CHEMICAL MECHANICAL POLISHING METHOD AND METHOD FOR FABRICATING SEMICONDUCTOR DEVICE

A chemical mechanical polishing method includes providing a pad conditioner, such that the pad conditioner includes a base and a plurality of tips protruding from a surface of the base, adjusting a surface roughness of an upper surface of each tip of the plurality of tips, and adjusting a polishing rate of chemical mechanical polishing using the adjusted surface roughness of the upper surfaces of the plurality of tips.

CROSS-REFERENCE TO RELATED APPLICATION

Korean Patent Application No. 10-2017-0126440 filed on Sep. 28, 2017, in the Korean Intellectual Property Office, and entitled: “Chemical Mechanical Polishing Method And Method For Fabricating Semiconductor Device,” is incorporated by reference herein in its entirety

BACKGROUND

The present disclosure relates to a chemical mechanical polishing method and a method for fabricating a semiconductor device, and more particularly, to a chemical mechanical polishing method using a pad conditioner and a method for fabricating a semiconductor device.

2. Description of the Related Art

In a planarization process using a chemical mechanical polishing (CMP) apparatus, the profile of a polishing pad has a great influence on the characteristics of the flatness of the wafer surface to be polished. Therefore, in order to smoothly perform a wafer planarization process by using the chemical mechanical polishing apparatus, the profile of the polishing pad must be maintained in a state suitable for the process.

SUMMARY

According to aspects of the present disclosure, there is provided a chemical mechanical polishing method that includes providing a pad conditioner, such that the pad conditioner includes a base and a plurality of tips protruding from a surface of the base, adjusting a surface roughness of an upper surface of each tip of the plurality of tips, and adjusting a polishing rate of chemical mechanical polishing using the adjusted surface.

According to aspects of the present disclosure, there is also provided a chemical mechanical polishing method that includes providing a pad conditioner including a base and a plurality of tips protruding from a surface of the base, determining an optimal surface roughness of an upper surface of each of the tips, adjusting a surface roughness of the upper surface of each of the tips such that the upper surface of each of the tips has the optimal surface roughness, performing conditioning on a polishing pad using the pad conditioner, and polishing a wafer using the polishing pad.

According to aspects of the present disclosure, there is also provided a method for fabricating a semiconductor device that includes providing a wafer, and polishing the wafer using a chemical mechanical polishing method, wherein the chemical mechanical polishing method includes providing a pad conditioner including a base and a plurality of tips protruding from a surface of the base, adjusting a surface roughness of an upper surface of each of the tips, and adjusting a polishing rate of chemical mechanical polishing using the adjusted surface roughness of the upper surface of the tip.

DETAILED DESCRIPTION

Hereinafter, a chemical mechanical polishing method according to some embodiments of the present disclosure will be described with reference toFIGS. 1 to 11.

FIG. 1is a flowchart explaining a chemical mechanical polishing method according to some embodiments of the present disclosure.FIG. 2is a schematic perspective view illustrating a pad conditioner according to some embodiments of the present disclosure.FIGS. 3a, 3b, 3cand 3dare enlarged views of a portion P ofFIG. 2.FIG. 4is a cross-sectional view taken along line X-X′ ofFIG. 2.FIG. 5is an enlarged view of a portion Q ofFIG. 4.FIG. 6is a schematic diagram illustrating the provision of a pad conditioner according to some embodiments of the present disclosure.

Referring toFIGS. 1 to 5, a pad conditioner100including a plurality of tips120is provided (S10). As illustrated inFIG. 2, the pad conditioner100may include a base110and a plurality of tips120protruding from the surface of the base110.

The base110may have a flat shape when viewed from above. For example, the base110may have a disc shape.

The base110may include a material having high strength and high hardness. For example, the base110may include at least one of ferroalloy, cemented carbide, and ceramic. For example, the base110may include cemented carbide based on tungsten carbide (WC), e.g., tungsten carbide-cobalt (WC—Co), tungsten carbide-titanium carbide-cobalt (WC—TiC—Co) and tungsten carbide-titanium carbide-tantalum carbide-cobalt (WC—TiC—TaC—Co). For example, the base110may include cemented carbide based on titanium carbide nitride (TiCN), boron carbide (B4C) and titanium boride (TiB2). For example, the base110may include a ceramic-based material containing at least one of, e.g., silicon nitride (Si3N4), silicon (Si), aluminum oxide (Al2O3), aluminum nitride (AlN), titanium oxide (TiO2), zirconium oxide (ZrOx), silicon oxide (SiO2), silicon carbide (SiC), silicon oxynitride (SiOxNy), tungsten nitride (WNx), tungsten oxide (WOx), diamond like coating (DLC), boron nitride (BN) and chromium oxide (Cr2O3).

The plurality of tips120may be formed on the base110. The plurality of tips120may be formed to protrude from the surface of the base110. For example, as illustrated inFIG. 4, the plurality of tips120may be formed to protrude upward from an upper surface of the base110.

The plurality of tips120may be spaced apart from each other on the base110. Further, the plurality of tips120may be repeatedly arranged on the base110. For example, the plurality of tips120may be arranged on the base110in the form of a mesh or a lattice, e.g., the plurality of tips120may be arranged on the base110equidistantly from each other along two different directions in a matrix pattern.

Each tip120protrudes from the surface of the base110and may include various shapes. The different shapes of the tips will be discussed in more detail below with reference toFIGS. 3a-3d.

For example, as shown inFIG. 3a, each tip120may have a truncated pyramid shape. Thus, each tip120may have a polygonal upper surface US. Although it is illustrated inFIG. 3athat the upper surface US of the tip120has a square shape in top view, the upper surface US of the tip120may have various polygonal shapes in top view, e.g., a rectangle, a pentagon, and the like. Further, the sidewall of the tip120may be inclined, e.g., a width of the sidewall of the tip120may be gradually reduced as a distance from the base110increases. For example, the cross-sectional area of a lower portion of the tip120in contact with the base110in a top view may be greater than the cross-sectional area of the upper surface US of the tip120in a top view.

In another example, as shown inFIG. 3b, each tip120may have a truncated cone shape. Thus, each tip120may have a circular upper surface US. Although it is illustrated inFIG. 3bthat the upper surface of the tip120has a circular shape, the upper surface of the tip120may have an elliptical shape. Further, the sidewall of the tip120may be inclined. For example, the cross-sectional area of the lower portion of the tip120in contact with the base110in a top view may be greater than the cross-sectional area of the upper surface US of the tip120in a top view.

In yet another example, as shown inFIG. 3c, each tip120may have a prism shape. Thus, each tip120may have a polygonal upper surface US, while the, e.g., entire, sidewall of the tip120may be substantially perpendicular to the upper surface of the base110. The cross-sectional area of the lower portion of the tip120in contact with the base110in a top view may be substantially equal to the cross-sectional area of the upper surface US of the tip120in a top view.

In still another example, as shown inFIG. 3d, each tip120may have a cylindrical shape. Thus, each tip120may have a circular upper surface US, while the, e.g., entire, sidewall of the tip120may be substantially perpendicular to the upper surface of the base110. The cross-sectional area of the lower portion of the tip120in contact with the base110in a top view may be substantially equal to the cross-sectional area of the upper surface US of the tip120in a top view.

Referring toFIGS. 3a-3d, a width W of the upper surface US of each tip120may range from about 10 μm to about 100 μm. Here, the width W of the upper surface US of the tip120means a diameter or a length of one side of the upper surface US. For example, inFIGS. 3aand 3c, the length of one side of the upper surface US of the tip120may range from about 10 μm to about 100 μm, e.g., a length of each side may be from about 10 μm to about 100 μm when the upper surface US has a rectangular or a pentagonal cross section in top view. For example, inFIGS. 3band 3d, the diameter of the upper surface US of the tip120may range from about 10 μm to about 100 μm e.g., a length of each of the diameters may be from about 10 μm to about 100 μm when the upper surface US has an elliptical cross section in top view.

A height H of each tip120may range from about 30 μm to about 250 μm. Here, the height H of the tip120means a distance from the upper surface of the base110to the upper surface US of the tip120along a direction normal to the upper surface of the base110. For example, inFIGS. 3ato 3d, the distance from the upper surface of the base110to the upper surface US of the tip120may range from about 30 μm to about 250 μm.

As shown inFIG. 5, each tip120may include a protrusion122and a cutting portion124. For example, each tip120illustrated inFIGS. 3a-3dreflects a schematic representation of a protrusion122with a cutting portion124thereon, e.g., the cutting portion124may be conformal on the protrusion to trace the profile of the protrusion122, so the height H represents a total height of the protrusion122with the cutting portion124, and the width W represents a total width of the upper surface US of the protrusion122with the cutting portion124.

The protrusion122of each tip120may be formed to protrude from the surface of the base110. That is, a plurality of protrusions122may be formed on the base110.

The plurality of protrusions122may be spaced apart from each other on the base110. Also, the plurality of protrusions122may be repeatedly arranged on the base110. For example, the plurality of protrusions122may be arranged on the base110in the form of a mesh or a lattice. Although it is illustrated inFIG. 5that the plurality of protrusions122have the same height, the plurality of protrusions122may have different heights.

The protrusion122of the tip120may be formed, for example, by machining the base110. For example, the plurality of protrusions122may be formed by etching a portion of the base110, e.g., by mechanical processing, laser processing, or etching. In this case, the protrusion122of the tip120may include the same material as the base110.

The cutting portion124of the tip120may be formed on the base110and the protrusion122. For example, the cutting portion124may be formed along the profile of the surface of the base110and the surface of the protrusion122, e.g., the cutting portion124may be formed conformally on the surface of the protrusion122and on the surface of the base110to trace the profile of the protrusion122on the base110. Accordingly, the cutting portion124may cover the upper surface of the base110, the sidewalls of the protrusions122, and the upper surfaces of the protrusions122.

The cutting portion124may include, e.g., chemical vapor deposition (CVD) diamond. For example, the cutting portion124may be formed by performing a diamond coating process on the base110and the protrusion122using a diamond coating apparatus. An example of a diamond coating apparatus is illustrated inFIG. 6.

Referring toFIG. 6, a diamond coating apparatus according to some embodiments may include a chamber10, a first electrode20a, a second electrode20b, a power source30, a gas supply pipe40, and a gas exhaust pipe50.

The chamber10may provide a space in which the diamond coating process is performed. The chamber10may be maintained in a vacuum or in a low pressure state, but is not limited thereto.

The gas supply pipe40connected to the chamber10may inject a gas into the chamber10. For example, the gas supply pipe40may inject a gas containing carbon (e.g., CH4) into the chamber10. The gas exhaust pipe50connected to the chamber10may exhaust a gas generated during the diamond coating process out of the chamber10.

The power source30may apply energy to the gas supplied by the gas supply pipe40. Thus, the gas supplied by the gas supply pipe40may generate, e.g., a plasma. For example, the power source30may be connected to the first electrode20aand the second electrode20bto form an electric field between the first electrode20aand the second electrode20b. The power source30may be an alternating current (AC) power source, but is not limited thereto, e.g., may be a direct current (DC) power source. By the power source30, atoms or ions containing carbon (e.g., carbon-containing radicals) may be formed in the chamber10.

The atoms or ions containing carbon may be deposited on the base110and the protrusions122of the conditioning pad100to form the cutting portion124, e.g., the atoms or ions containing carbon may be deposited on all exposed surfaces of the base110and protrusions122of the conditioning pad100. Thus, on the base110and the protrusions122, the cutting portion124including CVD diamond may be, e.g., continuously, formed.

The surface of the cutting portion124formed by the diamond coating process may have fine irregularities, e.g., unevenness. The degree of unevenness is called a surface roughness. Thus, as shown inFIG. 5, the upper surface US of each tip120may have a specific surface roughness defined by the irregularities in the top surface of the cutting portion124(enlarged portion R in dashed frame ofFIG. 5).

Referring again toFIG. 1, once the pad conditioner100is provided, as described previously with reference toFIGS. 2-6, the surface roughness of the upper surface US of each tip120in the pad conditioner100is adjusted (S20). In other words, the surface roughness of the cutting portion124in each tip120is adjusted. Adjusting the surface roughness of the upper surface US of each tip120may be performed in various ways.

In some embodiments, operation S20inFIG. 1of adjusting the surface roughness of the upper surface US of each tip120may be performed at the same time, e.g., simultaneously, as operation S10of providing the pad conditioner100. That is, for example, adjusting the surface roughness of the upper surface US of each tip120may be performed during formation of the cutting portion124in each tip120of the pad conditioner100.

For example, operation S20of adjusting the surface roughness of the upper surface US of each tip120may include adjusting the process conditions of the diamond coating process. As described above with reference toFIG. 6, operation SI0of providing the pad conditioner100may include forming the cutting portion124on the protrusions122using a diamond coating process. In this case, the surface roughness of the cutting portion124may be adjusted during its formation on the protrusions122by adjusting the process conditions of the diamond coating process.

For example, the surface roughness of the cutting portion124may be adjusted by adjusting the stoichiometry of the gas injected by the gas supply pipe40, the amount of energy applied by the power source30, the deposition temperature in the chamber10, the deposition pressure in the chamber10, and the deposition time. Thus, the surface roughness of the upper surface US of each tip120may be adjusted.

In some embodiments, operation S20inFIG. 1of adjusting the surface roughness of the upper surface US of each tip120may be performed after completion of operation S10of providing the pad conditioner100. That is, for example, adjusting the surface roughness of the upper surface US of each tip120may include reducing the surface roughness of the upper surface US of each tip120, after formation of the cutting portion124on the protrusions122of the pad conditioner100is complete. This will be described in more detail with reference toFIGS. 7 and 8.

FIGS. 7 and 8are schematic diagrams explaining the adjustment of the surface roughness of the upper surface of the tip120according to some embodiments of the present disclosure. For example, adjusting the surface roughness of the upper surface US of each tip120may include performing a dressing process on the upper surface of each tip120. For example, the dressing process may be performed on the upper surface of each tip120using a pad conditioner dressing apparatus200.

Referring toFIG. 7, the pad conditioner dressing apparatus200according to some embodiments may include a dressing turn table210, a dressing pad220, and a dressing slurry supply unit230.

The dressing turn table210may provide a space in which the dressing pad220is mounted. Further, while the dressing is performed, the dressing turn table210may rotate.

The dressing pad220may be disposed on the dressing turn table210. The dressing pad220may have, e.g., a disc shape, but is not limited thereto. The dressing pad220may include, e.g., a polymer having abrasion resistance. For example, the dressing pad220may include a pad which is impregnated with polyurethane in the nonwoven fabric. The nonwoven fabric may include polyester fibers. Alternatively, the dressing pad220may include, e.g., a pad on which a porous urethane layer is coated on a compressible polyurethane substrate.

The dressing slurry supply unit230may supply a dressing slurry240onto the dressing pad220. For example, the dressing slurry supply unit230may supply the dressing slurry240onto the dressing pad220using a nozzle.

The dressing slurry240may include a chemical solution containing an abrasive. The abrasive may include a material having high mechanical hardness and high strength. For example, the abrasive may include at least one of silica, alumina, and ceria. The chemical solution may include at least one of, e.g., de-ionized water, a surfactant, a dispersing agent, and an oxidizing agent. The dressing slurry240may be present in a suspension state by dispersing the abrasives in a chemical solution.

Referring toFIG. 8, a dressing process may be performed on the pad conditioner100. The pad conditioner100may be provided onto the upper surface of the dressing pad220. For example, the pad conditioner100may be provided onto the dressing pad220by a pad conditioner holder250, e.g., so the tips120of the pad conditioner100may face the dressing pad220. The pad conditioner holder250may hold the pad conditioner100, e.g., in a vacuum adsorption manner, but is not limited thereto. Although not shown, the pad conditioner holder250may be moved up and down using a pneumatic or hydraulic cylinder. The pad conditioner holder250moves up and down to apply pressure to the pad conditioner100such that the pad conditioner100can be brought into close contact with the dressing pad220, e.g., via the tips120.

During the dressing process, the dressing turn table210or the pad conditioner holder250may rotate. For example, the dressing turn table210and the pad conditioner holder250may rotate in opposite directions. However, the present disclosure is not limited thereto. For example, the pad conditioner holder250may rotate while the dressing turn table210is stopped, e.g., stationary. In another example, the pad conditioner holder250may be stopped while the dressing turn table210rotates.

The dressing slurry240may be supplied between the pad conditioner100and the dressing pad220. The dressing process may be performed on the surface of the pad conditioner100by a mechanical action through the mechanical contact between the pad conditioner100and the dressing pad220and a chemical action using the dressing slurry240, e.g., the mechanical and chemical actions of the dressing process may be performed between the tips120of the pad conditioner100and the dressing pad220. Thus, the surface roughness of the upper surface US of each tip120, i.e., of the cutting portion124in each tip120(which contacts the dressing pad220) may be reduced.

Referring again toFIG. 1, after the surface roughness of the upper surface US of each tip120in the pad conditioner100is adjusted (S20), the polishing rate of the chemical mechanical polishing is adjusted by using the surface roughness of the upper surface US of the adjusted tip120(S30). Hereinafter, operation S30of adjusting the polishing rate of the chemical mechanical polishing will be described in detail with reference toFIGS. 9 to 11.

FIG. 9is a flowchart explaining a chemical mechanical polishing method according to some embodiments of the present disclosure.FIG. 10is a schematic diagram explaining performing a conditioning process according to some embodiments of the present disclosure.FIG. 11is a schematic diagram explaining polishing a wafer according to some embodiments of the present disclosure.

Referring toFIG. 9, the surface roughness of the upper surface US of the tip120of the pad conditioner100is adjusted (S22). Since operation S22of adjusting the surface roughness of the upper surface US of the tip120of the pad conditioner100is substantially the same as operation S20inFIG. 1described previously, a detailed description thereof will be omitted below.

Next, referring toFIGS. 9 and 10, a conditioning process is performed on a polishing pad320using the pad conditioner100(S32). For example, the conditioning process is performed on the polishing pad320to adjust a surface of the polishing pad320in accordance with the surface roughness of the tips120of the pad conditioner100.

The polishing pad320may be disposed on a polishing turn table310. During the conditioning process, the polishing turn table310may rotate. The polishing pad320may have, e.g., a disc shape, but is not limited thereto. The polishing pad320may include, but is not limited to, e.g., a polyurethane pad.

The pad conditioner holder250may move up and down to apply pressure to the pad conditioner100such that the pad conditioner100can be brought into close contact with the polishing pad320, e.g., via the tips120. Further, during the conditioning process, the polishing turn table310or the pad conditioner holder250may rotate. For example, the polishing turn table310and the pad conditioner holder250may rotate in opposite directions. However, the present disclosure is not limited thereto. For example, the pad conditioner holder250may rotate while the polishing turn table310is stopped. In another example, the pad conditioner holder250may be stopped while the polishing turn table310rotates.

Thus, a conditioning process may be performed on the polishing pad320. In a continuous wafer polishing process, the polishing pad320may be damaged by a slurry or foreign matter. As a result, the profile of the polishing pad320may be altered to a state different from its initial state. In order to return the altered polishing pad320to its initial state, a conditioning process may be performed on the polishing pad320using the pad conditioner100.

The conditioning process may be performed ex-situ with the dressing process described above with reference toFIGS. 7 and 8, but is not limited thereto. In some embodiments, the conditioning process and the dressing process may be performed in-situ.

At this time, the surface roughness of the polishing pad320may be adjusted by using the adjusted surface roughness of the upper surface US of the tip120. That is, the surface roughness of the polishing pad320may be adjusted in operation (S32) in accordance with the adjusted surface roughness of the upper surface US of the tip120of the pad conditioner100performed in operation (S22). For example, by increasing the surface roughness of the upper surface US of the tip120in operation (S22), the surface roughness of the polishing pad320conditioned by the pad conditioner100(via the tips120) in operation (S32) may also be increased. In another example, by reducing the surface roughness of the upper surface US of the tip120in operation (S22), the surface roughness of the polishing pad320conditioned by the pad conditioner100(via the tips120) in operation (S32) may also be reduced.

Referring toFIGS. 9 and 11, once conditioning of the polishing pad320in accordance with the tips120of the pad conditioner100is complete, a wafer WF may be polished using the conditioned polishing pad320(S34).

The wafer WF may be provided onto the upper surface of the polishing pad320. For example, the wafer WF may be provided onto the polishing pad320by a polishing head410. The polishing head410may hold the wafer WF, e.g., in a vacuum adsorption manner, but is not limited thereto. The polishing head410may be moved up and down, e.g., using a pneumatic or hydraulic cylinder. The polishing head410may move in the vertical direction and apply pressure to the wafer WF such that the wafer WF can be brought into close contact with the polishing pad320.

During the polishing process of the wafer WF, the polishing turn table310or the polishing head410may rotate. For example, the polishing turn table310and the polishing head410may rotate in opposite directions. However, the present disclosure is not limited thereto. For example, the polishing head410may rotate while the polishing turn table310is stopped. In another example, the polishing head410may be stopped while the polishing turn table310rotates.

The polishing slurry supply unit510may supply a polishing slurry520between the wafer WF and the polishing pad320. For example, the polishing slurry supply unit510may supply the polishing slurry520between the wafer WF and the polishing pad320using a nozzle.

The polishing slurry520may include a chemical solution containing an abrasive. For example, the abrasive may include at least one of silica, alumina, ceria, zirconia, titania, barium titania, germania, mangania, and magnesia. The chemical solution may include, e.g., an oxidizing agent, a hydroxylating agent, an abrasive, a surfactant, a dispersing agent, and other catalysts.

By a mechanical action through the mechanical contact between the wafer WF and the polishing pad320and a chemical action through the polishing slurry520, chemical mechanical polishing may be performed on the wafer WF. At this time, the polishing rate of the chemical mechanical polishing may be adjusted by using the adjusted surface roughness of the polishing pad320, which is adjusted in accordance with the adjusted tips120of the conditioning pad100. That is, the polishing rate of the chemical mechanical polishing of the wafer WF may be adjusted by adjusting the surface roughness of the polishing pad320, which in turn, is adjusted by adjusting the upper surface US of the tips120of the pad conditioner100(S22).

As described above, by increasing or reducing the surface roughness of the upper surface US of the tips120of the conditioning pad100, the surface roughness of the polishing pad320may also be increased or reduced, respectively. The increased or reduced surface roughness of the polishing pad320may adjust the polishing rate of the chemical mechanical polishing of the wafer WF via the polishing pad320.

In other words, the chemical mechanical polishing method according to some embodiments adjusts the surface roughness of the upper surface US of the tip120of the pad conditioner100, which is used to adjust the surface roughness of the polishing pad320. Then, the polishing pad320with the adjusted surface roughness (in accordance with the adjusted tips120) is used to perform the polishing rate of the chemical mechanical polishing of the wafer WF according to the desired process, e.g., in accordance with desired process specification (e.g., type of abrasive used). Accordingly, the chemical mechanical polishing method according to some embodiments can realize an optimized and stabilized polishing rate for each process.

FIG. 12is a flowchart explaining a chemical mechanical polishing method according to some embodiments of the present disclosure.FIG. 13is a flowchart illustrating the determination of an optimal surface roughness according to some embodiments of the present disclosure.FIG. 14is a diagram explaining the provision of a test pad conditioner according to some embodiments of the present disclosure. For convenience of description, a repeated description similar to the description with reference toFIGS. 1 to 11will be only briefly explained or omitted.

Referring toFIG. 12, an optimal surface roughness is determined (S40). Operation S40of determining the optimal surface roughness may be performed before adjusting the surface roughness of the upper surface US of the tip120of the pad conditioner100(S22′).

In detail, referring toFIG. 13, operation S40of determining the optimal surface roughness may include providing a test pad conditioner including a test tip (S42), measuring the polishing rate of the chemical mechanical polishing while changing the surface roughness of the upper surface of the test tip (S44), and determining the optimal surface roughness using the measured polishing rate (S46).

The test pad conditioner may be an experimental pad conditioner used to determine the optimal surface roughness. That is, operation S42of providing a test pad conditioner including a test tip may be similar to operation S10of providing the pad conditioner100including the plurality of tips120inFIG. 1.

Operation S44of measuring the polishing rate of the chemical mechanical polishing while changing the surface roughness of the upper surface of the test tip may include providing a plurality of test pad conditioners and measuring the polishing rate of the chemical mechanical polishing using each of them. Measuring the polishing rate of the chemical mechanical polishing of a plurality of test pad conditioners is described in detail with respect toFIG. 14.

For example, a plurality of test pad conditioners, each including a test tip having an upper surface with a different surface roughness, may be provided. For example, referring toFIG. 14, a first test pad conditioner100T1, a second test pad conditioner100T2, and a third test pad conditioner100T3, each including a test tip having an upper surface with a different surface roughness, may be provided.FIG. 14illustrates that three test pad conditioners are provided, but the present disclosure is not limited thereto, e.g., three or more test pad conditioners may be provided.

Referring toFIG. 14, providing the first test pad conditioner100T1, the second test pad conditioner100T2, and the third test pad conditioner100T3may utilize operation S20inFIG. 1, i.e., adjusting the surface roughness of the upper surface US of each tip120inFIG. 1. For example, by adjusting the process conditions of the diamond coating process, a plurality of test pad conditioners, each including a test tip having an upper surface with a different surface roughness, may be provided, e.g., the process conditions of a diamond coating process in the first through third pad conditioners ofFIG. 14may be adjusted to adjust surface roughness of the test tips. In another example, by adjusting the degree of dressing of the test pad conditioner, a plurality of test pad conditioners, each including a test tip having an upper surface with a different surface roughness, may be provided e.g., the degree of dressing of the first through third pad conditioners ofFIG. 14may be adjusted to adjust surface roughness of the test tips.

The measurement of the polishing rate of the chemical mechanical polishing using a plurality of test pad conditioners may be similar to that described with reference toFIGS. 9 to 11. For example, the conditioning process may be performed on the polishing pad320using each of the first test pad conditioner100T1, the second test pad conditioner100T2, and the third test pad conditioner100T3. Then, the wafer WF may be polished by using the polishing pad320subjected to the conditioning process, e.g., different wafers WF may be polished by using polishing pads320subjected to the conditioning process via the first through this test pad conditioners100T1through100T3. Then, the polishing rate of the chemical mechanical polishing using each of the first test pad conditioner100T1, the second test pad conditioner100T2, and the third test pad conditioner100T3may be measured, e.g., in accordance with different degrees of surface roughness and slurry composition. Thus, the polishing rate of the chemical mechanical polishing may be measured while changing the surface roughness of the upper surface of the test tip.

Referring again toFIG. 13, the optimal surface roughness is determined using the measured polishing rate (S46). Here, the optimal surface roughness refers to the surface roughness of the upper surface US of the tip120of the pad conditioner100, which provides the polishing rate required according to the process. For example, the optimal surface roughness may be determined in accordance with measurement results, after testing the first test pad conditioner100T1, the second test pad conditioner100T2, and the third test pad conditioner100T3with different degrees of surface roughness and slurry composition, e.g., as will be described in more detail with reference toFIGS. 15-16.

FIG. 15is a graph explaining the determination of the optimal surface roughness using the measured polishing rate in some embodiments of the present disclosure. For reference,FIG. 15is a graph showing a change in the polishing rate according to the change in the surface roughness of the upper surface US of the tip120in the chemical mechanical polishing method using the polishing slurry520including a ceria abrasive. InFIG. 15, the surface roughness of the upper surface US of the tip120is obtained by measuring a protruding peak height (RPK) among lubricity evaluation parameters of a plateau structure surface.

Referring toFIG. 15, it can be seen that, in the chemical mechanical polishing method according to some embodiments, the polishing rate is improved as the surface roughness of the upper surface US of the tip120is reduced. That is, in the chemical mechanical polishing method using the polishing slurry520including the ceria abrasive, the reduced surface roughness of the polishing pad320can improve the polishing rate. It is understood that this is due to the characteristics of the ceria abrasive polishing the wafer WF. The ceria abrasive may form a Si—O—Ce bond with an oxide film of the wafer WF to remove the oxide of the wafer WF in a lump form. Accordingly, in the chemical mechanical polishing method using a ceria abrasive, the polishing rate tends to increase as the contact area between the polishing pad320and the wafer WF increases. That is, in some embodiments, by reducing the surface roughness of the upper surface US of the tip120, the surface roughness of the polishing pad320can be reduced, thereby improving the polishing rate.

In some embodiments, using the graph as inFIG. 15, the surface roughness providing the polishing rate required according to the process may be determined as the optimal surface roughness. For example, when a high polishing rate is required, the surface roughness of about 0.16 μm or less may be determined as the optimal surface roughness.

Further, in the chemical mechanical polishing method according to some embodiments, the surface roughness providing a stable polishing rate may be determined as the optimal surface roughness. As shown inFIG. 15, it can be seen that when the surface roughness of the upper surface US of the tip120is below a certain level, a change in the polishing rate is not large. For example, it can be seen that when the surface roughness of the upper surface US of the tip120ranges from about 0.04 μm to about 0.16 μm, a change in the polishing rate is not large, e.g., negligible. Accordingly, a surface roughness of about 0.04 μm to about 0.16 μm, e.g., about 0.04 μm to about 0.1 μm, may be determined as the optimal surface roughness.

FIG. 16is a graph explaining the determination of the optimal surface roughness using the measured polishing rate in some embodiments of the present disclosure. For reference,FIG. 16is a graph showing a change in the polishing rate according to a change in the surface roughness of the upper surface US of the tip120in the chemical mechanical polishing method using the polishing slurry520including a silica abrasive (as opposed to a ceria abrasive inFIG. 15). As inFIG. 15, inFIG. 16, the surface roughness of the upper surface US of the tip120is obtained by measuring a protruding peak height (RPK) among lubricity evaluation parameters of a plateau structure surface.

Referring toFIG. 16, it can be seen that, in the chemical mechanical polishing method according to some embodiments, the polishing rate is improved as the surface roughness of the upper surface US of the tip120is increased. That is, in the chemical mechanical polishing method using the polishing slurry520including the silica abrasive, the increased surface roughness of the polishing pad320can improve the polishing rate. It is understood that this is due to the characteristics of the silica abrasive polishing the wafer WF. The polishing slurry520containing the silica abrasive may dissolve the oxide of the wafer by a hydration reaction. Thus, in the chemical mechanical polishing method using the silica abrasive, the polishing rate tends to increase as the polishing pad320has a rough surface and the slurry can flow more easily. That is, in some embodiments, by increasing the surface roughness of the upper surface US of the tip120, the surface roughness of the polishing pad320can be increased, thereby improving the polishing rate.

In some embodiments, using the graph as inFIG. 16, the surface roughness providing the polishing rate required according to the process may be determined as the optimal surface roughness. For example, when a high polishing rate is required, the surface roughness of about 0.25 μm or more may be determined as the optimal surface roughness.

Further, in the chemical mechanical polishing method according to some embodiments, the surface roughness providing a stable polishing rate may be determined as the optimal surface roughness. As shown inFIG. 16, it can be seen that when the surface roughness of the upper surface US of the tip120is above a certain level, a change in the polishing rate is not large. For example, it can be seen that when the surface roughness of the upper surface US of the tip120is about 0.25 μm or more, a change in the polishing rate is not large, e.g., negligible. Accordingly, the surface roughness of about 0.25 μm or more, e.g., about 0.25 μm to about 0.5 μm, may be determined as the optimal surface roughness.

Referring again toFIG. 12, once the optimal surface roughness is determined (S40) in accordance with the test pad conditioner, e.g., via experimentation results as inFIGS. 15-16, the surface roughness of the upper surface US of the tip120of the pad conditioner100is adjusted (S22′) in accordance with the results determined in operation (S40). Adjusting the surface roughness of the upper surface US of the tip120of the pad conditioner100may include forming a plurality of tips120such that the upper surface US of the tip120has the determined optimal surface roughness, e.g., as determined in accordance with the multiple tips tested in operations S42through S46inFIG. 13.

Forming the plurality of tips120to have the determined optimal surface roughness may be performed in accordance with operation S20inFIG. 1, i.e., adjusting the surface roughness of the upper surface US of each tip120inFIG. 1. For example, the process conditions of the diamond coating process may be adjusted to form the plurality of tips120to have the determined optimal surface roughness. In another example, by adjusting the degree of dressing of the test pad conditioner, the plurality of tips120may be formed to have the determined optimal surface roughness.

For example, adjusting the surface roughness of the upper surface US of the tip120of the pad conditioner100may include forming the plurality of tips120such that the surface roughness of the upper surface US of the tip120rages from about 0.01 μm to about 0.16 μm. In another example, adjusting the surface roughness of the upper surface US of the tip120of the pad conditioner100may include forming the plurality of tips120such that the surface roughness of the upper surface US of the tip120rages from about 0.25 μm to about 0.5 μm, e.g., about 0.3 μm to about 0.5 μm.

Then, a conditioning process is performed on the polishing pad320using the pad conditioner100(S32′). According to some embodiments, the pad conditioner100including the plurality of tips120having an optimal surface roughness can form, e.g., adjust, the surface roughness of the polishing pad320required according to the process. In addition, according to some embodiments, the pad conditioner100including the plurality of tips120having an optimal surface roughness can form, e.g., adjust, the surface roughness of the polishing pad320to realize a stable polishing rate, e.g., regardless of the use time.

Then, the wafer WF is polished using the polishing pad320(S34′). The polishing pad320having the surface roughness required according to the process can provide the polishing rate of the chemical mechanical polishing required according to the process. Accordingly, the chemical mechanical polishing method according to some embodiments can realize an optimized polishing rate for each process, e.g., in accordance with slurry type. In addition, the chemical mechanical polishing method according to some embodiments can realize a stable polishing rate, e.g., in accordance with an optimal surface roughness as determined by the test tips.

FIG. 17is a flowchart explaining a method for fabricating a semiconductor device according to some embodiments of the present disclosure. For convenience of description, a repeated description similar to the description with reference toFIGS. 1 to 16will be only briefly explained or omitted.

Referring toFIG. 17, the wafer WF is provided (S100). As described above with reference toFIG. 11, the wafer WF may be provided onto the polishing pad320.

Then, the wafer is polished using the chemical mechanical polishing method according to some embodiments (S200). For example, the pad conditioner100including the plurality of tips120may be provided (S10ofFIG. 1). Then, the surface roughness of the upper surface US of each tip120may be adjusted (S20inFIG. 1). Then, the polishing rate of the chemical mechanical polishing may be adjusted (S30inFIG. 1). Operation S30of adjusting the polishing rate of the chemical mechanical polishing may include performing a conditioning process on the polishing pad320using the pad conditioner100(S32inFIG. 9) and polishing the wafer WF using the polishing pad320(S34inFIG. 9).

Thus, it is possible to provide a method for fabricating a semiconductor device, which realizes an optimized polishing rate for each process. In addition, it is possible to provide a method for fabricating a semiconductor device, which realizes a stable polishing rate.

By way of summation and review, in a continuous wafer planarization process, a polishing pad of a CMP apparatus may be damaged by slurry or foreign matter. As a result, the profile of the polishing pad may be altered to a state different from its initial state, which deteriorates the stability of the wafer planarization process. Accordingly, in order to continuously carry out the wafer planarization process by using the CMP apparatus, various kinds of pad conditioners capable of stably maintaining the profile of the polishing pad and a chemical mechanical polishing method using a pad conditioner are required.

Therefore, aspects of embodiments provide a method for fabricating a semiconductor device using a chemical mechanical polishing method capable of realizing an optimized polishing rate for each process. Aspects of embodiments also provide a chemical mechanical polishing method capable of realizing an optimized polishing rate for each process by adjusting the surface roughness of a pad conditioner.