TW201812031A - Metallic evaporation material - Google Patents

Abstract

Provided is a metal evaporation material with which it is possible to prevent splashing without lowering the purity of the thin film. A metal evaporation material having a metal material in which a metal is the parent member and an additive metal, wherein the additive metal has: a metal low vapor pressure property such that, at a temperature of at least 700 DEG C, the vapor pressure is less than 1/10,000th the vapor pressure of the parent material at the same temperature; and a reactivity such that the additive material reacts with gases released from a high-melting-point metal container to produce a reaction product. The reaction product has a product low vapor pressure property such that, at a temperature of at least 700 DEG C, the vapor pressure is less than 1/10,000th the vapor pressure of the parent material at the same temperature. Bumping is prevented because the gas contained in the metal evaporation material reacts with the additive metal and is eliminated. The purity of the vapor-deposited thin film does not decline because additive-metal vapor and reaction-product vapor constitute less than 1/10,000th of the metal evaporation material vapor.

Description

   Metal evaporation material   

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

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

In the EB evaporation method, there are a method of directly placing Au evaporation material in a water-cooled copper hearth for heating and evaporation, and using a hearth liner made of W or Mo. Au is built in the hearth liner. Method for heating evaporation of evaporation material.

By using the hearth liner, the power consumption for evaporation of Au can be greatly reduced. Since Au is not attached to the water-cooled copper hearth, maintenance of the evaporation source can be facilitated.

    Prior art literature         Patent literature    

Patent Document 1: Japanese Patent Application Laid-Open No. 2010-210681

In order to form a hearth pad from a high-melting metal such as W or Mo, a powder of the high-melting metal is used as a raw material, and is formed into a container shape by sintering. Therefore, oxides from W powder or Mo powder are mixed as impurities in the hearth liner. In addition, oxides (impurities) contained on the surface or inside of the hearth liner of these sintered bodies of W or Mo are heated at a high temperature during Au evaporation, and the oxides are evaporated or dissociated to become Source of gas during Au vapor deposition. In particular, the impurities contained in the hearth liner cannot be depleted in a short time even if the hearth liner is to be heated and degassed.

The Au evaporation material contains dissolved gas taken in when dissolved in the atmosphere or a lubricant or organic component drawn into the material during wire drawing. These impurities become a source of gas generation during Au vapor deposition. However, since they can be depleted in a short time by degassing, in the actual vapor deposition step, the gas system released from the hearth liner during Au vapor deposition is mixed into the melt of Au, and they The gas swells and releases droplets (spatters) of Au to the surroundings.

If these splashes are attached across the wiring spaces of the circuit formed on the substrate, the wiring spaces will be short-circuited, which is a big problem in the step of forming the wiring circuit.

The present invention was created by the inventor to solve the above-mentioned disadvantages of the conventional technology, and an object thereof is to provide a metal evaporation material which does not cause spattering during vapor deposition.

In order to solve the above problems, the present invention is a metal evaporation material, which is a metal material having a specified one or more kinds of metals as a base material and a metal-added metal evaporation material added to the foregoing metal material, which is characterized by: The aforementioned added metal has a low vapor pressure property of the metal at a temperature of 700 ° C. or higher, a vapor pressure of 1/10000 or less of the vapor pressure of the base material of the same temperature, and reacts with a gas contained in the metal evaporation material. The reactivity of the reaction product is generated; and the reaction product has a low vapor pressure of a product having a vapor pressure of 1/10000 or less of the vapor pressure of the base material at a temperature of 700 ° C. or higher and less than the vapor pressure of the base material.

In addition, the present invention is a metal evaporation material, and the metal evaporation material is a metal evaporation material which is arranged in contact with a high melting point metal container made of a high melting point metal and is melted.

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

The present invention is a metal evaporation material, and the metal of the base material of the metal material is a metal evaporation material of Au containing impurities in a range of not more than 0.01% by weight.

In the metal evaporation material of the present invention, the additive metal is a metal evaporation material composed of at least one of the above-mentioned metal elements among the metal elements of Ta, Zr, Hf, or Nb.

It is thought that the spattering occurs due to the bumping phenomenon. The gas emitted from the hearth gasket is dissolved in the molten Au in contact with the hearth gasket, and the dissolved gas is collected and released to the outside of the melt.

If it can react with the gas emitted from the hearth liner to produce a reaction product with a lower vapor pressure than the base material, and the metal is contained in the metal material containing the base material as the main component, the metal evaporation material can be reduced. The gas contained in it can prevent bumping.

In addition, if the added metal is compared with the base material at a vapor pressure of less than 1/10000 at the same temperature as the base material, and the reaction product with the gas emitted from the hearth liner is also compared with the base material, When the base material does not reach a vapor pressure of 1/10000 of the vapor pressure of the base material at the same temperature, the purity of the thin film formed by the evaporation of the metal evaporation material will not be reduced, and bumping will not occur.

It is possible to prevent bumping without reducing the purity of the thin film of the base material formed by evaporation.

23‧‧‧metal evaporation material

22‧‧‧High melting point metal container

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

Fig. 2 is a vapor pressure curve showing the relationship between the temperature and vapor pressure of Au, W, WO ₂ and WO ₃ .

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

FIG. 4 is a vapor pressure curve showing the relationship between the temperature and vapor pressure of Au, TiO, TiO ₂ , ZrO ₂ , HfO ₂ , Ta ₂ O ₅ .

    Implementation of the invention    

The vapor deposition apparatus 11 in FIG. 1 includes a vacuum tank 12, and a vapor deposition source 20 is disposed inside the vacuum tank 12.

A substrate holder 13 is disposed above the evaporation source 20, and one to a plurality of substrates 14 are disposed at a portion of the substrate holder 13 facing the evaporation source 20. Here, the substrate holder 13 is a curved disk, and a concave portion thereof faces the evaporation source 20, and a plurality of substrates 14 are arranged.

The vapor deposition source 20 includes a copper container body (copper hearth) 21 having a recessed portion, and a high-melting-point metal container (hearth liner) 22 made of a high-melting-point metal disposed in the recessed portion of the container body 21.

A metal evaporation material 23 is arranged inside the high-melting-point metal container 22.

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

When performing the vapor deposition, the vacuum exhaust device 15 is operated, and the inside of the exhaust vacuum tank 12 is directly emptied. After a vacuum environment is formed inside the vacuum tank 12, the heating power source 17 is started to supply power to the electron beam irradiation device 16, The electron beam is released from the electron beam irradiation device 16. The emitted electron beam is irradiated to the metal evaporation material 23, and the metal evaporation material 23 is heated and melted to start the evaporation of the metal evaporation material 23.

When the evaporation is stable, the shutter 26 is opened to allow the vapor to reach the surface of the substrate 14 that has been placed on the substrate holder 13, and the thin film is grown on the substrate. When the film is grown, the substrate holder 13 is rotated by the motor 25 to uniformly grow the film on the surface of each substrate 14.

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

The metal evaporation material 23 is a base material having a specified one kind of metal or a specified plurality of types of metals as a main component, and a metal material containing trace impurities in the base material and an additive metal added to the metal material, and impurities of the metal material In order to achieve a content ratio of less than 0.01% by weight, the metallic material contains more than 99.99% by weight of the base material.

The metal is added at a temperature of 700 ° C or higher, and has a low vapor pressure property of a metal having a vapor pressure of less than 1/10000 of the vapor pressure of the base material at the same temperature. Therefore, when the metal evaporation material 23 is heated to melt it, Among the vapors emitted from the molten material of the metal evaporation material 23, the metal-added vapor becomes less than 1/10000 of the vapor of the base material, and a thin film made of a high-purity base material can be formed on the surface of the substrate 14. on.

The base material of the metal evaporation material 23 is a metal that does not dissolve W or Mo constituting the high melting point metal container 22. Therefore, among the molten material of the metal evaporation material 23, the high melting point metal constituting the high melting point metal container 22 is not melted. However, if gas is released from the high-melting-point metal container 22 that has been heated to a high temperature, the gas system is mixed into the molten material of the metal evaporation material 23.

The additive metal contained in the metal evaporation material 23 has a property (reactivity) that reacts with the gas emitted from the metal evaporation material 23 to generate a reaction product. Therefore, if the metal evaporation material released from the high-melting metal container 22 is mixed into the metal evaporation material, The gas in the melt of 23 reacts with the addition of a metal in the melt of the metal evaporation material 23 to generate a reaction product in the melt of the metal evaporation material 23.

At a temperature of 700 ° C. or higher, the reaction product has a low vapor pressure property of a product having a vapor pressure that is less than 1/10000 of the vapor pressure of the base material at the same temperature as the temperature of the reaction product.

Therefore, since the content of the vapor of the reaction product in the vapor generated from the molten material of the metal evaporation material 23 is less than 1/10000 of the vapor of the base material, the reaction product reaching the surface of the substrate 14 is a small amount. Thin film of high purity base material.

FIG. 2 is a graph showing the relationship between the temperature of the base metal Au, the refractory metal W, and the oxides WO ₂ and WO ₃ of the refractory metal W and the vapor pressure. From the graph, it can be seen that the vapor pressure of WO ₃ is larger than the vapor pressure of Au, and the vapor pressure of WO ₂ is close to the vapor pressure of Au. Therefore, it is easy to contain WO ₂ or WO ₃ in the melt of the Au base material. Bumps occur. Furthermore, in this figure and the figures described later, "1.E + n" where n is a numerical value means 1.0 × 10 ⁿ , and "1.En" means 1.0 × 10 ^-n .

FIG. 3 is a graph showing the relationship between the temperature of the base material Au, the highly reactive metals Ti, Hf, Zr, and Ta and the vapor pressure. The Ti, Hf, Zr, and Ta systems are highly reactive with oxygen or organic gases, but among these metals, Ti has a vapor pressure that is closer to the base metal Au than Hf, Zr, and Ta, which are added metals. Due to the vapor pressure, when the metal evaporation material 23 containing Ti is melted to generate vapor, the vapor contains a high concentration of Ti vapor, so it is not suitable to use Ti as an additive metal.

FIG. 4 is a graph showing the relationship between the temperature and vapor pressure of Au, oxides TiO, TiO ₂ , ZrO ₂ , HfO ₂ , and Ta ₂ O _{5 in} the base material. The content of Ti oxides (TiO, TiO ₂ ) in Au vapor is large, but it is obvious that the content of ZrO ₂ , HfO ₂ , Ta ₂ O ₅ as the oxides of added metals is small, so it can be known that Zr and Hf Suitable for Ta as additive metal.

    Examples    

An Au ingot having a purity of 99.999% (5N) was melted in a vacuum environment and degassed to obtain a 5N Au metal material. The content rate was changed, and the added metal was added to the metal material to obtain a metal evaporation material. Moreover, without adding the added metal, a metal evaporation material composed of the metal material is obtained.

These metal evaporation materials are arranged in the vapor deposition device 11 of FIG. 1, and are heated to evaporate. On the surface of the substrate 14 composed of a 4-inch (4-inch diameter) Si wafer, the film formation rate was changed to form an Au film with a film thickness of 250 nm. In the evaporation 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 to make the film formation rate constant.

The following Table 1 shows vapor deposition conditions when a metal evaporation material to which no added metal is added is placed in a high-melting-point metal container (hearth liner) 22 made of W and vapor deposition is performed.

In addition, Table 2 below shows the vapor deposition conditions during deposition when a metal evaporation material 23 prepared by adding 2.5 wt% of Ta as a metal added to a metal material is placed in a high-melting-point metal container 22 made of W. The following Table 3 shows the conditions for vapor deposition when it is directly placed in a copper container body 21 and vapor-deposited.

In addition to the addition of metals, in addition to Ta, Zr, Hf, and Nb have the same vapor pressure as Au, which is extremely lower than that of Au, and is active against a wide range of outgassing. It has low vapor pressure properties of metals and products. Because of its low vapor pressure, Zr, Hf, and Nb also have the same effect of reducing splashes as Ta.

After the Au thin film was formed, the number of particles having a particle diameter of 0.2 μm to 1.5 μm was measured, and the number of particles was determined as the number of spatter adhesion (number of foreign matter adhesion).

The following Table 4 shows the case where the high-melting-point metal container 22 is not arranged in the container body 21 and the metal evaporation material 23 is placed in contact with the copper exposed on the surface of the container body 21 when using an additive metal composed of Ta The measurement results are shown in Table 5 when using an additive metal composed of Zr.

The following Table 6 shows a case where a high-melting-point metal container 22 made of W is arranged in the container body 21, and the metal evaporation material 23 is arranged in contact with the surface of the high-melting-point metal container 22 in the high-melting-point metal container 22 and melted. In this case, the measurement results when the additive metal made of Ta is used are shown in Table 7. Table 7 shows the measurement results when the additive metal made of Zr is used.

From the measurement results described in Tables 4 and 5, it was found that the number of spatter adhesion was significantly reduced by adding 0.1 wt% or more of the additive metal.

In particular, compared with a metal evaporation material composed of an Au base material that has been subjected to vacuum melting but no added metal, the number of spatter (foreign matter) adhered to the metal evaporated material 23 to which 2.5% by weight of added metal is added. Reduced to about 1/13.

No significant change was seen when the content of the added metal was within the range of 2.5 wt% to 10 wt%, but good results were obtained in either case.

Since the gas is emitted from the high-melting-point metal container 22, when the metal evaporation material 23 is disposed in the high-melting-point metal container 22 for vapor deposition, the number of splash adhesion is higher than when the metal evaporation material 23 is directly disposed in the container body 21 for vapor deposition. More increase.

However, compared with a metal evaporation material composed of an Au base material that has been vacuum-melted but no added metal is added, in Table 6, by adding 0.1 wt% or more of Ta to the Au base material, splashing can be adhered. The number was reduced to about 1/3.

Furthermore, by increasing the amount of Ta added to Au to 2.5% by weight, the number of spatter attachments is greatly reduced, compared to a metal evaporation material made of the Au base material that has been vacuum melted but no added metal has been added. Can be reduced to 1/25.

No significant change was seen when the content of Ta was in the range of 2.5% to 10% by weight, but good results were obtained at any content.

In addition, according to Table 7, when Zr was contained in the Au base material as the additive metal, the effect of reducing the number of spatter adhesion was also seen when it contained Ta as the additive metal.

The following Table 8 shows the number of splashes when a metal evaporation material using Ti as the added metal is placed in a high-melting-point metal container 22 made of W and melted. The Ti system has fewer spatters than Ta or Zr, but as shown in Table 9, the resistivity of the Au film obtained by using Ti as the metal evaporation material is more than that of the metal composed of the Au-free base material. The resistivity of the Au film obtained from the material is higher, so it is judged that the Au film contains a high concentration of Ti. In the metal evaporation material 23 using Ta or Zr as the additive metal, the resistivity is the same value as the resistivity of the Au thin film obtained from the metal evaporation material composed of the Au-free base material. Contains added metals.

The above is the use of Au in the base material, but even if the base material is other metals, as long as it does not dissolve W or Mo and has a low vapor pressure of metal and a product with low vapor pressure of the added metal is added to the metal evaporation material Then, the present invention is also applicable to metal evaporation materials of metals other than Au.

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

Claims (5)

    A metal evaporation material is a metal material having a specified one or more kinds of metal as a base material, and a metal evaporation material added with the metal added to the foregoing metal material, characterized in that the foregoing added metal has: at 700 A temperature lower than ℃, a metal having a low vapor pressure of less than 1 / 10,000 of the vapor pressure of the aforementioned base material, and a reactivity that reacts with a gas contained in the aforementioned metal evaporation material to form a reaction product And the reaction product has a low vapor pressure property at a temperature of 700 ° C. or higher and a vapor pressure of 1/10000 or less of the vapor pressure of the base material of the aforementioned base material.         The metal evaporation material according to claim 1, wherein the aforementioned metal evaporation material is arranged in contact with a high melting point metal container made of a high melting point metal and is melted.         The metal evaporation material according to claim 2, wherein oxygen is contained in a gas released from the high-melting-point metal, and the reaction product is an oxide of the added metal.         For example, the metal evaporation material of claim 2 or 3, wherein the high melting point metal is any one of W and Mo, and the metal of the base material of the metal material is Au containing impurities in a range of not more than 0.01% by weight.         The metal evaporation material according to claim 4, wherein the added metal is composed of at least any one of the foregoing metal elements among the metal elements of Ta, Zr, Hf, or Nb.