TW201313930A - MoTi target and method for producing the same - Google Patents

Abstract

A MoTi target and method for producing the same are provided in the invention, which can improve membrane peeling problem and further maintain a low resistance value. The invention provides the MoTi target which has a composition including 20 atom% to 80 atom% of Ti and the remaining portion including Mo and unavoidable impurities. Hydrogen, as one of the unavoidable impurities, is 10 mass ppm or less. Furthermore, the MoTi target of the invention is obtained by a step of conducting a heat treatment to a MoTi sintered body under a condition of a pressure of 100 Pa or less, 800 DEG C or higher and 0.5 hour or more.

Description

MoTi target and manufacturing method thereof

The present invention relates to a MoTi target used in a physical vapor deposition technique such as sputtering, and a method for producing the same.

In recent years, in a thin film electrode and a thin film wiring of a thin film transistor type liquid crystal display or the like which is a flat display device, a low-resistance pure metal film of Al, Cu, Ag, Au, or the like, or a main body thereof is used. Alloy film. However, in general, these films have problems in that any of heat resistance, corrosion resistance, and adhesion required as electrodes and wirings are deteriorated, or a diffusion layer is formed with other elements to lose desired electrical characteristics.

Therefore, in order to solve such problems, pure Mo or a Mo alloy as a high melting point metal is used as a base film or a cover film with respect to a substrate. In particular, a MoTi film is proposed as a wiring of Al or a Cu-based film or a base film or a cover film of an electrode film, and a target such as Patent Document 1 or Patent Document 2 is proposed as a target for forming the MoTi film.

In the manufacturing method of the example of the patent document 1 or the patent document 2, the MoTi target which is made from the MoTi sintered body which uses the Mo powder of a predetermined particle diameter and the Ti powder as a raw material powder is described. Made by pressure sintering. The MoTi target disclosed in Patent Document 1 is a target excellent in that, when sputtering is formed, the generation of splash or particles can be remarkably reduced.

[Previous Technical Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2008-255440

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2007-297654

According to the discussion of the inventors of the present invention, it has been confirmed that the MoTi film obtained by sputtering the MoTi target disclosed in Patent Document 1 has an increased resistance value. In the case of being used as a wiring film or a base film or a cover film, the lower the resistance value, the better.

Further, it was confirmed that the film stress of the obtained MoTi film was increased. The increase in the film stress causes a problem such as peeling of the film in the next step of etching or cleaning, etc., resulting in a decrease in reliability of the electronic component.

An object of the present invention is to provide a MoTi target which can improve the problem of film peeling and which can maintain a low resistance value, and a method for producing the same, in view of the above problems.

The present inventors conducted a detailed investigation of a MoTi target for forming a thin film disclosed in Patent Document 1, and confirmed that the hydrogen content of the target exceeded 100 ppm by mass. Further, it was confirmed that the hydrogen caused the above-mentioned film peeling or an increase in the electric resistance value, and it was found that the above problem can be solved by lowering the hydrogen content of the MoTi target to be lower than the original, and the present invention has been completed.

That is, the present invention is a MoTi target having a composition containing 20 atom% to 80 atom% of Ti and the remainder containing Mo and unavoidable impurities, and hydrogen as one of the unavoidable impurities is 10 ppm by mass. the following.

Moreover, the MoTi target of the present invention can be controlled by a pressure of less than 100 Pa The MoTi sintered body was heat-treated under the conditions of a force of 800 ° C or more and 0.5 hour or more.

Further, the MoTi sintered body is preferably produced by the following steps: (1) a step of pulverizing Mo aggregates obtained by aggregating Mo primary particles into an average particle diameter of 10 μm or less to prepare Mo powder; (2) a step of preparing a Ti powder having an average particle diameter of 50 μm or less; (3) a step of preparing the MoTi mixed powder by mixing the Mo powder and the Ti powder in an amount of 20 atom% to 80 atom%; and (4) A step of preparing a MoTi sintered body by pressure-sintering the above MoTi mixed powder.

Further, the pressure sintering of the present invention is preferably carried out at a sintering temperature of 800 ° C to 1500 ° C and a pressure of 10 MPa to 200 MPa for 1 hour to 20 hours.

According to the present invention, since a MoTi target which limits the hydrogen content to the limit can be provided, in the case of using, for example, a MoTi film as a base film or a cover film of a wiring film or the like, the resistance value can be suppressed low, and The problem of film peeling is solved by reducing the film stress, and the industrial value in the manufacture of electronic parts is extremely great.

The present invention is characterized in that the hydrogen content which is one of the unavoidable impurities contained in the MoTi target is limited to 10 ppm by mass or less. Moreover, the present invention is also characterized in that MoTi is obtained as a limitation of the hydrogen content. The method of the target is performed by heat treatment under reduced pressure. Hereinafter, the characteristics of the MoTi target of the present invention will be described in detail.

Hydrogen which is one of the unavoidable impurities contained in the MoTi target of the present invention is limited to 10 ppm by mass or less. This is because, in the case where the hydrogen content is more than 10 ppm by mass, the stress released from the MoTi target in sputtering sometimes causes an increase in stress or specific resistance of the formed MoTi film. rise.

Here, in the next step of etching or cleaning as described above, there is a concern that an increase in film stress causes problems such as film peeling. Further, in the case of a base film or a cover film used as an electrode, it is preferable to have a low electric resistance similarly to the electrode, so that an increase in electrical resistivity is also a problem. Therefore, hydrogen which is an unavoidable impurity contained in the MoTi target of the present invention is limited to 10 ppm by mass or less. Further, it is more preferable to limit hydrogen to 5 ppm by mass or less.

Further, the MoTi target of the present invention has a Ti content of 20 atom% to 80 atom%. This is because the effect of improving the corrosion resistance of the film formed when the Ti content is less than 20 atom% is low, and when it exceeds 80 atom%, the etching property is lowered.

Further, the MoTi target of the present invention has a uniform structure, whereby the surface of the target is uniformly sputtered during sputtering, and the effect of suppressing problems such as nodule or particles can be expected.

Next, a method of producing the MoTi target of the present invention will be described in detail.

In the method for producing a MoTi target of the present invention, the MoTi sintered body is subjected to a pressure of less than 100 Pa, a temperature of 800 ° C or more, and 0.5 hour or more. Heat treatment is performed, whereby the hydrogen content in the MoTi sintered body can be lowered. Further, in the present invention, oxidation or nitridation of the MoTi sintered body can be suppressed by performing heat treatment under the conditions.

When the heat treatment temperature is lower than 800 ° C, it is difficult to sufficiently dehydrogenate the sintered body. Therefore, in the present invention, the heat treatment temperature is set to 800 ° C or higher. On the other hand, in the case where the heat treatment temperature is higher than 1650 ° C, Ti is melted, so that it is preferred to carry out the heat treatment temperature at 1650 ° C or lower.

Further, in the case where the pressure in the furnace exceeds 100 Pa, it is difficult to sufficiently perform dehydrogenation of the sintered body, and therefore, in the present invention, heat treatment is performed under a pressure of less than 100 Pa. On the other hand, decompression from 10 ^-4 Pa is not practical in actual production. It is preferred to reduce the pressure to 10 ^-3 Pa.

In addition, when the heat treatment time is 0.5 hours or less, the progress of dehydrogenation of the sintered body is insufficient, and therefore, in the present invention, it is set to 0.5 hour or longer. On the other hand, heat treatment for more than 40 hours is not practical in actual production. It is preferably set to be within 30 hours.

In the present invention, the MoTi sintered body is preferably produced through the following steps (1) to (4).

(1) A step of preparing a Mo powder by pulverizing a Mo aggregate containing Mo primary particles to an average particle diameter of 10 μm or less

In the present invention, it is preferable to pulverize the Mo aggregates in which the Mo primary particles having a particle diameter of about 5 μm are connected into a mesh shape, for example, by a jet mill or an impact mill. The particle size is 10 μm or less. Thereby, in the present invention, the dispersibility of Mo can be improved when mixed with the Ti powder. Here, the average particle diameter of the pulverized Mo powder is more than 10 μm. In the case where the coarse Mo aggregate is contained in the target, there is a possibility that the sintering is not sufficiently performed and the relative density is lowered, or the Ti phase is difficult to form in the porous portion of the Mo aggregate, causing segregation of the composition. , thus hindering the dispersion of Mo. Therefore, in the present invention, it is preferred to pulverize to an average particle diameter of 10 μm or less.

Further, in the Mo powder used in the present invention, the Mo primary particles themselves may be used as long as the particle diameter is 10 μm or less.

(2) a step of preparing a Ti powder having an average particle diameter of 50 μm or less and

(3) A step of preparing the MoTi mixed powder by mixing the Mo powder and the Ti powder in an amount of 20 atom% to 80 atom% of Ti

Next, Ti powder having an average particle diameter of 50 μm or less is prepared, and the Ti powder and the pulverized Mo powder are, for example, a V-type mixer, a cross rotary mixer, a ball mill, or the like, to contain 20 atom%. A mixture of ~80 atom% of Ti is mixed, whereby a uniform MoTi mixed powder can be obtained. Here, the average particle diameter of the Ti powder is 50 μm or less because it is difficult to obtain a uniform fine structure in the MoTi sintered body when the average particle diameter of the Ti powder is more than 50 μm.

(4) A step of pressure-sintering the above MoTi mixed powder to produce a MoTi sintered body

In the present invention, sintering of MoTi is performed by pressure sintering. The pressure sintering is preferably carried out, for example, by hot isostatic pressing or hot pressing at a sintering temperature of 800 ° C to 1500 ° C and a pressure of 10 MPa to 200 MPa for 1 hour to 20 hours.

The choice of these conditions depends on the equipment for pressure sintering. For example, hot equal pressure is easy to apply to low temperature and high pressure conditions, and hot pressing is easy to apply to high temperature and low pressure conditions. In the present invention, in the pressure sintering, in order to suppress the reaction between the pressurized container and the Ti powder at a high temperature, it is preferred to use a low temperature and high pressure heat equalization pressure.

Further, when the sintering temperature is less than 800 ° C, sintering is difficult to carry out and is not practical. On the other hand, when the sintering temperature exceeds 1500 ° C, the tolerable device is limited, and the crystal growth of the sintered body becomes conspicuous, and it is difficult to obtain a uniform fine structure.

Further, when the pressing force is 10 MPa or less, sintering is difficult to carry out without being practical. On the other hand, if the applied pressure exceeds 200 MPa, there is a problem that the tolerable device is limited.

Further, when the sintering time is 1 hour or less, it is difficult to sufficiently carry out the sintering. On the other hand, if the sintering time exceeds 20 hours, this should be avoided in terms of manufacturing efficiency.

Further, when pressure sintering is performed by hot pressing or hot pressing, after the MoTi mixed powder is filled in a pressurized container or a press mold, it is preferred to perform degassing under reduced pressure while heating. The degassing under reduced pressure is preferably carried out at a heating temperature of from 100 ° C to 600 ° C under a reduced pressure of less than atmospheric pressure (101.3 kPa). This is because the oxygen of the obtained sintered body can be reduced.

The relative density of the MoTi target of the present invention is preferably 95% or more. When the relative density of the target material is lowered, the voids present in the target are increased, and in the sputtering step based on the void, the formation of agglomerates which cause abnormal discharge is likely to occur. In particular, when the relative density is less than 95%, the probability of generating agglomerates becomes high, so that the relative density is preferably 100% or more.

The relative density of the present invention refers to a value obtained by multiplying a value obtained by dividing the bulk density measured by the Archimedes method by a theoretical density, which is the MoTi according to the present invention. The composition ratio of the target is obtained by weighting the calculated weight ratio of the elemental monomers obtained. Specifically, values of 10.22 × 10 ³ kg/m ³ and 4.50 × 10 ³ kg/m ³ are used as the density of Mo and Ti, respectively, and the elemental monomer calculated as the mass ratio obtained by the composition ratio is used. The value obtained by weighted averaging is used as the value of the theoretical density. The density of the MoTi alloy is higher than that of the Mo phase and the Ti phase independent compound, and thus the MoTi target of the present invention more preferably has a relative density of more than 100%.

[Example 1]

Hereinafter, examples of the invention will be described.

First, a Mo agglomerate obtained by aggregating Mo primary particles having a particle diameter of 5 μm was pulverized by a jet mill to obtain a pulverized Mo powder having an average particle diameter of 8 μm. Next, a Ti raw material powder having an average particle diameter of 25 μm was prepared. Then, the obtained pulverization-treated Mo powder and Ti raw material powder are mixed by a cross rotary mixer so as to be 50% Mo-50% Ti in atom%, and filled into a soft steel system. After the pressure vessel is placed, the upper cover having the degassing port is welded to the pressurized container. Next, a MoTi sintered body was obtained by vacuum degassing at a temperature of 450 ° C and maintaining a heat equalization treatment for 5 hours under the conditions of a temperature of 800 ° C and a pressure of 118 MPa.

Then, the obtained MoTi sintered body was subjected to heat treatment at a vacuum of 10 ^-2 Pa for 20 hours at respective temperatures of 300 ° C, 500 ° C, 800 ° C, 1100 ° C, and 1400 ° C to obtain a MoTi target. Further, for comparison, a MoTi target which was not subjected to heat treatment was prepared by the same method as described above.

Test pieces were obtained from each of the MoTi targets obtained above by mechanical processing, and the hydrogen content and the relative density were measured. Here, the relative density is a value obtained by multiplying a value obtained by dividing the bulk density measured by the Archimedes method by a theoretical density, which is the MoTi according to the present invention. The composition ratio of the target is obtained by weighting the calculated weight ratio of the elemental monomers obtained.

Further, the hydrogen content in the MoTi target was measured by a hydrogen analyzer (manufactured by Horiba, Ltd., model: EMGA-921) using a thermal conductivity method. Further, the mixed MoTi mixed powder used in the experiment had a hydrogen content of 131 ppm.

As shown in Table 1, it was confirmed that the MoTi target of the present invention has a hydrogen content of 10 ppm by mass or less by a heat treatment under a predetermined reduced pressure.

[Example 2]

Mo agglomerate formed by agglomerating Mo primary particles with a particle size of 5 μm It was pulverized by a jet mill to obtain a pulverized Mo powder having an average particle diameter of 8 μm. Next, a Ti raw material powder having an average particle diameter of 25 μm was prepared. Then, the obtained pulverization-treated Mo powder and the Ti raw material powder are mixed in a cross-rotating mixer so as to be 50% Mo-50% Ti in atom%, and then filled in a soft steel pressurized container, and then An upper cover having a degassing port is welded to the pressurized container. Next, a MoTi sintered body was obtained by vacuum degassing at a temperature of 450 ° C and maintaining a heat equalization treatment for 5 hours under the conditions of a temperature of 1000 ° C and a pressure of 118 MPa.

Then, the obtained sintered body was subjected to heat treatment at a temperature of 1000 ° C and 1150 ° C for a vacuum degree of 10 ^-2 Pa, a heat treatment time of 5 hours, and 10 hours, thereby obtaining a MoTi target.

Test pieces were obtained from each of the MoTi targets obtained above by mechanical processing, and the hydrogen content and the relative density were measured. Here, the relative density is a value obtained by multiplying a value obtained by dividing the bulk density measured by the Archimedes method by a theoretical density, which is the MoTi according to the present invention. The composition ratio of the target is obtained by weighting the calculated weight ratio of the elemental monomers obtained.

Further, the hydrogen content in the MoTi target was measured by a hydrogen analyzer (manufactured by Horiba, Ltd., model: EMGA-921) using a thermal conductivity method. Further, the hydrogen content of the mixed MoTi mixed powder used in the experiment was 30 ppm by mass.

As shown in Table 2, it was confirmed that the MoTi target of the present invention can reduce the hydrogen content to 10 ppm by mass or less by heat treatment under a predetermined reduced pressure.

A test piece was taken from the MoTi target of sample No. 6 to sample No. 11 obtained above by mechanical processing, and the microstructure was observed by an optical microscope. The results are shown in Fig. 1.

From this result, it was confirmed that the heat treatment temperature was increased, and as the time was extended, the alloying was performed, and the structure became uniform.

[Example 3]

A MoTi target having a diameter of 164 mm and a thickness of 5 mm was cut out from the MoTi target of sample No. 1 and sample No. 6 obtained by the above-described mechanical processing, and brazed on a copper backing plate ( Backing plate). Then, each of the MoTi targets obtained above was mounted on a sputtering apparatus (manufactured by Canon-anelva Co., Ltd., model: C-3010) to form a MoTi film having a thickness of 300 nm on the glass substrate. . The sputtering discharge condition at this time was set to 1000 W in an argon atmosphere at a pressure of 0.5 Pa.

The stress and electrical resistivity of the MoTi film obtained above were measured using a 4-terminal thin film resistivity meter (manufactured by Dins Co., Ltd., model: MCP-T400). Moreover, the film stress is a 300 nm MoTi film formed on the Si wafer, and the warpage is performed using a laser displacement meter (浜松光电) (Manufactured by HAMAMATSU Photonics) Co., Ltd., model: PM-3). The stress and electrical resistivity of the formed MoTi film are shown in Table 3.

As shown in Table 3, the MoTi target of the present invention has a hydrogen content as low as 10 ppm by mass or less, and a stress and resistance of the MoTi film formed by sputtering, compared with the comparative example in which the heat treatment of the sintered body is not performed. The rate is small, thereby obtaining a high-performance MoTi film. According to the MoTi target of the present invention, a film which can be formed as a wiring film of an electronic component or a base film or a cover film thereof can be confirmed.

Fig. 1 is a photograph obtained by observing a target of sample No. 6 to sample No. 11 with an optical microscope.

Claims (3)

A MoTi target having a composition containing 20 atom% to 80 atom% of Ti and having a remainder containing Mo and unavoidable impurities, and hydrogen as one of the unavoidable impurities is 10 mass ppm or less. A method for producing a MoTi target, comprising the step of heat-treating a MoTi sintered body under a pressure of less than 100 Pa, 800 ° C or more, and 0.5 hour or more. The method for producing a MoTi target according to the second aspect of the invention, wherein the MoTi sintered body is produced by the following steps: (1) Mo aggregates obtained by aggregating Mo primary particles are pulverized into an average particle diameter of 10 a step of preparing a Mo powder of μm or less; (2) a step of preparing a Ti powder having an average particle diameter of 50 μm or less; and (3) adding the Mo powder and the Ti powder to a Ti content of 20 atom% to 80 atom%. a step of preparing a MoTi mixed powder by mixing; and (4) a step of producing a MoTi sintered body by press-sintering the MoTi mixed powder.