Polishing pad

Abstract

The present application provides a polishing pad including an upper pad having a groove formed thereon and a lower pad positioned below the upper pad, wherein the polishing pad has a Cp value of 0.10 to 1.3 represented by Equation 1.

Description

Technical Field

[0001] This invention relates to a polishing pad. Background Technology

[0002] Chemical mechanical polishing (CMP) is a core process for flattening and mirror-finishing wafers or glass panels. Polishing is achieved through the mechanical and chemical action of a polishing pad and a slurry containing nanoparticles.

[0003] Figure 1 This is a schematic diagram of a CMP apparatus. The CMP apparatus polishes the object to be polished (e.g., a wafer) by pressing it against the surface of a waste polishing pad 6 fixed to a rotating stage 1 while the carrier 3 firmly holds the object to be polished. Specifically, while the carrier 3 and the rotating stage 1 rotate independently, a liquid slurry (abrasive) is applied to the polishing pad 6 from a nozzle 5, thereby performing chemical and mechanical polishing. Furthermore, as the dresser 4 is pressed against the polishing pad at a position separated from the object to be polished during the polishing process, the surface of the polishing pad is roughened, thus maintaining a rough surface condition.

[0004] Polishing pads are one of the main consumables used in chemical mechanical polishing processes. They are made of soft polymer materials to improve the mirror finish of surfaces and contain many grooves and pores on their surface to effectively remove polishing byproducts generated during the polishing process and to supply slurry.

[0005] Because polishing pads are constantly exposed to continuous mechanical friction between high-hardness nano-abrasive particles and the material being polished, the micropores on the surface become clogged, and the unevenness of the surface responsible for polishing is worn away, resulting in a decrease in polishing performance over time. Therefore, a pad surface finishing process involving periodic grinding of the surface is used to prevent the deterioration of polishing performance.

[0006] Because there is no practical recycling plan for polishing pads that have been used for a period of time, they are treated as industrial waste. However, due to the increasing consumption of polishing pads and the environmental pollution caused by their disposal, there is a need for in-depth research into recycling methods such as reprocessing.

[0007] As a conventional technique for recycling waste polishing pads, methods are known such as using compensating materials to compensate for the worn parts of the waste polishing pads, and recycling waste polishing pads by disassembling and reassembling the components that make up the waste polishing pads, such as the upper pad and the lower pad.

[0008] However, these methods fail to meet economic feasibility requirements in terms of the efficiency of waste polishing pad recycling. Furthermore, in this recycling process, the existing polished surface is ground and leveled, creating new grooves on the leveled surface. Since the pressure and friction applied during the grinding process can damage the pore shape of the leveled surface, there is a problem of not being able to ensure sufficient roughness of the polished surface of the recycled polishing pads.

[0009] [Existing technical documents]

[0010] [Patent Literature]

[0011] Korean Patent Publication No. 10-2020-0139907 Summary of the Invention

[0012] Technical issues

[0013] This invention is designed to solve the aforementioned problems of the prior art.

[0014] The purpose of this invention is to provide a polishing pad that has polishing performance comparable to a new polishing pad and excellent flatness even when the waste polishing pad is recycled and used.

[0015] Another object of the present invention is to provide a recycled polishing pad with excellent polishing performance manufactured by a recycling method.

[0016] Technical solution

[0017] To achieve the above objectives, the present invention provides a polishing pad, comprising:

[0018] An upper pad with a groove is formed thereon, and a lower pad is located below the upper pad.

[0019] The polishing pad has a Cp value of 0.10 to 1.3, as expressed by Equation 1 below.

[0020] [Equation 1]

[0021] Cp = Compression ratio × Thickness change rate / 100

[0022] Beneficial effects

[0023] According to the present invention, since the waste polishing pads are recycled through a simple process, the polishing pads provide excellent recycling efficiency and polishing performance comparable to new polishing pads.

[0024] Furthermore, according to the present invention, since the polishing pad has excellent polishing performance, the polishing pad can be used in the CMP process without its performance deteriorating due to recycling. Attached Figure Description

[0025] Figure 1This is a perspective view showing the structure of a representative CMP device.

[0026] Figure 2 This is a cross-sectional view illustrating a method for manufacturing a polishing pad according to an embodiment of the present invention.

[0027] Figure 3 This is a flowchart of a method for manufacturing a polishing pad according to one embodiment of the present invention.

[0028] Figure 4 This is a schematic diagram of a polishing pad according to one embodiment of the present invention.

[0029] Figure 5 This is a graph illustrating a method for calculating the compression ratio of a polishing pad according to an embodiment of the present invention. Detailed Implementation

[0030] In the following description, embodiments of the invention will be detailed with reference to the accompanying drawings, enabling those skilled in the art to readily implement the invention. However, the invention can be embodied in various different forms and is not limited to the embodiments described herein. Throughout this specification, similar components will be indicated by the same reference numerals.

[0031] When a component is described as being "connected to, coupled to, or mounted" in another component, it should be understood that it can be directly connected to or mounted in another component, but other components may exist between them. Conversely, when a component is described as being "directly connected to, set in, or mounted" in another component, it should be understood that no other components exist between them. Similarly, other expressions describing relationships between components, such as "...on top," "directly on top," "...between," "directly between," "...adjacent," "...directly adjacent," etc., should also be interpreted similarly.

[0032] Figure 2 This is a cross-sectional view illustrating a method for manufacturing a polishing pad according to one embodiment of the present invention. Figure 3 This is a flowchart of a method for recycling polishing pads according to one embodiment of the present invention. In the following, reference will be made to... Figure 2 and Figure 3 A method for manufacturing a polishing pad according to the present invention is described.

[0033] like Figure 2 As shown, the method for manufacturing a polishing pad according to the present invention includes the following steps:

[0034] a) Separate the adhesive layer 14 on the lower surface of the lower pad 13 from the waste polishing pad 100;

[0035] b) Grind the polishing surface on which the groove 15 of the waste polishing pad 100 is formed, and then make the polishing surface flat.

[0036] c) Form grooves 17 on the polishing surface of a flat waste polishing pad;

[0037] d) An adhesive layer 14 is formed on the lower surface of the waste polishing pad 13.

[0038] As a conventional technique for recycling waste polishing pads, methods are known such as using compensating materials to compensate for the worn parts of the polishing pad, and recycling the polishing pad by disassembling and reassembling the components that make up the polishing pad, such as the upper pad and the lower pad.

[0039] However, these methods are difficult to use in practice due to their low recycling efficiency and subsequent low economic viability.

[0040] This invention restores the hole shape damaged during the grinding process by grinding, thereby providing excellent roughness to the polished surface and thus providing polishing performance comparable to that of a new polishing pad.

[0041] In one embodiment of the invention, the leveling step b) can be performed by grinding downwards from the bottom of the groove by 0.3 mm to 1.3 mm, preferably 0.3 mm to 1.0 mm, and more preferably 0.3 mm to 0.8 mm.

[0042] In one embodiment of the present invention, the thickness of the flat polishing pad in step b) can be more than 2 mm, preferably 2.0 mm to 3.0 mm, and more preferably 2.5 mm to 2.9 mm.

[0043] In polishing pads manufactured in this manner, the thickness of the upper pad can be 0.6 mm to 1.7 mm, preferably 0.9 mm to 1.7 mm, more preferably 1.2 mm to 1.6 mm, and most preferably 1.4 mm to 1.6 mm.

[0044] In addition, the thickness of the lower pad in the polishing pad can be 0.7 mm to 1.4 mm, preferably 0.8 mm to 1.3 mm.

[0045] In one embodiment of the invention, the method for recycling waste polishing pads may not include a separate finishing process. In the prior art, a finishing process is performed to restore damaged roughness. However, the finishing process is not a process for restoring damaged holes, but rather a process for creating roughness by scraping the holes in the polished surface. Therefore, roughness may not be created on the polished surface at all, and the effect does not last long.

[0046] This invention solves the problem by grinding the damaged parts, thus providing sufficient roughness to the polished surface and maintaining the effect for a long time.

[0047] In one embodiment of the invention, a process for cleaning the waste polishing pad may be performed between step a) and step b). In this case, there is no particular limitation on the cleaning method, and it can be carried out by methods known in the art.

[0048] In one embodiment of the invention, the upper pad of the waste polishing pad may be made of a porous polyurethane material, but is not limited to that material.

[0049] In one embodiment of the invention, the groove 17 may have a depth of about 0.8 mm to about 1.0 mm, but the depth of the groove is not limited thereto. The groove may have a uniform depth or may have different depths. The process of forming the groove can be carried out by methods known in the art.

[0050] The present invention provides a recycled polishing pad recovered by the above method.

[0051] The reclaimed polishing pad of the present invention restores physical properties by grinding the polishing surface to a specific thickness, thereby providing excellent roughness to the polishing surface over a long period of time.

[0052] In the following text, reference will be made to Figure 4 A polishing pad manufactured in this invention is described by way of example.

[0053] The present invention provides a polishing pad comprising an upper pad having grooves formed thereon and a lower pad located below the upper pad, wherein the polishing pad has a Cp value of 0.10 to 1.3 as expressed by Equation 1 below.

[0054] [Equation 1]

[0055] Cp = Compression ratio × Thickness change rate / 100

[0056] The polishing pad includes an upper pad 11 on which grooves are formed. The upper pad 11 includes a polishing surface having a plurality of first grooves 17. The grooves 15 support a large flow of slurry on the surface of the polishing pad. The grooves 17 have a depth of about 0.8 mm to about 1.0 mm.

[0057] The upper pad 11 can be made of a porous polyurethane material and can have pores to support the fine flow, but is not limited thereto.

[0058] In some embodiments, the polishing pad may include a first adhesive layer 12, a lower pad 13, and a second adhesive layer 14.

[0059] The lower pad 13, located below the upper pad, can be made of a material that has restoring force to the pressed substrate and uniformly supports the upper pad 11 by cushioning the force. The lower pad 13 can be, for example, a polyurethane foam lower pad, an impregnated felt lower pad, a microporous polyurethane lower pad, a sintered polyurethane lower pad, or a polyolefin foam lower pad, but is not limited thereto. Typically, the lower pad 13 has a lower hardness than the upper pad 11. Furthermore, the lower pad 13 can have greater compressibility than the upper pad 11.

[0060] The first adhesive layer 12 may be located between the upper pad 11 and the lower pad 13 to attach the lower pad 13 to the upper pad 11. The second adhesive layer 14 may be disposed between the lower pad 13 and the table to fix the polishing pad 100 to the rotary table (table) of the polishing apparatus. Figure 1 The first adhesive layer 12 and the second adhesive layer 14 may include a pressure-sensitive adhesive (PSA) or a hot melt adhesive (HMA). For example, the pressure-sensitive adhesive may be an adhesive comprising a polyacrylic component, an epoxy component, or a rubber component, or a double-sided pressure-sensitive tape wherein the adhesive material is applied to both sides of a substrate (e.g., a PET film or felt), but is not limited thereto. For example, the hot melt adhesive may be a cured reactive hot melt adhesive, but is not limited thereto.

[0061] The polishing pad has a Cp value of 0.10 to 1.3, as expressed by Equation 1 below.

[0062] [Equation 1]

[0063] Cp = Compression ratio × Thickness change rate / 100

[0064] The inventors of this invention have discovered that when the upper layer of the upper pad is ground in order to reuse the waste polishing pad, the thickness of the upper and lower pads of the polishing pad each has a specific range, so that the compression rate and the thickness change rate of the entire polishing pad can have different values. After quantifying these values, the polishing performance and flatness of the recycled polishing pad can have good values ​​based on the result of multiplying these values.

[0065] As a result, the polishing pad of the present invention is characterized in that the recycled polishing pad has good polishing performance when the Cp value expressed by Equation 1 below is 0.10 to 1.3.

[0066] When the compression ratio is expressed as a percentage, the Cp value uses only the number excluding the percentage. Furthermore, the percentage value obtained by dividing the thickness change rate expressed as a percentage by 100 is used.

[0067] For example, in the case of a polishing pad with a compression rate of 1.4% and a thickness change rate of 26.5%, the Cp value is 0.37, which is 1.4 multiplied by 0.265.

[0068] In this invention, the Cp value can be 0.10 or higher, 0.13 or higher, 0.20 or higher, 0.35 or higher, 0.65 or higher, 0.85 or higher, 1.0 or higher, and 1.20 or higher, and can be 1.3 or lower, 1.0 or lower, 0.80 or lower, 0.60 or lower, 0.45 or lower, and 0.20 or lower.

[0069] When the Cp value is less than 0.10, the improvement in pad performance due to recycling as a recycled pad is not significant. When the Cp value is greater than 1.3, there is a problem of poor polishing performance.

[0070] In one embodiment of the present invention, the thickness of the polishing pad can be 2 mm or more, preferably 2.0 mm to 3.0 mm, and more preferably 2.5 mm to 2.9 mm.

[0071] In one embodiment of the invention, the thickness of the upper pad can be 0.6 mm to 1.7 mm, preferably 0.9 mm to 1.7 mm, more preferably 1.2 mm to 1.6 mm, and most preferably 1.4 mm to 1.6 mm.

[0072] In one embodiment of the present invention, the thickness of the underpad can be 0.7 mm to 1.4 mm, preferably 0.8 mm to 1.3 mm.

[0073] In one embodiment of the invention, the thickness change rate in Equation 1 above is the ratio of the current thickness to the thickness of the initially manufactured polishing pad, and can be determined by Equation 2 below.

[0074] [Equation 2]

[0075] Thickness change rate (%) = (Initial pad thickness - Pad thickness during analysis) × 100 / Initial pad thickness

[0076] In one embodiment of the invention, the polishing pad may have a polishing performance of 2,000 A / min to 2,650 A / min.

[0077] In one embodiment of the invention, the underpad may have a compression ratio of 1% to 8%.

[0078] In this invention, the compression ratio can be measured using the following equation 3, and the following equation 3 can be used to... Figure 5 Let's calculate it in detail.

[0079] [Equation 3]

[0080] Compression ratio (%) = (L3 - L4) × 100 / L3

[0081] (L3 is the initial thickness of the second cycle when the compressibility is measured in the viscoelastic apparatus, and L4 is the thickness during the second 30-second loading process.)

[0082] Specifically, refer to Figure 5 When a 1500g prepared sample (5×5cm) is repeatedly measured twice in a viscoelastic apparatus with a loading time of 30 seconds and an unloading time of 30 seconds, L3 and L4 are respectively set as the initial thickness of the second cycle and the thickness during the second 30-second loading process.

[0083] Compression ratios can be above 1%, above 2%, above 4%, and above 6%, and can be below 8%, below 6%, and below 4%. When the compression ratio is less than 1%, there is a problem of uneven polishing due to the low polishing uniformity across the entire surface of the wafer during the CMP polishing process. When the compression ratio exceeds 8%, even if the pads are recycled, the pad lifespan during actual use is too short, making it difficult to apply the pads to the polishing process.

[0084] Furthermore, when the compression ratio is too low, uneven polishing occurs. Therefore, the pad can be designed to ensure polishing uniformity by attaching a pad with compression properties to the underside of a high-hardness top pad.

[0085] In one embodiment of the invention, the polishing pad may be a recycled polishing pad used by recycling waste polishing pads.

[0086] The invention will now be described in detail with reference to embodiments. However, embodiments of the invention can be modified in various other forms, and the scope of the invention should not be construed as limited to the embodiments described in detail below. Embodiments of the invention are provided to explain the invention more fully to those skilled in the art.

[0087] Example 1: Recycling of Polishing Pads

[0088] [Examples 1-1 to 1-6 and Comparative Example 1-1]

[0089] Obtain the same type of polishing pads for disposal after use, and measure the thickness of the upper pad. The thickness of the upper pad is 1.9 mm, the thickness of the lower pad is 1.4 mm, and the initial thickness of the pads before use was 3.3 mm. The compression rate of the lower pad is 6%.

[0090] The recycling process is as follows.

[0091] First, the adhesive layer bonded to the lower pad is separated and removed from the waste polishing pad. Next, the waste polishing pad is washed and dried. Then, the polishing surface of the dried waste polishing pad is ground to different thicknesses using turning on a lathe for each embodiment and comparative example, and then the polishing surface is smoothed.

[0092] Next, the waste polishing pads are recycled by forming grooves on the polishing surface using a groove machining machine (CNC). Then, one side of double-sided tape is attached to the lower surface of the recycled polishing pad, followed by a 1.4mm thick backing pad, thus completing the pad recycling process. The same backing pad used initially is employed.

[0093] The results are shown in Table 1 below.

[0094] [Examples 2-1 to 2-5 and Comparative Example 2-1]

[0095] Except that the thickness of the upper pad is 1.9 mm, the thickness of the lower pad is 0.8 mm, the initial thickness of the pad before use is 2.7 mm, and the compression rate of the lower pad is 2.5%, the pads discarded after use are used for recycling process as in Example 1, and different thicknesses are ground for each example and comparative example.

[0096] Next, attach one side of the double-sided tape to the lower surface of the recycled polishing pad, and then attach a 0.8mm thick backing pad to complete the recycling process. Use the same backing pad as the initial one.

[0097] The results are shown in Table 2 below.

[0098] [Examples 3-1 to 3-3 and Comparative Example 3-1]

[0099] Except that the thickness of the upper pad is 1.9 mm, the thickness of the lower pad is 1.4 mm, the initial thickness of the pad before use is 3.5 mm, and the compression rate of the lower pad is 15.0%, the pads discarded after use are used for recycling process as in Example 1, and different thicknesses are ground for each example and comparative example.

[0100] Next, attach one side of the double-sided tape to the lower surface of the recycled polishing pad, and then attach a 1.4mm thick backing pad to complete the recycling process. Use the same backing pad as the initial one.

[0101] The results are shown in Table 3 below.

[0102] [Examples 4-1 to 4-4 and Comparative Example 4-1]

[0103] Except that the thickness of the upper pad is 1.55 mm, the thickness of the lower pad is 1.4 mm, the initial thickness of the pad before use is 3.0 mm, and the compression rate of the lower pad is 10.0%, the pads discarded after use are used for recycling process as in Example 1, and different thicknesses are ground for each example and comparative example.

[0104] Then, one side of the double-sided tape is attached to the lower surface of the recycled polishing pad, and then a lower pad with a thickness of 1.4 mm is attached to complete the recycled pad. As the lower pad, the same lower pad as the one initially used is used.

[0105] The results are shown in Table 4 below.

[0106] Experimental Example 1: Evaluation of Compression Ratio and Polishing Performance of Recycled Polishing Pad

[0107] The results of the compression ratio, thickness change rate, Cp value, and polishing performance of the manufactured recycled pads are summarized as follows.

[0108] Specifically, each recycled polishing pad is attached to Figure 1 the CMP apparatus shown, and the polishing performance of the wafer is evaluated. The results are shown in Tables 1 to 5 below.

[0109] <CMP Process Conditions>

[0110] Polishing table rotation speed (rpm): 120

[0111] Carrier rotation speed (rpm): 120

[0112] Wafer pressure (psi): 3.0

[0113] Slurry flow rate (fumed silica), 240 ml / min

[0114] Polishing time (seconds): 60

[0115] <Method for Measuring Compression Ratio>

[0116] In the present invention, the compression ratio refers to a value indicating the degree of possible volume change of an object when a force is applied to the object. The compression ratio in the present invention is calculated as follows.

[0117] 1) Preparation

[0118] Pad specimen size (width × length): 5 cm × 5 cm

[0119] Viscoelasticity measuring instrument (VMS, GNP Corporation)

[0120] Keep the temperature and humidity constant (25 °C, 50% RH)

[0121] 2) Measurement

[0122] - Condition: Measurement cycle: 2

[0123] Loading time: 30

[0124] Unloading time: 30

[0125] - Calculation: First, calculate the compression ratio using L3 and L4 as shown in the graph.

[0126] Here, L3 is the initial thickness of the second cycle when the compression rate is measured in the viscoelastic device, and L4 is the thickness during the second 30-second loading period.

[0127] Specifically, refer to Figure 5 When a 1500g prepared sample (5x5cm) is repeatedly measured twice in a viscoelastic apparatus with a loading time of 30 seconds and an unloading time of 30 seconds, L3 and L4 are respectively set as the initial thickness of the second cycle and the thickness during the second 30-second loading period.

[0128] This value refers to the compression amount in the second cycle. Then, calculate the compression ratio as shown in Equation 3 below.

[0129] [Equation 3]

[0130] Compression ratio (%) = (L3 - L4) × 100 / L3

[0131] [Table 1]

[0132]

[0133] *Cp = Compression ratio × Thickness change rate / 100

[0134] **Pad lifespan:** Availability time based on Cp predictions of pad availability.

[0135] [Table 2]

[0136]

[0137] [Table 3]

[0138]

[0139] [Table 4]

[0140]

[0141] The experimental results in Tables 1 to 4 above confirm that when each polishing pad sample is ground and recycled to a specific thickness that meets the Cp value within a specific range of 0.10 to 1.3, polishing performance above a certain level can be guaranteed.

[0142] However, in the cases of Comparative Examples 1-1 to 4-1, it was confirmed that the polishing performance was not guaranteed and that it was not easy to use as a recycling pad.

[0143] Furthermore, in the case of Example 1 listed in Table 1, the time spent from the start of use of Example 1-1 as an actual recycled pad to the use of the pads of Examples 1-6 as the final level of pads is defined as the pad life. Thus, the actual usable time of the recycled pad can be predicted. For specific calculation, when calculated based on a pad wear rate of 35 m / hr, it is possible to predict approximately 25.7 hours of use through a calculation of 0.9 * 1000 / 35.

[0144] Similarly, in the case of Example 2 shown in Table 2, using the calculation results of the pad life using the pads from Example 2-1 to Example 2-5, it is predicted that approximately 22.9 hours of use will be possible through the calculation of 0.8*1000 / 35.

[0145] Similarly, in the case of Example 3 shown in Table 3, using the calculation results of the pad life from the pad of Example 3-1 to the pad of Example 3-3, it is predicted that approximately 8.6 hours of use will be possible through the calculation of 0.3*1000 / 35.

[0146] Similarly, in the case of Example 4 shown in Table 4, using the calculation results of the pad life from the pad of Example 4-1 to the pad of Example 4-4, by calculating 0.5*1000 / 35, it is predicted that approximately 14.3 hours of use will be possible.

[0147] In the case of the recycled pad, a usage time of at least 20 hours should be ensured. As in Example 1 or Example 2, when the compression rate of the lower pad is within the range of 1% to 8%, a sufficient usage time of more than 20 hours is ensured. On the other hand, in the case of Example 3 or Example 4, where the compression rate of the lower pad exceeds 8%, a short usage time of the recycled pad was demonstrated, which significantly reduced the effectiveness of the recycled pad.

[0148] [Explanation of reference numerals in the attached figures]

[0149] 11: Upper pad; 12: First adhesive layer

[0150] 13: Underlay 14: Second adhesive layer

[0151] 15, 17: Groove 100: Waste polishing pad

[0152] 200: Recycle polishing pads

Claims

1. A polishing pad, comprising: An upper pad with a groove is formed thereon, and a lower pad is located below the upper pad. The polishing pad has a Cp value of 0.10 to 1.3, as expressed by Equation 1 below. The lower pad has a compression ratio of 2% to 8%. [Equation 1] Cp = compressibility Thickness change / 100 In Equation 1, the thickness change rate is the ratio of the current thickness to the initial thickness of the polishing pad. The polishing pad is a recycled polishing pad used by recycling waste polishing pads.

2. The polishing pad of claim 1, wherein, The thickness of the polishing pad is 2.0 mm to 3.0 mm.

3. The polishing pad of claim 2, wherein, The thickness of the upper pad is 0.6 mm to 1.7 mm.

4. The polishing pad according to claim 2, wherein, The thickness of the undermass is 0.7 mm to 1.4 mm.

5. The polishing pad of claim 1, wherein, The upper pad is made of porous polyurethane material.

6. The polishing pad of claim 1, wherein, The underlay is any one or more of polyurethane foam underlay, impregnated felt underlay, microporous polyurethane underlay, sintered polyurethane underlay, or polyolefin foam underlay.

7. The polishing pad of claim 1, wherein, The polishing pad has a polishing performance of 2,000 A / min to 2,650 A / min.

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