JP2002270829A - Silicide target for forming gate oxide film, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MSi2.05-3.0 (M: Zr, Hf) silicide target having proper anti-embrittlement property suitable for forming a ZrO2 .SiO2 or HfO2 .SiO2 film, which can be used as a gate insulation film formed of a material of high permittivity, having characteristics which can be substituted for those of a SiO2 film, and also to provide a method of manufacturing the same. SOLUTION: The silicide target for forming a gate oxide film is made of MSi2.05-3.0 (M: Zr, Hf).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a ZrO ₂ .Si which can be used as a high dielectric gate insulating film.
The present invention relates to a silicide target which is suitable for forming an O ₂ or HfO ₂ .SiO ₂ film and has excellent workability, brittleness resistance and the like, and a method for manufacturing the same.

[0002]

2. Description of the Related Art The thickness of a dielectric gate insulating film greatly affects the performance of a MOS transistor, and it is necessary that the interface with a silicon substrate be electrically smooth and the mobility of carriers does not deteriorate. . Conventionally, a SiO ₂ film has been used as this gate insulating film, but it was the most excellent in view of the interface characteristics. The thinner the SiO ₂ film used as the gate insulating film is, the more the number of carriers (ie, electrons or holes) is increased, so that the drain current can be increased.

[0003] For this reason, the gate SiO ₂ film has always been made thinner each time the power supply voltage is reduced due to miniaturization of the wiring within a range that does not impair the reliability of dielectric breakdown. However, when the thickness of the gate SiO ₂ film is 3 nm or less, a direct tunnel leak current flows, which causes a problem that the gate SiO ₂ film does not operate as an insulating film. On the other hand, the transistor is being miniaturized. However, since the thickness of the SiO ₂ film serving as the gate insulating film is limited as described above, the problem that the miniaturization of the transistor does not make sense and the performance is not improved. Occurred. Further, in order to lower the power supply voltage of the LSI and reduce the power consumption, it is necessary to further reduce the thickness of the gate insulating film. However, if the SiO ₂ film is 3 nm or less, there is a problem of gate dielectric breakdown as described above. There was a limit to thinning itself.

[0004] From the above, recently, SiO 2₂High instead of membrane
A dielectric gate insulating film has been studied. This high dielectric
ZrO is attracting attention as a body gate insulating film.₂・ S
iO ₂Or HfO₂・ SiO₂It is a membrane. This high dielectric
The gate insulating film is relatively thick and is made of SiO₂Capacity equivalent to membrane
The tunnel leakage current can be suppressed.
It has the following features. In addition, SiO₂To Zr or Hf
Since it can be regarded as added, the interface characteristics are also S
iO₂It is expected to be close to Because of this, good quality
ZrO₂・ SiO₂Or HfO₂・ SiO₂High dielectric
Sputter that can easily and stably form gate insulating film
Ring targets are required.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a Z dielectric film which can be used as a high dielectric gate insulating film having characteristics that can replace a SiO ₂ film.
An object of the present invention is to provide a silicide target which is suitable for forming an rO ₂ · SiO ₂ or HfO ₂ · SiO ₂ film and has excellent workability, embrittlement resistance and the like, and a method for manufacturing the same.

[0006]

According to the present invention, there is provided a silicide target for forming a gate oxide film comprising 1 MSi _2.05-3.0 (M: Zr, Hf). 2 A silicide target for forming a gate oxide film, which is made of MSi _2.05-3.0 (M: Zr, Hf) and has a mixed phase with MSi ₂ phase and Si phase. 3. The silicide target for forming a gate oxide film according to the above item 2, wherein the free Si phase is 30 μm or less. 4. The silicide target for forming a gate oxide film according to the above item 2, wherein the free Si phase is 10 μm or less. (5) The silicide target for forming a gate oxide film as described in any one of (1) to (4) above, wherein the relative density is 99% or more. 6 Metal hydride powder (M) powder and Si powder 1: 2.05-1:
_{MSI 2.05-3.0} (M: Zr, H) characterized by being prepared and mixed at a molar ratio of 3.0, and then fired and sintered.
and f) a method for manufacturing a silicide target for forming a gate oxide film. 7. The method for manufacturing a silicide target for forming a gate oxide film according to the item 6, wherein dehydrogenation and silicidation are performed by heating during firing. 8. The method for producing a silicide target for forming a gate oxide film according to the above item 7, wherein the firing is performed at a temperature of 600 ° C. to 800 ° C. I will provide a.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION A high dielectric gate insulating film having characteristics replacing the SiO ₂ film is formed by oxygen reactive sputtering using a ZrSi or HfSi target. This oxide film is made of ZrO ₂ .SiO ₂ or HfO _2.
It is regarded as a hybrid of oxide films represented as SiO ₂ , and a target usually requires a composition of Si / M = 1.0. However, Z added in comparison with SiO ₂
Since rO ₂ or HfO ₂ has a low crystallization temperature, it is crystallized by a heat treatment in a later step, and there has been a problem that a leak current flows through a crystal grain boundary. On the other hand, SiO ₂ is not subjected to heat treatment at 1000 ° C. or more in an amorphous state. From these facts, it has been found that by making the target composition excessively Si, the crystallization temperature can be raised, the leak current can be suppressed, and the decrease in the dielectric constant can be suppressed.

Further, the silicide target of Si / M = 1.0 has the drawbacks of low density, high brittleness, and poor workability, and has a problem of causing an increase in particles due to fracture and scattering of brittle crystals. Furthermore, if the synthesis is incomplete, the residual metal powder will remain in the synthetic powder, and since the activity of zirconium and hafnium metal is high, cutting powder generated during pulverization or processing of the synthetic powder is ignited. There is danger. That is, when the raw materials are mixed and synthesized with the aim of Si / M = 1.0, the MSi
_{If two} phases are generated, M ₅ Si
₄ (MSi _0.8 ), M ₅ Si ₃ (MSi _0.6 ) and the like are generated, so that Zr or Hf metal powder becomes excessive and remains. Thus, the phase and the lack of metal powder and Si (MSi 0 _.6) is due to the high activity, there may cause fire trouble during and processing during milling. In addition, since the intermetallic silicide has a high melting point, a sufficient increase in density cannot be obtained at the time of sintering, so that there is a problem that the silicide becomes a target that generates many particles. The silicide target for forming a gate oxide film according to the present invention can solve these problems at once.

According to the present invention, MSi _2.05-3.0 (M:
Zr, Hf) is a silicide target for forming a gate oxide film, and has a mixed phase of an MSi ₂ phase and a Si phase. Further, the present invention relates to a silicide target for forming a gate oxide film, wherein a free Si phase in the target is 30 μm or less, preferably 10 μm or less. Generally, a silicide target for forming a gate oxide film has a drawback of high brittleness, but in the present invention, the relative density can reach 99% or more. As a result, a silicide target for forming a gate oxide film having a transverse rupture strength of 200 MPa or more and excellent in embrittlement resistance can be obtained. When the relative density is less than 99% and the free Si phase exceeds 30 μm, the brittleness is reduced due to insufficient density, and the workability is also deteriorated. Furthermore, particles increase due to the destructive scattering of brittle crystals. Therefore, it is desirable to set the above range.

MSi _2.05-3.0 (M: Zr, H
In order to produce a silicide target for forming a gate oxide film having excellent embrittlement resistance comprising f), the metal (M) powder and the Si powder are mixed in a molar ratio of 1: 2.05 to 1: 3.0. Preparation /
After mixing, baking is performed at 600 ° C to 800 ° C. Zr
It is also conceivable to use Zr and Hf powder.
The powder f has a strong oxidizing power and causes a problem of ignition when it is pulverized. Therefore, in order to prevent such ignition,
Use zirconium hydride or hafnium hydride.
These hydrogenated powders and silicon powders are used after being finely pulverized to an average particle size of 10 μm or less. By using this fine powder, it is possible to increase the density during sintering. Dehydrogenation and silicidation are performed by heating during the firing. Dehydrogenation is 600 ° C
Happens from. Sintering is performed in a vacuum (1 × 10 ⁻⁴ to 1 × 10
^-2 Torr), but slightly in a hydrogen atmosphere for dehydrogenation.

As described above, during the heat synthesis, the grain growth is suppressed by performing dehydrogenation and silicidation at a time at a low temperature at which the grain growth does not occur, and the calcined powder remains fine. Density can be increased. When the calcined powder becomes coarse, it is difficult to pulverize it before sintering, so that coarse particles remain and the density decreases. As described above, since the present invention is fired at a low temperature, the present invention has a great feature that growth of crystal grains can be suppressed. And, when sintering, high density can be achieved. In addition, since Si powder is added in excess of the stoichiometric ratio of MSi _{2 at} the time of mixing, sufficient Si is supplied around the metal powder, and almost a two-phase mixture of MSi ₂ phase and Si phase is obtained.
In addition, the excess S
Since i is supplied, at most the MSi phase is formed and the danger of ignition is greatly reduced. A silicide target having a relative density of 99% or more has a transverse rupture strength of 200 MPa or more. The high-density silicide target of the present invention has an effect of preventing generation of particles due to pores during sputtering and generation of particles due to fracture and scattering of a brittle structure.

[0012]

Next, an embodiment will be described. It should be noted that the present embodiment is merely an example of the present invention, and the present invention is not limited to these embodiments. That is, it includes other aspects and modifications included in the technical idea of the present invention.

Example 1 ZrH ₂ powder and Si powder were mixed and heated at 800 ° C. in a vacuum to carry out a dehydrogenation reaction and a silicide synthesis reaction all at once.
_x (x = 2.3) was obtained. This silicide powder was pulverized to obtain a -200 mesh silicide powder. This silicide powder was confirmed by XRD to consist of a mixed phase with the MSi ₂ phase and the Si phase. Using this silicide powder, a sintered body having a density of 99.2% is produced by a hot press method, and φ300 mm × 6.3 is produced by machining.
A 5 mmt target was produced. The free Si phase of this sintered body target was 10 μm. Sputtering was performed using the target thus manufactured, and particles on a 6-inch wafer were measured.
There were a total of 24 particles having a size of 0.2 μm or more, and particle generation was significantly reduced. Furthermore, when the erosion surface of the target was observed, no broken trace of the ZrSi ₂ phase and the Si phase was observed. Also, the result of measuring the transverse rupture force of the target was 223 MPa,
A target rich in workability, embrittlement resistance and the like was obtained. Furthermore, there was no danger of ignition during processing.

(Example 2) ZrH ₂ powder and Si powder were mixed and heated at 800 ° C. in a vacuum, so that the dehydrogenation reaction and the silicide synthesis reaction were performed at once, and ZrSi 2
_x (x = 2.5) was obtained. This silicide powder was pulverized to obtain a -200 mesh silicide powder. This silicide powder was confirmed by XRD to consist of a mixed phase with the MSi ₂ phase and the Si phase. Using this silicide powder, a sintered body having a density of 99.3% is produced by a hot press method, and φ300 mm × 6.3 is machined.
A 5 mmt target was produced. The free Si phase of this sintered body target was 9 μm. Sputtering was performed using the target thus manufactured, and particles on the 6-inch wafer were measured.
There are a total of 33 particles with a size of 2 μm or more,
Particle generation was significantly reduced. Furthermore, when the erosion surface of the target was observed, no trace of breakage of the ZrSi ₂ phase and the Si phase was observed, and no surface irregularities due to the difference in sputtering speed were observed. Further, as a result of measuring the transverse strength of the target, the target was 210 MPa, and a target excellent in workability, brittleness resistance and the like was obtained. Furthermore, there was no danger of ignition during processing. Was.

(Example 3) HfH ₂ powder and Si powder were mixed and heated at 800 ° C. in a vacuum to perform a dehydrogenation reaction and a silicide synthesis reaction all at once.
_x (x = 2.8 and x = 2.2) were obtained. This silicide powder was pulverized to −200 mesh, and mixed to obtain a molar ratio of Si / Hf = 2.5 to obtain a silicide powder. This silicide powder was confirmed by XRD to consist of a HfSi ₂ phase and a Si phase. Using this silicide powder, a sintered body having a density of 99.0% is produced by a hot press method, and φ
A target of 300 mm × 6.35 mmt was produced.
The free Si phase of this sintered body target was 12 μm. Sputtering was performed using the target manufactured in this manner, and particles on a 6-inch wafer were measured. As a result, a total of 30 particles having a size of 0.2 μm or more were found, and the generation of particles was significantly reduced. Further, when the erosion surface of the target was observed, no trace of breakage of the HfSi ₂ phase and the Si phase was observed. In addition, as a result of measuring the transverse force of the target, 2
The target had a pressure of 05 MPa and was excellent in workability, embrittlement resistance and the like. Furthermore, there was no danger of ignition during processing.

(Comparative Example 1) Zr powder and Si powder were mixed,
In vacuum, subjected to a silicide synthesis reaction by heating at 1200 ° _C, to obtain a synthetic powder ZrSi x (x = 1.0). This silicide powder was pulverized to obtain a -200 mesh silicide powder. This silicide powder is XR
D is mainly a ZrSi phase, but a ZrSi ₂ phase,
Zr ₅ Si ₄ (ZrSi _0.8 ) and Zr ₅ Si ₃ (Zr ₅
rSi _0.6 ) was also found to be present. In addition, there was unreacted Zr powder, which accompanied the danger of ignition. Using this silicide powder, a sintered body having a density of 89.0% is manufactured by a hot press method, and φ300 mm × 6.3 is machined.
A 5 mmt target was produced. The crystal grain size of this sintered body target was 100 μm. Sputtering was performed using the target thus manufactured, and particles on a 6-inch wafer were measured.
There were a total of 85 particles having a size of 0.2 μm or more. Furthermore, when observing the erosion surface of the target, it is destroyed ZrSi _x phase, traces that would clearly became dust sources was observed. There were many nodules. Also, as a result of measuring the transverse force of the target, 1
It was 50 MPa. In addition, the workability was poor, and the target was brittle and easily broken.

(Comparative Example 2) Hf powder and Si powder were mixed,
By heating at 1200 ° C. in a vacuum, a silicide synthesis reaction is performed, and HfSi _x (x = 0.67 and 2.
2) Two types of synthetic powders were obtained. After pulverizing this silicide powder to −200 mesh, the molar ratio Si / Hf =
A silicide powder mixed to be 1.0 was obtained. This silicide powder is mainly a HfSi phase by XRD, but is composed of a HfSi ₂ phase and a Hf ₅ Si ₄ (HfS
i _0.8 ) and Hf ₃ Si ₂ (HfSi _0.67 ) were also found to be present. In addition, there is unreacted Hf powder,
With the danger of ignition. Using this silicide powder, a sintered body having a density of 87% was produced by a hot press method, and a target having a diameter of 300 mm x 6.35 mmt was produced by machining. The crystal grain size of this sintered body target is 100
μm. Sputtering was performed using the target thus manufactured, and the particles on the 6-inch wafer were measured. As a result, a total of 110 particles having a size of 0.2 μm or more were found. Furthermore, when observing the erosion surface of the target, it is destroyed HfSi _x phase, traces that would clearly became dust sources was observed. Surface irregularities due to the difference in sputtering speed are seen,
There were many nodules. In addition, as a result of measuring the transverse rupture force of the target, it was 165 MPa. In addition, the workability was poor, and the target was brittle and easily broken.

The free Si phases of the targets of Examples 1 to 3 are all 30 μm or less, and the relative density is 99% or more. The number of particles is 35 or less, and ZrSi _x
Phases or disrupted traces of HfSi _x phase is not observed, transverse rupture strength of the target, 223 MPa, 210 MPa, 205M
Pa, and had a high transverse rupture strength. On the other hand, in Comparative Example 1, the average crystal grain size was as large as 100 μm, and the relative density was as low as 89%. As a result, the number of particles is 85 Ke, after ZrSi _x phase is broken was observed. Nodules are generated and the target has a bending strength of 150
It was as low as MPa, which was a bad result. In Comparative Example 2, the average crystal grain size was as large as 100 μm, and the relative density was 87 μm.
% And low. As a result, the number of particles is less than 120 Ke, after HfSi _x phase is broken was observed. Also,
Surface irregularities due to the difference in sputtering speed were also observed, nodules were generated, and the bending strength of the target was as low as 165 MPa, which was a bad result. In the comparative example, there was unreacted Zr powder or Hf powder, and there was always a danger of ignition during processing. From the above, it is clear that the advantages of the examples of the present invention are excellent, and that they have excellent characteristics.

Next, Examples 1 to 3 and Comparative Examples 1 and 2
Using reactive sputtering in an oxygen atmosphere
A 65 ° metal silicate film was formed. Top and bottom of this thin film
Is an Au electrode, and is suddenly at 1000 ° C. for 20 seconds after film formation.
Rapid heat treatment was performed. After that, patterning is performed
And leakage current characteristics were evaluated. Leakage current to 1.0V
(A / cm²). The results are shown in Table 1.
You. As shown in Table 1, MSi_{2. x}Using the target
Silicate film formed by heat treatment at 1000 ° C
On the other hand, it does not crystallize, resulting in MSi_{1 . 0}
At 1.0 V from the silicate film formed from
Current value (A / cm ²) Is 2 to 4 orders of magnitude better
Was. Dielectric constant of the current SiO₂2 compared to ε = 3.9 for the film
A value of ~ 3 times was obtained.

[0020]

[Table 1]

[0021]

According to the present invention, suitable for the formation of _ZrO 2 · SiO ₂ or _HfO 2 · SiO ₂ film can be used as a high dielectric gate insulating film having a characteristic alternative to the SiO ₂ film, It has a feature that a silicide target having excellent workability, embrittlement resistance and the like can be obtained. The present silicide target can suppress the growth of crystal grains, and can achieve high density during molding. Furthermore, the relative density is 99%
The high-density silicide target has a bending strength of 2
Has excellent strength of 00MPa or more. Further, the silicide target of the present invention having a high density can prevent the generation of particles due to pores and the generation of particles due to destruction and scattering of a brittle structure during sputtering, and ignite during processing and manufacturing steps of the target. It has a remarkable effect that it does not occur. Further, MSi _{2 of} the present invention _{. The} silicate film formed using the _x target is 1000
MSC without crystallization even at heat treatment of
Leakage current at 1.0V from the formed silicate film from _1.0 (A / cm ²⁾ is 2-4 orders of magnitude better results, the epsilon = 3.9 in the SiO ₂ film of the dielectric constant current It has an excellent effect that a value two to three times as large as that obtained is obtained.

[Procedure amendment]

[Submission date] May 11, 2001 (2001.5.1
1)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

[0020]

[Table 1]

Claims (8)

[Claims] 1. MSi _2.05-3.0 (M: Zr, H
f) a silicide target for forming a gate oxide film. 2. MSi _2.05-3.0 (M: Zr, H
f) a silicide target for forming a gate oxide film, comprising a MSi ₂ phase and a mixed phase with a Si phase. 3. The silicide target for forming a gate oxide film according to claim 2, wherein the free Si phase is 30 μm or less. 4. The silicide target for forming a gate oxide film according to claim 2, wherein the free Si phase is 10 μm or less. 5. The silicide target for forming a gate oxide film according to claim 1, wherein the relative density is 99% or more. 6. A metal hydride (M) powder and a Si powder in a ratio of 1: 2.
After preparing and mixing at a molar ratio of 0.5 to 1: 3.0, baking,
MSi characterized by sintering
_{2.05- 3.0 (M: Zr, Hf} ) for forming a gate oxide film silicide target producing method comprising a. 7. The method for manufacturing a silicide target for forming a gate oxide film according to claim 6, wherein dehydrogenation and silicidation are performed by heating during firing. 8. The method for manufacturing a silicide target for forming a gate oxide film according to claim 7, wherein the firing is performed at 600 ° C. to 800 ° C.