JPS63227771A - High purity titanium silicide target for sputtering and production thereof - Google Patents

Abstract

PURPOSE:To suppress incorrect working by the influence of impurities and to improve the resistance, corrosion and oxidation resistances by sintering powder obtd. by pickling crushed high purity titanium silicide. CONSTITUTION:High purity titanium and silicon are melted in vacuum to produce high purity titanium silicide. This titanium silicide is crushed, pickled and dried. The resulting high purity titanium silicide powder is sintered at a temp. below the m.p. to obtain a target for sputtering having >=99.99% titanium silicide content and >=80% relative density. The impurities in the target are restricted to <=10ppm metallic impurities, <=50ppm C, <=500ppm O2, <=10ppm H2, <=50ppm N2 and <=1ppm other impurities.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sputtering target made of high-purity titanium silicide and a method for manufacturing the same.

More specifically, metal impurities are 10 ppm or less and carbon is 5
0 ppm or less, gas component is oxygen 500 ppm or less,
The present invention relates to a sputtering target made of high-purity titanium silicide in which hydrogen is 50 ppm or less, nitrogen is 50 ppm or less, and all other components are j ppm or less, and a method for manufacturing the same.

Sputtering targets made of high-purity titanium silicide are used for forming gate electrodes or wiring materials deposited on substrates in high-density, high-speed MOE+ integrated circuits.

[Conventional technology]

With the progress from L8 technology to VLSI, higher density and higher integration have progressed, resulting in delays in signal transmission time that are difficult to deal with with polycrystalline silicon, which is the conventional wiring gate electrode material. For this reason, high melting point metal silicides are attracting attention as an alternative to this, and among them titanium silicide has low resistance and excellent corrosion resistance and oxidation resistance.

Methods for forming a silicide film include sputtering using a co-sputtering 9 alloy target, sputtering using a mosaic target, and the OVD method, but sputtering using an alloy target is the most superior in terms of mass productivity.

Conventional sputtering targets made of titanium silicide have been manufactured by sintering titanium powder and silicon powder. However, the purity of the powder is extremely poor because a large amount of impurities are mixed in when it is pulverized, and as a result, only a purity of about 99% can be obtained as a target.

Furthermore, even if sputtering targets are manufactured using bulk raw materials with good purity, titanium silicide is chemically extremely active, so a large amount of impurities will be mixed in during the target formation process, resulting in the final product being Targets can only be obtained with very poor purity, and these targets are likely to malfunction due to the influence of impurities.

Therefore, as an electrode material, molybdenum silicide, which has relatively high purity, is leading the way.

However, since titanium silicide is superior to molybdenum silicide in terms of low resistance, a target made of extremely high purity titanium silicide is desired.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a sputtering target made of high-purity titanium silicide, which has been difficult to achieve with conventional techniques, and a method for manufacturing a sputtering target made of high-purity titanium silicide, which completely prevents the contamination of impurities.

[Means for solving problems]

As a result of intensive studies to solve the above problems, the present inventors discovered that a sputtering target made of high-purity titanium silicide could be obtained by using acid-washed titanium silicide powder, and completed the present invention. I ended up doing it.

That is, in the present invention, the metal impurities are 10 ppm or less.

Carbon is 50 ppm or less, gas component is acid - Jg500
ppm or less, hydrogen 50 ppm or less, nitrogen 50 ppm or less
The following provides a sputtering target made of high-purity titanium silicide, in which all other components are 1 ppm or less, has a substantially uniform composition, has a purity of 99.991 or more, and a relative density of 80 or more, and a method for producing the same. It is something.

In this specification, the purity of titanium silicide refers to the purity excluding gas components.

Next, a method for manufacturing a sputtering target made of high-purity titanium silicide according to the present invention will be described.

First, high-purity titanium and silicon are subjected to a vacuum melting or atmospheric arc melting process. The raw materials used are relatively large blocks or ingots of high-purity titanium and silicon. A high-purity titanium silicide lump can be obtained by weighing a predetermined amount of these, subjecting them to a melting reaction in a vacuum or an atmospheric arc melting reaction, and simultaneously purifying them. In this process, low melting point impurities, alkali metals, alkaline earth metals, and hydrogen are particularly removed. The method of vacuum melting reaction is not particularly limited, such as electron beam melting, high frequency melting, vacuum arc melting, etc., but electron beam melting is the most preferable method considering the purification effect.

The high-purity titanium silicide mass obtained through the melting process is
In the pulverization process, pulverization is performed using a pulverizer to obtain titanium silicide powder.

The crusher may include a show crusher, a rod mill, a roll mill, etc., and is not particularly limited, but it is preferable to use a crusher whose contact surface with the material to be crushed is made of iron or an iron-based alloy that is soluble in acid.

Further, the pulverization is performed so that the particle size is about 5 to LO15 ns, and depending on the pulverizer, the pulverization may be repeated several times. However, it is preferable to remove fine powders, especially fine powders with a particle size smaller than α01, because they have high activity and may cause contamination with impurities.

Next, for impurities and pulverization in the titanium silicide powder, an acid such as hydrofluoric acid or a mixed acid containing two or more of these acids can be used, but in the present invention, it is not particularly limited as long as it dissolves iron-based impurities.

Since titanium silicide is relatively stable against acids compared to simple metals, the acid concentration can be increased during acid cleaning. The concentration of the acid used varies depending on the type of acid, but it is carried out at 111L1N to 5N. If α is less than 1N, impurities may not be removed, and if it exceeds 5N, the titanium silicide powder after cleaning becomes too active.
It tends to become difficult to handle. The temperature during acid washing also varies depending on the type of acid, but conditions of room temperature to 90°C are preferable, and in consideration of efficiency, acid washing is preferably carried out at a temperature of 60°C to 80°C. When using nitric acid, sulfuric acid, or a mixed acid thereof, it is preferable that the concentration be 1N or less and the temperature be 50° C. or less because of its oxidizing effect. Further, although the atmosphere for acid cleaning is not particularly limited, it is preferable that the button be cleaned in an inert gas atmosphere to prevent oxidation. If the metal contamination after pulverization is severe, magnetic separation may be performed before cleaning. Magnetic sorting can reduce the burden of the acid washing process. Further, when drying the high-purity titanium silicide powder after acid washing, it is preferable to dry the powder in a vacuum or in an inert gas atmosphere because oxidation can be prevented.

Next, a sintering process is performed in which the high purity titanium silicide powder obtained by refining, alloying, pulverizing, and acid washing is sintered under pressure as described above. Sintering methods include hot isostatic pressing (H-P) and hot pressing (HP). Pressureless sintering is unsuitable because a high-density target cannot be obtained. When sintering is performed by hot isostatic pressing, high-purity titanium silicide powder is embedded in a capsule filled with a 11W agent, vacuum-sealed, and pressed together with the capsule. This mold release agent is particularly important in terms of preventing impurities from entering the high-purity titanium silicide powder, preventing reaction between the high-purity titanium silicide powder and the capsule, and preventing cracking of the target due to springback.

As the mold release agent, a powder containing any one of alumina, zirconia, and boron nitride, or a paper or cloth-like molded body can be used, and these mold release agents can also be used in combination. In addition, the type of capsule may be made of materials such as iron, copper, metal, glass, etc., but is not particularly limited in the present invention.The pressure of the press is 200
It may be carried out at a rate of kg/cd or more, but in order to obtain a high-density target, it is preferable to carry out the process at a rate of 500 to 9/i or more. Further, the temperature during pressing may be 500° C. or higher and below the melting point, but in order to promote sintering, K is preferably 1100° C. or higher and lower than the melting point. This retention time is 4
Although the time is not limited to 9, it is preferable to set the time to 30 minutes or more in order to promote sintering.

- When sintering is performed by hot pressing, high-purity titanium silicide powder is immersed in a mold release agent filled in a hot press mold and then pressed. The mold release agent may be the same as the mold release agent used when performing hot isostatic pressing. In addition, hot pressing is performed in a vacuum or in an inert gas atmosphere to prevent impurities such as oxygen and nitrogen from entering the high-purity titanium silicide powder. Alternatively, high-purity titanium silicide powder may be embedded in a capsule filled with a mold release agent, vacuum sealed, and pressed together with the capsule. At this time, in order to apply pressure uniformly, it is preferable to fill a hot press mold with pressure medium particles and bury the above-mentioned capsules therein and press. The pressure medium particles are not particularly limited, but include alumina, zirconia, boron nitride, and the like. The pressing pressure may be 200 kg/ff1 or more, but in order to obtain a high-density target, it is preferably 500 kg/cr/1 or more. Also, the temperature during pressing is 500
C. or more and below the melting point, but in order to promote sintering, it is preferably carried out at 1100.degree. C. or more and below the melting point. This holding time is not particularly limited, but in order to promote sintering, K is preferably 30 minutes or more.

A sintered body made of high-purity titanium silicide is obtained through the above steps, and a sputtering target is obtained by cutting or polishing this into a predetermined shape.

〔Effect of the invention〕

The sputtering target made of titanium silicide of the present invention has (1) a content of each metal impurity component of 10 ppm or less.

(2) In particular, the content of alkali metals such as sodium and potassium is 10 ppb or less.

(3) Gas components: Oxygen 500 ppm or less, Hydrogen 1
0 ppm or less, Nitrogen 50 ppm or less = quantity surveyor,'' Go-Ro Fumigo.

(4) The carbon content is 50 ppm or less, and all other components are 1 ppm or less.

(5) Purity is 99.99% or higher.

(6) Relative density is 80% or more.

(7) The composition is substantially uniform.

Therefore, malfunctions due to the influence of impurities are less likely to occur. In addition, these sputtering targets have excellent properties such as low resistance, corrosion resistance, and oxidation resistance, so they can be used as gate electrodes or wiring materials deposited on substrates in high-density, high-speed MO8 integrated circuits. It can be suitably used for the preparation of etc.

Furthermore, since the target is of high density, the sputtering rate is improved.

According to the method for manufacturing a sputtering target of the present invention, a sputtering target made of the above-mentioned high-purity titanium silicide can be manufactured without generating cracks in the target due to springback or the like during the sintering process.

〔Example〕

EXAMPLES The present invention will be explained below with reference to Examples, but the present invention is not limited to these Examples in any way.

Example 1 Melting process Metallic titanium 99.99 with relatively high purity as shown in Table 1.
150 g and 1 9999999% silicon, respectively.
76g was weighed, electron beam melted, reacted, and purified at the same time. The impurities contained in the titanium silicide lump obtained at this time and their contents are also shown in Table 1.

Grinding process A titanium silicide lump as shown in Table 1 is ground by a di-crusher with teeth made of manganese cast steel, and the particle size is a, 44~
A titanium silicide powder of llL25wm was obtained. This powder contained many impurities as shown in the analysis values shown in Table 2.

Table 2 Acid Washing Process The titanium silicide powders shown in Table 2 were washed with hydrochloric acid and then vacuum dried to obtain high purity titanium silicide powders.

At this time, the hydrochloric acid concentration is set to 11-S, ON, and the cleaning temperature is set to 60.
Table 3 shows the impurities and their contents in the high purity titanium silicide powder obtained under each condition.

Table 3 Sintering process In the above acid washing step, the hydrochloric acid concentration is 2. ON.

High purity titanium silicide powder obtained under acid cleaning conditions at a cleaning temperature of 60°C was sintered.

Sintering is as follows: (4) A method in which high-purity titanium silicide powder is embedded in a 5UI9 metal capsule filled with an alumina mold release agent, vacuum sealed, and hot isostatically pressed together with the capsule.

φ) A method in which high-purity titanium silicide powder is buried in an alumina mold release agent filled in a hot press room and hot pressed in a vacuum.

(C) High-purity titanium silicide powder is vacuum-sealed into a capsule in the same manner as in (A), and the capsule is embedded in a hot press mold filled with alumina as pressure medium particles, so that it is heated together with the capsule. How to do a press.

Sintering was performed by changing the temperature and pressure during pressing.

Table 4 shows the conditions during sintering and the relative density of the obtained sintered body made of high purity titanium silicide.

Table 4 Electron beam melting process of targeted titanium and silicon, coarse pulverization process using a show crusher, cleaning process of washing with 2N, 60°C hydrochloric acid and vacuum drying, and using alumina powder as a mold release agent at a temperature of 1250°C. °C, pressure cuff 5 o
A hot isostatic press was performed at kg/cIl, and the resulting sintered body made of high-purity titanium silicide was cut and polished to obtain a sputtering target.

Table 5 shows the purity of the target finally obtained.

Example 2 The melting process was atmospheric arc melting, and the crushing process, cleaning process, sintering process, and targeting were performed in the same manner as in Example 1. As a result, a target containing almost the same impurities as in Example 1 was obtained.

[Brief explanation of the drawing]

Figure 1 shows that high-purity titanium silicide powder is used in the present invention.
FIG. 3 is a cross-sectional view showing an example of a state in which a capsule is embedded in a mold release agent filled in a capsule and sealed in vacuum. The capsules are hot isostatically pressed or hot pressed. 2 and 5 are cross-sectional views showing an example of a set state in a hot press.

Claims (12)

[Claims] (1) Metal impurities are 10 ppm or less, carbon is 50 ppm
The following gas components are 500 ppm or less of oxygen and 10 ppm of hydrogen.
m or less, nitrogen 50 ppm or less, all other components are 1
A sputtering target made of high-purity titanium silicide with a purity of 99.99% or more and a relative density of 80% or more. (2) High purity titanium and silicon are vacuum melted or atmospheric arc melted to produce high purity titanium silicide, which is pulverized, washed with acid and dried to produce high purity titanium silicide powder, which is sintered at a temperature below the melting point. containing 10 ppm or less of metal impurities,
High purity titanium silicide with a carbon content of 50 ppm or less, oxygen content of 500 ppm or less, hydrogen 10 ppm or less, nitrogen 50 ppm or less, and all other components of 1 ppm or less, with a purity of 99.99% or more and a relative density of 80% or more. A method for manufacturing a sputtering target consisting of: (3) High-purity titanium silicide is milled with a particle size of approximately 5
The method for producing a sputtering target according to claim 2, wherein the sputtering target is ground to 0.01 mm to 0.01 mm, washed with acid, and dried in a vacuum or an inert gas atmosphere. (4) A sputtering target according to claim 2 or 3, in which the high-purity titanium silicide is pulverized with a pulverizer whose contact surface is made of acid-soluble iron or iron-based alloy and washed with acid. manufacturing method. (5) Claim 2 in which the acid is hydrochloric acid, nitric acid, sulfuric acid, hydrofluoric acid, or a mixed acid containing two or more of these.
A method for manufacturing a sputtering target according to any one of items 1 to 4. (6) The method for producing a sputtering target according to any one of claims 2 to 5, wherein the acid concentration is 0.1N to 5N. (7) Sintering high-purity titanium silicide powder by hot isostatic pressing (HIP) or hot pressing (HP),
Claim 2, which is a sintered body with a relative density of 80% or more
A method for manufacturing a sputtering target according to any one of items 6 to 6. (8) High purity titanium silicide powder is buried in a hot press mold filled with a mold release agent and hot pressed in a vacuum or inert gas atmosphere. A method for manufacturing a sputtering target as described in 2. (9) High purity titanium silicide powder is embedded in a capsule filled with a mold release agent, sealed under vacuum, and hot pressed together with the capsule, according to any one of claims 2 to 8. A method for manufacturing a sputtering target. (10) High purity titanium silicide powder is buried in a capsule filled with a mold release agent and vacuum sealed, and the capsule is further buried in a hot press mold filled with pressure medium powder and hot pressed together with the capsule. Claim 2
9. A method for manufacturing a sputtering target according to any one of items 9 to 9. (11) High-purity titanium silicide powder is embedded in a capsule filled with a mold release agent, vacuum-sealed, and hot isostatically pressed together with the capsule. A method for manufacturing a sputtering target as described in 2. (12) When sintering high-purity titanium silicide,
The sputtering target according to any one of claims 2 to 11, which uses a powder, plate, paper, or cloth-like molded body containing any one of alumina, zirconia, and boron nitride as a mold release agent. Production method.