JP2017179554A - Low particle metal silicide sputtering target, and production method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sputtering target having a MoSiphase dispersion in a Si parent phase and having a MoSiphase dispersion structure capable of effectively suppressing a particle generation during sputtering.SOLUTION: A sputtering target having a MoSi2 phase in a Si parent phase is made to have an organization structure, in which the maximum diameter capable of existing in a region having no MoSiphase existing is 9.0 μm or less, in which the maximum diameter of a MoSiis 15 μm, and in which the mean diameter of the MoSiphase is 13 μm or less.SELECTED DRAWING: Figure 3

Description

The present invention relates to a sputtering target in which a MoSi ₂ phase, which is a compound of molybdenum (Mo) and Si, is uniformly dispersed in a silicon (Si) phase, which is a parent phase, and a method for manufacturing the same. Sputtering target in which the number of particles during sputtering is reduced by dispersing the MoSi ₂ phase finely and uniformly without forming coarse aggregates, and raw material processing effective for producing such a sputtering target The present invention relates to a manufacturing method including steps.

  The metal silicide material is a material used in various parts and applications such as a material for a gate electrode of a field effect transistor (MOSFET), a material for a power semiconductor, and a material for a light shielding film of a mask blank. In these applications, thinned metal silicide is used. Since metal silicide is generally a high-melting-point material, sputtering is performed using a sputtering target containing the target material material of the metal silicide in the target elemental composition ratio. In many cases, a thin film is formed.

Of these, a metal silicide material having an atomic ratio of M / Si = 2.0 to 3.0 (M: metal element) is often used for a gate electrode of a complementary MOS (CMOS) circuit. When a silicide film is formed by sputtering, a sputtering target made of a material having a composition with an atomic ratio of about M / Si = 2.0 to 3.0 is used. Patent Document 1 discloses, as an example of such a sputtering target, a sputtering target having a MoSi ₂ phase in which the target structure is a silicide of Si phase, molybdenum, and Si, as described above. In the elemental composition range, the MoSi ₂ phase occupies most of the sputtering surface and has a structure in which the Si phase is interspersed therebetween.

  A large-scale integrated circuit (LSI) or the like of a semiconductor device including a CMOS circuit as described above is formed by sequentially stacking and patterning wirings, electrodes, insulating layers, and the like on a semiconductor substrate. The formation of a layer having a specific pattern shape is formed by etching unnecessary portions other than the desired pattern shape in order to form a mask layer or a passivation layer corresponding to the pattern. It is formed using a lithography technique using an exposure mask having the above shape. An exposure mask (photomask) used for lithography is formed by patterning a thin film having a property of blocking (reflecting) light on a substrate that transmits light used for exposure.

  Patterning of exposure masks used in lithography for semiconductor manufacturing is performed by etching a light-shielding thin film formed on the surface of a substrate, but it becomes a basis for forming a desired pattern. The mask substrate in a state where is formed is referred to as a (photo) mask blank. Metal silicide materials such as Mo silicide and tungsten (W) silicide have appropriate optical characteristics with respect to the exposure wavelength of ArF excimer laser and the like, and are conventional with respect to substrate materials such as quartz and silicate glass. Since it has better adhesion characteristics than Cr-based thin film materials, it is also suitably used as a light-shielding thin film material for photomasks. In particular, the silicide of Mo is formed as a film that is semi-transparent to the light source for exposure, thereby shifting the phase of the light transmitted through the thin film portion and diffracting the boundary portion between the transmissive portion and the semi-transmissive portion. It can be used as a phase shift layer of a halftone mask for emphasis, that is, higher resolution. Further, the silicide of Mo can be used as a light shielding layer of a normal binary mask by combining the composition, film thickness, and other laminated films.

Such a Mo blank for a mask blank is generally formed by sputtering a sputtering target containing a silicide raw material at a desired elemental composition ratio. A Mo silicide material having Mo / Si = 3.0 to 15.0 is often used. In the case of the Mo / Si composition in such a range, in contrast to the above-described sputtering target for forming the gate electrode, a structure in which the Si phase is a mother phase and the MoSi ₂ phase is interspersed and dispersed therebetween. It is known (see Patent Document 2 and Patent Document 3). However, when the Mo silicide layer is formed by sputtering, it is a common technical problem to suppress the generation of particles during sputtering regardless of the target structure.

In the target structure of Patent Document 1 described above, the MoSi ₂ phase occupies most of the sputter surface, and the scattered Si phase forms an erosion surface in a form that collapses from the speed of the sputter rate. It is thought that particles are generated due to peeling of the film redeposited on the stepped portion, damage due to micro arcing, and the like. Since this phenomenon is the same in the voids in the case of a low density sintered body, the target itself is required to have a high density in order to suppress the generation of particles. In the target structure as described in Patent Document 2 or 3, the Si phase occupies most of the sputtering surface and the MoSi ₂ phase is scattered, and the Si phase having a high sputtering speed is first thinned. Erosion proceeds in such a way that the slow-moving MoSi ₂ phase is left behind and scattered. Therefore, in addition to the cause of generation of particles due to the same reason as the structure of Patent Document 1, the tip of the MoSi ₂ phase left behind by erosion becomes sharp and this becomes the starting point of micro arcing, or the MoSi ₂ phase itself is the surrounding Si. It is necessary to take a countermeasure in consideration of the particle generation factor peculiar to this structure, such as desorption from the phase to become a particle generation source.

In Patent Documents 2 and 3, by increasing the density of the target, the maximum particle diameter of the MoSi ₂ phase existing in the target structure is set to 20 μm or less, and the coarse MoSi ₂ particles are not included. It corresponds to. In addition, in Patent Document 2, the number of MoSi ₂ phase particles per unit area on the sputtering surface is set to a specific number or more, specifically about 20 to 120 per 0.01 mm ² , thereby generating particles. Trying to suppress.

However, even if coarse particles are not included in the target and a predetermined number of MoSi ₂ phase particles are included per unit area, the degree of uniformity that the MoSi ₂ particles are dispersed in the target structure is substantially reduced. It is not specific. If MoSi _two- phase particles are present unevenly in the Si base phase, arcing is likely to be induced at the location, which not only leads to the generation of particles, but also to the composition uniformity of the layer to be deposited. Adversely affect. Therefore, in order to further suppress the generation of particles, it is necessary to consider more uniformly dispersing the MoSi _two- phase particles in the target structure. It has not been described until a detailed study is performed from such a viewpoint.

  Further, Patent Documents 4 and 5 disclose that a sputtering process is performed at the time of sputtering by devising process means and conditions such as target arrangement at the time of sputtering deposition of the Mo silicide layer used for the mask blank and gas used for sputtering discharge. A technique for preventing the generation of particles is disclosed. However, these do not describe details regarding the structure of the sputtering target used. If a sputtering target used in the techniques of these documents can suppress the generation of particles during sputtering by controlling the structure of the target, the generation of particles during the formation of the Mo silicide layer can be more effectively prevented. Can be considered useful.

  In recent years, the characteristics related to particles and pinholes required for the light shielding layer and phase shift layer of mask blanks have become increasingly severe along with miniaturization of circuit patterns and shorter exposure wavelengths. . In particular, coarse particles have a local effect on the light shielding property of the circuit pattern after the circuit pattern is formed by etching and the phase of the semi-transmitted light. Therefore, a mask blank containing such particles in the Mo silicide layer has recently been used. It cannot be used in highly refined processes. Therefore, the generation of particles must be eliminated as much as possible when the light shielding layer and the phase shift layer of the mask blank are formed by sputtering.

Japanese Patent No. 3707622 Japanese Patent No. 4135357 Japanese Patent No. 4509363 Japanese Patent No. 4336206 JP2015-067884

In view of the above problems, the present invention provides a sputtering target having a MoSi ₂ phase dispersion structure capable of effectively suppressing the generation of particles during sputtering in a sputtering target having a structure in which a MoSi ₂ phase is dispersed in a Si matrix. For the purpose. In addition, another object of the present invention is to provide a target manufacturing method effective for realizing the structure of such a sputtering target.

In order to solve the above problems, the present inventor has conducted intensive research. As a result, the present inventors have studied the particle size of MoSi _two- phase particles dispersed in the Si matrix of the target, the number present per unit area, and by appropriately specifying the size of the parent phase space interposed between MoSi ₂ phase particles, the uniformity of dispersion of the MoSi ₂ phase particles also controlled within a proper range, the generation of particles by identifying them It was found that a target with a small amount can be obtained.

Based on such knowledge, the present invention provides the following inventions.
1) A sputtering target having a MoSi ₂ phase in a Si matrix, wherein the maximum diameter of a circle that can exist in a region where the MoSi ₂ phase does not exist is 9.0 μm or less, and the maximum diameter of the MoSi ₂ phase is A sputtering target characterized in that the average diameter of the MoSi ₂ phase is 13 μm or less,
2) In the sputtering surface of the sputtering target, the number density of the MoSi ₂ phase having a particle diameter of 0.35 μm or more is 1 × 10 ⁴ mm ⁻² or more. target,
3) The sputtering target according to 1) or 2) above, wherein the relative density is 99% or more,
4) The sputtering target according to any one of 1) to 3) above, wherein the total of Al, Cu, Fe, K, Na, Ni, W and Zr is 2000 ppm or less.
5) The sputtering target according to any one of 1) to 4) above, wherein the sputtering target as a whole has a Si / Mo atomic ratio of 3.0 to 15.0.
6) The sputtering target according to any one of 1) to 5) above, which is used for producing a light shielding film of a mask blank or a phase shift film,
7) The method for producing a sputtering target according to any one of 1) to 6), wherein a Si raw material powder having an average particle diameter of 1 to 50 μm is prepared, and a MoSi ₂ raw material powder having an average particle diameter of 1 to 50 μm Preparing the Si powder and the MoSi ₂ powder using a multiple agitating blade rotating medium agitating mill for 0.5 to 6 hours, mixing the pulverized and mixed mixed raw material powder by hot pressing A process for producing a sputtering target, characterized by comprising:
8) The step of pulverizing and mixing in the multiple stirring blade rotating medium stirring mill is carried out at a rotational speed of 50 to 400 rpm for 0.5 to 10 hours. Production method,
9) The method for producing a sputtering target according to any one of 1) to 6), wherein a Si raw material powder having an average particle diameter of 1 to 50 μm is prepared, and a MoSi ₂ raw material powder having an average particle diameter of 1 to 50 μm A step of pulverizing only the MoSi ₂ powder with a jet mill, a step of pulverizing and mixing the pulverized MoSi ₂ powder and the Si powder with a vibration mill, and hot mixing and mixing the mixed raw material powder. A method for producing a sputtering target, comprising a step of sintering by pressing,
10) The sputtering according to any one of 7) to 9), wherein the sintering is performed in a vacuum atmosphere by hot pressing at a temperature of 800 to 1400 ° C. and a surface pressure of 150 to 400 kgf / cm ^2. Target manufacturing method.

The sputtering target of the present invention is a structure in which MoSi ₂ phase particles are dispersed in a Si matrix phase, and does not include coarse MoSi ₂ phase particles or aggregates, and the structure in which MoSi ₂ phase particles are uniformly dispersed in the structure. Therefore, the generation of particles during sputtering can be effectively suppressed, and high uniformity of thin film characteristics can be expected. Furthermore, according to the manufacturing method of the sputtering target of this invention, the structure of the sputtering target of the structure mentioned above can be implement | achieved effectively. These are useful as sputtering targets for thin film production in fields where high-definition thin film patterns such as mask blanks are required.

Schematic diagram of circles and silicide phase grain size that can be set in the target structure where no silicide phase exists Location where target structure observation is performed in the present invention Example of SEM observation tissue image of Example 1 Example of SEM observation tissue image of Example 2 Example of SEM observation tissue image of Comparative Example 1 Example of SEM observation tissue image of Comparative Example 2

The sputtering target of the present invention has a MoSi ₂ phase in the Si matrix as the target structure. Such a structure can be easily identified by an enlarged image of the surface of the target using a scanning electron microscope (SEM), a metal microscope, or the like. Here, “having an MoSi ₂ phase in the Si matrix” refers to a form in which particles of the MoSi ₂ phase are dispersed and present in the Si matrix that is typically a matrix. However, in the present invention, as the form of the dispersed dot, first, it is specified that the maximum diameter of a circle that can exist in a region where no silicide phase exists is 6.5 μm or less.

The above-mentioned “maximum diameter of a circle that can exist in a region where no silicide phase exists” means that, in a predetermined Si matrix region 101 in the observation image, in an observation location on the target surface, as schematically shown in FIG. When a circle in contact with the outer edge of the closest MoSi _two- phase particle 102 in this region is set, it means the maximum diameter (R _max ) that can be set. The number of observation points should be set evenly on the sputtering surface of the target in consideration of the uniformity of the dispersion of the MoSi _two- phase particles, but an enlarged image should be observed without omission over the entire sputtering surface of the target. In the present invention, as shown in FIG. 2, in the present invention, when the target radius is r, the r / 5 position and the 4r / 5 position are 90 in the circumferential direction. Observation was made at a total of nine positions of eight points that were evenly divided at intervals, and the maximum diameter of each circle was determined at each of the nine positions. The maximum diameter of a circle that can exist in

The observation field at that time should be set to an appropriate range in which a sufficient number of particles can be confirmed in the field of view and the diameter of the circle can be evaluated with appropriate accuracy from the observation image. It is clear. If the observation field is too narrow, the dispersion structure of the particles in the target may not be sufficiently reflected in the field of view, and if the observation field is too wide, the observation image of individual particles and interparticle spaces will be reduced, resulting in It becomes difficult to accurately assess the size. As a preferable evaluation visual field range, a rectangular region of 50 to 500 μm × 50 to 500 μm can be mentioned, and in the present invention, observation is performed with a 190 × 190 μm ² visual field considered to be adequately appropriate for calculation of the evaluation value. However, it is not limited to this.

The maximum diameter of a circle that can exist in a region where the target silicide phase does not exist is one evaluation value that serves as an index of the degree of uniformity of the MoSi _two- phase particle dispersion on the sputtering surface of the target. As this value increases, there is a region on the sputtering surface of the target where no MoSi _two- phase particles exist and only the Si phase of the mother phase exists widely, which means that the MoSi _two- phase particles are aggregated or unevenly distributed. It also serves as a guideline to show that Therefore, the sputtering target of the present invention specifies that this numerical value is 9.0 μm or less. When this numerical value exceeds 9.0 μm, arcing and abnormal discharge are likely to occur due to the influence of the agglomerated or unevenly distributed MoSi _two- phase particles, which causes an increase in particles generated during sputtering. The maximum diameter of a circle that can exist in the region where the target silicide phase does not exist is preferably 8.0 μm or less, and more preferably 6.5 μm or less.

As described above, the maximum diameter of a circle that can exist in a region where there is no silicide phase of the target is one of the indicators of the degree of uniformity of MoSi ₂ phase particle dispersion on the target sputtering surface. However, it is not sufficient as a value for evaluating the uniformity of the dispersion of the MoSi _two- phase particles on the sputtering surface of the target. Therefore, in the present invention, the range of the maximum diameter of the MoSi ₂ phase, are identified together with the range of the average diameter of the MoSi ₂ phase. The term “maximum diameter of MoSi ₂ phase” as used herein refers to the MoSi ₂ phase particle diameter defined as the diameter when assuming a circle of the same area with respect to the area of the MoSi ₂ phase particles surrounded by the Si matrix. Of these, the value refers to the largest of the observed fields of view. The area of the MoSi _two- phase particles can be determined by pixel analysis using image analysis software. The “average diameter of MoSi ₂ phase” is a value that refers to the particle diameter (median diameter) at which the distribution becomes 50% when the integrated distribution of the MoSi ₂ phase particle diameter defined above is taken. .

The maximum diameter of the MoSi ₂ phase in the target is an indicator of the presence or absence of coarse aggregates of MoSi ₂ phase particles present in the target structure, and the present invention specifies that this is 15 μm or less. MoSi ₂ phase particles exceeding this value are considered to be coarse aggregates formed by agglomeration of fine MoSi ₂ phase particles, which causes an increase in particles generated during sputtering. The maximum diameter of the MoSi ₂ phase is preferably 10 μm or less, and more preferably 8.5 μm or less.

Furthermore, in the target tissue over which coarse aggregates of MoSi ₂ phase particles are not present, it is necessary that the diameter of each of the MoSi ₂ phase particles also those fine average. The average diameter of the MoSi ₂ phase in the target is one index that the average diameter of the individual MoSi ₂ phase particles is fine, and in the present invention, this is specified to be 13 μm or less. . Exceeding this value means that the MoSi _two- phase particles present in the parent phase are coarse on average, which causes an increase in particles generated during sputtering. The average diameter of the MoSi ₂ phase is preferably 8 μm or less, and more preferably 7 μm or less. In addition, both the maximum diameter and the average of the MoSi ₂ phase particles are observed in the same places as in the case of evaluating the maximum diameter of a circle that can exist in a region where the MoSi ₂ phase does not exist.

The number density of MoSi ₂ silicide phases in the sputtering surface of the sputtering target of the present invention is preferably 1 × 10 ⁴ mm ⁻² or more. This “silicide phase number density” represents the number of MoSi _two- phase particles having a particle diameter of 0.35 μm or more in a unit area. If this value is small, the Mo composition becomes extremely small and good. There is a risk that a silicide layer having such characteristics cannot be formed. The number density of the MoSi ₂ silicide phase is more preferably 2 × 10 ⁴ mm ⁻² or more. Evaluation of the number density of the MoSi ₂ silicide phase is also performed from an enlarged observation image of the target surface. In this case as well, a sufficient number of particles can be confirmed in the field of view, and the number of MoSi ₂ silicide phases can be confirmed with appropriate accuracy from the observation image. It is clear that observation should be performed by setting an observation field that can be recognized and evaluated. As described above, a rectangular area of 50 to 500 μm × 50 to 500 μm can be mentioned as a preferable evaluation visual field range, but in the present invention, observation is performed by setting a visual field of 190 × 190 μm ² , but it is limited to this. It is not something.

Moreover, it is preferable that the relative density of the sputtering target of this invention is 99.0% or more. As described above, when the relative density of the target is low, voids existing in the target structure are exposed to the sputtering surface as the erosion progresses, and this part causes arcing and abnormal discharge, which increases the generation of particles during sputtering. Become. Therefore, it is preferable that the relative density of the target is high, and it is more preferably 99.5% or more, and further preferably 99.9% or more. The relative density in this invention is shown by the ratio with respect to the theoretical density of Si-Mo of the measured evaluation density of Si-Mo evaluated by Archimedes method, as represented by the following formula | equation.
Formula: Relative density = (Archimedes density / theoretical density) × 100 (%)
Here, the theoretical density of the Si-Mo is the ratio of Mo atoms in the target as X (%), further Si density and atomic weight, respectively [rho _Si and _Z Si, the density and molecular weight, respectively [rho _MoSi2 of MoSi ₂ In the case of Z _MoSi2 , it is expressed by the following formula.
Formula: Theoretical density = {Z _Si × (100−3X) + Z _{MoSi 2} × X} / {(100−3X) × Z _Si / ρ _{Si i} + X × Z _{MoSi 2} / ρ _{MoSi 2} }
As represented by this equation, the theoretical density calculation assumes an ideal structure in which the target is composed of two phases of Si and MoSi ₂ . In the present invention, values of ρ _Si = 2.33 g / cm ³ , Z _Si = 28.09, ρ _{MoSi 2} = 6.24 g / cm ³ , and Z _{MoSi 2} = 152.12 are used for the density and atomic / molecular weight of each phase. Is used.

Needless to say, it is not preferable that the impurity element remains in the target because it is taken in as an impurity in the silicide layer to be formed. In the sputtering target of the present invention, the total of Al, Cu, Fe, K, Na, Ni, W and Zr, which are main impurities in Si and MoSi ₂ , is preferably 2000 ppm or less, more preferably 1000 ppm or less, More preferably, it is 100 ppm or less, Most preferably, it is 50 ppm or less.

  The sputtering target of the present invention preferably has a Si / Mo atomic ratio of 3.0 to 15.0 in the entire target, and a Mo silicide layer having such a Si / Mo composition range is formed at the time of sputtering. It can be formed while reducing the generation of particles. As described above, a Mo silicide layer having a Si / Mo atomic ratio in the range of 3.0 to 15.0 is often used as a light shielding film or a phase shift film in a mask blank. In addition, the light shielding film and the phase shift film of the mask blank must be ones in which particles are excluded as much as possible. Therefore, the sputtering target of the present invention can be suitably used for forming a light shielding film or a phase shift film for a mask blank. From a practical viewpoint, the Si / Mo atomic ratio is preferably 15 or less, and more preferably 10 or less. Also regarding the lower limit, the Si / Mo atomic ratio is preferably 3 or more, and more preferably 5 or more.

  The sputtering target of the present invention does not particularly limit the manufacturing method, and any means may be applied as long as the above-described characteristics can be imparted to the target. However, as a method that can effectively achieve the above-described target characteristics, a manufacturing method by sintering including a step of strongly crushing and stirring the raw material phase can be suitably applied as shown below.

First, Si raw material powder having an average particle diameter of 1 to 50 μm and MoSi ₂ raw material powder having an average particle diameter of 1 to 50 μm are prepared as raw materials for the sputtering target. The Si raw material powder becomes the basis of the Si parent phase in the sputtering target after sintering, and the MoSi ₂ raw material powder becomes the basis of the MoSi ₂ phase particles dispersed therein. In order to obtain a sintered body structure in which the MoSi _two- phase particles are uniformly finely dispersed in the Si matrix, these raw material powders are preferably pulverized and mixed in a multiple stirring blade rotating medium stirring mill. This type of medium agitating mill, also called an attritor, is made powerful by rotating a plurality of agitating blades (agitating pins) protruding from a rotating shaft, with the raw material powder and the grinding medium filled in the container. The pulverization and mixing are performed, and the effect of obtaining a fine and uniform mixed powder is higher than that of a general ball mill in which a raw material powder is pulverized and mixed with a medium by rotating a drum-shaped container.

When pulverizing and mixing Si raw material powder and MoSi ₂ raw material powder with a multiple stirring blade rotating medium stirring mill, processing is performed under conditions such as a rotational speed of 50 to 400 ppm and a processing time of 0.5 to 10 hours using a ceramic medium. Preferably it is done. Further, the pulverization and mixing steps described above may be performed using other means as long as a desired pulverization and mixing state can be obtained. For example, the raw material powder may be pulverized and mixed by a vibration mill under appropriate conditions, and the mixed raw material powder for sintering may be obtained by further classifying the mixed powder.

Next, the obtained mixed raw material powder is filled into a mold having a predetermined shape, and hot pressing is performed to form a sintered body. Hot pressing can be performed in a vacuum atmosphere under conditions of a temperature of 800 to 1400 ° C. and a surface pressure of 150 to 400 kgf / cm ² . If the temperature and pressure are lower than this, it becomes difficult to form a sintered body having a sufficient density, and if it is higher than this, coarse grain growth occurs during sintering, and MoSi _two- phase particles are uniformly and finely dispersed. Since it becomes difficult to obtain an organization structure, it is not preferable. The obtained sintered body may be taken out of the mold and subjected to processing such as cutting as necessary in order to obtain a sputtering target.

  If the above-mentioned technical means and the range of manufacturing conditions, or specific examples in the examples described later, are also referred to, the sputtering conditions having the characteristics of the present invention are excessively adjusted by appropriately adjusting the manufacturing conditions as necessary. It will be apparent to those skilled in the art that it can be manufactured without trial and error.

  The present invention will be specifically described based on examples and comparative examples. The descriptions of the following examples and comparative examples are only specific examples for facilitating understanding of the technical contents of the present invention, and the technical scope of the present invention is not limited by these specific examples.

Example 1
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. These two raw material powders were put into a stirring vessel of a medium stirring mill together with a zirconia medium so that the atomic ratio of Mo / Si = 6.7, and the treatment was performed for 4 hours. The obtained mixed raw material powder was filled in a graphite mold and hot pressed in a vacuum atmosphere at a temperature of 1300 ° C. and a surface pressure of 300 kgf / cm ² to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

About the sputter | spatter surface of the obtained sputtering target, the structure | tissue image observation was performed using the scanning electron microscope. FIG. 3 is an example of a tissue image by SEM observation observed in Example 1. As can be seen from this structure image, the target structure is uniformly and finely formed without the formation of coarse aggregates in the MoSi ₂ phase particles observed in white in the matrix phase composed of Si observed in black. A distributed structure is shown. It is confirmed by analysis by energy dispersive X-ray spectroscopy (EDX) that the portion observed black in the structure image is made of Si and the portion observed white is made of MoSi _two- phase particles. Tissue images are observed in a total of nine locations, the center of the target, and eight points divided equally at 90 ° intervals in the circumferential direction at r / 5 and 4r / 5 where r is the target radius. Went in the position. These results, the maximum diameter of the circle that can be present in a region MoSi ₂ phase is not present 6.5 [mu] m, the maximum diameter of the MoSi ₂ phase 8.5 .mu.m, the average diameter of the MoSi ₂ phase was 7.1 [mu] m. Furthermore, the number density of silicide phases was 2 × 10 ⁴ mm ⁻² , and the relative density of the target was 99.9%. Moreover, when the elemental analysis of the target was conducted, the amount of impurities other than gas components was 1000 ppm or less in total, and good results were obtained.

  Next, the evaluation test regarding sputtering performance was done about the sputtering target of Example 1 mentioned above. Sputtering was performed by mounting the obtained sputtering target on the cathode of a sputtering apparatus and applying 1 kW of power to the target in an argon (Ar) atmosphere of 0.3 Pa. Sputtering is continuously performed for 3.5 kWh, and during that time, film formation is performed on the sample substrate at regular intervals for 20 seconds, and is observed in the Mo silicide thin film formed on the obtained sample substrate. The sputtering performance of the target was determined by evaluating the number of particles having a particle size of 0.25 to 3.0 μm.

  From this evaluation result, the value evaluated as the number of particles generated in a target life of 1.5 kWh or less as a standard value of the average number of particles that are constantly generated after the sputtering is stabilized after burn-in is 10 or less. It was confirmed that good performance was obtained throughout the target life.

(Example 2)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. Among these, the MoSi ₂ powder was pulverized to an average particle size of 4.5 μm using a jet mill. Both raw powders of Si powder and the pulverized MoSi ₂ are put into a stirring vessel of a vibration mill together with a molybdenum medium so that the atomic ratio is Mo / Si = 6.7, and the frequency is reduced by the vibration mill. Mixed for 1 hour at 800 cpm. Next, the obtained mixed raw material powder was classified with a # 200 sieve, filled in a graphite mold, and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

About the obtained sputtering target, it observed the structure | tissue image similarly to Example 1. FIG. FIG. 4 is an example of a tissue image observed by SEM observed in Example 2. In this structure image, although the MoSi ₂ phase which is considered to be a partly aggregated structure is observed, the entire structure shows a structure in which MoSi ₂ phase particles are finely dispersed. In Example 2, the maximum diameter of the circle that can exist in the region where no MoSi ₂ phase is present was 8.1 μm, the maximum diameter of the MoSi ₂ phase was 9.8 μm, and the average diameter of the MoSi ₂ phase was 8.2 μm. Further, the number density of the silicide phase is 1.5 × 10 ⁴ mm ⁻² , the relative density of the target is 99.9%, and the amount of impurities other than the gas components by the elemental analysis of the target is 100 ppm in total, and good results was gotten. And about the sputtering target of this Example 2, when the evaluation regarding sputtering performance was performed similarly to Example 1, the result was a particle number of 20 or less.

(Example 3)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. These two raw material powders were put into a stirring vessel of a medium stirring mill together with a medium made of zirconia so that Mo / Si = 6.7 in terms of atomic ratio and processed for 1 hour. The obtained mixed raw material powder was filled in a graphite mold and hot pressed in a vacuum atmosphere at a temperature of 1300 ° C. and a surface pressure of 300 kgf / cm ² to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

The obtained sputtering target was observed for the structure image in the same manner as in Example 1. In this example, a structure in which the finely crushed and pulverized MoSi ₂ phase was uniformly dispersed was observed. However, aggregated parts similar to those in Example 2 were also found. In Example 3, the maximum diameter of the circle that can exist in the region where no MoSi ₂ phase is present was 8.1 μm, the maximum diameter of the MoSi ₂ phase was 9.9 μm, and the average diameter of the MoSi ₂ phase was 8.0 μm. Further, the number density of the silicide phase is 1.5 × 10 ⁴ mm ⁻² , the relative density of the target is 99.9%, and the amount of impurities other than the gas components by the elemental analysis of the target is 1000 ppm or less in total, which is favorable. Results were obtained. And also about the sputtering target of this Example 3, when evaluation regarding sputtering performance was performed similarly to Example 1, the result was a particle number of 20 or less.

Example 4
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. These two raw material powders were put into a stirring vessel of a medium stirring mill together with a medium made of zirconia so that Mo / Si = 6.7 in terms of atomic ratio and processed for 10 hours. The obtained mixed raw material powder was filled in a graphite mold and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

When the obtained sputtering target was observed for a structure image in the same manner as in Example 1, a structure in which MoSi ₂ similar to Example 1 was dispersed finely and uniformly was observed in this Example. In Comparative Example 5, the maximum diameter of the circle that can exist in the region where no MoSi ₂ phase was present was 6.2 μm, the maximum diameter of the MoSi ₂ phase was 8.4 μm, and the average diameter of the MoSi ₂ phase was 7.0 μm. The number density of silicide phases was 2 × 10 ⁴ mm ⁻² , and the relative density of the target was 99.9%. However, as a result of the elemental analysis of the target, a relatively large amount of impurities such as Zr and Fe that are thought to be derived from the inner wall of the medium stirring mill or the medium components are observed, and the total of those impurities excluding gas components exceeds 3000 ppm. It was. And about the sputtering target of this comparative example 2, when evaluation about sputtering performance was performed similarly to Example 1, it was a result of 10 or less about the number of particles.

(Comparative Example 1)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. Next, these raw materials are heat-treated and deoxidized, and then both raw material powders obtained are placed in a stirring vessel of a vibration mill with a molybdenum medium so that the atomic ratio is Mo / Si = 6.7. And mixed with a vibration mill at a frequency of 800 cpm for 1 hour. The obtained mixed raw material powder was filled in a graphite mold and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

About the obtained sputtering target, it observed the structure | tissue image similarly to Example 1. FIG. FIG. 5 is an example of a tissue image observed by SEM observed in Comparative Example 1. In this structure image, the MoSi _two- phase particles in the Si matrix are generally coarse on average, and a large number of aggregates are formed and dispersed. Maximum diameter of the circle that can be present in a region MoSi ₂ phase is absent in the comparative example 1 is 10.5 [mu] m, the maximum diameter of the MoSi ₂ phase 19.7Myuemu, the average diameter of the MoSi ₂ phase was 18.7Myuemu. Further, the number density of the silicide phase was 1 × 10 ⁴ mm ⁻² , the relative density of the target was 99.9%, and the total amount of impurities other than gas components by elemental analysis of the target was 50 ppm or less. And when the sputtering target of this comparative example 1 was evaluated regarding sputtering performance like Example 1, the number of particles became 60 or more.

(Comparative Example 2)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, as MoSi ₂ raw material powder, purity 4N, was prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m. Among these, the MoSi ₂ raw material powder was put into a container of a medium agitating mill together with a ceramic medium, and pulverized by the medium agitating mill for 1 hour. Next, the obtained MoSi ₂ raw material powder and Si raw material powder were manually mixed for a sufficient time so that the atomic ratio was Mo / Si = 6.7. The obtained mixed raw material powder was filled in a graphite mold and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

About the obtained sputtering target, it observed the structure | tissue image similarly to Example 1. FIG. FIG. 6 is an example of a tissue image observed by SEM observed in Comparative Example 2. In this structure image, huge aggregates having a particle diameter of more than 100 μm formed by continuously aggregating innumerable primary particles of MoSi ₂ phase in the Si matrix are observed. Maximum diameter of the circle that can be present in a region MoSi ₂ phase is absent in the comparative example 2 is 15.7, the maximum diameter of the MoSi ₂ phase 120 [mu] m, the average diameter of the MoSi ₂ phase was 25 [mu] m. Further, the number density of the silicide phase was 1 × 10 ⁴ mm ⁻² , the relative density of the target was 99.9%, and the total amount of impurities other than gas components by elemental analysis of the target was 50 ppm or less. And when the sputtering target of this comparative example 2 was evaluated regarding sputtering performance like Example 1, the number of particles became 2500 or more.

(Comparative Example 3)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, MoSi as ₂ raw material powder, purity 4N, average particle size prepared MoSi ₂ powder 9 .mu.m, Mo / Si these as an atomic ratio = The mixture was mixed by hand for a sufficient time so that 6.7 was obtained. The obtained mixed raw material powder was filled in a graphite mold and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

About the obtained sputtering target, when the structure image was observed in the same manner as in Example 1, the size of MoSi ₂ present in the field of view was large in this example, and even very large aggregated particles could be confirmed, A pore-like portion that was not filled with ₂ MoSi grains was observed inside. Maximum diameter of the circle that can be present in a region MoSi ₂ phase is absent in the comparative example 3 20.1Myuemu, the maximum diameter of the MoSi ₂ phase 100 [mu] m, the average diameter of the MoSi ₂ phase was 25 [mu] m. Further, the number density of the silicide phase was 1 × 10 ³ mm ⁻² , the relative density of the target was 99.9%, and the total amount of impurities other than gas components by elemental analysis of the target was 50 ppm or less. And when the sputtering target of this comparative example 2 was evaluated regarding sputtering performance like Example 1, the number of particles became 300 or more.

(Comparative Example 4)
As Si raw material powder, purity 5N, prepared Si powder having an average particle size of 7 [mu] m, MoSi ₂ as the raw material powder, the purity 4N, prepared MoSi ₂ powder having an average particle diameter of 9 .mu.m, Mo / Si = 6 these atomic ratio The mixture was introduced into each inlet of the V-type mixer so as to be 0.7. The obtained mixed raw material powder was filled in a graphite mold and hot-pressed in a vacuum atmosphere to obtain a sintered body. The sintered body taken out from the mold was used as a disk-like sputtering target having a diameter of 164 mm and a thickness of 5 mm.

The obtained sputtering target was observed for a structure image in the same manner as in Example 1. In this example, a structure similar to that in Comparative Example 3 was observed. Maximum diameter of the circle that can be present in a region MoSi ₂ phase is not present in this Comparative Example 4 20.3Myuemu, the maximum diameter of the MoSi ₂ phase 80 [mu] m, the average diameter of the MoSi ₂ phase was 20 [mu] m. Further, the number density of the silicide phase was 1 × 10 ³ mm ⁻² , the relative density of the target was 99.9%, and the total amount of impurities other than gas components by elemental analysis of the target was 50 ppm or less. And when the sputtering target of this comparative example 2 was evaluated regarding sputtering performance like Example 1, the number of particles became 200 or more. )

These results are summarized in Table 1.

The present invention does not include coarse MoSi ₂ phase particles or aggregates in a structure in which MoSi ₂ phase particles are dispersed in the Si matrix, and has a structure in which MoSi ₂ phase particles are uniformly dispersed in the structure. A sputtering target capable of effectively suppressing the generation of particles during sputtering is provided. Such a sputtering target is suitable for a light-shielding layer of a photomask blank for circuit pattern exposure or a sputtering film of a phase shift layer at the time of manufacturing a semiconductor device with high definition and which does not allow mixing of particles.

Claims (10)

A sputtering target having a MoSi ₂ phase in a Si matrix, wherein the maximum diameter of a circle that can exist in a region where the MoSi ₂ phase does not exist is 9.0 μm or less, and the maximum diameter of the MoSi ₂ phase is 15 μm or less. And an average diameter of the MoSi ₂ phase is 13 μm or less. 2. The sputtering target according to claim 1, wherein the number density of the MoSi ₂ phase having a particle diameter of 0.35 μm or more is 1 × 10 ⁴ mm ⁻² or more in the sputtering surface of the sputtering target.   The sputtering target according to claim 1 or 2, wherein a relative density is 99% or more.   The total of Al, Cu, Fe, K, Na, Ni, W, and Zr is 2000 ppm or less, The sputtering target as described in any one of Claims 1-3 characterized by the above-mentioned.   The sputtering target according to any one of claims 1 to 4, wherein the sputtering target as a whole has a Si / Mo atomic ratio of 3.0 to 15.0.   It is used for manufacture of the light shielding film of a mask blank, or a phase shift film, The sputtering target as described in any one of Claims 1-5 characterized by the above-mentioned. It is a manufacturing method of the sputtering target as described in any one of Claims 1-6,
A step of preparing Si raw material powder having an average particle diameter of 1 to 50 μm;
Preparing MoSi ₂ raw material powder having an average particle size of 1 to 50 μm,
Crushing and mixing the Si powder and the MoSi ₂ powder in a multiple stirring blade rotating medium stirring mill;
A step of sintering the pulverized and mixed mixed raw material powder by hot pressing,
The manufacturing method of the sputtering target characterized by including.   The method for producing a sputtering target according to claim 7, wherein the step of pulverizing and mixing in the multiple stirring blade rotating medium stirring mill is performed at a rotational speed of 50 to 400 rpm for 0.5 to 10 hours. . It is a manufacturing method of the sputtering target as described in any one of Claims 1-6,
A step of preparing Si raw material powder having an average particle diameter of 1 to 50 μm;
Preparing MoSi ₂ raw material powder having an average particle size of 1 to 50 μm,
Crushing only the MoSi ₂ powder with a jet mill,
Crushing and mixing the pulverized MoSi ₂ powder and the Si powder in a vibration mill;
A step of sintering the pulverized and mixed mixed raw material powder by hot pressing,
The manufacturing method of the sputtering target characterized by including. The said sintering is implemented by the hot press of the temperature of 800-1400 degreeC, and the surface pressure of 150-400 kgf / cm < ² > in a vacuum atmosphere, The sputtering target as described in any one of Claims 7-9 characterized by the above-mentioned. Production method.