KR940010456B1 - Sputtering target and production thereof - Google Patents

Abstract

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Description

[Name of invention]

Sputtering Target and Manufacturing Method Thereof

[Brief Description of Drawings]

Figure 1a is a scanning electron micrograph showing the metal structure of the target according to the embodiment.

FIG. 1B is a schematic view for explaining the metallographic image of FIG. 1A.

Figure 2a is a scanning electron micrograph showing the metal structure of the target according to the comparative example and the conventional example.

FIG. 2B is a schematic view for explaining the metallographic image of FIG. 2A.

Figure 3a is a scanning electron micrograph showing the shape of the erosion surface of the target according to the embodiment.

FIG. 3B is a schematic view for explaining the surface form photograph of FIG. 3A.

4A is a scanning electron micrograph showing the shape of the erosion surface of the target according to the comparative example and the conventional example.

4B is a schematic view for explaining the surface form photograph of FIG. 4A.

5A is a scanning electron micrograph showing an enlarged view of the ridges present on the eroded surface of the target according to the comparative example and the conventional example.

FIG. 5B is a schematic view for explaining the ridge of FIG. 5A.

FIG. 6 is a scanning electron micrograph showing the result of elemental analysis of the surface of the ridge shown in FIG. 5A.

7A is a metallographic photograph of an optical microscope of a target of an example.

FIG. 7B is a schematic view for explaining the metallographic image of FIG. 7A.

8A is a metallographic photograph by an optical microscope of a target of Comparative Example.

FIG. 8B is a schematic view for explaining the metallographic image of FIG. 8A.

9A is a metallographic photograph of an optical microscope of a target of a conventional example.

FIG. 9B is a schematic view for explaining the metallographic image of FIG. 9A.

10A is a scanning electron micrograph showing the shape of the erosion surface of the target according to the embodiment.

FIG. 10B is a schematic view for explaining the shape photograph of the erosion surface of FIG. 10A.

11A is a scanning electron micrograph showing the shape of the erosion surface of the target according to the comparative example.

FIG. 11B is a schematic view for explaining a shape photograph of the erosion surface of FIG. 11A.

12A is a scanning electron micrograph showing the shape of the erosion surface of the target of the conventional example.

FIG. 12B is a schematic view for explaining the shape photograph of the erosion surface of FIG. 12A.

Detailed description of the invention

[Technical Field]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sputtering target and a method of manufacturing the same, and more particularly to a high density and high quality sputtering target used for forming a thin film of an electrode and a wiring material of a semiconductor device.

Background Technology

The sputtering method is an effective method for forming a high melting point metal silicide thin film for an electrode or a wiring of a semiconductor device. The sputtering method is excellent in mass productivity and stability of film formation, and argon ion is used for a metal silicide disk-shaped target. The target metals are released by colliding with each other, and the released metals are deposited as a thin film on a substrate facing the target plate. Therefore, the properties of the silicide thin film formed by this sputtering largely depend on the characteristics of the target.

As the sputtering target used for the formation of the high melting point metal silicide thin film, it is required to strongly reduce the amount of particles generated by high integration and miniaturization of semiconductor devices. This causes very fine particles of about 0.2 to 10 µm from the target during sputtering to enter the thin film during deposition, resulting in short circuits between the wirings after the formation of the circuit and poor wiring, resulting in a significant decrease in the manufacturing yield. This is because it is becoming a serious problem.

Conventionally, the following various manufacturing methods have been proposed as a method for miniaturizing and densifying the structure of the target in order to reduce the amount of particles generated from the target.

For example, Japanese Patent Laid-Open No. 61-179534 discloses obtaining a high-density target by a method of impregnating molten Si in a sintered body made of a high melting point metal (M) component and a Si component. In this case, the Sii matrix is spherical or elliptical, and has a structure in which MSi ₂ having a particle diameter of 5 to 500 µm is dispersed, and the impurity content of carbon or oxygen is 50 ppm or less.

On the other hand, Japanese Patent Publication No. 63-219580 discloses a mixture of a high melting point metal (M) and Si in a high vacuum to silicide reaction to form a sintered body, followed by hot isostatic press sintering. It is disclosed to obtain a high density target by the method. In this case, the microstructure has a maximum particle diameter of MSi ₂ of 20 μm or less and a maximum particle diameter of free Si of 50 μm or less. This target has a mixed structure in which fine MSi ₂ particles and free Si particles are dispersed, and the oxygen content is set to 200 ppm or less. According to this target, since the oxygen content is kept low, the sheet resistance value of film formation can be reduced.

Furthermore, in Japanese Patent Application Laid-Open No. 63-179061 or Japanese Patent Application Laid-Open No. 64-39374, a mixed powder of high melting point metal (M) and Si is subjected to silicide reaction in high vacuum to form a sintered body, and then pulverized it. By applying the composition adjusting silicide powder and hot press sintering, a target in which aggregation of Si is suppressed at a high density can be obtained.

However, in the case of the method of impregnating molten Si in the plasticized body, since molten Si is used, the impurity content such as carbon and oxygen is greatly reduced to obtain a high-density target, but the Si impregnated in the plasticized body is continuously present. Since the matrix is formed and the air holes present in the plasticized body are impregnated with Si to form a coarse and large Si part, the thermal stress generated during sputtering breaks the Si which is weaker in strength than the metal silicide. The inventors have found that the strength as a whole of the target is still insufficient because of the presence of continuously, and as a result, metal silicides are eliminated and particles are generated very much.

In addition, in the case of forming a plasticized body using the pulverized Si powder and pressing and sintering it without grinding the plasticized body as it is, a high-density target is obtained with a fine structure. Is not removed and is present in the target, so that sputter particles are not sputtered sufficiently in a large portion of carbon during sputtering, to induce particle generation, and that the carbon portion contained in the film is poor in etching property, The present inventors have found that there is a problem that causes breakage of wiring and wiring).

Furthermore, in the case of forming a sintered compact using the pulverized Si powder, and then hot pressing and sintering the sintered compact by adding a silicide powder for adjustment of composition, a high precision target is obtained from the microstructure, The present inventors have found that the amount of contamination of the raw material by carbon increases and the amount of oxygen mixed in the raw material also increases, causing the generation of particles to increase, thereby increasing the resistance by oxygen contained in the film.

On the other hand, even in the case of the high-density target whose density ratio becomes 99% or more, it can be seen that the amount of generation of particles increases due to the influence of some kind of impurities, or that defective products suddenly increase when the wiring pattern is formed by the etching process of film formation. It was confirmed by the inventors' experiment.

Conventionally, as a sputtering target of this kind, it is generally used to manufacture by the powder firing method, paying attention to the easy control of the composition of the silicide film to form. That is, the target of the conventional metal silicide is a metal silicide (hereinafter referred to as MSi ₂ ) obtained by reacting and synthesizing a metal powder (M) such as tungsten and molybdenum and a silicon powder (Si) with hot press or hot hydrostatic pressure together with Si. It is obtained by the method of pressing (Japanese Unexamined-Japanese-Patent No. 61-141673, 61-141674, 61-178474), or the method of impregnating a silicide plastic body with Si (Japanese Patent Laid-Open No. 61-58866).

However, in the former method described above, in the case of the former method, since the Si powder is added to the synthetic MSi ₂ powder to produce a sintered body, for example, in the sintered body of the composition MSi _2.2 to MSi _2.9 , the spot area ratio of the Si phase is 8-25% bar is in the range of, becomes very small compared to the MSi ₂ phase. Therefore, it is not necessarily easy to spread the Si phase evenly around the MSi ₂ particles which are obtained by pulverization evenly based on heat sintering. Accordingly, it is a target having a non-uniform tissue with a coagulation unit, such as a defect on the present focal Si between MSi ₂ are each a different size took place.

On the other hand, the melting point of the MSi ₂ phase varies greatly depending on the kind of the metal (M). For example, _{WSi 2, MOSi 2, TiSi 2} , TaSi ₂ are respectively a melting point of 2165 ℃, 2030 ℃, 1540 ℃ , 2200 ℃. Since the MSi ₂ phase having such a high melting point and the Si phase having a melting point of 1414 ° C. are pressed and sintered at or below the process temperature, sintering does not proceed between the thermally stable particles of MSi ₂ . The bond strength is weak and easy to break, and the pore remains, resulting in insufficient densification.

When the silicide film is formed by sputtering using such a target, the bonding between particles is broken by the irradiation energy of Ar ions during sputtering, and particles are generated from the sputter surface of the target by breaking and missing from the defect portion as a starting point. Done.

In particular, in high-density integrated circuits and the like, as the degree of integration increases from 4M (Mega) to 16M, the electrode width and the wiring interval become etched, and the particles mixed in the deposition film as described above drastically lower the product yield.

On the other hand, in the case of the latter conventional method described above, the composition of the target is controlled by incorporating molten Si into the silicide plasticized body controlled to a predetermined density. However, when MSi ₂ is synthesized by silicide reaction between M powder and Si powder to prepare a plasticized body having a predetermined density, or when a plasticized body having a predetermined density is prepared by sintering the press molded body using MSi ₂ powder. Since the density varies depending on the processing temperature, time, and press pressure, it is very difficult to obtain a target composition target.

Further, according to knowledge of the present inventors, because it uses a high-purity product in general, as the MSi ₂ and the Si of a raw material powder, so do gather in the impurity is diffused to the MSi ₂ phase and the boundary on the Si target MSi phase _two-phase and Si and The interfacial bond strength between the phases of MSi ₂ is in a weak state.

In addition, there is a problem that the sputtering operation becomes unstable because the difference in electrical resistance between the MSi ₂ phase and the Si phase is extremely large. In other words, the electrical resistances of WSi ₂ , MoSi ₂ , and TaSi ₂ as MSi ₂ phases were small at 70, 100, 16, and 45 µΩ, cm, respectively, while the electrical resistance of Si phase was extremely large at 2.3 × 10 ¹⁰ µΩ, cm. Since no interface layer exists at the boundary between the MSi ₂ phase and the Si phase, the electrical resistance changes rapidly at the boundary portion. In particular, the structure of the target manufactured by the latter method is in a state where the high resistance Si phase and the low resistance MSi ₂ phase are in direct contact with each other.

Therefore, in the case of sputtering using such a target, the breakdown of the MSi ₂ phase and the Si phase inevitably occurs at a certain voltage or more, and the current flows rapidly. That is, when a certain voltage or more is reached, a discharge is generated, so that a part of the MSi ₂ particles or Si phase with weak interfacial strength is dropped to form particles.

The present invention has been made in consideration of the above-described point, and an object thereof is to provide a high-quality sputtering target and a method of manufacturing the same, which can substantially prevent generation of particles and form a thin film of good quality.

[Initiation of invention]

The sputtering target according to the present invention is a metal silicide (the stoichiometric composition of MSi ₂ , where M is a metal) is bonded in a chain form to form a metal silicide phase, and the silicon phase formed by bonding silicon particles is a gap of the metal silicide phase. It is characterized by having a fine mixed structure discontinuously present in the gap and having a carbon content of 100 ppm or less.

Moreover, 400-400x10 <^4> metal silicides with a particle diameter of 0.5-30 micrometers exist in 1 mm <2> of mixed structure cross sections, and Si largest particle diameter is 30 micrometers or less. The average particle diameter of the metal silicide is 2 to 15 µm, while the average particle diameter of silicon is 2 to 10 µm. The particle diameter here is the diameter of the smallest circle circumscribed by the particle.

Moreover, the density ratio of a target is 99% or more, and content of oxygen is set to 150 ppm or less. The metal (M) of the metal silicide is at least one selected from the group consisting of tungsten, molybdenum, titanium, zirconium, hafnium, niobium, tantalum, vanadium, cobalt, chromium and nickel.

Moreover, what is necessary is just to form an interface layer in the boundary of a metal silicide and a silicon phase, In this case, the thickness of an interface layer may be set to 100-10,000 kPa. The silicon phase contains at least one element and an unavoidable element selected from the group consisting of boron, phosphorus, antimony and arsenic, and has an electrical resistivity of 0.01 to 100?, Cm.

Furthermore, in the method for producing a sputtering target according to the present invention, a metal silicide (in stoichiometric composition of MSi ₂ , where M is a metal) is bonded in a chain form to form a metal silicide phase, and a silicon phase to which silicon particles are bonded is bonded to the metal silicide phase. In the method for producing a sputtering target having a fine mixing composition discontinuously present in the gap, the carbon content of 100ppm or less,

I. mixing the metal powder (M) and silicon powder (Si) so that the Si / M atomic ratio is 2.0 ~ 4.0 to prepare a mixed powder,

II. Filling the mixing powder into a mold for molding and heating at low temperature in high vacuum to reduce carbon and oxygen;

III. Heating and mixing the powder powder under high press pressure under high vacuum to synthesize and sinter the metal silicide, and

IV. A process of densification is carried out by heating to a temperature just below the process temperature under high press pressure in a high vacuum or inert gas atmosphere.

As the metal powder M, a high purity metal powder having a maximum particle diameter of 10 mu m or less may be used, and a silicon powder having a maximum particle diameter of 30 mu m or less may be used as the silicon powder Si.

In addition, the mixed powder of the metal powder and the silicon powder is subjected to reaction melting and sintering to simultaneously perform silicide synthesis, sintering and densification.

Further, the reaction melt sintering may be performed by using a hot press method or a hot hydrostatic press method.

The present inventors analyzed the cause of particle generation of the metal silicide target of the small-bonding metal in various ways, and completed the present invention based on the knowledge obtained from the analysis result.

That is, the particles of the high melting point silicide target manufactured by the conventional powder sintering method generate abnormal discharge in the pore (air hole) portion present in the target, and therefore, the periphery of the pore is missing and thus the particles are organic. In order to make the pore as small as possible, various ideas for increasing the density of the target have been made as described above.

However, the present inventors have diligently studied the particle generation source of the high melting point silicide target, and as a result, the dropping of the erosion Si part by the action of thermal stress in addition to the particles caused by the pores, the sputter velocity between the MSi ₂ phase and the Si phase It was found that there was a missing phase of MSi ₂ by tea. That is, since high-speed Ar ions are continuously irradiated to cool the target surface heated up from the rear surface, thermal stress generated by the temperature difference in the thickness direction or thermal deformation of the target acts on the target surface. As a result, the Si phase, which is weaker in strength than the MSi ₂ phase, is destroyed and the falling pieces are particles. In particular, the eroded surface of the Si phase has a more uneven state than the MSi ₂ phase showing the smooth surface, and the protruding portion is eliminated by the action of the thermal stress or the fluctuation stress generated in the stuffer cycle, resulting in a state where particles are easily generated. have. In addition, since by the Si phase sputtering than the MSi ₂ is preferentially eroded, and if the MSi ₂ phase present in the continuous phase Si by binding on the MSi ₂ decreases as the erosion on the Si MSi ₂ phase combined alone or a plurality eliminated It becomes a particle.

Therefore, according to the mixed structure in which the fragile Si phase is refined and the fine MSi ₂ is bonded in a chain form and Si is discontinuously present in the gaps, the eroded Si portion is lost due to the action of thermal stress or the MSi ₂ phase and Si are separated. The inventors have found that particles caused by dropout of the MSi ₂ phase due to the sputter speed difference of the phases can be substantially suppressed.

In addition, the present inventors have focused on the carbon mixed in the target as another particle generating source. That is, after the sputtering operation, the eroded surface of the target was enlarged and observed, and as a result, the portion contaminated with carbon was not sputtered well, and projections remained on the eroded surface, and as a result, plasma discharge became unstable at that portion. It was found that the discharge was repeated to cause the generation of particles.

Moreover, the present inventors confirmed by experiment that the etching amount of the silicide thin film formed by the sputtering to some extent of the amount of carbon contained in a target also greatly influenced. That is, carbon is easy to produce SiC with high electrical insulation by combining with Si component. Generation of this SiC and incorporation into the formed film rapidly degrades the etching property of the formed film. That is, in order to etch the substrate on which the thin film is formed to form a circuit pattern of the integrated circuit (IC), the SiC residues are printed on the substrate coated with the photoresist with an exposure apparatus and developed with a predetermined chemical. As the remaining rate increases. As a result, the defect of a circuit pattern and the disconnection of a circuit increase rapidly.

In addition, the carbon film incorporated as a particle in the silicide film has a different light reflectance compared to other regions, and thus is easily exposed to light. Therefore, since regions with different light reflectances are formed locally on the film surface, it becomes difficult to form uniform and high precision circuit patterns.

Moreover, the inventors focused on the ridges occurring in the MSi ₂ phase and the Si phase as other particle generation sources. That is, the eroded surface of the metal silicide target manufactured by the conventional manufacturing method was observed by magnifying with a scanning electron microscope (SEM), and as a result, it was rough as shown in FIGS. 11A to 11B and 12A to 12B. It was found that a large number of minute ridges 3 exist in the large MSi ₂ phase and Si phase, and it was found that there is a close relationship between the ridges 3 and the generated particles.

As a result of further investigation, the ridge is reduced by reducing the particle diameters of the target MSi ₂ phase and Si phase, and in particular, the particle size is obtained by setting the maximum particle diameter of the MSi ₂ phase to 10 µm or less and the Si phase maximum particle diameter to 20 µm or less. It has been found that the occurrence of can be substantially suppressed.

In addition, the inventors of the present invention have conducted a thorough study to obtain a fine structure, a low carbon content, and a high density target. As a result, the mixed powder of the fine M powder and the S powder is filled into a mold for molding, which is then subjected to high vacuum. After heating, the metal silicide is synthesized by silicide reaction under a low press pressure, and then carbon and oxygen on the Si surface react at a temperature lower than 1300 ° C. at which Si evaporation becomes significant by sintering under a high press pressure. Or CO ₂ to reduce the content of carbon and oxygen, oxygen on the Si surface to reduce the content of oxygen by SiO or SiO ₂ gasification, and metal (M) to be all MSi ₂ , MSi ₂ would be combined with Streptococcus and obtained a mixed structure of Si is present discontinuously in the gaps and, in the small pores at a temperature just below the eutectic temperature And densification was completed the present invention found to be promoted.

Furthermore, an interface layer containing at least one element selected from the group consisting of boron (B), phosphorus (P), antimony (Sb) and arsenic (As) and an unavoidable element is provided at the interface between the MSi ₂ and Si phases. In addition, it has been found that particle reduction can be realized by strengthening the bonding force between phases and preventing sudden changes in electrical resistance.

Here, as the metal (M) which is a constituent of the target, molybdenum (Mo), tungsten (W), titanium (Ti), zirconium (Zr), hafnium (Hf), niobium (Nb), tantalum (Ta), and vanadium ( Metals capable of forming a metal silicide thin film having low specific resistance, such as V), cobalt (Co), chromium (Cr), and nickel (Ni), are used alone or in combination of two or more thereof, but in particular, Mo, W, Ti, Zr, Hf High melting point metals, such as Nb and Ta, are preferable.

Since these metals have a lower specific resistance and higher corrosion resistance at higher temperatures than conventional electrode wiring materials, when the silicide is used for electrode wiring of semiconductors, it is possible to speed up operations in semiconductor devices and to manufacture semiconductors. It has the advantage that it is not subjected to corrosion by chemicals or oxidation by high temperature treatment.

The sputtering target according to the present invention is characterized by uniformity of 400 to 400 × 10 ⁴ MSi ₂ phases with a particle diameter of 0.5 to 30 µm within 1 mm ₂ of the mixed tissue section by controlling three factors of particle diameter, heating temperature and press pressure of the raw material powder. be present is a mixed composition, and the microstructure is a silicon phase dispersion with a mean particle size of 2 ~ 15㎛ of MSi ₂ phase and the average particle size of 2 ~ 10㎛.

In addition, elements such as B, P, Sb, As, and inevitable elements Fe, Ni, Cr, and Al contained in the Si raw material diffuse and move to the boundary of the MSi ₂ phase and the Si phase during salicide synthesis to form an interface layer. This enhances the interfacial bonding force between the two.

The present invention has been completed based on the above knowledge.

Hereinafter, the configuration of the present invention in more detail.

When heating by applying a suitable pressure to the mixed powder of M and Si, Si is softened also the addition because they form a MSi ₂ on to react with M particulate, locally by the heat of formation of the M and the portion Si is in contact MSi ₂ It warms up and softens further. Therefore, the particles obtained by MSi ₂ agglomerating on the surface and the periphery of the MSi ₂ particles are brought into a state in which the granular MSi ₂ is bound in a chain form. When the MSi ₂ is present alone, Sii ₂ having a high sputtering speed preferentially erodes as the sputter proceeds, and MSi ₂ easily falls off. Therefore, MSi ₂ is preferably bonded in a chain form.

When the particle diameter of the MSi ₂ phase exceeds 30 µm, a ridge is formed on the upper side of the MSi _{2 in the} sputter, and particles are generated. When the particle diameter is less than 0.5 µm, the MSi ₂ phase is easily separated from the Si phase in the sputter. It is preferable that the particle size of the MSi ₂ phase is 0.5 to 30 µm, and more preferably 2 to 20 µm, since it is eliminated and causes particle generation.

If the particle size of the MSi ₂ satisfies 0.5 to 30 µm at the X value of the composition MSi _x of 2.0 &lt; X &lt; 4.0, it is preferable that 400 to 400 × 10 ⁴ MSi ₂ are present in the mixed tissue section 1 mm ² . . Furthermore, if the particle diameter is 2 to 20 µm, it is preferable that 2,000 to 300,000 MSi ₂ are present in 1 mm ² .

In addition, the size of the MSi ₂ is dependent on the particle size of the metal particles to form a metal silicide, most M particles because it exists as a cohesive state, and is formed with a MSi ₂ the particle size of the other. If the particle diameter deviation increases, the irregularities of the eroded surface increase with sputtering, and the amount of particle generation increases due to the influence of the step. Therefore, it is necessary to match the particle diameter as much as possible, and the average particle diameter of the MSi ₂ phase is It is preferable that it is 2-15 micrometers. More preferable range is 5-10 micrometers. The average particle diameter here shows the average particle diameter with respect to 100 metal silicides.

Further, as the shape of each of the MSi ₂ grains bonded to Streptococcus, it is spherical with approximately ideal. This is because the spherical shape is less likely to fall out of the mixed structure with the Si phase, and particles are likely to be generated by abnormal discharge in particles having an angled portion. From this point of view, the M particles obtained by the ion exchange method are agglomerated easily in the reduction step, and the MSi ₂ particles formed by the coalescing of the M particles have many irregularities. It is necessary to add a dispersing agent at the time of mixing, and to suppress aggregation. Or it is also preferable to use M particle | grains manufactured by the chemical vapor deposition method with favorable particle dispersibility.

The chemical vapor deposition method (hereinafter abbreviated as CVD) is used to make raw materials such as halides, sulfides, and hydrides in a gaseous state at a high temperature, and further, after performing chemical reactions such as pyrolysis, oxidation, and reduction. As a method of depositing a reaction product substrate, it is used in a wide range of fields as a method of forming a semiconductor or an insulating film.

On the other hand, since Si reacts with the M particles to form MSi ₂ while excess Si is forced to flow around the MSi ₂ particles, Si is discontinuously present in the gap between the chained MSi ₂ .

When Si is continuously present, Si is eroded more preferentially than MSi _{2 as} sputtering progresses, leading to particle dropping, and mechanical strength is low due to the action of thermal stress generated on the target during sputtering. Since the weak Si part easily breaks, it is preferable that Si is present in the gap of MSi ₂ and discontinuously in suppressing particles due to the enhancement of the strong dynamics.

If the particle diameter of Si exceeds 30 µm, the erosion of the Si erosion part occurs due to the action of thermal stress, and furthermore, ridges are formed on the Si phase in the sputter, so that particles are easily generated, so the maximum particle diameter of Si is 30 micrometers or less are preferable, More preferably, it is 20 micrometers or less.

Moreover, when the variation in the Si particle diameter becomes large, stress is concentrated in a portion having a large particle diameter, and it is easy to break due to repetition of thermal stress, so the average particle diameter of Si is preferably 2 to 10 µm, more preferably. It is good that it is 3-8 micrometers.

Particle size of the Si referred to herein is the average of the maximum length and the minimum length on the Si existing in the gaps of the MSi _2, the mean particle size of Si shows the mean particle size for the Si 100 dogs.

As the Si raw material powder, it is preferable to use a high purity product or a high purity product containing a dope agent. Impurities contained in the high-purity Si cause deterioration of device characteristics, and as few as possible are preferred. Incidentally, radioactive elements such as U and Th, which cause soft errors, are 5 ppb or less, and alkali metal elements such as Na and K, which cause mobile ion contamination, are 100 ppb or less, and Fe, Ni, Cr, etc., which are deep level impurities. The heavy metal element is preferably 1 ppm or less, the carbon causing particle generation and etching failure is 300 ppm or less, and the oxygen causing the increase in resistance is preferably 500 ppm or less.

Impurities such as carbon, oxygen, Na, and K contained in the Si powder adhere to the powder surface during the Si grinding process. The impurity-contaminated Si powder is deposited at 1200 to 1300 ° C in a high vacuum of 10 ^-4 Torr or less. Since these impurities can be reduced by heat treatment of ˜16 hr, it is preferable to use Si raw material powder subjected to heat treatment in the target production.

In general, when a target is formed using a Si raw material powder containing a dope agent, the dope agent is diffused and concentrated in a specific part such as a crystal interface during the reaction synthesis. These dope agents cause lattice disturbance or move to the boundary between the lattice distortion of the MSi ₂ phase and the Si phase to form an interface layer.

If this interface layer is present, the bonding strength of the MSi ₂ phase and the Si phase is improved, and the MSi ₂ phase is hardly eliminated from the mixed structure with the Si phase. In addition, when an interface layer having a high dope concentration is present at the boundary between the low-resistance MSi ₂ phase and the high-resistance Si phase, the abrupt change in the electrical resistance is eliminated, resulting in less occurrence of abnormal discharge during sputtering. The effect which can suppress the particle | grains induced by anisotropic discharge is anticipated.

In addition, the present inventors have conducted extensive studies to mitigate the sudden change in the electrical resistance at the boundary between the MSi ₂ phase and the Si phase, and as a result of the above-described dope agent, at least one element of B, P, Sb, As and The target obtained by sintering using an Si powder and an M powder or MSi ₂ powder containing an unavoidable element and suppressing electrical resistance has improved uniformity of electrical resistance between the MSi ₂ phase and the Si phase, resulting in uniform sputtering speed. In addition, it was found that the interface layer in which the above-described elements were diffused was formed at the boundary between the MSi ₂ phase and the Si phase, thereby making it a target having no sudden change in electrical resistance and having excellent interface strength.

Herein, B, P, Sb, and As in the dope agent are elements that have an effect of significantly lowering the electrical resistance of the Si phase. When the Si phase containing these elements is used, the electrical resistance of both phases is matched, and the sputtering speed becomes uniform. As a result, the film composition becomes stable and uniform film thickness. In addition, these elements in the Si phase diffusely move to the boundary between the MSi ₂ phase and the Si phase having large lattice disturbance or lattice distortion during sintering to form the interface layer. At this time, inevitable elements other than B, P, Sb, and As are also included in the interface layer to cause the same effect, and these elements include, for example, Fe and Ni.

Moreover, although the thickness of this interface layer changes with the quantity of the dope agent contained in Si phase, the range of 100-1000 kPa is suitable.

When the thickness of such an interfacial layer is 10,000 kPa or more, the film properties are changed by a considerable amount of dope in the Si phase, while when the thickness is less than 100 kPa, the above effects cannot be sufficiently expected. Therefore, the most preferable range is 1,000-8,000 Hz.

The thickness of this interface layer is generally detected by a high resolution secondary ion mass spectrometer (SIMS).

SIMS is a method of sputter-etching a sample with primary ions of O ²⁺ or CS ⁺ , capturing the generated secondary ions, and highly sensitively analyzing impurities in the surface layer in three dimensions. The thickness of the interface layer is determined by measuring the depth profile of the dope agent contained in the Si phase until reaching the MSi ₂ phase.

Here, the thickness of the interface layer is the distance from the inflection point located on the gentle inclined plane of the dope-made profile in Si phase to the other inflection point.

Furthermore, the resistivity of the Si phase is preferably set in the range of 0.01 to 100 Ω, cm. If the resistivity is less than 0.01 Ω, cm, the sputtering speed of Si increases and the erosion of Si causes particle generation and the desired film composition is not obtained. If the resistivity exceeds 100 Ω, cm, the above effect is sufficiently achieved. You cannot expect it. Therefore, the resistivity of the Si phase is more preferably in the range of 0.1 to 10?, Cm.

On the other hand, the portions contaminated with carbon are not sputtered well but remain as protrusions on the eroded surface, and as a result, the plasma discharge becomes unstable, and abnormal discharge is repeated to induce generation of particles. In the case where a large amount of carbon is mixed in the film, the portion is present as an etching residue at the time of forming the wiring by etching, which leads to disconnection due to poor wiring or formation of impurities, so that the content of carbon impurities is 100 ppm or less. It is necessary to suppress it, Preferably it is 50 ppm or less, More preferably, it is necessary to suppress it to 30 ppm or less. This carbon content is detected by the carbon analyzer using the combustion-infrared absorption method.

In addition, when there are many oxygen impurities in a target, since oxygen mixes in a film | membrane at the time of sputtering and increases a film resistance, it is preferable to suppress content of oxygen impurities to 150 ppm or less, More preferably, it is 100 ppm or less. This oxygen content is detected by an oxygen analyzer using an inert gas melting-infrared absorption method.

In addition, the sputtering target of the present invention is a mixed structure of a fine particle MSi ₂ phase and a Si phase, but this is from a mixed powder prepared with an M powder and a Si powder such that the X value of the composition MSi _x is 2.0 &lt; It was made to form an MSi ₂ phase by the low binding property, and it was obtained because excess Si remained around MSi ₂ phase.

That is, when an appropriate pressure is applied to the M and Si mixed powder, Si softens and reacts with M to form MSi _2. Therefore, an exothermic reaction generates MSi ₂ in the contact area between Si particles and M particles. softening even by a local temperature increase, and due to the agglomeration of the particles around on the surface and that MSi ₂ screen proceeds upset MSi _2. On the other hand, since a slightly softened large amount of unreacted Si and excess Si are forced to flow around the particles that are MSi ₂ , the MSi ₂ phase and Si phase or MSi ₂ phases are coupled by diffusion reaction. do.

Here, the reason for limiting X value in composition MSi _x to 2.0 <X <4.0 is as follows. In other words, when the X value in the composition MSi _x is less than 2.0, a large tensile stress is generated in the formed silicide film, resulting in poor adhesion to the substrate and easy peeling, while when the X value in the composition MSi _x exceeds 4.0, the sheet resistance of the film is increased. It becomes because it becomes high and unsuitable as an electrode wiring film.

Moreover, the density ratio of the target is also related to the particle generation amount, and in the case of the low density, since there are many pores in the target, abnormal discharge is likely to occur in this portion, and the discharge portion is dropped and occurs as particles, so that the density ratio of the target It is preferable that it is 99% or more in the place. Here, the density ratio (d = dt / s) is a ratio of the density (dt) of the sintered body actually measured by the Archimedes method to the theoretical density (ds) calculated from the composition ratio of the sintered body.

In addition, the present inventors have found that particle generation from the target during sputtering may occur in the processing bonding layer, surface state, or residual stress that occurs when finishing the machining such as grinding the silicide sintered body in addition to the ridges generated in the MSi ₂ phase and the Si phase. It was also found to be attributable. That is, the grinding finishing of the target conventionally performed is a processing method which scrapes a workpiece with the hard grindstone particle of the grinding grindstone rotating at high speed. In this way, when a hard and brittle material such as a silicide sintered body made of silicon silicide and silicon is ground, the chips inevitably sputter from the processing surface. According to the knowledge of the present inventors, this causes a small crack on the grinding surface due to the contact stress of the grindstone particles during grinding, and the shoulder portion of the crack is pressed by the sudden drop of stress after passing the grindstone particles. It is thought to be produced by breaking away as debris. In the processing of hard and brittle materials, the grinding depth or load of the grindstone particles is moderately increased to make cracks less likely to be contained in the local stress field induced by the grindstone particles. I'm going. Therefore, a large number of processing defect layers such as grinding traces, falling holes and microcracks are generated on the grinding surface of the silicide sintered body.

When sputtering is performed using a target having such a defect layer on the entire surface, fine particles are peeled off from the target surface by the collision of ions in the plasma, and the particles are formed as described above.

Therefore, it is desired to set the roughness Ra (centerline roughness) of the surface portion of the target to 0.05 µm or less so that the finish such that micro-cracks or defective portions generated by mechanical processing are not substantially present.

Here, the surface roughness Ra (centerline roughness) is a part of the measurement length l in the direction of the center line from the rough curve, as defined in the Hapan Industrial Standard (JIS-B0601), When the center line is the X-axis and the direction of the vertical magnification is the Y-side, and the rough curve is represented by y = f (X), the value obtained by the following formula is expressed in micrometers (µm).

In order to reduce the roughness of the finished surface and to substantially eliminate the processing defect layer in which cracks, falling holes, etc. exist, it is important to consider the processing unit to be smaller than the defect distribution of the material. Specifically, the load per grindstone particle is made small by a method such as using grindstone particles in which only small particle diameters are collected, or using a soft elastic or viscoelastic polisher. It is necessary to make the induced stress to be below the fracture stress value.

Therefore, even in a hard and brittle material such as a sintered body including a metal silicide phase, when the load is extremely small, the material exhibits only a predetermined flow deformation and there is an area where cracks do not occur, resulting in an extremely small uneven surface. You can finish with a glossy surface. As the specific method, lapping, polishing, and even mechano-chemical polishing, which are used for the purpose of ultra-precision finishing, are used as preferred methods.

Here, the Mikeno chemical polishing is a high-precision polishing method using a conventional grinding method and a chemical polishing method using the action of chemically eroding the surface of the abrasive slightly.

In practice, however, it is difficult to finish the siliceous sintered body directly to a predetermined dimension by the above processing. For this reason, it is necessary to first carry out the above-described latching and polishing processing steps in order to remove the processing defect layer generated after processing by efficient surface processing such as grinding processing.

In the surface processing method, the abrasive grains used in the order of lapping, polishing, and Mikeno chemical polishing become smaller, and thus the roughness of the finished surface is refined. By applying such a processing method to the metal silicide target, the particle generation amount is remarkably reduced. That is, according to the knowledge of the present inventors, in order to suppress the generation of particles having a particle diameter which correlates with the particle generation amount and the surface roughness and leads to the poor electrode wiring, etc., the surface roughness Ra (centerline roughness) of the processed surface It is preferable that it is 0.02 micrometer or less, and 0.05 micrometer or less is more preferable.

In addition, in sputtering by Ar ion irradiation, the laminar point of ions becomes a high stress field and is subjected to high temperature. Therefore, if the residual stress remains unevenly in the target surface layer, the stress is redistributed by the heat generated during sputtering, and the stress locally increases, causing large fragments containing several radiation fragments, resulting in an increase in particle generation. Will appear. Therefore, it is preferable that residual stress is 15 kg / mm <^2> or less from this viewpoint, More preferably, it is 5 kg / mm <^2> or less.

Next, the manufacturing method of this invention is demonstrated concretely.

The manufacturing method includes the step (I) of mixing M powder and Si powder at a predetermined ratio, the step (II) of reducing the carbon and oxygen by heating the mixed powder at low temperature, and filling the M / Si mixed powder into a molding mold. And a step (III) of synthesizing a high melting point metal silicide by silicide reaction under a low press pressure in a high vacuum in a hot press device, followed by a step (IV) of densifying and sintering under a high press pressure. In particular, the heating temperature and the press pressure in the processes III and IV are very important factors for obtaining a microstructure and a high density sintered compact.

First, the process of I in the said manufacturing method is a process of mix | blending and mixing M powder and Si powder so that a composition may make Si / M atomic ratio 2.0-4.0.

In the step of mixing the M powder and the Si powder, both powder particle diameters affect the MSi ₂ particle diameter produced by silicide synthesis and the particle diameter of the interposed SI. In order to obtain the microstructure, it is preferable to use an M powder having a maximum particle diameter of 10 m or less and a Si powder having a maximum particle diameter of 30 m or less.

Here, the reason why the X value of the composition MSi _x is limited to 2.0 <X <4.0 is that when the X value is less than 2.0, a large tensile stress is generated in the formed silicide film, resulting in poor adhesion to the substrate and easy peeling. This is because if the value exceeds 4.0, the sheet resistance of the film is increased, which is unsuitable for the electrode wiring film.

The raw material M powder and Si powder are blended so that the Si / M atomic ratio is 2.0 to 4.0, and dry mixed sufficiently uniformly using a ball mill or a V-type mixer. Uneven mixing is not preferable because the structure and composition of the target becomes uneven and the film properties deteriorate.

Here, powder mixing is preferably performed in a vacuum or in an inert gas atmosphere to prevent oxygen contamination.

In addition, as the amount of Si blended, it is suitable to mix slightly in excess of the target composition in anticipation of the loss of volatilization of Si and oxide film SiO ₂ from the surface of the Si powder when heated at high temperature. The excess is slightly less than 5%, empirically determined taking into account the temperature, time and pressure of the post process.

The process of II is a process of reducing carbon and oxygen by low temperature heating of the mixed powder combined in the process of I in high vacuum. In this step, it is important to set the heating temperature, the holding time and the vacuum degree to appropriate conditions without applying the press pressure. That is, it is preferable to set the heating temperature at 1000 to 1300 ° C. When the heating temperature is less than 1000 ° C., impurities are not sufficiently removed, while if the heating temperature is higher than 1300 ° C., the silicide reaction is performed in a state where the impurities are not sufficiently evaporated. Disclosed is a target with a high carbon and oxygen content. Therefore, it is more preferable to set heating temperature to 1100-1300 degreeC. Moreover, since the holding time is preferably set to 1 to 10 hrs in accordance with the heating temperature, if it is less than 1 hr, it is not expected to sufficiently obtain the above effect, and if it exceeds 10 hrs, the productivity deteriorates. Further, the degree of vacuum in the reactor is preferably set to a high vacuum of 10 ^-4 Torr or less, and more preferably 10 ^-4 Torr or less, in order to sufficiently reduce carbon and oxygen.

However, if the vacuum degree in the hot press device is suddenly raised, the mixed powder will be scattered from the forming mold, and the densification will be insufficient even after the process described later. Is preferred.

The step III is a step of synthesizing the MSi ₂ phase by heating the mixed powder degassed in the step II under high vacuum and low press pressure. In this silicide synthesis step, setting the heating temperature and the pressing pressure in an appropriate condition, and proceeds to a silicide reaction slowly to inhibit the growth of the MSi ₂ grains, the softened Si there is a need to flow in the gap of the MSi ₂ grains. Therefore, it is preferable to set the heating temperature to 1000 ° C to 1300 ° C. When the heating temperature is lower than 1000 ° C, the silicide reaction does not easily start. When the temperature exceeds 1300 ° C, the MSi ₂ particles grow due to the rapid silicide reaction. Rough and large. Therefore, it is preferable to set heating temperature to 1100-1300 degreeC.

At this time, the heating rate is preferably less than 20 ℃ / min for the miniaturization of the synthesized MSi ₂ phase. At the time of silicide synthesis, it is preferable to perform the atmosphere in high vacuum of 10 ^-4 Torr or less in order to control the silicide reaction rate and to prevent the impurity gas from being charged.

In addition, since the size of the press pressure affects the particle size of the MSi ₂ particles, it is preferable to set the pressure to 10 to 100 kg / cm ^2, and the heat of silicide reaction is lowered below 10 kg / cm ² , so that the softening flow of Si is reduced. While this is not performed well and becomes a non-uniform structure in which Si is segregated, when the pressure is 100 kg / cm ² or more, the contact pressure between the M powder and the Si powder increases, and the heat of generation increases due to the silicide reaction. This progresses rapidly, making the MSi ₂ particles coarse and large. Therefore, the size of the press pressure is more preferably set in the range of 30 to 60 kg / cm ² .

The atmosphere during the synthesis of the silicide is preferably performed in a high vacuum of 10 ⁻⁴ Torr or less in order to control the silicide reaction rate and prevent impurity gas from being charged.

The process of IV is a process of densifying a sintered compact by heating to high temperature just under process temperature under high press pressure in high vacuum or an inert gas atmosphere.

In this densification sintering process, press pressure, heating temperature, and holding time are important for obtaining a high density sintered compact.

The press pressure is preferably 100 to 300 kg / cm ² in order to promote densification of the sintered body. If the press pressure is less than 100 kg / cm ² , the press pressure becomes a low density sintered body in which many pores remain, while the press pressure is 300 kg / cm ² . If exceeded, it becomes a high-density sintered compact, but the molding die made of graphite easily breaks. Therefore, the size of the press pressure is preferably set in the range of 150 ~ 250kg / cm ² .

The sintering temperature (heating temperature: T) is preferably set at a temperature just below the process temperature Ts, that is, in the range of Ts-50? T &lt; Ts. Here, for example, the process temperatures Ts in the case of using W, Mo, Ti, and Ta as M are 1400, 1410, 1330, and 1385 ° C, respectively. If T is less than or equal to Ts-50, the desired high-density sintered body in which pores remain is not obtained. If T is more than or equal to Ts, the molten Si phase flows out of the mold for molding, resulting in a large sintered body.

Moreover, as for the holding time of heat sintering, 1 to 8 hours are suitable. If it is less than 1 hour, a lot of pores remain and a high-density sintered compact is not obtained, but if it becomes more than 8 hours, densification does not progress further, and the manufacturing efficiency of a target falls. This densification sintering is preferably carried out in a vacuum or inert gas atmosphere in order to prevent contamination by incorporation of impurities. However, it is not preferable because they form the Si ₃ N ₄ in a nitrogen atmosphere.

[Mode for carrying out the invention]

Next, the structure and effect of this invention are demonstrated in more detail based on the following Example.

EXAMPLES 1-12

As shown in Table 1, a high purity W, Mo, Ta, Nb powder having a maximum particle diameter of 10 µm or less and a Si powder having a maximum particle diameter of 30 µm or less were blended so as to have an Si / M atomic ratio of 2.7 and substituted with high purity Ar gas. The mixture was mixed for 48 hours in a ball mill. After filling the mixed powder into the mold for molding, it was inserted into a hot press device and degassed for 3 hours at a temperature of 1200 ° C. in 8 × 10 ^-5 Torr vacuum to reduce impurities such as carbon and oxygen. .

Subsequently, silicide synthesis and densification sintering were carried out under the conditions shown in Table 1, and the obtained sintered body was ground and polished and discharged to finish with a target having a diameter of 260 mm and a thickness of 6 mm.

[Comparative Examples 1-12]

As Comparative Examples 1 to 12, a mixed powder was prepared in which high-purity W, Ta, and Nb powders having a maximum particle diameter of 100 µm or less and high-purity Si powders having a maximum particle diameter of 200 µm or less were mixed so that the Si / M atomic ratio was 2.7. After performing the silicide synthesis and densification sintering on the conditions shown in the first table without performing the degassing heat treatment in the inside, the obtained sintered body was ground and polished and discharged to finish with a target having a diameter of 260 mm and a thickness of 6 mm.

[Prior Example 1 ~ 3]

A mixed powder obtained by mixing a high purity W powder having a maximum particle diameter of 100 μm or less and a high purity Si powder having a maximum particle diameter of 200 μm or less so as to have an Si / M atomic ratio of 2.0 was prepared, and this was 1300 ° C. in a vacuum of 2 × 10 ^-4 Torr. After heating for 4hr to form a sintered body, molten Si was combined and the sintered compact which Si / W atomic ratio was 2.7 was produced. The target of the prior art example 1 was obtained by grinding and grinding this sintered compact, and electric discharge machining, and finishing it with the target of diameter 260mm and thickness 6mm.

A high-purity W powder having a maximum particle diameter of 15 µm or less and a high-purity Si powder having a maximum particle diameter of 20 µm or less are prepared so as to have a Si / M atomic ratio of 2.7, which is 1250 ° C. in a vacuum of 8 × 10 ^-5 Torr. After heating for 4hr to form a plasticized body, the plasticized body was then filled into a sealing container for compression and sealing, which was hot hydrostatically pressed under conditions of 1180 ° C x 3hr and a pressure of 1000 atom to produce a sintered body. And the target of the prior art example 2 was obtained by grinding and grinding this sintered compact, and electric discharge machining, and finishing with the target of diameter 260mm and thickness 6mm.

A mixed powder obtained by mixing a high purity W powder having a maximum diameter particle diameter of 100 μm or less and a high purity Si powder having a maximum particle size of 200 μm or less so as to have an Si / M atomic ratio of 2.5 was prepared, which was 1300 in a vacuum of 2 × 10 ⁻⁵ Torr. After heating to 4 hr for 4 hr to form a sintered compact, the sintered compact was pulverized, and then a silicide synthetic powder was added so that the Si / W atomic ratio was 2.7, followed by hot pressing in an Ar gas atmosphere under the condition of 1380 ° C. × 3 hr. Was produced. And the target of the prior art example 3 was obtained by carrying out calculation grinding of this sintered compact, and electric discharge machining, and finishing it with the target of diameter 260mm and thickness 6mm.

The results of microscopic observation of the cross-sectional structure of the Example and Comparative Example targets are shown in FIGS. 1A, 1B, 2A, and 2B, respectively. As a result, in the structure of the target according to the comparative example, as shown in Figs. 2A and 2B, Si (2) segregates and the MSi ₂ (1) becomes rough and large. As shown in the figure, MSi ₂ (1) having a maximum particle diameter of 10 µm or less was bonded in a chain form, and showed a fine and uniform structure in which Si (2) was discontinuously present in the gap.

As a result of analyzing the contents of carbon and oxygen, in the case of the example target, carbon was 50 ppm or less and oxygen was 100 ppm or less, whereas in the comparative example target, the carbon contained about 250 ppm and the oxygen was about 1500 ppm.

Each target prepared in Examples 1 to 12, Comparative Examples 1 to 12, and Conventional Examples 1 to 3 was set in a magnetron sputtering apparatus, and then sputtered under argon pressure of 2.3 × 10 ⁻³ Torr to form a 5 inch Si wafer. The silicide film was deposited at about 3000 GPa, and the particle mixing amount was measured.

TABLE 1

As can be seen from the results shown in the first table, the amount of particles generated from the target according to the present example was very small as compared with that of the comparative example and the conventional example. In addition, the erosion surfaces of the targets of Examples, Comparative Examples and Conventional Examples were observed by scanning electron microscope (SEM), and the erosion surfaces of the Targets of Comparative Examples and Conventional Examples were shown in Figs. 4A and 4B, respectively. Although the container part 3 of was observed, the ridge was not observed in the eroded surface of the target of an Example as shown to FIG. 3A and FIG. 3B.

Moreover, the results of enlarging and observing the relatively large container portion 3 recognized on the eroding surface of the target according to the conventional example and the comparative example are shown in FIGS. 5A and 5B. Moreover, the result of elemental analysis of the surface of the container part 3 shown in FIG. 5A with the X-ray micro analyzer (XMA) is shown in FIG. As shown in Fig. 6, carbon scattered in the form of white spots on the ridge surface is observed, and this carbon is a source of particle generation.

From these results, it was demonstrated that when the target according to the embodiment is used for forming the electrode wiring of the semiconductor device, a significant improvement in the production yield of semiconductor products can be expected.

Next, a comparison of each characteristic of the target on the (example) and, if not formed (Comparative Example) In the case of forming an interface layer between the MSi ₂ phase and the Si phase constituting a target.

[Examples 101-114]

High purity W, Mo, Ti, Ta, Zr, Hf, Nb, V, Co, Cr, Ni powder and combinations thereof with an average particle diameter of 2 μm and high purity Si powder with an average particle diameter of 20 μm (B, P, Sb, As, and other unavoidable elements such as Fe and Ni) were blended at a Si / M atomic ratio of 2.6 and dry mixed for 72 hours in a ball mill substituted with high-purity Ar gas. After the mixed powder was filled into a high-purity graphite hot press mold, the mixed powder was placed in a vacuum hot press apparatus and degassed at a temperature of 1250 ° C. for 2 hours in a vacuum of 5 × 10 ⁻⁵ Torr.

Subsequently, a press pressure of 50 kg / cm ² was applied at a high vacuum of 5 × 10 ^-5 Torr, and a metal silicide (MSi ₂ ) was synthesized at 1250 ° C., and then the atmosphere in the reactor was raised to 600 Torr by adding high purity Ar gas. It sintered at 1370 degreeC for 2 hours. Then, the obtained sintered body was ground and ground, and discharged, and finished with a target having a diameter of 260 mm and a thickness of 6 mm.

[Comparative Examples 101-114]

As Comparative Examples 101 to 110, high purity W, Mo, Ti, Ta, Zr, Hf, Nb, Co, Cr, and Ni powders having an average particle diameter and high purity Si powders having an average particle diameter of 40 µm were used as Si / M atoms. After mixing so that the ratio is 2.6, under the conditions shown below,

Hot press temperature: 1380 ℃

Hot press pressure: 250kg / cm ²

Holding time: 2 hours

Atmosphere in reactor: ① up to 1250 ℃

8 × 10 ^-5 Torr vacuum

② up to 1250 ~ 1380 ℃

600 Torr Argon

It was hot pressed at, and the target by the conventional manufacturing method of diameter 260mm and thickness 6mm was obtained.

Furthermore, as Comparative Examples 111 to 114, WSi ₂ , MoSi ₂ , TaSi _2, and Ti Si ₂ powder having an average particle diameter of 80 μm were mixed with a high purity Si powder having an average particle diameter of 60 μm so as to have an Si / M atomic ratio of 2.6. It hot-pressed on the conditions similar to Comparative Examples 101-110, and obtained the target by the conventional manufacturing method of diameter 260mm and thickness 6mm.

With respect to the targets of Examples 101 to 114 and Comparative Examples 101 to 114, the average thickness, density, and tensile strength of the interface layer were measured, and the results are shown in the second table. As can be seen from this second table, since the targets of Examples 101 to 114 exhibit high density and high tensile strength, the MSi ₂ phase and the Si phase were found to be firmly bonded by the interface layer.

Moreover, the cross-sectional structure of the target of an Example, a comparative example, and a prior art example was observed with the optical microscope, and is shown to FIG. 7A-7B, 8A-8B, 9A-9B, respectively.

As a result, as shown in Figs. 7A to 7B, in this embodiment, a fine mixed structure of the MSi ₂ phase (1) and the Si phase (2) having an average particle diameter of 10 µm was shown.

8A and 8B, in the case of the target according to the comparative example, both the Si phase 2 and the MSi ₂ phase 1 become rough and large. As shown in Figs. 9A and 9B, it was confirmed that the Si phase 2 and the MSi ₂ phase 1 became rough and large in the target of the conventional example, so that the particles were easily formed.

In addition, after setting each target prepared in Examples 110-114 and Comparative Examples 101-114 in a magnetron sputtering apparatus, sputtering was carried out under the conditions of 2.3 * 10 <^-3> of argon pressure, and a silicide film | membrane was formed on a 5-inch Si wafer. It deposited in 3000 microseconds and measured the particle mixing amount is shown in the 2nd table | surface.

TABLE 2

As can be seen from the results shown in the second table, the amount of particles generated from the target of this example was very small.

In addition, the spurts of the targets of Examples, Comparative Examples and Conventional Examples were observed by scanning electron microscopy (SEM), respectively. FIGS. 10A to 10B, 11A to 11B, 12A to 12B, respectively. The metal conditions shown in the figure were observed. That is, no ridge 3 was observed on the sputtering surfaces of the comparative examples (FIGS. 11A and 11B) and the conventional examples (FIGS. 12A and 12B). From this result, it was demonstrated that a significant improvement in yield can be expected when the target of the present invention is used for the formation of electrode wiring of a semiconductor device.

Next, the influence of the processing defect layer, the surface state, and the residual stress on the generation of particles generated when the silicide sintered body constituting the target is finished by machining such as grinding is confirmed by the following examples.

Example 200

After cutting the silicide sintered body (tungsten silicide) into a diameter of 260 mm by wire discharge machining, the grinding wheel SD27DJ55BW6 and the grinding wheel rotation speed 1200m / min were used using a verical axis rotary planar grinding machine. The grinding was carried out to a thickness of 6 mm under conditions of a table rotational speed of 12 rpm and a grinding speed of 10 µm / min to be a target.

Subsequently, after soldering the backing plate to the machined surface, the grinding surface was lapping with 60hr of diamond grindstone particles 15µm and 10hr of grindstone particles 3µm using a lens polisher and attached to the wrapping surface with an ultrasonic cleaner. The working solution was removed and then acetone degreased and dried to finish.

As a result of observing the obtained processed surface with a scanning electron microscope (SEM), the grinding scars and the dropping holes formed by the grinding process did not remain, and many microcracks generated by the deformation fracture action of the abrasive grindstone particles. It was also not recognized, and it was confirmed that the processing defect layer was removed.

In addition, the residual stress was measured by a surface roughness method using a surface roughness measuring instrument (Talysurf) using a roughness measurement of the machined surface and an X-ray stress measuring apparatus. The results are shown in the third table. Moreover, the measurement result about the as-grinded state was also written in the 3rd table | surface as the comparative example 200.

After setting this target in a magnetron sputtering apparatus, sputtering by Ar ion irradiation was carried out, and the silicide film was deposited by 3000 Å on a 5-inch Si wafer. The amount of particles incorporated into the film was measured and the results are shown in Table 3 below. Also, as can be seen from the third table as a comparative example 200 of the sputtering result of the grinding surface, the amount of particles in the film formed by the target according to Example 200 is greatly reduced, and the amount of particles generated during sputtering by lapping. It has been found that can be reduced.

Example 201

After grinding and lapping the silicide sintered body having a diameter of 260 mm in the same manner as in Example 200, using 0.3 μm of cerium oxide grindstone particles and acrylic resin polisher, the polisher pressure was 1 kg / cm ² and the polisher speed was 10 m / min. The target was finished by carrying out acetone degreasing and drying after removing the processing liquid by ultrasonic cleaning with 10-hr polishing processing under conditions.

As a result of observing the obtained working surface by SEM, processing defect layers such as grinding marks, dropping holes and microcracks generated by grinding were completely lost and finished in a mirror surface state. In addition, the measurement results of the surface roughness and residual stress of the machined surface are shown in the third table. Compared to the grinding surface of Comparative Example 200, the surface irregularities are extremely small, and the plastic or elastic distortion of the surface layer caused by the grinding is Almost removed.

Magnetron sputtering was performed using this target, and a silicide film was formed on a 5-inch Si wafer. The measurement result of the particle amount mixed in this film | membrane is shown in the 3rd table | surface. As can be seen from the results, when polishing was performed as the final finish, it was found that the particles generated from the target were greatly reduced by the improvement of the surface state.

Example 202

After grinding and lapping a silicide sintered body having a diameter of 260 mm in the same manner as in Example 200, using a powder of 0.02 μm SiO and a cross polisher under conditions of a polisher pressure of 1 kg / cm ² and a polisher speed of 10 m / min 20hr Mikeno chemical polishing was performed, and the target was finished by acetone degreasing and drying after ultrasonic cleaning.

As a result of SEM observation of the obtained processed surface, the processing defect layer which generate | occur | produced by the grinding process was not recognized. In addition, compared with the surface roughness and residual stress of the machined surface, the smoothness was much higher, and the machined surface was not deformed into the distortion-free surface.

Using this target, magnetron and sputtering were carried out to form a silicide film on the 5-inch Si wafer, and the amount of particles mixed in the film was measured. As shown in Table 3, the particles were hardly recognized. As a result, it was confirmed that the processed bonding layer, which is a source of particles, and the residual stress can be completely removed.

TABLE 3

Industrial availability

According to the sputtering target according to the present invention and a method for manufacturing the same, a target having a high density and high strength microcondition that can substantially prevent particle generation is obtained, and therefore a high quality thin film for electrode and wiring material of a semiconductor device can be formed. Very useful when

Claims (13)

Metal silicides (MSi _{2 in the} stoichiometric composition, where M is a metal) are bonded in a chain to form a metal silicide phase, and a silicon phase formed by bonding silicon particles has a fine mixed structure discontinuously present in the gap of the metal silicide. And a sputtering target, wherein the carbon content is 100 ppm or less. The sputtering target according to claim 1, wherein 400 to 400 x 10 ⁴ metal silicides having a particle diameter of 0.5 to 30 µm are present in the mixed tissue cross section 1 mm ² , and a maximum particle diameter of Si is 30 µm or less. The sputtering target according to claim 1, wherein the average particle diameter of the metal silicide is 2 to 15 µm, and the average particle diameter of silicon is 2 to 10 µm. The sputtering target according to claim 1, wherein the density ratio is 99% or more. The sputtering target according to claim 1, wherein the content of oxygen is 150 ppm or less. The sputtering target of claim 1, wherein the metal of the metal silicide is at least one metal selected from the group consisting of tungsten, molybdenum, titanium, zirconium, hafnium, niobium, tantalum, vanadium, cobalt, chromium and nickel. The sputtering target according to claim 1, wherein an interface layer is formed at the boundary between the metal silicide phase and the silicon phase. 8. The sputtering target according to claim 7, wherein the thickness of the interfacial layer formed at the boundary between the metal silicide phase and the silicon phase is 100 to 10,000 mW. The sputtering target according to claim 1, wherein the silicon phase contains at least one element and an unavoidable element selected from the group consisting of boron, phosphorus, antimony and ratio, and has an electrical resistivity of 0.01 to 100 Ω · cm. Metal silicides (with stoichiometric composition MSi ₂ , where M is a metal) are bonded in a chain to form a metal silicide phase, and a silicon phase formed by bonding silicon particles has a fine mixed structure discontinuously present in the gap of the metal silicide, In the method for producing a sputtering target, characterized in that the carbon content is 100ppm or less, I. Process for preparing a mixed powder by mixing the metal powder (M) and silicon powder (Si) so that the Si / M atomic ratio is 2.0 ~ 4.0 and , II. Filling the mixed powder into a mold for molding and heating at low temperature in high vacuum to reduce carbon and oxygen; III. A process of synthesizing and sintering a metal silicide phase by heating under high press pressure under high vacuum, and IV. A method for producing a sputtering target, comprising the step of densifying by heating to a temperature just below the process temperature under a high press pressure in a high vacuum or inert gas atmosphere. 11. A high purity metal powder having a maximum particle diameter of 10 mu m or less as a metal powder (M), and a high purity silicon powder having a maximum particle diameter of 30 mu m or less as a silicon powder (Si). Method for producing a sputtering target. The method for producing a sputtering target according to claim 10, wherein the mixed powder of the metal powder and the silicon powder is subjected to reaction melting and sintering to simultaneously perform silicide synthesis, sintering, and densification. The method for producing a sputtering target according to claim 12, wherein the reaction melt sintering uses a hot press method or a hydrostatic press method.