JPS61575A - Continuous vapor deposition method of aluminum - Google Patents

Abstract

PURPOSE:To deposit continuously Al by a vacuum deposition method with high thermal efficiency by using a conductive ceramic boat of which the surface in the bottom of the inside cavity is roughened as a boat for evaporation of the Al in the stage of said continuous vapor deposition. CONSTITUTION:The boat consisting of the conductive ceramics consisting essentially of conductive TiB2 and contg. BN and AlN having an insulating characteristic is used as the boat 1 for evaporation of the Al for vapor deposition to be used in the stage of depositing the Al by a vacuum deposition method of the surface of the long-sized substrate. The base surface 3 of the cavity 2 of said boat 1 in which the Al is to be incorporated is roughened. The Al is put into the cavity 2 of the boat 1 and electricity is conducted to the boat 1 to generate heat thereby melting and evaporating the Al therein. The roughened base surface of the boat 1 contributes to an improvement in the wet spreading of the molten Al and heat transmission. The continuous vapor deposition of the Al with high thermal efficiency is thus made possible.

Description

Detailed Description of the Invention [Industrial Application Field J] The present invention relates to a continuous vacuum evaporation method of aluminum (AI), in particular, to a resistance heater (hereinafter referred to as a port) for evaporation made of a specific conductive ceramic, and to This invention relates to a continuous vapor deposition method of AI!, in which AI! is evaporated while being supplied to a cavity, and then deposited on a substrate.

[Prior Art and Problems] Various methods have been proposed for vacuum-depositing metal onto a base material, but all of them are patch-type methods.

For example, AI in MO5 field effect transistor! A method of using a mixed sintered body of holon nitride (BN), which has excellent insulation, corrosion resistance, and wettability with A1, and titanium polide (TiB2), which has excellent conductivity and corrosion resistance, in the port when vacuum evaporating. There is.

To explain further, this involves putting the required amount of Aj) into the cavity of the port, energizing it, melting AI, forming a pool, and AI! This method involves evaporating and depositing. However, in such a port, even if a large amount of AP is filled and melted and evaporated, AI! Due to poor wetting with AR, islands of AI remain at the end of AR evaporation, slowing down the evaporation rate, and making the film uneven. Close the shutter to prevent uneven film thickness. However, it is necessary to adjust the power supply, and AP cannot be deposited on a long base material. (Japanese Unexamined Patent Publication No. 51-74574) In addition, silver is evaporated using a port made of high-melting 8-point metal such as tantalum (Ta) or tungsten (W) with an uneven surface on the bottom surface of the cavity. There is a method of vapor deposition.

However, since this uses Ta or W as the port material, its corrosion resistance is poor and AI! It cannot be used for vapor deposition. Furthermore, since this is a method in which Ag is batch-deposited onto a base material, as with the above method, Ag remains in the form of islands at the end of the deposition, so an uneven surface is provided on the bottom of the cavity to reduce the amount of remaining Ag. It is not a continuous deposition method.

(Utility Model Application Publication No. 50-40850) As mentioned above, in the conventional batch vapor deposition method, for example, Al
It has been difficult to continuously supply a vapor deposition material to a conductive ceramic port and form a uniform vapor deposition film of Ail on a long base material.

The present inventors believe that the important things when depositing All on a long substrate are the composition and shape of the material of the ceramic port that evaporates AR, and the means of operation. conducted research.

In general, ports made of ceramics are slightly less wetted by molten vapor deposition material than ports made of high-melting point metals, so contact between the port and the vapor deposition material is insufficient, and the heat generated by the port does not reach the vapor deposition material sufficiently. The heat was dissipated as radiant heat, resulting in poor thermal efficiency.

Furthermore, the vapor deposition material spreads poorly into the cavity, making it difficult to wet the entire bottom of the cavity with the molten vapor deposition material, and the entire bottom of the cavity cannot be effectively used as an evaporation area, so the amount of evaporation per unit time is low. I found out.

Usually, the wetting angle θ is used to measure the wettability between a solid surface and a molten metal.

COSθ=R(ys-yst)/yt,
R is a roughness factor, and γS, yst, and γF are surface tensions of the solid surface, solid-liquid interface, and liquid, respectively.

Here, R represents the true surface area relative to the apparent surface area. By increasing R, θ approaches O, and the solid surface becomes easier to wet with molten metal.

Furthermore, if the surface is made rough to increase the surface area, the molten metal will wet and spread thinly and widely on the inner bottom of the cavity, and the area will always be constant.

Also, as a means of operation, AI! It is necessary to continuously supply molten AP to the port cavity so that the molten AP spreads uniformly over the entire bottom surface of the cavity and to increase the evaporation rate, so the inside bottom surface of the cavity must be roughened so that the current can flow through the cavity evenly. The present invention was completed based on the knowledge that it is sufficient to do so.

[Means for Solving the Problems] The present invention is a method for continuously vapor depositing aluminum on a substrate using a vacuum evaporation device. A resistance heater is provided in the vacuum deposition apparatus, and the heater is energized to continuously supply aluminum into the cavity, spread it uniformly, and operate with little fluctuation in current or voltage. This is a method of continuously vapor depositing aluminum on a base material.

The present invention will be explained in more detail below.

The drawing shows an embodiment of the present invention in which the inner bottom surface 3 of the cavity 2 of the port 1 is provided with a rough surface.

The port used in the present invention is mainly made of conductive TiB2 with a rough inner bottom surface of the cavity, and is made of insulating ON
and Ai'N.

The hardness of the port material components of the present invention is 9, 7, and 2 respectively for TiB2, AlN, and BN, so when the rough surface is formed, B) l is mainly removed, so that the conductivity of the surface of the inner bottom of the cavity is reduced throughout the port. It is thought that the current flow is different from that of the entire port.

Further, since the wetting of the molten Af and the port is very subtle and varies depending on the material used and the deposition temperature, the effect of making the surface rough as described above is great.

In continuous AR deposition, a uniform Ap deposition film cannot be formed unless the melt of Ai) spreads uniformly and the AP is constantly evaporated. The reason why a sintered body containing TiB2 as a main component and BN and ApN is used as a port material is because a sintered body of TiB2 and BN has insufficient corrosion resistance, strength, density, and wettability. It is.

In the continuous AN method of the present invention, Al1 must be evaporated from the entire surface of the cavity at a constant rate while adding a constant amount of molten AP to the cavity. Therefore, it is necessary to make the inner bottom surface of the cavity rough so that the flowing current passes through the inner bottom layer of the cavity of Bonito and increase the evaporation rate, and to make the melt layer of Ap thinner to improve wetting with Aj). There is.

Furthermore, in continuous evaporation of Ap, evaporation is performed in a steady state with a constant amount of molten A2 maintained in the cavity;
In this steady state, the upper part is filled with the molten Af layer, the lower part is the conductive ceramic layer of the port body, and the middle part is filled with AP obtained by heating and melting the rough inner bottom surface of the cavity, and the conductive ceramic and molten AI! Because the resistance value decreases stepwise from the bottom to the top to form a three-layer structure with a boundary layer composed of The temperature gradient between the layer and the high-temperature port body, which is the heat supply source, is maintained in a graded manner due to the existence of a boundary layer between the rough surface of the intermediate ceramic and the molten Ap, and the heat conduction increases while relaxing the temperature gradient. At the same time, melting AI! acts synergistically to wet the skin.

Next, the method of making the inner bottom surface of the cavity rough so that it is easily wetted by the vapor deposition material is (1) Spraying an abrasive material made of SiC or the like using a sandblasting device or the like onto the bottom surface of the cavity of the port processed from a conductive ceramic material. (2) A method of forming a rough surface that is sufficiently wettable by the vapor deposition material by polishing the bottom surface of the cavity with a polishing rotary grindstone made of SiC, diamond, etc. , (3) In the step of forming a cavity in the port after external processing, there are three methods: forming the cavity by grinding using a rotary grindstone with coarse diamond on the grinding surface.

In particular, method (3) allows A
I! There is an advantage that a port having a cavity inner bottom surface that is easily wetted by the vapor deposition material can be obtained.

Next, to explain the vapor deposition method U) of the present invention, the above-mentioned port is provided in a vacuum evaporator, and
-4Torr or more) energize the port and continuously Ajl!
It is evaporated while being dropped into the cavity as a melt from a wire, and is deposited while moving on a long substrate.

In this way, the AP deposition film can be uniformly deposited on the surface of the long base material.

According to the present invention, melted AI! Since the wetting and spreading area does not change over the entire surface of the inner bottom of the cavity, there is no change in the resistance of the port, making it easy to control the power supply during deposition. Furthermore, the amount of heat transferred increases, allowing efficient deposition with less power than conventional ports.

Furthermore, the vapor deposition material Ai) is deposited from the entire surface of the inner bottom of the cavity.
can be evaporated, operation can be performed at lower port temperatures, and the amount of Ai) deposited per unit time can be increased. More ports and AI! There is no reaction with the evaporation material, no local corrosion is observed, and the life of the port is extended.

[Example] Next, the present invention will be explained according to comparative examples and examples.

Comparative Example 1 Specific resistance is 1200. A conductive ceramic containing 48 parts by weight of titanium polide as a conductive component, 28 parts by weight of poron nitride as an insulating component, and 24 parts by weight of aluminum nitride as an insulating component was molded by hot pressing so as to have Ω-C■.

18X 8X10 from this conductive ceramic molded body
Cut out a 0mm port and cut it with 250 mesh diamond foil, width 12mm, depth 1.5m
+a, a cavity with a length of 7 hm was formed.

An Al wire with a diameter of 1.5 square meters was selected as the vapor deposition material, and continuous vapor deposition was performed on the original plastic film from a port heated by direct electricity using a continuous supply device.

The deposition was carried out at a voltage of 8.5 V and a current of 350 A. The amount of AR evaporated per unit time was 1.5 g/min.

The molten Aff does not spread all over the cavity,
Wetness spread only to about half of the wall along one side of the cavity, and even if we further increased the voltage and port temperature, the wetting and spreading did not improve. After 300 minutes of evaporation under these conditions, the port reacted with the evaporation material on the wall of the cavity, and the port became deformed and could not withstand further evaporation.

Example 1 A cavity was formed in the port under the same conditions as Comparative Example 1.

A 60-mesh layer of Si was applied to the bottom of the resulting port cavity using a sandblasting device at an air pressure of 5 Kg/cm2.
C abrasive was sprayed for 10 seconds to create a port with a rough inner bottom surface of the cavity.

Using this port, Aj) was continuously deposited by the method shown in Comparative Example.

Vapor deposition was performed at a voltage of 8. AI performed with OV current of 310A! The amount of evaporation per unit time was 1.8 g/min.

The molten AP wetted and spread over the entire bottom surface of the cavity, and no fluctuations in voltage or current were observed.

Example 2 Using the same conductive ceramic molded body as Comparative Example 1, 16
A port measuring 8 x 100m+a was cut out using the conventional method, and a 12+sm width and 1.5m depth was cut using a rotary grindstone with 80 mesh diamonds on the polished surface.
A cavity with a rough bottom surface and a length of 70 nm was formed.

Using this port, AI! Continuous vapor deposition was carried out.

Vapor deposition was performed at a voltage of 8. The amount of evaporation per unit time of Aj) was 2.0 g/min when the OV current was 300 A. Melted AI! Wetness spread over the entire surface of the inner bottom of the cavity, and no fluctuations in voltage and current were observed, allowing extremely stable operation. Continuous deposition was carried out for 300 minutes under these conditions, but no corrosion was observed on the inner wall of the cavity.

Comparative Example 2 A conductive ceramic made of 60 parts by weight of titanium polide and 40 parts by weight of poron nitride was molded by hot pressing so that the specific resistance was 1200-Ω-C11.

18X 8X100 from this conductive ceramic molded body
Cut out the +a+a port and cut it with 250 mesh diamond foil, width 12mm, depth 1.5
mm, length? A cavity of 0+am was formed.

AP wire with a diameter of 1.5 m+s was selected as the deposition material, and continuous deposition was performed from a port heated by direct energization using a continuous horse feeder.

Vapor deposition was performed at a voltage of 8.5V and a current of 350A using AI! The amount of evaporation per unit time was 1.5 g/min.

20 minutes after starting vapor deposition, the center of the port, which was held down at both ends, warped upward, and the molten AF did not wet and spread over the entire surface of the cavity, but spread around half along one wall of the cavity. Even if the voltage was increased further and the port temperature was raised, the wetting and spreading did not improve.

When vapor deposition was continued in this state, after 40 minutes, the cavity was AI! A hole was created near the point of fall, making it impossible to withstand further vapor deposition.

[Effects of the Invention] According to the present invention, by using a specific ceramic port, it has been difficult to continuously deposit AP.
It has the excellent effect of being able to obtain a uniform deposited film on the substrate with a simple operation.

[Brief explanation of drawings]

The drawings are schematic illustrations of embodiments of the invention. 1 is a resistance heater 2 is cavity 3 shows the bottom surface of the cavity.

Claims (1)

[Claims] 1) In a method of continuously vapor depositing aluminum on a substrate using a vacuum evaporation device, a resistance heater containing BN and AlN is provided in the vacuum evaporation device, the main component being TiB_2 with a roughened inner bottom surface of the cavity, A continuous vapor deposition method for aluminum, characterized in that the heater is energized to supply aluminum into the cavity, spread it uniformly, and operate in a state with little fluctuation in current or voltage.