JP2861383B2 - Silicide target and method for manufacturing the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a silicide target used for sputtering in a semiconductor process or the like, and a method for manufacturing the same.

"Prior Art" As is well known, a sputtering method is one of the techniques for forming a thin film on the surface of a semiconductor wafer such as a silicon wafer. In this sputtering method, atoms and the like are ejected from a target by colliding ions or the like at a high speed with a surface of a target made of a material constituting a thin film formed on a surface of a substrate such as a wafer, and the atoms are arranged facing the target. This is a technique for attaching the wafer to the surface of a wafer.

By the way, in recent years, high-melting metals such as W, Mo, Ta, Ti, Cr, Zr, and Hf, and Si
A silicide film, which is a compound of the above, is being developed.

A target used for forming the silicide film is generally manufactured by mixing a powder of a high melting point metal and a powder of Si, compression molding, and sintering the compact. The target thus manufactured has a structure in which free Si particles are dispersed in crystal grains of a compound (intermetallic compound) of a refractory metal and Si.

`` Problems to be Solved by the Invention '' By the way, when sputtering is performed using the target, Si is ejected from the target as an atom. They adhere as particles, which is one of the causes of defective products.

Therefore, the present inventors have conducted intensive studies on the cause of Si jumping out from the target as particles, i.e., the generation of particles.As a result, in the target structure, when the dispersion of the released Si particles is not uniform, the Si particles are released.
It has been found that this occurs when the particle size of the Si particles is large.

"Object of the Invention" The present invention has been made based on the above findings,
An object of the present invention is to provide a silicide target capable of minimizing particle generation by reducing the particle size of liberated Si particles and uniformly dispersing the particles, and a method for manufacturing the same.

[Means for Solving the Problems] To achieve the above object, the silicide target of claim 1 of the present invention has an average particle diameter of Si particles released from a compound of a high melting point metal and Si of 30 μm or less. And, on any surface and any cross-section, uniformly dispersed such that the number of free Si particles having a particle size of 40 μm or more is 50 or less in a range of 1 mm square. It is.

According to a second aspect of the present invention, there is provided the silicide target according to the first aspect, wherein the refractory metal is any one of W, Mo, Ta, Ti, Cr, Zr, and Hf.

The method for producing a silicide target according to claim 3 is a method of mixing a high melting point metal powder having a particle diameter of 200 μm or less and a Si powder having a particle diameter of 200 μm or less to form XSi ₂ (where X is a high melting point metal). Is defined as T _M ° C. (T _M −100) to (T _M −
5) After firing at a reaction temperature of ° C., this is pulverized to a particle size of 500 μm or less to produce a raw material powder, and the raw material powder is compressed and sintered at a high temperature, and on any surface and any cross section, The particles are uniformly dispersed such that the number of free Si particles having a particle size of 40 μm or more is 50 or less within a square of 1 mm.

The method for manufacturing a silicide target according to claim 4 is the method according to claim 3, wherein the refractory metal is W, Mo, Ta, Ti, Cr, Zr,
Hf.

[Function] In the silicide target of the present invention, the average particle size of the Si particles released from the compound of the refractory metal and Si is small, and the Si particles are uniformly dispersed. The number of particles generated at the time can be reduced.

Further, in the method for manufacturing a silicide target of the present invention, the average particle diameter of the free Si particles of the manufactured silicide target can be reduced to 30 μm or less, and any surface and any cross section can be obtained. In the method, free Si particles having a particle size of 40 μm or more can be uniformly dispersed in 50 or less within a range of 1 mm square.

"Example" Hereinafter, an example of the present invention will be described.

A powder of W having a particle size of 180 μm or less and a powder of Si having a particle size of 180 μm or less are mixed to obtain a mixed powder, and the mixed powder is reacted at a reaction temperature and a reaction time shown in Table 1 (calcination). ) To obtain 11 kinds of powders having a predetermined composition ratio.

The above reaction temperature is generally XSi ₂ (X = W, Mo, Ta, T
If the temperature at which i, Cr, Zr, Hf) is formed is T _M (° C.),
_{(T M -100) ~ (T} M -5) is preferably a ° C., in the above embodiments is a T _M = 1392 ℃. The defined way reaction temperature is lower than the reaction temperature (T _M -100) ℃, the particle size of the unreacted Si particles exceeds the 30 [mu] m, whereas, (T _M -5) ℃
If X exceeds ₂ , the XSi ₂ becomes coarse and does not sinter.

Next, each of the above 11 types of powder was pulverized to a particle size of 50.
11 kinds of raw material powders of 0 μm or less are obtained.

If the particle size of the pulverized particles exceeds 500 μm, the density becomes low and voids or the like are easily generated in the target.

Next, each raw material powder is sintered by a vacuum hot press to obtain 11 types of high-density sintered bodies.

The sintering is performed under a vacuum of 5 × 10 ⁻⁴ Torr with a pressure of 150 kgf / cm ² and a temperature of 1380 ° C.

Next, each of the sintered bodies is machined into a predetermined shape to form 11 types of targets.

The surface of each target obtained in this way is polished, and each polished surface is separated by a microscope with a magnification of 100 times and free.
The i particles were observed, the average particle diameter of the Si particles was measured, and the number of free Si particles having a particle diameter of 40 μm or more was determined within a 1 mm square. The results are shown in Table 1 on the next page.

As is clear from Table 1, in the target of this example, the average particle size of the free Si particles is 6.1 to 25.
It is found that the thickness is in the range of 5 μm, and in each case it is 30 μm or less. The average particle size of the Si particles tends to increase as the reaction temperature increases and as the reaction time increases.

In the target of this embodiment, the number of free Si particles having a particle size of 40 μm or more is in a range of 14 to 45 in a range of 1 mm square on the surface of the target, and each is 50 or less. It turns out that.

Next, as Comparative Examples 1 and 2, W having a particle diameter of 180 μm or less was used.
Powder and Si powder having a particle size of 180 μm or less were mixed to obtain a mixed powder, and the mixed powder was reacted at a temperature different from that in the above example to obtain two types of powders. By pulverizing, two types of raw material powders having a particle size of 500 μm or less are obtained. In Comparative Example 3, the particle diameter was 212.
A powder of W having a particle size of not more than μm and a powder of Si having a particle size of not more than 212 μm are mixed to obtain a mixed powder, and the mixed powder is reacted (fired) at a reaction temperature and a reaction time shown in Table 1. Powder is obtained, and this powder is pulverized to a particle size of 50.
A raw material powder of 0 μm or less is obtained. Further, as Comparative Example 4, a powder of W having a particle size of 180 μm or less and a powder of Si having a particle size of 180 μm or less were mixed to obtain a mixed powder, and reacted (fired) in the same manner as described above. Get the powder,
This powder is pulverized to obtain a raw material powder having a particle size of 600 μm or less.

Then, each raw material powder was sintered by vacuum hot pressing under the same conditions as in the above example to obtain four types of sintered bodies, and each sintered body was machined into a predetermined shape to form four types of targets. .

Then, the average particle size of the free Si particles was measured in the same manner as in the above example, and the number of free Si particles having a particle size of 40 μm or more was determined within a range of 1 mm square. Table 1 shows the results.

Next, sputtering was actually performed using the targets of the above examples and the targets of the comparative examples. The sputtering conditions are as follows.

Sputtering method: DC magnetron sputtering Target dimensions: φ127 × 5t (unit: mm) Substrate: φ4 ″, silicon wafer Ar pressure: 3 × 10 ^-3 Torr, silicide film thickness: 3000Å Power: DC500V × 0.8A Using each target, a silicide film was formed on the surface of each of the 15 silicon wafers, and the number of particles generated on the surface of the silicide film was examined, and the results are shown in Table 2 on the next page. In the sputtering using each target, a silicide film was continuously formed on a silicon wafer.

As is clear from Table 2, in the sputtering using the targets of Examples 1 to 11, the number of generated particles is between 70 to 169, which is smaller than that of the targets of Comparative Examples 1 to 4. Moreover, it is understood that the variation is small.

Further, as is clear from Tables 1 and 2, in the targets of Examples 1 to 7, the number of free Si particles having a particle size of 40 μm or more in a range of 1 mm square was determined in Examples 8 to 11. In the sputtering using the targets of Examples 1 to 7, the number of particles is smaller than that of the targets of Examples 8 to 11. This indicates that the number of particles generated by uniformly dispersing the free Si particles can be reduced.

Furthermore, in the targets of Examples 1 to 7, the average particle size of the free Si particles is smaller than that of the targets of Examples 8 to 11, and the sputtering by the targets of Examples 1 to 7 is smaller than the targets of Examples 8 to 11. Small number of particles. This indicates that the number of particles generated by reducing the average particle size of the free Si particles can be reduced.

In the above embodiment, W is used as an example of the high melting point metal. However, similar effects can be obtained by using Mo, Ta, Ti, Cr, Zr, Hf, or the like in addition to W.

[Effects of the Invention] As described above, according to the silicide target of the present invention, the average particle diameter of Si particles released from the compound of the refractory metal and Si is 30 μm or less, and any surface and any surface In the cross section, the particle size is 40 mm within 1 mm square.
Since the free Si particles having a size of μm or more were uniformly dispersed to be 50 or less, the size of the free Si particles was small, and the Si particles were uniformly dispersed. The number of particles generated at the time can be reduced.

According to the method for manufacturing a silicide target of the present invention, a high melting point metal powder having a particle size of 200 μm or less and a Si powder having a particle size of 200 μm or less are mixed to form XSi ₂ (where X is after the temperature of forming a refractory metal) and fired at a reaction temperature of T as _{M ℃ (T M -100) ~} (T M -5) ℃,
This is crushed to a particle size of 500 μm or less to produce a raw material powder,
This raw material powder is compressed at a high temperature by a hot press and sintered, and free Si particles having a particle size of 40 μm or more are formed on any surface and any cross section within a range of 1 mm square.
Since the particles are uniformly dispersed so as to be no more than the number of particles, the average particle size of the free Si particles of the manufactured silicide target can be reduced to 30 μm or less, and the Si particles can be uniformly dispersed. Thus, the number of particles generated during sputtering can be reduced.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Kunio Kuramochi, Inventor Central Research Laboratory, 1-297 Kitabukuro-cho, Omiya City, Saitama Prefecture (56) References JP-A-2-47261 (JP, A) JP Hei 2-247379 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C23C 14/34 B22F 3/14

Claims (4)

(57) [Claims] 1. A silicide target comprising a refractory metal and Si, wherein the average particle diameter of Si particles released from a compound of the refractory metal and Si is 30 μm or less, and the average particle diameter is at an arbitrary surface and at an arbitrary cross section. A silicide target characterized by uniformly dispersing free Si particles having a particle size of 40 μm or more to 50 or less within a range of 1 mm square. 2. The high melting point metal is W, Mo, Ta, Ti, Cr, Zr,
2. The silicide target according to claim 1, wherein the target is Hf. 3. A mixture of a high melting point metal powder having a particle size of 200 μm or less and a Si powder having a particle size of 200 μm or less is mixed with XSi _2.
(Where, X is the high melting point metal) after firing at a temperature to form a T _M ° C. The _{(T M -100) ~ (T} M -5) ℃ reaction temperature, which was triturated below the particle diameter 500μm The raw material powder is manufactured by pressing and sintering the raw material powder at a high temperature by a hot press, and on any surface and any cross section, 1 mm
A method for producing a silicide target, characterized by uniformly dispersing free Si particles having a particle size of 40 μm or more to 50 or less in four ranges. 4. The high melting point metal is W, Mo, Ta, Ti, Cr, Zr,
4. The method for producing a silicide target according to claim 3, wherein the method is any one of Hf.