Diamond abrasive grains for ultra-precision grinding and method for manufacturing the same

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 method for manufacturing the same, and more particularly to diamond abrasive grains for ultra-precision grinding for a chemical mechanical planarization (CMP) process and a method for manufacturing the same.

Background Art

[0002] The planarization process technology used during semiconductor production improves the integration density of elements, aims for the structural and electrical reliability of semiconductor chips, and has become an important technology for realizing multilayer and high integration. However, as elements become highly integrated and the minimum line width decreases, the conventional planarization technology has limitations in overcoming, and a higher-precision planarization technology has become necessary.

[0003] Among planarization technologies, the most revolutionary process applicable to next-generation semiconductor processes is the chemical mechanical planarization (CMP) technology, and the development of a diamond pad conditioner for the CMP process has emerged for higher efficiency. The diamond pad conditioner for the CMP process prevents surface hardening and smoothing of the polishing pad by surface dressing and scraping of the polishing pad, enabling microfabrication.

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

[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 controlling the shape of diamond abrasive grains (grit) is difficult, resulting in inconsistent size and shape. [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] To solve the problems of the conventional technology described above, the present invention aims to provide ultra-high temperature type diamond abrasive grains with a uniform shape for use in diamond pad conditioners for CMP processes.

[0007] Furthermore, the present invention aims to provide diamond abrasive grains with minimized surface impurities and crystal defects for use in diamond pad conditioners for CMP processes.

[0008] Furthermore, the present invention aims to provide a method for manufacturing ultra-high temperature diamond abrasive grains for diamond pad conditioners used in CMP processes.

[0009] Furthermore, the present invention aims to provide a method for manufacturing diamond abrasive grains that allows for control over the shape of the diamond abrasive grains for use in diamond pad conditioners for CMP processes.

[0010] Furthermore, the present invention aims 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 14-sided diamond abrasive grains synthesized by a high-pressure, high-temperature process and having an aspect ratio of 0.87 or higher.

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

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

[0014] The internal impurities of the diamond abrasive grains may be 300 ppm or less, and the surface impurities of the diamond abrasive grains may be 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 equipped with graphite and a catalyst, (b) applying pressure and heat to the cell, (c) recovering diamond particles synthesized from the cell, (d) classifying the diamond particles, and (e) removing surface impurities from the diamond particles.

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

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

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

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

[0021] According to an embodiment of the present invention, it becomes possible to provide super-high temperature type diamond abrasive grains having a uniform 14-sided shape.

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

[0023] Also, according to an embodiment of the present invention, it becomes possible to provide a method for manufacturing diamond abrasive grains capable of synthesizing super-high temperature type diamond and controlling the shape of diamond abrasive grains.

[0024] Also, according to an embodiment of the present invention, it becomes possible to provide a method for manufacturing diamond abrasive grains capable of effectively removing impurities and defective crystals.

Brief Description of the Drawings

[0025] [Figure 1] It is a diagram schematically showing the correlation of the shape of diamond particles depending on temperature and pressure conditions.

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

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

[0028] [Figure 4] It is a diagram showing the result of observing diamond abrasive grains according to an embodiment of the present invention with a scanning electron microscope (SEM).

Modes for Carrying Out the Invention

[0029] Hereinafter, the present invention will be described in detail with reference to examples. However, these examples are for illustrative purposes of the present invention, and the scope of the present invention should not be construed as being limited to these examples.

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

[0031] In the present invention, the diamond abrasive grains have a 14-sided shape.

[0032] Industrial diamonds, manufactured under high-pressure and high-temperature conditions, have their size and shape determined by 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 carried out under low pressure and temperature conditions, the shape of the synthesized diamond particles is close to a hexahedron (100), and as the pressure and temperature conditions increase, crystal faces (111) are formed and it approaches an octahedron.

[0034] The 14-sided diamond abrasive grains of the present invention are preferably synthesized under temperature and pressure conditions in which the crystal faces (111) are well-developed, as shown in Figure 1. In the present invention, 14-sided diamond refers to a shape in which each vertex of an octahedron composed of eight {111} crystal faces (facets) is provided with a {100} crystal facet. In the present invention, the {100} crystal facet may occupy a very small area of ​​the surface area of ​​the diamond abrasive grain.

[0035] Furthermore, in the present invention, the diamond abrasive grain may have a shape value (aspect ratio) of 0.87 or higher. In the present invention, the shape value of the diamond abrasive grain is the ratio of the long axis of the abrasive grain. Short axis This represents the ratio, and the closer the shape value is to 1, the closer the particle is to a circle, and the long axis and Short axis The larger the difference in magnitude, the closer it approaches 0.

[0036] In this invention, the shape values ​​of the diamond abrasive grains may be measured using DiaShape (DIASHAPE, ISTAG, Switzerland).

[0037] Specifically, 2cts of the sample are evenly scattered onto a sample holder to prevent particle clustering. The sample holder is then placed in a carrier and attached to a scanner to scan the image. The scanned image is analyzed using software, and the resulting quantitative values ​​of the shape are output.

[0038] In the present invention, the shape value of the diamond abrasive grain may be 0.87 or higher, 0.88 or higher, 0.89 or higher, or 0.90 or higher. In addition, in the present invention, the shape value may be 0.95 or lower, 0.93 or lower, or 0.91 or lower.

[0039] The diamond abrasive grains of the present invention have high shape values, resulting in a similar ratio of long and short axes, and can provide diamond abrasive grains that are close to circular and highly uniform.

[0040] The diamond abrasive grains of the present invention may be used in a diamond pad conditioner for chemical mechanical planarization (CMP) processes. As a specific example, the diamond abrasive grains may be electroplated onto the pad conditioner.

[0041] In the present invention, the aforementioned 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 14-sided shape with a shape value 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, sieves are stacked according to the sieve arrangement table, and the weight of each empty sieve is recorded. The weight of each mesh is placed into the stacked sieves, and the sieving is performed for 15 minutes. The weight of the filled sieves is recorded, and the weight is calculated by subtracting the weight of the empty sieves from the weight of the filled sieves. Then, the weight percentage of each sieve is determined, and the particle size distribution is calculated.

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

[0048] This improves grinding performance and increases the cutting rate by allowing the uniformly sized and shaped diamond abrasive particles, which are electroplated onto the pad conditioner, to make point or line contact with the pad, thereby increasing the number of contact points.

[0049] Furthermore, 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 content 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 content of 20 ppb or less. In the present invention, the concentration of 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 this invention, the concentration of impurities may be measured using a magnetic analyzer (Magnetic Analyzer, Particulate Systems, USA).

[0053] In this invention, by minimizing the concentration of impurities, efficient electrodeposition of diamond abrasive grains to the pad conditioner is possible, improving tool life. In particular, processing heat is generated during the processing of the pad conditioner, and if the concentration of impurities inside the diamond is high, expansion caused by heat generation may cause damage to the diamond abrasive grains. By controlling the concentration of internal impurities, such damage can be prevented, and tool life can be improved.

[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 the steps of providing a cell equipped with graphite and a catalyst, applying pressure and heat to the cell, recovering diamond particles synthesized from the cell, classifying the diamond particles, and removing surface impurities from the diamond particles.

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

[0057] The cell may comprise a material obtained by mixing and molding graphite powder and catalyst powder, or it may consist of alternating layers of graphite disks and catalyst disks.

[0058] Figure 2 is a schematic diagram showing a cell provided at the cell provisioning stage according to one embodiment of the present invention.

[0059] Referring to Figure 2, the cell may be configured to include an internal insulating tube containing a material formed by mixing graphite powder and catalyst powder, a heater in contact with the outer circumference of the internal insulating tube, and an external insulating tube in contact with the outer circumference of the heater.

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

[0061] The present invention includes the step of synthesizing diamond particles under high pressure and high temperature conditions using the aforementioned cell.

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

[0063] The synthesis step may be carried out under temperature conditions of 1,555 to 1,610 K. In the present invention, the temperature conditions for 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 pressure conditions of 6.15 to 6.65 GPa and temperature conditions of 1,555 to 1,610 K to produce 14-sided diamond particles.

[0065] Furthermore, 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, and may be carried out 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 device.

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

[0068] Referring to Figure 3, the apparatus may be configured to include a carbide die in which the cells can be arranged, a steel ring surrounding the carbide die, and a carbide anvil having a protruding end.

[0069] The apparatus can synthesize diamond particles by placing the cell inside a carbide die, pressurizing the anvil to reach a target pressure, supplying current to a heater to heat it to a target temperature, and maintaining that temperature for a predetermined time.

[0070] In the above-mentioned apparatus, the carbide anvil can, in addition to applying pressure to the cell, also supply current to the heater, and the carbide die and steel ring can support the cell in the horizontal direction.

[0071] The equipment body used in this invention is made of cast iron and manufactured by a forging method. Conventional high-temperature, high-pressure synthesis equipment is manufactured by a casting method, which leads to problems such as reduced durability of the equipment body at ultra-high temperatures and pressures, the risk of breakage, and unstable yields. By manufacturing the cast iron body of the equipment of this invention by a forging method instead of a casting method, the synthesis stage can be carried out at ultra-high temperatures of 1,500K or higher, making it possible to manufacture ultra-high temperature diamond abrasive grains.

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

[0073] The following describes in detail a method for producing diamond abrasive grains according to one embodiment of the present invention and the diamond abrasive grains produced thereby.

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

[0075] Specifically, 50% by weight of graphite and 50% by weight of catalyst were mixed for 5 hours, then the mixture was placed in a 200-ton press and molded under a pressure of 150 tons. As shown in Figure 2, the molded body, insulating tube, and heater were assembled to produce a cell. After mounting the cell in the apparatus shown in Figure 3, it was pressurized and heated to the pressure and temperature conditions in Table 1 and maintained for 2200 seconds. Subsequently, it was heated in an aqueous solution at 100°C for 10 hours to separate the diamond particles from the cell. The recovered diamond particles were heated in 98% sulfuric acid at 100°C for 10 hours to remove the remaining graphite. After that, the diamond abrasive grains were produced by magnetic classification.

[0076] [Table 1]

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

[0078] As shown in Table 1 and Figure 4, the example material had a shape value of 0.87 or higher, confirming that it was formed in a 14-sided shape. In contrast, Comparative Examples 1 to 7, synthesized under pressure conditions of 5.00 to 5.26 GPa and temperature conditions of 1,350 to 1,435 K, had fewer crystal faces formed, and their shape values ​​were confirmed to be less than 0.84. Furthermore, Comparative Examples 8 to 14, synthesized under pressure conditions of 5.29 to 6.12 GPa and temperature conditions of 1,453 to 1,551 K, showed a partially confirmed 14-sided shape, but the size and shape were not uniform, and their shape values ​​were less than 0.87.

[0079] From Table 1 and Figure 4, it was found that the diamond abrasive grains according to the present invention have a shape value of 0.87 or higher, a 14-sided shape, and uniform size and shape. [Industrial applicability]

[0080] This invention is applicable to synthetic diamond abrasive grains. The aspects relating to this disclosure also include the following aspects. <1> Synthesized by a high-pressure, high-temperature process, The aspect ratio is 0.87 or higher. 14-sided diamond abrasive grains. <2> The aforementioned diamond abrasive grains are used in a pad conditioner for chemical mechanical planarization (CMP) processes. <1> Diamond abrasive grains as described above. <3> The aforementioned 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. <1> Diamond abrasive grains as described above. <4> The diamond abrasive grains have a particle size distribution width of 15 μm or less. <1> Diamond abrasive grains as described above. <5> The internal impurities in the diamond abrasive grains are 300 ppm or less. <1> Diamond abrasive grains as described above. <6> The surface impurities of the diamond abrasive grains are 20 ppb or less. <1> Diamond abrasive grains as described above. <7> (a) A step of providing a cell equipped with graphite and a catalyst, (b) The step of applying pressure and heat to the cell, (c) A step of recovering the diamond particles synthesized from the cell, (d) The step of classifying the diamond particles, (e) A step of removing surface impurities from the diamond particles, A method for manufacturing diamond abrasive particles containing diamond abrasive particles. <8> The cell in step (a) above comprises a material formed by mixing graphite powder and catalyst powder. <7> A method for manufacturing diamond abrasive grains as described above. <9> The cell in step (a) above includes a graphite disk. <7> A method for manufacturing diamond abrasive grains as described above. <10> The catalyst comprises one or more elements selected from the group consisting of iron, nickel, chromium, cobalt, manganese, copper, zinc, and mixtures thereof. <7> A method for manufacturing diamond abrasive grains as described above. <11> The above step (b) is carried out under pressure conditions of 6.15 to 6.65 GPa. <7> A method for manufacturing diamond abrasive grains as described above. <12> The above step (b) is carried out under temperature conditions of 1,555 to 1,610 K. <7> A method for manufacturing diamond abrasive grains as described above. <13> The aforementioned step (b) is performed using a belt-type device. <7> A method for manufacturing diamond abrasive grains as described above.

Claims

1. Synthesized by a high-pressure, high-temperature process, A 14-sided diamond abrasive grain having a shape value of 0.87 or higher, wherein the shape value is the ratio of the length of the minor axis to the length of the major axis of the abrasive grain. 14-sided diamond abrasive grains.

2. The diamond abrasive grains are used in a pad conditioner for a chemical mechanical planarization (CMP) process, as described in claim 1.

3. The diamond abrasive grain 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 grain size distribution width of the diamond abrasive grains is 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 grain according to claim 1, wherein the surface impurities of the diamond abrasive grain are 20 ppb or less.

7. (a) A step of providing a cell equipped with graphite and a catalyst, (b) A step of applying a pressure of 6.15 GPa or more and 6.65 GPa or less and a temperature of 1,555 K or more and 1,610 K or less to the cell, (c) A step of recovering the diamond particles synthesized from the cell, (d) A step of classifying the diamond particles, (e) A step of removing surface impurities from the diamond particles, A method for manufacturing 14-sided diamond abrasive grains, wherein the shape value of the diamond abrasive grain is 0.87 or more, and the shape value is the ratio of the length of the minor axis to the length of the major axis of the abrasive grain.

8. The method for producing diamond abrasive grains according to claim 7, wherein the cell in step (a) comprises 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) includes a graphite disc.

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 producing diamond abrasive grains according to claim 7, wherein step (b) is performed using a belt-type device.

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