JP2000064032A - Titanium silicide target and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a titanium silicide target which can suppress production of particles to an extremely low level and to provide a producing method of the target. SOLUTION: This titanium silicide target has the molar ratio of Si/Ti ranging >=0.3 to <0.6, and the target is preferably prepared to have two kinds of phases of a Ti5Si3 phase and a Ti phase as the inner compsns. The target is obtd. by mixing TiH2 powder and Si powder in the molar ratio Si/Ti ranging >=0.3 to <0.6, heating the mixture to synthesize titanium silicide powder and then sintering it.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an LSI, a VLSI.
The present invention relates to a titanium silicide sputtering target for forming a thin film, which is used as a diffusion prevention film for a wiring material and an electrode material in a semiconductor device such as. In particular, the present invention relates to a titanium silicide target capable of significantly reducing the generation of particles.

[0002]

2. Description of the Related Art Recently, M ₅ Si ₃ (hereinafter referred to as MSi _0.6 : M = W, as a diffusion prevention film for wiring materials and electrode materials in semiconductor devices such as LSI and VLSI,
Thin films of Ti, Ta, etc.) have come into use. The metal silicide film is formed by sputtering a silicide target for sputtering. As the metal silicide, MSix (M = W, Mo, Ta, Ti, C) used as an electrode or wiring has been used so far.
It is known that x = 2.0 to 3.0) such as o and Cr.
These consist of the MSi ₂ phase and the liberated Si phase. When a film is formed using these targets, the generation of particles becomes a problem.

Up to now, it has been found that coarse particles of the free Si phase are largely involved in the generation of metal silicide particles. That is, when a sputtering target having a structure in which a coarse Si phase is present is sputtered, surface unevenness due to the difference in the sputtering speed between the Si phase and the metal silicide phase becomes remarkable, and this step causes an increase in particles. It is believed that. Based on such recognition, for example, Japanese Patent Laid-Open No. 4-191366 discloses that in a silicide target composed of a refractory metal and Si, the average particle size of free Si particles is 30 μm or less, and the particles on the surface and in the cross section. Disclosed is a silicide target characterized in that the number of free Si particles having a diameter of 40 μm or more is 50 / mm ² or less, and a manufacturing method thereof.

On the other hand, the metal sill used for the diffusion prevention film
So far, MSI _0.6(M = W, T
a, Ti, etc.) are known. These are MSi_0.6
Create a sputtering target with the composition and
To form a film by sputtering. In that case, nitrogen
Reactive sputtering in atmosphere
The film obtained as above is often used. In this
TiSi_0.6, Its composition is TiSi_0.6
It consists of only one phase and is not affected by the free Si phase
Regardless of this TiSi_0.6Composition 1 phase sputter phosphorus
Particles are extremely large when a film is formed using a target
I am getting the result. Erosion of the target
Detailed observation of the surface reveals that the tissue has been destroyed.
A trace that was thought to have been the source of dust was observed. This is T
iSi_0.6Due to the brittleness of the phase itself as a material
, TiSi exposed to plasma during sputtering_0.6
Part of the crystal is destroyed, this fragment is scattered and particles
It is considered to be the source. For this reason, commercialization
Is not progressing easily.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to establish a titanium silicide target capable of suppressing the generation of particles to an extremely low level and a manufacturing technique thereof.

[0006]

The inventors of the present invention have conducted various studies on the titanium silicide target in order to solve the above problems, and as a result, have found that the composition of TiSi is TiSi.
_The present invention was accomplished by discovering that the above-mentioned problem of particles is solved by slightly shifting the Ti phase from the 1-phase of _{0.6 to} an excess of Ti, and that adverse effects caused by compositional changes such as changes in electrical resistance are extremely slight. . That is, T
The brittleness of the iSi _0.6 phase is a property peculiar to the material and is a problem that is difficult to improve. However, in order to obtain a structure in which a brittle material is less likely to be broken during sputtering, it has been studied to surround TiSi _0.6 phase with Ti having high ductility and toughness, and the present invention has been completed.

The present invention is based on the above findings, in the titanium silicide target for thin film formation, Si /
Titanium silicide target characterized in that the molar ratio of Ti is 0.3 or more and less than 0.6

2. The internal composition is Ti ₅ Si ₃ (hereinafter TiS
i _0.6 ) phase and a Ti phase. Two types of titanium silicide targets are provided.

3. TiH ₂ powder and Si powder are replaced with Si / T
A method for producing a titanium silicide target, which comprises mixing titanium silicide powders heated and synthesized after mixing at a molar ratio of i = 0.3 or more and less than 0.6.

4. TiH ₂ powder and Si powder are replaced with Si / T
Ti or TiH ₂ powder was added to Ti / TiH ₂ powder in Si / Ti =
A method for producing a titanium silicide target, characterized in that the titanium silicide powder heated and synthesized is again sintered after additional mixing so as to have a molar ratio of 0.3 or more and less than 0.6.

5. Ti powder and Si powder are Si / Ti =
A method for producing a titanium silicide target, which comprises mixing the titanium silicide powder heated and synthesized after mixing in a molar ratio of 0.3 or more and less than 0.6.

6. Ti powder and Si powder are Si / Ti =
Ti or TiH ₂ powder was added to titanium silicide powder heated and synthesized by mixing at a molar ratio of 0.6, and Si / Ti = 0.
Provided is a method for producing a titanium silicide target, which is characterized in that after the titanium silicide powder that has been heated and synthesized is sintered again, the titanium silicide powder is additionally mixed so as to have a molar ratio of 3 or more and less than 0.6.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In a conventional TiSi _0.6 target, TiH ₂ and Si are mixed so that the molar ratio of Si / Ti is 0.6, which is a stoichiometric ratio, and the mixture is heated in vacuum. A sputtering target was produced using a raw material powder that was subjected to dehydrogenation and silicide synthesis all at once. When sputtering was performed using the target, the generation of particles of 0.2 μm or more was tens of thousands / wafer, but it was found that the present invention can drastically reduce the number to 50-60 particles / wafer. Such a drastic decrease in particles is peculiar to the titanium silicide target, and is not seen in other types of refractory metal silicides.

The titanium silicide target for forming a thin film according to the present invention has a range of x = 0.3 or more and less than 0.6 when the target composition is represented by TiSix. When x is less than 0.3, the amount of oxygen dissolved in the Ti phase increases, the film stress during film formation is high, and the film is easily peeled off, which is not preferable. For this reason, the composition lower limit is set to 0.
Set to 3. On the other hand, when x exceeds 0.6, TiSi
In addition to the particles increases due to the brittleness of _0.6 is remarkable, newly _{Ti 5 Si 4 (TiSi 0 .8} ) phase appears. The phase has brittle characteristics like the TiSi _0.6 phase, and further hinders densification of the target,
It is not preferable because it leads to an increase in particles. Preferably, the titanium silicide target of the present invention has an internal composition of two kinds of TiSi _0.6 phase and Ti phase. As the internal composition consists of two types of TiSi _0.6 phase and Ti phase, Ti with rich ductility and toughness surrounds the TiSi _0.6 phase, which is originally a brittle material, so that it is destroyed during sputtering. It can be made a structure that is hard to be damaged.

The titanium silicide target of the present invention is
It can be produced by any of the following methods (a) to (d). That is, (a) TiH ₂ powder and Si powder are replaced with Si / Ti = 0.3
After mixing in a molar ratio of not less than 0.6, the heat-synthesized titanium silicide powder is sintered. (B) TiH ₂ powder and Si powder are Si / Ti = 0.6
Ti or TiH ₂ powder was additionally mixed to the titanium silicide powder that was heat-synthesized by mixing at a mole ratio of Si / Ti = 0.3 or more and less than 0.6, and then heat-synthesized titanium was mixed again. Sinter the silicide powder. (C) After mixing the Ti powder and the Si powder in a molar ratio of Si / Ti = 0.3 or more and less than 0.6, the titanium silicide powder heated and synthesized is sintered. (D) Ti powder and Si powder were mixed at a molar ratio of Si / Ti = 0.6 to heat-synthesize titanium silicide powder, and
i or TiH ₂ powder with Si / Ti = 0.3 or more.
After additionally mixing so that the molar ratio is less than 6, the titanium silicide powder synthesized by heating is sintered again.

Raw material Si powder and Ti powder or T
The iH ₂ powder has a high purity. In particular, in order to manufacture a sputtering target for manufacturing a semiconductor device, it is desired that impurities contain as few radioactive elements, alkali metals and transition metals as possible. This is to eliminate the soft error caused by α-rays of radioactive elements and the adverse effects caused by the migration of alkali metals and transition metals at the film interface. High-purity Si powder can be easily obtained as a commercial product. Further, regarding the Ti powder and the TiH ₂ powder, the present applicant has now established a technique for producing a high-purity powder in which the above impurities are reduced.

Raw material Si powder and Ti powder or TiH
_{The two} powders are sufficiently mixed in a compounding ratio such that the above-mentioned predetermined molar ratio is obtained. The mixing is performed using, for example, a V-type mixer, a Mo ball mill, or the like.

Silicide synthesis is carried out by heating the mixed powder to about 800 to 1400 ° C. in hydrogen or a vacuum atmosphere. Further, the Ti powder or the TiH ₂ powder may be additionally mixed with the synthetic silicide powder and then heated and synthesized again to obtain the synthetic silicide powder.

The synthetic silicide mass is crushed and sieved to adjust the particle size of the powder. Then, the synthetic silicide powder can be produced into a sintered body by hot pressing or HIP. The hot press conditions are, for example, a temperature of 1000 to 14
00 ° C, pressure 100 to 600 kg / cm ² , pressurization time 1
It takes about 4 hours. HI for HIP processing
The P temperature should be “highest possible temperature in the range where melting does not occur” in order to obtain a high density target.

The obtained titanium silicide sintered body is machined to form a sputtering target.
According to the present invention, the composition of TiSix (x = 0.3 or more, 0.
When observing the condition of the erosion surface after sputtering using the sputtering target prepared in (6) or less,
It was confirmed that almost no destruction of the TiSi _0.6 phase occurred. Further, almost no surface irregularities due to the difference in the sputtering speed between the Ti phase and the TiSix phase were observed.

[0021]

EXAMPLES Examples and comparative examples are shown below, but the contents of the present invention are not limited to the examples.

Example 1 High-purity TiH ₂ powder and high-purity S
The i powder was mixed with a ball mill made of high-purity Mo and heated in a vacuum to perform the dehydrogenation reaction and the silicide synthesis reaction all at once to obtain a synthetic mass of TiSix (x = 0.45). This lump of silicide was pulverized with a ball mill made of high-purity Mo to obtain -200 mesh silicide powder. This silicide powder showed that TiSi _0.6 phase and T
It was confirmed that it consisted of only the i-phase. Using this titanium silicide powder, a sintered body was prepared by a hot pressing method, a target of φ300 mm × 6.35 mmt was prepared by machining, and sputtering was performed to measure particles on a wafer (6 inch type).
The total number of particles having a size of 2 μm or more was 53. Observing the erosion surface of the target, Ti
No damage marks of the Six phase are seen, and the Ti phase and Ti
No surface irregularity due to the difference in the sputtering rate of the Six phase was observed.

(Example 2) High-purity TiH ₂ powder and high-purity S
The i powder was mixed, synthesized, and crushed in the same manner as in Example 1 so as to have TiSix (x = 0.6), and TiSi _0.6 powder of −200 mesh was obtained. This TiSi _0.6 powder and high-purity Ti powder were mixed, synthesized, and crushed again in the same manner as in Example 1 so that TiSix (x = 0.45) was obtained, and -2.
A 00 mesh TiSi _0.45 powder was obtained. This silicide powder was analyzed by XRD to obtain TiSi _0.6 phase and Ti
It was confirmed that it consisted only of phases. Using this titanium silicide powder, a sintered body was prepared by a hot pressing method, a target of φ300 mm × 6.35 mmt was prepared by machining, and sputtering was performed to produce a wafer (6
The particle size on the inch type is 0.2μ.
The total number of particles having a size of m or more was 54. Observing the erosion surface of the target, TiSix
No trace of phase destruction was observed, and Ti phase and TiSix
No surface irregularity due to the difference in the sputtering speed of the phases was observed.

(Example 3) High-purity Ti powder and high-purity Si powder were mixed in a ball mill made of high-purity Mo and heated in a vacuum to carry out a silicide synthesis reaction to produce TiSix.
A synthetic mass of (x = 0.45) was obtained. This lump of silicide was pulverized with a ball mill made of high-purity Mo to obtain -200 mesh silicide powder. This silicide powder is XRD
As a result, it was confirmed that it consisted only of TiSi _0.6 phase and Ti phase. Using this titanium silicide powder, a sintered body was prepared by the hot pressing method, and φ was machined.
When a target of 300 mm × 6.35 mmt was prepared, and sputtering was performed to measure the particles on the wafer (6 inch type), the total number of particles having a size of 0.2 μm or more was 59. When the erosion surface of the target was observed, no trace of the TiSix phase being destroyed was observed, and no surface irregularity due to the difference in the sputtering speed between the Ti phase and the TiSix phase was observed.

Comparative Example 1 High-purity TiH ₂ powder and high-purity S
The i powder was mixed, synthesized, and crushed in the same manner as in Example 1 so as to have TiSix (x = 0.6), and TiSi _0.6 powder of −200 mesh was obtained. This silicide powder is X
It was confirmed by RD that it consisted of only the TiSi _0.6 phase. Using this titanium silicide powder, a sintered body was prepared by a hot pressing method, and was machined to a diameter of 30 mm.
When a target of 0 mm × 6.35 mmt was produced, and sputtering was performed to measure the particles on the wafer (6 inch type), the total number of particles having a size of 0.2 μm or more was 10,000 or more. When the erosion surface of the target was observed, the TiSi _0.6 phase was destroyed, and a trace apparently serving as a dust source was observed.

Comparative Example 2 High-purity TiH_TwoPowder and high purity S
i powder was used as in Example 1 so that TiSix (x = 0.7) was obtained.
-200 mesh, mixed, synthesized and crushed in the same way
TiSi_0.7A powder was obtained. This silicide powder is
TiSi by XRD_0.6Phase and TiSi_0.8Phase of
I confirmed that it consisted of only. This TiSi powder
Using the hot press method to make a sintered body, machining
Create a target of φ300mm x 6.35mmt
Manufactured and sputtered on wafer (6 inch type)
The particle size of 0.2μm or more
The total number of particles was 10,000 or more. Ta
Observing the erosion surface of the target, TiSi
_0.6Phase or TiSi_0.8Phase is destroyed and revealed
A trace of dust that was thought to have been the source of dust was observed.

(Comparative Example 3) High-purity TiH ₂ powder and high-purity S
The i powder was mixed, synthesized, and crushed in the same manner as in Example 1 so as to have TiSix (x = 0.2), and TiSi _0.2 powder of -200 mesh was obtained. This silicide powder is X
It was confirmed by RD that it consisted of only TiSi _0.6 phase and Ti phase. Using this TiSi powder, a sintered body was prepared by the hot pressing method, and was machined to give φ3
A target of 00 mm × 6.35 mmt was prepared, and sputtering was performed to measure the particles on the wafer (6 inch type). As a result, the total number of particles having a size of 0.2 μm or more was 1,200. When the erosion surface of the target was observed, no trace of the TiSix phase being destroyed was observed, and no surface irregularity due to the difference in the sputtering speed between the Ti phase and the TiSix phase was observed. However, the redeposition film on the outer peripheral portion of the target was peeled off, which is considered to be a particle source.

[0028]

The use of the titanium silicide target of the present invention, which has a Si / Ti molar ratio of 0.3 or more and less than 0.6, can suppress the generation of particles to an extremely low level. , LSI, VL
It is useful for forming a diffusion prevention film for wiring materials and electrode materials in semiconductor devices such as SI.

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[Procedure amendment]

[Submission date] October 27, 1999 (1999.10.
27)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0007

[Correction method] Change

[Correction content]

The present invention is based on the above findings. In the titanium silicide target for thin film formation,
Titanium silicide target having a Si / Ti molar ratio of 0.3 or more and 0.45 or less

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

In the titanium silicide target for forming a thin film according to the present invention, when the target composition is represented by TiSix, x = 0.3 or more and less than 0.6, particularly x = 0.3 or more and 0.45. The range is as follows , and the internal composition is T
It is assumed to be composed of two types, iSi _0.6 phase and Ti phase. Within
Part composition consisting of two kinds of TiSi _0.6 phase and Ti phase
As a material that is originally brittle because of its high ductility and toughness, Ti
The TiSi _0.6 phase surrounding the
It is possible to make it a structure that is not easily destroyed during the process. When x is less than 0.3, the amount of oxygen dissolved in the Ti phase increases,
The film stress during film formation is high, and peeling of the film easily occurs, which is not preferable. Therefore, the composition lower limit value is set to 0.3. On the other hand, if x exceeds 0.6, in addition to the particles increases due to the brittleness of _{TiSi 0.6} becomes significant, new _{Ti 5 Si 4 (TiSi 0 .8} ) phase appears. This phase is not preferable because it has brittle characteristics like the TiSi _0.6 phase, further hinders the densification of the target, and leads to an increase in particles.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

The obtained titanium silicide sintered body is machined to form a sputtering target.
According to the present invention, the composition of TiSix (x = 0.3 or more, 0.
When observing the condition of the erosion surface after sputtering using a sputtering target adjusted to less than 6, particularly x = 0.3 or more and 0.45 or less ), it was confirmed that the TiSi _0.6 phase was hardly broken. Was done. Further, almost no surface irregularities due to the difference in the sputtering speed between the Ti phase and the TiSix phase were observed.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirohito Miyashita             4 shares, 187 Usba, Hwagawa-cho, Kitaibaraki, Ibaraki             Ceremony company Japan Energy Isohara factory (72) Inventor Shuichi Irumata             4 shares, 187 Usba, Hwagawa-cho, Kitaibaraki, Ibaraki             Ceremony company Japan Energy Isohara factory F-term (reference) 4G001 BA61 BA62 BB48 BC46 BD38                 4K029 BA52 BD01 DC05 DC09

Claims (6)

[Claims] 1. A titanium silicide target for forming a thin film, wherein the molar ratio of Si / Ti is 0.3 or more and less than 0.6. 2. An internal composition of Ti ₅ Si ₃ (hereinafter referred to as TiSi
The titanium silicide target according to claim 1, wherein the titanium silicide target is composed of two types of a _0.6 ) phase and a Ti phase. 3. TiH ₂ powder and Si powder are added to Si / Ti.
= 0.3 or more and less than 0.6, and then, the titanium silicide powder synthesized by heating is sintered, and the method for producing a titanium silicide target. 4. TiH ₂ powder and Si powder are replaced with Si / Ti.
= Ti or TiH ₂ powder is added to the titanium silicide powder that is heat-synthesized by mixing at a molar ratio of 0.6
A method for producing a titanium silicide target, which comprises mixing titanium oxide powder which is heat-synthesized again, after additionally mixing so as to have a molar ratio of 0.3 or more and less than 0.6. 5. A Ti powder and a Si powder are Si / Ti =
A method for producing a titanium silicide target, which comprises mixing titanium silicide powder heated and synthesized after mixing at a molar ratio of 0.3 or more and less than 0.6. 6. A Ti powder and a Si powder are Si / Ti =
Ti or TiH ₂ powder was added to titanium silicide powder heated and synthesized by mixing at a molar ratio of 0.6, and Si / Ti = 0.
A method for producing a titanium silicide target, which comprises mixing titanium silicide powder by heating again after mixing it so that the molar ratio becomes 3 or more and less than 0.6.