Preparation method of ruthenium sputtering target material

Abstract

The invention relates to the technical field of magnetron sputtering, and provides a preparation method of a ruthenium sputtering target material. The method comprises the following steps: sequentially carrying out hydrogen introduction reduction treatment, crushing and sieving on ruthenium powder to obtain reduced ruthenium powder; and the reduced ruthenium powder is sequentially subjected to compression molding, cold isostatic pressing treatment and sintering treatment, and the ruthenium sputtering target material is obtained. According to the method, the technical problems that the ruthenium sputtering target material is high in oxygen content and random in grain orientation in a traditional powder metallurgy process are effectively solved by combining a dual deoxidization mechanism of'hydrogen feeding reduction-hydrogen sintering 'and cooperative regulation and control of cold isostatic pressing treatment and sintering process parameters. Results of the embodiment show that the ruthenium sputtering target material prepared by the method can realize the following performance indexes: the purity is greater than or equal to 99.95%, the oxygen content is less than or equal to 20 ppm, the average grain size is less than or equal to 2 microns, the density is greater than or equal to 99%, the required specific crystallographic orientation can be stably formed, and a foundation is laid for subsequent magnetron sputtering preparation of a high-performance film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetron sputtering, in particular to a preparation method of a ruthenium sputtering target. BACKGROUND

[0002] Precious metal sputtering target is a kind of high-purity sputtering target with gold, silver, platinum group metals and their alloys as the main components, which is the key core material for preparing high-performance thin films in magnetron sputtering process. This kind of target has excellent electrical conductivity, chemical stability and oxidation resistance, and can realize uniform deposition of high-quality thin films, so it plays an irreplaceable role in high-tech fields such as microelectronic packaging, semiconductor devices, medical implant devices, high-end optical elements and new energy devices.

[0003] Ruthenium is one of the platinum group precious metal elements. The ruthenium thin film deposited by magnetron sputtering technology can be used as an advanced diffusion barrier layer, adhesion layer or low resistance wire in the microelectronics field, and is also an important candidate material in data storage media. At present, the preparation process of ruthenium target for magnetron sputtering is mainly powder metallurgy. However, the raw material ruthenium powder used to prepare the target will be oxidized even at room temperature in air, and the degree of oxidation will increase with the increase of temperature. This characteristic makes the control of oxygen content in the whole process of ruthenium target preparation a core challenge to determine its quality and performance. At the same time, the grain orientation distribution of the ruthenium target directly determines the sputtering rate in the magnetron sputtering process and the growth mode of the thin film. If the grain orientation is chaotic, it may cause problems such as grain boundary defects and stress concentration in the thin film, thereby deteriorating the electrical conductivity, density and interface bonding force of the thin film; while when the grain orientation is highly preferred, it can promote the formation of a thin film with uniform structure and fine grains, thereby improving the electrical stability and service life of the thin film. Therefore, reducing the oxygen content of the ruthenium target and controlling the grain orientation of the target are prerequisites for inhibiting defects in the thin film and ensuring its excellent electrical conductivity and long-term stability, which is of great significance for promoting the application of ruthenium in advanced high-end device manufacturing.

[0004] A high-purity ruthenium target for sputtering and a preparation method thereof are provided in the related art, wherein the ruthenium powder is filled, pre-pressed and vacuum hot-pressed to obtain a ruthenium pre-target blank, then hot isostatic pressing sintering is performed, and finally the finished ruthenium target is obtained through machining. This method can adjust the size of the target, and is especially suitable for the preparation of large-size (diameter > 440 mm) high-purity ruthenium targets, but the preparation process is complicated, the equipment requirements are high, and the control of oxygen content is not involved. Another related technology provides a preparation method of a high-purity ruthenium sputtering target, wherein a powder metallurgy process is adopted to prepare the ruthenium target by direct vacuum hot pressing method. This method focuses on the forming process of the ruthenium target, and does not involve the control method of the grain orientation and internal oxygen content of the target.

[0005] In summary, there is an urgent need for a preparation method that can effectively reduce the oxygen content of the ruthenium target and control the grain orientation of the target. SUMMARY

[0006] Therefore, the application provides a preparation method of a ruthenium sputtering target.

[0007] In order to achieve the above-mentioned purposes, the application provides the following technical scheme. The application provides a preparation method of a ruthenium sputtering target, comprising the following steps: reducing ruthenium powder by hydrogen reduction treatment, crushing and sieving; The application further provides a ruthenium sputtering target prepared by the method.

[0008] Preferably, the hydrogen reduction treatment is performed at a temperature of 450-650℃ for 60-120 min.

[0009] Preferably, the sieving is graded sieving, and the mesh numbers of the sieves used in the graded sieving are 100#, 120#, 150#, 200#, 300# and 500# in sequence.

[0010] Preferably, the pressure of the compression molding is 20-30 MPa, and the pressure holding time is 120-300 s.

[0011] Preferably, the mold used in the compression molding is a circular mold, and the diameter of the mold is 20-45 mm.

[0012] Preferably, the plastic or rubber sleeve used in the cold isostatic pressing treatment is elastoplastic.

[0013] Preferably, the inert gas or nitrogen is introduced before the hydrogen is introduced in the heating stage.

[0014] Preferably, after the sintering treatment, the obtained ruthenium sputtering target is further subjected to mechanical polishing treatment.

[0015] Preferably, the ruthenium sputtering target has a purity of ≥ 99.95%, an oxygen content of ≤ 20 ppm, an average grain size of ≤ 2 μm, and a target density of ≥ 99%.

[0016] Preferably, the sputtering surface of the ruthenium sputtering target has a preferred orientation tending to {10-11} or {0002} direction.

[0017] The present application provides a preparation method of a ruthenium sputtering target, comprising the following steps: subjecting ruthenium powder to hydrogen reduction treatment, crushing and sieving in sequence to obtain reduced ruthenium powder; subjecting the reduced ruthenium powder to compression molding, cold isostatic pressing treatment and sintering treatment in sequence to obtain the ruthenium sputtering target; the pressure of the cold isostatic pressing treatment is 200-300 MPa, and the pressure holding time is ≥ 5 min; the sintering treatment is carried out under hydrogen atmosphere; the sintering treatment comprises a heating-up stage, a holding stage and a cooling-down stage; the heating-up rate of the heating-up stage is ≤ 10 ℃ / min; the temperature of the holding stage is 1000-1300 ℃, and the holding time is 60-90 min. The present application has the following beneficial effects: (1) The present application can directly remove the oxide layer adsorbed on the surface of the raw material ruthenium powder in the storage and transportation process through hydrogen reduction treatment; and the sintering process under hydrogen atmosphere can further inhibit the contact reaction of the ruthenium blank with oxygen in the high-temperature forming stage and reduce the generation of internal oxides. Compared with the traditional process which only relies on a single oxygen removal method (or does not specifically remove oxygen), the method of the present application can stably control the oxygen content of the ruthenium target below 20 ppm, achieving the design goal of low oxygen content. In summary, the present application effectively solves the problem of high oxygen content of the ruthenium target in the traditional powder metallurgy process through the dual oxygen removal mechanism of "hydrogen reduction-hydrogen sintering".

[0018] (2) The present application can effectively control the grain orientation of the ruthenium target by combining the synergistic regulation of the cold isostatic pressing treatment and the sintering treatment process parameters, and can guide the preferred orientation of the sputtering surface of the ruthenium target to tend to {10-11} or {0002} direction, effectively controlling the specific orientation of the ruthenium sputtering target, providing technical support for the differentiated demand of target orientation in different application scenarios (such as microelectronic diffusion barrier layer, data storage medium), and effectively solving the technical problem of random grain orientation of the ruthenium sputtering target in the traditional powder metallurgy process. The results of the embodiments show that the ruthenium sputtering target prepared by the present application can achieve the following performance indicators: purity ≥ 99.95%, oxygen content ≤ 20 ppm, average grain size ≤ 2 μm, and density ≥ 99%, and can stably form the required specific crystallographic orientation, laying a foundation for the subsequent preparation of high-performance thin films by magnetron sputtering. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 Process flow chart for preparing the ruthenium sputtering target according to the present application; Figure 2 Fracture scanning electron microscope image of the ruthenium target prepared for Example 1. DETAILED DESCRIPTION

[0020] The present application provides a preparation method of a ruthenium sputtering target, comprising the following steps: The ruthenium powder is sequentially subjected to hydrogen reduction treatment, crushing and sieving to obtain reduced ruthenium powder. The reduced ruthenium powder is sequentially subjected to compression molding, cold isostatic pressing treatment and sintering treatment to obtain the ruthenium sputtering target; the sintering treatment is carried out under hydrogen condition; the pressure of the cold isostatic pressing treatment is 200-300 MPa, and the pressure holding time is ≥5 min; the sintering treatment comprises a temperature rising stage, a temperature holding stage and a temperature falling stage; the temperature rising rate of the temperature rising stage is ≤10℃ / min; the temperature of the temperature holding stage is 1000-1300℃, and the temperature holding time is 60-90 min.

[0021] Figure 1 Process flow chart for preparing the ruthenium sputtering target according to the present application, which is described in detail below in combination with Figure 1 DETAILED DESCRIPTION

[0022] The present application sequentially subjects the ruthenium powder to hydrogen reduction treatment, crushing and sieving to obtain reduced ruthenium powder. In the present application, the purity of the ruthenium powder is preferably ≥99.95%; the temperature holding temperature of the hydrogen reduction treatment is preferably 450-650℃, and can be specifically 450℃, 550℃ or 650℃; the time of the hydrogen reduction treatment is preferably 60-120 min, and can be specifically 60 min, 90 min or 120 min; before the hydrogen reduction treatment, nitrogen or inert gas is preferably first introduced. The present application removes the oxygen adsorbed on the surface of the ruthenium powder through hydrogen reduction treatment.

[0023] The present application does not have special requirements for the crushing, and any method known to those skilled in the art can be used; the ruthenium powder is agglomerated after the hydrogen reduction treatment, and the present application crushes the agglomerated powder; the sieving is preferably graded sieving, and the mesh numbers of the sieves used for the graded sieving are 100#, 120#, 150#, 200#, 300# and 500# in sequence; the ruthenium powder under the 500# sieve is taken after the sieving and used.

[0024] After the reduced ruthenium powder is obtained, the reduced ruthenium powder is sequentially subjected to compression molding, cold isostatic pressing treatment and sintering treatment to obtain the ruthenium sputtering target. In the present application, the pressure of the compression molding is preferably 20-30 MPa, and can be specifically 20 MPa, 25 MPa or 30 MPa, and the pressure holding time is preferably 120-300 s, and can be specifically 120 s or 300 s; the compression molding is preferably performed by using an electric powder tablet press; the mold used in the compression molding is preferably a circular mold, and the mold diameter is preferably 20-45 mm, and can be specifically 30 mm or 45 mm; the material of the mold is preferably tool steel, and the hardness HRC of the circular mold used in the compression molding is preferably ≥65.

[0025] In the present application, the pressure of the cold isostatic pressing treatment is 200-300 MPa, and can be specifically 200 MPa, 250 MPa or 300 MPa, and the pressure holding time is ≥5 min, and can be specifically 5 min or 10 min; by controlling the pressure and pressure holding time of the cold isostatic pressing within the above range, the present application can optimize the density of the formed blank and minimize the internal porosity; and can also make the powder particles undergo plastic deformation and directional arrangement to form initial mechanical texture, and such preferred arrangement of the particles provides a basis for the grain orientation in the subsequent sintering process.

[0026] In the present application, the sleeve used in the cold isostatic pressing treatment is preferably a plastic or rubber sleeve with elastic-plasticity; in the specific embodiments of the present application, the ruthenium blank obtained by compression molding is preferably placed in a sleeve and then subjected to cold isostatic pressing treatment in a cold isostatic pressing machine; after the cold isostatic pressing treatment is completed, the sleeve is removed and the blank is demolded to obtain a high-density ruthenium blank.

[0027] In the present application, the sintering treatment comprises a temperature rising stage, a temperature holding stage and a temperature falling stage; before the temperature rising stage, preferably, inert gas or nitrogen is first introduced, in the specific embodiment of the present application, nitrogen is first introduced for 60 min, and then hydrogen is introduced; the temperature rising rate of the temperature rising stage is ≤10℃ / min, and specifically can be 1~10℃ / min; the temperature of the temperature holding stage is 1000~1300℃, and specifically can be 1000℃, 1100℃, 1200℃ or 1300℃, the temperature holding time is 60~90 min, and specifically can be 70 min, 80 min or 90 min, the hydrogen flow rate is ≤0.4 L / min, and specifically can be 0.1~0.4 L / min; the temperature falling stage is first air-cooled to below 500℃, and then furnace-cooled; the temperature falling rate of the air-cooling is ≤5℃ / min. In the sintering treatment process, atomic diffusion is enhanced at high temperature, pores are further shrunk or eliminated, and adjacent powder particles are combined through forming sintering necks and gradually grow into grains, therefore, the sintering temperature provides the driving force for atomic diffusion. And the surface energy and interface energy of grains with different crystal orientations are different, the specific orientation grains with lower surface energy / interface energy are more stable in thermodynamics when growing, and in a sufficient temperature holding time, these advantage orientation grains grow preferentially by engulfing the surrounding grains with higher energy. In summary, by controlling the temperature and temperature holding time and other parameters of sintering, the sputtering surface orientation of the ruthenium sputtering target can be controlled.

[0028] In the present application, after the sintering treatment, preferably, the obtained ruthenium sputtering target is further subjected to mechanical grinding and polishing treatment to prepare a ruthenium sputtering target with a required size.

[0029] In the present application, the purity of the ruthenium sputtering target is ≥99.95%, the oxygen content is ≤20 ppm, the average grain size is ≤2 μm, and the target density is ≥99%; the preferred orientation of the sputtering surface of the ruthenium sputtering target tends to be {10-11} or {0002} direction.

[0030] The technical solutions in the present application will be described clearly and completely below in combination with the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0031] Embodiment 1 (1) Select the purity of ruthenium powder above 99.95% for hydrogen reduction treatment, the holding temperature of hydrogen reduction treatment is 450℃, and the time is 120 min. After the end, the agglomerated ruthenium powder is broken and sieved, and the screen number is 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# screen is taken as the raw material.

[0032] (2) The ruthenium powder treated in step (1) is pressed into a shape by selecting a circular tablet steel mold, the mold size is 30 mm in diameter, the pressure is kept at 25 MPa during pressing, and the pressure holding time is 120 s.

[0033] (3) The ruthenium blank treated in step (2) is loaded into a package and placed in a cold isostatic pressing machine for cold isostatic pressing treatment, the pressure is kept at 200 MPa, and the pressure holding time is 5 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density ruthenium blank is prepared.

[0034] (4) The high-density ruthenium blank treated in step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, holding and cooling. In the heating stage, first pass through the inert gas nitrogen for 60 min, then open the hydrogen, and the heating rate is 10℃ / min; the holding temperature is 1000℃, the sintering time is 90 min, and the hydrogen flow is 0.4 L / min; in the cooling stage, first use air cooling, the cooling rate is 5 ℃ / min, and the cooling temperature is below 500℃, then the furnace is cooled. After densification sintering, the ruthenium target material of the required size is prepared by mechanical grinding and polishing treatment, and the fracture scanning electron microscope image is shown in Figure 2

[0035] Comparative Example 1 Comparative Example 1 is the same as Example 1 except that the ruthenium powder is not subjected to hydrogen reduction treatment, and the reducing hydrogen atmosphere is not passed during the densification sintering process. The specific steps are as follows: (1) Select the purity of ruthenium powder above 99.95% for hydrogen reduction treatment, the holding temperature of hydrogen reduction treatment is 450℃, and the time is 120 min. After the end, the agglomerated ruthenium powder is broken and sieved, and the screen number is 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# screen is taken as the raw material.

[0036] (2) The ruthenium powder treated in step (1) is pressed into a shape by selecting a circular tablet steel mold, the mold size is 30 mm in diameter, the pressure is kept at 25 MPa during pressing, and the pressure holding time is 120 s.

[0037] (3) The ruthenium blank treated in step (2) is loaded into a package and placed in a cold isostatic pressing machine for cold isostatic pressing treatment, the pressure is kept at 200 MPa, and the pressure holding time is 5 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density ruthenium blank is prepared.

[0038] ​(4) The high-density ruthenium blank after step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, sintering and cooling, and nitrogen is passed through the whole sintering process. The heating rate is 10 ℃ / min in the heating process; the temperature in the holding stage is 1000 ℃, the sintering time is 90 min, and the hydrogen flow is 0.4 L / min; air cooling is used in the cooling stage, the cooling rate is 5 ℃ / min, and the temperature is cooled to below 500 ℃ and then cooled in the furnace. After densification sintering, the ruthenium target material of the required size is prepared through mechanical grinding and polishing treatment.

[0039] Example 2 (1) The ruthenium powder with a purity of more than 99.95% is selected for hydrogen reduction treatment, and the holding temperature during hydrogen reduction treatment is 550 ℃, and the time is 90 min. After the end, the ruthenium powder is broken and classified by sieving, and the screen numbers are 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# screen is taken as the raw material.

[0040] (2) The ruthenium powder after step (1) is pressed into a shape by selecting a circular tablet steel mold, and the mold size is 30 mm in diameter, and the pressure is kept at 25 MPa during pressing, and the pressure holding time is 120 s.

[0041] (3) The ruthenium blank after step (2) is loaded into a package and placed in a cold isostatic pressing machine for cold isostatic pressing treatment, and the pressure is kept at 250 MPa, and the pressure holding time is 10 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density blank is prepared.

[0042] (4) The high-density ruthenium blank after step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, sintering and cooling. In the heating stage, nitrogen is passed for 60 min first, and then hydrogen is opened, and the heating rate is 10 ℃ / min; the temperature in the holding stage is 1100 ℃, the sintering time is 90 min, and the hydrogen flow is 0.4 L / min; air cooling is used in the cooling stage, the cooling rate is 5 ℃ / min, and the temperature is cooled to below 500 ℃ and then cooled in the furnace. After densification sintering, the ruthenium target material of the required size is prepared through mechanical grinding and polishing treatment.

[0043] Example 3 (1) The ruthenium powder with a purity of more than 99.95% is selected for hydrogen reduction treatment, and the holding temperature during hydrogen reduction treatment is 650 ℃, and the time is 60 min. After the end, the ruthenium powder is broken and classified by sieving, and the screen numbers are 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# screen is taken as the raw material.

[0044] (2) The ruthenium powder after step (1) is pressed into a shape by selecting a circular tablet steel mold, the mold size is 45 mm in diameter, the pressure is kept at 30 MPa during pressing, and the pressure holding time is 300 s.

[0045] (3) The ruthenium blank after step (2) is placed in a package and put into a cold isostatic pressing machine for cold isostatic pressing treatment, the pressure is kept at 300 MPa, and the pressure holding time is 5 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density blank is prepared.

[0046] (4) The high-density ruthenium blank after step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, holding and cooling. In the heating stage, first pass through the inert gas nitrogen for 60 min, then open the hydrogen, the heating rate is 10 ℃ / min; the holding temperature is 1200 ℃, the sintering time is 70 min, and the hydrogen flow is 0.4 L / min; in the cooling stage, air cooling is adopted, the cooling rate is 5 ℃ / min, and the temperature is cooled to below 500 ℃ and cooled with the furnace. After densification sintering, the ruthenium target material of the required size is prepared after mechanical grinding and polishing treatment.

[0047] Example 4 (1) The ruthenium powder with a purity of more than 99.95% is subjected to hydrogen reduction treatment, the holding temperature during hydrogen reduction treatment is 450 ℃, and the time is 60 min. After the end, the ruthenium powder is broken and classified by sieving, the screen numbers are 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# screen is taken as the raw material.

[0048] (2) The ruthenium powder after step (1) is pressed into a shape by selecting a circular tablet steel mold, the mold size is 45 mm in diameter, the pressure is kept at 20 MPa during pressing, and the pressure holding time is 300 s.

[0049] (3) The ruthenium blank after step (2) is placed in a package and put into a cold isostatic pressing machine for cold isostatic pressing treatment, the pressure is kept at 200 MPa, and the pressure holding time is 10 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density blank is prepared.

[0050] (4) The high-density ruthenium blank after step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, holding and cooling. In the heating stage, first pass through the inert gas nitrogen for 60 min, then open the hydrogen, the heating rate is 10 ℃ / min; the holding temperature is 1300 ℃, the sintering time is 80 min, and the hydrogen flow is 0.4 L / min; in the cooling stage, air cooling is adopted, the cooling rate is 5 ℃ / min, and the temperature is cooled to below 500 ℃ and cooled with the furnace. After densification sintering, the ruthenium target material of the required size is prepared after mechanical grinding and polishing treatment.

[0051] Example 5 (1) Selecting the ruthenium powder with purity of 99.95% or above for hydrogen reduction treatment, the holding temperature is 650℃, and the time is 60 min. After the end, the agglomerated ruthenium powder is broken and classified by sieves, the mesh numbers are 100#, 120#, 150#, 200#, 300# and 500# in turn, and the ruthenium powder under the 500# sieve is taken as the raw material.

[0052] (2) The ruthenium powder treated in step (1) is pressed into shape by using a circular tablet pressing steel mold, the mold size is 20 mm in diameter, the pressure is kept at 20 MPa during pressing, and the pressure holding time is 300 s.

[0053] (3) The ruthenium blank treated in step (2) is loaded into a package and placed in a cold isostatic pressing machine for cold isostatic pressing treatment, the pressure is kept at 250 MPa, and the pressure holding time is 5 min. After the cold isostatic pressing treatment, the package and the mold are removed, and a high-density blank is prepared.

[0054] (4) The high-density ruthenium blank treated in step (3) is placed in an atmosphere sintering furnace for sintering treatment, including three stages of heating, holding and cooling. In the heating stage, first pass the inert gas nitrogen for 60 min, then open the hydrogen, and the heating rate is 10℃ / min; in the holding stage, the temperature is 1000℃, the sintering time is 90 min, and the hydrogen flow is 0.4 L / min; in the cooling stage, air cooling is adopted, the cooling rate is 5 ℃ / min, and the temperature is cooled to below 500℃ and then cooled with the furnace. After densification sintering, the ruthenium target material with the required size is prepared through mechanical polishing treatment.

[0055] The oxygen content, average grain size, and crystal face preferred orientation of the ruthenium target materials prepared in each example and the comparative example are tested, and the results are shown in Table 1.

[0056] Table 1: Differences in structure, magnetic permeability and sputtering performance of ruthenium target materials of different examples and comparative examples

[0057] From the data in Table 1, it can be seen that: the hydrogen reduction treatment of the raw material ruthenium powder combined with the double oxygen removal strategy of hydrogen atmosphere sintering is the key factor to reduce the internal oxygen content of the ruthenium target material. Specifically, the oxygen content of the ruthenium target materials prepared in Examples 1-5 is controlled within the range of 20 ppm, while the oxygen content of Comparative Example 1 which does not adopt the double oxygen removal is as high as 110 ppm, significantly exceeding the low oxygen design requirement, which confirms the effectiveness of the double oxygen removal step in inhibiting the oxidation of the ruthenium target material. In addition, the process parameters of the steps of mold pressing, cold isostatic pressing and sintering can be synergistically controlled, which can directly affect the microstructure and sputtering performance of the ruthenium target material.

[0058] In summary, by controlling the preparation process of the ruthenium target material (oxygen removal step, forming and sintering parameters), the specific crystallographic orientation, oxygen content and grain size of the target material can be precisely controlled. The ruthenium target material prepared in the embodiment has better micro oxygen content, grain uniformity, controllability of crystal face orientation and sputtering performance than the comparative examples and the prior art, and has significant technical advantages and application value.

[0059] The above only describes the preferred embodiments of the present application. It should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1. A method for preparing a ruthenium sputtering target, characterized in that, Includes the following steps: Ruthenium powder was subjected to hydrogen reduction treatment, crushing and sieving in sequence to obtain reduced ruthenium powder; The reduced ruthenium powder is sequentially subjected to pressing, cold isostatic pressing, and sintering to obtain the ruthenium sputtering target. The cold isostatic pressing is performed at a pressure of 200-300 MPa for a holding time of ≥5 min. The sintering is carried out under hydrogen conditions. The sintering includes a heating stage, a holding stage, and a cooling stage. The heating rate during the heating stage is ≤10℃ / min. The holding temperature during the holding stage is 1000-1300℃ for a holding time of 60-90 min.

2. The preparation method according to claim 1, characterized in that, The holding temperature for the hydrogen reduction treatment is 450~650℃, and the time is 60~120 min; before introducing hydrogen, nitrogen or an inert gas is introduced first.

3. The preparation method according to claim 1, characterized in that, The sieving is a graded sieving, and the sieves used for the graded sieving have sieve numbers of 100#, 120#, 150#, 200#, 300#, and 500# in sequence.

4. The preparation method according to claim 1, characterized in that, The pressing pressure is 20~30 MPa, and the holding time is 120~300 s.

5. The preparation method according to claim 1 or 4, characterized in that, The mold used for pressing is a circular mold with a diameter of 20~45 mm; the mold is made of tool steel and the hardness of the circular mold used for pressing is HRC≥65.

6. The preparation method according to claim 1, characterized in that, The cold isostatic pressing process uses a plastic or rubber sheath with elasticity and plasticity.

7. The preparation method according to claim 1, characterized in that, Before introducing hydrogen during the heating stage, an inert gas or nitrogen is introduced first; during the heat preservation stage, the hydrogen flow rate is ≤0.4 L / min; during the cooling stage, the temperature is first cooled to below 500℃ by air cooling, and then cooled with the furnace; the cooling rate of the air cooling is ≤5℃ / min.

8. The preparation method according to claim 1, characterized in that, The sintering process further includes mechanical polishing of the resulting ruthenium sputtering target.

9. The preparation method according to claim 1, characterized in that, The ruthenium sputtering target has a purity of ≥99.95%, an oxygen content of ≤20ppm, an average grain size of ≤2μm, and a target density of ≥99%.

10. The preparation method according to claim 1 or 9, characterized in that, The preferred orientation of the sputtering surface of the ruthenium sputtering target tends to be in the {10-11} or {0002} direction.

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