A polishing apparatus for improving edge grinding uniformity

Abstract

The application discloses a polishing device for improving edge grinding uniformity, comprising: a polishing head with a retaining ring; a porous disc located in the retaining ring; an adsorption film coated on the porous disc, and the adsorption or release of a wafer is realized through an air bag assembly; the outer ring of the porous disc has an extension part, at least part of the extension part is limitedly matched with the retaining ring, and the adsorption film is clamped by the inner wall of the retaining ring; the outer periphery of the extension part is formed with an accommodation gap to provide a deformation space for the adsorption film. The extension part is limitedly matched with the retaining ring, when the polishing head rotates to carry out a planarization process, the wafer is still uniformly pressed by the porous disc when a slight deviation is generated, and the edge polishing uniformity of the wafer is ensured; the outer periphery of the extension part is formed with the accommodation gap, and the micro-area deformation or wrinkle of the adsorption film in the edge area can be in the accommodation gap, the edge pressing force is more uniform in the polishing process, and the polishing uniformity of the wafer edge is improved.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor integrated circuit chip manufacturing technology, and in particular relates to a polishing device for improving edge grinding uniformity. Background Technology

[0002] In semiconductor integrated circuit chip manufacturing processes, planarization technology has become an indispensable key technology. Chemical Mechanical Planarization (CMP) is currently the only process technology that achieves global planarization. CMP equipment is fully automated, ensuring the safety of every module and every step in the wafer production process, which is of great significance for safe production, reducing losses, and improving production efficiency. CMP equipment mainly uses a polishing head to adsorb and transport the wafer onto a polishing pad for polishing. After polishing, the polishing head is transported back to the wafer loading holder for unloading and placement. During the polishing process, due to the combined effects of airbag pressure and clamping components on the adsorption film at the edges, the polishing uniformity at the edges is often worse than in the central area, resulting in performance differences in the processed devices in the wafer edge region. Generally speaking, the larger the controllable area of ​​the CMP edge region, the larger the effective area of ​​the wafer that can actually produce devices. Therefore, improving the polishing effect of the CMP edge region is an important task for improving wafer yield.

[0003] Patent CN2712547Y discloses a polishing head structure for chemical mechanical polishing, which improves polishing uniformity by redesigning the pressure bladder structure of the polishing head, separating a single bladder into multiple independent pressure chambers. However, its adjustment aims to better control the uniformity within and at the edges of the polishing pad, without specifically improving the polishing uniformity at the edges.

[0004] Patent TW481597B discloses an "Improvement of Chemical Mechanical Polishing Head Device", which solves the problem of excessive polishing at the edge of the wafer. However, when combined with Figures 5A and 5B, it does not solve the problem of wafer polishing uniformity.

[0005] Patent CN214054860U discloses a "Grinding Head for Chemical Mechanical Polishing," in which the lower edge of the adsorption film has a near-right angle curvature, thereby increasing the grinding rate at the wafer edge and making it closer to the grinding rate at the wafer center, thus improving the overall uniformity of the wafer surface, resulting in better wafer uniformity. However, even with a closer grinding rate between the wafer center and edge, the issue of uniformity in wafer edge polishing is not addressed. Furthermore, it cites Comparative Example 1, i.e., document... Figure 3 The document shows that when the edge curvature of the adsorption film is large, the resulting wafer edge polishing ratio is small, leading to a poor wafer edge polishing ratio. It should be noted that the document... Figure 2When the lower edge curvature, which is close to a right angle, is limited by the pressure expansion space of the adsorption membrane, it may produce micro-wrinkles, which will lead to poor uniformity of the edge area. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention provides a polishing apparatus for improving the uniformity of edge grinding, which improves the polishing uniformity of wafer edges, thereby increasing the effective area within the wafer that can be used to manufacture devices.

[0007] The technical solution adopted by this invention to solve its technical problem is: a polishing device for improving the uniformity of edge grinding, comprising:

[0008] Polishing head with retaining ring;

[0009] A perforated disk is located within the retaining ring;

[0010] An adsorption membrane is coated on the porous disk, and the wafer is adsorbed or released through the airbag assembly.

[0011] The outer ring of the porous disk has an extension portion, at least a portion of which is matched with a retaining ring for limiting and clamping the adsorption membrane with the inner wall of the retaining ring.

[0012] The outer periphery of the extension is formed with a receiving gap to provide deformation space for the adsorption membrane.

[0013] Furthermore, at least a portion of the accommodating gap faces the side where the wafer is located to prevent micro-deformation or wrinkling of the outer ring of the adsorption film.

[0014] Furthermore, the maximum radial width on one side of the extension is 0.5-2 mm.

[0015] Furthermore, the extension portions are arranged continuously in the circumferential direction; or, the extension portions are arranged at uniform intervals in the circumferential direction.

[0016] Furthermore, the radial width of the extension decreases from top to bottom, and the upper part of the outer ring of the extension is matched with the retaining ring for limiting, while the lower part of the outer ring forms the receiving gap with the inner wall of the retaining ring.

[0017] Furthermore, the sidewall thickness of the adsorption membrane is H, and the difference between the maximum and minimum single-sided radial width of the extension is 1H-10H.

[0018] Furthermore, the sidewall of the outer ring of the extension smoothly transitions to the bottom wall of the porous disk; the sidewall of the outer ring of the extension smoothly transitions to the top wall of the extension.

[0019] Furthermore, the extension includes at least two arc-shaped protrusions, and the side of the arc-shaped protrusions facing the retaining ring is an arc surface, with the receiving gap formed between adjacent arc-shaped protrusions.

[0020] Furthermore, the number of the arc-shaped protrusions is multiple, and they are evenly distributed on the outer periphery of the porous disk.

[0021] Furthermore, the sum of the outer diameter of the extension and the double-layer thickness of the adsorption film is equivalent to the inner diameter of the retaining ring; the sum of the outer diameter of the extension and the double-layer thickness of the adsorption film is equivalent to the inner diameter of the wafer.

[0022] Furthermore, the extension portion is separately disposed from the perforated disk; or, the extension portion is integrally disposed with the perforated disk.

[0023] This invention proposes to ensure consistent pressure applied to the wafer surface by increasing the size of the porous disk, and to reduce the formation of micro-wrinkles in the adsorption film by optimizing the edge spatial distribution, thereby ensuring the overall uniformity of the wafer surface while optimizing the uniformity of the edge region.

[0024] The technical solution proposed in this invention is to optimize the size of the porous disk covered by the adsorption film to ensure the area of ​​the adsorption film covering the wafer, and at the same time optimize the edge structure of the porous disk to ensure the deformation space of the adsorption film during the pressure expansion process, so that the adsorption film can be spread relatively smoothly on the back of the wafer to participate in the grinding, thereby improving the pressure uniformity of the wafer edge and thus improving the polishing uniformity of the wafer edge.

[0025] The beneficial effects of this invention are: 1) When the extension and retaining ring are matched, the wafer is still uniformly pressed by the porous disk when it is slightly offset during the planarization process of the polishing head rotation, ensuring uniform polishing of the wafer edge; 2) The outer periphery of the extension forms a receiving gap, and the micro-deformation or wrinkles generated by the adsorption film in the edge area can be contained in the receiving gap, making the edge pressure force more uniform during the polishing process and improving the polishing uniformity of the wafer edge; 3) The area of ​​the outer ring of the extension and the retaining ring is correspondingly reduced, reducing the micro-deformation or wrinkles generated in the edge area of ​​the adsorption film. Attached Figure Description

[0026] Figure 1 This is a cross-sectional view of the polishing head in the polishing state of the present invention.

[0027] Figure 2 This is a cross-sectional view of the state in which the polishing head adsorbs the wafer in this invention.

[0028] Figure 3 This is a three-dimensional structural diagram of the perforated disk in Embodiment 1 of the present invention.

[0029] Figure 4 This is a cross-sectional view of the perforated disk in Embodiment 1 of the present invention.

[0030] Figure 5 for Figure 4 Enlarged view of the structure at point C.

[0031] Figure 6 This is a schematic diagram of the fit between the retaining ring and the extension in Embodiment 1 of the present invention.

[0032] Figure 7 This is a three-dimensional structural diagram of the perforated disk in Embodiment 2 of the present invention.

[0033] Figure 8 This is a cross-sectional view of the perforated disk in Embodiment 2 of the present invention.

[0034] Figure 9 for Figure 8 Enlarged view of the structure at point D in the image.

[0035] Figure 10 This is a schematic diagram of the fit between the retaining ring and the extension in Embodiment 2 of the present invention.

[0036] Figure 11 This is a three-dimensional structural diagram of the perforated disk in Embodiment 3 of the present invention.

[0037] Figure 12 This is a cross-sectional view of the perforated disk in Embodiment 3 of the present invention.

[0038] Figure 13 for Figure 12 Enlarged view of the structure at point E in the image.

[0039] Figure 14 This is a schematic diagram of the fit between the retaining ring and the extension in Embodiment 3 of the present invention.

[0040] Figure 15 This is a three-dimensional structural diagram of the perforated disk in Embodiment 4 of the present invention.

[0041] Figure 16 This is a cross-sectional view of the perforated disk in Embodiment 4 of the present invention.

[0042] Figure 17 for Figure 16 Enlarged view of the structure at point F in the image.

[0043] Figure 18 This is a schematic diagram of the fit between the retaining ring and the extension in Embodiment 4 of the present invention.

[0044] Figure 19 This is a three-dimensional structural diagram of the perforated disk in Embodiment 5 of the present invention.

[0045] Figure 20 This is a top view of the perforated disk in Embodiment 5 of the present invention.

[0046] Figure 21 for Figure 20 Sectional views from AA and BB perspectives.

[0047] Figure 22 This is a schematic diagram of the fit between the retaining ring and the extension in Embodiment 5 of the present invention.

[0048] Figure 23 The figures show the removal rate curves at various points on the wafer before and after the improvement of the porous disk in this invention.

[0049] Among them, 1-polishing head, 11-holding ring, 2-porous disk, 21-extension, 211-arc-shaped protrusion, 22-top wall of porous disk, 23-bottom wall of porous disk, 3-adsorption film, 4-airbag assembly, 5-wafer, 6-accommodation gap. Detailed Implementation

[0050] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0051] A polishing apparatus for improving edge grinding uniformity includes a polishing head 1 with a retaining ring 11, a porous disk 2 located within the retaining ring 11, and an adsorption film 3 covering the porous disk 2. The adsorption film 3 can adsorb or release the wafer 5 through an airbag assembly 4. The function of the airbag assembly 4 is prior art and will not be described in detail.

[0052] The outer ring of the porous disk 2 has an extension 21, at least a portion of which engages with the retaining ring 11 for positioning and clamps the adsorption membrane 3 against the inner wall of the retaining ring 11. At the same time, an accommodating gap 6 is formed on the outer periphery of the extension 21, thereby providing deformation space for the adsorption membrane 3.

[0053] The extension 21 and the porous disk 2 can be separate components, detachably connected. Pressure is applied to the extension 21 towards the inside of the porous disk 2 via the adsorption membrane 3, allowing them to remain stably connected. Of course, the extension 21 and the porous disk 2 can also be integrated, and there is no specific limitation.

[0054] like Figure 1 The image shown is a cross-sectional view of polishing head 1 in the polishing state, as shown below. Figure 2The diagram shows a cross-sectional view of the polishing head 1 holding the wafer 5. The porous disk 2 serves to fix the adsorption film 3, which is typically made of rubber or silicone, is soft, and has good elasticity. In a static state, the adsorption film 3 adheres to the porous disk 2. In the working state, an external mechanism introduces air into the air chamber through the air passage. The adsorption film 3 expands under the air pressure, applying pressure to the surface of the wafer 5. The polishing pad and polishing fluid then planarize the wafer 5 through chemical and mechanical action.

[0055] When the adsorption membrane 3 deforms, gas is uniformly introduced through the pores of the porous disk 2 and fills the gas cavity. Since there are no other hardware structures in the middle region of the adsorption membrane 3, the pressure is relatively uniform, resulting in good polishing uniformity. However, in the edge regions, where the porous disk 2 adheres to the adsorption membrane 3, micro-deformation or wrinkles may occur, leading to poorer uniformity. Furthermore, a small gap exists between the wafer 5 and the holding ring 11 during polishing. If the wafer 5 has a flat-edge configuration, this gap will significantly increase. During the planarization process while the polishing head 1 rotates, the wafer 5 may shift in a certain direction under centrifugal force, causing uneven edge polishing.

[0056] To improve upon the above two situations, this invention provides an extension 21 on the outer ring of the porous disk 2. At least a portion of this extension 21 engages with the retaining ring 11, ensuring that even if the wafer 5 experiences slight displacement during polishing, it still receives uniform pressure from the porous disk, guaranteeing uniform polishing of the wafer 5's edges. This engagement refers to the fact that the sum of the outer diameter of the extension 21 and the double-layer thickness of the adsorption film 3 is approximately equal to the inner diameter of the retaining ring 11 and the inner diameter of the wafer 5. Therefore, there is no large gap, or even no gap, between the wafer 5 and the retaining ring 11. During the planarization process of the polishing head 1 rotating, the porous disk can achieve uniform pressure within this area.

[0057] Meanwhile, a receiving gap 6 is formed on the outer periphery of the extension 21. The micro-deformation or wrinkles generated by the adsorbed film 3 in the edge region can be contained within this receiving gap 6. In other words, the receiving gap 6 provides deformation space for the adsorbed film 3, making the edge pressure force more uniform during polishing, thereby improving the polishing uniformity of the wafer 5 edge. Moreover, when the receiving gap 6 is formed on the outer periphery of the extension 21, the area of ​​the limiting fit between the outer ring of the extension 21 and the retaining ring 11 is correspondingly reduced. In other words, the squeezing contact area between the extension 21 and the retaining ring 11 on the adsorbed film 3 is reduced, which also helps to reduce the micro-deformation or wrinkles generated in the edge region of the adsorbed film 3.

[0058] Example 1

[0059] like Figures 3-4As shown, the extension 21 is continuously arranged circumferentially, and the radial width of the extension 21 on one side decreases from top to bottom. The upper part of the outer ring of the extension 21 is limited and fitted with the retaining ring 11, and the lower part of the outer ring forms a receiving gap 6 with the inner wall of the retaining ring 11. Figure 6 As shown.

[0060] In other words, the upper part of the outer ring of the extension 21 is relatively wide, and the sum of its width and the double-layer thickness of the adsorption film 3 is equivalent to the inner diameter of the retaining ring 11 and the inner diameter of the wafer 5. That is, the position of the porous disk 2 is relatively limited by the retaining ring 11, ensuring that the porous disk 2 will not deviate under the action of centrifugal force. Its pressurized coverage area is slightly larger than the area of ​​the wafer 5, which can ensure that even if the wafer 5 experiences slight slippage, it can still complete the grinding within the coverage area of ​​the porous disk 2.

[0061] The lower part of the outer ring of the extension 21 is narrower, thus forming a receiving gap 6 between the upper and lower parts of the outer ring of the extension 21, which faces the side where the wafer 5 is located. When the inner wall of the retaining ring 11 and the upper part of the outer ring of the extension 21 clamp the adsorption film 3, the presence of the receiving gap 6 makes the adsorption film 3 more loose when it is attached to the porous disk 2, preventing the formation of micro-deformation or wrinkles on the outer ring of the adsorption film 3. During the polishing process, the edge pressure force is more uniform, thereby improving the polishing uniformity of the wafer 5 edge. During the polishing process, the gas introduced into the adsorption film cavity causes the adsorption film to expand and press the wafer onto the polishing disk. Under the action of polishing fluid and mechanical force, the surface material is removed. In this process, the more uniform the pressure applied by the adsorption film to the back of the wafer, the better the uniformity of the wafer polishing removal rate. In the edge area of ​​the adsorption film, due to the tension of the porous disk and the space of the receiving gap, if the receiving space is small, micro-deformation or wrinkles are easily generated at the edge. In areas of slight deformation or wrinkles, the downward pressure will differ from that in smooth areas, resulting in differences in the polishing removal rate at the wafer edge.

[0062] In this embodiment, the width gradient of the upper and lower parts of the outer ring of the extension 21 decreases, that is, the outer ring sidewall of the extension 21 is a slope, which is inclined from top to bottom and towards the center of the porous disk 2.

[0063] Define the sidewall thickness of the adsorption film 3 as H. Then, the difference between the maximum and minimum single-sided radial width of the extension 21 is 1H-10H. If the difference between the maximum and minimum single-sided radial width of the extension 21 is too large, the size of the porous disk 2 will be too small, failing to cover the processing surface of the wafer 5, resulting in a low edge removal rate, reducing the overall uniformity of the wafer, and causing a decrease in yield. If the width difference is too small, firstly, the deformation space of the adsorption film 3 is limited, making it prone to wrinkles, which reduces edge uniformity; secondly, when the deformation and compression of the adsorption film 3 causes excessive wear with the retaining ring 11 or the back of the wafer 5, the debris generated by the wear will fall onto the polishing pad and participate in the process grinding of the front side of the wafer, causing defects or scratches on the front side of the wafer, which may lead to wafer scrap in severe cases.

[0064] Specifically, the maximum radial width on one side of the extension 21 is 0.5-2mm, that is... Figure 5 The left side of the middle O line is the extension 21, and the radial width of the extension 21 on one side is S=0.5-2mm.

[0065] The outer ring of the extension 21 smoothly transitions to the bottom wall 23 of the porous disk 2, and the outer ring of the extension 21 smoothly transitions to the top wall 22 of the porous disk 2. Therefore, when the adsorption membrane 3 covers the porous disk 2 and its extension 21, the adsorption membrane 3 will not be stretched at the connection between the extension 21 and the rest of the porous disk 2, allowing the adsorption membrane 3 to be smoothly distributed along the circumference of the porous disk 2, preventing the formation of wrinkles.

[0066] Example 2

[0067] like Figures 7-10 As shown, in this embodiment, the upper part of the outer ring of the extension 21 is limited to the retaining ring 11, and the lower part of the outer ring forms a receiving gap 6 with the inner wall of the retaining ring 11. However, the width of the upper and lower parts of the outer ring of the extension 21 does not decrease in a gradient, and the lower part of the outer ring of the extension 21 forms an arc-shaped recess facing the center of the porous disk 2.

[0068] The other structures are the same as in Embodiment 1, and will not be described again.

[0069] Example 3

[0070] like Figures 11-14 As shown, in this embodiment, the upper part of the outer ring of the extension 21 is limited to the retaining ring 11, and the lower part of the outer ring forms a receiving gap 6 with the inner wall of the retaining ring 11. However, the width of the upper and lower parts of the outer ring of the extension 21 does not decrease in a gradient, and the lower part of the outer ring of the extension 21 forms a rectangular recess facing the center of the porous disk 2.

[0071] The other structures are the same as in Embodiment 1, and will not be described again.

[0072] Example 4

[0073] like Figures 15-18 As shown, in this embodiment, the cross-section of the extension 21 is a semi-circle with the opening facing the center of the porous disk 2. The middle part of its outer ring is matched with the retaining ring 11. The upper part and the lower part of its outer ring are both formed with the inner wall of the retaining ring 11. That is to say, part of the retaining gap 6 faces the side where the wafer 5 is located, and part of it is away from the side where the wafer 5 is located. The upper part and the lower part of the outer ring of the extension 21 are both formed to prevent the outer ring of the adsorption film 3 from forming micro-area deformation or wrinkles.

[0074] Example 5

[0075] like Figure 19 As shown, in this embodiment, the extension 21 is evenly spaced around the circumference and includes at least two arc-shaped protrusions 211. The side of the arc-shaped protrusions 211 facing the retaining ring 11 is an arc surface, and an accommodating gap 6 is formed between adjacent arc-shaped protrusions 211.

[0076] In this embodiment, there are multiple arc-shaped protrusions 211, and they are evenly distributed on the outer periphery of the porous disk 2. For example... Figures 20-22 As shown, AA cross-sectional view shows the position of the porous disk 2 with the extension 21, and BB cross-sectional view shows the position of the porous disk 2 without the extension 21. The extension 21 is to the left of line O.

[0077] To further illustrate the advantages of the present invention, Table 1 shows the removal rates of wafer 5 along the diameter direction using the structure of the porous disk 2 in Examples 1-5 (Improved Version 1 and Improved Version 2) and using the porous disk 2 without the extension 21 (Unimproved Version).

[0078] Table 1

[0079]

[0080] Table 1 shows that, under the same test conditions, the polishing rates of improved version 1, improved version 2, and the unimproved version of the multi-hole disk were tested. The test wafer was a 6-inch polishing wafer (wafer radius 75mm), and the surface of the polishing wafer was... For thin films, the absolute value of the wafer radius parameter is the distance from the wafer center, with positive and negative signs representing left and right directions. It can be seen that the unimproved multi-hole disk polishing rate data shows a relatively uniform removal rate along the wafer diameter, with an average removal rate of 1942 A / min and a variance of 125 A / min. It is worth noting that in the wafer edge region, taking 72mm and -72mm as examples, a significant difference in polishing rate occurs, with a difference of 960 A / min. This indicates that edge wrinkles lead to uneven edge removal rates.

[0081] In the improved porous disk polishing rate data 1, the removal rate along the wafer diameter is more uniform, with an average removal rate of 1855 A / min and a variance of 59 A / min, significantly lower than the unimproved data, indicating higher uniformity. Specifically, taking 72mm and -72mm as examples, the difference in polishing rate is only 163 A / min, significantly lower than the unimproved data, indicating a significant improvement in the uniformity of the edge polishing rate. These data demonstrate that the improved porous disk can significantly improve the uniformity of edge removal rate by reducing the probability of edge wrinkles.

[0082] Furthermore, the improved porous disc polishing rate data 2 shows that by adjusting the pressure parameters, the polishing rate at the edges can be increased, exceeding that at the center. During this process, the polishing rates at -72mm and 72mm are 2515A / min and 2508A / min, respectively, which are comparable, indicating that the edge removal rate remains very uniform. This data demonstrates that the improved porous disc has a significant effect on improving the polishing uniformity of the edge area.

[0083] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

Claims

1. A polishing apparatus for improving edge grinding uniformity, comprising: Polishing head (1), with retaining ring (11); The perforated disk (2) is located inside the retaining ring (11); An adsorption membrane (3) is tightly fitted and coated onto the porous disk (2), and adsorption or release of the wafer (5) is achieved through an airbag assembly (4); characterized in that, The outer ring of the porous disk (2) has an extension (21), at least a portion of which is matched with a retaining ring (11) for limiting and clamping the adsorption membrane (3) with the inner wall of the retaining ring (11). The outer periphery of the extension (21) is formed with a receiving gap (6) to provide deformation space for the deformation of the adsorption membrane (3) after being squeezed by external force.

2. The polishing apparatus according to claim 1, characterized in that: At least a portion of the accommodating gap (6) faces the side where the wafer (5) is located, in order to prevent micro-deformation or wrinkles from forming on the outer edge of the adsorption film (3).

3. The polishing apparatus according to claim 1, characterized in that: The maximum radial width of one side of the extension (21) is 0.5-2 mm.

4. The polishing apparatus according to claim 1, characterized in that: The extension (21) is continuously arranged circumferentially; or, the extension (21) is evenly spaced circumferentially.

5. The polishing apparatus according to claim 1, characterized in that: The radial width of the extension (21) decreases from top to bottom, and the upper part of the outer ring of the extension (21) is matched with the retaining ring (11) for limiting, and the lower part of the outer ring forms the receiving gap (6) between the inner wall of the retaining ring (11).

6. The polishing apparatus according to claim 5, characterized in that: The sidewall thickness of the adsorption membrane (3) is H, and the difference between the maximum and minimum single-sided radial width of the extension (21) is 1H-10H.

7. The polishing apparatus according to claim 5, characterized in that: The side wall of the outer ring of the extension (21) smoothly transitions to the bottom wall of the perforated disk (2); the side wall of the outer ring of the extension (21) smoothly transitions to the top wall of the extension (21).

8. The polishing apparatus according to claim 1, characterized in that: The extension (21) includes at least two arc-shaped protrusions (211), and the side of the arc-shaped protrusions (211) facing the retaining ring (11) is an arc surface, and the receiving gap (6) is formed between adjacent arc-shaped protrusions (211).

9. The polishing apparatus according to claim 8, characterized in that: The number of the arc-shaped protrusions (211) is multiple, and they are evenly arranged on the outer periphery of the porous disk (2).

10. The polishing apparatus according to claim 1, characterized in that: The sum of the outer diameter of the extension (21) and the double-layer thickness of the adsorption film (3) is equivalent to the inner diameter of the retaining ring (11); the sum of the outer diameter of the extension (21) and the double-layer thickness of the adsorption film (3) is equivalent to the inner diameter of the wafer (5).

11. The polishing apparatus according to claim 1, characterized in that: The extension (21) is separately disposed from the perforated disk (2); or, the extension (21) is integrally disposed with the perforated disk (2).

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