A magnesium oxide partially stabilized zirconia slurry, its preparation method and use

Abstract

The application discloses a kind of magnesium oxide partial stable zirconium oxide slurry and its preparation method and application, take zirconium oxychloride crystal and dissolve in deionized water, add magnesium chloride hexahydrate to form chloride mixed solution;Excess ammonia is added dropwise to the mixed solution, and after zirconium hydroxide, magnesium hydroxide is precipitated, centrifugal and repeatedly hot water washing;Drying and high-temperature calcination, then add dispersing agent and wet grinding solvent ball milling;After drying, the qualified powder is prepared into aqueous solution, and a dispersing agent is ultrasonically vibrated;pH is adjusted with ammonia water, and the slurry is obtained by continuous stirring.The application process is simple, and operability is relatively strong, sample fluidity and dispersibility are better, can effectively inhibit the stress concentration caused by abrasive particle accumulation during grinding of GaSb substrate, and the surface quality of GaSb substrate after grinding is greatly improved, and the damage rate of T2SL infrared detector chip GaSb substrate after grinding is low.

Description

Technical Field

[0001] This application relates to the field of semiconductor material preparation technology, and more specifically, to a magnesium oxide partially stabilized zirconium oxide slurry, its preparation method, and its application. Background Technology

[0002] Antimonide type II superlattices (T2SL) possess advantages such as tunable band structure, wide wavelength coverage, high detectivity, and good large-area uniformity due to their type II band structure, making them an ideal material for third-generation infrared detectors after HgCdTe and QWIP materials. However, as a back-attribution device, the infrared transmittance of T2SL infrared detectors is low under cooling conditions due to GaSb single-crystal substrates only a few hundred micrometers thick. Furthermore, during low-temperature cycling tests, differences in the thermal expansion coefficients of the materials can lead to cracking and fragmentation of the GaSb substrate, affecting material consistency and degrading device performance. Therefore, the fabrication of ultrathin, high-quality GaSb substrates is crucial.

[0003] The surface quality indicators of GaSb substrates after grinding and polishing mainly include damage and defects, surface roughness, surface particles and residues, etc. Among them, damage (including cracks, fragmentation, etc.) can greatly affect the consistency of chip materials, leading to a significant decrease in device performance. It is worth noting that simple mechanical grinding, as one of the effective means of removing large amounts of GaSb substrates, involves high frictional forces on the GaSb substrate and a fast average removal rate (MRR), making it the main process affecting the surface quality of GaSb substrates.

[0004] Currently, the main products used for GaSb substrate grinding and removal in the domestic and international markets are alumina aqueous solution abrasives. The alumina particles are typically smelted at high temperatures in an electric arc furnace, then processed, finely crushed, and hydraulically classified into corundum micropowders of different particle sizes. Finally, these are prepared into a single aqueous solution abrasive according to a specific abrasive particle volume ratio. This process is simple overall, relatively inexpensive, and produces abrasive particles with high hardness and density, resulting in excellent average removal rates of GaSb substrates. However, the abrasives prepared by this method suffer from poor slurry stability, flowability, and dispersibility. During the grinding process, alumina particles tend to agglomerate and sink to the grinding pad, significantly increasing the probability of stress concentration on the GaSb substrate, leading to edge and corner breakage and cracks. These problems are fatal for chips worth tens of thousands of dollars.

[0005] Zirconia, as a novel abrasive, possesses high hardness and density, as well as good toughness and wear resistance. The preparation methods for zirconia powder include electrofusion and chemical methods. Chemical methods are further divided into hydrolysis precipitation, hydrothermal methods, sol-gel methods, and co-precipitation methods. The first three methods suffer from complex processes, high energy consumption, harsh reaction conditions, and environmental pollution. In contrast, the co-precipitation method is simple and readily yields high-purity micro-nano-scale powders, thus attracting the attention of most domestic zirconia manufacturers. Chinese patent application (application number CN201310300328.0) discloses a "low-temperature synthesis method for non-agglomerated, fully stable cubic phase nano-zirconia powder," the production process of which is as follows: First, a stabilizer and zirconium salt are dissolved separately in concentrated nitric acid and deionized water to form stable transparent solutions. The two solutions are then mixed in a certain proportion, and the pH of the mixed solution is adjusted with ammonia water. Subsequently, an excess of precipitant is added to obtain a precursor, which is then dried and ground for later use. Next, it is mixed with molten salt, dried, and calcined. Finally, after washing with deionized water and drying, stable cubic phase nano-zirconia powder is obtained. This method requires high precision in powder particle size and shape, and involves low calcination temperatures. The entire process is insufficient to produce powders with larger particle sizes, which is detrimental to ensuring a high average removal rate of GaSb substrates and reduces production efficiency. Furthermore, the use of concentrated nitric acid to dissolve zirconium salts causes environmental pollution and is detrimental to sustainable development. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a method for preparing a magnesium oxide partially stabilized zirconia slurry. This method has good repeatability and strong operability. The GaSb substrate after grinding with the slurry prepared by this invention has a low damage rate, making it suitable for the advanced production requirements of T2SL infrared detector chips. Specifically, the method for preparing the magnesium oxide partially stabilized zirconia slurry of this invention includes the following steps:

[0007] (1) Weigh zirconium oxychloride (ZrOCl2·8H2O) crystals and dissolve them in deionized water to prepare a saturated solution. After filtering to remove insoluble substances and other impurities, add magnesium chloride hexahydrate (MgCl2·6H2O) at a mass fraction of 1% to 10% of zirconium oxychloride and stir evenly to form a chloride mixed solution. In this invention, magnesium is added as a stabilizer for zirconium oxide particles.

[0008] (2) Add excess ammonia water (NH3·H2O) to the chloride mixed solution described in step (1), stir magnetically for 3 to 6 hours, and let stand for 6 to 24 hours to allow zirconium hydroxide and magnesium hydroxide to precipitate completely; then, centrifuge at 5000 to 10000 rpm for 5 to 15 minutes, wash the precipitate repeatedly with hot water, and repeat the centrifugation operation once more.

[0009] (3) Heat and dry at 60-120℃ for 3-12 hours, then calcine at 1500-1800℃ to obtain magnesium oxide partially stabilized zirconium oxide powder; after complete cooling, put the magnesium oxide partially stabilized zirconium oxide powder into a ball mill, add 0.01-0.15wt.% polyacrylic acid dispersant and wet milling solvent, and wet mill for 8-24 hours;

[0010] (4) Take out the ball-milled magnesium oxide partially stabilized zirconium oxide powder from the ball mill and dry it completely at 80-150℃. Screen out the powder with a size of 1-5μm, add deionized water so that the powder accounts for 8%-20% of the volume fraction of the mixed solution, stir evenly, and then add 0.05-3.00wt.% of dispersant and ultrasonically vibrate for 30-90min.

[0011] (5) Adjust the pH of the mixed solution to 8-10 with ammonia water and continue mechanical stirring for 6-12 hours to obtain the magnesium oxide partially stabilized zirconium oxide slurry.

[0012] Furthermore, the method also includes one or more of the following (1)-(12):

[0013] (1) In step (1), zirconium oxychloride crystals with a mass percentage of 99.5% to 99.9% are selected;

[0014] (2) In step (1), rapid filter paper with a pore size of 80-120 μm is used to filter out insoluble substances and other impurities;

[0015] (3) The temperature of the hot water in step (2) is 60-70℃;

[0016] (4) In step (2), the filter paper with a pore size of 1 to 3 μm is repeatedly washed with hot water 7 to 15 times;

[0017] (5) The wet grinding solvent in step (3) is anhydrous ethanol or high-purity water;

[0018] (6) The ball mill in step (3) is an ultrafine ball mill;

[0019] (7) In step (3), calcination is carried out in a resistance furnace;

[0020] (8) The amount of wet milling solvent added is 50% of the powder mass;

[0021] (9) The dispersant in step (4) is selected from AD8098 or ethylene glycol;

[0022] (10) In step (4), a high-precision electroforming sieve is used to screen the powder;

[0023] (11) Steps (1)-(5) are performed in a clean environment of Class 1,000 or above;

[0024] (12) In step (4), the powder accounts for 8% to 12% of the volume fraction of the mixed solution, preferably 12% of the volume fraction of the mixed solution.

[0025] The present invention also provides a magnesium oxide partially stabilized zirconium oxide slurry prepared by the aforementioned preparation method.

[0026] The present invention also provides an application of the magnesium oxide partially stabilized zirconium oxide slurry obtained by the aforementioned preparation method, wherein the application is for grinding removal on GaSb substrates.

[0027] Specifically, the magnesium oxide partially stabilized zirconia slurry is mechanically stirred evenly before being used for grinding and removing GaSb substrates. The grinding and removal method includes: fixing the GaSb substrate to be treated at the bottom of the grinding carrier, adjusting the downward pressure to 150g, placing the grinding carrier on the grinding disc; using the slurry described in this invention, adjusting the slurry outflow rate to 6ml / min, and starting the disc to rotate at a uniform speed of 10rpm; after reaching the set removal value of the substrate, removing the GaSb substrate and rinsing it clean.

[0028] The beneficial effects of this invention are:

[0029] This invention prepares a highly dispersible grinding powder using wet milling of polyacrylic acid. A dispersant is added to the aqueous solution, and the pH is adjusted to 8-10, significantly improving the slurry's fluidity and dispersibility. This effectively suppresses edge and corner breakage and cracking problems caused by stress concentration due to abrasive particle accumulation during the grinding process of GaSb substrates, greatly enhancing the surface quality of the ground GaSb substrates. Furthermore, the powder produced in this invention has a high calcination temperature (>1500℃), resulting in larger crystal volumes. Through ball milling and particle size screening, micron-sized grinding particles are obtained, ensuring a high average removal rate of the GaSb substrate during the grinding process. Moreover, this invention does not use concentrated nitric acid to prepare the slurry, making it environmentally friendly and in line with sustainable development principles. It is suitable for the advanced production needs of T2SL infrared detector chips. Attached Figure Description

[0030] Figure 1 Figure 1 shows a SEM image of the magnesium oxide partially stabilized zirconia slurry of the present invention; Figure 2 shows a slurry with an abrasive volume fraction of 12% prepared in Example 1, and Figure 3 shows a slurry with an abrasive volume fraction of 12% prepared in Example 2.

[0031] Figure 2This is a schematic diagram comparing the single-drop self-leveling of the magnesium oxide partially stabilized zirconium oxide slurry with an abrasive particle volume fraction of 12% prepared in Examples 1-2 of the present invention and the traditional alumina slurry.

[0032] Figure 3 The images show the surface morphology of GaSb substrates after mechanical polishing with a 12% magnesium oxide partially stabilized zirconium oxide slurry prepared according to Examples 1-2 of this invention, under a confocal microscope at a magnification of 5x. Figures (a) to (c) correspond to Example 1, with Figure (a) showing the upper left corner of the GaSb substrate, Figure (b) showing the upper edge of the GaSb substrate, and Figure (c) showing the center of the GaSb substrate. Figures (d) to (f) correspond to Example 2, with Figure (d) showing the lower right corner of the GaSb substrate, Figure (e) showing the lower edge of the GaSb substrate, and Figure (f) showing the center of the GaSb substrate.

[0033] Figure 4 The damage rate curves and average removal rate curves of GaSb substrate surfaces after mechanical grinding of magnesium oxide partially stabilized zirconium oxide slurry and conventional alumina slurry in Examples 1-2 of this invention are shown. Detailed Implementation

[0034] The present invention will be further described and illustrated below with reference to embodiments. However, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the present invention and the embodiments, all other inventions and embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0036] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0037] Example 1: A magnesium oxide partially stabilized zirconium oxide slurry

[0038] Its preparation method is as follows:

[0039] (1) Weigh out 99.5% zirconium oxychloride (ZrOCl2·8H2O) crystals and dissolve them in deionized water to prepare a saturated solution. After filtering the sparingly soluble substances and other impurities through rapid filter paper with a pore size of 80-120μm, add 2.5wt.% analytical grade magnesium chloride hexahydrate (MgCl2·6H2O) and stir until homogeneous to form a chloride mixed solution.

[0040] (2) Add excess ammonia water (NH3·H2O) dropwise to the mixed solution, stir magnetically for 6 hours, and then let stand for 12 hours to allow zirconium hydroxide and magnesium hydroxide to precipitate completely. Then, centrifuge at 8000 rpm for 10 minutes. After centrifugation, wash the solution repeatedly 15 times with 70℃ hot water on slow-speed filter paper with a pore size of 1–3 μm. Finally, repeat the centrifugation process once more.

[0041] (3) Dry the powder in an oven at 100°C for 12 hours, and then calcine it in a resistance furnace at 1650°C to obtain magnesium oxide partially stabilized zirconium oxide (Mg-PSZ) powder. After complete cooling, put the magnesium oxide partially stabilized zirconium oxide (Mg-PSZ) powder into an ultrafine ball mill, add 0.015 wt.% polyacrylic acid (PAA) dispersant and 50 wt.% anhydrous ethanol, and wet mill for 24 hours;

[0042] (4) Remove the ball-milled Mg-PSZ from the ball mill and dry it completely at 100℃. Then, screen it using a high-precision electroforming sieve with a pore size of 5μm and a spacing of 15μm. Add the qualified powder to deionized water at a concentration of 8%, 12%, 16%, and 20% of the mixed solution volume fraction (abrasive volume fraction). Stir well and then add 1.5 wt.% of the powder weight of dispersant AD8098. Ultrasonically vibrate for 30 min.

[0043] (5) Adjust the pH of the mixed solution to 9 with ammonia water and stir mechanically for 12 hours to obtain Mg-PSZ grinding slurry. The prepared grinding slurry should be stored in a cool, ventilated, and ultra-clean environment. The storage time should not be too long, and it should be mechanically stirred evenly before use.

[0044] like Figure 1 As shown in (a), the SEM image of the magnesium oxide partially stabilized zirconia slurry from Example 1 shows that the abrasive particles in the slurry prepared in this example are amorphous powder particles. After being screened through an electroforming sieve with a pore size of 5 μm, the particle size is mostly concentrated between 1 and 5 μm, and there is no obvious agglomeration. The overall particle dispersibility is good. Figure 2 As shown in the comparison experiment of single-drop self-leveling of magnesium oxide partially stabilized zirconia slurry and traditional alumina slurry in Example 1, it can be seen that the sample prepared in this embodiment has a larger single-drop flow area and better fluidity compared with traditional alumina slurry. It also shows that its wetting angle is smaller, its wettability is better, and it exhibits better dispersibility.

[0045] Example 2: A magnesium oxide partially stabilized zirconium oxide slurry

[0046] Its preparation method is as follows:

[0047] (1) Weigh out 99.5% zirconium oxychloride (ZrOCl2·8H2O) crystals and dissolve them in deionized water to prepare a saturated solution. After filtering the sparingly soluble substances and other impurities through rapid filter paper with a pore size of 80-120μm, add 2.5wt.% analytical grade magnesium chloride hexahydrate (MgCl2·6H2O) and stir until homogeneous to form a chloride mixed solution.

[0048] (2) Add excess ammonia water (NH3·H2O) dropwise to the mixed solution, stir magnetically for 6 hours, and then let stand for 12 hours to allow zirconium hydroxide and magnesium hydroxide to precipitate completely. Then, centrifuge at 8000 rpm for 10 minutes. After centrifugation, wash the solution repeatedly 15 times with 70℃ hot water on slow-speed filter paper with a pore size of 1–3 μm. Finally, repeat the centrifugation process once more.

[0049] (3) Dry the powder in an oven at 100°C for 12 hours, and then calcine it in a resistance furnace at 1650°C to obtain magnesium oxide partially stabilized zirconium oxide (Mg-PSZ) powder. After complete cooling, put the magnesium oxide partially stabilized zirconium oxide (Mg-PSZ) powder into an ultrafine ball mill, add 0.015 wt.% polyacrylic acid (PAA) dispersant and 50 wt.% anhydrous ethanol, and wet mill for 24 hours;

[0050] (4) Remove the ball-milled Mg-PSZ from the ball mill and dry it completely at 100℃. Then, screen it using a high-precision electroforming sieve with a pore size of 3μm and a spacing of 15μm. Add the qualified powder to deionized water at a concentration of 8%, 12%, 16%, and 20% of the mixed solution volume fraction (abrasive volume fraction). Stir well and then add 1.5wt.% of the powder weight of dispersant AD8098. Ultrasonically vibrate for 30 minutes.

[0051] (5) Adjust the pH of the mixed solution to 9 with ammonia water and stir mechanically for 12 hours to obtain Mg-PSZ grinding slurry. The prepared grinding slurry should be stored in a cool, ventilated, and ultra-clean environment. The storage time should not be too long, and it should be mechanically stirred evenly before use.

[0052] like Figure 1 As shown in (b), the SEM image of the magnesium oxide partially stabilized zirconia slurry from Example 2 shows that the slurry particles prepared in this example are amorphous powder particles. After being screened through an electroforming sieve with a pore size of 3 μm, the particle size is mostly concentrated between 1 and 3 μm, with no obvious agglomeration, and the overall particle dispersibility is good. Figure 2 As shown in the comparison experiment of single-drop self-leveling of magnesium oxide partially stabilized zirconia slurry and traditional alumina slurry in Example 2, it can be seen that the sample prepared in this embodiment has a larger single-drop flow area and better fluidity compared with traditional alumina slurry. It also shows that its wetting angle is smaller, its wettability is better, and it exhibits better dispersibility.

[0053] Example 3: Verification of the application effect of the magnesium oxide partially stabilized zirconium oxide slurry prepared in this invention in the grinding and removal of GaSb substrates.

[0054] The 12% magnesium oxide partially stabilized zirconia slurry prepared in Examples 1-2 was used for grinding GaSb substrates, with conventional alumina slurry as a control. The specific grinding method is as follows: The GaSb substrate to be treated was fixed to the bottom of the grinding carrier using vacuum adsorption. After adjusting the appropriate downward pressure (150g), the grinding carrier was placed on the grinding disk. The outflow rate of the grinding slurry with different abrasive volume fractions prepared in Examples 1-2 was adjusted (6ml / min), and the disk was started to rotate counterclockwise at a uniform speed (10rpm). After the substrate removal value was reached, the GaSb substrate was removed and rinsed clean.

[0055] like Figure 3 As shown, the surface morphology of GaSb substrates after mechanical polishing with magnesium oxide partially stabilized zirconium oxide slurry with a 12% abrasive volume fraction prepared in Examples 1-2 of this invention was observed using a confocal microscope. It can be found that the surface of the GaSb substrate is uniform overall, without obvious scratches, and there is no obvious damage or destruction at the edges and corners.

[0056] like Figure 4 As shown, the surface damage rate curves and average removal rate (MRR) curves of GaSb substrates after mechanical grinding with magnesium oxide partially stabilized zirconia slurry and conventional alumina slurry indicate that the surface damage rate (the proportion of scratches, obvious edge and corner damage, and destruction) of GaSb substrates corresponding to Examples 1-2 is generally lower and better than that of conventional alumina slurry. This is because the magnesium oxide partially stabilized zirconia slurry has better dispersibility and flowability than conventional alumina slurry. Therefore, under the same abrasive particle volume fraction, less slurry aggregates on the grinding disc, resulting in reduced mechanical grinding friction, thus the MRR corresponding to Examples 1-2 of this invention is lower than that of conventional alumina slurry. Even so, the removal speed corresponding to Example 1 is still as high as 13-28 μm / min, which is quite considerable. Furthermore, due to the further reduction in abrasive particle size in Example 2, the mechanical grinding friction is further reduced, further suppressing the stress concentration problem in the GaSb substrate grinding process, thus resulting in a slight decrease in the corresponding substrate surface damage rate. It is worth noting that although the MRR decreased slightly as the abrasive particle size decreased in Example 2, it still remained at a high level, reaching 9–24 μm / min.

Claims

1. Use of a magnesium oxide partially stabilized zirconia slurry for the abrasive removal of GaSb substrates, characterized in that, The preparation method of the magnesium oxide partially stabilized zirconia slurry comprises the following steps: (1) Zirconium oxychloride crystals are weighed and dissolved in deionized water to prepare a saturated solution. After removing the insoluble substances and other impurities by filtration, 1-10% of magnesium chloride hexahydrate by mass fraction of zirconium oxychloride is added and stirred uniformly to form a chloride mixed solution; (2) Excess ammonia water is added dropwise to the chloride mixed solution in step (1), and after magnetic stirring for 3-6 hours, the solution is left to stand for 6-24 hours to completely precipitate zirconium hydroxide and magnesium hydroxide. Then, centrifugation is performed at a speed of 5000-10000 rpm for 5-15 minutes, and the precipitate is repeatedly washed with hot water and then subjected to centrifugation again; (3) The mixture is heated and dried at 60-120℃ for 3-12 hours, and then calcined at 1500-1800℃ to obtain magnesium oxide partially stabilized zirconia powder. After complete cooling, the magnesium oxide partially stabilized zirconia powder is placed in a ball mill, 0.01-0.15 wt.% of polyacrylic acid dispersant and wet milling solvent are added, and wet milling is performed for 8-24 hours; (4) The ball-milled magnesium oxide partially stabilized zirconia powder is taken out from the ball mill, dried completely at 80-150℃, and sieved to obtain powder with a size of 1-5 μm. Deionized water is added to make the powder account for 8-20% of the volume fraction of the mixed solution, and then 0.05-3.00 wt.% of dispersant is added. After uniform stirring, ultrasonic oscillation is performed for 30-90 minutes, and the powder accounts for 12% of the volume fraction of the mixed solution; (5) The pH of the mixed solution is adjusted to 8-10 with ammonia water, and mechanical stirring is continuously performed for 6-12 hours to obtain the magnesium oxide partially stabilized zirconia slurry; Further comprising one or more of the following S1-S12: S1. In step (1), zirconium oxychloride crystals with a mass fraction of 99.5-99.9% are selected; S2. In step (1), fast filter paper with a pore size of 80-120 μm is used to remove insoluble substances and other impurities; S3. In step (2), the temperature of the hot water is 60-70℃; S4. In step (2), the precipitate is repeatedly washed with hot water 7-15 times on slow filter paper with a pore size of 1-3 μm; S5. In step (3), the wet milling solvent is anhydrous ethanol or high-purity water; S6. In step (3), the ball mill is a superfine ball mill; S7. In step (3), the calcination process is performed in an electric resistance furnace; S8. The amount of wet milling solvent added is 50% of the mass of the powder; S9. In step (4), the dispersant is selected from AD8098 or ethylene glycol; S10. In step (4), high-precision electroformed screen mesh is used for powder sieving; S11. Steps (1)-(5) are performed in a clean environment with a cleanliness level of 1000 or above; S12. In step (4), the powder accounts for 8-12% of the volume fraction of the mixed solution.

2. Use according to claim 1, characterized in that, The magnesium oxide partially stabilized zirconia slurry is used for grinding and removing GaSb substrates before mechanical stirring.

3. Use according to claim 1, characterized in that, The method for grinding removal includes: fixing the GaSb substrate to be treated on the bottom of a grinding carrier, adjusting the pressure to 150 g, and placing the grinding carrier on a grinding disc; using the slurry in claim 1, adjusting the liquid output rate of the slurry to 6 ml / min, and starting the uniform rotation of the bottom disc at 10 rpm; after reaching the set removal value of the substrate, taking down the GaSb substrate and washing it clean.

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