Single-side polishing apparatus, single-side polishing method, and polishing pad

Abstract

The present invention relates to a single surface polishing apparatus having a bottom stage with grooves for vacuum chucking, a detachable polishing stage fixed by vacuum chucking, a polishing pad, and a polishing head that holds a wafer, and polishes the surface of the wafer held by the polishing head in sliding contact with the polishing pad, wherein the polishing pad is formed by sequentially stacking a polishing layer that polishes the surface of the wafer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing stage, and the compression rate of the polishing pad is 16% or more. Thus, a single surface polishing apparatus is provided that can suppress deterioration of the NT quality of a wafer after polishing in single surface polishing of the wafer, particularly in single surface polishing using a detachable polishing stage of the vacuum chucking type.

Description

Technical Field

[0001] This invention relates to a single-sided polishing apparatus and method, as well as a polishing pad, and particularly to a single-sided polishing apparatus and method, and a polishing pad, for suppressing the deterioration of the nanotopography (NT) of the polished wafer. Background Technology

[0002] For single-sided polishing (CMP) used in the polishing of semiconductor wafers (e.g., Patent Document 1), considering the decrease in device operating rate caused by the preparation polishing of polishing pad replacement, a method is implemented to prepare the polishing pad in a separate device from the processing device (polishing device) and replace it together with the platform into the device. As a method for assembling and disassembling the platform, a detachable polishing platform (hereinafter also referred to as the assembly platform) is fixed to the bottom platform of the device (e.g., made of ceramic) by vacuum adsorption. The vacuum adsorption method involves forming concentric or radial grooves on the side of the bottom platform and placing the assembly platform in these grooves for vacuum adsorption. A known problem with this vacuum adsorption method is that when the thickness of the assembly platform is less than 20 mm, deformation occurs due to vacuum adsorption. Currently, assembly platforms with a thickness of 20 mm to 30 mm are used.

[0003] At this point, for the assembly / disassembly platform, when using a polishing pad (non-woven type) with a hardness (ASKER-C) of 60, a compression rate of 18%, and a thickness of 1.3mm, and when the NT quality level of the processed raw material is approximately NT(SQMM)_2mm = 6nm and NT(SQMM)_10mm = 13nm, the influence of the vacuum adsorption platform does not occur. In recent years, efforts have been made to suppress creep deformation of the polishing pad surface to improve flatness quality, and to harden the polishing pad. This has been implemented with a thickness of 0.8 mm or less, a hardness (ASKER-C) of 63, and a compression ratio of 12%. Furthermore, progress has been made in improving the NT quality of other processes, resulting in better NT quality in the raw materials supplied for single-sided polishing, with NT(SQMM)_2mm below 3.5 nm and NT(SQMM)_10mm below 12.0 nm. Under these conditions, the deterioration of NT in the polished wafer becomes significant. Existing technical documents Patent documents

[0004] Patent Document 1: Japanese Patent Application Publication No. 11-277408 Summary of the Invention The technical problem to be solved by the present invention

[0005] Due to the hardening of the polishing pad and the improvement in the NT quality of the raw material (wafer) before polishing, the unevenness of the polished surface is transferred to the wafer surface, causing NT degradation. Specifically, the mounting / unmounting platform deforms in a manner mimicking the grooves of the bottom platform. This deformation slightly affects the surface of the polishing pad, and this deformation is transferred to the wafer surface. In wafers where the surface NT quality has already been improved, this effect is amplified. For example, compared to before polishing, the NT after polishing may degrade by approximately 1-2 nm due to polishing a wafer with the aforementioned NT quality. Thus, in recent years, with the progress of NT improvement, sometimes high-quality raw materials with a wavelength of less than 3.5nm at 2mm and less than 12.0nm at 10mm are added, making it easy to observe the embossing on the wafer surface.

[0006] The present invention was made in view of the above-mentioned problems, and its object is to provide a single-sided polishing apparatus, a single-sided polishing method, and a polishing pad that can suppress the deterioration of the NT quality of the wafer after polishing in single-sided polishing of wafers (especially single-sided polishing using a vacuum adsorption type detachable polishing platform). Technical means to solve technical problems

[0007] To achieve the above objectives, the present invention provides a single-sided polishing apparatus comprising: a bottom platform having grooves on its top surface for vacuum adsorption; a detachable polishing platform fixed to the top surface of the bottom platform by vacuum adsorption; a polishing pad attached to the polishing platform; and a polishing head for holding a wafer, wherein the surface of the wafer held in the polishing head slides into contact with the polishing pad for polishing. The single-sided polishing apparatus is characterized in that... The polishing pad is formed by sequentially stacking a polishing layer for polishing the surface of the wafer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing platform. The compression rate of the polishing pad is 16% or higher.

[0008] Thus, especially if a PET sheet and an elastic layer are incorporated, and the overall compression ratio of the polishing pad is 16% or higher, even if the polishing platform or polishing pad undergoes slight deformation due to vacuum adsorption, mimicking the grooves used for vacuum adsorption on the bottom platform, the elastic layer of the polishing pad can absorb this deformation, the PET sheet layer can maintain a flat reference surface (the polishing surface of the polishing pad that contacts the wafer), and the unevenness of the polishing pad can be eliminated. By eliminating the unevenness of the polishing surface of the polishing pad, the NT degradation of the wafer after polishing caused by the grooves used for vacuum adsorption, which was previously observed, can be suppressed.

[0009] At this point, the elastic layer has a PET substrate, and on the PET substrate is an organosilicon sheet formed by thermal cross-linking of organosilicon resin. The PET substrate is located on the second adhesive layer side, and the silicone sheet is located on the third adhesive layer side. The thickness of the silicone sheet can be set to be between 30 μm and 500 μm.

[0010] If the elastic layer is made of the above-mentioned material, it can more effectively absorb the deformation caused by the grooves used for vacuum adsorption. Furthermore, if the thickness of the silicone wafer is 30 μm or more, the thickness unevenness of the silicone wafer can be reduced. Additionally, if the thickness of the silicone wafer is 500 μm or less, the deterioration of the flatness of the silicone wafer (especially the outer periphery) can be suppressed. Thus, values ​​within the above ranges are preferred in terms of thickness unevenness or flatness, and can suppress adverse effects on wafer polishing.

[0011] In addition, the thickness of the PET sheet can be set to 100μm or more and 350μm or less.

[0012] Thus, if the thickness of the PET sheet is 100 μm or more, a flat reference surface can be maintained more effectively. Furthermore, if the thickness of the PET sheet is 350 μm or less, the layer can be easily formed from a single sheet of PET.

[0013] Furthermore, the present invention provides a single-sided polishing method, wherein a single-sided polishing apparatus is used, comprising a bottom platform, a polishing platform fixed to the bottom platform by vacuum adsorption, a polishing pad attached to the polishing platform, and a polishing head holding the wafer. Polishing is performed by causing the surface of the wafer held on the polishing head to slide into contact with the polishing pad. The single-sided polishing method is characterized in that... Polishing is performed using the single-sided polishing apparatus of the present invention described above.

[0014] In such a single-sided polishing method, the elastic layer of the polishing pad can absorb the deformation caused by the grooves used for vacuum adsorption, and the PET sheet layer can maintain a flat reference surface, allowing polishing to be performed while eliminating the unevenness of the polishing pad. As a result, the unevenness of the polishing surface of the polishing pad can be eliminated, and the NT degradation of the wafer after polishing can be suppressed.

[0015] Furthermore, the present invention provides a polishing pad, which is attached to the polishing platform of a single-sided polishing device and used for polishing the surface of a wafer, characterized in that... The polishing pad is formed by sequentially stacking a polishing layer for polishing the surface of the wafer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing platform. The compression rate of the polishing pad is 16% or higher.

[0016] Such a polishing pad is particularly effective when polishing wafers by attaching it to a detachable polishing platform. It is a polishing pad that can suppress the deterioration of the NT of the polished wafer caused by the grooves for vacuum adsorption. The detachable polishing platform is fixed to the top surface of the bottom platform with grooves for vacuum adsorption by vacuum adsorption. Invention Effects

[0017] As described above, if the single-sided polishing apparatus, single-sided polishing method, and polishing pad of the present invention are used, the deterioration of the NT quality of the wafer after polishing can be suppressed in the single-sided polishing of the wafer. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating an example of the single-sided polishing apparatus of the present invention. Figure 2 A top view showing an example of a groove for vacuum adsorption on a bottom platform. Figure 3 This is a schematic diagram illustrating an example of the polishing pad of the present invention. Figure 4 This illustration shows an example of the polishing pad of the present invention maintaining a flat polished surface by absorbing deformation caused by the grooves used for vacuum adsorption. Figure 5 A graph showing the relationship between the compressibility of the polishing pad and the amount of NT degradation in the experiment. Figure 6 A graph showing the relationship between the degradation of NT (SQMM_2nm) (difference before and after processing) and its relative frequency in the examples and comparative examples. Figure 7 A graph showing the relationship between the degradation of NT (SQMM_10nm) (difference before and after processing) and its relative frequency in the examples and comparative examples. Figure 8 This is a schematic diagram illustrating an example of an existing polishing pad. Figure 9 This illustration shows an example of a polishing pad in an existing product deforming due to the grooves used for vacuum adsorption, resulting in unevenness on the polished surface. Detailed Implementation

[0019] As described above, when single-sided polishing is performed using a detachable polishing platform with vacuum adsorption, deformation occurs on the polishing platform or polishing pad due to the grooves used for vacuum adsorption on the bottom platform. With the improvement in NT quality of wafer surfaces in recent years, this deformation has a greater impact on NT quality. Therefore, the inventors of this application conducted in-depth research and discovered that if the polishing pad attached to the polishing platform is formed by sequentially stacking a polishing layer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing platform, and the compression ratio of the polishing pad is 16% or more, then the deformation caused by the aforementioned grooves for vacuum adsorption can be absorbed by the elastic layer, while the PET sheet layer maintains a flat polishing surface, eliminating unevenness in the polishing pad and preventing deterioration of the NT quality of the polished wafer, thus completing this invention.

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings, but the present invention is not limited thereto. Figure 1 An overview of an example of the single-sided polishing apparatus of the present invention is shown. Furthermore, the wafer polishing process typically consists of, for example, a primary polishing process (double-sided polishing apparatus), a secondary polishing process (single-sided polishing apparatus: non-woven fabric type polishing pad), and a fine polishing process (single-sided polishing apparatus: chamois type polishing pad). The single-sided polishing apparatus of the present invention is suitable for use in secondary polishing processes. However, it is not limited to this polishing method. And, as... Figure 1 As shown, the single-sided polishing apparatus 1 includes: a bottom platform 3 having a groove 2 for vacuum adsorption on the top surface; a detachable polishing platform 4 (for example, with a thickness of 30 mm or less) fixed to the top surface of the bottom platform 3 by vacuum adsorption; a polishing pad 5 of the present invention attached to the polishing platform 4; a polishing head 6 for holding the wafer W; and a nozzle 7 for supplying slurry to the polishing pad 5. The bottom platform 3 can vacuum-adhere the polishing platform 4 to its top surface via the groove 2. Furthermore, the bottom platform 3 is rotatable, allowing it to rotate as an integral part of the vacuum-adhere polishing platform 4. During polishing, the polishing head 6 holds the wafer W and ensures that the surface of the wafer W slides into contact with the polishing pad 5 for polishing. The bottom platform 3, polishing platform 4, polishing head 6, and nozzle 7 are not particularly limited in themselves; for example, the same bottom platform, polishing platform, polishing head, and nozzle as previously used can be used.

[0021] in addition, Figure 2 A top view showing an example of the groove 2 for vacuum adsorption on the bottom platform 3. Figure 2In the example shown, multiple concentric grooves and multiple radially extending grooves are combined to form a combination. However, this is not a limitation; multiple concentric grooves, multiple radially extending grooves, or grooves of other shapes may also be used. The number and depth of grooves are not particularly limited; the polishing platform 4 can be vacuum-adsorbed as appropriate.

[0022] Figure 3 An example of the polishing pad 5 of the present invention is shown. Additionally, to facilitate understanding of the layer positional relationships, the platforms (bottom platform 3 and polishing platform 4) are also shown in the figure. The polishing pad 5 extends from its surface side (the polishing surface, the side that is in contact with the wafer W to be polished) toward the polishing platform 4, and is composed of a polishing layer 8, a first adhesive layer 9, a PET (polyethylene terephthalate) sheet layer 10, a second adhesive layer 11, an elastic layer 12, and a third adhesive layer 13 in sequence. The polishing layer 8 is only required to polish wafer W and is not particularly limited; for example, it can be made of non-woven fabric. Examples of suitable materials include natural fibers such as cotton, linen, silk, and wool; and chemical fibers such as rayon, cupro fiber, lyocell, acetate, triacetate, polyester, nylon, acrylic, vinylon, polypropylene, polyurethane, and polyphenylene sulfide. A non-woven fabric made by impregnating nylon fibers with polyurethane is preferred, and its thickness can be reduced to approximately 0.8–1.5 mm through buffing.

[0023] The first adhesive layer 9, the second adhesive layer 11, and the third adhesive layer 13 only need to be able to bond and fix their respective upper and lower layers or platforms to each other, and there are no particular limitations. For example, the material can be made of natural rubber or acrylic. The thickness of the first adhesive layer 9, the second adhesive layer 11, and the third adhesive layer 13 can be set to about 30-50 μm, 30-50 μm, and 10-30 μm, respectively.

[0024] Furthermore, the PET sheet 10 can be, for example, a commercially available sheet of PET material, and its thickness is not particularly limited, and can be set to, for example, 100μm or more and 350μm or less. If it is 100μm or more, a flat polished surface can be maintained more effectively. Alternatively, multiple sheets can be stacked to form a thicker PET sheet 10, but since a thickness of about 350μm is sufficient to maintain the flatness of the polished surface, and one sheet is enough for this thickness, it is simple. Preferably, the thickness is about 188±10% (170μm to 207μm). Furthermore, there are no particular limitations on its thickness unevenness; for example, it can be set to a range of approximately 2% to 8%. The smaller the thickness unevenness, the more satisfactory it is in maintaining the flatness of the polished surface.

[0025] Furthermore, the elastic layer 12 can be any elastomer that can easily absorb the deformation caused by the grooves 2 used for vacuum adsorption, and is not particularly limited. Preferably, it has a PET substrate 14, and an organosilicon sheet 15 formed by thermal crosslinking of organosilicon resin is formed on the surface of the PET substrate 14. The PET substrate 14 is located on the side of the second adhesive layer 11, and the organosilicon sheet 15 is located on the side of the third adhesive layer 13. As an example, a coating liquid containing organosilicon resin (molecular weight of 5000 to 30000) composed of polyorganosiloxane can be coated on a 25 μm thick PET substrate 14, and crosslinked by calcination at 150°C to produce an organosilicon sheet 15 (thickness of 30 μm to 500 μm). With this material, the deformation caused by the grooves 2 can be absorbed more effectively. In addition, if the thickness of the organosilicon sheet 15 is 30 μm or more, it is easier to prepare an organosilicon sheet with less thickness unevenness. Furthermore, if the thickness of the silicone sheet 15 is less than 500 μm, its flatness (especially the outer periphery) can be suppressed, which is even more preferable. In the above examples, silicone sheets made by thermal cross-linking of silicone resin are used as an example, but silicone sponges and the like can also be used.

[0026] Furthermore, the polishing pad 5 of the present invention, which has a PET sheet layer 10 and an elastic layer 12, has an overall compression ratio of 16% or more in the thickness direction. There is no particular upper limit to the compression ratio; for example, 30% would be sufficient. However, considering the maintenance of the flatness of the polished surface during polishing, it is more preferable to set this level as an upper limit. If the compression ratio is less than 16%, the deformation caused by the groove 2 during polishing cannot be fully absorbed, resulting in unevenness on the surface of the polishing pad and deterioration of the NT quality of the polished wafer. On the other hand, if the polishing pad 5 of the present invention is used, it can effectively absorb the above-mentioned deformation and maintain the flatness of the surface while suppressing unevenness, thus preventing the deterioration of the NT quality of the polished wafer.

[0027] For example, for Figure 8 In the existing product shown, the polishing pad 105 is formed by stacking a polishing layer 108 (0.8 mm), a first adhesive layer 109 (40 μm), a PET sheet layer 110 (25 μm), and a second adhesive layer 111 (40 μm) on a polishing platform 104, which is vacuum-adsorbed onto a bottom platform 103 (vacuum adsorption groove 102). The compression ratio of this existing product is approximately 12%, such as... Figure 9 As shown, the deformation caused by the trench 102 cannot be completely absorbed by the polishing pad 105, resulting in unevenness on the surface of the polishing pad. This unevenness is transferred to the surface of the wafer being polished, adversely affecting the NT quality.

[0028] On the other hand, Figure 4In the example shown, the polishing pad 5 of the present invention is composed of a polishing layer 8 (0.8 mm), a first adhesive layer 9 (40 μm), a PET sheet layer 10 (188 μm), a second adhesive layer 11 (40 μm), an elastic layer 12 (a 25 μm PET substrate 14 and a 30 μm silicone sheet 15), and a third adhesive layer 13 (10 μm), with a compression ratio of 16%. In such a product of the present invention, the polishing pad 5 can fully absorb the deformation caused by the trench 2 to maintain a flat polished surface and can suppress the deterioration of the NT quality of the polished wafer.

[0029] Furthermore, the compression ratio referred to in this invention is based on JIS L-1096. As a method for determining the compression ratio, firstly, three test pieces (polishing pads) are overlapped, and an initial load W0 (50 gf / cm²) is applied. 2 The thickness T1 was read after 1 minute. Simultaneously, the load was increased to W1 (300 gf / cm²). 2 Then, the thickness T2 is read after 1 minute. Next, the compression ratio is calculated using the following formula. In addition, the thickness measuring machine used is the SE-15 manufactured by INTEC Inc.

[0030] [Mathematical Expression 1]

[0031] Here, we will describe the experiments conducted by the inventors of this application to discover a compression rate of 16%. To allocate the compression ratio of the polishing pad, polishing pads with varying thicknesses of the resin (silicone sheet) elastic layer and PET sheet were fabricated. Only the wafer was subjected to secondary polishing, and the amount of NT degradation after processing was measured using a WS2 (WaferSight2 manufactured by KLA). The relationship between the polishing pad compression ratio and NT quality (SQMM mode: 2mm / 10mm) was investigated.

[0032] Regarding the PET sheet thickness, sheets of 25, 50, 188, and 350 μm were prepared, with each thickness not exceeding 5%. Regarding the thickness of the silicone sheet for the elastic layer, the coating amount of the coating liquid containing silicone resin (molecular weight 30,000) was varied to achieve thicknesses of 10, 30, 100, and 500 μm, which were then calcined and crosslinked onto a 25 μm PET substrate. For a polishing pad composed of a polishing layer (non-woven fabric, 0.8 mm thick) + a first adhesive layer (40 μm) + a PET sheet + a second adhesive layer (40 μm) + an elastic layer (25 μm PET substrate + silicone sheet) + a third adhesive layer (10 μm), the compression ratio was investigated and distributed at 12%, 14%, 15%, 16%, 18%, and 20%. Additionally, at a compression ratio of 12%, [the following information is provided for reference]. Figure 8The same structure consists of a polishing layer + a first adhesive layer (40μm) + a PET sheet layer (25μm) + a second adhesive layer (40μm). A polishing pad with an assigned compression ratio was attached to a polishing platform, and the wafer was polished. The NT (tumor nitride) was then measured. For the polishing process, a slurry containing colloidal silica was used on a 300mm diameter wafer (P... - Single-sided polishing of the surface orientation <100> and the NT(SQMM)_2mm=3.5nm or less and NT(SQMM)_10mm=12.0nm or less after one polishing.

[0033] Table 1 summarizes the following factors: polishing pad compression ratio, PET sheet thickness, resin (silicone sheet) thickness of the elastic layer, NT degradation (average values ​​of 3 wafers), and the quality of NT degradation. Furthermore, regarding the quality of NT degradation, an average NT degradation of less than 1.0 nm at 2 mm and less than 1.4 nm at 10 mm in SQMM mode are considered acceptable (○), while values ​​of 1.0 nm or more and 1.4 nm or more are considered unacceptable (×). Furthermore, the relationship between the compressibility of the polishing pad and the amount of NT degradation is shown in the figure. Figure 5 ● indicates the 2mm case in SQMM mode, × indicates the 10mm case in SQMM mode.

[0034] [Table 1]

[0035] It has been confirmed that existing products with a compression ratio of 12-15% exhibit significant NT degradation before and after processing, while the products of the present invention with a compression ratio of 16% or higher tend to show less degradation. This is believed to be because the polishing pad of the present invention, having an elastic layer and a PET sheet layer and a compression ratio of up to 16% or higher, can absorb the slight deformation generated in the grooves of the vacuum adsorption polishing platform and maintain the polished surface. In addition, the quality of NT deterioration was investigated in the same way for cases with a compression rate of 16%, a PET sheet thickness of 100 μm, and a resin thickness of 30 μm for the elastic layer, and the results were satisfactory. Based on such experiments, the inventors of this application discovered a critical value for the compression ratio of the polishing pad at 16%.

[0036] Furthermore, in the single-sided polishing method of the present invention, as shown in the example... Figure 1 , 3The single-sided polishing apparatus 1 of the present invention, equipped with the polishing pad 5 of the present invention, is used to polish the surface of a wafer W. Specifically, a polishing platform 4 is placed on the top surface of a bottom platform 3, and the polishing platform 4 is vacuum-adsorbed and fixed by a groove 2. The polishing pad 5 is attached to the top surface of the polishing platform 4 beforehand. Meanwhile, the wafer W is held in a polishing head 6. While abrasive slurry is supplied from a nozzle 7, the polishing head 6 and the bottom platform 3 (and the polishing platform 4) are each rotated, causing the surface of the wafer W to slide into contact with the polishing pad 5 for polishing. As described above, since the polishing pad 5 can absorb the deformation caused by the trench 2 and maintain the flatness of the polished surface, it can suppress the deterioration of the NT of the polished wafer. Example

[0037] The following examples and comparative examples illustrate the present invention in more detail, but the present invention is not limited thereto.

[0038] (Example) Use such as Figure 1 , 3 The single-sided polishing apparatus of the present invention, equipped with the polishing pad of the present invention, is used for polishing wafers. The polishing pad is composed of a polishing layer (non-woven fabric with a thickness of 0.8 mm) + a first adhesive layer (40 μm) + a PET sheet layer (188 μm) + a second adhesive layer (40 μm) + an elastic layer (25 μm PET substrate + 30 μm silicone sheet) + a third adhesive layer (10 μm) and a compression ratio of 16%. The polishing pad is attached to a ceramic mounting platform (polishing platform), and after preparation, it is vacuum-mounted onto the bottom platform for polishing. Polishing is performed using a colloidal silica-based KOH polishing agent (slurry). The raw material being processed is 300mm in diameter, P... - The wafer has a surface orientation of <100>, has been polished once, and has NT(SQMM)_2mm = 3.5nm or less and NT(SQMM)_10mm = 12.0nm or less. The NT was measured before and after processing using WaferSight2. The amount of NT degradation after polishing was calculated, and the average value was obtained.

[0039] (Comparative Example) Use such as Figure 8 The diagram shows an existing single-sided polishing apparatus with a conventional polishing pad, used for polishing wafers. The polishing pad is composed of a polishing layer (non-woven fabric with a thickness of 0.8 mm) + a first adhesive layer (40 μm) + a PET sheet layer (25 μm) + a second adhesive layer (40 μm) and has a compression ratio of 12%. In addition, polishing, NT measurement before and after processing, and calculation of NT degradation (average value) after polishing were performed in the same manner as in the examples.

[0040] The relationship between the degradation of NT (SQMM_2nm) (difference before and after processing) and its relative frequency in the examples and comparative examples is shown in the figure. Figure 6 The average value of the degradation is shown in Table 2. Furthermore, the relationship at NT (SQMM_10nm) is shown in... Figure 7 The average value of the deterioration is shown in Table 3.

[0041] [Table 2] average 1.122 0.723 maximum 1.18 0.90 Minimum 1.04 0.55 s 0.049 0.127

[0042] [Table 3] average 1.463 1.284 maximum 1.84 1.57 Minimum 1.24 0.95 s 0.235 0.244

[0043] The comparison of NT degradation shows that the degradation is smaller when using the polishing pad (single-sided polishing device) of the present invention compared to processing with the polishing pad (single-sided polishing device) of existing products. Regarding the degradation (average) of NT (SQMM_2nm), the present invention achieves approximately 0.7nm for NTs less than 1.0nm, whereas existing products achieve over 1.0nm. Furthermore, regarding the degradation (average) of NT (SQMM_10nm), the present invention achieves approximately 1.3nm for NTs less than 1.4nm, unlike existing products which achieve over 1.4nm. Thus, it has been confirmed that even with raw materials (wafers) that have a good NT level before processing and are prone to deformation caused by trenches, NT quality degradation can be suppressed, and the wafers can be maintained at a level close to that before processing.

[0044] Furthermore, this invention is not limited to the above-described embodiments. The above embodiments are illustrative examples, and any technical solutions having a substantially identical structure and achieving the same effect as the technical concept described in the claims of this invention are included within the scope of protection of this invention.

Claims

1. A single-sided polishing apparatus comprising: a bottom platform having grooves on its top surface for vacuum adsorption; a detachable polishing platform fixed to the top surface of the bottom platform by vacuum adsorption; a polishing pad attached to the polishing platform; and a polishing head for holding a wafer, wherein the surface of the wafer held on the polishing head slides in contact with the polishing pad to perform polishing, characterized in that... The polishing pad is formed by sequentially stacking a polishing layer for polishing the surface of the wafer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing platform. The polishing pad has a compression ratio of 16% or higher according to JIS L-1096. The elastic layer has a PET substrate, and on the PET substrate is an organosilicon sheet formed by thermal cross-linking of organosilicon resin. The PET substrate is located on the second adhesive layer side, and the silicone sheet is located on the third adhesive layer side. The thickness of the silicone sheet is between 30 μm and 500 μm. The thickness of the PET sheet is between 100 μm and 350 μm.

2. A single-sided polishing method, wherein, A single-sided polishing apparatus is used, comprising a bottom platform, a polishing platform fixed to the bottom platform by vacuum adsorption, a polishing pad attached to the polishing platform, and a polishing head holding the wafer. Polishing is performed by causing the surface of the wafer held at the polishing head to slide into contact with the polishing pad. The single-sided polishing method is characterized by... Polishing is performed using the single-sided polishing apparatus according to claim 1.

3. A polishing pad, which is attached to the polishing platform of a single-sided polishing device and used for polishing the surface of a wafer, characterized in that, The polishing pad is formed by sequentially stacking a polishing layer for polishing the surface of the wafer, a first adhesive layer, a PET sheet layer, a second adhesive layer, an elastic layer, and a third adhesive layer for attaching to the polishing platform. The polishing pad has a compression ratio of 16% or higher according to JIS L-1096. The elastic layer has a PET substrate, and on the PET substrate is an organosilicon sheet formed by thermal cross-linking of organosilicon resin. The PET substrate is located on the second adhesive layer side, and the silicone sheet is located on the third adhesive layer side. The thickness of the silicone sheet is between 30 μm and 500 μm. The thickness of the PET sheet is between 100 μm and 350 μm.

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