Cerium oxide powder, dispersion method and chemical mechanical polishing solution

Abstract

The invention provides cerium oxide powder, a dispersion method and a chemical mechanical polishing solution. The invention discloses a dispersion method of cerium oxide powder, which comprises the following steps: preparing slurry with the cerium oxide powder content of 10-20wt% and the pH value of 5-6, grinding the slurry by adopting a gap between an annular rotor and an annular stator which can move relative to each other, arranging the annular stator on the outer side of the annular rotor in a surrounding manner, the gap distance between the annular rotor and the annular stator is 0.1-1 mm, and the D50 particle size of the ground cerium oxide powder is 150 nm or less. The cerium oxide powder prepared by the preparation method disclosed by the invention is relatively low in metal impurity content. The prepared polishing solution has an excellent silicon dioxide removal rate and a proper silicon dioxide / silicon nitride selection ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of polishing liquids. More specifically, the present invention relates to a cerium oxide powder, a dispersion method, and a chemical mechanical polishing liquid. Background Art

[0002] STI is a key technology for device isolation in semiconductor manufacturing. Its main steps include etching shallow trenches on a pure silicon wafer, depositing silicon dioxide, and then using chemical mechanical polishing (CMP) technology for surface planarization. Due to its unique chemical activity, cerium oxide has a high removal efficiency for silicon dioxide and a high selectivity ratio of silicon dioxide to silicon nitride. Therefore, it can effectively remove excess silicon dioxide and stop on the silicon nitride hard mask during the shallow trench isolation (STI) polishing process, achieving the precise formation of the STI structure and being one of the key materials in this process.

[0003] Currently, cerium oxide abrasives are mainly divided into the calcination method and the sol method. The former is prepared by sintering and pulverization, with irregular morphology, many sharp corners, high cutting action and grinding rate, and is suitable for processes with high grinding amounts; the latter is prepared by aqueous phase reaction, sedimentation, washing, and redispersion, with regular morphology, smooth surface, and less scratching, and is suitable for advanced processes with fewer defects.

[0004] During the calcination process of cerium oxide, agglomerated particles often form. Therefore, a dispersion process is required to disperse the micron-sized cerium oxide particles after calcination to the nanoscale. The current main nanoscale dispersion process is sand grinding. This process selects appropriate grinding media balls and crushes the particles in the slurry through high-speed impact and shear action. However, the calcined cerium oxide will agglomerate into large particles with high hardness. During the ball milling process, the collision between the grinding media balls and the cerium oxide particles will inevitably cause wear of the grinding media balls and introduce impurities in the grinding media balls on the surface of the abrasive, affecting the chemical activity of the cerium oxide abrasive. Summary of the Invention

[0005] An object of the present invention is to solve at least the above problems and provide at least the advantages described later.

[0006] Another object of the present invention is to provide a dispersion method for cerium oxide powder, which can obtain cerium oxide powder with a low metal impurity content. The present invention provides a polishing liquid, which has an excellent silicon dioxide removal rate and a suitable silicon dioxide / silicon nitride selectivity ratio.

[0007] To achieve these objects and other advantages according to the present invention, a method for dispersing cerium oxide powder is provided, comprising the following steps: preparing a slurry with a cerium oxide powder content of 10-20 wt% and a pH of 5-6, and dispersing the slurry by impact and high shear force in the gap between a rotatable annular rotor and an annular stator, wherein the annular stator is disposed around the outside of the annular rotor, the gap distance between the annular rotor and the annular stator is 0.1-1 mm, the D50 particle size of the cerium oxide powder after grinding is below 150 nm, and the dispersion coefficient of the cerium oxide powder is 1.293-1.408.

[0008] Preferably, the linear velocity of the annular rotor is 40-50 m / s.

[0009] Preferably, the thickness of the annular rotor is 1 / 2-5 / 6 of the thickness of the annular stator.

[0010] Preferably, a plurality of protrusions are provided on both the upper and lower surfaces of the annular rotor, and a first groove is formed between two protrusions, and the extension line of the horizontal center line of the first groove is tangent to the inner wall of the central hole of the annular rotor;

[0011] Preferably, the ratio of the outer diameter of the annular rotor to the diameter of the central hole is 5-8:1;

[0012] Preferably, the width of the first groove is 2-3 mm, the depth of the first groove is 6-7 mm, the thickness of the annular rotor is 17.5-19.5 mm, the inner diameter of the annular rotor is 78-85 mm, and the outer diameter of the annular rotor is 120-128 mm.

[0013] Preferably, a plurality of second grooves are provided on the annular stator, and the second grooves are arranged radially;

[0014] Preferably, the width of the second groove is 2.5-3.5 mm, and the depth of the second groove is 22-26 mm;

[0015] Preferably, the thickness of the annular stator is 27-32 mm, the inner diameter of the annular stator is 122-129 mm, and the outer diameter of the annular stator is 178-182 mm;

[0016] Preferably, the inner side wall of the annular stator is distributed in a sinusoidal curve-like concave-convex manner vertically upward;

[0017] Preferably, the inner sidewall of the annular stator has a sine curve function in the vertically upward direction as: y = p / 2sin(4x + π / 2) - p / 2, where x ∈ (0, h), p is the gap distance between the annular rotor and the annular stator, and h is the height of the inner sidewall of the annular stator in the vertically upward direction. The coordinate system of the sine curve function is centered at any point at the lower end of the inner sidewall of the annular stator, and the vertically upward direction of the inner sidewall of the annular stator is taken as the x-axis.

[0018] Preferably, the first groove and the second groove are misaligned and aligned, the first groove wall of the first groove is close to the second groove wall of the second groove, and the end where the first groove wall and the second groove wall are close is 2 - 4 mm apart.

[0019] Specifically, it further includes: a cover plate, which is covered above the annular stator and several protrusions.

[0020] The present invention provides a cerium oxide powder, which is prepared by the dispersion method of the above-mentioned cerium oxide powder.

[0021] The present invention provides a chemical mechanical polishing liquid, which includes cerium oxide powder, an inhibitor, a surfactant, and water.

[0022] The present invention provides a chemical mechanical polishing liquid, which includes 0.5 - 2 wt% of cerium oxide powder, 0.5 - 1.5 wt% of an inhibitor, 1 - 2 wt% of a surfactant, and the balance is water.

[0023] Preferably, the inhibitor includes one or more of hydroxamic acid, acetylhydroxamic acid, benzylhydroxamic acid, and salicylhydroxamic acid.

[0024] The present invention has at least the following beneficial effects:

[0025] The present invention uses the described annular stator and annular rotor to disperse cerium oxide powder, and can obtain cerium oxide powder with a low metal impurity content, can obtain cerium oxide powder with a wide distribution of small particle sizes, and has little influence on the removal rates of silicon dioxide and silicon nitride;

[0026] The inner sidewall of the annular stator of the present invention uses a sine function type, which can further reduce the particle size of cerium oxide powder and increase the distribution width, and provide the removal rate of silicon dioxide;

[0027] The polishing liquid prepared by the present invention has an excellent removal rate of silicon dioxide and also has a suitable removal selectivity ratio of silicon dioxide / silicon nitride.

[0028] Other advantages, objectives, and features of the present invention will be partially reflected by the following description, and partially will be understood by those skilled in the art through the research and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 Schematic structural diagram of the annular rotor and annular stator of the present invention;

[0030] Figure 2 Schematic side view structural diagram of the annular rotor of the present invention;

[0031] Figure 3 Schematic side view structural diagram of the annular stator of the present invention;

[0032] Figure 4 Schematic structural diagram of the positional relationship among the annular stator, annular rotor and cover plate of the present invention;

[0033] Figure 5 Schematic structural diagram of the dispersion device of the present invention;

[0034] Figure 6 Schematic cross-sectional structural diagram of the annular stator along the radial direction of the present invention.

[0035] Accompanying drawing indication: 1 - annular rotor, 101 - first groove, 102 - first groove wall, 2 - annular stator, 201 - second groove, 202 - second groove wall, 3 - output shaft, 4 - cover plate, 5 - dispersion device. Detailed implementation manners

[0036] The present invention provides a cerium oxide powder, a dispersion device and a polishing liquid. The following will describe the present invention in combination with specific implementation manners. For a better understanding of the technical solution of the present invention, the present invention will be specifically described below.

[0037] It should be noted that the orientation or positional relationship indicated by the terms "relative movement", "outer side wall", "outer side", "inner side wall", "inner side", "upper surface", "lower surface", "center line", "tangency", "radial direction", "vertical", "center", "close", "end", "above", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be construed as a limitation to the present invention.

[0038] The first aspect of the present invention provides a method for dispersing cerium oxide powder, including the following steps:

[0039] S1. Prepare a slurry with the cerium oxide powder content of 10 - 20 wt% and pH of 5 - 6;

[0040] In the implementation manner of the present invention, the slurry contains calcined cerium oxide particles, and the particle size of the cerium oxide powder is approximately 1 - 10 μm.

[0041] In an embodiment of the present invention, the pH of the slurry is adjusted with 1 wt% nitric acid. During the dispersion process, the slurry is always maintained at about pH 6. When the pH of the slurry changes, 1 wt% nitric acid is added to the slurry to maintain the pH between 5 and 7, preferably about 6.

[0042] S2. The slurry is dispersed by impinging and high-shearing forces in the gap between a rotatable annular rotor 1 and an annular stator 2. The dispersion process lasts for 6 - 18 h. The annular stator 2 is disposed around the outside of the annular rotor 1. The gap distance between the annular rotor 1 and the annular stator 2 is 0.1 - 1 mm. After dispersion, the D50 particle size of the cerium oxide powder is below 150 nm, and the dispersion coefficient of the cerium oxide powder is 1.293 - 1.408.

[0043] In an embodiment of the present invention, the gap between the annular rotor 1 and the annular stator 2 is 0.1 - 1 mm, preferably 0.1 - 0.5 mm. During the rotation of the annular rotor 1, a strong shearing force can be generated, causing the cerium oxide particles to be crushed and separated.

[0044] In an embodiment of the present invention, the annular stator 2 is made of superhard materials, including titanium carbonitride ceramics, tungsten carbide ceramics, and zirconia ceramics. The Vickers hardness values of the three are 2500 - 3200 HV, 1700 - 2200 HV, and 1000 - 1300 HV respectively. The annular rotor 1 can be processed and formed from the same material as the annular stator 2 or engineering plastics such as nylon and PEEK. The measurement method of Vickers hardness is as follows: with a load within 120 kg and a diamond square pyramid with a vertex angle of 136° pressed into the material surface to leave a pit, dividing the surface area of the material indentation pit by the load value gives the Vickers hardness HV value (kgf / mm 2 ).

[0045] In an embodiment of the present invention, the linear velocity of the annular rotor 1 is 40 - 50 m / s. The rapid movement can cause the cerium oxide particles to rapidly impinge on the inner wall of the annular stator 2, causing the aggregated cerium oxide particles to be crushed and separated.

[0046] In an embodiment of the present invention, nitric acid is added to the slurry at regular intervals to maintain the pH of the slurry in the dispersion device 5 between 5 and 7, preferably with a pH value of 6.

[0047] In an embodiment of the present invention, the thickness of the annular rotor 1 is 1 / 2 - 5 / 6 of the thickness of the annular stator 2. During actual use, the lower surfaces of the annular rotor 1 and the annular stator 2 are on the same plane, and the upper surface of the annular rotor 1 is lower than the upper surface of the annular stator 2, so that the slurry can quickly enter the working area of the annular rotor 1 and the annular stator 2 and quickly complete the dispersion of the cerium oxide powder in the slurry.

[0048] In an embodiment of the present invention, a plurality of protrusions are provided on both the upper surface and the lower surface of the annular rotor 1. A first groove 101 is formed between two adjacent protrusions. The extension line of the horizontal center line of the first groove 101 is tangent to the inner wall of the central hole of the annular rotor 1. The plurality of protrusions extend from the 1 / 3 to 1 / 2 of the radial direction of the annular rotor 1 to the radial end of the annular rotor 1. During the working process, the rotation direction of the annular rotor 1 is opposite to the direction of the first groove 101. At this time, the slurry entering the first groove 101 can be thrown out more quickly. The greater the speed, the greater the impact force on the inner side wall of the annular stator 2, and the better the pulverizing effect on the cerium oxide powder.

[0049] In an embodiment of the present invention, the ratio of the outer diameter of the annular rotor 1 to the diameter of the central hole is 5 - 8:1; the central hole is used for inserting a bearing, and the bearing drives the annular rotor 1 to rotate rapidly.

[0050] In an embodiment of the present invention, the width of the first groove 101 is 2 - 3 mm, the depth of the first groove 101 is 6 - 7 mm, the thickness of the annular rotor 1 is 17.5 - 19.5 mm, the inner diameter of the annular rotor 1 is 78 - 85 mm, and the outer diameter of the annular rotor 1 is 120 - 128 mm. A certain interval is provided between two first grooves 101, which can reduce the cerium oxide powder hitting the inner side wall of the annular stator 2 during rotation, ensuring that the existing cerium oxide powder can fully impact the inner side wall of the annular stator 2 to achieve a better pulverizing effect on the cerium oxide powder.

[0051] In an embodiment of the present invention, a plurality of second grooves 201 are provided on the annular stator 2. The second grooves 201 are arranged radially; as the annular rotor 1 rotates, under the action of centrifugal force, the slurry will be thrown out from the second grooves 201. Due to the law of conservation of mass, other slurry will be axially replenished and loaded onto the annular rotor 1. Reciprocating in a cycle, a vortex will be formed between the annular rotor 1 and the annular stator 2, realizing high-speed shearing and impact pulverization of the slurry.

[0052] In an embodiment of the present invention, the width of the second groove 201 is 2.5 - 3.5 mm, and the height of the second groove 201 is 22 - 26 mm; preferably, the inner diameter of the annular stator 2 is 122 - 129 mm, and the outer diameter of the annular stator 2 is 178 - 182 mm; by controlling the number of the second grooves 201, the slurry can be fully dispersed between the annular rotor 1 and the annular stator 2 to achieve a further effect of shearing the cerium oxide powder, and the particle size of the cerium oxide powder obtained after dispersion can be finer.

[0053] In an embodiment of the present invention, the inner wall of the annular stator 2 is distributed in a sine - curve - like concave - convex pattern vertically upward; this can cause the particles of the cerium oxide powder to repeatedly impact on the inner wall of the annular stator 2, so as to achieve a good dispersion effect.

[0054] In an embodiment of the present invention, the sine - curve function of the inner wall of the annular stator 2 vertically upward is: y = p / 2sin(4x + π / 2)-p / 2, x ∈ (0, h), where p is the gap distance between the annular rotor and the annular stator, h is the height of the inner wall of the annular stator 2 vertically upward, h is preferably 0.85π - π cm. The coordinate system of the sine - curve function is established with an arbitrary point at the lower end of the inner wall of the annular stator 2 as the origin, the vertical direction of the inner wall of the annular stator 2 as the x - axis, and the radial direction of the annular stator 2 as the y - axis. On the inner wall of the annular stator 2 with a limited height, making the upper and lower ends of the inner wall of the annular stator 2 present a concave - convex form can further cause the particles of the cerium oxide powder to repeatedly impact on the inner wall of the annular stator 2. At the same time, the irregular slits generate high - speed turbulence and shear force between the annular stator 2 and the annular rotor 1, reducing the particle size of the cerium oxide powder and increasing the distribution width of the particle size of the cerium oxide powder, so as to achieve a better dispersion effect.

[0055] In an embodiment of the present invention, the first groove 101 and the second groove 201 are misaligned and aligned. The first groove wall 102 of the first groove 101 is close to the second groove wall 202 of the second groove 201, and the ends where the first groove wall 102 and the second groove wall 202 are close are 2 - 4 mm apart. This avoids the direct alignment of the openings of the first groove 101 and the second groove 201, which may cause the slurry to directly enter the second groove 201 and be thrown out.

[0056] In an embodiment of the present invention, it further includes: a cover plate 4, which covers the first groove 101 and the second groove 201, so that the slurry enters from the first groove 101, impacts the inner wall of the annular stator 2, and then discharges from the second groove 201 to achieve a dispersion effect. There is no contact between the cover plate 4 and the first groove 101, and there is a cavity. In order to accommodate a small amount of slurry, when the particles are dispersed, the slurry can be continuously and quickly replenished into the first groove 101.

[0057] Based on the description of the above - mentioned embodiments, the description of this embodiment further reflects that the present invention can be implemented.

[0058] In the first embodiment of the present invention, a slurry with a cerium oxide powder content of 10 - 20 wt% and a pH of 5 - 6 is prepared. The slurry is placed in a dispersion device 5. The dispersion device 5 is an openable and closable closed container that can hold the slurry. The dispersion device 5 is made of titanium carbonitride ceramic material. As Figure 5As shown, the annular stator 2 and the annular rotor 1 are located at the bottom of the dispersion device 5, and the annular stator 2 and the annular rotor 1 are horizontally arranged. As Figure 1 shown, the annular stator 2 is arranged around the outside of the annular rotor 1. The gap distance between the annular rotor 1 and the annular stator 2 is 0.1 - 1 mm. The annular rotor 1 is fixed on the output shaft 3 of the motor through the central hole in the middle. The annular rotor 1 is driven by the motor to rotate. The motor is arranged below the annular rotor 1 inside the dispersion device 5. A plurality of protrusions are provided on both the upper surface and the lower surface of the annular rotor 1. A plurality of first grooves 101 are formed between two adjacent protrusions. As Figure 2 shown, the first grooves 101 on the upper and lower surfaces of the annular rotor 1 are arranged staggeredly. As Figure 3 shown, a plurality of second grooves 201 are provided on the annular stator 2. As Figure 4 shown, the cover plate 4 is covered above the annular stator 2 and a plurality of protrusions. The cover plate 4 does not contact the plurality of protrusions. A cavity is formed between the cover plate 4 and the upper surface of the annular rotor 1. The bottom of the dispersion device 5 is filled with PEEK material, and the filling height is flush with the lower surface of the annular stator 2. The annular rotor 1 is fixed on the output shaft 3 of the motor. The filled PEEK does not restrict the rotation of the output shaft 3. The part of the upper surface of the filled PEEK in contact with the output shaft 3 adopts a shaft seal or a mechanical seal to prevent the slurry from entering the gap between the output shaft 3 and the PEEK. During the working process, the linear velocity of the annular rotor 1 can be as high as about 40 - 50 m / s. The specific working process is as follows: The slurry axially enters from the hollow part in the middle of the cover plate 4. The motor starts, and the motor drives the annular rotor 1 to rotate. Due to the action of centrifugal force, the liquid enters the first grooves 101 in the radial direction and sprays onto the inner side wall of the annular stator 2. The slurry carrying the cerium oxide powder impacts with the annular stator 2. At the same time, the 0.1 - 1 mm slit between the annular rotor 1 and the annular stator 2 can generate a high-speed shearing force to tear the particles. Finally, the slurry is discharged from the second grooves 201 of the annular stator 2. Due to the law of conservation of mass, the slurry will be axially replenished and loaded onto the annular rotor 1 from the hollow part of the cover plate 4, and the cycle repeats to form a vortex, completing the dispersion work of the slurry. Then it is filtered. The filtration is carried out using two meshes of filter elements. First, a large filter element with 1 μm is used for filtration, and then a small filter element with 0.5 μm is used for filtration. After filtration, centrifugation is carried out at a speed of 5000 - 5500 rpm / min, and the supernatant is taken to obtain the cerium oxide powder with the required particle size.

[0059] In the second embodiment of the present invention, based on the first embodiment, as Figure 6As shown in the figure, an annular stator 2 with a sinusoidal curve-shaped concave-convex inner wall is used. The sinusoidal curve function is: y = p / 2sin(4x + π / 2) - p / 2, where x ∈ (0, h), p is the gap distance between the annular rotor and the annular stator, and h is the vertical height of the inner wall of the annular stator 2. h is preferably 0.85π to π cm. The coordinate system of the sinusoidal curve function is established with an arbitrary point at the lower end of the inner wall of the annular stator 2 as the origin, the vertical direction of the inner wall of the annular stator 2 as the x-axis, and the radial direction of the annular stator 2 as the y-axis. On the inner wall of the annular stator 2 with a limited height, making the upper and lower ends of the inner wall of the annular stator 2 present a concave-convex form can further cause the particles of the cerium oxide powder to repeatedly impact on the inner wall of the annular stator 2. At the same time, the irregular slit shape is conducive to generating high-speed turbulent flow, forming a strong shear force, further reducing the particle size of the cerium oxide powder, increasing the distribution width of the particle size of the cerium oxide powder, and achieving a better grinding effect on silicon dioxide.

[0060] Based on the above dispersion method of cerium oxide powder, the cerium oxide powder prepared by the present invention has an extremely low metal impurity content. Metal impurities are likely to form complexes with the components in the polishing liquid, significantly reducing the grinding rate of cerium oxide abrasive on silicon dioxide. Based on this, after the cerium oxide powder prepared by the dispersion method of the present invention is prepared into a polishing liquid, it has little influence on the removal rates of silicon dioxide and silicon nitride.

[0061] The second aspect of the present invention provides a cerium oxide powder, which is prepared by the above dispersion method of cerium oxide powder. In an embodiment of the present invention, the D50 particle size of the cerium oxide powder of the present invention is below 150 nm.

[0062] The third aspect of the present invention provides a chemical mechanical polishing liquid, which includes the cerium oxide powder prepared by the above dispersion method, an inhibitor, polyethylene glycol, and water.

[0063] In an embodiment of the present invention, the polishing liquid of the present invention includes 0.5 to 2 wt% of cerium oxide powder, 0.5 to 1.5 wt% of inhibitor, 1 to 2 wt% of surfactant, and water.

[0064] In an embodiment of the present invention, the inhibitor includes one or more of hydroxamic acid, acetyl hydroxamic acid, benzyl hydroxamic acid, and salicyl hydroxamic acid, and can reduce the removal rate of silicon nitride.

[0065] In an embodiment of the present invention, the surfactant includes one or two of polyethylene glycol or 1-butanol, which can obtain a stable dispersion effect for the cerium oxide powder and will not cause agglomeration.

[0066] In an embodiment of the present invention, it was unexpectedly found that the use of hydroxamic acid inhibitors can maintain the removal rate of silica and increase the selectivity ratio of the removal rate of silica to that of silicon nitride.

[0067] The following examples are used to further illustrate the present invention in detail, so that those skilled in the art can implement it with reference to the text of the specification.

[0068] It should be noted that the experimental methods described in the following embodiments are all conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial sources unless otherwise specified.

[0069] <Preparation Example 1>

[0070] S1. Calcination preparation of cerium oxide

[0071] Take 3 kg of cerium carbonate and place it in a muffle furnace. Calcinate it at 700 °C for 2 h to obtain about 1.5 kg of solid powder. Analyze its crystal phase by XRD and judge it to be cerium oxide. The particle size of cerium oxide is about between 1 and 2 μm.

[0072] S2. Preparation of slurry

[0073] Take 1 kg of cerium oxide prepared in step S1, add deionized water, and prepare a slurry with a cerium oxide content of 15 wt%. Adjust the pH of the slurry to 5 - 6 with 1 wt% nitric acid.

[0074] S3. Dispersion of powder

[0075] Place the slurry into a dispersion device, turn on the motor, adjust the linear velocity of the annular rotor to 40 m / s. Every 5 minutes, add 1 wt% nitric acid to the slurry to maintain the pH around 6 and keep the particles in a suspended state. Disperse at high speed for 8 h, filter, and centrifuge. The centrifuge rotates at a speed of 5000 - 5500 rpm / min. Take the supernatant to obtain cerium oxide powder with a D50 particle size of less than 150 nm, and the dispersion coefficient of the cerium oxide powder is 1.287. Use the dispersion device in the first embodiment.

[0076] <Preparation Example 2>

[0077] S1. Calcination preparation of cerium oxide

[0078] Take 3 kg of cerium carbonate and place it in a muffle furnace. Calcinate it at 700 °C for 2 h to obtain about 1.5 kg of solid powder. Analyze its crystal phase by XRD and judge it to be cerium oxide. The particle size of cerium oxide is about between 1 and 2 μm.

[0079] S2. Preparation of slurry

[0080] Take 1 kg of cerium oxide prepared in step S1, add deionized water to prepare a slurry with a cerium oxide content of 15 wt%, and adjust the pH of the slurry to 5 - 6 using 1 wt% nitric acid.

[0081] S3. Dispersion of the powder

[0082] Place the slurry into a dispersion device, turn on the motor, adjust the linear velocity of the annular rotor to 48 m / s. Every 5 minutes, add 1 wt% nitric acid to the slurry to maintain the pH around 6 and keep the particles in a suspended state. Disperse at high speed for 10 h, filter, centrifuge at a speed of 5000 - 5500 rpm / min, take the supernatant, and precipitate to obtain cerium oxide powder with a D50 particle size of less than 150 nm. The dispersion coefficient of the cerium oxide powder is 1.302. Use the dispersion device in the first embodiment.

[0083] <Preparation Example 3>

[0084] S1. Calcination preparation of cerium oxide

[0085] Take 3 kg of cerium carbonate and place it in a muffle furnace, calcine at 700 °C for 2 h to obtain about 1.5 kg of solid powder. Analyze its crystal phase by XRD and determine it to be cerium oxide. The particle size of the cerium oxide is about between 1 - 2 μm.

[0086] S2. Preparation of the slurry

[0087] Take 1 kg of cerium oxide prepared in step S1, add deionized water to prepare a slurry with a cerium oxide content of 15 wt%, and adjust the pH of the slurry to 5 - 6 using 1 wt% nitric acid.

[0088] S3. Dispersion of the powder

[0089] Place the slurry into a dispersion device, turn on the motor, adjust the linear velocity of the annular rotor to 48 m / s. Every 5 minutes, add 1 wt% nitric acid to the slurry to maintain the pH around 6 and keep the particles in a suspended state. Disperse at high speed for 10 h, filter, centrifuge at a speed of 5000 - 5500 rpm / min, take the supernatant, and precipitate to obtain cerium oxide powder with a D50 particle size of less than 100 nm. The dispersion coefficient of the cerium oxide powder is 1.392. Use the grinding device in the second embodiment.

[0090] <Comparative Example 1>

[0091] Steps S1 and S2 are the same as those in Preparation Example 1. The difference is that in Step S3, comminution is carried out by a horizontal sand mill. The sand mill is equipped with ceramic alumina beads with a particle size of 0.4 - 0.6 microns. During sand milling, an external stirring kettle is required to circulate the slurry. After sand milling, filtration is carried out. Centrifugation is carried out at a rotation speed of 5000 - 5500 rpm / min, and the supernatant is taken. The obtained cerium oxide powder has a D50 particle size of less than 200 nm, and the dispersion coefficient of the cerium oxide powder is 1.192.

[0092] <Test on metal ion content of cerium oxide powder>

[0093] Take the cerium oxide powder particles prepared in Preparation Examples 1 - 3 and Comparative Example 1, and prepare a slurry with a cerium oxide powder particle content of 5 wt%, a polyethylene glycol content of 1 wt%, and the balance being deionized water.

[0094] Take 750 mL of the slurry, and remove the particles in the slurry by high - speed centrifugation. Use a Hunan Xiangyi high - speed refrigerated centrifuge H2500R - 2, centrifuge at 5000 rpm for 40 min, take about 5 mL of the supernatant, and measure by ICP - OES. The amounts of metal ions are shown in Table 1.

[0095] Table 1

[0096] Number Al Ca Mg Fe W Na K Zr Zn Preparation Example 1 <0.01 0.02 0.02 <0.01 0.12 0.04 0.03 <0.01 <0.01 Preparation Example 2 <0.01 0.03 0.02 <0.01 0.13 0.03 0.04 <0.01 <0.01 Preparation Example 3 <0.01 0.02 0.02 <0.01 0.11 0.03 0.04 <0.01 <0.01 Comparative Example 1 63.14 1.07 0.83 0.02 <0.01 0.37 0.09 <0.01 <0.01

[0097] As can be seen from Table 1, the high - speed shear dispersion equipment with a ring rotor and a ring stator used in Preparation Examples 1 - 3 introduces fewer metal impurities. In Comparative Example 1, alumina beads were used for grinding, resulting in the entry of Al elements into the product. Among them, due to the relatively low hardness of the alumina grinding beads and their easy reaction with acids, more Al elements are precipitated, seriously affecting the purity of the product.

[0098] <Example 1>

[0099] Prepare a polishing liquid, including: 1 wt% of the cerium oxide powder in Preparation Example 1, 1 wt% of acetylhydroxamic acid, 2 wt% of 1 - butanol, and the balance being deionized water.

[0100] <Example 2>

[0101] Prepare a polishing liquid, including: 0.8 wt% of the cerium oxide powder in Preparation Example 1, 1 wt% of acetylhydroxamic acid, 2 wt% of polyethylene glycol, and the balance being deionized water.

[0102] <Example 3>

[0103] Prepare a polishing liquid, including: 1 wt% of the cerium oxide powder in Preparation Example 2, 1 wt% of acetylhydroxamic acid, 2 wt% of polyethylene glycol, and the balance being deionized water.

[0104] <Example 4>

[0105] Prepare a polishing liquid, including: 0.8 wt% of the cerium oxide powder in Preparation Example 2, 1 wt% of salicylhydroxamic acid, 2 wt% of polyethylene glycol, and the balance being deionized water.

[0106] <Example 5>

[0107] Prepare a polishing liquid, including: 1 wt% of the cerium oxide powder in Preparation Example 3, 1 wt% of acetylhydroxamic acid, 2 wt% of polyethylene glycol, and the balance being deionized water.

[0108] <Comparative Example 1>

[0109] Prepare a polishing liquid, including: 1 wt% of the cerium oxide powder in Comparative Example 1, 1 wt% of hydroxamic acid, 2 wt% of 1-butanol, and the balance being deionized water.

[0110] <Comparative Example 2>

[0111] Prepare a polishing liquid, including: 0.8 wt% of the cerium oxide powder in Comparative Example 1, 1 wt% of hydroxamic acid, 2 wt% of 1-butanol, and the balance being deionized water.

[0112] <Comparative Example 3>

[0113] Prepare a polishing liquid, including: 1 wt% of the cerium oxide powder in Preparation Example 1, 2 wt% of 1-butanol, and the balance being deionized water.

[0114] <Comparative Example 4>

[0115] Prepare a polishing liquid, including: 2.5 wt% of the cerium oxide powder in Preparation Example 1, 0.1 wt% of hydroxamic acid, 0.5 wt% of 1-butanol, and the balance being deionized water.

[0116] <Comparative Example 5>

[0117] Prepare a polishing liquid, including: 2.5 wt% of the cerium oxide powder in Preparation Example 1, 2 wt% of hydroxamic acid, 2.5 wt% of 1-butanol, and the balance being deionized water.

[0118] <Polishing Liquid Performance Test>

[0119] Polishing liquid grinding rate measurement: The polishing machine is Mirra, the polished wafer is a film wafer loaded with OX and SiN, the polishing pad is DH3410, the polishing liquid is the polishing liquid of Examples 1-5 and Comparative Examples 1-5 above, the flow rate is 300 cc / min, the dresser is a diamond disk of DS8051, the pressure is 6 lbf, the platen speed is 113 rpm, the carrier speed is 107 rpm, and the polishing head pressure is 2.0 psi. Under the above test conditions, the test wafer is ground, and the removal rates of OX and SiN are obtained from the wear reduction, and the unit is The test data of the polishing liquid are shown in Table 2.

[0120] Test method for defect density: The defect density is the count of defects measured on the wafer. The instrument used is a KLA-Tencor SP2 analyzer, and the average number of defects in 10 wafers is recorded. The test data are shown in Table 2.

[0121] Table 2

[0122]

[0123]

[0124] As can be seen from Table 2, the polishing liquids of Examples 1-5 have a high OX grinding rate and a low SiN grinding rate, and a high OX / SiN selectivity can be achieved. Thus, it can be seen that when the cerium oxide surface contains a high content of metal impurities, its OX grinding rate will be greatly affected, especially when there are substances such as amino-based SiN inhibitors in the formulation that are easy to coordinate with metals.

[0125] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and embodiments. It can be fully applied to various fields suitable for the present invention. For those skilled in the art, additional modifications can be easily made. Therefore, without departing from the general concept defined by the claims and the equivalent scope, the present invention is not limited to the specific details and the embodiments shown and described herein.

Claims

1. A method for dispersing cerium oxide powder, characterized in that, It includes the following steps: Prepare a slurry with the cerium oxide powder content of 10-20 wt% and pH of 5-6. The slurry is subjected to impact grinding through the gap between a rotatable annular rotor and an annular stator. The annular stator is arranged around the outside of the annular rotor. The gap distance between the annular rotor and the annular stator is 0.1-1 mm. After grinding, the D50 particle size of the cerium oxide powder is below 150 nm, and the dispersion coefficient of the cerium oxide powder is 1.283-1.

408.

2. The dispersion method of cerium oxide powder according to claim 1, characterized in that, The linear velocity of the annular rotor is 40-50 m / s.

3. The dispersion method of cerium oxide powder according to claim 1, wherein, The thickness of the annular rotor is 1 / 2-5 / 6 of the thickness of the annular stator.

4. The dispersion method of the cerium oxide powder according to claim 1, characterized in that, A number of protrusions are arranged on both the upper surface and the lower surface of the annular rotor. A first groove is formed between two adjacent protrusions. The extension line of the horizontal center line of the first groove is tangent to the wall of the central hole of the annular rotor. Preferably, the ratio of the outer diameter of the annular rotor to the diameter of the central hole is 5-8:

1. Preferably, the width of the first groove is 2-3 mm, and the depth of the first groove is 6-7 mm. Preferably, the thickness of the annular rotor is 17.5-19.5 mm, the inner diameter of the annular rotor is 78-85 mm, and the outer diameter of the annular rotor is 120-128 mm.

5. The dispersion method of cerium oxide powder according to claim 4, characterized in that, A number of second grooves are arranged on the annular stator, and the second grooves are arranged radially. Preferably, the width of the second groove is 2.5-3.5 mm, and the depth of the second groove is 22-26 mm. Preferably, the thickness of the annular stator is 27-32 mm, the inner diameter of the annular stator is 122-129 mm, and the outer diameter of the annular stator is 178-182 mm. Preferably, the inner side wall of the annular stator is distributed in a sinusoidal curve-like concave and convex pattern vertically upward. Preferably, the sinusoidal curve function of the inner side wall of the annular stator vertically upward is: y = p / 2sin(4x + π / 2) - p / 2, x ∈ (0, h), where p is the gap distance between the annular rotor and the annular stator, h is the height of the inner side wall of the annular stator vertically upward, and the coordinate system of the sinusoidal curve function is established with any point at the lower end of the inner side wall of the annular stator as the origin and the vertical direction of the inner side wall of the annular stator as the x-axis. Preferably, the first groove and the second groove are misaligned and aligned. The first groove wall of the first groove is close to the second groove wall of the second groove, and the end where the first groove wall and the second groove wall are close is 2-4 mm apart.

6. The dispersion method of cerium oxide powder according to claim 5, characterized in that, It further includes: A cover plate, which is covered above the annular stator and a number of protrusions.

7. A cerium oxide powder, characterized in that, It is prepared by the dispersion method of the cerium oxide powder according to any one of claims 1-6.

8. A chemical mechanical polishing liquid, characterized in that, It includes the cerium oxide powder according to claim 7, an inhibitor, a surfactant, and water.

9. A chemical mechanical polishing liquid, characterized in that, It includes 0.5-2 wt% of the cerium oxide powder according to claim 7, 0.5-1.5 wt% of the inhibitor, 1-2 wt% of the surfactant, and the balance is water.

10. The chemical mechanical polishing liquid according to claim 8 or 9, characterized in that, The inhibitor includes one or more of hydroxamic acid, acetylhydroxamic acid, benzylhydroxamic acid, and salicylhydroxamic acid.

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