consists of a refractory metal whose melting | fusing point is 2000 degreeC or more, Any one of the Claims 1 thru | or 6 characterized by the above-mentioned. It is a crucible for vapor deposition as described in description.

  Since the vapor deposition crucible of the present invention has a thick bottom portion, the heat conduction is low, and is lower than the temperature applied to the heating portion. Therefore, when the viscosity of the vapor deposition material that has become the molten metal stored in the housing portion at the bottom of the crucible increases, excessive wetting of the molten metal can be suppressed.

  Further, since the thickness up to the opening other than the bottom is thin, the heat conduction is high, and the temperature is substantially equal to the temperature applied to the heating part, that is, the temperature applied to the bottom. For this reason, the viscosity of the molten metal that has been wetted from the bottom is lowered, so that the inner wall of the crucible until the molten metal reaches the opening is quickly wetted, and most of the molten metal is discharged from the opening. Here, since the width of the opening is wider than the width of the bottom, the release of the vapor deposition material is not hindered.

  In addition, because the bottom thickness is increased and the durability of the bottom portion is increased, in the crucible destruction caused by the difference in thermal expansion coefficient between the vapor deposition material and the material constituting the crucible, the bottom portion where many microcracks are present It can be suppressed.

  Furthermore, since the thickness of the edge of the opening becomes thicker than the thickness of the opening other than the edge, the heat conduction is lowered, and the temperature applied to the edge of the opening is lowered. Therefore, when the vapor deposition material that has not been discharged from the opening and remains as a molten metal reaches the edge of the opening, the temperature of the molten metal decreases. As a result, the viscosity of the sheep head increases, and overflow from the edge of the opening can be suppressed. As a result, waste of the vapor deposition material and damage to the outer wall of the crucible can be prevented, and when the vapor deposition material is a conductive material, a short circuit of the electric system of the crucible body and the chamber in which the crucible is housed can be prevented.

  In addition, the crucible of the present invention has partial temperature control by partially changing the thickness of the wall, so that no special processing is required and the manufacture is easy, and the width of the opening is within the crucible. Since it is wider than the width, the mold used to mold the crucible inner wall can be used repeatedly.

  Below, the crucible of this invention is demonstrated.

First, a conventional vapor deposition crucible will be described. FIG. 1 is a schematic cross-sectional view of a conventional crucible. FIG. 1A is a schematic cross-sectional view of a conventional crucible in which a vapor deposition material is charged at the bottom of the crucible and is heated. FIG. 1 (b) shows that the vapor deposition material charged at the bottom of the crucible melts, the molten metal is excessively wetted along the inner wall surface, overflows from the edge of the opening, and comes into contact with the heating unit made of heating wire. It is a cross-sectional schematic diagram which shows a mode that it is.

  In FIG. 1A, the vapor deposition material 2 charged at the bottom of the crucible 1 is melted by being heated by the heating unit 3, and is discharged when the molten metal 2x is wetted along the inner wall surface and reaches the opening. . Here, when the molten metal supply part is the bottom, which is the source of the molten metal, and the opening from which the molten metal is discharged is the discharge part of the molten metal, excess molten metal from the supply part exceeds the amount of molten metal released from the discharge part. When supplied, as shown in FIG. 1 (b), the molten metal 2x overflows from the edge of the opening, wets the heating wire as the heating unit 3, and in particular, the electrical conductivity of the heating unit 3 due to its conductivity. The problem of shorting the heat rays occurs.

  Furthermore, since the vapor deposition material 2 heated to become the molten metal 2x adheres to the inner wall of the crucible, by repeating the temperature up and down in this state, the difference in thermal expansion coefficient between the vapor deposition material and the material constituting the crucible There is a concern that crack breakage may occur in the crucible starting from microcracks interposed on the surface. In particular, the residual stress at the time of crucible manufacture concentrates on the R portion formed on the crucible bottom portion 5, so that microcracks are easily formed, and the crucible bottom portion 5 becomes a starting point for fracture.

  On the other hand, the crucible of the present invention is a vapor deposition crucible characterized in that the thickness of the bottom portion of the housing portion is larger than the thickness of the side surface portion of the housing portion. FIG. 2 shows a schematic cross-sectional view of the crucible of the present invention in which a vapor deposition material is charged at the bottom and heated. FIG. 3 shows a schematic cross-sectional view of the crucible of the present invention. Hereinafter, description will be made based on the schematic cross-sectional views of the crucible of the present invention shown in FIGS.

  The crucible 1 of the present invention has an accommodating portion X and an opening Y, and the opening Y has an opening area that increases toward the edge. That is, the opening Y has a divergent shape. The accommodating part X of the crucible 1 of the present invention includes a bottom part X1 and a side part X2. And the crucible 1 of this invention is characterized by the thickness L1 of the bottom part of an accommodating part being large compared with the thickness L2 of the side part of an accommodating part. Further, the thickness L3 of the edge Y1 of the opening is larger than the thickness L4 of the opening excluding the edge.

  By increasing the thickness L1 of the bottom part X1 of the crucible 1, the heat conduction is lowered, and the temperature applied to the bottom part X1 is lower than the temperature of the side part X2 in contact with the heating part 3. The viscosity of the material (molten metal 3) increases. Therefore, it is possible to suppress an excessive supply of molten metal from the bottom X1.

  Further, since the temperature of the side surface portion X2X1 becomes substantially the same as the temperature applied to the heating portion, the molten metal 2x that has been wetted from the bottom portion has a low viscosity in this portion and can quickly rise to the opening Y. , And discharged at the opening.

  Thus, by making the thickness L1 of the bottom portion larger than the thickness L2 of the side surface portion, the temperature of the bottom portion can be controlled to be lower than the temperature of the side surface portion. Thereby, the supply of the molten metal is suppressed, the temperature of the opening is controlled to be relatively higher than the temperature of the bottom, and the release of the molten metal is promoted, so that the vapor deposition material (molten metal 2x) is melted from the edge Y1 of the opening. ) Can be solved.

  Moreover, about the molten metal which could not be discharged | emitted by the opening part Y, the overflow from an edge can be prevented by making thickness L3 of edge part Y1 of an opening part thicker than thickness L4 of opening parts other than an edge part. . That is, the temperature at the edge Y1 of the opening can be lowered by making the thickness L3 of the edge of the opening thicker than the thickness L4 of the opening other than the edge, and thereby the edge of the opening When Y1 is reached, the temperature of the molten metal decreases and the viscosity increases. And it can suppress that it overflows from the edge of an opening part because the viscosity of a molten metal becomes high.

  Further, the thickness L1 of the bottom portion X1 of the housing portion X is increased, so that the durability is increased, and in the crucible breakage caused by the difference in thermal expansion coefficient between the vapor deposition material 2 and the material constituting the crucible, the bottom portion becomes the breakage starting point. This can be suppressed. That is, the number of times the crucible is used can be increased by increasing the thickness of the bottom.

  In the crucible of the present invention, the thickness L1 of the bottom portion X1 of the housing portion X is preferably 0.1 mm or more and 10 mm or less, and the thickness L2 of the side surface portion X2 of the housing portion X is preferably 0.01 mm or more and 5 mm or less. When the thickness L1 of the bottom is less than 0.1 mm, the heat conduction is increased, and the viscosity of the vapor deposition material (molten metal 2x) in the dissolved state at the bottom X1 is reduced, so that excessive molten metal is supplied from the bottom X1. There is. Further, when the thickness L1 of the bottom portion exceeds 10 mm, the heat conduction becomes too low, and the viscosity of the vapor deposition material (molten metal 2x) becomes excessively high. Therefore, the vapor deposition material (molten metal 2x) from the bottom portion X1 to the side surface portion X2. ) May be in short supply. When the thickness L2 of the side surface portion is less than 0.01 mm, the impact resistance is not sufficient, and the side surface portion may be broken by an external impact. In addition, when the thickness L2 of the side surface portion exceeds 5 mm, the heat conduction becomes low and the viscosity of the molten metal 2x increases, so that the molten metal 2x cannot quickly get wet from the side surface portion X2 to the opening Y. is there.

  In the crucible of the present invention, the thickness L3 of the edge Y1 of the opening Y is preferably 0.1 mm or more and 10 mm or less. When the thickness L3 of the edge is less than 0.1 mm, the heat conduction increases and the viscosity of the molten metal 2x increases, and therefore the molten metal 2x that cannot be evaporated at the opening Y may overflow from the edge. is there. Moreover, when the thickness of the edge exceeds 10 mm, the vapor deposition material evaporated in the opening Y is blocked by the shape of the thick edge, and the film thickness distribution of the vapor deposition layer formed when vapor-deposited on the substrate may be disrupted. is there.

  Since the crucible of the present invention has a great feature in its structure, the material constituting the crucible main body is excellent in heat resistance and can be used as long as it is a material generally used for the production of a crucible for vapor deposition. For example, it is selected from the group consisting of ceramics selected from the group consisting of oxides, nitrides, carbides, carbon, or refractory metal materials such as molybdenum, tantalum, and tungsten. Examples of the ceramic include carbon. Examples of the refractory metal include molybdenum (melting point: 2620 ° C.), tantalum (melting point: 2990 ° C.), tungsten (melting point: 3400 ° C.), and the like. Among these, molybdenum is preferable because it is excellent in processing resistance and is difficult to form a compound with a deposited material.

  Moreover, the crucible of this invention can be manufactured with the shaping | molding method and the cutting method.

  The change in thickness from the bottom to the other opening is preferably changed in a curved line without forming a corner. This is because when the corner is formed, the residual stress due to the vapor deposition material adhering to the inner wall of the crucible is concentrated on the corner and becomes a starting point of crack breakage.

  As the vapor deposition material that can be heated so as to be vapor deposited by the vapor deposition crucible of the present invention, materials such as Al, Ag, Mg, and Au can be used. Can be preferably used. Moreover, a heating wire is used as a heating part.

  In the crucible of the present invention shown in FIG. 3, the bottom thickness L1 = 3.0 mm, the side surface thickness L2 = 1.5 mm, the edge thickness L3 = 4.0 mm, and the opening thickness L4 = 1 excluding the edge. The height of the crucible is H1 = 130 mm, the height of the bottom is H2 = 50 mm, the height of the opening is H3 = 10 mm, the outer diameter of the opening is W1 = 50 mm, the inner diameter of the side of the housing is W2 = A vapor deposition crucible having a width of 35 mm and an edge width W3 = 2.0 mm was prepared. In addition, the material of this vapor deposition crucible was carbon, and it was produced by a mold taking method.

As a vapor deposition material, Al was used, 30 g was put in a vapor deposition crucible, and a thin film made of Al was formed on a glass substrate with a thickness of 150 nm at a degree of vacuum of 3 × 10 ⁻⁴ Pa and a heating temperature of 1500 ° C. When these operations were repeated, a thin film made of Al could be formed on the glass substrate up to 80 times.

(Comparative Example 1)
In the crucible of FIG. 3, the thickness L1 of the bottom portion = the thickness L2 of the side portion = the thickness L3 of the edge portion = the thickness L4 of the opening excluding the edge portion = 1.5 mm, the height H1 of the crucible = 130 mm, An evaporation crucible having a height H2 = 50 mm, an opening height H3 = 10 mm, an outer diameter W1 = 50 mm of the opening portion, and an inner diameter W2 = 35 mm of the side surface portion of the housing portion was prepared. In addition, the material of this vapor deposition crucible was carbon, and it was produced by a mold taking method. As a vapor deposition material, Al was used, 30 g was put in a vapor deposition crucible, and a thin film made of Al was formed on a glass substrate with a thickness of 150 nm at a degree of vacuum of 3 × 10 ⁻⁴ Pa and a heating temperature of 1500 ° C. However, it was confirmed that the vapor deposition material partially overflowed at the edge of the opening of the crucible during the sample exchange. Moreover, when a thin film was repeatedly formed on the glass substrate 30 times, a small scratch was observed at the bottom of the crucible, and it was impossible to deposit further.

It is sectional drawing explaining the conventional crucible. FIG. 2 is a schematic cross-sectional view of a crucible of the present invention in which a vapor deposition material is charged at the bottom and heated. FIG. 3 is a schematic cross-sectional view of the crucible of the present invention.

Explanation of symbols

1: crucible 2: vapor deposition material 2x: molten metal (vapor deposition material)
3: Heating part (heating wire)
X: crucible housing portion X1: bottom X2: side portion Y: crucible opening Y1: edge L1: bottom thickness,
L2: Side thickness L3: Edge thickness L4: Opening thickness excluding the edge H1: Crucible height H2: Bottom height H3: Opening height W1: Opening outer diameter W2 : Inner diameter W3 of side part: Width of edge part of opening part

Claims (7)

A crucible for vapor deposition comprising an accommodating portion for storing and heating the vapor deposition material and an opening for allowing the vaporized vapor deposition material to be discharged to the vapor deposition target, wherein the opening is widened toward the edge. There,
A vapor deposition crucible, wherein a thickness of a bottom portion of the housing portion of the crucible is larger than a thickness of a side surface portion of the housing portion.   The crucible for vapor deposition according to claim 1, wherein a thickness of a bottom portion of the crucible is 0.1 mm or more and 10 mm or less, and a thickness of a side surface portion of the housing portion is 0.01 mm or more and 5 mm or less.   The vapor deposition crucible according to claim 1 or 2, wherein the thickness of the edge of the opening of the crucible is larger than the thickness of the opening excluding the edge.   The crucible for vapor deposition according to any one of claims 1 to 3, wherein a thickness of an edge of the opening of the crucible is 0.1 mm or more and 10 mm or less.   The vapor deposition crucible according to any one of claims 1 to 4, wherein the crucible is made of a material selected from the group consisting of ceramic and metal.   The crucible for vapor deposition according to any one of claims 1 to 5, wherein the ceramic material is selected from the group consisting of oxide, nitride, carbide, and carbon.   The vapor deposition crucible according to any one of claims 1 to 6, wherein the metal material is selected from the group consisting of high melting point metals having a melting point of 2000 ° C or higher.