A lanthanum nickelate ceramic target and a method for producing the same

Abstract

The application discloses a lanthanum nickelate ceramic target material and a preparation method thereof, relates to the technical field of the lanthanum nickelate ceramic target material, and comprises the following steps: mixing Ni2O3 powder and La2O3 powder by a wet method, and then performing pre-synthesis to obtain LiNiO X The ceramic powder is pre-pressed in a vacuum hot-pressing sintering furnace after being loaded into a mold, and then is subjected to hot-pressing vacuum sintering; the lanthanum nickelate ceramic powder after solid-phase synthesis is directly subjected to hot-pressing sintering at low temperature and high pressure, pressure compensation is performed during the heat preservation stage of 600-800 DEG C in the sintering stage, and the occurrence of radial shrinkage is avoided; after reaching the sintering temperature, the uniform temperature field is adopted, and a lower pressing speed is adopted to effectively avoid the cracking of the target material, so that the crystal grain organization is uniform and small; and finally, the lanthanum nickelate ceramic powder has a relatively smooth flatness, high density and excellent sputtering performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lanthanum nickelate ceramic target material, and particularly relates to a lanthanum nickelate ceramic target material and a preparation method thereof. BACKGROUND

[0002] Generally, the material used as the bottom electrode of the ferroelectric thin film device is mainly the noble metal platinum (Pt), which has good conductivity, but the preparation cost is extremely high, and the adhesion and fatigue resistance of the ferroelectric thin film on the platinum are insufficient. The metal oxide lanthanum nickelate (LaNiO3) with a perovskite structure has good conductivity and low cost, and is an excellent material for the bottom electrode of the ferroelectric thin film. Since the target material has a great influence on the performance of the sputtered thin film, the higher the purity of the ceramic target material is, the better the uniformity of the sputtered thin film and the consistency of the quality of the batch products are, so the prerequisite for preparing a high-quality lanthanum nickelate thin film is to prepare a high-quality lanthanum nickelate ceramic target material.

[0003] In the prior art, the technology for preparing the lanthanum nickelate ceramic target material is relatively single. For example, a patent document with the publication number CN103664170A discloses a preparation technology for a lanthanum nickelate ceramic target material. The lanthanum nickelate ceramic powder is synthesized in advance through a solid-phase reaction, and then a green body is obtained through pressing at room temperature. The lanthanum nickelate target material is obtained after the green body is subjected to pressureless sintering. However, the preparation process of this method is relatively complex, there are many uncontrollable factors, and other impurities are easily introduced, so the quality of the prepared lanthanum nickelate ceramic target material cannot be guaranteed. SUMMARY

[0004] The present application aims to provide a lanthanum nickelate ceramic target material and a preparation method thereof, and solve the following technical problems:

[0005] How to improve the quality of the lanthanum nickelate ceramic target material.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] In a first aspect, the present application discloses a lanthanum nickelate ceramic target material, characterized in that the raw material components include Ni2O3 powder and La2O3 powder with a mass ratio of 2:(3-8), and the density of the lanthanum nickelate ceramic target material is ≥4 g / cm 3 .

[0008] In a further aspect of the present application, the purity of the Ni2O3 powder and the La2O3 powder is both >99.999%.

[0009] In a further aspect of the present application, the average median diameter of the Ni2O3 powder is 10-15 um, and the average median diameter of the La2O3 powder is 20-25 um.

[0010] Preferably, the average median diameter of the Ni2O3 powder is 10 um.

[0011] Preferably, the average median diameter of the La2O3 powder is 20 um.

[0012] In a second aspect, the present application also discloses a preparation method of the lanthanum nickelate ceramic target as described above, comprising the following steps:

[0013] S1, wet mixing powder

[0014] The Ni2O3 powder and the La2O3 powder are weighed and mixed by wet grinding to obtain mixed powder.

[0015] S2, LaNiO X Ceramic powder synthesis

[0016] The mixed powder is placed in a synthesis furnace for pre-synthesis, oxygen is introduced at 400-600 DEG C, the synthesis temperature is 800-1000 DEG C, the holding time is 5-10 h, and LaNiO X ceramic powder is obtained after synthesis.

[0017] Preferably, the temperature for introducing oxygen is 500 DEG C.

[0018] Preferably, the synthesis temperature is 900 DEG C, and the holding time is 8 h.

[0019] S3, mold loading

[0020] The graphite paper is cut according to the size of the mold, and the graphite paper is placed at the bottom and the inner side of the mold, and then the LaNiO X ceramic powder is laid flat in the mold.

[0021] S4, pre-pressing

[0022] The graphite mold loaded with the mixed powder is placed in a vacuum hot-pressing sintering furnace, and the pressure is increased to 6-10 MPa, and then the pressure is released to zero after holding for 10-15 min;

[0023] Preferably, the pressure is increased to 8 MPa, and the holding time is 12 h.

[0024] S5, hot-pressing sintering

[0025] After vacuumizing to below 5 Pa, the temperature is increased at a rate of 8-10 DEG C / min to 600-800 DEG C, and then the temperature increasing rate is adjusted to 5-8 DEG C / min and the temperature is increased to 900-1100 DEG C, and the holding time is 30-60 min; after the holding time ends, the pressure is increased at a rate of 0.1-0.3 MPa / min to 20-25 MPa, and the holding time is 90-150 min, and finally the furnace is cooled to 100-200 DEG C, and the LaNiO X ceramic target blank is obtained after the end.

[0026] S6, machining

[0027] LaNiO X The graphite paper on the ceramic target blank is ground, CNC processed and machined to a target material with qualified size according to the drawing requirements, and relevant defect and density tests are performed, and after no abnormality, vacuum packaging is performed.

[0028] Preferably, the temperature is raised to 700℃ at a temperature raising rate of 9℃ / min, then the temperature raising rate is adjusted to 7℃ / min and the temperature is raised to 1000℃, and the temperature is kept for 45min;

[0029] Preferably, after the temperature keeping is finished, the pressure is increased to 23MPa at a pressure increasing rate of 0.2MPa / min, the temperature is kept and the pressure is kept for 120min, and finally the temperature is decreased to 150℃ along with the furnace,

[0030] In a further scheme of the present application, in step S1, the wet mixing and grinding method comprises the following steps:

[0031] The weighed Ni2O3 powder and La2O3 powder are poured into a polyurethane powder mixing barrel, powder mixing balls are added, anhydrous ethanol is added, and then a drum-type ball mill is used to mix at a rotating speed of 300-400r / min for 20-32h;

[0032] Preferably, the drum-type ball mill is used to mix at a rotating speed of 350r / min for 25h

[0033] In a further scheme of the present application, the powder mixing balls are added according to a ball-to-material ratio of 1:2.

[0034] In a further scheme of the present application, the powder mixing balls are one of polyurethane grinding balls, agate grinding balls or zirconium oxide grinding balls.

[0035] In a further scheme of the present application, the anhydrous ethanol is added in an amount of 20%-30% of the total weight of the Ni2O3 powder and the La2O3 powder;

[0036] Preferably, the anhydrous ethanol is added in an amount of 25% of the total weight of the Ni2O3 powder and the La2O3 powder

[0037] In a further scheme of the present application, in step S3, the mold is a high-purity graphite mold.

[0038] In a further scheme of the present application, in step S4, the pressure is increased to 6-10MPa at a pressure increasing rate of 0.1-0.3MPa / min;

[0039] Preferably, the pressure is increased to 8MPa at a pressure increasing rate of 0.2MPa / min.

[0040] The present application has the following beneficial effects:

[0041] The lanthanum nickelate ceramic target material of the present application is obtained by directly hot-press sintering the lanthanum nickelate ceramic powder after solid-phase synthesis at low temperature and high pressure, and the pressure is supplemented during the holding stage at 600-800℃ in the sintering stage to avoid the occurrence of radial shrinkage; after reaching the sintering temperature, the uniform temperature field is adopted at the same time, and a lower pressing rate is adopted to effectively avoid the cracking of the target material, so that the grain structure is uniform and small, and the finally obtained lanthanum nickelate ceramic powder is quite flat, has high density, and excellent sputtering performance. BRIEF DESCRIPTION OF DRAWINGS

[0042] The present application will be further described below in conjunction with the accompanying drawings.

[0043] Figure 1 It is a flow chart of the preparation method of the lanthanum nickelate ceramic target material of the present application. DETAILED DESCRIPTION

[0044] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of 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 other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0045] In the following examples, the experimental methods are conventional methods, and are carried out according to the techniques or conditions described in the literature in the art or according to the product instructions, unless otherwise specified. The materials, reagents, etc. used in the following examples can be obtained from commercial channels, unless otherwise specified. Example 1

[0046] 100g of Ni2O3 powder (purity > 99.999%, average median diameter 10um) and 400g of La2O3 powder (purity > 99.999%, average median diameter 20um) were weighed and added together into a 10L polyurethane powder mixing barrel, 250g of zirconium oxide grinding balls were added, 100g of anhydrous ethanol was added, a drum-type ball mill was set at a rotating speed of 300r / min, and the mixing was carried out at this rotating speed for 32h to obtain a mixed powder; the mixed powder was placed in a synthesis furnace, oxygen was introduced at 400℃, then the temperature was raised to 800℃ and kept for 10h, and after the end, LaNiO x Ceramic powder; high-purity graphite molds were selected and graphite paper was cut according to the size, the graphite paper was placed at the bottom and the inner side of the mold, then LaNiO XThe ceramic powder is laid flat in a graphite mold; the graphite mold containing the mixed powder is placed in a vacuum hot-pressing sintering furnace, and the pressure is increased to 6 MPa at a rate of 0.1 MPa / min, then the pressure is kept constant for 15 min, then the pressure is released to zero, then vacuum is drawn to below 3 Pa, then the temperature is increased to 600 ℃ at a rate of 8 ℃ / min, then the temperature increasing rate is adjusted to 5 ℃ / min and the temperature is increased to 900 ℃, and the temperature is kept constant for 60 min; after the temperature keeping is completed, the pressure is increased to 20 MPa at a rate of 0.1 MPa / min, and the temperature is kept constant and the pressure is kept constant for 150 min, and finally the furnace is cooled to 100 ℃, and LaNiO X A ceramic target blank. Example 2

[0047] 100 g of Ni2O3 powder (purity > 99.999%, average median diameter 10 um) and 250 g of La2O3 powder (purity > 99.999%, average median diameter 20 um) are weighed into a 10 L polyurethane powder mixing barrel, 175 g of zirconium oxide grinding balls are added, 87.5 g of anhydrous ethanol is added, a drum-type ball mill is set to a rotation speed of 350 r / min, and the mixture is mixed at this rotation speed for 25 h to obtain a mixed powder; the mixed powder is placed in a synthesis furnace, oxygen is introduced at 500 ℃, then the temperature is increased to 900 ℃ and kept constant for 8 h, and LaNiO x Ceramic powder; high-purity graphite molds are selected and graphite paper is cut according to the size of the molds, the graphite paper is placed at the bottom and the inner side of the molds, then LaNiO X The ceramic powder is laid flat in a graphite mold; the graphite mold containing the mixed powder is placed in a vacuum hot-pressing sintering furnace, and the pressure is increased to 8 MPa at a rate of 0.2 MPa / min, then the pressure is kept constant for 12 min, then the pressure is released to zero, then vacuum is drawn to 5 Pa, then the temperature is increased to 700 ℃ at a rate of 9 ℃ / min, then the temperature increasing rate is adjusted to 7 ℃ / min and the temperature is increased to 1000 ℃, and the temperature is kept constant for 45 min; after the temperature keeping is completed, the pressure is increased to 23 MPa at a rate of 0.2 MPa / min, and the temperature is kept constant and the pressure is kept constant for 120 min, and finally the furnace is cooled to 150 ℃, and LaNiO X A ceramic target blank. Example 3

[0048] Take 100 g of Ni2O3 powder (purity > 99.999%, average median diameter 10 um), 150 g of La2O3 powder (purity > 99.999%, average median diameter 20 um) together into a 10 L polyurethane powder mixing barrel, add 125 g of zirconium oxide grinding balls, then add 75 g of anhydrous ethanol, and set the rotating speed of the drum-type ball mill to 400 r / min. Mix for 20 h at this rotating speed to obtain a mixed powder. Place the mixed powder in a synthesis furnace, pass oxygen at 600 ℃, then heat to 1000 ℃ and keep for 5 h, and after the end, obtain LaNiO x ceramic powder; select a high-purity graphite mold and cut graphite paper according to its size, place the graphite paper at the bottom and inner side of the mold, then place the mixed powder in the graphite mold, and place the graphite mold in a vacuum hot-pressing sintering furnace, and pressurize to 10 MPa at a pressurizing rate of 0.3 MPa / min, then keep the pressure for 10 min, then release the pressure to zero, then vacuumize to 4 Pa, then start heating at a heating rate of 10 ℃ / min to 800 ℃, then adjust the heating rate to 8 ℃ / min and heat to 1100 ℃, keep for 30 min, then pressurize to 25 MPa at a pressurizing rate of 0.3 MPa / min, keep for 90 min, and finally cool to 200 ℃ with the furnace, and after the end, obtain LaNiO X ceramic powder; select a high-purity graphite mold and cut graphite paper according to its size, place the graphite paper at the bottom and inner side of the mold, then place the mixed powder in the graphite mold, and place the graphite mold in a vacuum hot-pressing sintering furnace, and pressurize to 10 MPa at a pressurizing rate of 0.3 MPa / min, then keep the pressure for 10 min, then release the pressure to zero, then vacuumize to 4 Pa, then start heating at a heating rate of 10 ℃ / min to 800 ℃, then adjust the heating rate to 8 ℃ / min and heat to 1100 ℃, keep for 30 min, then pressurize to 25 MPa at a pressurizing rate of 0.3 MPa / min, keep for 90 min, and finally cool to 200 ℃ with the furnace, and after the end, obtain LaNiO X ceramic target blank.

[0049] Comparative Example 1

[0050] Take 100 g of Ni2O3 powder (purity > 99.999%, average median diameter 10 um), 150 g of La2O3 powder (purity > 99.999%, average median diameter 20 um) together into a 10 L polyurethane powder mixing barrel, add 125 g of zirconium oxide grinding balls, then add 75 g of anhydrous ethanol, and set the rotating speed of the drum-type ball mill to 400 r / min. Mix for 20 h at this rotating speed to obtain a mixed powder. Place the mixed powder in a synthesis furnace, pass oxygen at 600 ℃, then heat to 1000 ℃ and keep for 5 h, and after the end, obtain LaNiO x ceramic powder; select a high-purity graphite mold and cut graphite paper according to its size, place the graphite paper at the bottom and inner side of the mold, then place the mixed powder in the graphite mold, and place the graphite mold in a vacuum hot-pressing sintering furnace, and pressurize to 10 MPa at a pressurizing rate of 0.3 MPa / min, then keep the pressure for 10 min, then release the pressure to zero, then vacuumize to 4 Pa, then start heating at a heating rate of 10 ℃ / min to 800 ℃, then adjust the heating rate to 8 ℃ / min and heat to 1100 ℃, keep for 30 min, then pressurize to 25 MPa at a pressurizing rate of 0.3 MPa / min, keep for 90 min, and finally cool to 200 ℃ with the furnace, and after the end, obtain LaNiO X ceramic powder; select a high-purity graphite mold and cut graphite paper according to its size, place the graphite paper at the bottom and inner side of the mold, then place the mixed powder in the graphite mold, and place the graphite mold in a vacuum hot-pressing sintering furnace, and pressurize to 10 MPa at a pressurizing rate of 0.3 MPa / min, then keep the pressure for 10 min, then release the pressure to zero, then vacuumize to 4 Pa, then start heating at a heating rate of 10 ℃ / min to 800 ℃, then adjust the heating rate to 8 ℃ / min and heat to 1100 ℃, keep for 30 min, then pressurize to 25 MPa at a pressurizing rate of 0.3 MPa / min, keep for 90 min, and finally cool to 200 ℃ with the furnace, and after the end, obtain LaNiOX Ceramic target blank.

[0051] Comparative Example 2

[0052] Compared with Example 2, the only difference is that "vacuuming to 5 Pa and then starting heating" is changed to "vacuuming to 6 Pa and then starting heating," while other conditions remain the same, ultimately yielding LaNiO. X Ceramic target blank.

[0053] LaNiO prepared in Examples 1-3 and Comparative Examples 1-2 X The ceramic target material is subjected to performance testing, including grain distribution uniformity and density testing. To facilitate the testing, LaNiO is used. X The ceramic target blank is machined into a square shape with a length, width and height of 3cm by grinding and CNC machining. The specific testing method is as follows.

[0054] Grain distribution uniformity testing: A digital multimeter was used as the resistance sensing element in LaNiO. X Several transverse and longitudinal detection points are set in the middle of the ceramic target. The test probes of the resistance testing instrument are connected to LaNiO respectively. X A closed circuit is formed at each detection point of the ceramic target material. The resistance value of each detection point is measured and recorded in sequence. The smaller the difference in resistance value, the higher the uniformity of the grain distribution of the target material, and vice versa. The data difference is reflected by calculating the variance of the resistance corresponding to the transverse detection points and the longitudinal detection points respectively.

[0055] Density detection: The density of the target material is calculated by weighing.

[0056] The test results are listed in Table 1, as follows:

[0057]

[0058] Analysis of the data in Table 1 shows that the LaNiO prepared in Examples 1-3... X The ceramic target material compared to the LaNiO prepared in Comparative Examples 1-2 X For ceramics, the uniformity of grain distribution and density are significantly higher, indicating that the LaNiO of this invention... X Ceramic targets are of higher quality.

[0059] The foregoing has provided a detailed description of one embodiment of the present invention, but this description is merely a preferred embodiment and should not be construed as limiting the scope of the invention. All equivalent variations and modifications made within the scope of the claims of this invention should still fall within the patent coverage of this invention.

Claims

1. A method for preparing a lanthanum nickelate ceramic target, characterized in that, Includes the following steps: S1, Wet mixing Weigh out Ni2O3 powder and La2O3 powder in a mass ratio of 2:(3-8), and mix and grind them by wet method to obtain mixed powder; S2: LaNiO X Ceramic powder synthesis The mixed powder is put into a synthesis furnace, pre-synthesized, oxygen is passed in at 400-600°C, the synthesis temperature is 800-1000°C, the holding time is 5-10h, and after the synthesis is finished, LaNiO X ceramic powder; S3: Molding The graphite paper is cut according to the size of the mold, and the graphite paper is placed at the bottom and inner side of the mold, and then LaNiO X The ceramic powder is laid flat in the mold. S4: Pre-compression The graphite mold containing the mixed powder is placed in a vacuum hot pressing sintering furnace and pressurized to 6-10 MPa. After holding the pressure for 10-15 minutes, the pressure is released until it is zero. S5: Hot pressing and sintering After evacuating to below 5 Pa, begin heating at a rate of 8-10 °C / min to 600-800 °C. Then adjust the heating rate to 5-8 °C / min and heat to 900-1100 °C, holding for 30-60 min. After holding, pressurize to 20-25 MPa at a rate of 0.1-0.3 MPa / min, holding for 90-150 min. Finally, cool down with the furnace to 100-200 °C. The resulting product is LaNiO. X Ceramic target blank; S6: Machining Removal of LaNiO X The graphite paper on the ceramic target blank is ground and CNC machined according to the drawing requirements until the target material meets the dimensional requirements. After relevant defect and density tests are performed and no abnormalities are found, it is vacuum-packed to obtain LaNiO. X Ceramic target material.

2. The method for preparing the lanthanum nickelate ceramic target according to claim 1, characterized in that, In step S1, the wet mixing and grinding method includes the following steps: The weighed Ni2O3 powder and La2O3 powder were poured into a polyurethane mixing tank, a mixing ball was added, and then anhydrous ethanol was added. The mixture was then mixed for 20-32 hours using a drum ball mill at a speed of 300-400 r / min.

3. The method for preparing the lanthanum nickelate ceramic target according to claim 2, characterized in that, The mixed powder balls are added at a ball-to-material ratio of 1:

2.

4. The method for preparing the lanthanum nickelate ceramic target according to claim 2, characterized in that, The powder mixing ball is one of polyurethane grinding balls, agate grinding balls, or zirconia grinding balls.

5. The method for preparing the lanthanum nickelate ceramic target according to claim 2, characterized in that, The amount of anhydrous ethanol added is 20%-30% of the sum of the weights of Ni2O3 powder and La2O3 powder.

6. The method for preparing the lanthanum nickelate ceramic target according to claim 1, characterized in that, In step S3, the mold is a high-purity graphite mold.

7. The method for preparing the lanthanum nickelate ceramic target according to claim 1, characterized in that, In step S4, the pressure is increased to 6-10 MPa at a rate of 0.1-0.3 MPa / min.

8. The method for preparing lanthanum nickelate ceramic target according to claim 1, characterized in that, In step S1, the purity of both Ni2O3 powder and La2O3 powder is >99.999%.

9. The method for preparing the lanthanum nickelate ceramic target according to claim 1, characterized in that, In step S1, the average median diameter of the Ni2O3 powder is 10-15 μm, and the average median diameter of the La2O3 powder is 20-25 μm.

10. A lanthanum nickelate ceramic target, characterized in that, It is prepared by the method for preparing lanthanum nickelate ceramic target according to any one of claims 1-7.

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