JP2001081549A - Electron beam vapor deposition method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electron beam vapor deposition method capable of depositing a dense and homogeneous film while preventing the coarsening of evaporated particles. SOLUTION: A liner member 24 is interposed between a crucible 21 and an evaporation material 23 to prevent heat transfer from the evaporation material 23 to the crucible 21 and stabilize the output of an electron beam EB. Simultaneously, the output of the electron beam EB is maintained at low values so that the deposition rate of the evaporation material 23 becomes <=5 Å/s to prevent the coarsening of the evaporated particles due to the bumping of the evaporation material 23.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam evaporation method for forming a film by irradiating an evaporation material with an electron beam, heating and evaporating the material.

[0002]

2. Description of the Related Art An electron beam evaporation method is a thin film forming technique in which a target evaporation material is irradiated with an electron beam and heated to evaporate to form a thin film. It can be used for all materials including refractory metals. ing.

[0003] In the film formation by the conventional electron beam evaporation method in the semiconductor manufacturing process, an ingot (mass) of the evaporation material 13 is put into the accommodating portion 12 of a copper (Cu) crucible 11 in which a cooling water circulation pipe is provided. By irradiating the evaporation material 13 with an electron beam EB under reduced pressure, the evaporation material 13 is heated and evaporated, and the evaporation material 13 is placed on a substrate (not shown).
3 are formed.

[0004]

The problem here is that the heat of the evaporation material 13, which is heated by the irradiation of the electron beam EB, escapes to the crucible 11 provided with the cooling means, so that the evaporation is efficiently performed. Not only cannot the material be heated, but also the output of the electron beam EB cannot be stabilized. As a result, the irradiation area of the electron beam EB is rapidly heated locally, which easily causes bumping, and coarse particles as large as several μm are easily generated. In such a case, it becomes impossible to form a dense and uniform thin film, and irregularities are generated on the film surface, which causes various processing defects in a subsequent fine processing step.

[0005] Such a problem is caused particularly when the evaporation material is gold (A).
In the case of u), pinholes, poor insulation, or poor wiring are caused by coarse evaporated particles of Au.

The present invention has been made in view of the above problems, and has as its object to provide an electron beam vapor deposition method capable of forming a dense and uniform film while suppressing coarsening of evaporated particles.

[0007]

In order to solve the above-mentioned problems, the present invention provides a liner member interposed between a crucible and an evaporating material to suppress heat transfer from the evaporating material to the crucible. At the same time as stabilizing the output of the electron beam, the output of the electron beam is kept small so that the deposition rate of the evaporation material is 5 ° / s or less, and the coarsening of the evaporation particles due to bumping of the evaporation material is suppressed. .

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 to FIG. 3 show an embodiment of the present invention. The electron beam evaporation apparatus provided in the present embodiment is configured as shown in FIG.
, A crystal oscillation type film thickness meter 16, and an electron beam source 18
A control unit 17 for controlling the output of the electron beam source 18 based on the output of the crystal oscillation type film thickness meter 16;
3 is provided.

Referring to FIG. 2, a crucible 21 constituting an evaporation source is made of copper (Cu) and has a cooling water circulation pipe therein even though not shown. A cup-shaped liner member 24 made of molybdenum (Mo) as shown in FIG. 3 is applied to the entire area of the accommodating portion 22 of the crucible 21, and an ingot (mass) of the evaporation material 23 is placed inside the liner member 24. Is accommodated. The liner member 24 is formed to a thickness of about 5 mm, and has sufficient strength against expansion and contraction due to heating of the evaporation material. Here, in the present embodiment, gold (A) serving as a wiring film is used for a substrate W configured as a semiconductor substrate.
u) is the evaporation material 23.

The quartz film thickness gauge 16 has a known configuration, and measures the film thickness from the natural frequency of quartz which fluctuates due to the attachment and deposition of evaporated particles of the evaporation material 23 during film formation.
The output of the electron beam EB generated from the electron beam source 18 is controlled via the control unit 17 so that the film forming speed is maintained within a predetermined range. In the present embodiment, the predetermined range is set to 2 ° / s or more and 5 ° / s or less.

The electron beam source 18 also has a known configuration, and creates an electron beam EB that accelerates the thermoelectrons emitted from the filament at the anode and magnetically deflects them in a loop shape (not shown). , Evaporation material 23 is an electron beam
Heat and evaporate by EB irradiation.

Next, a method of forming an Au film according to the present invention using the electron beam evaporation apparatus having the above configuration will be described.

After setting the substrate W at a predetermined position in the vacuum chamber 15, the vacuum chamber 15 is evacuated to a degree of vacuum of about 10 ^-4 Pa. An Au ingot is put into the crucible 21 as the evaporation material 23, and the Au ingot 23
The electron beam EB is irradiated from the electron beam source 18 toward.

By the irradiation of the electron beam EB, the Au ingot 23 is heated and evaporated. At this time, the Mo liner member 24 interposed between the crucible 21 and the Au ingot 23, which is constantly cooled by the circulation of the cooling water, has a function of suppressing heat transfer from the Au ingot 23 to the crucible 21. As a result, the Au ingot 23 is kept warm in the crucible 21 and the output of the electron beam EB is stabilized,
It is possible to evaporate with a small electron beam output. A
The evaporated particles of the u ingot 23 adhere to and deposit on the substrate W.

At the same time, the film thickness of the substrate W is sequentially measured by the quartz oscillation type film thickness meter 16, and the film forming rate (deposition rate) is obtained by the control unit 17 so that the film forming rate becomes 2 ° / s or more and 5 ° / s or less. The output of the electron beam source 18 is controlled. The Au ingot 23 in the crucible 21 is evaporated while the electron beam output is kept low by such a function of reducing the film forming rate.

Therefore, according to the present embodiment, the vapor deposition is performed at a low rate of 5 ° / s or less while the liner member 24 is interposed between the crucible 21 and the evaporating material 23 to suppress the escape of heat required for evaporation. Since the process is performed, bumping of the Au ingot 23 as the evaporation material can be suppressed to prevent the evaporation particles from being coarsened, whereby a dense and uniform Au film can be formed on the substrate W. Become.

Further, according to the present embodiment, it is possible to suppress the occurrence of pinholes in the film due to the escape of coarse evaporated particles, and to obtain a flat film surface. Thus, it is possible to sufficiently cope with recent semiconductor designs under design rules on the order of submicrons without affecting the fabrication process.

In order to maintain a low film forming rate of 5 ° / s or less, it is required to control the film forming rate on the order of {circle around (1)}. Since the crystal oscillation type film thickness meter 16 is used, it is possible to more precisely control the film forming speed.

Further, according to the present embodiment, since the evaporation material 23 does not directly adhere to the crucible 21 by the liner member 24, the maintenance of the crucible 21 is simplified.

Although the embodiments of the present invention have been described above, the present invention is, of course, not limited thereto, and various modifications can be made based on the technical concept of the present invention.

For example, in the above embodiment, molybdenum (Mo), which is advantageous in terms of cost and quality, is adopted as the material of the liner member 24.
It is also possible to use a material such as carbon or carbon (C).

On the other hand, the evaporation material is not limited to gold (Au), but can be applied to other materials that are likely to cause bumping, such as copper (Cu) and aluminum (Al). In this case, it is necessary to select the liner member from a material that does not react with these evaporating materials during heating.

The liner member 24 is not limited to being formed separately from the crucible 21, but may be formed by forming a thick film of the material forming the liner member on the accommodating portion 22 of the crucible 21. You may make it implement integrally with the crucible 21.

[0025]

As described above, according to the electron beam evaporation method of the present invention, coarsening of evaporated particles due to bumping of the evaporated material can be suppressed, whereby a dense and uniform thin film can be formed. Can be.

According to the second aspect of the present invention, it is possible to accurately maintain and control a film forming rate as low as 5 ° / s or less. It is possible to reduce the influence on the processing, suppress the insulation failure and the wiring failure, and manufacture a semiconductor device excellent in quality.

[Brief description of the drawings]

FIG. 1 is an apparatus configuration diagram showing an outline of an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part in FIG.

FIG. 3 is a side sectional view of a liner member according to the present invention.

FIG. 4 is a sectional view showing an evaporation source of a conventional electron beam evaporation apparatus.

[Explanation of symbols]

15: vacuum chamber, 16: crystal oscillation type film thickness gauge, 18:
Electron beam source, 21 ... Crucible, 23 ... Evaporation material, 2
4 ... Liner member, EB ... Electron beam.

Claims (4)

[Claims] 1. An electron beam vapor deposition method for heating an evaporation material in a crucible with an electron beam to form a film on a substrate, wherein heat is transferred from the evaporation material to the crucible between the crucible and the evaporation material. An electron beam vapor deposition method, wherein a liner member for suppressing evaporation is interposed, and a deposition rate of the evaporation material is maintained at 5 ° / s or less to suppress an increase in the evaporation particle diameter of the evaporation material. 2. The electron beam evaporation method according to claim 1, wherein the control of the film forming speed is performed based on an output of a quartz oscillation type film thickness meter. 3. The electron beam evaporation method according to claim 1, wherein the evaporation material is gold, and the liner member is made of molybdenum. 4. The method according to claim 1, wherein the substrate is a semiconductor substrate.