JPS61108132A - Manufacture of material containing metallic silicide radical - Google Patents

Abstract

PURPOSE:To reduce the oxygen content in target material by a method wherein a calcined body containing silicide forming metallic component and silicone component is impregnated with molten silicon. CONSTITUTION:A calcined body containing more than one kind of silicide forming metallic component and silicon component is produced. The calcination is performed by means of mixing and forming powder blended with specified composition ratio for heat treatment in nooxygen atmosphere. Next, the calcined body is brought into contact with molten Si meeting specified requirements to impregnate the calcined body with Si providing itself with two phases of metallic silicide and Si. In such a constitution, the oxygen content in calcined body becomes volatile carbon monoxide reacting to the molten Si to be discharged out of the system. Through these procedures, the oxygen content in a target material comprising the calcined body may be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for producing a target material used for forming a metal silicide film for semiconductor electrode wiring by sputtering.

[Conventional technology]

In recent years, MOSi2+WSi2. T
Refractory metal silicide films such as aSi2°TiSi2 have come into use. These high-melting-point metal silicides have lower specific resistance and higher corrosion resistance at high temperatures than conventional electrode wiring materials, so if these metal silicides are used for semiconductor electrode wiring, they can speed up calculations in semiconductor devices. It also has the advantage of being less susceptible to corrosion by chemicals and oxidation due to high-temperature processing during semiconductor manufacturing.

Generally, a sputtering method is used as a method for forming a high melting point metal silicide film. For example, when reacting MO and Si to form lMo5iz, which is a molybdenum silicide, the volume of the silicide after the reaction is smaller than the volume of both before the reaction, so the formed silicide film A large tensile stress occurs in the film, but if Si in the film is made excessive, the tensile stress can be kept low. Therefore, the composition of the film and therefore the composition of the target material is
(Atomic ratio)>2 is preferable. Furthermore, if the formed molybdenum silicide film has an excess of Si, the excess Si can be oxidized and a silica protective film can be formed on the molybdenum silicide surface, thus maintaining compatibility with conventional silicon gate processes. It also has the advantage of However, when the composition of the target material becomes Si/Mo (atomic ratio)>4, the composition of the film obtained by sputtering this target material also becomes St/Mo (atomic ratio)>4, resulting in a high film resistance. Undesirable. The above has been described using the case of MO as an example, but in general, the composition of the above-mentioned high melting point metal silicide film is 2<Si/M' (atomic ratio)≦
4 (however, M': high melting point metal), and in order to form a film with such a composition, M'S
Consisting of a composite structure of i2 and St, the composition is 2 <St/M'
It is essential to use a target material with an r atomic ratio)≦4.

Conventionally, a target material consisting of a composite structure of M'S 12 and Si and having a composition of 2 < St /M' (atomic ratio) < 4 has been manufactured as follows. That is, raw material powders (M/powder and Si powder) are mixed so as to have a predetermined target composition and sintered. As the sintering method, a normal pressure sintering method, a hot press method, etc. are used.

[Problem that the invention seeks to solve]

In manufacturing using such a powder metallurgical method, a large amount of oxygen (oxygen content: approximately 13,000 ppm) is contained in the raw material powder, especially Si powder, so a large amount of oxygen is incorporated into the manufactured target ( Acid cumulative content: about 250
0 ppm), as a result, there is a drawback that a large amount of oxygen exists in the film formed by sputtering, which increases the resistance when the film is used for electrode wiring of a semiconductor.

Since oxygen in the Si powder is contained in the form of SiO□, it cannot be removed by normal methods.

The purpose of this invention is to obtain a desired composition, e.g. 2<Si/M
(atomic ratio)≦4 (where M is a silicide-forming metal component of at least 1 m).
2) It is an object of the present invention to provide a new method for producing a target material having a composite structure consisting of two phases of 2) and Si and having a reduced oxygen content.

[Means for solving problems]

As a result of various studies, the present inventors have found that by impregnating a pre-sintered body composed of at least one silicide-forming metal component and a silicon component with molten silicon, the pre-sintered body contains mainly SiO2.
Oxygen contained in the form of
It reacts with molten Si generated by melting through contact with i or indirect heating, becomes volatile silicon monoxide, and is released outside the system, making it possible to obtain a target material with extremely reduced oxygen content. I found out.

This invention was invented based on the above findings, and includes: (1) impregnating a pre-sintered body containing at least one silicide-forming metal component and a silicon component with molten silicon to form a metal silicide; A method for producing a target material with a reduced oxygen content for forming a metal silicide film for semiconductor electrode wiring, characterized by producing a sintered body containing silicon and with a reduced oxygen content.

(21) For forming a metal silicide film for semiconductor electrode wiring according to claim 1, in which all or part of the silicide-forming metal component and the silicon component form a compound consisting of both elements. This is a method for producing target material with reduced oxygen content.

The manufacturing method of this invention will be described below.

(1) About the pre-sintered body The pre-sintered body consists of at least one silicide-forming metal component and a silicon component. Here, the silicide-forming metal component is
Mo, W, Ta, Ti, V, Cr+Zr, Nb.

It is a metal component such as Hf, Re, Y, etc. that can form a metal silicide film with low specific resistance. These silicide-forming metal components may be used alone or in combination of two or more. All or part of the silicide-forming metal component and the silicon component in the pre-sintered body form a compound consisting of both elements. That is, if all of the silicon components 61 form a compound, the pre-sintered body is
2, or other compounds of M and 3i (e.g. M05
In the case where a part of the silicon component forms a compound, the pre-sintered body consists of MgI2 and Si1 or another compound of M and St and Si. When two or more types of silicide-forming metal components are used together, the two or more types of silicide-forming metal components and silicon components are the silicide of one metal and the silicide of another metal in the pre-sintered body. In some cases, the structure may be a mixture of metal components and Si in some cases, or in other cases, it may be a structure consisting of a composite metal silicide containing two or more metal components as a solid solution and in some cases Si. ,
Alternatively, the composite metal silicide may be partially formed with a silicide of a certain metal and a silicide of another metal, or may be composed of the composite metal silicide blended as a starting material, and optionally Si. Furthermore, in addition to at least one silicide-forming metal component and a silicon component, the pre-sintered body contains other trace components, such as R.
It may contain components such as u, pd, and Pt.

In addition, impurities that can be included without causing any problems include Mn,
Examples include Fe, Co, Ni, and Mt.

The temporary sintered body is manufactured, for example, as follows. That is, powders of MSi2+ M, Si, or other compounds of M and Si are used as raw materials, or two or more types of MS 12 powders are used, or M powders and Si powders are used.

When using powders of other compounds of M and Si, after thoroughly mixing two or more of these at the required composition ratio,
(dry) and mold using a -axial press or isostatic press.
Heat treatment is performed at a temperature within the range of 0 to 1750° C. for an appropriate time determined by the temperature to obtain a temporary sintered body having the structure as described above.

The pre-sintered body can also be directly produced in one step from a mixed powder by a vacuum hot press method, without performing the two-step molding and heat treatment as described above.

Furthermore, as the pre-sintered body, it is also possible to use a pre-sintered body formed during heating of a compact formed using a -axis press, a hydrostatic press, etc. for impregnation in this step. (Example 8).

This heat treatment (preliminary sintering) maintains the shape so that it can withstand contact with molten Si in the next step, and by changing the heat treatment (preliminary sintering) temperature, etc., the density of the preliminarily sintered body can be changed. can be adjusted. When M and Si are used as raw materials, this heat treatment (preliminary sintering)
In the process, a reaction occurs between M and Si, resulting in MgI2
Alternatively, other compounds of M and Si are generated. Furthermore, when two or more types of M and/or two or more types of M and Si compounds are used as raw materials, a solid solution also occurs.

(II) For the impregnation step, the pre-sintered body is placed in a vacuum (preferably ~10-3 torr)
The pre-sintered body is impregnated with Si by bringing it into contact with molten Si (C ~ 1 ppm) with a low oxygen content, preferably at a temperature of 1430°C to 1500°C. It is possible to obtain a target material which is made of a sintered body having a composite structure made of two phases of St and whose oxygen content is extremely reduced.

This is because through this impregnation step, the oxygen content in the temporary sintered body reacts with the molten St and becomes silicon monoxide, which is volatilized and removed, as described in the findings section. The accumulated acid content of the target material made of a sintered body can be reduced to the same level as the oxygen content in the molten Si used for impregnation by making the time in contact with molten Si sufficiently long. Therefore, the time is preferably 60 to 120 minutes.

In addition, C~1 ppm') fused Si with low oxygen content
For this purpose, ultra-high purity St for semiconductors may be used.

This impregnation step also causes sintering, and when a pre-sintered body made of another compound of M and Si is used, the formation of MgI2 also occurs. In addition, in the case of a pre-sintered body obtained by a two-step process of forming and heat treatment, the voids in the pre-sintered body are filled with Si by impregnation with molten St, so that the target material made of the obtained sintered body is 817M (atomic ratio) increases, but if the temporary sintered body is obtained in one step by the vacuum hot press method and its relative density is 9896 or more, the molten Si and the temporary sintered body will be mixed in the impregnation process. S of
The Si 7M (atomic ratio) of the target material obtained increases because the Si in the temporary sintered body that is lost due to replacement with i or combination with oxygen, which is an impurity in the temporary sintered body, is only replenished. do not.

Eventually, the impregnation process results in metal silicides (e.g. Msi2
) and Si, and a sintered body with extremely reduced oxygen content can be obtained.

Regarding the adjustment of the Si/MC atomic ratio of the target material (iill), the above atomic ratio is based on the St
It is possible to change the atomic ratio to a desired one by changing the atomic ratio of /M or by changing the density of the pre-sintered body.

For example, when the temporary sintered body is a Mo5iz temporary sintered body manufactured by a two-step process of forming and heat treatment, the Si/Mo ratio in the raw material mixture consisting of Mo powder and Si powder is 315, that is, the MO excess. At this time, the amount of MoSi2 generated during impregnation with molten Si is too large and the shape cannot be maintained due to the large amount of reaction heat generated. According to the experimental results, S in the raw material mixture
When the i/Mo ratio is approximately 2.0, the composition of the sintered body is Si
/MO ratio-E of 4.0 was obtained. Therefore, when producing a pre-sintered body through a two-step process of forming and heat treatment, it is appropriate to vary the Si/Mo ratio in the raw material mixture within the range of 315 to about 2.0. By this,
On the other hand, Mo5iz temporary sintering is performed from, for example, Mo powder and Si powder in one step by a vacuum hot press method, in which a sintered body having a Si/Mo ratio of -2.57 to 4.0 is obtained. When producing a body, if the S 1 /Mo ratio in the raw material mixture for the temporary sintered body is >2 and the hot press temperature is 1400°C or higher, the relative density of the temporary sintered body will easily change. is 9896 or more, and in such a pre-sintered body, when impregnated with molten Si, the Si contained in the pre-sintered body is
Si in the raw material mixture for the temporary sintered body is only replenished by replacement of Si in the temporary sintered body, which was lost due to replacement with oxygen and combination with oxygen, which is an impurity in the temporary sintered body. The Mo ratio and the ratio g in the target material are about the same value. From the viewpoint of ease of adjusting the Si/Mo ratio in the target material, in the vacuum hot press method, it is preferable that the Si/Mo ratio in the raw material mixture for the pre-sintered body is 2 (see @Table 4). )
. If the Si/Mo ratio of the raw material mixture for the pre-sintered body produced by the vacuum hot pressing method is <T, the shape cannot be maintained during impregnation as in the above-mentioned two-stage process. Also in the vacuum hot press method, ÷≦Si/MO is found in the raw material mixture.
In the case of ≦2, it depends on the density of the temporary sintered body, and the composition of the sintered body has a Si/Mo ratio of -2, 10 to 4. An OOO product is obtained (see Example 5).

Next, a description will be given of how the density of the pre-sintered body is changed and how the Si7M ratio of the target material is changed accordingly.

First, the density of the pre-sintered body can be changed by changing the heat treatment (pre-sintering) temperature. This is particularly noticeable when a pre-sintered body is produced in a two-step process of forming and heat treatment; however, as the heat treatment temperature increases, the density of the obtained pre-sintered body also increases. The higher the value, the higher the melting S
Since the impregnation amount of i decreases, S of the target material obtained
The i7M ratio decreases (see Table 2 for a comparison of Examples 1 and 3).

Further, even when a pre-sintered body is produced by a vacuum hot press method, the density of the pre-sintered body can be easily controlled by changing the hot press temperature or press pressure. This means that the Si7M ratio in the raw material mixture for the pre-sintered body is equal to ≦Si.
This is particularly noticeable when /M≦2. In this case as well, as in the case of the two-stage heat treatment step, as the density of the pre-sintered body increases, the amount of molten Si impregnated decreases, so the Si7M ratio of the obtained target material decreases.

Even if the heat treatment temperature is the same and the Si7M ratio in the raw material mixture is the same, the density of the obtained pre-sintered body will differ depending on whether a compound or a single substance is used as the raw material. For example, if a raw material mixture consisting of Mo powder and Si powder with a Si/Mo ratio of -2 is molded and then heat-treated at 1500°C, a pre-sintered MoSi2 body with a density of 3.00 t/cm" can be obtained. , when MoSi2 powder is used as the raw material and molded and heat treated in the same manner as above, 4.70 t
/ cm". In other words, when a compound is used, a pre-sintered body with a higher density can be obtained than when a single substance is used, so the amount of molten Si impregnated can also be reduced. The sintered body obtained also has a small si/M ratio.

As mentioned above, the target material Si 7M (atomic ratio)
is adjusted to a desired value, for example, a value greater than 2 and 4 or less, by changing the atomic ratio of St/M in the raw material mixture for the pre-sintered body or by changing the density of the pre-sintered body. can do.

〔Example〕

Hereinafter, the configuration and effects of the present invention will be explained in detail using Examples.

Example 1 MO powder with an average particle size of 3 μm (oxygen content 1400 ppm)
) and Si powder with an average particle size of 1.5 μm (oxygen content 1300
0ppm), 63 parts by weight of MO powder and 3 parts by weight of Si powder.
After mixing a composition consisting of 7 parts by weight in a ball mill using hexane as a mixed solvent for 2 hours, it was thoroughly dried, and then heated to 30 tin 730 m using a -shaft press C press pressure: 2 t/d).
A molded body with a size of m x 5 mm is produced. This molded body was heated at a temperature of 1200°C for 1 hour in a vacuum of 10-3 torr to make Mn5iz, and then heat treated at 1700°C for 1 hour to obtain a pre-sintered body (with a density of 4.10 f/cm).
An oxygen content of 1800'ppm) is obtained.

10 to the MO8i2 pre-sintered body thus obtained
At 1500℃ in a vacuum of rr, the oxygen content is l.
ppm of molten Si was impregnated for 4 hours and then cooled in the furnace.The composition was Si/MO ratio = 3.06 and MoSi2 and Si
Sintered body consisting of a composite structure (oxygen content 6 ppm)
was manufactured.

By changing the impregnation time in the above manufacturing method, Mo5i
Similar molten Si impregnation treatment was performed using a WS 12 , TaSi 2 or TiSi 2 pre-sintered body instead of the Z pre-sintered body. Note that the heat treatment temperature and silicon impregnation temperature in the case of TiSi2 are both 1430°C. These results are shown in Table 1 together with the above results.

Example 2 MO8j2 powder C acid cumulative content with average particle size of 5 μm: 5500
ppm) with a press pressure of 2t/cf using the -axial press method.
Press molded at A, 30 tmn x 30 ttrm
It was made into a rectangular parallelepiped with a size of 5 mm. The density of a rectangular parallelepiped is 3,3
At 7 cm3, the density ratio is 52.9%. This rectangular parallelepiped was heat-treated at 1450° C. for 1 hour in a vacuum of 10 −3 torr to obtain a pre-sintered body (oxygen content: 3500 ppm) with a density of 4.80 f/am 3 .

Table 1 [Table 1] Next, the sample was brought into contact with molten St (oxygen content: 1 ppm) for 90 minutes at a temperature of 1450° C. in a vacuum of 0 torr to impregnate Si, and then cooled in a furnace.

The produced sintered body has a density of 5.33 f/am” and a porosity of 19I5 or less.
The content of i2 is 77% by volume, the remainder being Si, and the composition is St/MO (atomic ratio) -2.60. And the oxygen content was 10 ppm.

The results obtained when the preliminary sintering temperature was varied in the same manner are shown in Table 2 together with the above results. In addition, the preliminary sintering temperature is 150
If the temperature is 0°C or higher, the temperature for impregnating Si should be set to 1500°C.
℃.

Table 2 Example 3 Using the same raw materials, blending composition (Si/Mo diatomic ratio is 2.006), matching method, and molding method as in Example 1,
Produce molded bodies of the same size. The density of this compact is 2
．． 52 f/cmF. 10""" of this molded body
The temperature was raised at a rate of 600°C/hr to 1200°C in a vacuum of torr, and the temperature was increased to 1500°C.
C. for 1 hour to obtain a pre-sintered body (oxygen content: 2600 ppm) with a density of 3-00 f 7 cm''.

This pre-sintered body was heated at a temperature of 1500°C in a vacuum of 10 torr for 60 minutes to melt Si (oxygen content = 1 ppm).
) and impregnated with Si, and then cooled in a furnace. The density of the manufactured sintered body is 4.28? /cm3, and the porosity is 196 or less, and the MoSi2 content in the sintered body is 50% by volume, the remainder being Si, and the composition is Si/cm3.
MO (atomic ratio) was −4,00. The oxygen content of the sintered body was 7 ppm.

The results of repeating the above method by changing the mixing ratio of the raw materials MO powder and Si powder are shown in Table 3 together with the above results.

Example 4 Similar to Example 3, Si/Mo (atomic ratio) = 2.2
8, and the raw material mixture consisting of MO powder and Si powder is 1
Temperature of 300℃, pressure of 150Kgf/m, degree of vacuum 10
- Preliminary sintered body C with a density of 5.50?/cm after hot pressing for 1 hour under the condition of "t'orr" Oxygen content:
6200 ppm).

Table 3 This pre-sintered body was impregnated with 81 under the same conditions as in Example 3 to produce a sintered body.

The density of this sintered body is 5.77 f/cm'', the composition is St/MO (atomic ratio) -2.30, the content of MoSi2 in the sintered body is 87% by volume, and the remainder is 81%. there were.

The oxygen content was 19 ppm.

Table 4 shows the results when the same method as above was carried out by changing the mixing ratio of MO and St in the raw material mixture, together with the above results.

Table 4 Example 5 MoSi2 powder with an average particle size of 5 μm (oxygen content: 5500
ppm) at a temperature of 1230℃, 150Kgf/Qm
Mo5 with a density of 4.68 g/CrIL3 was hot pressed for 1 hour under the conditions of a pressure of 2 and a vacuum of 10'-'' torr.
An iz temporary sintered body (oxygen content: 5100 ppm) was obtained.

This pre-sintered body was impregnated with Si under the same conditions as in Example 3 to produce a sintered body.

The density of this sintered body is 5.2697cm'', and the composition is Si.
/Mo (atomic ratio) -2,67, and MoS in the sintered body
The i2 content was 75% by volume, with the remainder being Si.

The oxygen content of this sintered body was 13 ppm.

Table 5 shows the results when the same method as above was carried out by changing the mixing ratio of MO and Si in the raw material mixture, or by changing the hot press temperature and hot press pressure, along with the above results. .

Table 5 = 22- Example 6 wsi2 powder with an average particle size of 4 μm (oxygen content: 6200
pl)m) with a press pressure of 2t/c using a -shaft press.
Press molded with rA, 30 mm M 30 MmX
It was made into a rectangular parallelepiped with a size of 5 mx+. The density of a rectangular parallelepiped is 4
．． This rectangular parallelepiped was heat-treated at a temperature of 1500° C. in a vacuum of 10 torr for 1 hour to form a pre-sintered body with a density of 7,409/cm” (oxygen content: 3
800 ppm) was obtained. This temporary sintered body was heated to a temperature of 15o.
After contacting and impregnating with molten Si (oxygen content = 1 ppm) for 60 minutes at 0°C and vacuum level of 10-3 torr, a sintered body with a density of 7.98 f/am was obtained using a furnace-cooled sheet. The W St 2 content in this sintered body was 75% by volume, the rest was Si, and the composition was St/W (atomic ratio) = 2
．． It is 67.

The oxygen content was 12 ppm.

A sintered body made of TaSi2 and St was produced in exactly the same manner as described above, except that Ta5i2 powder (oxygen content: 58001) I)m ) having an average particle size of 4 μm was used as the TaSi2 powder. The density of the obtained sintered body is 7.1
69/am”, the content of 'l'aSi2 in the sintered body is 71%, and the composition is Si/Ta (atomic ratio) = 2.8.
8 and the oxygen content was 10 ppm.

In the case of M-Ti, TiSi2 powder with an average particle size of 45 μm (
A sintered body with a density of 390 g/cm" was manufactured by impregnating Si at a low Si impregnation temperature of 1430° C. (oxygen content: 2500 ppm). I S x 2 content is 86% by volume and the rest is Si
The composition is Si/Ta (atomic ratio) = 2.34. And the oxygen content was 9 ppm.

Example 7 MO powder with an average particle size of 3 μm (oxygen content: 1400 pp
m ), Si powder with a diameter of 1.5 μm (same: 13000 p
11m), 5μm 1)4oSi2 powder (same: 5
500ppm), 4μm W S l 2 powder (6200ppm), 4pm TaSi2 powder (same:
5800 ppm) and 45 μm TIS
12 powder (same: 2500 ppm) was prepared,
The compositions are blended according to the composition shown in the table, and a molded article of the same size is produced by the same mixing and molding method as in Example 1. Next, in 42 and 5, the temperature was 1200°C, 1
It is heated in a vacuum of 0-3 torr for 1 hour, and then heat-treated at 1700° C. for 1 hour to obtain a temporary sintered body. Also, at 41.3° 4 and 6, the temperature of 1500°C,
Heat treated in a vacuum of 10-3 torr for 1 hour,
The pre-sintered body has the e-collection amount shown in Table 6.

Next, in the pre-sintered bodies of 41.2 and 5, 10-3
torr vacuum at 1500°C for 1 hour, and in the pre-sintered bodies of 3s 4 and 6, 1
Impregnation with molten Sl having an oxygen content of 1 ppm at 1430° C. for 1 hour in a vacuum of 0 torr,
Sintered bodies having the MSi2 content, Si7M atomic ratio, and oxygen content shown in Table 6 were obtained.

Example 8 MoSi2 powder with an average particle size of 5 μm (oxygen content: 5500
ppm) with a press pressure of 2t /
Press molded with ctli, 30mm”i 30tprm
It was made into a rectangular parallelepiped with a size of 5 m. The density of a rectangular parallelepiped is 3.309/
cm'' and the density ratio is 52.996.

3.72 plate-like Sts are stacked on this rectangular parallelepiped, and 135
By raising the temperature to 0°C at a heating rate of 300°C/hr, a temporary sintered body is generated, and further heating to 1425°C at a heating rate of 50°C/hr. 3to
After being kept in a vacuum of rr for 30 minutes, it was cooled in a furnace. Plate Si
is melted and impregnated into MoSi2 pre-sintered body to have a density of 5.
．． A sintered body having a porosity of 18 f//cm'' and a porosity of 196 or less was obtained.

The content of MOSi2 in this sintered body is 73% by volume, the remainder is Si, and the composition is St/Δl[0 (atomic ratio) -2,7
It is 5. And the oxygen content was 10 ppm.

Similarly, WSi2 powder (oxygen content: 6200 ppm) with an average particle size of 4 μm and Ta512 powder C with an average particle size of 4 pm were prepared.
Oxygen content: 5800 ppm), 45 pm T
-i S i 2 powder (oxygen content: 2500 ppm
Table 7 shows the results of carrying out the above method using

[Overall Effects of the Invention] By the production method of the present invention, it is possible to produce a target material whose oxygen content is significantly reduced to 20 ppm or less. If used, it is possible to form a high melting point metal silicide film with an oxygen content comparable to that of the target material. As mentioned above, this film has an extremely low amount of acid collection, and thus has a low film resistance, and is therefore suitable for use in semiconductor electrode wiring.

Claims (2)

[Claims] (1) A pre-sintered body containing at least one silicide-forming metal component and a silicon component is impregnated with molten silicon to produce a sintered body containing a metal silicide and silicon with a reduced oxygen content. 1. A method for producing a target material with reduced oxygen content for forming a metal silicide film for semiconductor electrode wiring. (2) For forming a metal silicide film for semiconductor electrode wiring according to claim 1, in which all or part of the silicide-forming metal component and the silicon component form a compound consisting of both elements. A method for producing target materials with reduced oxygen content.