JPH0610124A - Refractory metal silicide target and manufacturing method thereof - Google Patents

Abstract

(57) [Summary] [Structure] MSi ₂ (where M is Mo, W, Ta, Z
In a refractory metal silicide target composed of a sintered body of refractory metal silicide particles represented by (1 kind selected from r, Ti, Nb, Cr) and Si particles, the refractory metal silicide particles Average particle size 0.5 to 10 μm
And the average grain size of the Si grains is 0.1 to 20 μm.
It is a refractory metal silicide target characterized by [Effect] Since the target structure has a structure in which the refractory metal silicide grains are uniformly dispersed, it is possible to form a thin film with excellent characteristics and reduce the generation of particles. It is possible to dramatically improve the product yield in such cases.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractory metal silicide target and a manufacturing method thereof, and more particularly to a refractory metal silicide target in which particles generated during sputtering are suppressed and a manufacturing method thereof.
The refractory metal in the present invention includes Mo, W, Ta,
Zr, Ti, Nb, Cr and the like.

[0002]

2. Description of the Related Art Conventionally, polysilicon has been used as an electrode or wiring material for semiconductor devices. However, as semiconductor devices become highly integrated, the signal propagation delay due to the resistance of the polysilicon electrode becomes a problem, and in order to facilitate the formation of MOS devices by the self-alignment method, the melting point of polysilicon is higher than that of polysilicon for the gate electrode, source electrode and drain electrode. The use of high quality materials is desired. Under these circumstances, as a high melting point metal material having a lower resistivity than polysilicon, a high melting point metal silicide electrode having excellent compatibility with the silicon gate process has been studied, and molybdenum silicide (MoSi ₂ ) has been proposed as a promising high melting point metal silicide. , Tungsten silicide (WSi ₂ ) and other materials are attracting attention.

By the way, as a method effective for forming a refractory metal silicide thin film for an electrode or wiring of a semiconductor device, a sputtering method, an electron beam evaporation method and the like have been conventionally known. The sputtering method is a method in which argon ions are made to collide with a target plate to release a metal, and the released metal is deposited on a substrate facing the target plate.The electron beam vapor deposition method heats an evaporation source by an electron beam to perform vapor deposition. Is the way to do. The purity and other properties of the film produced by this sputtering method or vapor deposition method depend on the purity, composition, sputtering characteristics, etc. of the target plate. Hereinafter, in the present specification, the “target” includes all refractory metal silicide articles formed into a plate shape or other forms as a sputtering source or a vapor deposition source.

As a general method of manufacturing this target, Si powder is mixed with refractory metal powder such as Mo or W, or silicide powder having a different composition is mixed and sintered by hot pressing to form a plate or the like. It is shaped and manufactured. As a method for synthesizing a refractory metal silicide, a synthesizing method disclosed in JP-A-62-123010 is known. This method is a method for synthesizing Mo or W disilicide by adding Si powder to Mo powder or W powder in excess of a target molar value and mixing, and synthesizing the mixed powder at 3 kg or more under high temperature vacuum. Is.

[0005]

However, according to the above-mentioned conventional method, it is difficult to control the particle size distribution of the refractory metal silicide particles and the free Si particles in the synthesized refractory metal silicide target, and it is difficult to control the particle size distribution in the manufactured target. There was a problem that the particle size distribution of the silicide particles and the free Si particles was extremely large, and the dispersion of these components in the target became uneven. FIG. 1 and FIG. 2 exemplify the particle size distribution of disilicide and free Si in a refractory metal silicide target produced by a conventional method. As shown in these figures, disilicide ( There are two or more peaks in the particle size of high melting point metal silicide) and the particle size of free Si.
It shows that there is a large variation in the particle size distribution. More specifically, the average particle diameter of the refractory metal silicide is 17 μm,
The average particle size of free Si is 48 μm, and the variation with respect to the average particle size is −60 to + 110% in the case of silicide, and the free S
i was about -70 to + 220%.

When such a conventional target is used to form a film on a wafer by a sputtering method, the average grain size of each of the refractory metal silicide grains and the free Si grains in the target structure is large, and the target grains have a large average grain size. Due to the large variation in particle size, the number of particles of 0.3 μm or more generated on the wafer is 300 to 1 for a 6-inch wafer.
As many as 000 were generated, the characteristics of the thin film were deteriorated, and the yield of semiconductor products was poor.

The present invention has been made in view of the above circumstances. It is possible to form a thin film having excellent characteristics, suppress the generation of particles during sputtering, and dramatically improve the product yield of semiconductor products and the like. The purpose is to provide a possible refractory metal silicide target.

[0008]

A refractory metal silicide target according to the present invention has the general formula MSi ₂ (where M
Is a refractory metal silicide grain represented by Mo, W, Ta, Zr, Ti, Nb, and Cr), and a refractory metal silicide target composed of a sintered body containing Si grains. The high-melting-point metal silicide grains have an average grain size of 0.5 to 10 μm, and the Si grains have an average grain size of 0.1 to 20 μm.

Furthermore, in the refractory metal silicide target, the grain size distribution of the refractory metal silicide grains is 95% or more within ± 40% of the average grain size, and the Si is
It is desirable that the particle size distribution of the particles is such that 70% or more falls within ± 50% of the average particle size.

The method of manufacturing a refractory metal silicide target according to the present invention uses the general formula MSi ₂ (where M is one kind selected from Mo, W, Ta, Zr, Ti, Nb and Cr). The average particle size is 0.5 to 10
High melting point metal silicide with μm and average grain size of 0.1
A powder containing Si having a particle size of ˜20 μm at a heating temperature of 140
Sintering is performed under the conditions of 0 to 1415 ° C., pressure of 100 to 200 kg / cm ² , and sintering time of 1 to 5 hours.

[0011]

Function The refractory metal silicide target of the present invention is
The refractory metal silicide grains in the target structure have an average grain size of 0.5 to 10 μm, and the Si grains have an average grain size of 0.1.
By setting the thickness to ˜20 μm, the dispersion of each component in the target structure is made uniform, and when this target is used as a sputter target, the particle generation rate decreases.

[0012]

EXAMPLE A refractory metal silicide target according to the present invention has a general formula MSi ₂ (where M is Mo, W, Ta,
The high melting point metal silicide (hereinafter referred to as MSi ₂ ) particles represented by Zr, Ti, Nb, and Cr), and a sintered body containing Si particles are used. ₂ particles have an average particle size of 0.5 to 10 μm, Si
The average particle size of the particles is in the range of 0.1 to 20 μm. In addition, the particle size distribution of the MSi ₂ particles is 95% or more within ± 40% of the average particle size, and the particle size distribution of the Si particles is 70% or more within ± 50% of the average particle size. Is desirable.

If the average particle size of MSi ₂ particles and Si particles is smaller than the above range, the oxygen content in these particles increases, and the characteristics of the thin film formed by the sputtering method deteriorate. On the other hand, MSi ₂ grains and Si
If the average particle size of the particles is larger than the above range, the sintered density of the target is reduced, and thus the number of particles generated during sputtering increases. Further, if the particle size distribution of MSi ₂ grains and Si grains is larger than the above range, the distribution of each component in the target structure becomes non-uniform and the characteristics of the thin film deteriorate.

In the manufacturing method according to the present invention, when the above target is manufactured, M having an average particle size of 0.5 to 10 μm is used.
A powder containing Si ₂ particles and Si particles having an average particle size of 0.1 to 20 μm was heated at a temperature of 1400 to 1415 ° C. and a pressure of 100 to
A target having a desired shape is manufactured by hot pressing under the conditions of 200 kg / cm ² and a sintering time of 1 to 5 hours.

The powder containing MSi ₂ and Si particles is Mo,
W, Ta, Zr, Ti, Nb, and one or refractory metal powder and Si powder selected from among Cr by heating the reaction to produce a MSi _2, unreacted this MSi ₂ Si (free Si It is produced by crushing a fired product containing a).
The high melting point metal powder and Si powder used here must be high purity materials of 4N or more. The average particle size of these raw material powders is preferably about 0.3 to 8 μm for high melting point metal powder such as tungsten (W) and about 0.2 to 15 μm for Si. After thoroughly mixing these raw material powders in a mixer, 1250 to 1250 in a reduced pressure atmosphere of 5 × 10 ⁻³ Torr or less.
It is made to react by firing at 1350 ° C. for 30 minutes to 4 hours. The calcined product containing MSi ₂ and unreacted Si (free Si) obtained by this calcining is crushed using a crusher such as a ball mill,
The powder has a particle size of 250 μm or less. Of the fired powder structure, the generated MSi ₂ particles expand 10 to 30% more than the refractory metal powder before the reaction, and the average particle size is 0.5 to 10 μm.
m. On the other hand, the unreacted Si particles are partially crushed and partially agglomerated, so that the average particle diameter becomes about 0.1 to 20 μm.
The crushing after firing does not need to be excessively crushed.

Then, the calcined powder is heated to a heating temperature of 1400.
Hot pressing is performed under the conditions of ˜1415 ° C., pressure of 100 to 200 kg / cm ² , and sintering time of 1 to 5 hours. In this sintering by hot pressing, since Si is plastically deformed by heating it to a temperature just below the melting point of Si, Si is converted into MSi.
Fills the space between _two grains to increase the sintering strength. The pressure applied by this hot press may be such that Si is plastically deformed.
~ 200 kg / cm ² , preferably 130-180 kg
/ Cm ² is suitable. The heating time required for sintering is preferably about 1 to 3 hours.

(Experimental Example) 7 kg of tungsten powder having an average particle size of 1.7 μm (purity 5N) and 3.1 kg of Si powder having an average particle size of 4.5 μm (purity 6N) were used for 30 minutes using a V-type mixer. Mixed. This mixed powder was fired at 1280 ° C. for 2 hours in a reduced pressure atmosphere of 2 × 10 ⁻³ Torr or less, and after this firing, the product was crushed by a ball mill for 1 hour. The obtained powder was sieved with a 60 mesh to obtain a powder of 250 μm or less. Then, the powder obtained was subjected to a pressure of 140 kg / cm ² and a temperature of 141 in a reduced pressure atmosphere of 5 × 10 ⁻⁴ Torr or less.
Hot pressing was performed at 0 ° C. for 2 hours. The obtained hot-pressed sintered body was appropriately ground to prepare a sputtering target. This target was bonded to a target support using Pb-40% Sn solder and mounted on a sputtering device. Using this target (target of the present invention), 6
Using an inch wafer as a substrate, DC magnetron sputtering was performed at an output of 2 kW in an atmosphere of Ar at 5 × 10 ⁻³ Torr.

On the other hand, a tungsten silicide target was prepared by the conventional method. In this conventional product target, the average particle size of refractory metal silicide is 17 μm, the average particle size of free Si is 48 μm, and the variation with respect to the average particle size is −60 to + 110% in the case of disilicide and −7 for free Si.
It was about 0 to + 220%. This conventional target was also sputtered on the wafer under the same conditions as the target of the present invention described above.

A thin film was formed by a sputtering method using both of these targets, and the number of generated particles having a size of 0.3 μm or more was measured. As a result, when the conventional target was used, 300 to 1000 particles were generated. While a large number of particles were generated, the number of particles generated by the target of the present invention was as small as about 10 to 30.

Further, as a result of examining the structures of both targets by an electron microscope, the target of the present invention was found to have WSi ₂ grains (white portion in the figure) and free Si grains (black portion in the figure) as shown in FIG. As shown in FIG. 4, the conventional target has a large variation in the sizes of WSi ₂ particles and free Si particles, and in particular, free Si is a large particle, while the particles are almost uniformly dispersed. .

[0021]

As described above, according to the present invention,
Refractory metal silicide grains and free Si in the target structure
Since the average particle size and particle size distribution of the particles are almost uniform, and both particles have a structure in which they are uniformly dispersed, when this target is used as a sputtering target, a thin film with excellent characteristics can be formed. Since it is possible to reduce the generation of particles, there is an excellent effect that the product yield in semiconductor products and the like can be dramatically improved.

[Brief description of drawings]

FIG. 1 is a graph illustrating a particle size distribution of disilicide in a conventional refractory metal silicide target.

FIG. 2 is a graph illustrating a particle size distribution of free Si in a conventional refractory metal silicide target.

FIG. 3 is an enlarged view showing a structure of a target of the present invention produced in an experimental example of the present invention.

FIG. 4 is an enlarged view showing a structure of a conventional target manufactured in an experimental example of the present invention.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H01L 21/285 301 T 9055-4M

Claims (3)

[Claims] 1. The general formula MSi ₂ (where M is Mo,
In a refractory metal silicide target composed of a sintered body of refractory metal silicide particles represented by W), Ta, Zr, Ti, Nb, and Cr) and a Si particle, The average grain size of the metal silicide grains is 0.
5 to 10 μm, and the average grain size of the Si grains is 0.1.
A refractory metal silicide target having a thickness of 1 to 20 μm. 2. The particle size distribution of the refractory metal silicide particles is 95% or more within ± 40% of the average particle size, and the particle size distribution of the Si particles is 70% within ± 50% of the average particle size.
The refractory metal silicide target according to claim 1, wherein the above is included. 3. The general formula MSi ₂ (where M is Mo,
W, Ta, Zr, Ti, Nb, Cr, which is one kind selected from the group) and has an average grain size of 0.5 to 10 μm, and a high melting point metal silicide having an average grain size of 0.1 to 0.1 μm. 20
A powder containing Si having a thickness of 1 μm is heated at a heating temperature of 1400 to 1
A method for producing a refractory metal silicide target, which comprises sintering at 415 ° C., a pressure of 100 to 200 kg / cm ² , and a sintering time of 1 to 5 hours.