Granular abrasive particles having tip basal part

Abstract

Provided are granular abrasive particles having a tip basal part, whereby the life of the particles is extended, a stable PCR value is quickly reached, and the stable PCR value is maintained for as long as possible to improve physical properties and thereby effectively perform precise processing including conditioning and dressing. The abrasive particles comprise a cutting tip and the tip basal part and are polyhedral and granular, and the cutting tip protrudes from the tip basal part, is formed by removing a part of the polyhedron, and is located on the inside of the polyhedron.

Description

Abrasive particles in the form of granules with a tip base

[0001] The present invention relates to abrasive particles, and more particularly, to abrasive particles for smoothly and effectively performing CMP conditioner, dressing, and other operations using granular abrasive particles having a cutting tip protruding from a tip base.

[0002] Abrasive particles are particles that smooth the surface of a workpiece by rubbing or impacting it, and are utilized in various applications. For example, chemical mechanical planarization (CMP) technology flattens a wafer by supplying slurry to a polishing pad attached to a platen and allowing the relative motion of the platen and carrier. However, since pressure and relative velocity are applied during polishing, the polishing pad surface becomes unevenly deformed over time, and the pores in the polishing pad become clogged with polishing residue, preventing the polishing pad from performing its intended function. To address this uneven deformation and pore clogging, a CMP pad conditioner is used. The CMP pad conditioner polishes the surface of the polishing pad, correcting any deformation and forming new micropores.

[0003] CMP pad conditioners utilize various methods, such as the individual cutting tip method of Korean Patent Nos. 10-1926449 and 10-2013383, and the CVD diamond method of Korean Patent No. 10-1178281 (hereinafter referred to as the CVD method). However, the conventional individual cutting tip method using diamond particles has a polyhedral particle shape, so as the polishing of the special polishing pad progresses, the contact area with the polishing pad increases due to the wear of the cutting tip. When the cutting tip wears, the pressure per unit area of ​​the polishing pad decreases, and the PCR (Pad Cutting Rate) value drops sharply. Attempts to maintain the PCR value by appropriately adjusting the size of the abrasive particles are being made, but this is not a fundamental solution. To solve the above problem, the CVD method was adopted, but there is also a lifespan limit depending on the coating thickness. Additionally, for CVD-type conditioners with flat cutting tips, it takes a relatively long time to reach a stable PCR value in the polishing pad breaking process at the beginning of the operation.

[0004] Meanwhile, there is a demand for a method to effectively perform precision processing including conditioning and dressing, such as extending the life of abrasive particles and maintaining polishing ability for as long as possible, not only in CMP pad conditioners but also in precision polishing processing such as dressing.

[0005] The problem to be solved by the present invention is to provide a granular abrasive particle having a tip base that improves the physical properties such as extending the life of the abrasive particle, quickly reaching a stable PCR value, and maintaining the stable PCR value for as long as possible, thereby effectively performing precision processing including conditioning and dressing.

[0006] A granular abrasive particle having a tip base for solving the problem of the present invention comprises a cutting tip and a tip base, and in the abrasive particle having a polyhedral shape and a granular shape, the cutting tip protrudes from the tip base, the cutting tip is formed by removing a portion of the polyhedron, and the cutting tip is located inside the polyhedron.

[0007] In the abrasive particles of the present invention, the tip angle formed by the cutting tip and the tip base is smaller than the vertex angle of the polyhedron. The average diameter of the cutting tip is smaller than half the diameter of the polyhedron. The inclination and concave shape of the side surface of the cutting tip can be determined according to the grinding direction by the cutting tip and the support direction of the cutting tip. The cutting surface of the cutting tip can include a tip pattern having a line shape, a grid shape, an island shape, or a combination thereof. The cross-section of the tip pattern can be angled, curved, or a combination thereof. The periphery of the cutting tip can include a protrusion protruding in the direction of the cutting surface of the cutting tip.

[0008] In the abrasive particles of the present invention, the tip base is embedded in the bond layer. The height of the cutting tip exposed by the bond layer is smaller than the height of the cutting tip connected to the tip base.

[0009] According to the present invention, the granular abrasive particles having a tip base improve their physical properties, such as extending the life of the abrasive particles, rapidly reaching a stable PCR value, and maintaining the stable PCR value for as long as possible by applying the granular abrasive particles having a tip base. The improved physical properties enable effective precision processing, including conditioning and dressing.

[0010] Figure 1 is a drawing showing a first abrasive particle according to the present invention.

[0011] Figure 2 is a drawing showing a modified example of the first abrasive particle of the present invention.

[0012] Figure 3 is a drawing showing a second abrasive particle according to the present invention.

[0013] Figure 4 is a cross-sectional view showing a third abrasive particle according to the present invention.

[0014] Figure 5 is a cross-sectional view showing the fourth abrasive particle according to the present invention.

[0015] Figure 6 is a drawing expressing the cutting surface of the fourth abrasive particle of Figure 5.

[0016] Figures 7 and 8 are photographs showing the first and third abrasive particles according to an example of the present invention.

[0017] Figure 9 is a conceptual drawing comparing the polishing method using the polishing particles of the present invention (a), the conventional polishing particles (b), and the conventional CVD (c).

[0018] Fig. 10 is a graph showing PCR according to polishing time in the polishing particles (a, b, c) of Fig. 9.

[0019] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. The embodiments described below may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. In the drawings, exaggerated expressions are used for convenience of explanation. Meanwhile, terms indicating positions such as upper, lower, front, etc. are only related to those shown in the drawings. In practice, the abrasive particles can be used in any optional direction, and the spatial direction during actual use changes depending on the direction and rotation of the abrasive particles.

[0020] The present invention proposes an abrasive particle that effectively performs precision machining, including conditioning and dressing, by applying abrasive particles in the form of granules having a tip base, thereby improving the physical properties such as extending the life of the abrasive particle, quickly reaching a stable PCR value, and maintaining the stable PCR value for as long as possible. To this end, the abrasive particle in the form of granules having a tip base will be described in detail, and the precision machining effect, including the PCR value, by the abrasive particle will be described in detail. The abrasive particle according to the embodiment of the present invention can be applied to improve the effect of precision machining, such as a CMP pad conditioner, dressing, etc. Here, a CMP pad conditioner will be taken as an example.

[0021] Fig. 1 is a drawing showing a first abrasive particle (100) according to an embodiment of the present invention. However, it is not a drawing in the strict sense, and there may be components not shown in the drawing for the convenience of explanation.

[0022] According to Fig. 1, the first abrasive particle (100) includes a tip base (10) and a cutting tip (11). The cutting tip (11) is formed by removing a first area (Ra) of a polyhedron (13), and the upper surface forms a cutting surface (12). In order to represent the removed first area (Ra), the removed portion of the polyhedron (13) is expressed as a virtual line. The first abrasive particle (100) includes alumina (Al2O3), silica (SiO2), silicon carbide (SiC), alumina-zirconia (Al2O3-ZrO2), titanium diboride (TiB2), boron carbide (B4C), cubic boron nitride (CBN), diamond, etc. Preferably, superabrasive particles such as high-hardness diamond particles or CBN particles are widely used. These abrasive particles may be used alone or as a mixture of two or more types of particles.

[0023] The polyhedron (13) is a solid surrounded by a number of polygons. In the drawing, the polyhedron (13) is presented in a two-dimensional form for explanation, but the polyhedron can be expressed in various forms. Generally, diamond particles are used in CMP pad conditioners, and their size is about 100 to 200 μm. The shape of the diamond particles is mostly an octahedron or a cuboctahedral polyhedron, and recently, an octahedral shape has been used to improve PCR. The size of the polyhedron (13) may vary depending on the purpose of the first abrasive particle (100), the arrangement of a number of first abrasive particles (100), etc. The polyhedron (13) is said to be in the form of grains because it exists independently, in contrast to the CVD type in which the cutting tips are continuous.

[0024] As the polishing progresses, the position and shape of the cutting surface (12) change. The cutting surface (12) may be formed as a polygon, a circle, or a combination of a polygon and a circle when viewed perpendicular to the cutting surface. The shape of the cutting surface (12) may be determined by considering the purpose of the first abrasive particle (100), the arrangement of the first abrasive particle (100), etc. The side surface (Sa) of the cutting tip (11) may have various shapes, and the side surface (Sa) of the cutting tip will be described in detail later. The side surface (Sa) of the cutting tip (11) may be formed as an irregular surface that inevitably occurs during the process of removing the first area (Ra).

[0025] Since the cutting tip (11) is formed by removing the first region (Ra) of the polyhedron (13), the cutting surface (12) and the side surface (Sa) of the cutting tip (11) form a tip angle (θ1). If the tip angle (θ1) is 0 degrees, the cutting surface (12) and the side surface (Sa) form a right angle. The closer the tip angle (θ1) is to 0 degrees, the better, and it is better if it is smaller than 35 degrees of the octahedron, which has the smallest tip angle (θ1) among the polyhedrons (13). In other words, the tip angle (θ1) of the cutting tip (11) is preferably 0 degrees or more and 35 degrees or less, and more preferably 0 degrees or more and 30 degrees or less. In other words, the tip angle (θ1) is smaller than the vertex angle of the polyhedron (13). If the side surface (Sa) has a concave shape, a negative (-) tip angle (θ1) is possible.

[0026] The cutting tip (11) has a first width (Wa), which is an average width, and the tip base (10) has a second width (Wb), which is the maximum. The second width (Wb) is equal to or smaller than the diameter of the polyhedron (13). It is preferable that the first width (Wa) be smaller than half the diameter of the polyhedron (13), and the first width (Wa) can be 30㎛ or less, which is smaller than the conventional CVD method. The first width (Wa) can be adjusted to be as small as possible without breaking the cutting tip (11) during its use. The first width (Wa) can be appropriately determined in consideration of the use, arrangement, etc. of the first abrasive particles (100). The first width (Wa) being adjusted to be smaller than half the diameter of the polyhedron (13) and to be as small as possible without breaking is based on the technical idea of ​​maintaining the properties of the first abrasive particles (100) that distinguish the tip base (10). Accordingly, the first width (Wa) does not take into account the above technical idea, and it cannot be obtained through repeated experiments.

[0027] The tip base (10) is covered by a bond layer (BD), and the upper surface of the bond layer (BD) forms a bond line (BL). The bond line (BL) exists in the first region (Ra). Since the tip base (10) is buried by the bond layer (BD), the tip base (10) is more strongly fixed than the polyhedron (13) due to an anchor effect or the like. When the first abrasive particle (100) is strongly fixed, the risk of the first abrasive particle (100) falling off during the polishing process almost disappears. The tip base (10) may be completely buried by the bond layer (BD), but if the height of the tip base is sufficiently high compared to the size of the polyhedron, a part of the tip base (10) may be exposed to the outside of the bond layer (BD). Even if a part of the tip base (10) is exposed outside the bond layer (BD), it can be applied without any problem as long as there is little risk of the first abrasive particle (100) falling off during the polishing process.

[0028] The cutting tip (11) has a first height (Ha), and the tip base (10) has a second height (Hb). The bond layer (BD) has a third height (Hc), and the cutting tip (11) exposed by the bond layer (BD) has a fourth height (Hd). Since the tip base (10) is buried by the bond layer (BD), the first height (Ha) is greater than the fourth height (Hd). The fourth height (Hd) can be adjusted to the maximum extent possible so that the cutting tip (11) does not break during use and a desired polishing operation is performed. The fourth height (Hd) can be appropriately determined in consideration of the purpose, arrangement, etc. of the first abrasive particles (100).

[0029] FIG. 2 is a drawing showing a modified example of the first abrasive particle of the present invention. In this case, the modified example presents various shapes of the cutting tip (11), and for the first abrasive particle (100), reference will be made to FIG. 1.

[0030] According to Fig. 2, the first abrasive particle variations (100a, 100b, 100c, 100d) each include different first to fourth cutting tips (11a, 11b, 11c, 11d). The first cutting tip (11a) has both side surfaces (Sb, Sc) with the same inclination (θ1), and the second cutting tip (11b) has both side surfaces (Sb, Sc) with different inclinations (θ1, θ2). The third cutting tip (11c) has both side surfaces (Sb, Sc) that are concave, and the fourth cutting tip (11d) has one side surface (Sb) that is concave. Among the first to fourth cutting tips (11a, 11b, 11c, 11d), one side (Sb) of the two side surfaces (Sb, Sc) is a polishing direction in which polishing is performed, and the other side surface (Sc) is a support direction that supports the pressure applied to the first to fourth cutting tips (11a, 11b, 11c, 11d) during the polishing process. That is, the inclination and concave shape are determined according to the polishing direction and the support direction.

[0031] Figure 3 is a drawing showing a second abrasive particle (200) according to an embodiment of the present invention. At this time, the second abrasive particle (200) is arranged in a different direction than the first abrasive particle (100).

[0032] According to FIG. 3, the second abrasive particle (200) includes a tip base (20) and a cutting tip (21). The cutting tip (21) is formed by removing a second region (Rb) of a polyhedron (23), and the upper surface forms a cutting surface (22). In order to represent the removed second region (Rb), the removed portion of the polyhedron (23) is expressed as a virtual line. The second abrasive particle (200) is the same as the first abrasive particle (100) except for the shapes of the tip base (20) and the cutting tip (21). Specifically, the first and second widths (Wa, Wb) and the first to fourth heights (Ha, Hb, Hc, Hd) are as described for the first abrasive particle (100). In particular, since the tip base (20) is covered by a bond layer (BD), the first height (Ha) is greater than the fourth height (Hd). The cutting surface (22) of the second abrasive particle (200) may appear as a slope depending on the direction in which it is placed.

[0033] Fig. 4 is a cross-sectional view showing a third abrasive particle (300) according to an embodiment of the present invention. Here, the third abrasive particle (300) has been described with reference to the first abrasive particle (100), but can also be applied to the second abrasive particle (200).

[0034] According to FIG. 4, the third abrasive particle (300) includes a tip base (30) and a cutting tip (31). The cutting tip (31) is formed by removing a third region (Rc) of a polyhedron (33), and the upper surface forms a cutting surface (32). In order to represent the removed third region (Rc), the polyhedron (33) of the removed portion is expressed as a virtual line. The third abrasive particle (300) is the same as the first abrasive particle (100) except for the shapes of the tip base (30) and the cutting tip (31). Specifically, the first and second widths (Wa, Wb) and the first to fourth heights (Ha, Hb, Hc, Hd) are as described for the first abrasive particle (100). In particular, since the tip base (30) is covered by a bond layer (BD), the first height (Ha) is greater than the fourth height (Hd).

[0035] The cutting tip (31) includes a protrusion (34) protruding toward the cutting surface (32). The protrusion (34) has a fifth height (He) and includes a trench (35) in a grooved shape. The protrusion (34) is covered by a bond layer (BD). Since the protrusion (34) and the trench (35) are covered by the bond layer (BD), they are more strongly fixed than the first and second abrasive particles (100, 200) due to an anchor effect or the like. The protrusion (34) may form one or more circular bands, or may have a spiral shape starting from the cutting tip (31). The protrusions (34) may be connected continuously or may exist discontinuously. At this time, a part of the protrusions (34) may be exposed to the outside of the bond layer (BD).

[0036] FIG. 5 is a cross-sectional view showing a fourth abrasive particle (400) according to an embodiment of the present invention, and FIG. 6 is a drawing expressing a case where the cutting surface (12) of the fourth abrasive particle (400) of FIG. 5 is a square when viewed vertically. Here, the first abrasive particle (100) is described as an example, but the present invention can also be applied to the second and third abrasive particles (200, 300).

[0037] Referring to FIGS. 5 and 6, the fourth abrasive particle (400) has a tip pattern (40) provided on the cutting surface (12). The tip pattern (40) can divide the cutting surface (12) to sharpen the portion involved in actual polishing. The tip pattern (40) can be arranged in a line shape (a, 40a), a grid shape (b, 40c), an island shape (c, 40c), etc. Here, the case where the cross-section (41) of the tip pattern (40) is wedge-shaped is given as an example, but it can be formed into any one shape selected from a polygon or a curved surface. In other words, the cross-section (41) of the tip pattern (40) has an angle, a curve, or a combination thereof. The arrangement of the tip patterns (40) can be regularly arranged with a constant interval, but can also be irregularly arranged without a constant interval.

[0038] Figures 7 and 8 are photographs showing the first and third abrasive particles (100, 300) according to an embodiment of the present invention. In this case, the second abrasive particle (200) is not shown, but the present invention also applies to the second abrasive particle (200). The first and third abrasive particles (100, 300) are formed by removing the first and third regions (Ra, Rc) with a laser. The laser source was a pico-sec UV laser (15ps), the power was 7 W to 16 W, and the frequency was 100 to 300 kHz.

[0039] Referring to FIGS. 7 and 8, the first abrasive particle (100) includes a tip base (10) and a cutting tip (11), as described in FIG. 1. The tip base (10) and the cutting tip (11) are formed by removing the first region (Ra). As shown in FIG. 7, the first abrasive particles (a, b) having the shapes of the tip base (10) and the cutting tip (11) vary depending on the power, frequency, processing speed, etc. of the laser source. The third abrasive particle (300) includes a tip base (30), a cutting tip (31), and a protrusion (34), as described in FIG. 4. The tip base (30), the cutting tip (31), and the protrusion (34) are formed by removing the third region (Rc). As shown in Fig. 8, the third abrasive particles (a, b) having the shapes of the tip base (30), cutting tip (31) and protrusion (34) vary depending on the power, frequency, processing speed, etc. of the laser source.

[0040] The first to third abrasive particles (100, 200, 300) are subjected to processes such as attaching a polyhedron to a shank, laser processing the polyhedron to produce the first to third abrasive particles (100, 200, 300), and forming a bond layer (BD) in order to be applied to a CMP pad conditioner, etc. At this time, the bond layer (BD) can be implemented by plating, fusion, organic coating, etc. Here, in order to describe the first to third abrasive particles (100, 200, 300) in detail, the bond layer (BD) is not shown.

[0041] Fig. 9 is a conceptual comparison diagram of a polishing method employing an abrasive particle (a) according to an embodiment of the present invention, a conventional abrasive particle (b), and a conventional CVD (c), and Fig. 10 is a graph showing the PCR (Pad Cutting Rate) according to the polishing time in the abrasive particles (a, b, c) of Fig. 9. Here, the abrasive particle (a) according to an embodiment of the present invention is exemplified by the first abrasive particle (100), but is also applicable to the second and third abrasive particles (200, 300).

[0042] According to Fig. 9, the abrasive particle (a) of the present invention is formed by removing the first to third regions (Ra, Rb, Rc) from among the polyhedrons (13, 23, 33) as described above. The conventional abrasive particle (b) is the same as the polyhedrons (13, 23, 33) presented in the first to third abrasive particles (100, 200, 300). The conventional CVD (c) is applied to the protrusion (P20), and a CVD layer (P21) involved in actual polishing exists. Depending on the polishing progress direction (GD), the positions of the cutting surface (12, 22, 32) of the abrasive particle (a), the cutting surface (P10) of the abrasive particle (b), and the cutting surface (P22) of the abrasive particle (c) change. For convenience of explanation, it was assumed that the initial positions of the cutting surface (12, 22, 32) of the abrasive particle (a), the cutting surface (P10) of the abrasive particle (b), and the cutting surface (P22) of the abrasive particle (c) were the same.

[0043] Before the abrasive particle (b) reaches the contact area increase boundary point (P11), the contact area increases rapidly, making it difficult to proceed with polishing. When the abrasive particle (c) wears away and the underlying substrate (P20) is exposed, the cutting limit point (P23) is reached, making it difficult to proceed with further polishing. However, the abrasive particle (a) can continue polishing even when it reaches the positions of the comparative contact area increase boundary point (P11) and the cutting limit point (P23). Here, the positions of the contact area increase boundary point (P11) and the cutting limit point (P23) may vary depending on the shapes of the abrasive particles (b, c). Specifically, in the drawing, an example is given in which the contact area increase boundary point (P11) is reached later than the cutting limit point (P23), but the bonding area increase boundary point (P11) may be reached before the cutting limit point (P23).

[0044] According to Fig. 10, the PCR (Pad Cutting Rate), which is the polishing pad wear rate according to the polishing time (t), has different aspects for each of the abrasive particles (a, b, c). In the initial polishing, the abrasive particles (a) and (b) have almost the same behavior, and the abrasive particle (c) may have a somewhat lower initial PCR due to the flat cutting surface (P22). The polishing holding time (t) of the abrasive particle (a) a ) is the polishing retention time (t) of the polishing particles (b). b ) and the polishing retention time (t) of the polishing particles (c) c ) is relatively very long compared to the abrasive particle (a). The cutting tip (11, 21, 31) of the abrasive particle (a) has a smaller change in particle diameter than the abrasive particle (b), and the fourth height (hd) participating in the polishing is larger than that of the abrasive particle (c). Accordingly, the polishing holding time (t) of the abrasive particle (a) a ) can be maintained for a longer period of time compared to abrasive particles (b, c). In addition, the abrasive particles (b) have a shorter polishing time (t) due to the limitation of the thickness of the CVD layer (P21). b ) is relatively short.

[0045] The first to third abrasive particles (100, 200, 300) according to the embodiment of the present invention have a feature that they are not limited to the diamond particle size of 100 to 200 ㎛, which is generally used in CMP pad conditioners, because the contact area can be controlled by artificial processing such as laser.

[0046] Above, the present invention has been described in detail with reference to preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications are possible by a person having ordinary skill in the art within the scope of the technical idea of ​​the present invention.

[0047] *Explanation of symbols

[0048] 100, 200, 300, 400; 1st to 4th abrasive particles

[0049] 10, 20, 30; tip-lower half

[0050] 11, 11a, 11b, 11c, 11d, 21, 31; cutting tips

[0051] 12, 22, 32; cutting surface

[0052] 13, 23, 33; polyhedron

[0053] 34; protrusion 35; trench

[0054] 40, 40a, 40b, 40c; tip pattern

[0055] 41; Pattern cross section

Claims

1. In the abrasive particle which includes a cutting tip and a tip base and is polyhedral and granular in shape, The above cutting tip protrudes from the tip base, A grain-shaped abrasive particle having a tip base, characterized in that the cutting tip is formed by removing a portion of the polyhedron, and the cutting tip is located on the inside of the polyhedron.

2. A grain-shaped abrasive particle having a tip base, characterized in that the tip angle formed by the cutting tip and the tip base in the first paragraph is smaller than the vertex angle of the polyhedron.

3. A grain-shaped abrasive particle having a tip base, characterized in that in the first paragraph, the average diameter of the cutting tip is smaller than half the diameter of the polyhedron.

4. A grain-shaped abrasive particle having a tip base, characterized in that in the first paragraph, the inclination and concave shape of the side surface of the cutting tip are determined according to the grinding direction by the cutting tip and the support direction of the cutting tip.

5. In the first paragraph, a grain-shaped abrasive particle having a tip base characterized in that the cutting surface of the cutting tip includes a tip pattern having a line shape, a grid shape, an island shape, or a combination thereof.

6. In the fifth paragraph, a grain-shaped abrasive particle having a tip base characterized by a cross-section of the tip pattern having an angle, a curve, or a combination thereof.

7. A grain-shaped abrasive particle having a tip base, characterized in that in the first paragraph, the cutting tip includes a protrusion protruding in the cutting surface direction of the cutting tip around the cutting tip.

8. In the first paragraph, a grain-shaped abrasive particle having a tip base, characterized in that the tip base is buried in the bond layer.

9. In the 8th paragraph, a grain-shaped abrasive particle having a tip base, characterized in that the height of the cutting tip exposed by the bond layer is smaller than the height of the cutting tip connected to the tip base.

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