Diamond abrasive grains for ultra-precision grinding and their manufacturing method

Abstract

The present invention relates to diamond abrasive grains and a manufacturing method thereof, and provides tetradecahedral diamond abrasive grains with uniform size and shape. The manufacturing method of diamond abrasive grains according to the present invention allows for shape control and minimizes impurities and crystal defects, thereby manufacturing diamond abrasive grains for ultra-precision grinding in chemical mechanical planarization (CMP) processes.

Description

[Technical Field]

[0001] The present invention relates to diamond abrasive grains and a manufacturing method thereof, and more particularly to diamond abrasive grains for ultra-precision grinding for chemical mechanical planarization (CMP) processes and a manufacturing method thereof. [Background technology]

[0002] Planarization technology used in semiconductor manufacturing processes improves the integration of elements and ensures the structural and electrical reliability of semiconductor chips, and has become an important technology for realizing multi-layering and high integration. However, as elements become more highly integrated and the minimum line width decreases, conventional planarization technology has reached its limits, and a more precise planarization technology is needed.

[0003] Among planarization technologies, Chemical Mechanical Planarization (CMP) is the most revolutionary process applicable to next-generation semiconductor processes, and the development of diamond pad conditioners for the CMP process has emerged to achieve higher efficiency. Diamond pad conditioners for the CMP process prevent the polishing pad surface from hardening and becoming smooth by dressing and scraping the surface of the polishing pad, enabling fine processing.

[0004] The characteristics required for pad conditioners for the CMP process are a certain removal rate, uniformity of pad wear, appropriate pad wear speed, minimization of scratch generation, etc. In addition, to improve the dressing and scraping performance of the pad conditioner, the diamond used in the diamond pad conditioner must have an ultra-high temperature shape.

[0005] However, conventional high-pressure, high-temperature diamond synthesis methods have limitations in ultra-high-temperature diamond synthesis due to equipment damage and unstable yields, and the size and shape of diamond grits are not uniform due to the difficulty in controlling their shape. Summary of the Invention [Problem to be solved by the invention]

[0006] In order to solve the above-mentioned problems of the prior art, an object of the present invention is to provide ultra-high temperature type diamond abrasive grains with uniform shape for use in diamond pad conditioners for CMP processes.

[0007] Another object of the present invention is to provide diamond abrasive grains with minimized surface impurities and crystal defects for use in diamond pad conditioners for CMP processes.

[0008] Another object of the present invention is to provide a method for producing ultra-high temperature diamond abrasive grains for diamond pad conditioners used in CMP processes.

[0009] Another object of the present invention is to provide a method for manufacturing diamond abrasive grains that can control the shape of the diamond abrasive grains for use in diamond pad conditioners for CMP processes.

[0010] Another object of the present invention is to provide a method for manufacturing diamond abrasive grains that can effectively remove impurities and defective crystals for use in diamond pad conditioners for CMP processes. [Means for solving the problem]

[0011] One aspect of the present invention provides tetradecahedral diamond abrasive grains synthesized by a high pressure, high temperature process and having an aspect ratio of 0.87 or greater.

[0012] The diamond abrasive grains may be used in a pad conditioner for a chemical mechanical planarization (CMP) process, and the high pressure and high temperature process may be performed under pressure conditions of 6.15 to 6.65 GPa and temperature conditions of 1,555 to 1,610K.

[0013] The diamond abrasive grains may have a particle size distribution width of 15 μm or less.

[0014] The diamond abrasive grains may have an internal impurity content of 300 ppm or less, and a surface impurity content of 20 ppb or less.

[0015] Another aspect of the present invention provides a method for producing diamond abrasive grains synthesized by a high pressure, high temperature process.

[0016] The manufacturing method may include the steps of: (a) providing a cell with graphite and a catalyst; (b) applying pressure and heat to the cell; (c) recovering the synthesized diamond particles from the cell; (d) classifying the diamond particles; and (e) removing surface impurities from the diamond particles.

[0017] The cell in step (a) may be provided with a material obtained by mixing and molding graphite powder and catalyst powder, and may include a graphite disk.

[0018] The catalyst may comprise one or more selected from the group consisting of iron, nickel, chromium, cobalt, manganese, copper, zinc, and mixtures thereof.

[0019] The step (b) may be carried out under a pressure condition of 6.15 to 6.65 GPa and a temperature condition of 1,555 to 1,610K.

[0020] Step (b) may be carried out using a belt-type device. [Effects of the Invention]

[0021] According to one embodiment of the present invention, it is possible to provide ultra-high temperature diamond abrasive grains having a uniform tetradecahedral shape.

[0022] Furthermore, according to one embodiment of the present invention, it is possible to provide diamond abrasive grains with few impurities and crystal defects.

[0023] Furthermore, according to one embodiment of the present invention, it is possible to provide a method for manufacturing diamond abrasive grains that allows synthesis of ultra-high temperature diamond and control of the shape of the diamond abrasive grains.

[0024] Furthermore, according to one embodiment of the present invention, it is possible to provide a method for manufacturing diamond abrasive grains that can effectively remove impurities and defective crystals. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 2 is a diagram showing a schematic diagram of the correlation between the shape of diamond particles and temperature and pressure conditions.

[0026] [Figure 2] FIG. 2 is a diagram showing a schematic diagram of a cell used in a method for manufacturing diamond abrasive grains according to one embodiment of the present invention.

[0027] [Figure 3] 1 is a diagram showing a schematic diagram of an apparatus used in a method for manufacturing diamond abrasive grains according to one embodiment of the present invention.

[0028] [Figure 4] FIG. 2 is a diagram showing the results of observing diamond abrasive grains according to one embodiment of the present invention with a scanning electron microscope (SEM). DETAILED DESCRIPTION OF THE INVENTION

[0029] The present invention will be described in detail below with reference to examples. However, these examples are intended to illustrate the present invention and should not be construed as limiting the scope of the present invention to these examples.

[0030] According to one aspect of the present invention, there is provided diamond abrasive grains synthesized by a high pressure, high temperature process.

[0031] In the present invention, the diamond abrasive grains have a tetradecahedral shape.

[0032] Industrial diamonds are produced under high-pressure, high-temperature conditions, and their size and shape are determined by the temperature and pressure.

[0033] Figure 1 shows the shapes of diamonds that can be synthesized under various temperature and pressure conditions. Referring to Figure 1, when the synthesis step is performed under low pressure and temperature conditions, the shape of the synthesized diamond particles is close to a hexahedron (100), but as the pressure and temperature conditions increase, the shape becomes closer to an octahedron, forming crystal faces (111).

[0034] The tetradecahedral diamond abrasive grains of the present invention are preferably synthesized under temperature and pressure conditions in which the (111) crystal face is developed, as shown in Figure 1. In the present invention, the tetradecahedral diamond refers to a shape in which an octahedron consisting of eight {111} crystal faces has a {100} crystal facet at each vertex. In the present invention, the {100} crystal facet may occupy a very small area of ​​the surface area of ​​the diamond abrasive grains.

[0035] In the present invention, the diamond abrasive grains may have an aspect ratio of 0.87 or more. In the present invention, the aspect ratio of the diamond abrasive grains represents the ratio of the shortening to the long axis of the abrasive grains, and the closer the aspect ratio is to 1, the closer the particle is to a circle, and the larger the difference in size between the long axis and the shortening, the closer the aspect ratio is to 0.

[0036] In the present invention, the shape value of the diamond abrasive grains may be measured using Diashape (DIASHAPE, ISTAG, Switzerland).

[0037] Specifically, 2 cts of sample is evenly scattered on a sample holder so that the particles are not densely packed, and then the sample holder is placed in a carrier and attached to a scanner to scan the image. The scanned image is analyzed using software, and the shape values ​​are quantified and output.

[0038] In the present invention, the shape number of the diamond abrasive grains may be 0.87 or more, 0.88 or more, 0.89 or more, or 0.90 or more. Also, in the present invention, the shape number may be 0.95 or less, 0.93 or less, or 0.91 or less.

[0039] The diamond abrasive grains of the present invention have a high shape value, so that the ratio of the long and short axes is similar, and diamond abrasive grains that are close to circular and highly uniform can be provided.

[0040] The diamond abrasive grains of the present invention may be used in a diamond pad conditioner for a chemical mechanical planarization (CMP) process. In one embodiment, the diamond abrasive grains may be electrodeposited on the pad conditioner.

[0041] In the present invention, the diamond abrasive grains may be synthesized by a high-pressure, high-temperature process carried out under pressure conditions of 6.15 to 6.65 GPa and temperature conditions of 1,555 to 1,610 K. As a result, the diamond abrasive grains can be manufactured into a tetradecahedron shape having a shape number close to 1, and can have a uniform size and shape.

[0042] The diamond abrasive grains of the present invention may have a low particle size distribution width, as defined by the following formula:

[0043] (Formula 1)

[0044] Particle size distribution width=D90-D10

[0045] In Equation 1, D10 refers to the particle size corresponding to 10% of the cumulative volume from the smallest particle size, and D90 refers to the particle size corresponding to 90% of the cumulative volume. In the present invention, D90 and D10 may be calculated using a RO-TAP Sieve Shaker (WSTyler, USA).

[0046] Specifically, stack sieves according to the sieve arrangement table and record the weight of each open sieve. The weight of each mesh is placed in the stacked sieves and sieved for 15 minutes. The weight of the filled sieve is recorded, and the weight of the filled sieve is subtracted from the weight of the open sieve to calculate the weight. The weight percentage of each sieve is then calculated to calculate the particle size distribution.

[0047] In the present invention, the diamond abrasive grains may have a particle size distribution width of 15 μm or less. In the present invention, the diamond abrasive grains may have a particle size distribution width of 15 μm or less, 14 μm or less, 13 μm or less, 12 μm or less, or 11 μm or less.

[0048] As a result, the diamond abrasive grains of uniform size and shape electrodeposited on the pad conditioner come into point or line contact with the pad, improving the grinding ability and increasing the number of contact points, thereby improving the cutting rate.

[0049] In the present invention, the particle size distribution width may be 7 μm or more, 8 μm or more, or 9 μm or more.

[0050] The diamond abrasive grains of the present invention may have an internal impurity concentration of 300 ppm or less. In the present invention, the concentration of internal impurities may be 300 ppm or less, 250 ppm or less, 200 ppm or less, 150 ppm or less, or 100 ppm or less.

[0051] Furthermore, the diamond abrasive grains of the present invention may have a surface impurity concentration of 20 ppb or less. In the present invention, the concentration of the surface impurities may be 20 ppb or less, 15 ppb or less, 13 ppb or less, 10 ppb or less, 8 ppb or less, or 6 ppb or less.

[0052] In the present invention, the concentration of impurities may be measured by a magnetic analyzer (Magnetic Analyzer, Particulate Systems, USA).

[0053] In the present invention, minimizing the concentration of impurities enables efficient electrodeposition of diamond abrasive grains on the pad conditioner, improving tool life. In particular, processing heat is generated during pad conditioner processing. If the concentration of impurities inside the diamond is high, the diamond abrasive grains may break due to expansion caused by heat generation. By controlling the concentration of internal impurities, such breakage can be prevented, improving tool life.

[0054] Another aspect of the present invention provides a method for producing diamond abrasive grains synthesized by a high pressure, high temperature process.

[0055] The manufacturing method may include providing a cell with graphite and a catalyst, applying pressure and heat to the cell, recovering the synthesized diamond particles from the cell, sorting the diamond particles, and removing surface impurities from the diamond particles.

[0056] The manufacturing method of the present invention includes providing a cell with graphite and a catalyst.

[0057] The cells may comprise a molded mixture of graphite powder and catalyst powder, or may be stacks of alternating graphite and catalyst discs.

[0058] FIG. 2 is a diagram illustrating a cell provided in a cell providing step according to an embodiment of the present invention.

[0059] Referring to FIG. 2, the cell may include an inner heat insulating tube having a material formed by mixing graphite powder and catalyst powder therein, a heater in contact with the outer periphery of the inner heat insulating tube, and an outer heat insulating tube in contact with the outer periphery of the heater.

[0060] The catalyst may contain one or more selected from the group consisting of iron, nickel, chromium, cobalt, manganese, copper, zinc, and mixtures thereof. Preferably, the catalyst may be iron, which has the highest reactivity with graphite.

[0061] The present invention involves synthesizing diamond particles under high pressure and high temperature conditions using the cell described above.

[0062] The synthesis step may be carried out under a pressure condition of 6.15 to 6.65 GPa. In the present invention, the pressure condition of the synthesis step may be 6.15 GPa or more, 6.17 GPa or more, 6.19 GPa or more, or 6.21 GPa or more, and may be 6.65 GPa or less, 6.60 GPa or less, 6.55 GPa or less, 6.53 GPa or less, 6.51 GPa or less, or 6.49 GPa or less.

[0063] The synthesis step may be carried out at a temperature of 1,555 to 1,610 K. In the present invention, the temperature condition of the synthesis step may be 1,555 K or higher, 1,557 K or higher, or 1,559 K or higher, and may be 1,610 K or lower, 1,605 K or lower, 1,600 K or lower, or 1,595 K or lower.

[0064] In the present invention, the synthesis step may be carried out under a pressure condition of 6.15 to 6.65 GPa and a temperature condition of 1,555 to 1,610 K, to produce tetradecahedral diamond particles.

[0065] In addition, the synthesis step may be carried out for 2100 to 2300 seconds. In the present invention, the synthesis step may be carried out for 2100 seconds or more, 2120 seconds or more, 2140 seconds or more, 2160 seconds or more, or 2180 seconds or more, or for 2300 seconds or less, 2280 seconds or less, 2260 seconds or less, 2240 seconds or less, or 2220 seconds or less.

[0066] In the present invention, the synthesis step may be carried out using a belt-type apparatus.

[0067] FIG. 3 is a schematic diagram of an apparatus used in a synthesis step according to one embodiment of the present invention.

[0068] Referring to FIG. 3, the apparatus may include a carbide die within which the cell can be placed, a steel ring surrounding the carbide die, and a carbide anvil having a protruding end.

[0069] The device places the cell inside a carbide die, pressurizes the anvil until a target pressure is reached, supplies current to the heater to heat up to the target temperature, and maintains the temperature for a predetermined period of time, thereby synthesizing diamond particles.

[0070] In the apparatus, the carbide anvil can apply pressure to the cell and also supply current to the heater, and the carbide die and steel ring can support the cell horizontally.

[0071] The body of the equipment used in the present invention is made of cast iron and is forged. Conventional high-temperature, high-pressure synthesis equipment is manufactured using a casting method, which reduces the durability of the equipment body at ultra-high temperatures and pressures, posing a risk of breakage and unstable yields. The equipment of the present invention manufactures a cast iron body using a forging method rather than a casting method, which allows the synthesis step to be carried out at ultra-high temperatures of 1,500 K or more, making it possible to produce ultra-high-temperature diamond abrasive grains.

[0072] The manufacturing method of the present invention may include a step of recovering the synthesized diamond particles from the cell, classifying them by shape, and removing surface impurities from the particles. [Example]

[0073] Hereinafter, a method for manufacturing diamond abrasive grains according to one embodiment of the present invention and the diamond abrasive grains manufactured by the method will be described in detail.

[0074] The synthesis step was carried out for 2200 seconds under the pressure and temperature conditions in Table 1 below to produce diamond abrasive grains of 80 / 100 mesh size.

[0075] Specifically, 50% graphite and 50% catalyst by weight were mixed for 5 hours, then loaded into a 200-ton press and compacted at 150 tons of pressure. As shown in Figure 2, the compact was then assembled with an insulated tube and heater to form a cell. The cell was then loaded into the apparatus shown in Figure 3, and pressurized and heated to the pressure and temperature conditions shown in Table 1, maintaining this condition for 2,200 seconds. The cell was then heated at 100°C for 10 hours in aqua regia, and the diamond particles were separated from the cell. The recovered diamond particles were then heated at 100°C for 10 hours in 98% sulfuric acid to remove any remaining graphite. The diamond abrasive grains were then magnetically separated to produce diamond abrasive grains.

[0076] [Table 1]

[0077] The shape values ​​of the examples and comparative examples measured using Diamond Shape are shown in Table 1 above, and Figure 4 shows photographs of the examples and comparative examples observed with a scanning electron microscope (SEM), with (a) in Figure 4 being a photograph of the diamond abrasive grains produced in Comparative Example 4, (b) being a photograph of Comparative Example 8, and (c) being a photograph of the diamond abrasive grains produced in Example 7.

[0078] As shown in Table 1 and Figure 4, in the examples, the shape number was 0.87 or more, confirming that the crystals were formed into a tetradecahedron shape. In contrast, in Comparative Examples 1 to 7, which were synthesized under pressure conditions of 5.00 to 5.26 GPa and temperature conditions of 1,350 to 1,435 K, few crystal faces were formed, and the shape number was confirmed to be less than 0.84. Furthermore, in Comparative Examples 8 to 14, which were synthesized under pressure conditions of 5.29 to 6.12 GPa and temperature conditions of 1,453 to 1,551 K, tetradecahedron shapes were partially confirmed, but the size and shape were not uniform, and the shape number was less than 0.87.

[0079] From Table 1 and FIG. 4, it can be seen that the diamond abrasive grains according to the present invention have a shape value of 0.87 or more, a tetradecahedral shape, and have a uniform size and shape. [Industrial Applicability]

[0080] The present invention is applicable to synthetic diamond abrasive grains.

Claims

1. It is synthesized through a high-pressure, high-temperature process. The aspect ratio is 0.87 or more. 14-sided diamond abrasive grains.

2. 10. The diamond abrasive grain of claim 1, wherein the diamond abrasive grain is used in a pad conditioner for a chemical mechanical planarization (CMP) process.

3. The diamond abrasive grains according to claim 1, wherein the high pressure, high temperature process is carried out under pressure conditions of 6.15 to 6.65 GPa and temperature conditions of 1,555 to 1,610 K.

4. The diamond abrasive grains according to claim 1, wherein the diamond abrasive grains have a particle size distribution width of 15 μm or less.

5. The diamond abrasive grain according to claim 1, wherein the internal impurities of the diamond abrasive grain are 300 ppm or less.

6. The diamond abrasive grains according to claim 1, wherein the surface impurities of the diamond abrasive grains are 20 ppb or less.

7. (a) providing a cell comprising graphite and a catalyst; (b) applying pressure and heat to the cell; (c) recovering the synthesized diamond particles from the cell; (d) classifying the diamond particles; (e) removing surface impurities from the diamond particles; A method for producing diamond abrasive grains, comprising:

8. 8. The method for manufacturing diamond abrasive grains according to claim 7, wherein the cells in step (a) are provided with a material obtained by mixing and molding graphite powder and catalyst powder.

9. The method for producing diamond abrasive grains according to claim 7, wherein the cell in step (a) contains a graphite disk.

10. The method for producing diamond abrasive grains according to claim 7, wherein the catalyst comprises one or more selected from the group consisting of iron, nickel, chromium, cobalt, manganese, copper, zinc, and mixtures thereof.

11. The method for manufacturing diamond abrasive grains according to claim 7, wherein step (b) is carried out under a pressure condition of 6.15 to 6.65 GPa.

12. The method for producing diamond abrasive grains according to claim 7, wherein step (b) is carried out at a temperature of 1,555 to 1,610 K.

13. The method for producing diamond abrasive grains according to claim 7, wherein step (b) is carried out using a belt-type device.

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