A carrier head, chemical mechanical polishing apparatus, and polishing method

Abstract

The application discloses a bearing head, a chemical mechanical polishing device and a polishing method, and belongs to the technical field of chemical mechanical polishing. The bearing head comprises a coupling disc, an upper base, a lower base, a leveling air bag and a square flexible film. The leveling air bag is arranged between the coupling disc and the upper base, has a ring structure, is circumferentially divided into multiple independent leveling chambers, and is used for adjusting the inclination angle of the bearing head to realize macro parallelism adjustment between the square substrate and the polishing pad. The square flexible film is arranged below the lower base, has a square contour, is internally provided with multiple annular chambers located in a central region and corner chambers located at four sharp corner positions, and each chamber is connected with an independent air path, and is used for realizing micro pressure distribution control on each region of the square substrate. The leveling air bag and the square flexible film work cooperatively, macro leveling is first performed through the leveling air bag, and then micro pressurization is performed through the square flexible film, so that the global planarization precision of the square substrate and polishing uniformity can be effectively improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor manufacturing technology, and more particularly to a chemical mechanical polishing (CMP) technology, specifically to a carrier head, CMP equipment, and polishing method. Background Technology

[0002] Chemical mechanical polishing (CMP) is an ultra-precision machining technique that achieves global planarization of a workpiece surface through the synergistic effect of chemical etching and mechanical grinding. In integrated circuit manufacturing, CMP is widely used for the planarization of silicon wafer surfaces and is one of the core technologies for achieving nanoscale global planarization.

[0003] In chemical mechanical polishing (CMP), a support head (also known as a polishing head) is used to hold the substrate and press it against a rotating polishing pad. The support head typically includes a coupling disk connected to the polishing shaft, a base, and a flexible membrane disposed beneath the base. Multiple independently pressurizable chambers are formed between the flexible membrane and the base. By applying gas at different pressures to each chamber, the polishing pressure on different areas of the substrate can be independently controlled. Furthermore, the flexible membrane usually has vacuum adsorption through-holes, allowing for the adsorption and transport of the substrate through vacuum extraction.

[0004] However, the aforementioned carrier heads are all developed for circular wafers (typically 300mm in diameter). In the field of advanced packaging, the demand for using square substrates (such as board-level packaging substrates with sizes like 310×310 and 510×515) as processing carriers is becoming increasingly urgent in order to improve area utilization and production efficiency. Compared to circular wafers, square substrates can provide a larger effective working area, creating a space advantage for multi-chip system-in-package (SoC) applications. However, with the increase in the size and weight of square substrates, warpage problems are becoming increasingly prominent, and the traditional circular carrier head technology is difficult to directly apply to the polishing of large square substrates.

[0005] The geometric characteristics of square substrates present technical challenges not present with circular substrates. First, the rectangular outline and sharp corners of square substrates result in a significant difference in linear velocity between the corner and central areas during rotary polishing, leading to uneven material removal rates. Second, stress concentration exists at the four corners of square substrates, making them prone to over- or under-removal under polishing pressure. Third, large-sized square substrates are prone to warping during manufacturing and processing, further exacerbating the uneven pressure distribution. Furthermore, as substrate size increases, the weight and dimensions of the bearing head also increase, making the tilting problem between the bearing head and polishing pad due to manufacturing tolerances more prominent, directly affecting the parallelism between the substrate polishing surface and the polishing pad surface.

[0006] Therefore, there is an urgent need to develop a bearing head suitable for large square substrates that can reliably adsorb the square substrate while achieving precise control of the polishing pressure in each area, and solve the tilting problem caused by manufacturing tolerances in large bearing heads, thereby meeting the process requirements for global planarization of square substrates. Summary of the Invention

[0007] In view of this, embodiments of this application provide a bearing head, a chemical mechanical polishing apparatus, and a polishing method to at least partially solve the above-mentioned problems.

[0008] According to a first aspect of the embodiments of this application, a bearing head is provided for chemical mechanical polishing of a square substrate, comprising:

[0009] Coupling disc;

[0010] The upper base is coaxially mounted on the outer periphery of the coupling disk;

[0011] The lower base is connected to the lower part of the upper base;

[0012] A leveling airbag is disposed between the coupling disc and the upper base, and is divided into multiple independent leveling chambers along the circumference. Each leveling chamber is independently pressurized or depressurized to adjust the posture of the upper base and its connected lower base, thereby adjusting the macroscopic parallelism of the square substrate relative to the polishing pad.

[0013] A square flexible membrane, disposed below the lower base, has a square outline adapted to the shape of a square substrate. It contains multiple independent pressurized chambers, including multiple annular chambers in the central region and four corner chambers at the sharp corners. Each corner chamber includes a first sub-chamber and a second sub-chamber separated by an isolation wall. The first sub-chamber is closer to the center of the square outline, and the second sub-chamber is farther from the center of the square outline. The first and second sub-chambers are each connected to an independent gas path interface for independently controlling the gas pressure within each sub-chamber.

[0014] The leveling airbag and the square flexible membrane are controlled separately through independent air paths to achieve macroscopic parallelism adjustment and microscopic pressure distribution control, respectively.

[0015] In some embodiments, the square flexible membrane is further provided with a plurality of vacuum adsorption through holes, which are symmetrically distributed along the diagonal or center line of the square flexible membrane.

[0016] In some embodiments, the isolation wall is concentric arc-shaped, the first sub-chamber is annular, the second sub-chamber is approximately triangular, and the second sub-chamber is formed by the isolation wall and two adjacent side walls of the square flexible membrane.

[0017] In some embodiments, the first sub-chamber is arranged around the second sub-chamber, and another concentric arc-shaped isolation wall is provided between the first sub-chamber and the adjacent annular chamber, the two being arranged adjacent to each other in the radial direction of a square outline.

[0018] In some embodiments, the support head further includes a movable ring disposed between the upper base and the lower base; the movable ring is detachably connected to the upper base, and its outer radial dimension is larger than that of the upper base; the movable ring is provided with a retaining ring, which can be separated and removed from the upper base together with the movable ring while the support head is connected to the polishing shaft.

[0019] In some embodiments, the upper base is further provided with a driving airbag, which is disposed between the upper base and the moving ring, for applying an axial driving force to the moving ring, so that the moving ring reciprocates axially relative to the upper base and the lower base.

[0020] In some embodiments, the movable ring is provided with a guide structure, the guide structure including an intermediate guide shaft and a plurality of V-shaped roller guide rail assemblies, the plurality of V-shaped roller guide rail assemblies being distributed circumferentially along the intermediate guide shaft; each V-shaped roller guide rail assembly includes a mounting body fixed to the movable ring and a V-shaped guide rail fixed to the lower base, a plurality of rollers being provided on opposite sides of the mounting body, the rollers being rotatably mounted on the mounting body, the V-shaped guide rail having a pair of oppositely arranged inclined sides, the rollers abutting against the pair of inclined sides of the V-shaped guide rail for providing guidance and transmitting torque when the movable ring moves axially relative to the lower base.

[0021] In some embodiments, the upper base is provided with an upper limit block, the lower base is provided with a lower limit block, and the moving ring is located between the upper limit block and the lower limit block. The upper limit block and the lower limit block are used to limit the axial movement range of the moving ring.

[0022] According to a second aspect of the embodiments of this application, a chemical mechanical polishing method is provided, using the bearing head described in any of the above claims, comprising the following steps:

[0023] By independently pressurizing or depressurizing each leveling chamber of the leveling airbag, the tilt angle of the lower base relative to the upper base and its connecting components is adjusted so that the polished surface of the square substrate is parallel to the polished surface of the polishing pad.

[0024] After leveling is completed, the polishing pressure of the central and corner areas of the square substrate is controlled by independently pressurizing each pressurizing chamber of the square flexible membrane.

[0025] During the polishing process, the leveling airbag and the square flexible membrane work together. The leveling airbag maintains macroscopic parallelism, while the square flexible membrane adjusts the microscopic pressure distribution.

[0026] In some embodiments, the chemical mechanical polishing method further includes the step of generating a vacuum adsorption force through the vacuum adsorption through-holes of the square flexible film to adsorb and transfer the square substrate.

[0027] According to a third aspect of the embodiments of this application, a chemical mechanical polishing apparatus is provided, which includes a polishing disc, a liquid supply device, a dressing device, and a bearing head as described in any of the above. The bearing head presses a square substrate to be polished against a polishing pad above the polishing disc. The liquid supply device supplies polishing liquid between the polishing pad and the square substrate. The dressing device is used to dress the surface of the polishing pad.

[0028] The beneficial effects of this application include:

[0029] a. This application achieves a two-stage synergy between macroscopic parallelism adjustment and microscopic pressure distribution control by setting up a partitioned pressurization structure of a leveling airbag and a square flexible membrane. The leveling airbag is divided into multiple independent leveling chambers along the circumference. Each chamber is independently pressurized or depressurized to produce local micro-deformation, which can effectively compensate for the tilt caused by manufacturing tolerances of the large bearing head, keeping the polished surface of the square substrate parallel to the polished surface of the polishing pad. On this basis, the square flexible membrane is independently pressurized through the annular chamber located in the central region and the corner chambers located at the four sharp corners, further adjusting the microscopic pressure of each area of ​​the substrate after the leveling airbag has completed macroscopic leveling. The synergistic effect of macroscopic leveling and microscopic pressurization significantly improves the global planarization accuracy of the square substrate.

[0030] b. This application establishes corner chambers at the four sharp corners of a square flexible membrane. Within each corner chamber, concentric arc-shaped partition walls divide it into a ring-shaped sub-chamber near the center and an approximately triangular sub-chamber away from the center. Each sub-chamber is connected to an independent air path interface for independent pressurization control. This structure can precisely compensate for differences in material removal rates caused by variations in rotational linear velocity at different radii within the corner region of the square substrate. It effectively suppresses over-removal or under-removal caused by stress concentration at the corners, improving the polishing uniformity and surface smoothness of the corner region of the square substrate.

[0031] c. This application, by configuring the bearing head as a movable ring detachably connected to the upper base, with the outer radial dimension of the movable ring being larger than that of the upper base, exposes the connecting parts to the outside and allows them to be accessed by operating tools when the bearing head is assembled on the machine. The retaining ring can be separated and removed from the upper base along with the movable ring while the bearing head remains connected to the polishing shaft. This structure allows consumable parts such as the retaining ring and the square flexible diaphragm to be replaced independently without disassembling the entire machine, significantly improving the maintenance convenience of large bearing heads and reducing maintenance costs and time. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings.

[0033] Figure 1 This is a schematic diagram of a carrier head provided in an embodiment of this application;

[0034] Figure 2 yes Figure 1 Longitudinal sectional view of the bearing head;

[0035] Figure 3 yes Figure 2 A magnified view of a section at point A in the middle;

[0036] Figure 4 This is a schematic diagram of a leveling airbag provided in an embodiment of this application;

[0037] Figure 5 This is a cross-sectional view of a leveling airbag provided in an embodiment of this application;

[0038] Figure 6 This is a schematic diagram of the connection between the movable ring and the lower base according to an embodiment of this application;

[0039] Figure 7 yes Figure 6 A schematic diagram of the moving ring in the embodiment;

[0040] Figure 8 yes Figure 6 A schematic diagram of the lower base in the embodiment;

[0041] Figure 9 This is a schematic diagram of the connection between the movable ring and the lower base according to another embodiment of this application;

[0042] Figure 10 yes Figure 9 A schematic diagram of the mounting body and its rollers in the embodiment;

[0043] Figure 11 yes Figure 9 A schematic diagram of the moving ring in the embodiment;

[0044] Figure 12 This is a schematic diagram of a square flexible membrane provided in an embodiment of this application;

[0045] Figure 13 This is a schematic diagram of a square flexible membrane provided in another embodiment of this application;

[0046] Figure 14 This is a cross-sectional view of a square flexible membrane provided in an embodiment of this application;

[0047] Figure 15 This is a pressure stress cloud diagram corresponding to a square flexible membrane provided in an embodiment of this application;

[0048] Figure 16 This is a schematic diagram of a chemical mechanical polishing apparatus provided in an embodiment of this application;

[0049] Figure 17 This is a flowchart of a chemical mechanical polishing method provided in an embodiment of this application. Detailed Implementation

[0050] To enable those skilled in the art to better understand the technical solutions in the embodiments of this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the technical solutions in the embodiments of this application, all other embodiments obtained by those skilled in the art should fall within the protection scope of the embodiments of this application.

[0051] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0052] It should be understood that although the terms "first," "second," "third," etc., may be used in this application to describe various information, this information should not be limited to these terms. These terms are only used to distinguish information of the same type from one another. For example, without departing from the scope of this application, first information may also be referred to as second information, and similarly, second information may also be referred to as first information. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0053] Figure 1 This is a schematic diagram of a carrier head 100 provided in one embodiment of this application. Figure 2 yes Figure 1 A longitudinal sectional view of the bearing head 100. (See attached image.) Figure 1 and Figure 2 As shown, this application embodiment provides a support head 100 for chemical mechanical polishing of square substrates. The support head 100 may include a coupling disk 110, an upper base 120, a lower base 130, a leveling airbag 150, and a square flexible membrane 160. The square substrate may be a large square substrate with dimensions such as 310mm×310mm or 510mm×515mm, or it may be a square substrate of other sizes. That is, the square substrate described in this application includes, but is not limited to, rectangular substrates and square substrates, and its aspect ratio may be 1:1 to 2:1.

[0054] Coupling 110 is used with polishing shaft ( Figure 16 (As shown) The polishing shaft is connected to a drive unit (e.g., an electric motor) that enables the coupling disk 110 and the entire bearing head 100 to rotate about its axis. The coupling disk 110 may be made of metal and may have connecting holes or connecting threads for fixed connection with the polishing shaft.

[0055] The upper base 120 is coaxially disposed on the outer periphery of the coupling disk 110. The upper base 120 can be an annular structure or a disc-shaped structure, with a through hole in its center, through which the coupling disk 110 passes. A leveling airbag 150 is disposed between the upper base 120 and the coupling disk 110. The upper base 120 can be made of metal (e.g., stainless steel) or engineering plastic (e.g., PEEK).

[0056] like Figure 2 As shown, the lower base 130 is disposed below the upper base 120, and a square flexible membrane 160 is disposed below the lower base 130. The lower base 130 can be made of the same or different material as the upper base 120. Various mounting structures can be provided on the upper surface of the lower base 130 for mounting components such as guide shafts and limiting blocks mentioned below.

[0057] In some embodiments, the support head 100 further includes a movable ring 140 disposed between the upper base 120 and the lower base 130. The movable ring 140 is movable axially (i.e., vertically) relative to the upper base 120 and the lower base 130. A retaining ring 141 is provided on the outer edge of the movable ring 140. The retaining ring 141 is used to surround the edge of the square substrate during chemical mechanical polishing to prevent the substrate from flying out of the support head 100. The retaining ring 141 may be made of a wear-resistant material, such as PEEK, PPS, etc., and the lower surface of the retaining ring 141 is in contact with the polishing pad. Preferably, the movable ring 140 is detachably connected to the upper base 120, and the outer radial dimension of the movable ring 140 is larger than the outer radial dimension of the upper base 120, so that the retaining ring 141 can be separated and removed from the upper base 120 together with the movable ring 140 while the bearing head 100 is connected to the polishing shaft. This facilitates the direct replacement of vulnerable parts such as the retaining ring 141 and the square flexible membrane 160 on the whole machine, which significantly improves the maintenance convenience of the large bearing head.

[0058] The leveling airbag 150 is positioned between the coupling plate 110 and the upper base 120. Figure 4 This is a schematic diagram of a leveling airbag provided in one embodiment of this application. Figure 5 This is a cross-sectional view of the leveling airbag. (Example) Figure 4 and Figure 5 As shown, the leveling airbag 150 has a ring-shaped structure and is divided into multiple independent leveling chambers 151 along the circumference. Each leveling chamber 151 is connected to an independent air passage interface, which is used to generate local micro-deformation by independently pressurizing or depressurizing each chamber, so as to adjust the tilt angle of the upper base 120 and its connecting components. The connecting components of the upper base 120 generally include the lower base 130, the moving ring 140, and the square flexible membrane 160.

[0059] Specifically, the leveling airbag 150 has multiple leveling chambers 151 evenly distributed circumferentially. The number of leveling chambers 151 can be selected according to the required leveling accuracy. In some embodiments, the leveling airbag 150 is divided into 8 independent leveling chambers 151 circumferentially. In other embodiments, the leveling airbag 150 is divided into 10 independent leveling chambers 151 circumferentially. In still other embodiments, the leveling airbag 150 is divided into 12 independent leveling chambers 151 circumferentially. The more leveling chambers 151 there are, the higher the leveling accuracy, but the corresponding air path and control complexity also increase. Those skilled in the art can select an appropriate number of leveling chambers according to actual needs.

[0060] The leveling airbag 150 can be made of an elastomer material, such as silicone rubber, fluororubber, or EPDM. Each leveling chamber 151 is separated by a leveling partition wall 152. When a leveling chamber 151 is pressurized, the leveling airbag 150 in that area expands axially, pushing the corresponding area of ​​the upper base 120 upwards; when a leveling chamber 151 is depressurized, the leveling airbag 150 in that area contracts axially, and the corresponding area of ​​the upper base 120 moves downwards under the chamber pressure of the leveling airbag 150. By applying different pressures to different leveling chambers 151, local micro-deformation can be generated, thereby adjusting the tilt angle of the upper base 120, and thus making the polished surface of the square substrate parallel to the polished surface of the polishing pad.

[0061] A square flexible film 160 is disposed below the lower base 130. The square flexible film 160 has a square outline that conforms to the shape of the square substrate. Figure 12 This is a schematic diagram of a square flexible membrane provided in an embodiment of this application. Figure 14 This is a cross-sectional view of a square flexible membrane. (Example) Figures 12 to 14 As shown, the square flexible membrane 160 has multiple independent pressurized chambers 161 inside. The pressurized chambers 161 include multiple annular chambers 162 located in the central region and corner chambers 163 located at the four corners. Each chamber is equipped with an independent air passage interface.

[0062] In this application, the number of annular chambers 162 in the central region can be set according to the size of the square substrate and the pressure zoning requirements. In one embodiment, there are three annular chambers 162 in the central region, namely the first annular chamber, the second annular chamber, and the third annular chamber, arranged concentrically from the center outwards. These three annular chambers 162 respectively cover the central region, the middle region, and the edge region (excluding the corners) of the square substrate. In another embodiment, there are two or four annular chambers 162 to accommodate the pressure control requirements of square substrates of different sizes. Each annular chamber 162 is connected to an external gas source through an independent gas path interface, allowing independent control of the gas pressure within each annular chamber 162.

[0063] like Figure 12 As shown, the corner chambers 163 are located at the four sharp corners of the square flexible membrane 160. Each corner chamber 163 covers a corner area of ​​the square substrate. Each corner chamber 163 is connected to an external air source through an independent air passage interface, allowing independent control of the gas pressure within each corner chamber 163.

[0064] Furthermore, the corner chamber 163 extends in an L-shape at the corner of the square profile. Further, to precisely fit the geometric profile of the corner of the square substrate and effectively cover the stress concentration area in that region, each corner chamber 163 extends in an L-shape at the corresponding corner of the square profile, i.e., it is jointly formed by a first extension 163a and a second extension 163b extending away from the corner along two adjacent sides of that corner. Specifically, each corner chamber 163 includes a first extension 163a and a second extension 163b. The first extension 163a extends a predetermined distance d1 from the starting point of the corner of the square profile along one of its sides in a direction away from the corner. The second extension 163b extends a predetermined distance d2 from the same starting point of the corner along the other adjacent side in a direction away from the corner. The first extension 163a and the second extension 163b are interconnected at the starting point of the corner, so that the corner chamber 163 as a whole presents an L-shaped profile. The first extension 163a and the second extension 163b are flush with the edge of the square flexible membrane 160 on the side near the edge of the square outline, while the side near the center of the square outline is separated from the adjacent annular chamber 162 by the partition wall 165.

[0065] This L-shaped structural design allows the corner chamber 163 to precisely cover the stress concentration areas at the corners of the square substrate. During chemical mechanical polishing, the four corners of the square substrate are the areas with the highest stress concentration. Simultaneously, because the corners are furthest from the rotation center of the bearing head 100, their linear velocity is the highest, and their material removal rate is often higher than other areas of the substrate, easily leading to over-polishing of the corners. The L-shaped extended corner chamber 163, through extensions extending along both sides, achieves independent pressure coverage of the corner area in the two lateral directions. This can more accurately compensate for the differences in material removal rate caused by differences in rotational linear velocity at the corners, thereby suppressing over-polishing or under-polishing of the corners and improving the overall flatness and polishing uniformity of the square substrate.

[0066] The predetermined distance d1 of the first extension 163a extending along its edge and the predetermined distance d2 of the second extension 163b extending along its adjacent edge may be equal or unequal. In one embodiment, d1 and d2 are equal, both being 5% to 15% of the side length of the square substrate. In another embodiment, d1 and d2 are unequal, for example, d1 is 10% of the side length and d2 is 8% of the side length, to provide differentiated compensation for different degrees of warping in the length and width directions of the square substrate. Those skilled in the art can reasonably select the specific values ​​of d1 and d2 based on the size of the square substrate, the degree of warping, the material properties, and the polishing process requirements.

[0067] Figure 13This is a schematic diagram of a square flexible membrane 160 provided in another embodiment of this application. Each corner chamber 163 includes a first sub-chamber 1631 and a second sub-chamber 1632, which are separated by a partition wall 165. The first sub-chamber 1631 is close to the center of the square outline, and the second sub-chamber 1632 is far from the center of the square outline. The first sub-chamber 1631 and the second sub-chamber 1632 are enclosed by the partition wall 165 and the sidewalls of the square flexible membrane 160. The partition wall 165 is concentric arc-shaped, the first sub-chamber 1631 is annular, and the second sub-chamber 1632 is approximately triangular. The approximately triangular second sub-chamber 1632 is enclosed by the concentric arc-shaped partition wall 165 and two adjacent sidewalls of the square flexible membrane 160. The first sub-chamber 1631 and the second sub-chamber 1632 are respectively connected to independent gas passage interfaces for independently controlling the gas pressure in the first sub-chamber 1631 and the second sub-chamber 1632. A first sub-chamber 1631 is arranged around a second sub-chamber 1632, and another partition wall 165 is provided between the first sub-chamber 1631 and the adjacent annular chamber 162. The partition wall 165 between the first sub-chamber 1631 and the adjacent annular chamber 162 is a concentric arc shape, and the first sub-chamber 1631 and the annular chamber 162 are arranged adjacent to each other along the radial direction of the square outline. This structure can finely compensate for the difference in material removal rate caused by the difference in rotational linear velocity at different radii in the corner area of ​​the square substrate, effectively suppressing over-removal or under-removal caused by corner stress concentration.

[0068] Figure 15 This is a pressure stress cloud diagram corresponding to the square flexible membrane 160 provided in an embodiment of this application, which further demonstrates the correction mechanism of substrate warping by the independent back pressure control strategy of the first sub-chamber 1631 and the second sub-chamber 1632.

[0069] In actual polishing processes, square substrates inevitably experience warping due to manufacturing and thinning processes. To address two typical warping patterns, this application employs differentiated back pressures applied through independent air passages in the first sub-chamber 1631 and the second sub-chamber 1632, achieving active warping compensation.

[0070] (a) Convex warping condition (downward bending at four corners, upward convexity at the center): In this case, the four corners of the substrate are in the high-speed polishing stress concentration zone, and the material removal rate at the corners is significantly higher than that in the center area, posing a serious risk of over-polishing. To address this condition, the back pressure is gradually reduced from the center area to the corners. Specifically, a lower pressure is applied to the second sub-chamber 1632 (ultra-high speed zone at the corner tip), and a relatively higher pressure is applied to the first sub-chamber 1631 (medium-low speed transition zone on the inner side of the corner), so that the material removal rate on the inner side of the corner tends to be consistent with that in the center area, avoiding excessive removal at the corner tip due to excessive speed.

[0071] (b) Concave warping condition (center concave, corners upturned): In this case, the contact pressure between the substrate corners and the polishing pad is insufficient, and the material removal rate at the corners is lower than that in the center area, posing a risk of under-polishing. To address this condition, the back pressure is gradually increased from the center area to the corners, i.e., a higher pressure is applied to the second sub-chamber 1632 and a relatively lower pressure is applied to the first sub-chamber 1631, to enhance the adhesion between the corners and the polishing pad and ensure that the material removal rate on the inner side of the corners keeps pace with that in the center area.

[0072] Figure 15 The stress cloud diagram illustrates the pressure distribution of the corresponding areas of the square flexible membrane 160 under the two working conditions described above, using varying shades of color: light-colored areas (such as the position corresponding to the second sub-chamber 1632) represent low-pressure areas, and dark-colored areas (such as the position corresponding to the first sub-chamber 1631) represent high-pressure areas. By independently adjusting the pressure of the first sub-chamber 1631 and the second sub-chamber 1632, active adaptation to the warping shape of the corners of the square substrate is achieved, further improving the global planarization accuracy and polishing uniformity of the square substrate.

[0073] In this preferred embodiment, the partition wall 165 between the L-shaped corner chamber 163 and the adjacent annular chamber 162 is concentrically arc-shaped, forming a smooth pressure transition region between the inner boundary of the corner chamber 163 (i.e., the side closest to the center of the square outline) and the outer boundary of the annular chamber 162. The concentrically arc-shaped partition wall 165 can prevent abrupt pressure changes at the junction of the corner and center regions, thereby forming a continuous and smooth pressure gradient between the corner chamber 163 and the annular chamber 162. Through the synergistic cooperation of the L-shaped corner chamber 163 and the annular chamber 162, especially the independent pressure regulation of the first sub-chamber 1631 and the second sub-chamber 1632 inside the corner chamber 163, fine compensation can be made for the differences in material removal rate caused by the difference in rotational linear velocity at different radii in the corner region of the square substrate. This effectively suppresses over-removal or under-removal caused by stress concentration at the corner, further improving the overall planarization effect of the square substrate.

[0074] During the polishing process, the square substrate rotates around its center. According to kinematic analysis, the linear velocity in the corner region of the square substrate is not uniformly distributed, but increases sharply with the increase of distance from the center of the substrate, thus forming a radial velocity gradient field centered on the corner tip in the corner region.

[0075] This application creatively designs the corner chamber 163 as an annular first sub-chamber 1631 and an approximately triangular second sub-chamber 1632, separated by concentric arc-shaped isolation walls 165. The underlying mechanism lies in the fact that the arcuate trajectory of the concentric arc-shaped isolation walls 165 highly coincides with the theoretical linear velocity contour lines of the corner region of the square substrate during rotary polishing. Specifically, the annular first sub-chamber 1631 covers the medium-to-low speed transition zone inside the corner region, while the approximately triangular second sub-chamber 1632 precisely corresponds to the ultra-high speed stress concentration zone at the outermost end of the corner.

[0076] By configuring independent air paths for the two sub-chambers, decoupled control of the velocity gradient field is achieved: on the one hand, relatively low pressure can be applied to the second sub-chamber 1632 located in the ultra-high speed region to avoid over-polishing (edge ​​collapse) at the corner tip due to excessive linear velocity; on the other hand, relatively high pressure can be applied to the first sub-chamber 1631 located in the transition region to compensate for the back gap caused by warping, ensuring that the material removal rate on the inner side of the corner keeps pace. The synergy of these two approaches breaks the traditional vicious cycle of "the faster the speed, the greater the pressure, and the more severe the over-polishing" at the corners of square substrates.

[0077] In another embodiment, the corner chamber 163 may also be triangular, fan-shaped, or other shapes capable of covering the stress concentration area at the corner of the square substrate, without being limited to an L-shape. The L-shaped structure is merely a preferred embodiment.

[0078] The square flexible membrane 160 is also provided with a plurality of vacuum adsorption through holes 164. The vacuum adsorption through holes 164 are located within 1 / 3 to 2 / 3 of the length of the square flexible membrane 160, and are symmetrically distributed along the diagonal or center line of the square flexible membrane 160. Preferably, the diameter of the vacuum adsorption through holes 164 is 1 mm to 2 mm, and they are distributed at the midpoint of the length of the central region of the square flexible membrane 160. The vacuum degree of the vacuum adsorption through holes 164 is controlled by an external gas source, so that a vacuum adsorption force is generated between the through holes and the square substrate, thereby realizing the adsorption and transport of the square substrate. The vacuum adsorption through holes 164 and the pressurized chamber 161 are spatially isolated from each other to avoid mutual interference between vacuum adsorption and pressurized gas.

[0079] The leveling action of the leveling airbag 150 and the zoned pressurization action of the square flexible membrane 160 are controlled separately through independent air paths. The leveling airbag 150 is used for macroscopic parallelism adjustment—that is, by independently pressurizing or depressurizing each leveling chamber 151, the tilt angle of the entire bearing head is adjusted to keep the polished surface of the square substrate and the polished surface of the polishing pad macroscopically parallel. The square flexible membrane 160 is used for microscopic pressure distribution control—that is, based on macroscopic leveling, the polishing pressure of each region (center region, middle region, edge region, and corner region) of the square substrate is finely adjusted by independently pressurizing each pressurization chamber 161. The synergistic effect of macroscopic leveling and microscopic pressurization significantly improves the overall flatness accuracy of the square substrate.

[0080] Figure 6 This is a schematic diagram showing the connection between the movable ring 140 and the lower base 130 according to an embodiment of this application. Figure 2 As shown, the movable ring 140 is disposed between the upper base 120 and the lower base 130. The upper base 120 is provided with a driving airbag 170, which is disposed between the upper base 120 and the movable ring 140. The driving airbag 170 is used to apply an axial driving force to the movable ring 140, causing the movable ring 140 to reciprocate axially relative to the upper base 120 and the lower base 130.

[0081] The driving airbag 170 has a ring-shaped structure with a pressurizable chamber inside. The upper surface of the driving airbag 170 is in contact with or fixedly connected to the lower surface of the upper base 120, and the lower surface of the driving airbag 170 is in contact with or fixedly connected to the upper surface of the moving ring 140. When the driving airbag 170 is pressurized, the airbag expands axially, pushing the moving ring 140 downward; when the driving airbag 170 is depressurized, the moving ring 140 moves upward under the pressure of the chamber of the driving airbag 170. The maximum stroke of the driving airbag 170 is 10 mm.

[0082] Figure 7 yes Figure 6 A schematic diagram of the moving ring in the embodiment. (See diagram below.) Figure 7 As shown, the central part of the moving ring 140 has a star-shaped rib structure 142. The star-shaped rib structure 142 extends radially from the center of the moving ring 140, forming multiple fan-shaped cavities. The star-shaped rib structure 142 can ensure the structural strength of the moving ring 140, reduce the weight of the moving ring 140, and also provide installation space for other components (such as guide shafts, V-shaped roller guide rail assemblies, etc.).

[0083] Figure 8 yes Figure 6 A schematic diagram of the lower base 130 in the embodiment. (See diagram below.) Figure 8As shown, a groove 131 is provided at a corresponding position on the lower base 130 to cooperate with the star-shaped rib structure 142 of the moving ring 140, thereby achieving vertical movement and compressing the vertical height of the bearing head 100. The shape of the groove 131 matches the star-shaped rib structure 142 of the moving ring 140, so that when the moving ring 140 moves vertically relative to the lower base 130, the star-shaped rib structure 142 can extend into the groove 131, thereby achieving a larger axial stroke without increasing the overall height of the bearing head 100.

[0084] In one embodiment, the moving ring 140 is provided with a guide structure, which includes two guide shafts 181 and two bushings 182. The two guide shafts 181 are fixedly disposed on the lower base 130, and the two bushings 182 are fixedly disposed on the moving ring 140 and respectively sleeved on the outside of the two guide shafts 181. The two guide shafts 181 are used to simultaneously provide axial guidance and transmit torque.

[0085] Specifically, the guide shaft 181 is a cylindrical rod, its lower end fixed in the groove 131 of the lower base 130, and its upper end extending axially. The bushing 182 is a cylindrical component, fixed to the rib structure 142 of the moving ring 140, and sleeved on the outside of the guide shaft 181. The inner diameter of the bushing 182 matches the outer diameter of the guide shaft 181, allowing the bushing 182 to slide axially along the guide shaft 181. The fit between the guide shaft 181 and the bushing 182 can be a sliding bearing fit or a linear bearing fit. When the moving ring 140 moves axially relative to the lower base 130, the bushing 182 slides along the guide shaft 181, ensuring the axial movement accuracy of the moving ring 140. Meanwhile, when the bearing head 100 rotates, the upper base 120 rotates as the driving element under the drive of the coupling disc 110; the upper base 120 also transmits torque to the moving ring 140 by friction through the driving airbag 170 set between the upper base 120 and the moving ring 140, so as to drive the moving ring 140 to rotate synchronously; the cooperation between the guide shaft 181 and the bushing 182 is used to provide guidance when the moving ring 140 moves axially relative to the lower base 130, and to assist in transmitting torque to ensure that the moving ring 140 and the lower base 130 rotate synchronously.

[0086] In another embodiment, the moving ring 140 is provided with another form of guide structure, such as Figure 9 As shown, the guide structure includes a central guide shaft 183 and a V-shaped roller guide rail assembly 184. The central part of the moving ring 140 has a cross-shaped rib structure 143. The cross-shaped rib structure 143 extends from the center of the moving ring 140 in four directions, forming four fan-shaped cavities. The cross-shaped rib structure 143 ensures the structural strength of the moving ring 140 while reducing its weight.

[0087] Figure 10 yes Figure 9 A schematic diagram of the mounting body 185 and its rollers 187 in the embodiment. Figure 11 yes Figure 9 A schematic diagram of the moving ring 140 in the embodiment. (See diagram below.) Figures 9 to 11 As shown, the intermediate guide shaft 183 is disposed in the central region of the moving ring 140. The intermediate guide shaft 183 is a cylindrical rod, the lower end of which is fixed to the center of the lower base 130, and the upper end extends axially. The intermediate guide shaft 183 is used to provide axial guidance. The center of the moving ring 140 is provided with a guide hole that matches the intermediate guide shaft 183. The moving ring 140 is sleeved on the outside of the intermediate guide shaft 183 through the guide hole and can slide back and forth axially along the intermediate guide shaft 183.

[0088] There are multiple V-shaped roller guide assemblies 184, which are distributed circumferentially along the central guide shaft 183. In one embodiment, there are four V-shaped roller guide assemblies 184, evenly distributed circumferentially along the central guide shaft 183. Each V-shaped roller guide assembly 184 includes a mounting body 185 fixed to the moving ring 140 and a V-shaped guide rail 186 fixed to the lower base 130.

[0089] Mounting bodies 185 are disposed on the rib structure of the movable ring 140, such as a star-shaped rib structure 142 or a cross-shaped rib structure 143. Multiple rollers 187 are provided on opposite sides of the mounting body 185, and the rollers 187 are rotatably mounted on the mounting body 185. In one embodiment, the mounting body 185 is an inverted U-shaped structure, with the rollers 187 disposed on both sides of the mounting body 185. A pin 188 is provided on the mounting body 185, and the rollers 187 are sleeved on the outside of the pin 188 and can rotate around the pin 188. Each mounting body 185 has 4 to 12 rollers 187 arranged at vertical intervals.

[0090] V-shaped guide rail 186 is fixed to the lower base 130. V-shaped guide rail 186 has a pair of opposing inclined sides 189. The pair of inclined sides 189 of V-shaped guide rail 186 are arranged in a V-shape, with an included angle of 30° to 45° between them. Roller 187 abuts against the pair of inclined sides 189 of V-shaped guide rail 186 to provide guidance and transmit torque as the moving ring 140 moves axially relative to the lower base 130.

[0091] The V-shaped guide rail 186 is located between the two sides of the mounting body 185, and the rollers 187 on both sides of the mounting body 185 abut against the two outer or inner inclined surfaces of the V-shaped guide rail 186, respectively. Specifically, when the mounting body 185 is an inverted U-shaped structure, the V-shaped guide rail 186 is located within the opening of the U-shaped structure, and the rollers 187 on both sides of the mounting body 185 abut against the two outer inclined surfaces of the V-shaped guide rail 186, respectively. When the moving ring 140 moves axially relative to the lower base 130, the rollers 187 roll along the inclined side surface 189 of the V-shaped guide rail 186, converting sliding friction into rolling friction, significantly reducing frictional resistance. At the same time, the pair of inclined side surfaces 189 of the V-shaped guide rail 186 constrain the rollers 187 from both sides, limiting the horizontal displacement of the moving ring 140 and ensuring the motion accuracy of the moving ring 140. Furthermore, when the bearing head 100 rotates, the upper base 120 rotates as the driving element under the drive of the coupling disc 110; the upper base 120 also transmits torque to the moving ring 140 by pressing the drive airbag 170 disposed between the upper base 120 and the moving ring 140 through friction, thereby driving the moving ring 140 to rotate; at the same time, the moving ring 140 and the lower base 130 transmit torque to each other through the roller 187 abutting against the inclined side 189 of the V-shaped guide rail 186, so that the moving ring 140 and the lower base 130 rotate synchronously.

[0092] In one embodiment, the upper base 120 is provided with an upper limit block 191, the lower base 130 is provided with a lower limit block 192, and the moving ring 140 is located between the upper limit block 191 and the lower limit block 192. Figure 2 and Figure 3 As shown. The upper limit block 191 and the lower limit block 192 are used to limit the axial movement range of the moving ring 140. Figure 3 In this structure, the upper limit block 191 is fixed to the lower surface of the upper base 120 and extends downward. The lower limit block 192 is fixed to the upper surface of the lower base 130 and extends upward. The moving ring 140 is disposed between the upper limit block 191 and the lower limit block 192. When the moving ring 140 moves upward to the upper limit position, the upper surface of the moving ring 140 abuts against the lower surface of the upper limit block 191, preventing the moving ring 140 from moving further upward. When the moving ring 140 moves downward to the lower limit position, the lower surface of the moving ring 140 abuts against the upper surface of the lower limit block 192, preventing the moving ring 140 from moving further downward. The upper limit block 191 and the lower limit block 192 together limit the axial movement range of the moving ring 140, preventing the moving ring 140 from exceeding the preset stroke and ensuring the safety of the bearing head 100.

[0093] The upper limit block 191 and the lower limit block 192 can be made of metal or wear-resistant engineering plastic. The surfaces of the upper limit block 191 and the lower limit block 192 that contact the moving ring 140 can be provided with buffer pads, such as rubber pads, to buffer the impact between the moving ring 140 and the limit blocks.

[0094] Figure 16 This is a schematic diagram of a chemical mechanical polishing apparatus provided in one embodiment of this application. Figure 16 As shown, the chemical mechanical polishing (CMP) apparatus 1000 includes a polishing disc 200, a liquid supply device 300, a dressing device 400, and a support head 100 as described in any of the above embodiments. A polishing pad 210 is disposed above the polishing disc 200. The support head 100 presses the square substrate to be polished against the polishing pad 210 above the polishing disc 200. The liquid supply device 300 supplies polishing liquid between the polishing pad 210 and the square substrate. The dressing device 400 is used to dress the surface of the polishing pad 210.

[0095] The polishing disc 200 is connected to a drive motor (not shown in the figure) and can rotate around its axis under the drive of the drive motor. A polishing pad 210 is attached to the upper surface of the polishing disc 200, and the upper surface of the polishing pad 210 constitutes the polishing surface. The polishing pad 210 can be made of commonly used polishing pad materials in the art, such as polyurethane polishing pads or non-woven fabric polishing pads.

[0096] The liquid supply device 300 includes a liquid supply pipe and a liquid supply nozzle. One end of the liquid supply pipe is connected to a polishing liquid source (not shown in the figure), and the other end is connected to the liquid supply nozzle. The liquid supply nozzle is positioned above the polishing pad 210 and sprays polishing liquid between the polishing pad 210 and the square substrate. The polishing liquid may contain abrasive particles (e.g., silica, cerium oxide, etc.) and chemical reagents (e.g., pH adjusters, oxidants, etc.).

[0097] The dressing device 400 includes a dressing arm and a dressing head. One end of the dressing arm is connected to a drive device (not shown), and the other end is connected to the dressing head. A dressing element (e.g., diamond particles) is provided on the lower surface of the dressing head. The dressing device 400 is used to dress the surface of the polishing pad 210 during or between polishing processes, removing residues and polishing byproducts from the surface of the polishing pad 210, and restoring the roughness and polishing performance of the polishing pad 210.

[0098] Figure 17 This is a flowchart of a chemical mechanical polishing method provided in an embodiment of this application. The chemical mechanical polishing method includes the following steps.

[0099] Step S100: Vacuum adsorption force is generated through the vacuum adsorption through-holes 164 of the square flexible film 160 to adsorb the square substrate.

[0100] Specifically, when loading the square substrate, a vacuum is applied to the vacuum adsorption through-hole 164 of the square flexible film 160 by an external air source, so that a vacuum adsorption force is generated between the vacuum adsorption through-hole 164 and the square substrate, and the square substrate is adsorbed onto the lower surface of the square flexible film 160.

[0101] Step S200: By independently pressurizing or depressurizing each leveling chamber 151 of the leveling airbag 150, the tilt angle of the lower base 130 relative to the upper base 120 is adjusted so that the polished surface of the square substrate is parallel to the polished surface of the polishing pad 210.

[0102] Specifically, after the square substrate is adsorbed onto the square flexible film 160, before polishing begins or in the initial stage of polishing, compressed gas is independently supplied to or discharged from each leveling chamber 151 of the leveling airbag 150 via an external air source. When a leveling chamber 151 is pressurized, the leveling airbag 150 in that area expands axially, pushing the corresponding area of ​​the upper base 120 upward; when a leveling chamber 151 is depressurized, the leveling airbag 150 in that area contracts axially, and the corresponding area of ​​the upper base 120 moves downward. By controlling the pressure of each leveling chamber 151, the tilt angle of the upper base 120 can be adjusted, and thus the tilt angle of the square substrate can be adjusted via the lower base 130 and the square flexible film 160, so that the polished surface of the square substrate remains macroscopically parallel to the polished surface of the polishing pad 210.

[0103] Step S300: After leveling is completed, the polishing pressure of the central area and corner area of ​​the square substrate is controlled by independently pressurizing each pressurizing chamber 161 of the square flexible membrane 160.

[0104] Specifically, after the leveling airbag 150 completes macroscopic leveling, compressed gas is independently supplied to each pressurized chamber 161 of the square flexible membrane 160 via an external air source. The annular chamber 162 in the central region controls the polishing pressure of the central region, middle region, and edge region (excluding corners) of the square substrate. The corner chambers 163 control the polishing pressure of the four corners of the square substrate. The first sub-chamber 1631 and the second sub-chamber 1632 of each corner chamber 163 are independently pressurized to achieve pressure gradient control at different radial positions in the corner region, thereby more precisely compensating for differences in material removal rate caused by differences in rotational linear velocity at the corners. The pressure of each pressurized chamber 161 can be independently adjusted according to the material, thickness, warpage degree, and polishing process requirements of the square substrate. For example, for a square substrate with significant warpage, the polishing pressure in the central region can be appropriately increased; for a square substrate with stress concentration at the corners, the polishing pressure in the corner regions can be appropriately decreased or increased. Through independent pressurization of each pressurized chamber 161, precise control of the polishing pressure in each region of the square substrate is achieved.

[0105] Step S400: During the polishing process, the leveling airbag 150 and the square flexible membrane 160 work together. The leveling airbag 150 maintains macroscopic parallelism, and the square flexible membrane 160 adjusts the microscopic pressure distribution.

[0106] Specifically, during the polishing process, the parallelism between the polished surface of the square substrate and the polished surface of the polishing pad 210 may change due to factors such as wear of the polishing pad 210, vibration of the bearing head 100, and temperature changes. The leveling airbag 150 dynamically maintains the macroscopic parallelism between the square substrate and the polishing pad 210 by adjusting the pressure of each leveling chamber 151 in real time. At the same time, the square flexible membrane 160 adjusts the microscopic pressure distribution in each area of ​​the square substrate in real time by independently pressurizing each pressurizing chamber 161. The leveling airbag 150 and the square flexible membrane 160 work together to ensure the overall flattening accuracy of the square substrate.

[0107] After polishing is completed, stop applying vacuum or apply positive pressure to release the vacuum adsorption force and release the square substrate from the square flexible film 160.

[0108] The vacuum adsorption through-hole 164 and the pressurized chamber 161 of the square flexible film 160 are spatially isolated from each other. The vacuum adsorption through-hole 164 is used to achieve the adsorption and transport of the square substrate, while the pressurized chamber 161 is used to apply polishing pressure to the square substrate during the polishing process. The two have different functions, and their spatial isolation avoids mutual interference.

[0109] The working process of the support head 100 is as follows: First, a vacuum is applied through the vacuum adsorption through-hole 164 of the square flexible membrane 160, adsorbing the square substrate onto the lower surface of the square flexible membrane 160. Then, by independently pressurizing or depressurizing each leveling chamber 151 of the leveling airbag 150, the tilt angle of the square substrate is adjusted so that the polished surface of the square substrate is parallel to the polished surface of the polishing pad 210. Next, the support head 100 is lowered so that the polished surface of the square substrate contacts the polished surface of the polishing pad 210. By independently pressurizing each pressurizing chamber 161 of the square flexible membrane 160, the polishing pressure of each area of ​​the square substrate is controlled. The rotation of the polishing disk 200 and the support head 100 is started to begin chemical mechanical polishing. During the polishing process, the leveling airbag 150 and the square flexible membrane 160 work together to maintain macroscopic parallelism and adjust the microscopic pressure distribution. After polishing is completed, rotation is stopped, the support head 100 is raised, the vacuum adsorption is released, and the square substrate is removed from the support head 100.

[0110] The carrier head 100, square flexible membrane 160, chemical mechanical polishing equipment, and chemical mechanical polishing method provided in this application embodiment achieve macroscopic parallelism adjustment through the leveling airbag 150 and microscopic pressure distribution control through the square flexible membrane 160. The synergistic effect of these two components significantly improves the overall planarization accuracy of the square substrate. By setting corner chambers 163 at the four sharp corners of the square flexible membrane 160, and within each corner chamber 163, setting an annular first sub-chamber 1631 and an approximately triangular second sub-chamber 1632 separated by concentric arc-shaped isolation walls, finer pressure control is achieved in the corner areas of the square substrate, effectively suppressing over-removal or under-removal caused by corner stress concentration. Furthermore, by detachably connecting the moving ring 140 to the upper base 120, and ensuring that the outer radial dimension of the moving ring 140 is larger than that of the upper base 120, the retaining ring 141 can be independently replaced without changing the connection state between the carrier head and the polishing shaft, significantly improving the maintenance convenience of the large carrier head.

[0111] Those skilled in the art will recognize that the units and method steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this application.

[0112] The above embodiments are only used to illustrate the embodiments of this application, and are not intended to limit the embodiments of this application. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the embodiments of this application. Therefore, all equivalent technical solutions also fall within the scope of the embodiments of this application, and the patent protection scope of the embodiments of this application should be defined by the claims.

Claims

1. A bearing head for chemical mechanical polishing of a square substrate, characterized in that, include: Coupling disc; The upper base is coaxially mounted on the outer periphery of the coupling disk; The lower base is connected to the lower part of the upper base; A leveling airbag is disposed between the coupling disc and the upper base, and is divided into multiple independent leveling chambers along the circumference. Each leveling chamber is independently pressurized or depressurized to adjust the posture of the upper base and its connected lower base, thereby adjusting the macroscopic parallelism of the square substrate relative to the polishing pad. A square flexible membrane, disposed below the lower base, has a square outline adapted to the shape of a square substrate. It contains multiple independent pressurized chambers, including multiple annular chambers in the central region and four corner chambers at the sharp corners. Each corner chamber includes a first sub-chamber and a second sub-chamber separated by an isolation wall. The first sub-chamber is closer to the center of the square outline, and the second sub-chamber is farther from the center of the square outline. The first and second sub-chambers are each connected to an independent gas path interface for independently controlling the gas pressure within each sub-chamber. The leveling airbag and the square flexible membrane are controlled separately through independent air paths to achieve macroscopic parallelism adjustment and microscopic pressure distribution control, respectively.

2. The bearing head according to claim 1, characterized in that, The square flexible membrane is also provided with multiple vacuum adsorption through holes, which are symmetrically distributed along the diagonal or center line of the square flexible membrane.

3. The bearing head according to claim 1, characterized in that, The isolation wall is concentric arc-shaped, the first sub-chamber is annular, and the second sub-chamber is approximately triangular. The second sub-chamber is formed by the isolation wall and two adjacent side walls of the square flexible membrane.

4. The bearing head according to claim 3, characterized in that, The first sub-chamber is arranged around the second sub-chamber, and another concentric arc-shaped isolation wall is provided between the first sub-chamber and the adjacent annular chamber. The two are arranged adjacent to each other along the radial direction of the square outline.

5. The bearing head according to claim 1, characterized in that, The bearing head also includes a movable ring disposed between the upper base and the lower base; the movable ring is detachably connected to the upper base, and its outer radial dimension is larger than that of the upper base; the movable ring is provided with a retaining ring, which can be separated and removed from the upper base together with the movable ring while the bearing head is connected to the polishing shaft.

6. The bearing head according to claim 5, characterized in that, The upper base is also provided with a driving airbag, which is disposed between the upper base and the moving ring, for applying an axial driving force to the moving ring, so that the moving ring reciprocates axially relative to the upper base and the lower base.

7. The bearing head according to claim 5, characterized in that, The moving ring is provided with a guide structure, which includes an intermediate guide shaft and multiple V-shaped roller guide rail assemblies. The multiple V-shaped roller guide rail assemblies are distributed circumferentially along the intermediate guide shaft. Each V-shaped roller guide rail assembly includes a mounting body fixed to the moving ring and a V-shaped guide rail fixed to the lower base. Multiple rollers are provided on opposite sides of the mounting body. The rollers are rotatably mounted on the mounting body. The V-shaped guide rail has a pair of oppositely arranged inclined sides. The rollers abut against the pair of inclined sides of the V-shaped guide rail to provide guidance and transmit torque when the moving ring moves axially relative to the lower base.

8. The bearing head according to claim 5, characterized in that, The upper base is provided with an upper limit block, the lower base is provided with a lower limit block, and the moving ring is located between the upper limit block and the lower limit block. The upper limit block and the lower limit block are used to limit the axial movement range of the moving ring.

9. A chemical mechanical polishing method, using the carrier head according to any one of claims 1 to 8, characterized in that, Includes the following steps: By independently pressurizing or depressurizing each leveling chamber of the leveling airbag, the tilt angle of the lower base relative to the upper base and its connecting components is adjusted so that the polished surface of the square substrate is parallel to the polished surface of the polishing pad. After leveling is completed, the polishing pressure of the central and corner areas of the square substrate is controlled by independently pressurizing each pressurizing chamber of the square flexible membrane. During the polishing process, the leveling airbag and the square flexible membrane work together. The leveling airbag maintains macroscopic parallelism, while the square flexible membrane adjusts the microscopic pressure distribution.

10. The chemical mechanical polishing method according to claim 9, characterized in that, It also includes the step of generating vacuum adsorption force through the vacuum adsorption through-holes of the square flexible film to adsorb and transport the square substrate.

11. A chemical mechanical polishing apparatus, characterized in that, The device includes a polishing disc, a liquid supply device, a trimming device, and a bearing head as described in any one of claims 1 to 8. The bearing head presses a square substrate to be polished against a polishing pad above the polishing disc. The liquid supply device supplies polishing liquid between the polishing pad and the square substrate. The trimming device is used to trim the surface of the polishing pad.

Images