JPH06299336A - Crucible of evaporating source for vacuum deposition - Google Patents

Abstract

PURPOSE:To uniformize the temp. distribution of a crucible, to stably feed molecular beads of a material without varying the amt. with the lapse of time, to suppress a remarkable temp. drop at the opening of the crucible and to improve the quality of a formed film. CONSTITUTION:The thickness of the upper part 11a and the lower part 11c of a crucible 11 is made larger than that of the middle part 11b. A heater 12 wound around the crucible 11 is divided into two and separately wound around the upper and lower parts of the crucible 11. The ratio of the number of winding at the upper part to that at the lower part is regulated to about 4:1. Since the upper and lower parts of the crucible 11 are thicker, the surface area of the inside of the crucible is reduced and the quantity of heat radiated is reduced. As a result, the temp. in the regions is raised and the temp. of the entire crucible is acceleratedly uniformized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an evaporation source for vacuum vapor deposition used in a thin film manufacturing apparatus such as a molecular beam epitaxy apparatus (MBE).

[0002]

2. Description of the Related Art In a conventional crucible used for a vacuum evaporation source, a crucible 1 has a constant thickness as shown in a sectional view of FIG. In the conventional evaporation source crucible for vacuum evaporation having such a constant thickness, the temperature at each portion is different during use, and the temperature uniformity in the entire crucible is poor. The temperature distribution is shown in FIG.

FIG. 6 is a temperature distribution chart showing the temperature in the vertical axis and the position in the longitudinal direction of the crucible in the horizontal axis. The temperature at the bottom (lower part) of the crucible and the temperature at the crucible opening (upper part) are shown in FIG. The temperature is low and the temperature in the middle is high, and the temperature difference between the high temperature and the low temperature in the actual use of the crucible is about 40 degrees.

[0004]

As described above, the conventional evaporation source crucible having a constant thickness has a large temperature difference between high temperature and low temperature in actual use. As a result, the following two phenomena occurred. That is, firstly, since the saturated vapor pressure of the vaporized material is very much dependent on temperature, the molecular dose vaporized from the evaporation source varies significantly with decreasing material. Secondly, in the existing crucible, the temperature drop at the crucible opening is remarkable, so that the evaporated material is solidified and deposited again near the crucible opening. Then, when the deposited material falls into the crucible, the bumping phenomenon occurs in which the melted material becomes particulate and jumps out.

The above-mentioned two points are the main causes of the problems that the improvement of the quality of the film formed by vapor deposition is hindered and the film is apt to have defects.

The present invention has been made in consideration of the above-mentioned problems of the prior art, and aims to make the temperature distribution of the crucible uniform,
Evaporation source for vacuum vapor deposition that enables stable supply of the molecular dose of the material with no temporal fluctuation and suppresses a significant temperature drop at the opening of the crucible to improve the quality of the deposited film. The purpose is to provide crucibles.

[0007]

In order to achieve the above object, the present invention provides a crucible in which a material to be vaporized by an evaporation source for vacuum vapor deposition is placed, and the thickness of the crucible can be set to the upper, middle and lower portions of the crucible. The feature is that the temperature distribution of the crucible is made uniform by changing each.

It is characterized in that the thickness of the crucible described above is made thicker in the upper and lower parts than in the middle part of the crucible, and the thickness of the crucible is made thicker in the lower region of the crucible. .

[0009]

When the evaporation source for vacuum vapor deposition is used in a high temperature range of 1000 ° C or higher, the heated crucible is a stephan-
It is known from the actual measurement of the temperature distribution and its numerical calculation simulation that heat is radiated according to Boltzmann's law and the effect thereof has a great influence on the temperature distribution of the crucible.

In the present invention, the thickness of the crucible is changed at the upper part, the middle part and the lower part respectively. In the case where the thickness is increased at the upper part and the lower part of the crucible as compared to the middle part, the inside of the crucible of the part is increased. Since the surface area will be reduced,
The amount of heat radiation above and below the crucible is reduced, so that the temperature in that region can be increased more than in the conventional case, and the temperature uniformity of the entire crucible can be promoted. This temperature distribution is clearly shown in FIG. 4 (present invention) similar to FIG. 6 (conventional example), and in actual use of the crucible, the temperature difference between the high and low hot water portions of the crucible is about It has been improved to 10 degrees and, as a result, the stability of the molecular dose of vaporized material is greatly increased.

Further, in the case where the thickness of the crucible is made thicker in the lower region, a material having a vaporizing action whose melting point is not so high is mainly used, so that the temperature of the opening is easily kept higher than the melting point of the material, and A uniform temperature is achieved in the lower region of the crucible.

[0012]

Embodiments of the present invention will now be described with reference to the drawings. FIG. 1 is a sectional view of a crucible showing an embodiment of the present invention, and FIG. 2 is a sectional view of an embodiment in which a heater for heating the crucible is wound.

In FIG. 1, the crucible 11 has an upper portion 11a.
The lower part 11c is thicker than the middle part 11b.

Further, in FIG. 2, the heater 12 wound around the crucible 11 is wound around the upper part 11a and the lower part 11c of the crucible 11 separately, and the heater 1 wound around the upper part 11a.
The ratio of the number of turns of 2 to the number of turns of the heater 12c wound around the lower portion 11c is about 4: 1. In addition, when the length of the crucible is 20 mm in the upper part a, 20 mm in the middle part b and 30 mm in the lower part, which is 70 mm in total, the number of turns of the heater wire 12 is 8 turns in the upper part 11 a and 2 turns in the lower part 11 c.
The crucible upper portion 11a and the lower portion 11c are wound at a pitch of 3 mm, the wall thickness d ₁ of the crucible upper portion 11a is 2 mm, and the middle portion 11b has a thickness d ₂ of 0.8 mm.
No. 2 starts to be wound as close as possible to the crucible collar 11d, and is wound at a lower part with a slight distance e = 3 mm from the bottom.

The temperature difference in the crucible when the crucible 11 configured as described above is in operation is shown in FIG. 4, which is similar to FIG. The longitudinal position of the crucible is located on the axis. According to this, the temperature difference in the crucible in the region where the material is put in the crucible is about 1
It has been improved to 0 degrees and the temperature difference of the conventional example (Fig. 6) is 40
The temperature can be about 1/3 or less of the temperature, and the temperature uniformity can be improved.

FIG. 3 is a sectional view of a crucible showing another embodiment of the present invention. This embodiment is a crucible using a material for an evaporation source whose melting point is not too high, and the crucible 21 is thick in the lower region 21b.

According to this embodiment, the temperature of the crucible opening 21a can be easily kept higher than the melting point of the material by using the material for the evaporation source whose melting point is not so high, and It is possible to make the temperature uniform in the region 21b below the crucible.

[0018]

As described above, according to the present invention,
The thickness of the evaporation source crucible for vacuum deposition is set to the upper part of the crucible,
The temperature distribution of the crucible can be made more uniform than that of the conventional one by changing the middle part and the lower part, and the evaporation source for vacuum deposition is a stable molecular dose source with little time fluctuation. Available as As a result, the quality of the deposited film can be improved.

In particular, by increasing the thickness of the crucible in the upper portion and the lower portion as compared with the middle portion, the temperature distribution can be made uniform over the entire length of the crucible, and the thickness of the crucible can be reduced in the lower region. By thickening with, it is possible to easily keep the temperature of the crucible opening higher than the melting point of the material and to make the temperature uniform in the lower region when using the material for the evaporation source whose melting point is not too high. .

[Brief description of drawings]

FIG. 1 is a sectional view of a crucible showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view in which a heater is wound around a crucible showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view of a crucible showing another embodiment of the present invention.

FIG. 4 is a temperature distribution diagram in the crucible of the present invention.

FIG. 5 is a sectional view of a crucible showing a conventional example.

FIG. 6 is a temperature distribution diagram in a conventional crucible.

[Explanation of symbols]

 11 crucible 11a upper part 11b middle part 11c lower part 11d collar 12 heater 21 crucible 21a opening 21b lower region

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toyoji Uchiyama 2500 Hagizono, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd.

Claims (3)

[Claims] 1. A crucible containing a material to be vaporized by an evaporation source for vacuum vapor deposition, characterized in that the thickness of the crucible is changed at each of the upper part, the middle part and the lower part of the crucible to make the temperature distribution of the crucible uniform. Crucible of evaporation source for vacuum evaporation. 2. The crucible as a vapor deposition source for vacuum vapor deposition according to claim 1, wherein the crucible has an upper portion and a lower portion that are thicker than the middle portion of the crucible. 3. A crucible as an evaporation source for vacuum vapor deposition according to claim 1, wherein the thickness of the crucible is increased in a region below the crucible.