JP7767449B2 - Diamond disc and its manufacturing method - Google Patents

Description

The present invention relates to a diamond disc and a method for manufacturing the same.

Generally, the CMP (Chemical Mechanical Polishing) process is a chemical-mechanical polishing process that simultaneously uses polishing removal and the dissolving action of chemical solutions to achieve flatness on semiconductor wafers.

The CMP polishing process involves supplying a slurry containing abrasive particles and chemicals onto the polishing pad while the polishing pad and wafer are pressed against each other and moving relative to each other. During this process, the numerous foam pores on the surface of the polyurethane polishing pad serve to retain new slurry, achieving consistent polishing efficiency and uniform polishing across the entire wafer surface.

However, because pressure and relative velocity are applied during polishing, the surface of the polishing pad deforms unevenly over the course of processing, and the pores on the polishing pad become clogged with polishing residue, preventing the polishing pad from fulfilling its function. This makes it impossible to achieve global planarization across the entire wafer surface or uniform polishing between wafers during the entire processing time.

To solve this problem of uneven deformation and clogged pores in CMP polishing pads, CMP pad conditioning is performed by using a CMP pad conditioner to finely polish the surface of the polishing pad, thereby creating new micropores.

CMP pad conditioning can be performed simultaneously with the main CMP process to increase productivity. This is known as in-situ conditioning.

The polishing solution used in CMP contains abrasive particles such as silica, alumina, and ceria, and CMP processes are broadly divided into oxide CMP and metal CMP depending on the type of polishing solution used. The polishing solution for oxide CMP used in the former has a pH value of mainly 10-12, while the polishing solution for metal CMP used in the latter has a pH of 4 or less and uses an acidic solution.

Conventional CMP pad conditioners typically include electrodeposited CMP pad conditioners manufactured using an electrodeposition method and fused-type CMP pad conditioners, which are made by melting metal powder at high temperatures. These CMP pad conditioners primarily use granular diamond particles as the abrasive. The diamond particles are fixed in place by a metal matrix formed by electrodeposition or fusion.

Diamond is known to be the hardest substance on Earth, and due to these properties, diamond tools made from artificial diamonds are produced and used.

In conventional CMP processes, diamonds are used in CMP pad conditioners along with slurry for wafer polishing. When highly corrosive slurry is used, additives in the slurry react with the carbon in the diamond, accelerating diamond wear and shortening the lifespan of the diamond disk.

Korean Patent Publication No. 10-2012-0058303

The present invention aims to provide a diamond disc with improved wear resistance and high grinding performance, as well as a manufacturing method thereof.

According to one aspect of the present invention, a diamond disk can be provided, comprising: a shank base; a bonding layer formed on the surface of the shank base; and a plurality of boron-doped diamonds (BDDs) arranged so as to be exposed to the bonding layer, wherein at least some of the plurality of boron-doped diamonds are arranged on the bonding layer with the uppermost surface thereof meeting the long axis of the boron-doped diamond and tilting downward from the upper end of the long axis.

Furthermore, the long axis of the boron-doped diamond may be oriented at an angle greater than 50° and less than 90° relative to the shank base, and the boron-doped diamond may be positioned on the bonding layer.

In addition, the wetting angle where the surface of the bonding layer meets the surface of the boron-doped diamond can be maintained between 0° and 60°.

Furthermore, the ratio of the thickness of the bonding layer to the average diameter of the boron-doped diamond can be in the range of 30% to 65%.

Furthermore, the amount of boron doped into the boron-doped diamond can be in the range of 1 ppm to 2000 ppm.

Furthermore, the magnetic susceptibility per unit volume of the boron-doped diamond can be in the range of 20 to 800 per unit volume.

In addition, the ratio of the density of the boron-doped diamond to the density of the bonding layer can be maintained in the range of 0.4 to 0.6.

In addition, the boron-doped diamond is an octahedron diamond, and the lower end of the boron-doped diamond can be in point or line contact with the surface of the shank base or can be spaced a predetermined distance apart when the boron-doped diamond is erected on top of the bonding layer.

In addition, the pad polishing characteristics (PCR: Pad Cut Rate) of the boron-doped diamond were measured in a PCR test device. When the CMP pad conditioner made of the boron-doped diamond rotated at 100 rpm to 120 rpm and the polishing pad rotated at 80 rpm to 95 rpm, it took 13 hours or more for the PCR to decrease to the range of 2 to 10 μm/hr due to pad conditioning when the CMP pad conditioner made of the boron-doped diamond pressed the polishing pad with a pressure of 4.5 to 9 lbf.

According to another aspect of the present invention, a method for manufacturing a diamond disk can be provided, including: a bonding material application step of applying a bonding material to the surface of a shank base; a pre-sintering step of heating the bonding material applied to the surface of the shank base within a first temperature range to form a bonding layer in the form of a pre-sintered body; a diamond providing step of providing a plurality of boron-doped diamonds (BDDs) on the surface of the pre-sintered body; and a heat-treating step of heat-treating at least some of the plurality of boron-doped diamonds within a second temperature range so that the uppermost surface of the boron-doped diamonds is positioned in the bonding layer in an orientation that is inclined downward from the upper end of the long axis while meeting the long axis of the boron-doped diamonds.

Furthermore, during the heat treatment step, the long axis of the boron-doped diamond may be positioned so as to be exposed to the bonding layer at an angle greater than 50° and less than 90° relative to the shank base.

Furthermore, the first temperature range in the preliminary sintering step may be 600°C to 900°C, and the second temperature range in the heat treatment step may be 1000°C to 1300°C.

Furthermore, during the heat treatment step, the wetting angle where the surface of the bonding layer meets the surface of the boron-doped diamond can be maintained between 0° and 60°.

Furthermore, during the heat treatment step, the thickness ratio of the bonding layer after heat treatment to the average diameter of the boron-doped diamond may be in the range of 30% to 65%.

According to an embodiment of the present invention, the octahedral boron-doped diamond (BDD) has the advantage of achieving excellent wear resistance and high grinding performance.

Furthermore, according to an embodiment of the present invention, the boron-doped diamond (BDD) is octahedral, and the self-standing ratio of the boron-doped diamond is above a certain level, which has the advantage of improving wear resistance and grinding performance.

FIG. 1 is a diagram showing a diamond disk according to an embodiment of the present invention, in which boron-doped diamond (BDD) is temporarily attached onto a bonding layer in the form of a pre-sintered body. FIG. 2 is a diagram showing a state in which boron-doped diamond (BDD) stands up on the bonding layer after heat treatment in a diamond disk according to one embodiment of the present invention. FIG. 3 is a diagram showing a state in which boron-doped diamond (BDD) is wetting onto the bonding layer after heat treatment in a diamond disk according to one embodiment of the present invention. FIG. 4 is a photograph comparing the wear state of a diamond disk according to an embodiment of the present invention with that of a general diamond. FIG. 5 is a photograph comparing the wear state of a diamond disk according to an embodiment of the present invention with that of a general diamond. FIG. 6 is a magnified photograph comparing a diamond disk to which a boron-doped diamond (BDD) according to one embodiment of the present invention is applied and a diamond disk to which a general octahedral diamond not doped with boron is applied. FIG. 7 is a graph showing PCR tests of diamond disks to which boron-doped diamond (BDD) and general octahedral diamond are applied according to one embodiment of the present invention. FIG. 8 is a graph showing the weight loss rate due to heat treatment in a boron-doped diamond (BDD) according to an embodiment of the present invention and a regular diamond. FIG. 9 is a block diagram illustrating a method for manufacturing a diamond disk according to one embodiment of the present invention.

Specific embodiments for realizing the technical concept of the present invention will be described in detail below with reference to the accompanying drawings.

In addition, in describing the present invention, if it is determined that a specific description of related publicly known configurations or functions may obscure the gist of the present invention, such detailed description will be omitted.

Furthermore, when a component is referred to as being "coupled," "supported," "connected," "supplied," "transmitted," or "in contact" with another component, it should be understood that the component may be directly coupled, supported, connected, supplied, transmitted, or in contact with the other component, but there may also be other components in between.

The terms used in this specification are merely used to describe specific embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise.

Please note that in this specification, expressions such as upper, lower, and side are explained based on the illustrations in the drawings, and it should be made clear that they may be expressed differently if the orientation of the object in question changes. For the same reason, some components in the accompanying drawings are exaggerated, omitted, or shown schematically, and the size of each component does not fully reflect its actual size.

Furthermore, terms including ordinal numbers such as first, second, etc. may be used to describe various components, but the corresponding components are not limited by such terms. These terms are used only to distinguish one component from another.

As used herein, the meaning of "comprise" embodies certain properties, regions, constants, steps, operations, elements and/or components, and does not exclude the presence or addition of other certain properties, regions, constants, steps, operations, elements, components and/or groups.

First, when comparing the chemical composition of diamond between a regular diamond and the boron-doped diamond (BDD) of the present invention, the wear resistance of the boron-doped diamond (BDD) is superior to that of regular diamond in highly corrosive environments (e.g., CMP, oxide CMP processes), but in less corrosive general environments, there is no significant difference in the wear resistance of regular diamond and boron-doped diamond (BDD).

The electrodeposition CMP diamond disc manufacturing method uses a nickel electroplating bonding layer to support the non-conductive diamond. However, boron-doped diamond (BDD), which conducts electricity, cannot be used in the electrodeposition process using conventional methods because the nickel electroplating layer covers the surface of the boron-doped diamond during electroplating. Therefore, boron-doped diamond (BDD) can be used to manufacture diamond discs using the fusion and sintering methods.

In addition, when processing general iron (Fe)-based metals, diamond has an affinity with the iron-based metal, making metal processing difficult. When slurry is supplied to the polishing pad during CMP pad conditioning, the iron (Fe) component in the slurry can react with the carbon in the diamond on the diamond disk, accelerating the wear of the diamond. Ultimately, the diamond wears faster and its lifespan is shortened. However, the boron-doped diamond (BDD) according to the present invention inhibits the oxidation reaction of carbon (C + O ₂ → CO ₂ ) (acts as a blocking layer), thereby improving the stability of the diamond disk.

The manufacturing differences between the boron-doped diamond (BDD) of this invention, regular diamond, and conventional boron nitride (CBN: cubic boron nitride) are shown in Table 1 below.

In the case of the boron-doped diamond according to the present invention, Fe, Ni alloy and boron (Boron: Pure boron or boron carbide) are catalysts, and boron can substitute for carbon in diamond synthesis or can penetrate into the diamond structure. This boron-doped diamond can suppress the reaction between external iron (Fe) and carbon in the diamond, and can provide all the characteristics of abrasion-resistant diamond.

Regular diamonds, on the other hand, contain no boron, although an Fe-Ni alloy acts as a catalyst for carbon. Cubic boron nitride (CBN) contains a relatively large amount of boron, with a carbon to boron ratio of 1:1, so it does not react with iron (Fe). However, it has significantly lower strength than boron-doped diamonds and can be difficult to shape.

In this embodiment, among the diamonds used in the diamond disk, boron-doped diamond (BDD) can be used at 5 vol% or more of the total diamond depending on the intended use. The octahedral structure ratio in the boron-doped diamond (BDD) can be 50% or more. The proportion of self-standing boron-doped diamond (BDD) in the bonding layer can be 60% or more of the total boron-doped diamond (BDD).

The ratio can be determined by observing the entire diamond in a certain area and determining the percentage of diamonds that meet the above criteria.

The specific configuration of a diamond disc according to one embodiment of the present invention will now be described with reference to Figures 1 to 8.

Referring to Figures 1 to 6, a diamond disk according to the present invention can be applied to a CMP pad conditioner to finely polish the surface of a polishing pad. Such a diamond disk can include a shank base 100, a bonding layer 200, and a plurality of boron-doped diamonds (BDDs) 300.

Specifically, the shank base 100 is a backing plate for the disk, and a bonding layer 200 can be formed on the surface of the shank base 100. The shank base 100 corresponds to a typical shank base 100 used as a backing plate for a disk, so a detailed description thereof will be omitted.

The bonding layer 200 may be made of a bonding material containing 60 wt% or more Ni and other elements such as Cr and Si. The bonding material may be applied to the surface of the shank base 100, and then dried and pre-sintered to form a solid-phase pre-sintered body. An adhesive may be applied to the upper surface of the pre-sintered body to temporarily bond the boron-doped diamond 300. The boron-doped diamond 300 may be temporarily bonded to the upper surface of the pre-sintered body to which the adhesive has been applied using a drilling jig.

The pre-sintered body can be formed into a bonding layer 200 through a heat treatment process together with the boron-doped diamond 300. The bonding layer 200 can change into a liquid state during the high-temperature heat treatment process, and the boron-doped diamond 300 can be arranged in an upright state on top of the bonding layer 200. The bonding layer 200 with the boron-doped diamond 300 arranged in an upright state can be cooled and dried.

The density of the bonding layer 200 can be in the range of 6 g/ ^cm to 8.3 g/ ^cm . The density of the boron-doped diamond 300 can be in the range of 3.5 g/ ^cm to 3.6 g/ ^cm . In this embodiment, the density of the bonding layer 200 is 7.6 g/ ^cm and the density of the boron-doped diamond 300 is ^3.54 g/cm.

The ratio of the density of the boron-doped diamond 300 to the density of the bonding layer 200 can be in the range of 0.4 to 0.6. If the ratio of the density of the boron-doped diamond 300 to the density of the bonding layer 200 is higher than 0.6, the buoyancy of the boron-doped diamond 300 due to the density difference between the bonding layer 200 and the boron-doped diamond 300 is too low, and the boron-doped diamond 300 may be immersed inside the bonding layer 200. If the ratio of the density of the boron-doped diamond 300 to the density of the bonding layer 200 is lower than 0.4, the buoyancy of the boron-doped diamond 300 due to the density difference between the bonding layer 200 and the boron-doped diamond 300 is too high, and the boron-doped diamond 300 may float on the top surface of the bonding layer 200 and tilt horizontally.

The boron-doped diamond 300 can be constructed by incorporating Fe, Ni alloy and boron (Boron: Pure boron or boron carbide) as a catalyst into carbon. As an example, the boron-doped diamond 300 may incorporate Fe, Ni alloy and 1 ppm to 2000 ppm of boron (Boron: Pure boron or boron carbide) into the carbon. In the diamond structure, boron can substitute for carbon or be inserted into the diamond structure. This boron-doped diamond 300 can provide high wear resistance without reacting with external iron (Fe).

The TI (Toughness Index) of the boron-doped diamond 300 can be 20 to 50, and the TTI (Temperature Toughness Index) can be 14 to 45. The magnetic susceptibility (MS) per unit volume of the boron-doped diamond 300 can be 20 to 800, and more preferably 30 to 500.

Fe, Ni, and other metals used as catalysts in the synthesis of boron-doped diamond 300 are contained within the diamond as foreign matter. Generally, the amount of foreign matter increases proportionally as the amount of boron doped increases. If the MS value is less than 20, the amount of boron doped is too small, and the effect of boron in improving corrosion resistance may be reduced. If the MS value exceeds 800, the amount of boron doped is high, but the physical properties of the diamond may be reduced due to excessive contamination with ferromagnetic metal foreign matter such as Fe and Ni, and problems may occur such as cracking of diamond particles during CMP pad conditioning. The greater the amount of metal foreign matter within boron-doped diamond 300, the lower the TI and TTI values, which can also be determined through MS measurement. Diamond toughness (TI, TTI, or MS) must be high enough to withstand prolonged use under pressure under CMP conditions.

The boron-doped diamond 300 can be an octahedron diamond. Diamonds can be produced in an octahedron shape depending on the synthesis conditions. Octahedron diamonds have sharp edges, and in octahedron diamonds, the angle between the line connecting the vertex and the center and the face is 35° to 45°.

Such boron-doped diamonds (BDD) 300 may be provided in multiple pieces and arranged so as to be exposed to the bonding layer 200. At least some of the multiple boron-doped diamonds 300 may be arranged on the bonding layer 200 with their major axes L at an angle C of more than 50° and not more than 90° relative to the shank base 100.

In this embodiment, the imaginary line connecting the two most distant vertices of the diamond 300 that face each other can be defined as an "axis," and the longest axis of these "axes" can be defined as the "major axis (L)." Furthermore, a "vertex" can be defined as the point where adjacent corners meet. If adjacent corners do not meet as a "point" (for example, if the part corresponding to the vertex is rounded), the imaginary point where the extended corners meet when the adjacent corners are extended can be defined as the vertex. A boron-doped diamond whose major axis is 50° or greater can be defined as self-standing.

The term "self-standing" can be understood to mean that the boron-doped diamond 300 is positioned independently on the bonding layer 200 with the long axis L of the boron-doped diamond 300 at an angle C of more than 50° and less than 90° relative to the shank base 100. When the boron-doped diamond 300 is self-standing on the bonding layer 200, the apex of the lower end of the long axis direction of the boron-doped diamond 300 can be in point or line contact with the surface of the shank base 100 or can be spaced a predetermined distance apart.

When the long axis L of the boron-doped diamond 300 is at an angle of 35° to the shank base 100, the boron-doped diamond 300 will come into surface contact with the workpiece (polishing pad), which may significantly reduce the polishing performance of the boron-doped diamond 300 against the workpiece. The closer the long axis L of the boron-doped diamond 300 is to 90° to the shank base 100, the more the boron-doped diamond 300 will come into point contact with the workpiece (polishing pad), which can significantly improve the polishing performance of the boron-doped diamond 300 against the workpiece.

In order for the long axis L of the boron-doped diamond 300 to be positioned on the bonding layer 200 at an angle C greater than 50° and less than 90° relative to the shank base 100, the wetting angle θ where the surface of the boron-doped diamond 300 meets the surface of the bonding layer 200 must be less than 90°, and preferably the components of the bonding layer 200 must be configured so that it is less than 60°.

Referring to FIG. 3 and Equation 1 below, the wetting angle θ can be determined by the vertical component forces of the upward force _FV , the downward force _FD , and the lateral force _FL .

[Formula 1]
F _V =F _D +F _L cosθ
When the wetting angle θ is greater than 90°, the vertical component of the force F _L is upward, so the boron-doped diamond 300 can float further, and when the wetting angle θ is less than 90°, the direction of the vertical component of the force F _L directed laterally can change to a downward side direction, so the boron-doped diamond 300 can receive a downward force.

For example, if the wetting angle θ is greater than 90°, the buoyancy of the boron-doped diamond 300 prevents the bonding layer 200 from properly supporting the boron-doped diamond 300, increasing the risk of the boron-doped diamond 300 falling off. Furthermore, chip pockets for the discharge of debris generated during polishing may not be formed in the bonding layer 200, preventing proper discharge of the debris and significantly reducing polishing performance. Preferably, for an octahedral boron-doped diamond 300, the wetting angle θ is less than 60°, allowing the boron-doped diamond 300 to make point or line contact with the workpiece (polishing pad), effectively forming chip pockets and significantly improving the polishing performance of the boron-doped diamond 300 on the workpiece.

However, even if the wetting angle between the boron-doped diamond 300 and the bonding layer 200 is less than 60°, if the bonding layer 200 is too thick, the exposed height of the boron-doped diamond 300 in the bonding layer 200 will be low, and the boron-doped diamond 300 will float due to buoyancy, allowing it to come into surface contact with the workpiece. Furthermore, if the chip pocket for discharging residue generated during polishing with the boron-doped diamond 300 is formed shallowly in the bonding layer 200, the residue generated during polishing may not be discharged smoothly.

Furthermore, if the wetting angle of the boron-doped diamond (BDD) 300 is less than 60°, the boron-doped diamond 300 will be driven deeper into the bonding layer 200 due to surface tension, which may reduce the height at which the boron-doped diamond 300 protrudes from the bonding layer 200. Therefore, the thickness of the bonding layer 200 must be strictly controlled to ensure an outlet for the residue generated during polishing of the diamond disk.

Furthermore, if the bonding layer 200 is thinner than the appropriate thickness, self-standing may occur due to buoyancy (difference in density between the boron-doped diamond and the bonding layer) and wetting. In this case, a chip pocket is successfully formed in the bonding layer 200, but if the bonding layer 200 is too thin, the boron-doped diamond 300 comes into contact with the shank base 100, and surface tension causes the boron-doped diamond 300 to be subjected to additional downward force. At this time, the boron-doped diamond 300 tilts and becomes horizontal, reducing the exposed height of the boron-doped diamond 300 in the bonding layer 200 and potentially causing surface contact between the boron-doped diamond 300 and the workpiece. For example, if the diamond is placed on its side on the bonding layer 200 in an orientation where the angle between the long axis of the boron-doped diamond 300 and the shank base 100 is an angle C of approximately 35° to 45°, the self-standing ratio of the boron-doped diamond 300 may be low.

The thickness of the bonding layer 200 according to the present invention has a certain ratio to the average diamond grain size (diameter). For example, the ratio of the thickness of the bonding layer 200 to the average diameter of the boron-doped diamond 300 according to the present invention can range from 30% to 65%. Table 2 shows the diamond ratio (self-standing ratio) and PCR (pad cut rate) for each height of the bonding layer 200. Diamond grain size has a certain range depending on the mesh size, and the average diamond size follows the ANSI standard. For example, the diamonds used in Table 2 were #80 to #100, with an average size of 150 μm and a size range of 127 to 181 μm. Diamonds were deposited on a disk with a diameter of approximately 4 inches at a density of 400 diamonds/ ^cm² . The number of diamonds deposited per unit area can vary depending on the average size of the diamonds.

Referring to Table 2, when the bonding layer thickness is 68 μm, 79 μm, and 94 μm, the diamond exposure height is relatively high compared to the bonding layer thickness, the diamond ratio with a good angle, for example, the self-standing ratio, is highest, and the PCR is also highest. When the bonding layer thickness is 106 μm, the diamond exposure height is also relatively low compared to the bonding layer thickness, the diamond ratio with a good angle (self-standing ratio) is low, and the PCR is also low. When the bonding layer thickness is 52 μm, the diamond exposure height is relatively high compared to the bonding layer thickness, but the diamond ratio with a good angle (self-standing ratio) is slightly lower and the PCR is also slightly reduced.

In other words, if the thickness ratio of the bonding layer 200 to the average diameter of the boron-doped diamond 300 is 70% or more, the PCR becomes very low, so the thickness ratio of the bonding layer 200 to the average diameter of the boron-doped diamond 300 must be controlled to less than 70%. Furthermore, if the thickness of the bonding layer 200 is too thin, even if the PCR value is maintained to a certain extent, there is a risk of the diamond falling off, so the thickness of the bonding layer 200 must be at least 30% or more of the average size of the diamond. Therefore, the thickness ratio of the bonding layer 200 to the average diameter of the boron-doped diamond 300 is preferably in the range of 30% to 65%.

Figure 6 shows cross-sectional photographs of boron-doped octahedral diamond 300 and regular octahedral diamond after heat treatment. Even though regular diamonds that are not doped with boron have an octahedron shape, when a PCR test is carried out for 15 minutes in a PCR test device, the PCR value of the regular diamond is lower than the PCR value of boron-doped diamond (BDD) 300 under the same conditions. Blocky-type diamonds, i.e., cubic-octahedral shaped diamonds, whether doped with boron or not, show very low PCR values in PCR tests under the same conditions as boron-doped diamond disks.

Referring to Figure 7, to measure the long-term PCR (Pad Cut Rate) of disks fabricated from boron-doped diamond 300 and general octahedral diamond, a PCR tester, polishing pad, CMP pad conditioner, and slurry are prepared. As an example, a CTS CMP polisher can be used as the PCR tester, a 20" diameter IC1010 (Dupont) product can be used as the polishing pad, and a W7000 (Cabot microelectronics) product can be used as the slurry. The CMP pad conditioner can be equipped with a 4" diameter boron-doped octahedral diamond 300 and a general octahedral diamond.

After preparing the PCR test device, polishing pad, CMP pad conditioner, and slurry, the polishing pad is rotated at 80-95 rpm, and the CMP pad conditioner is rotated at 100-120 rpm. The time used for the CMP pad conditioner's boron-doped diamond 300 or general octahedral diamond to pressurize the polishing pad at 4-9 lbf is measured until the PCR falls below the minimum PCR value for pad conditioning. If the PCR value falls below the set value, the CMP pad conditioner is deemed to be insufficient in its function. The CMP pad conditioner can polish the polishing pad by moving back and forth from the center to the edge of the polishing pad 18-20 times per minute, providing 300 ml of slurry to the polishing pad per minute.

Long-term PCR testing confirmed that, for example, a CMP pad conditioner equipped with a general octahedral diamond required 8 hours to reach a PCR of 10 μm/hr, while a CMP pad conditioner equipped with a boron-doped diamond 300 required 13 hours to reach a PCR of 10 μm/hr. In the PCR tests described herein, it took 13 hours for the CMP pad conditioner to reach a PCR of 10 μm/hr, but times longer than 13 hours are also within the scope of the present invention. Since the longer it takes for a CMP pad conditioner to reach a PCR of 10 μm/hr, the more advantageous it is. Therefore, there is no need to specify an upper limit for the time required for a CMP pad conditioner to reach a PCR of 10 μm/hr. However, the time required for a CMP pad conditioner to reach a PCR of 10 μm/hr may be 100 hours. Furthermore, even when the set value was set to, for example, 5 μm/hr or 2 μm/hr, it was confirmed that boron-doped diamond 300 maintained its pad polishing characteristics for 30% or longer than ordinary octahedral diamond.

Figures 4 and 5 are SEM photographs of individual diamonds on a disk observed over time under the above experimental conditions. The comparative example is a regular octahedral diamond, which has sharp edges before use, but after 10 and 15 hours, the edges are observed to have almost completely worn away. On the other hand, the boron-doped octahedral diamond used in the example shows that the edges are relatively unworn even after 10 and 26 hours of use.

Referring to Figure 8, the weight change can be confirmed by treating only diamond in an air atmosphere at 750°C for 3 hours. While the weight of ordinary diamonds decreased by 24.8%, the weight of the boron-doped diamond (BDD) 300 according to the present invention decreased by 2.5%. For example, boron-doped diamonds showed a significantly lower weight change rate than ordinary diamonds. This confirms that boron doping inhibits diamonds from reacting with oxygen in the air, making them highly chemically stable.

Therefore, the diamond disc according to the present invention can provide all the wear-resistant characteristics of diamond while retaining the same characteristics as boron nitride (CBN), which does not react with iron (Fe), thereby improving the lifespan of the diamond disc.

Below, with reference to Figure 9, a method for manufacturing a diamond disk according to one embodiment of the present invention will be described.

Referring to FIG. 9, a method for manufacturing a diamond disk according to one embodiment of the present invention may include a bonding material application step S100, a preliminary sintering step S200, a diamond provision step S300, and a heat treatment step S400.

In the bonding material application step S100, a bonding material can be applied to the surface of the shank base. The bonding material can contain 60 wt% or more of Ni and other elements such as Cr and Si.

In the preliminary sintering step S200, the bonding material applied to the surface of the shank base is heated and dried in a first temperature range to form a solid-phase preliminary sintered body. The first temperature range may be 600°C to 900°C. In the preliminary sintering step S200, the thickness ratio of the bonding layer after the final heat treatment to the average diameter of the boron-doped diamond may be in the range of 30% to 65%.

In the diamond providing step S300, a plurality of boron-doped diamonds (BDDs) can be provided on the surface of the pre-sintered body. At this time, the plurality of boron-doped diamonds can be temporarily bonded to the pre-sintered body with an adhesive using a drilling jig.

In the heat treatment step S400, the plurality of boron-doped diamonds may be heat-treated in a second temperature range so that they are arranged in an upright state and exposed to the pre-sintered body. At least some of the plurality of boron-doped diamonds may be self-standing with their major axes L at an angle C of more than 60° and less than 90° relative to the shank base. In this case, the second temperature range may be between 1000°C and 1300°C.

In the heat treatment step S400, the solid-phase pre-sintered body changes phase to a liquid bonding layer. As a result, a portion (approximately 50 vol%) of the individual boron-doped diamonds can be exposed to the upper surface of the bonding layer 200 due to buoyancy caused by the density difference, and the remaining portion (approximately 50 vol%) of the individual boron-doped diamonds can sink below the surface of the bonding layer.

At this time, it is most stable for the octahedral boron-doped diamond to have its lower apex pointing downward. This may vary depending on the high-temperature heat treatment temperature, the viscosity of the bonding layer, and the heat treatment time, but if maintained under these conditions for a long period of time, the boron-doped diamond may rotate, resulting in a self-standing phenomenon.

In the heat treatment step S400, the wetting angle where the surface of the pre-sintered body meets the surface of the boron-doped diamond can be maintained between 0° and 60°. For octahedral boron-doped diamond, the wetting angle less than 60° improves chip pocket formation, and since the boron-doped diamond makes point or line contact with the workpiece (polishing pad), the polishing performance of the boron-doped diamond on the workpiece can be significantly improved.

As described above, the present invention can achieve excellent wear resistance and high grinding performance through the octahedral boron-doped diamond, and has the excellent advantage of improving wear resistance and grinding performance because the proportion of self-standing boron-doped diamond is above a certain level.

Although the embodiments of the present invention have been described above using specific examples, these are merely examples, and the present invention is not limited thereto and should be construed as having the broadest scope in accordance with the technical ideas disclosed herein. Those skilled in the art may combine/substitute the disclosed examples to implement patterns of shapes not shown, but this would not depart from the scope of the present invention. Furthermore, those skilled in the art may easily modify or change the disclosed examples based on this specification, and it is clear that such modifications or changes also fall within the scope of the present invention.

Claims (10)

1. A diamond disc for use in a chemical mechanical polishing pad conditioner, comprising:
Shank base;
a bonding layer formed on a surface of the shank base; and a plurality of boron-doped diamonds (BDDs) arranged so as to be exposed to the bonding layer,
At least some of the boron-doped diamonds are arranged on the bonding layer in such a manner that the uppermost surfaces intersecting with the long axes of the boron-doped diamonds are inclined downward from the upper ends of the long axes;
The boron-doped diamond is placed on the bonding layer in an orientation such that the long axis of the boron-doped diamond forms an angle of more than 50° and not more than 90° with respect to the shank base;
a wetting angle between the surface of the bonding layer and each surface of the boron-doped diamond is maintained between 0° and 60° ;
The wetting angle is determined by the following equation:
[Formula 1]
F _V =F _D +F _L ・cosθ

wherein, at the contact point between the surface of the bonding layer and the surface of the boron-doped diamond, F _V is an upward force acting due to the interfacial energy between the boron-doped diamond and air, F _D is a downward force acting due to the interfacial energy between the boron-doped diamond and the bonding layer, F _L is a force acting on the contact point of the bonding layer due to the interfacial energy between the bonding layer and air, and θ is a wetting angle , diamond disk. A diamond disk as described in claim 1, characterized in that the ratio of the thickness of the bonding layer to the average diameter of the boron-doped diamond is in the range of 30% to 65%. The diamond disk described in claim 1, characterized in that the amount of boron doped into the boron-doped diamond is in the range of 1 ppm to 2000 ppm. The diamond disk described in claim 1, characterized in that the magnetic susceptibility per unit volume of the boron-doped diamond is in the range of 20 to 800 per unit volume. A diamond disk as described in claim 1, characterized in that the ratio of the density of the boron-doped diamond to the density of the bonding layer is maintained in the range of 0.4 to 0.6. The boron-doped diamond is an octahedron diamond,
The diamond disk of claim 3, wherein the lower end of the boron-doped diamond makes point or line contact with the surface of the shank base or is spaced a predetermined distance from the surface when the boron-doped diamond is raised on top of the bonding layer. The diamond disk described in claim 1, characterized in that the pad cut rate (PCR) of the boron-doped diamond is such that, when a CMP pad conditioner made of the boron-doped diamond is rotated at 100 rpm to 120 rpm and a polishing pad is rotated at 80 rpm to 95 rpm in a PCR testing device, it takes 13 hours or more for the PCR to decrease to the range of 2 to 10 μm/hr due to pad conditioning when the CMP pad conditioner made of the boron-doped diamond presses the polishing pad at a pressure of 4 to 9 lbf. A method for manufacturing a diamond disc, comprising:
The diamond disc is used in a chemical mechanical polishing pad conditioner;
The manufacturing method includes:
a bonding material application step of applying a bonding material to a surface of the shank base;
a pre-sintering step of heating the bonding material applied to the surface of the shank base within a first temperature range to form a bonding layer in the form of a pre-sintered body;
a diamond providing step of providing a plurality of boron-doped diamonds (BDDs) on the surface of the pre-sintered body; and a heat treatment step of carrying out a heat treatment in a second temperature range, wherein at least some of the plurality of boron-doped diamonds are placed on the bonding layer with their uppermost surfaces intersecting with the long axes of the boron-doped diamonds inclined downward from the upper ends of the long axes,
In the heat treatment step, the boron-doped diamond is placed on the bonding layer in an exposed state in an orientation such that the long axis of the boron-doped diamond has an angle of more than 50° and not more than 90° with respect to the shank base;
In the heat treatment step, a wetting angle between a surface of the bonding layer and each surface of the boron-doped diamond is maintained between 0° and 60° ,
The wetting angle is determined by the following equation:
[Formula 1]
F _V =F _D +F _L ・cosθ

wherein, at the contact point between the surface of the bonding layer and the surface of the boron-doped diamond, F _V is an upward force acting due to interfacial energy between the boron-doped diamond and air, F _D is a downward force acting due to the interfacial energy between the boron-doped diamond and the bonding layer, F _L is a force acting on the contact point of the bonding layer due to the interfacial energy between the bonding layer and air, and θ is a wetting angle . The method for manufacturing a diamond disk described in claim 8, characterized in that the first temperature range in the preliminary sintering step is 600°C to 900°C, and the second temperature range in the heat treatment step is 1000°C to 1300°C. The method for manufacturing a diamond disk described in claim 8, characterized in that, during the heat treatment step, the thickness ratio of the bonding layer after heat treatment to the average diameter of the boron-doped diamond is in the range of 30% to 65%.