JPH0959767A - Formation of film of alloy using pbn hearth liner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly form an alloy thin film having high purity on a substrate of a large area with good reproducibility by housing an alloy in a PBN hearth liner having the coating of an electrically conductive film on the surface, irradiating the inside with an electron beam and vapor-depositing the alloy thereon. SOLUTION: The surface of the main body of an hearth liner composed of PBN is coated with an electrically conductive film to obtain a PBN hearth liner for electron beam vapor deposition. An alloy 31 of Al-Cu or the like or a componental metal of an alloy is housed in the above PBN hearth liner 21, which is arranged in a hearth 11 made of copper or the like in which cooling water 13 flows through at the bottom part. Next, the surface of the alloy 31 is irradiated with an electron beam. Thus, an electric current flows over the PBN liner 21 through the electrically conductive film, the PBN liner 21 itself is redly heated, which melts the alloy 31 at the inside all over and evaporates the same over the wide area. Furthermore, this PBN is hard to react with alloys, so that the alloy formed film having high purity can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an alloy film forming method using a hearth liner.

[0002]

2. Description of the Related Art As a film forming method for forming a thin film on a substrate for optical parts, electronic parts, etc., electron beam evaporation for irradiating an evaporation material with an electron beam to heat it and evaporating it is generally used. ("Thin Film Engineering Handbook", Ohmsha Publishing, p101-p105, December 10, 1983). An electron gun used as an evaporation source for electron beam evaporation generally includes a plurality of water-cooled copper hearths (crucibles). The hearth is filled with a vapor deposition material directly, and the hearth is rotated as necessary. The evaporation material can be directly irradiated with the electron beam while changing the hearth to be used for the evaporation. However, on the other hand, in many cases, the hearth liner is not directly filled with the vapor deposition material, but an inner container called a hearth liner that is housed in the hearth is used and the vapor deposition material is filled in the hearth liner to be irradiated with an electron beam.

The use of the hearth liner has the following advantages. (1) When cleaning the evaporation source on the evaporation material, the hearth liner, which is a small part, can be taken out and cleaned,
Easy to clean. (2) Even when different vapor deposition materials are vapor-deposited with the same electron gun, only the hearth liner needs to be exchanged, which can sufficiently prevent contamination during vapor deposition.

As a hearth liner, a carbon C hearth liner and the like are known. However, a hearth liner made of a conventional material such as a C hearth liner has poor non-reactivity. For example, when aluminum is subjected to electron beam evaporation using a C hearth liner, carbon reacts with aluminum to cause aluminum carbide (Al ₄ C ₃ ) Occurs, and the crystallinity and purity of the obtained aluminum thin film are reduced.

When the vapor deposition material of the conventional C hearth liner is irradiated with an electron beam, not all of the vapor deposition material in the hearth liner is melted, but only the very vicinity where the electron beam is irradiated is melted. There is a problem that it is difficult to obtain a film thickness distribution of the formed film. for that reason,
There is a limit to reproducibility, and it is difficult to form a thin film having a uniform thickness on a large area substrate. Further, when a wet substance such as aluminum is vapor-deposited with an electron beam, aluminum crawls along the inner wall of the hearth liner, which makes it difficult to observe the molten state and the state of the molten trace is poor.

Further, an alloy thin film is also formed by electron beam evaporation. The biggest problem in the film formation of this alloy is that the evaporation rate of the alloy components is not uniform. For example, in the Al—Cu alloy, the evaporation rate of Al is high. Therefore, when electron beam evaporation of an Al-Cu alloy using a conventional hearth liner, the amount of Cu gradually increases in a narrow range where the electron beam is irradiated, and when the evaporation proceeds to a certain depth, the amount of Cu increases greatly. It becomes impossible to obtain a film within the standard range. Therefore, vapor deposition must be interrupted, and the remaining Al-Cu alloy is wasted.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to solve problems in alloy film formation using a hearth liner.

[0008]

According to the method for forming an alloy of the present invention, an alloy or a component metal of an alloy is stored in a PBN hearth liner for electron beam evaporation in which a surface of a hearth liner body made of PBN is coated with a conductive film. In the hearth liner, the alloy film is formed by irradiating an electron beam and vapor-depositing.

[0009]

1 is an embodiment showing a PBN hearth liner 21 of the present invention arranged in a hearth 11, and FIG. 2 is an enlarged sectional view of the PBN hearth liner 21. As shown in FIG. A PBN hearth liner 21 is housed in a copper hearth 11 cooled by cooling water 13. The PBN hearth liner 21 is a PBN liner body 2 made of PBN.
3 is coated with a conductive film 25, the bottom of which is in contact with the hearth 11 and is cooled by the cooling water 13.

PBN (Pyrolytic Boron)
Nitride: Pyrolytic boron nitride)
CVD (Chemical Vapor Depos)
(ion: chemical vapor deposition method). PBN is insulative. A conductive film 25 is provided on the surface of the PBN hearth liner 21, and the PBN hearth liner 21 has an Al film as a vapor deposition material.
-Alloy 31 such as Cu is filled. When the electron beam is irradiated onto the surface of the alloy 31 from the electron gun to inject electrons,
An electric current flows through the PBN liner main body 23 through the conductive film 25, the PBN liner main body 23 itself becomes red hot, and the internal alloy 3
1 becomes a temperature at which evaporation is possible. At this time, the alloy in the PBN hearth liner 23 is wholly molten, and the alloy 31 evaporates from the entire liquid surface, so that the film thickness distribution can be obtained over a wide area. That is, it is possible to uniformly form a film on a large-area substrate. In addition, the reproducibility becomes better as compared with the conventional hearth liner for the substrate having the same area.

If the conductive film 25 is not applied to P,
If the BN liner main body 23 is directly filled with the alloy 31 and irradiated with an electron beam, the PBN liner main body 23 itself is an insulator, so that there is no escape place for electrons and charge-up occurs. Therefore, in the present invention, the PBN liner body 23 is covered with the conductive film 25 to prevent charge-up. The electrons can leak from the hearth 11 through the conductive film 25.

Further, PBN is extremely difficult to react with molten metal, and a high-purity alloy can be formed into a film. The conductive film 25 may be made of any material and may be formed by any method, but a material that does not easily react with the molten metal is preferable in terms of utilizing the characteristics of PBN.
A PG film is a typical example of such a conductive film 25. Here, the PG film is a pyrolytic graph.
ite (pyrrolytic graphite), PB
It can be manufactured by the same method as N. Since PBN is produced by using a thermal decomposition method, the PBN liner main body 23 has a kind of laminated film structure as shown in FIG. 4 when viewed microscopically. And have anisotropy.

Due to the heat conduction characteristic of PBN, the heat conduction in the plane direction is large, and the temperature distribution of the PBN hearth liner 21 becomes uniform. On the other hand, the thermal conductivity in the thickness direction is much smaller than that in the plane direction and the heat retention is excellent, and the vapor deposition can be efficiently performed with a small electron beam power. In addition, even a leaky metal such as Al does not crawl on the inner wall surface of the PBN hearth liner 21, which does not hinder the inspection of the molten state and does not cause troublesome cleaning even after the vapor deposition process.

On the other hand, however, there is a problem because PBN has a laminated structure. As shown in FIG. 3, the end of the laminated structure is exposed at the opening end face 23a of the container-shaped PBN liner main body 23, and the foreign matter invades from the interlayer to cause PB
The N laminated structure is easily damaged. In the embodiment of the present invention shown in FIGS. 1 and 2, the opening end face 23a is covered and protected by the conductive film 25 to prevent the above damage.

FIG. 4 is a sectional view showing another embodiment of the PBN hearth liner of the present invention, which is different only in the position where the conductive film 25 is formed. The conductive film 25 'is a container-shaped PBN.
The opening end face 23a of the liner body 23 is covered and protected. When electrons are injected into the alloy 31 by the electron beam, it cannot leak into the sheath 11 as in the embodiments of FIGS. 1 and 2, but the presence of the conductor film 25 ′ causes reflection electrons and secondary electrons. Leakage in the form of electrons, thermoelectrons, etc. will not occur and electrons will not accumulate in the alloy 31 to cause charge-up.

Among metals, alloys are considered to be difficult to stably deposit a film having a uniform composition. But,
By using the PBN hearth liner of the present invention, an alloy film having a uniform composition can be formed.

The vapor deposition of the following alloys will be described with reference to FIGS. 1 and 2, focusing on the case of an Al--Cu alloy. A
When an alloy 31 such as 1-Cu is loaded into the PBN hearth liner 21 and an electron beam is applied, the PBN liner body 23
The red heat of itself melts the entire alloy 31, and the molten alloy 31 convects between the surface and the bottom. The Al-Cu alloy has a higher evaporation rate of Al. If there is no overall melting and convection, and evaporation in a narrow area of the surface is repeated toward the bottom, the Al concentration will gradually decrease and the Cu concentration will gradually increase until the target permissible standard is reached. Film formation of the composition becomes difficult, and this state is reached relatively quickly.

On the other hand, in the present invention, as described above, A
Since the entire l-Cu alloy melts and convection occurs, even if a large amount of Al evaporates in the surface layer of the alloy 31 compared with Cu, the composition varies depending on the total amount of the alloy 31 due to uniform mixing due to convection. In terms of the total amount, the amount of Al evaporated excessively with respect to Cu is small. Therefore, the Al / Cu ratio within the allowable range can be maintained for a long period of time.

Further, in the case of an alloy such as Al-Cu, since the evaporation rate of the components is different, the balance of the components will eventually be destroyed, and it is not possible to use all of the alloy filled in the hearth liner. Therefore, processing of this residual vapor deposition material becomes a problem. As described above, in the conventional technique, the surface portion of the remaining vapor deposition material has an extremely large amount of Cu, while the bottom portion is cooled by the cooling water 13 of the hearth 11 and does not evaporate, and the original Al-Cu ratio is It is retained and compositionally different. Such residual vapor deposition material cannot be reused and must be discarded.

On the other hand, in the present invention, since the mixing and homogenization by convection is always repeated, the remaining vapor deposition material (alloy) has a uniform composition. Since this composition can be obtained empirically or by measurement, the remaining vapor deposition material can be reused if Al and Cu are added at a ratio of the initial concentration. Prior to vapor deposition, the entire regenerated vapor deposition material is melted and homogenized by convection to return to the initial state. This means that the composition of the alloy (vapor deposition material) in the PBN hearth liner at the start of film formation can be arbitrarily adjusted by appropriately changing the composition of the vapor deposition material (alloy) added.

Further, by using the hearth liner of the present invention, two or more pure metals are combined to form an alloy of PB.
It can be produced in the N hearth liner. Its composition can be freely adjusted by the mass of each metal charged in the PBN hearth liner.

[0022]

According to the present invention, the following operational effects can be obtained by using the PBN hearth liner. (1) Since the metal evaporates from the entire liquid surface, the film thickness distribution can be obtained over a wide area, the reproducibility can be improved, and uniform film formation can be performed on a large area substrate. (2) Since the reactivity with the molten metal is low, a high-purity alloy film can be formed. (3) Since it has anisotropy in the plane direction and the thickness direction, it is excellent in heat retention, can be vapor-deposited with a small electron beam power, and does not crawl even with a metal that is easily wetted such as Al. (4) It melts the whole body and evaporates what is always convected and homogenized, so that an alloy film with a uniform composition can be formed for a long period of time, the remaining alloy can be reused after the stop, and the alloy can be adjusted in the hearth liner. Is also possible.

[Brief description of drawings]

FIG. 1 is a sectional view showing a state in which a PBN hearth liner according to an embodiment of the present invention is set in a hearth.

2 is a cross-sectional view of the PBN hearth liner of FIG.

FIG. 3 is a schematic explanatory view that the PBN hearth liner has a laminated structure.

FIG. 4 is a sectional view showing another embodiment of the PBN hearth liner of the present invention.

[Explanation of symbols]

 11 Hearth 13 Cooling Water 21 PBN Hearth Liner 23 PBN Liner Main Body 25, 25 'Conductive Film 31 Alloy

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] February 19, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction contents]

PBN (Pyrolytic Boron)
Nitride: Pyrolytic boron nitride)
CVD (Chemical Vapor Depos)
(ion: chemical vapor deposition method). PBN is insulative. A conductive film 25 is provided on the surface of the PBN hearth liner 21, and the PBN hearth liner 21 has an Al film as a vapor deposition material.
-Alloy 31 such as Cu is filled. When the electron beam is irradiated onto the surface of the alloy 31 from the electron gun to inject electrons,
Current flows through the PBN liner 21 through the conductive film 25,
The PBN liner 21 itself becomes red hot, and the temperature of the alloy 31 in the inside thereof reaches a temperature at which evaporation is possible. At this time, PBN hearth liner 21
The alloy inside is entirely molten, and alloy 3
1 evaporates and a film thickness distribution can be obtained over a wide area. That is, it is possible to uniformly form a film on a large-area substrate. In addition, the reproducibility becomes better as compared with the conventional hearth liner for the substrate having the same area.

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

Further, PBN is extremely difficult to react with molten metal, and a high-purity alloy can be formed into a film. The conductive film 25 may be made of any material and may be formed by any method, but a material that does not easily react with the molten metal is preferable in terms of utilizing the characteristics of PBN.
A PG film is a typical example of such a conductive film 25. Here, the PG film is a pyrolytic graph.
refers to ite (pyrolytic graphite), P
It can be manufactured by the same method as BN. Since PBN is produced by using a thermal decomposition method, the PBN liner main body 23 has a kind of laminated film structure as shown in FIG. 3 when viewed microscopically .
The plane direction and the thickness direction of the laminated film have anisotropy.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0015

[Correction method] Change

[Correction contents]

FIG. 4 is a sectional view showing another embodiment of the PBN hearth liner of the present invention, which is different only in the position where the conductive film 25 is formed. The conductive film 25 'is a container-shaped PBN.
The opening end face 23a of the liner body 23 is covered and protected. When electrons alloy 31 is turned by an electron beam, Figure 1, can not be leaked to the wafer over scan 11 as in the embodiment of FIG. 2, the conductive film 25 'is present, the reflected electrons, There will be no leakage in the form of secondary electrons, thermoelectrons, etc., and electrons will not accumulate in the alloy 31 to cause charge-up.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction contents]

The vapor deposition of the following alloys will be described with reference to FIGS. 1 and 2, focusing on the case of an Al--Cu alloy. A
When an alloy 31 such as l-Cu is loaded into the PBN hearth liner 21 and an electron beam is applied, the entire alloy 31 is melted by the red heat of the PBN liner 21 itself, and the molten alloy 3
1 convection between the surface and the bottom. The Al-Cu alloy has a higher evaporation rate of Al. If there is no overall melting and convection, and evaporation in a narrow area of the surface is repeated toward the bottom, the Al concentration gradually decreases and Cu
The concentration increases, and finally it becomes difficult to form a film having a desired permissible standard composition, and this state is reached relatively quickly.

[Procedure Amendment 5]

[Document name to be amended] Drawing

[Correction target item name] Fig. 4

[Correction method] Change

[Correction contents]

FIG. 4

Claims (1)

[Claims] 1. An alloy or a component metal of an alloy is housed in a PBN hearth liner for electron beam evaporation in which the surface of a hearth liner body made of PBN is coated with a conductive film, and the alloy is formed by irradiating the hearth liner with an electron beam for vapor deposition. A method for forming an alloy, comprising: forming a film.