JPS586972A - Hearth liner for vacuum deposition by electron beam - Google Patents

Abstract

PURPOSE:To provide a titled hearth liner which prevents the creeping of a source for vapor deposition out from the hearth liner and leaking to the rear side, minimizes the heat transfer between said source and a crucible and has improved vapor deposition efficiency by projecting eaves to the outside edge in the opening part of the hearth liner. CONSTITUTION:Eaves 1d are projected to the outside edge in the opening part of a bowl-like hearth liner 1 made of BN and TiB2, and the liner 1 is mounted by bringing the eaves 1d in contact with a crucible 3. Therefore, in spite of creeping of a metallic source 2 for vapor deposition melted in the liner 1 to the outside along the inside surface 1a of the liner 1, the creeping thereof out to the rear side 1c is prevented by the contact part T between the eaves 1d and the crucible 3, whereby the degree of the joining between the source 2 and the crucible 3 is minimized. Therefore, the heat transfer from the source 2 to the crucible 3 is minimized, and the efficient vapor deposition is performed from the liner 1 even with low input electron beams.

Description

DETAILED DESCRIPTION OF THE INVENTION In electron beam vacuum evaporation, when a metal source is heated to a high temperature and evaporated, the present invention is capable of lowering the input of the electron beam by interposing it between the metal source and the vacuum evaporation crucible. Hearth liner used for the purpose of increasing evaporation efficiency for vapor deposition
It is related to.

As the semiconductor industry has developed, techniques for coating semiconductor wafers with thin metal films and finely processing them have become important, and vacuum evaporation has been developed as a method for forming thin films. In recent years, as elements have become more integrated and have higher frequencies, it is necessary to make patterns finer and to make the electrode structure of the element multilayered, and it is desired to form a metal thin film of better quality.

Electron beam vacuum evaporation is currently the most common evaporation method because it can form a thin film of a metal material with a high melting point and low vapor pressure. It is necessary to keep the input low and perform vapor deposition efficiently. The reason is as follows.

(1) Backscattered electrons from metal source and vacuum evaporation crucible,
It is necessary to minimize the influence of radiation such as secondary electrons on the semiconductor wafer surface.

(2) Suppress the temperature rise of the semiconductor wafer due to thermal radiation pressure from the crucible.

(3) Avoid contamination of foreign matter from around the crucible.

Hearth liner 1 is used to keep the input of the electron beam low and increase the deposition rate to increase the deposition efficiency, and is made of a conductive material with very poor thermal conductivity.
Its structure is like a pot (see Figure 1). Conventionally,
Evaporation efficiency has been improved by using hearth liners made of materials such as tantalum, tungsten, and molybdenum, but these materials tend to react with the deposited metal and form alloys at high temperatures, so the materials used as the hearth liner may not be present in the formed metal thin film. It had the disadvantage of being included.

On the other hand, boron nitride (BN) and titanium boride (TiB)
) in the hearth liner 1 made of material, since a reaction between the deposited substance and the hearth liner material is unlikely to occur, contamination of foreign matter into the formed metal thin film can be avoided. However, even when using the hearth liner 1, the metal north 2
Depending on the type of the metal source 2, the metal source 2 can wet the hearth liner 1 very well. 6, it gets into the back side 1c of the hearth liner 1 (second
(see figure).

Therefore, the metal source 1 and the crucible 6 are connected to the hearth liner.
Since the entire back surface 1c is in contact with each other, heat conduction between the two is improved, and the vapor deposition efficiency is reduced, making the use of the hearth liner ineffective.

The present invention solves the above-mentioned problems and is characterized in that an eave is provided protruding from the outer edge of the opening of the bowl-shaped hearth liner.

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

In FIG. 3, in a pot-shaped hearth liner made of boron nitride (BN) and titanium diboride (TiB), an eaves 1d is provided protruding from the outer edge of the opening of the hearth liner 1. The hearth liner 1 is mounted on the crucible 6 with its eaves 1d in contact with the crucible 3. Even if the metal source 2 for evaporation melted inside the hearth liner 1 flows through the inner surface 1a of the hearth liner 1 and leaks out, the contact portion between the eaves 1d of the hearth liner 1 and the crucible 6...l its back surface. Since leakage to the 1C side is prevented and the degree of contact between the metal source 2 and the crucible 3 is minimized, heat conduction from the metal source 2 for deposition to the crucible 6 can be minimized.

Moreover, this hearth liner 1 allows efficient vapor deposition even with a low input electron beam.

Next, in order to demonstrate the actual effects of the present invention, a case will be described in which 2 cc of aluminum is used as a vapor deposition source. Table 1 shows 2 cc of aluminum with a purity of 9999%.
The graph shows the evaporation efficiency when evaporation is performed using the following three types of electron beam evaporation methods. - (1)! When aluminum is placed directly into a bowl-shaped crucible for electron beam evaporation (the material is oxygen-free copper).

(2) Boron nitride (BN) and titanium diboride (TIN3)
When using a conventional hearth liner with a thickness of 5m1jr made from 2).

(3) When the hearth liner according to the present invention is used, in which the opening edge of the hearth liner used in (2) is shaped like an eave.

As shown in FIG. 6, the dimensions of the crucible for electron beam evaporation are as follows: depth d is 10 mm, bottom surface diameter is 9 mm, D□ is 12 mm, and opening edge diameter is 60 mm. Further, the deposition conditions were all such that the ultimate vacuum level was 2×10'-7 om or less (the vacuum level in the Pelger evaporator), and the electron beam acceleration voltage was dα. Table 1 compares the values of the electron beam emission current required to obtain a deposition rate of 50 OA'/sec at a distance of 360 degrees from the deposition north.

As shown in Table 1, when the liner of the present invention is used, the current required to obtain a deposition rate of 300 A/sec is the same as that without the hearth liner as shown in (1). 45%, and 55% when using the conventional hearth liner (2), making it possible to significantly reduce the electron beam input current.

As described above, in the present invention, since the eaves are provided protruding from the outer edge of the opening of the hearth liner, it is possible to prevent the deposition source leaking out from the hearth liner to the back side of the hearth liner.
Since the degree of contact between the deposition source and the crucible is minimized, heat conduction between the two can be minimized and deposition efficiency can be increased. Furthermore, since heat conduction between the deposition source and the crucible is minimized, deposition can be performed efficiently even with a low input electron beam.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional hearth liner, FIG. 2 is a cross-sectional view showing a vapor deposition state using the conventional hearth liner, and FIG. 3 is a cross-sectional view showing an embodiment of the present invention. 1... Bar liner 1b... Opening edge of hearth liner 1d... Eave

Claims (1)

[Claims] (1) Bowl-shaped electron beam vacuum evaporation using boron nitride and titanium diboride as materials - Characteristic feature of the liner is that an eave is provided protruding from the outer edge of the opening of the 4-pot shaped hearth liner. Hearth liner for electron beam vacuum evaporation.