JP2019131849A - Sputtering target, and method for producing sputtering target - Google Patents

Abstract

To provide a sputtering target that prevents the occurrence of abnormal discharge even when sputtering deposition is performed for a long time, and allows stable deposition, and also allows deposition of a nitrogen-containing chromium film with a uniform nitrogen concentration with little variation, and a method for producing a sputtering target.SOLUTION: A sputtering target contains a metal chromium phase and a chromium nitride phase. In a host phase of the metal chromium phase, the chromium nitride phase is dispersed.SELECTED DRAWING: None

Description

  The present invention relates to a sputtering target used when forming a nitrogen-containing chromium film, and a method for manufacturing the sputtering target.

The above-described nitrogen-containing chromium film is, for example, as shown in Patent Document 1, a photomask used when forming a circuit pattern of a semiconductor integrated circuit, or a pressure sensor, an acceleration sensor, or the like as shown in Patent Document 2, for example. Is used as a thin film for strain gauges.
As a method for forming such a nitrogen-containing chromium film, as shown in Patent Documents 1 and 2, a sputtering method using a sputtering target has been proposed.

Here, paragraph No. 0006 of Patent Document 1 includes, as a conventional technique, a sputtering target composed of a sintered body obtained by mixing and sintering a metal chromium powder and a chromium nitride powder, and a sintering target obtained by sintering only the chromium nitride powder. A sputtering target comprising a ligation is disclosed. And, in the sputtering target made of a sintered body obtained by mixing and sintering the metal chromium powder and the chromium nitride powder, there is a problem that the dispersion of the chromium nitride powder becomes non-uniform and the distribution of nitrogen is not uniform. Pointed out. Further, it is pointed out that a sputtering target made of a sintered body obtained by sintering only chromium nitride powder has a problem that processing defects frequently occur and the manufacturing yield decreases.
And in patent document 1, the sputtering target which consists of the sintered compact which formed the chromium nitride powder which nitrided the surface of the metal chromium powder, and sintered this is proposed.

Japanese Patent Laid-Open No. 08-003737 Japanese Patent Laid-Open No. 07-306002

  By the way, in the sputtering target proposed in Patent Document 1, since the chromium nitride powder obtained by nitriding the surface of the metal chromium powder is sintered, the metal chromium phase is dispersed in the chromium nitride phase. ing. Here, in the above-mentioned chromium nitride powder, since the surface is made of chromium nitride, the sinterability tends to be insufficient, and when sputter film formation is performed for a long time, particles are generated, abnormal discharge is generated, and stable. As a result, there is a possibility that the film cannot be formed.

  The present invention has been made in view of the above-described circumstances, and can suppress the occurrence of abnormal discharge even when sputter film formation is performed for a long time, can stably form a film, and It is an object of the present invention to provide a sputtering target capable of forming a nitrogen-containing chromium film having a uniform nitrogen concentration with little variation in nitrogen, and a method for manufacturing the sputtering target.

  In order to solve the above problems, a sputtering target of the present invention is a sputtering target having a metallic chromium phase and a chromium nitride phase, wherein the chromium nitride phase is dispersed in the matrix phase of the metallic chromium phase. It is characterized by that.

  According to the sputtering target of the present invention, since the chromium nitride phase is dispersed in the matrix phase of the metal chromium phase, the metal chromium phases have built a network and are surely sintered. Will be. Therefore, even when the sputter film formation is performed for a long time, the occurrence of abnormal discharge can be suppressed, and the sputter film formation can be performed stably.

The sputtering target manufacturing method of the present invention is a sputtering target manufacturing method for manufacturing the above-described sputtering target, and a sintering raw material powder forming step of obtaining a sintering raw material powder by mixing chromium nitride powder and metal chromium powder. If, anda sintering step to obtain a heated and sintered body while pressurizing the sintering raw material powder, in the sintering raw material powder forming step, the average particle diameter D _N of the chromium nitride powder metal the ratio _D N / _{D M} and the average particle diameter _{D M} of the chromium powder is less than 1, and the ratio _V N / _{V M} of the volume _{V M} of the metal chromium powder and the volume _{V N} of the chromium nitride powder 3 It is characterized by being less than.

According to the manufacturing method of the sputtering target of the present invention, the sintering raw material powder forming step, the ratio D _{N /} D _M and the average particle diameter D _M of the metallic chromium powder with an average particle diameter D _N of the chromium nitride powder is less than 1, and, since the three less than the ratio V _{N /} V _M of the volume V _M of the metal chromium powder and the volume V _N of the chromium nitride powder, covering the chromium nitride powder is deformed metallic chromium powder Then, the metal chromium powders are sintered together, and a sintered body having a structure in which the chromium nitride phase is dispersed in the matrix phase of the metal chromium phase can be obtained. Therefore, the metal chromium phases can construct a network and can be surely sintered. Thereby, even when sputter deposition is performed for a long time, the occurrence of abnormal discharge can be suppressed, and a sputtering target capable of stably performing sputter deposition can be manufactured.

  According to the present invention, even when sputter deposition is performed for a long time, it is possible to suppress the occurrence of abnormal discharge, to stably form a film, and to have a uniform nitrogen concentration with a small variation in nitrogen. A sputtering target capable of forming a chromium-containing film and a method for manufacturing the sputtering target can be provided.

It is explanatory drawing which shows the measurement position of the nitrogen concentration in the sputter | spatter surface of the sputtering target whose target shape is a flat plate and a sputter | spatter surface makes circular. It is explanatory drawing which shows the measurement position of the nitrogen concentration in the sputter | spatter surface of the sputtering target whose target shape is a flat plate and a sputter | spatter surface makes a rectangle. It is explanatory drawing which shows the measurement position of the nitrogen concentration in the sputtering surface of the sputtering target whose target shape is a cylinder and whose sputtering surface is a cylindrical outer peripheral surface. It is a flowchart which shows the manufacturing method of the sputtering target which concerns on one Embodiment of this invention.

  Below, the sputtering target which is one Embodiment of this invention, and the manufacturing method of a sputtering target are demonstrated. In addition, the sputtering target which is this embodiment is used when forming a nitrogen-containing chromium film.

  The sputtering target according to the present embodiment is made of a sintered body of metal chromium powder and chromium nitride powder, and has a metal chromium phase and a chromium nitride phase, and the chromium nitride phase is contained in the matrix phase of the metal chromium phase. It is a distributed organization.

And in the sputtering target which is this embodiment, the dispersion | variation in the nitrogen content in a sputtering surface is 25% or less.
Note that the variation in the nitrogen content on the sputtering surface is obtained by the following equation.
(Variation)% = standard deviation / average value x 100

  Here, in the present embodiment, when the shape of the sputtering target is a flat plate and the sputtering surface is circular, as shown in FIG. 1, it passes through the center (1) of the circle and the center of the circle. The nitrogen content is measured at five points (2), (3), (4), and (5) on the outer peripheral portions (2), (3), (4), and (5) on two straight lines orthogonal to each other, and the variation in the nitrogen content on the sputtering surface is obtained.

  Further, when the shape of the sputtering target is a flat plate and the sputtering surface is rectangular, as shown in FIG. 2, the intersection (1) where the diagonal lines intersect and the corners (2), (3) on each diagonal line, as shown in FIG. , (4), and (5), the nitrogen content is measured, and the variation of the nitrogen content on the sputtering surface is obtained.

  Further, when the shape of the sputtering target is a cylinder and the sputtering surface is a cylindrical outer peripheral surface, as shown in FIG. 3, (1) and (2) at intervals of 90 ° from the half point in the axis O direction to the outer peripheral direction. , (3), (4), and nitrogen content is measured at a total of 8 points of (5), (6), (7), (8) at intervals of 90 ° in the outer peripheral direction at the end in the axis O direction Then, the variation in the nitrogen content on the sputtering surface is obtained.

Here, the chromium nitride phase is mainly composed of CrN or Cr ₂ N. In the sputtering target, a chromium oxide phase may be present together with the chromium nitride phase.
Moreover, in the sputtering target which is this embodiment, nitrogen content is made into the range of 1 mass% or more and 15 mass% or less.
Furthermore, in the sputtering target which is this embodiment, the relative density is 98% or more.

Next, the manufacturing method of the sputtering target which is this embodiment is demonstrated.
First, chromium nitride powder and metal chromium powder are mixed to obtain sintered raw material powder (sintered raw material powder forming step S01).
Here, it is preferable to use a metal chromium powder having a purity of 99.99% or more (4N) or more by mass ratio.
As the chromium nitride powder, CrN powder, Cr ₂ N powder, and it is possible to use these mixed powder. As the CrN powder and the Cr ₂ N powder, those having a purity of Cr in the metal component of 99% or more (2N) or more are preferably used.
In addition to chromium metal powder and chromium nitride powder, chromium oxide powder may be added. As the chromium oxide powder, for example, Cr ₂ O ₃ powder with a purity of Cr in the metal component of 99% or more (2N) or more can be used.

In this sintering raw material powder forming step S01, the ratio D _{N /} D _M and the average particle diameter D _M of the average particle diameter D _N and chromium metal powder chromium nitride powder of less than 1.
Further, in the sintering raw material powder forming step S01, and the ratio _V N / _{V M} of the volume _{V M} of the volume _{V N} and chromium metal powder chromium nitride powder below 3.
Here, the nitrogen content in the sintering raw material powder, by adjusting the volume ratio V _{N /} V _M of the above, so that the nitrogen content in the sputtering target is adjusted.

The weighed chromium nitride powder and metal chromium powder are mixed by a mixing device such as a ball mill, a Henschel mixer, a blender or the like to obtain a raw material powder. At this time, in order to prevent oxidation of the metal chromium powder, the atmosphere in the mixing apparatus is preferably an inert gas atmosphere such as Ar.
In this sintering raw material powder forming step S01, the nitrogen content in the sintered body can be made uniform by sufficiently mixing the chromium nitride powder and the metal chromium powder.

Next, the above sintered raw material powder is sintered by pressurizing and heating to obtain a sintered body (sintering step S02).
In this sintering step S02, sintering may be performed using a hot press apparatus. In this case, it is preferable to carry out the sintering under the conditions of 1100 ° C. to 1400 ° C., holding time of 2 hours to 5 hours, and pressure of 20 MPa to 40 MPa. In addition, it is preferable to make sintering temperature into the range of 1250 degreeC or more and 1350 degrees C or less.
Further, in the sintering step S02, sintering may be performed using a HIP device. In this case, after filling the sintered raw material powder, degassing treatment is performed under the conditions of a vacuum degree of 1.5 Pa or less, a holding temperature of 500 ° C. or more and 600 ° C. or less, and a holding time of 5 hours or more. It is preferable to carry out under the conditions of a temperature of 1100 ° C. to 1400 ° C., a holding time of 1 hour to 3 hours, and a pressure of 90 MPa to 110 MPa. In addition, it is preferable to make sintering temperature into the range of 1200 to 1300 degreeC.

And the sintered compact obtained by sintering process S02 is machined so that it may become a predetermined dimension (machining process S03).
The sputtering target which is this embodiment is manufactured by the above.

  In the sputtering target according to the present embodiment configured as described above, the chromium nitride phase is dispersed in the matrix phase of the metallic chromium phase, and the metallic chromium phases construct a network. In addition, even when the chromium metal is sufficiently bonded by sintering and sputter deposition is performed for a long time, the occurrence of abnormal discharge can be suppressed and stable sputter deposition can be performed. .

  And in the sputtering target which is this embodiment, since the dispersion | variation in nitrogen content in a sputtering surface is 25% or less, it becomes possible to form a nitrogen-containing chromium film | membrane with uniform nitrogen concentration.

Moreover, in the sputtering target which is this embodiment, since nitrogen content is made into the range of 1 mass% or more and 15 mass% or less, a nitrogen-containing chromium film | membrane can be formed reliably.
Furthermore, since the relative density of the sputtering target according to the present embodiment is 98% or more, the occurrence of abnormal discharge during sputtering film formation can be further suppressed, and stable sputtering film formation can be achieved.

According to the manufacturing method of a sputtering target which is the present embodiment, in the sintering raw material powder forming step S01, the ratio D _N between the average particle diameter D _M of the average particle diameter D _N and chromium metal powder chromium nitride powder / a D _M is less than 1, and, since the three less than the ratio V _{N /} V _M of the volume V _M of the volume V _N and chromium metal powder chromium nitride powder, chromium nitride powder is deformed metallic chromium powder The metal chromium powders are sintered together, and a sintered body having a structure in which the chromium nitride phase is dispersed in the matrix phase of the metal chromium phase can be obtained. Therefore, even when sputtering film formation is performed for a long time, the generation of abnormal discharge can be suppressed, and a sputtering target capable of performing stable sputtering film formation can be manufactured.
Further, the chromium nitride powder is uniformly dispersed, and the variation in the nitrogen content on the sputtering surface can be reduced to 25% or less.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
In this embodiment, although it demonstrated as what performs sintering using a hot press apparatus or a HIP apparatus, it is not limited to this, You may use another sintering apparatus.

  Below, the result of the confirmation experiment performed in order to confirm the effectiveness of this invention is demonstrated.

As raw material powder, metal chromium powder (purity: 99.9 mass% or more), CrN powder (purity of Cr in metal component: 99 mass% or more), Cr ₂ N powder (purity of Cr in metal component: 99 mass% or more) , Cr ₂ O ₃ powder (purity of Cr in metal component: 99 mass% or more, average particle size 3 μm) was prepared.
Then, the average particle diameter of the metal chromium powder shown in Table 1, CrN powder, Cr 2 _N powder were mixed at a volume ratio shown in Table 1. In Examples 11 and 12, the amount of Cr ₂ O ₃ powder described in Table 1 was added.
Moreover, in the prior art, nitriding treatment was performed on the metal chromium powder, and a metal chromium powder having a chromium nitride layer formed on the surface was prepared. In the nitriding treatment, the temperature was raised to 900 ° C. after vacuum argon substitution in a rotary kiln furnace, and then a mixed gas of argon gas and nitrogen gas was flowed so as to obtain the nitrogen concentration of the conventional example, followed by heating for 30 minutes.

  These raw material powders are put into a polyethylene container (10 L) of a dry ball mill apparatus having an Ar gas atmosphere. At this time, 5 kg of zirconia balls having a diameter of 5 mm and 5 kg of zirconia balls having a diameter of 10 mm were placed in a polyethylene container. And it mixed for 18 hours at the rotation speed 73rpm. This obtained the sintering raw material powder.

  And as shown in Table 2, by sintering by the HIP method or the hot press (HP) method and machining the obtained sintered body, a disk shape (diameter 6 inches, thickness 6 mm), Alternatively, a sputtering target having a cylindrical shape (an outer diameter of 160 mm, an inner diameter of 135 mm, and a length of 600 mm) was obtained.

In the HIP method, the sintering conditions were a holding temperature of 1300 ° C., a pressure of 98 MPa, and a holding time of 2 hours.
In the hot press (HP) method, the sintering conditions were a holding temperature of 1350 ° C., a pressure of 35 MPa, and a holding time of 3 hours.

  About the sputtering target obtained as mentioned above, the following items were evaluated.

(Composition of sputtering target)
The nitrogen content in the sputtering target was measured by an inert gas melting-thermal conductivity detection method, and the balance was Cr. The oxygen content was measured by an inert gas melting-heat conduction detection method. The evaluation results are shown in Table 2.

(Relative density of sputtering target)
The density was calculated from the weight and dimensions. _{^{Then, Cr: 7.19g / cm 3,}} Cr 2 N: 6.51g / cm 3, CrN: 5.90g / cm 3, Cr 2 O 3: as 5.21 g / cm ^3, to calculate the theoretical density, The relative density was calculated.
As a result of the measurement, the relative density of all the produced sputtering targets was 95% or more.

(Relative density of sputtering target)
The structure of the sputtering target was observed. Using EPMA (Electron Probe Microanalyzer) JXA9500F, element mapping was performed at an acceleration voltage of 15 kV, and the structure was observed.
Here, the metal chromium phase is the parent phase, and the chromium nitride phase dispersed in the metal chromium phase is “A”, the chromium nitride phase is the parent phase, and the metal chromium phase is dispersed in the chromium nitride phase. In Table 2, “B” was used for the sample and “C” for the single chromium nitride phase.

(Variation of nitrogen content)
In a disk-shaped sputtering target, as shown in FIG. 1, the nitrogen content is measured by an inert gas melting-thermal conductivity detection method at five measurement points (1) to (5) in the sputtering surface. did.
In the cylindrical sputtering target, as shown in FIG. 3, the nitrogen content was measured by an inert gas melting-thermal conductivity detection method at eight measurement points (1) to (8) in the sputtering surface. .
And the dispersion | variation in nitrogen content was evaluated by the following formula | equation.
(Variation)% = standard deviation / average value x 100

(Number of abnormal discharges)
About the obtained sputtering target, the frequency | count of abnormal discharge generation | occurrence | production at the time of sputtering was measured in the following procedures.
The disc-shaped sputtering target was mounted on a Cu backing plate, and a film formation test was performed under the following film formation conditions.
Ultimate vacuum: 7 × 10 ⁻⁴ Pa
Gas flow rate: Ar 50sccm
Sputtering atmosphere: 0.67Pa
Power: 500W
Total pressure: 0.4Pa

In addition, a cylindrical sputtering target was mounted on a SUS backing tube, and a film formation test was performed under the following film formation conditions.
Ultimate vacuum: 7 × 10 ⁻⁴ Pa
Gas flow rate: Ar 50sccm
Sputtering atmosphere: 0.67Pa
Power: 1000W

  Sputtering was performed for 12 hours under the above film forming conditions, and the number of occurrences of abnormal discharge was automatically measured by an arcing counter attached to the sputtering power supply device during the subsequent 6 hours of sputtering.

  In the conventional examples 1 and 2 using a metal chromium powder that has been nitrided with a chromium nitride layer formed on the surface of the metal chromium powder, the chromium metal phase has a structure in which the metal chromium phase is dispersed. As a result, the number of abnormal discharges was extremely large, and it was not possible to carry out stable sputtering film formation.

In Comparative Examples 1-5 and 7 in which the particle diameter ratio and volume ratio of the metal chromium powder and the chromium nitride powder do not satisfy the scope of the present invention, the metal chromium phase has a structure in which the metal chromium phase is dispersed As a result, the number of abnormal discharges increased, and it was not possible to carry out sputter deposition stably.
In Comparative Example 6 using only the chromium nitride powder, the number of abnormal discharges increased, and it was not possible to stably perform the sputtering film formation.

  On the other hand, in Example 1-12 of the present invention in which the ratio of the particle size of the metal chromium powder to the chromium nitride powder and the volume ratio satisfy the scope of the present invention, the structure in which the chromium nitride phase is dispersed in the metal chromium phase Thus, the number of abnormal discharges was small, and the sputter deposition could be performed stably.

  As described above, according to the example of the present invention, even when sputter deposition is performed for a long time, the occurrence of abnormal discharge can be suppressed, stable deposition can be performed, and variation in nitrogen is small. It was confirmed that a sputtering target capable of forming a nitrogen-containing chromium film having a uniform nitrogen concentration can be provided.

Claims (2)

A sputtering target having a metallic chromium phase and a chromium nitride phase,
The sputtering target, wherein the chromium nitride phase is dispersed in a matrix phase of the metal chromium phase. It is a manufacturing method of the sputtering target which manufactures the sputtering target of Claim 1, Comprising:
There are a sintering raw material powder forming step of obtaining a sintered raw material powder by mixing chromium nitride powder and metal chromium powder, and a sintering step of obtaining a sintered body by heating the sintered raw material powder while applying pressure. And
In the sintering raw material powder forming step, the average particle diameter D _N of chromium nitride powder ratio D _{N /} D _M and the average particle diameter D _M of the metallic chromium powder is less than 1, and said chromium nitride powder manufacturing method of a sputtering target, characterized in that the ratio V _{N /} V _M of the volume V _N and the volume V _M of the metallic chromium powder with less than 3.

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