CN109072413B

CN109072413B - Metal evaporation material

Info

Publication number: CN109072413B
Application number: CN201780027018.2A
Authority: CN
Inventors: 仓内利春
Original assignee: Ulvac Inc
Current assignee: Ulvac Inc
Priority date: 2016-05-18
Filing date: 2017-05-12
Publication date: 2020-07-14
Anticipated expiration: 2037-05-12
Also published as: JPWO2017199873A1; JP6697073B2; CN109072413A; TW201812031A; KR20180130546A; WO2017199873A1; TWI673373B; KR102174869B1

Abstract

Provided is a metal evaporation material capable of preventing the generation of spatters without reducing the purity of a thin film. A metal evaporation material comprising a metal material having a metal as a base material and an additive metal, wherein the additive metal has 1/10000 metal low vapor pressure properties that have a vapor pressure lower than that of the base material at the same temperature at a temperature of 700 ℃ or higher, and reactivity with a gas released from a high-melting-point metal container to form a reaction product having 1/10000 product low vapor pressure properties that have a vapor pressure lower than that of the base material at the same temperature at a temperature of 700 ℃ or higher. Since the gas contained in the metal evaporation material reacts with the additive metal and is removed, bumping is prevented, and the content of the vapor of the additive metal and the vapor of the reaction product in the vapor of the metal evaporation material is less than 1/10000, so that the purity of the thin film formed by vapor deposition is not lowered.

Description

Metal evaporation material

Technical Field

The present invention relates to an evaporation material used for vacuum deposition of Au.

Background

Generally, the Au deposited film is produced by EB deposition using an electron beam evaporation source or resistance heating deposition using a W boat.

In the EB vapor deposition method, there are a method of heating and evaporating an Au evaporation material by directly charging the Au evaporation material into a water-cooled copper hearth (hearth), and a method of heating and evaporating an Au evaporation material by charging the Au evaporation material into a hearth lining (hearth liner) using a hearth lining made of W or Mo.

By using the hearth lining, the power consumption for evaporating Au can be greatly reduced, and Au does not adhere to the inside of the water-cooled copper hearth, so that maintenance of the evaporation source becomes easy.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2010-210681.

Disclosure of Invention

Problems to be solved by the invention

In order to form a hearth lining from a high-melting metal such as W, Mo, a powder of the high-melting metal is used as a raw material, and the raw material is sintered and molded into a container shape. Therefore, oxides derived from W powder and Mo powder are mixed as impurities in the hearth lining. Then, since the oxides (impurities) contained on the surface and inside of the hearth lining of the sintered body of W, Mo are heated to a high temperature at the time of Au deposition, the oxides are evaporated and dissociated to form a source of gas at the time of Au deposition. In particular, the impurities contained in the hearth lining cannot be consumed in a short time even if the hearth lining is heated and degassed.

The Au evaporation material contains dissolved gas taken in during melting in the atmosphere, lubricant and organic components involved in the material during drawing, and these impurities form a gas generation source during Au deposition. However, since they can be exhausted in a short time by degassing, in an actual deposition step, gas released from a hearth lining during Au deposition is mixed into a melt of Au, and the gas is subjected to bumping, so that droplets (splashes) of Au are released to the surroundings.

If these splashes adhere across the wirings of the circuit formed on the substrate, short circuits occur between the wirings, and thus a serious problem is caused in the step of forming the wiring circuit.

The present invention has been made to solve the above-described drawbacks of the prior art, and an object of the present invention is to provide a metal evaporation material that does not generate spatters during vapor deposition.

Means for solving the problems

In order to solve the above problems, the present invention is a metal evaporation material comprising a metal material having a base material of a predetermined metal or metals and an additive metal added to the metal material, wherein the additive metal has a metal low vapor pressure property of 1/10000 having a vapor pressure lower than that of the base material at the same temperature at a temperature of 700 ℃ or higher and a reactivity with a gas contained in the metal evaporation material to form a reaction product, and the reaction product has a product low vapor pressure property of 1/10000 having a vapor pressure lower than that of the base material at the same temperature at a temperature of 700 ℃ or higher.

Further, the present invention is a metal evaporation material, wherein the metal evaporation material is placed in contact with a high-melting-point metal container made of a high-melting-point metal and melted.

The present invention is a metal evaporation material, wherein the gas released from the high melting point metal contains oxygen, and the reaction product is an oxide of the additive metal.

The present invention is a metal evaporation material, wherein the high melting point metal is either W or Mo, and the metal of the base material of the metal evaporation material is Au containing impurities in a range of less than 0.01 wt%.

The present invention is the metal evaporation material, wherein the additive metal contains at least one or more of metal elements of Ta, Zr, Hf, or Nb.

The spatter is generated by the bumping phenomenon, which can be considered as: the gas released from the hearth lining dissolves in the molten Au in contact with the hearth lining, and the dissolved gas is collected and released to the outside of the melt.

If an additive metal capable of reacting with a gas emitted from a hearth lining to generate a reaction product having a lower vapor pressure than the base metal can be contained in a metal material containing the base metal as a main component, the gas contained in the metal evaporation material can be reduced, and therefore, bumping can be prevented.

Further, if the vapor pressure of the added metal is lower than 1/10000 at the same temperature as that of the base material as compared with the base material, and if 1/10000, which is a reaction product formed from the gas emitted from the hearth lining and has a vapor pressure lower than that of the base material at the same temperature as that of the base material, is also used as compared with the base material, bumping can be prevented without reducing the purity of the thin film formed by evaporating the metal evaporation material.

Effects of the invention

Bumping can be prevented without lowering the purity of a thin film of a base material formed by vapor deposition.

Drawings

Fig. 1 shows an example of a vapor deposition apparatus using a metal evaporation material of the present invention.

FIG. 2 shows Au, W and WO₂、WO₃A vapor pressure curve of the temperature versus vapor pressure of (a).

FIG. 3 is a vapor pressure curve showing the relationship between the temperature and the vapor pressure of Au, Ti, Hf, Zr, and Ta.

FIG. 4 shows Au, TiO and TiO₂、ZrO₂、HfO₂、Ta₂O₅A vapor pressure curve of the temperature versus vapor pressure of (a).

Detailed Description

The vapor deposition device 11 shown in fig. 1 includes a vacuum chamber 12, and a vapor deposition source 20 is disposed inside the vacuum chamber 12.

Above the vapor deposition source 20, the substrate stage 13 is disposed, and one or a plurality of substrates 14 are disposed on a portion of the substrate stage 13 facing the vapor deposition source 20. Here, the substrate stage 13 is a curved disk, and a plurality of substrates 14 are arranged with concave portions thereof facing the vapor deposition source 20.

The vapor deposition source 20 includes a copper container body (copper hearth) 21 having a recess formed therein, and a refractory metal container (hearth liner) 22 disposed in the recess of the container body 21 and made of a refractory metal.

Inside the refractory metal container 22, a metal evaporation material 23 is disposed.

A vacuum exhaust device 15 and a heating power source 17 are disposed outside the vacuum chamber 12, and an electron beam irradiation device 16 is disposed inside the vacuum chamber 12.

In the case of vapor deposition, the vacuum evacuation device 15 is operated to evacuate the inside of the vacuum chamber 12, and after a vacuum atmosphere is formed in the inside of the vacuum chamber 12, the heating power supply 17 is activated to supply electric power to the electron beam irradiation device 16, and the electron beam irradiation device 16 emits an electron beam. The released electron beam is irradiated to the metal evaporation material 23, and the metal evaporation material 23 is heated and melted to start evaporation of the metal evaporation material 23.

When the evaporation is stabilized, the shutter 26 is opened to allow the vapor to reach the surface of the substrate 14 placed on the substrate stage 13, and a thin film is grown on the surface of the substrate 14. When a thin film is grown, the substrate stage 13 is rotated by the motor 25, and the thin film is uniformly grown on the surface of each substrate 14.

Here, the metal evaporation material 23 is disposed inside the high melting point metal container 22 whose surface is exposed, and the melt of the metal evaporation material 23 is in contact with the exposed surface of the high melting point metal container 22.

The metal evaporation material 23 has a base material, which is a main component of a predetermined metal or a plurality of predetermined metals, and includes a metal material containing a trace amount of impurities in the base material and an additive metal added to the metal material, wherein the impurity content of the metal material is less than 0.01wt%, and the base material is contained in the metal material at 99.99wt% or more.

Since the additive metal has 1/10000 low vapor pressure property having a vapor pressure lower than that of the base material at the same temperature at 700 ℃ or higher, 1/10000, which is lower in the content of the vapor of the additive metal than that of the vapor of the base material, can be added to the vapor released from the melt of the metal evaporation material 23 when the metal evaporation material 23 is heated and melted, and a thin film of high purity formed from the base material can be formed on the surface of the substrate 14.

Since the base material of the metal evaporation material 23 is a metal that does not melt W or Mo constituting the high-melting-point metal container 22, the high-melting-point metal constituting the high-melting-point metal container 22 does not melt in the melt of the metal evaporation material 23, but if gas is released from the high-melting-point metal container 22 heated to a high temperature, the gas is mixed into the melt of the metal evaporation material 23.

Since the additive metal contained in the metal evaporation material 23 has a property (reactivity) of reacting with the gas released from the metal evaporation material 23 to generate a reaction product, the gas released from the high-melting-point metal container 22 and mixed into the melt of the metal evaporation material 23 reacts with the additive metal in the melt of the metal evaporation material 23 to generate the reaction product in the melt of the metal evaporation material 23.

At a temperature of 700 ℃ or higher, the reaction product has a low vapor pressure property, i.e., the vapor pressure is lower than 1/10000 which is the vapor pressure of the parent material at the same temperature as the temperature of the reaction product.

Therefore, the content of the vapor of the reaction product in the vapor generated from the melt of the metal evaporation material 23 is lower than 1/10000 of the vapor of the base material, and therefore the reaction product reaching the surface of the substrate 14 is small, and a thin film of the base material with high purity is obtained.

FIG. 2 shows Au, a high-melting metal W, and an oxide WO of the high-melting metal W as base materials₂、WO₃Graph of the relationship between temperature and vapor pressure. From this figure, WO₃Has a vapor pressure greater than that of Au, WO₂Since the vapor pressure of (2) is close to that of Au, it is obvious that WO is contained in the melt of the Au base material₂、WO₃In this figure and the figures described later, "1. E + n" represented by the numerical value of n represents 1.0 × 10ⁿ"1. E-n" means 1.0 × 10^-n。

Fig. 3 is a graph showing the relationship between the temperature and the vapor pressure of Au as the base material and Ti, Hf, Zr, and Ta as metals having high reactivity. However, among these metals, metal Ti has a vapor pressure close to the vapor pressure of the base material Au compared with Hf, Zr, and Ta which are additive metals, and therefore, when melting the metal evaporation material 23 containing Ti to generate vapor, Ti vapor is contained in the vapor at a high concentration, and thus it is not suitable to use Ti as the additive metal.

FIG. 4 shows Au, TiO oxides as base materials₂、ZrO₂、HfO₂、Ta₂O₅Graph of the relationship between temperature and vapor pressure. Obviously Ti oxides (TiO ) in the Au vapor₂) ZrO as an oxide of the added metal although the content of (2) is large₂、HfO₂、Ta₂O₅Since the content of (2) is small, it is found that Zr, Hf and Ta are suitable as the additive metals.

Examples

An Au ingot having a purity of 99.999% (5N) was melted in a vacuum atmosphere and degassed to obtain a 5N Au metal material. And adding metal into the metal material by changing the content ratio to obtain the metal evaporation material. Further, a metal evaporation material made of the metal material was obtained without adding an additive metal.

These metal evaporation materials were placed in the vapor deposition device 11 of fig. 1, and evaporated by heating, and an Au thin film having a thickness of 250nm was formed on the surface of the substrate 14 formed of a Si wafer having a diameter of 4 inches (4 inches in diameter) with the film formation rate changed. In the vapor deposition of the metal evaporation material, the film formation rate is measured by the film thickness monitor 31 and the control device 32, and the output of the electron beam irradiation device 16 is automatically controlled so that the film formation rate becomes constant.

Table 1 below shows vapor deposition conditions for vapor deposition by adding a metal evaporation material to which no metal additive is added to a W-made refractory metal container (hearth lining) 22.

Further, the metal evaporation material 23 was prepared by adding 2.5wt% of Ta as an additive metal to a metal material, and the deposition conditions when the metal evaporation material 23 was charged into a W-made high melting point metal container 22 and deposited were shown in table 2 below, and the deposition conditions when the container body 21 made of copper was directly charged and deposited were shown in table 3 below.

In addition to Ta, Zr, Hf and Nb have extremely low vapor pressure as compared with Au, are active against various types of off-gases, and have low vapor pressure properties of metals and low vapor pressure properties of products, so Zr, Hf and Nb also have the same effect of reducing spatters as Ta.

[ TABLE 1 ]

。

[ TABLE 2 ]

。

[ TABLE 3 ]

。

After the formation of the Au thin film, the number of particles having a particle diameter of 0.2 μm to 1.5 μm attached was measured as the number of splashes attached (the number of foreign matter attached).

When the refractory metal container 22 is not disposed in the container main body 21 and the metal evaporation material 23 is disposed in contact with copper exposed on the surface of the container main body 21, the measurement results when an additive metal composed of Ta is used are shown in table 4 below, and the measurement results when an additive metal composed of Zr is used are shown in table 5 below.

When the refractory metal vessel 22 made of W is placed in the vessel body 21 and the metal evaporation material 23 is placed in contact with the surface of the refractory metal vessel 22 in the refractory metal vessel 22 and melted, the measurement results when the additive metal composed of Ta is used are shown in table 6 below, and the measurement results when the additive metal composed of Zr is used are shown in table 7.

[ TABLE 4 ]

。

[ TABLE 5 ]

。

[ TABLE 6 ]

。

[ TABLE 7 ]

。

From the measurement results shown in tables 4 and 5, it is understood that the number of adhering splashes is greatly reduced by adding 0.1wt% or more of the additive metal.

In particular, in the case of the metal evaporation material 23 to which the metal additive was added in an amount of 2.5wt%, the number of adhering splashes (foreign matters) was reduced to about 1/13, as compared with the metal evaporation material made of the Au base material to which vacuum melting was performed but the metal additive was not added.

The content of the added metal was not significantly changed within the range of 2.5 to 10wt%, and good results were obtained in any case.

Since the gas is released from the high-melting-point metal container 22, the number of splashes deposited increases in the case where the metal evaporation material 23 is disposed in the high-melting-point metal container 22 and vapor-deposited as compared with the case where the metal evaporation material 23 is directly disposed in the container main body 21 and vapor-deposited.

However, in table 6, the number of splashes adhered can be reduced to about 1/3 by adding 0.1wt% or more of Ta to the Au base material, as compared with a metal evaporation material made of an Au base material that was vacuum-melted without adding an additive metal.

Further, by increasing the amount of Ta added to Au to 2.5wt%, the number of splashes deposited was greatly reduced, and it was possible to reduce the amount to 1/25, as compared with a metal evaporation material made of an Au base material in which vacuum melting was performed but no additional metal was added.

The content of Ta was not significantly changed within the range of 2.5 to 10wt%, and good results were obtained in any of the contents.

Further, according to table 7, even when Zr is contained as an additive metal in the Au base material, the effect of reducing the number of adhering splashes is found to be the same as that when Ta is contained as an additive metal.

Table 8 below shows the number of splashes when the metal evaporation material containing Ti as an additive metal was placed in the W-made refractory metal container 22 and melted. The number of splashes was smaller in the case of Ti than in the case of Ta and Zr, but as shown in table 9, the resistivity of the Au thin film obtained from the metal evaporation material containing Ti as an additive metal was higher than that of the Au thin film obtained from the metal evaporation material formed from the Au base material not added, and therefore it is considered that Ti was contained in a high concentration in the Au thin film. In the metal evaporation material 23 containing Ta and Zr as the additive metal, the resistivity is a value similar to that of the Au thin film obtained from the metal evaporation material formed of the Au base material not added, and it is understood that the additive metal is not contained in the Au thin film.

[ TABLE 8 ]

。

[ TABLE 9 ]

。

In the above, Au is used as the base material, but when the base material is another metal, the present invention can be applied to a metal evaporation material of a metal other than Au as long as W, Mo is not melted and an additional metal having a low vapor pressure property of the metal and a low vapor pressure property of the product is added to the metal evaporation material.

The base material is not limited to a single metal, and may be an alloy.

Description of the reference numerals

23 … … Metal Evaporation Material

22 … … refractory metal container.

Claims

1. A metal evaporation material having a metal material with Au as a base material containing impurities in a range of less than 0.01wt%, and

an additive metal added to the metal material, characterized in that,

the additive metal has:

1/10000 metal low vapor pressure property having a vapor pressure lower than that of the base material at the same temperature at 700 ℃ or higher, and

reactivity to react with a gas contained in the metal evaporation material to form a reaction product,

the reaction product has a product low vapor pressure property of 1/10000 having a vapor pressure lower than that of the parent material at the same temperature at a temperature of 700 ℃ or higher,

the additive metal contains at least one or more of metal elements of Ta, Zr, Hf, or Nb.

2. The metal evaporation material of claim 1, wherein the metal evaporation material is disposed in contact with a refractory metal vessel formed of a refractory metal and melted.

3. The metal evaporation material of claim 2, wherein the gas released from the refractory metal contains oxygen, and the reaction product is an oxide of the additive metal.

4. The metal evaporation material of any one of claims 2 or 3, wherein the refractory metal is any one of W and Mo.