Polishing method, polishing device and silicon wafer

Abstract

Embodiments of the present disclosure provide a polishing method, a polishing device, and a silicon wafer. The polishing method comprises: holding a silicon wafer using a polishing head, such that when the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed, and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head; and adjusting a temperature of the pad assembly, so as to deform the pad assembly to at least partially conform to the second surface of the held silicon wafer, such that, during polishing, pressure on the pad assembly is transmitted to the silicon wafer via the part that conforms to the second surface of the silicon wafer.

Description

Polishing methods, polishing equipment and silicon wafers

[0001] Cross-reference to related applications

[0002] This disclosure claims priority to Chinese Patent Application No. 202411582864.9, filed in China on November 7, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to the field of silicon wafer processing technology, and more particularly to polishing methods, polishing equipment, and silicon wafers. Background Technology

[0004] In the semiconductor manufacturing industry, with the advancement of technology, the requirements for the surface flatness of silicon wafers are becoming increasingly stringent. To improve the surface flatness of silicon wafers, the manufacturing process typically includes two key steps: double-sided polishing and final polishing. In double-sided polishing, both the front and back sides of the silicon wafer are polished, while in final polishing, the focus is on polishing the front side of the silicon wafer.

[0005] During the final polishing process, the silicon wafer is adsorbed onto the polishing head and pressed onto a polishing pad located below the head. Through the action of the polishing pad, the front side of the silicon wafer undergoes fine polishing. The amount of material removed during this process has a decisive impact on the flatness of the silicon wafer after polishing, especially the overall and edge flatness. Furthermore, the morphology of the silicon wafer before final polishing also affects the flatness after final polishing.

[0006] Currently, in continuous processing, the impact of morphological differences between different silicon wafers before final polishing on the final polishing effect is not fully considered. Instead, the same process parameters are used to process different silicon wafers uniformly. This undifferentiated processing often results in polished silicon wafers that cannot meet precise size and shape requirements.

[0007] Therefore, customizing polishing process parameters based on the expected size and shape after polishing and the specific morphology of each silicon wafer before final polishing is of significant importance for improving the overall quality of silicon wafer manufacturing. Summary of the Invention

[0008] In view of this, embodiments of the present disclosure aim to provide a polishing method, polishing equipment, and silicon wafer. By using this polishing method, the distribution of pressure applied to the silicon wafer can be precisely controlled by the deformation of the pad assembly with temperature, so as to customize the amount of material removed according to the expected size and shape of the silicon wafer and the specific morphology of the silicon wafer before polishing, thereby achieving the desired polishing effect.

[0009] The technical solution of this disclosure embodiment is implemented as follows:

[0010] In a first aspect, embodiments of this disclosure provide a polishing method, the polishing method comprising:

[0011] A silicon wafer is held by a polishing head, wherein, while the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head;

[0012] The pad assembly is temperature-regulated to deform it into at least partially conforming to the second surface of the held silicon wafer, so that during polishing, the pressure on the pad assembly is transmitted to the silicon wafer via the portion conforming to the second surface of the silicon wafer.

[0013] In some alternative examples, the pad assembly includes a plurality of deformable regions capable of deforming independently of each other, and the temperature conditioning of the pad assembly includes independently conditioning the temperature of each of the plurality of deformable regions of the pad assembly.

[0014] In some optional examples, the temperature regulation of the pad assembly includes: independently heating one or more target deformable regions of the plurality of deformable regions of the pad assembly.

[0015] In some optional examples, the temperature conditioning of the pad assembly includes: determining one or more target deformable regions from the plurality of deformable regions of the pad assembly based on the topography of the first surface of the held silicon wafer.

[0016] In some alternative examples, the pad assembly includes a pad body and an adsorption pad for adsorbing silicon wafers, bonded to the pad body.

[0017] Accordingly, the temperature conditioning of the pad assembly to deform the pad assembly into at least partially conforming to the second surface of the held silicon wafer includes: temperature conditioning the pad body to deform the pad body and the adsorption pad deforms with the deformation of the pad body into at least partially conforming to the second surface of the held silicon wafer.

[0018] In a second aspect, embodiments of this disclosure provide a polishing apparatus for performing the polishing method according to the first aspect, the polishing apparatus comprising:

[0019] A polishing head for holding a silicon wafer, wherein, when the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head;

[0020] A temperature control module is provided for temperature regulation of the pad assembly to deform the pad assembly into at least partially contacting the second surface of the held silicon wafer, so that during polishing, the pressure on the pad assembly is transmitted to the silicon wafer via the portion of the pad assembly that is in contact with the second surface of the silicon wafer.

[0021] In some alternative examples, the gasket assembly includes a plurality of deformable regions capable of deforming independently of each other, and the temperature control module includes a plurality of temperature control units configured to independently adjust the temperature of each of the plurality of deformable regions of the gasket assembly.

[0022] In some alternative examples, at least a portion of the plurality of temperature-regulating sections are disposed at different positions in the radial direction of the held silicon wafer.

[0023] In some alternative examples, the plurality of temperature-regulating sections are arranged in a plurality of annular shapes concentrically with the silicon wafer being held.

[0024] In some alternative examples, the pad assembly includes a pad body and an adsorption pad for adsorbing silicon wafers, bonded to the pad body.

[0025] The temperature control module is configured to adjust the temperature of the pad body to deform the pad body, and the adsorption pad is configured to deform with the deformation of the pad body to at least partially conform to the second surface of the held silicon wafer.

[0026] Thirdly, embodiments of this disclosure provide a silicon wafer obtained by using a polishing method according to any one of claims 1 to 5, wherein the total thickness deviation of the silicon wafer is less than 100 nanometers and the local flatness is less than 20 nanometers.

[0027] Some embodiments of this disclosure provide a polishing method. This polishing method includes: while a silicon wafer is held by a polishing head, precisely controlling the shape of a pad assembly of the polishing head through temperature regulation, so that the pad assembly adheres to the silicon wafer at a predetermined position, thereby achieving customized control of the pressure distribution in different areas of the silicon wafer during the polishing process. This customized pressure distribution further enables customized distribution of material removal. Since the predetermined position where the pad assembly adheres to the silicon wafer can be determined based on the target morphology of the silicon wafer and its initial morphology before polishing, this polishing method can precisely control the material removal distribution of each silicon wafer during the polishing process through precise pressure regulation to meet the specific needs of each silicon wafer, ultimately obtaining a silicon wafer with a desired morphology. Attached Figure Description

[0028] Figure 1 is a schematic diagram of the polishing equipment provided in an embodiment of this disclosure;

[0029] Figure 2 is a flowchart of the polishing method provided in an embodiment of this disclosure;

[0030] Figure 3 is a schematic diagram of a polishing apparatus provided in another embodiment of this disclosure;

[0031] Figure 4 is a schematic diagram of the polishing head provided in an embodiment of this disclosure;

[0032] Figure 5 is another schematic diagram of the polishing head shown in Figure 4;

[0033] Figure 6 is a schematic diagram of a portion of the polishing head provided in an embodiment of this disclosure;

[0034] Figure 7 is a schematic diagram of a portion of a polishing head provided in another embodiment of this disclosure;

[0035] Figure 8 is a schematic diagram of a polishing head provided in another embodiment of this disclosure. Detailed Implementation

[0036] The technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings.

[0037] Microscopic damage and stress concentration may be introduced into the silicon wafer surface during early processing steps such as cutting and grinding. The final polishing process can remove these microscopic defects, thereby improving the surface flatness of the silicon wafer.

[0038] Figure 1 illustrates a polishing apparatus 10 provided in some embodiments of the present disclosure. The polishing apparatus 10 may include: a polishing table 11, a polishing pad 12 disposed on the upper surface of the polishing table 11, and a drive shaft 13 disposed below the polishing table 11. The polishing pad 12 can rotate together with the polishing table 11 under the drive of the drive shaft 13. For example, when the polishing table 11 rotates clockwise under the drive of the drive shaft 13, the polishing pad 12 also rotates counterclockwise.

[0039] Furthermore, a polishing head 14 is disposed above the polishing table 11. The polishing head 14 may include at least: a head body 141, a rotary drive 142 connected to the head body 141, and an assembly mold 143 disposed below the head body 141. A rubber pad 144 is placed within a first receiving cavity CS1 formed by the assembly mold 143. The silicon wafer S to be polished is also housed within the first receiving cavity CS1. The rubber pad 144 can be connected to the head body 141. Compressed dry air is supplied to the first receiving cavity CS1 of the assembly mold 143 via a vacuum / air pipe 145 to create working pressure. This working pressure acts on the rubber pad 144 and is transmitted to the silicon wafer S to be polished via the rubber pad 144.

[0040] The head body 141 can be driven by the rotary drive 142 to rotate, so that the head body 141 and the silicon wafer S housed in the first receiving cavity CS1 of the assembly mold 143 can also rotate with the rotation of the head body 141. For example, when the rotary drive 142 rotates counterclockwise, the head body 141 and the silicon wafer S to be polished also rotate counterclockwise.

[0041] The polishing apparatus 10 may also include a nozzle 15 disposed in the space above the polishing pad 12 and close to the center of the polishing pad 12. The nozzle 15 may be connected to a storage tank (not shown) for storing polishing liquid, and the dripping flow rate of the polishing liquid may be controlled by a valve.

[0042] During the polishing operation, the rotating polishing head 14 presses the silicon wafer onto the rotating polishing pad 12 under a certain working pressure. A polishing slurry, composed of submicron or nano-abrasive particles and a chemical solution, drips onto the polishing pad 12 through nozzle 15. The polishing slurry is then uniformly distributed on the polishing pad 12 under the influence of transport and centrifugal force. During distribution, the polishing slurry flows between the surface of the silicon wafer S and the polishing pad 12, forming a thin film of polishing slurry between them. The chemical components in the polishing slurry can react with the surface material of the silicon wafer, converting insoluble substances into soluble substances or softening hard substances. These chemical reactants are then removed from the silicon wafer surface by the micromechanical friction of the abrasive particles, dissolved in the flowing slurry and carried away. This alternating process of chemical film formation and mechanical film removal achieves planarization.

[0043] The inventors noted that, for the aforementioned polishing apparatus 10, since the pressure of the grinding head is transmitted vertically to the silicon wafer S to be polished via a single rubber pad 144, the amount of material removed from each area of ​​the entire polished surface of the silicon wafer S is essentially uniform. However, in actual production, due to various factors present in the preceding processing, different silicon wafers exhibit differences in morphology and flatness before final polishing. In this case, if a uniform material removal scheme is still adopted for each silicon wafer during polishing, the polished silicon wafer may not meet the target morphology requirements.

[0044] Based on this, the inventors, after research, concluded that in order to achieve the target morphology requirements after polishing, it is necessary to set a material removal amount distribution scheme specifically for each silicon wafer, taking into account both the target morphology and the initial morphology before polishing. In other words, for a single silicon wafer, a uniform material removal amount should no longer be set for every region on its polished surface; instead, a corresponding material removal amount should be set based on the specific conditions of different regions. Furthermore, for different silicon wafers, a uniform material removal amount distribution scheme should no longer be used; instead, a corresponding material distribution scheme should be adopted based on the target morphology and initial morphology of each silicon wafer.

[0045] Through further research, the inventors discovered that material removal during the polishing process primarily relies on the friction generated between the abrasive particles in the polishing slurry and the silicon wafer surface. As the pressure applied to the silicon wafer increases, both the contact area and contact strength between the abrasive particles and the wafer surface increase, allowing the abrasive particles to embed more extensively and deeply into the wafer surface, thereby removing more material. Therefore, the inventors believe that if the polishing head can apply different pressures to different areas of the same silicon wafer during the polishing process, the amount of material removed from different areas of the wafer can vary, thus obtaining a silicon wafer that meets the target morphology requirements.

[0046] In view of the above, the present disclosure provides a polishing method, polishing equipment, and silicon wafer. By using this polishing method, the distribution of pressure applied to the silicon wafer can be precisely controlled by the deformation of the pad assembly with temperature, allowing for customized adjustment of the material removal amount based on the expected size and shape of the silicon wafer and its specific morphology before polishing, thereby achieving the desired polishing effect.

[0047] The embodiments of this disclosure are described in detail below with reference to the accompanying drawings.

[0048] Referring to Figure 2, some embodiments of this disclosure provide a polishing method, which includes:

[0049] S101: A silicon wafer is held with a polishing head, wherein, when the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head;

[0050] S102: Temperature-regulate the pad assembly to deform it into at least partially conforming to the second surface of the held silicon wafer, so that during polishing, the pressure on the pad assembly is transmitted to the silicon wafer via the portion conforming to the second surface of the silicon wafer.

[0051] Referring to Figure 3, some embodiments of this disclosure also provide a polishing apparatus 100. The polishing apparatus 100 may include a polishing head 200, as shown in Figure 4. The polishing method of Figure 1 will now be described in detail with reference to the polishing apparatus 100 and the polishing head 200.

[0052] A polishing head 200 is used to hold a silicon wafer S, exposing a first surface S1 of the wafer S. The polishing head 200 may include a pad assembly 21 and a temperature control module 22. The pad assembly 21 may be configured within the polishing head 200 such that, when the silicon wafer is held by the polishing head 200, the pad assembly 21 is adjacent to a second surface S2 of the held silicon wafer S, wherein the first surface S1 is opposite to the second surface S2. The temperature control module 22 may be configured to regulate the temperature of the pad assembly 21, causing the pad assembly 21 to deform into a shape that at least partially adheres to the second surface S2 of the held silicon wafer S, so that during polishing, the pressure on the pad assembly 21 can be transmitted to the silicon wafer S via the portion of the pad assembly 21 that adheres to the second surface S2 of the silicon wafer S.

[0053] As shown in Figure 2, the polishing head 200 may include a body 23 and a retaining portion 24 extending from one surface of the body 23. When the polishing head 200 is in use, the retaining portion 24 is located on the lower surface of the body 23 and may be generally annular to form a downwardly open chamber 25 with the body 23 to accommodate the silicon wafer S therein.

[0054] In various embodiments of this disclosure, one of the first surface S1 and the second surface S2 of the silicon wafer refers to the front side of the silicon wafer, and the other refers to the back side of the silicon wafer. When the silicon wafer S is housed in the chamber 25, the first surface S1 to be polished is exposed to the surrounding environment, while the second surface S2 faces the body 23.

[0055] The surface of the pad assembly 21 adjacent to the second surface S2 of the silicon wafer S can have a shape and size corresponding to the second surface S2. The pad assembly 21 can also be disposed in the chamber 25, and the temperature control module 22 can be disposed between the body 23 and the pad assembly 21. The temperature control module 22 can be disposed adjacent to the pad assembly 21 or in direct contact with the pad assembly 21 to transfer its own temperature to the pad assembly 21 via air or directly.

[0056] The temperature control module 22 can be configured to at least partially regulate the temperature of the pad assembly 21. In some embodiments of this disclosure, the temperature control module 22 is configured to regulate the temperature of any area on the surface of the pad assembly 21 adjacent to the temperature control module 22.

[0057] The pad assembly 21 can be made of a material that can deform upon heating. In some embodiments of this disclosure, the pad assembly 21 can be made of a material that undergoes significant shape change but small volume change upon heating, such as a shape memory alloy or shape memory polymer. In this case, to prevent the pad assembly 21 from damaging the second surface S2 of the silicon wafer S, the pad assembly 21 may include a deformable pad body and a buffer layer. The buffer layer may be supported by a flexible material, and one side of the buffer layer is connected to the deformable layer and the other side is for direct contact with the second surface S2 of the silicon wafer S to absorb the impact of the deformable layer on the silicon wafer.

[0058] In other embodiments of this disclosure, the gasket assembly 21 may be made of a thermally expanding material that expands and deforms when heated, such as polyurethane, silicone rubber, etc. The gasket assembly 21 can undergo localized deformation under localized heating. Furthermore, when the gasket assembly 21 is made of polyurethane, silicone rubber, etc., the gasket assembly 21 can directly contact the second surface S2 of the silicon wafer S without causing damage.

[0059] The polishing method described above is further described below with reference to Figures 3 to 5.

[0060] In the state shown in Figure 4, the silicon wafer S to be polished has been mounted to the polishing head 200, the temperature control module 22 has not yet started operating, and the pad assembly 21 is in its initial shape. The pad assembly 21 can be configured in the polishing head to partially contact the second surface S2 of the silicon wafer S, or not contact at all, but merely be adjacent. In the embodiment shown in the figure, the initial shape of the pad assembly 21 is configured to have a flat surface. In other embodiments not shown, the pad assembly 21 can be configured to have other initial shapes depending on the morphology of the silicon wafer S before polishing, so as to more efficiently transform into at least partially conforming to the second surface S2 of the silicon wafer S.

[0061] As clearly shown in the figure, the initial morphology of the silicon wafer S to be polished is poor, exhibiting a certain degree of warping. Therefore, the first surface S1 has an uneven shape, i.e., it simultaneously has protruding and recessed portions. In the various embodiments of this disclosure, the protruding portion refers to the portion on the first or second surface of the silicon wafer that protrudes outward relative to the geometric center plane of the silicon wafer, and the recessed portion refers to the portion on the first or second surface of the silicon wafer that is recessed inward relative to the geometric center plane.

[0062] If the goal is to improve the flatness of the first surface S1 through polishing, the amount of material removed from the raised portions of the first surface S1 should be greater than the amount of material removed from the recessed portions. However, when the pad assembly 21 has a flat surface, it cannot provide ideal support for the silicon wafer S. As shown in Figure 4, since the raised portions on the first surface S1 of the silicon wafer S correspond to the recessed portions on the second surface S2 in the thickness direction of the wafer, and the flat pad assembly 21 cannot fit the recessed portions on the second surface S2, the raised portions on the first surface S1 cannot receive sufficient support during polishing. This prevents the pressure applied by the polishing head from being directly transmitted from the entire second surface S2 along the thickness direction of the wafer to the first surface S1, thus failing to achieve effective material removal from the raised portions on the first surface S1.

[0063] To address the aforementioned issues, the temperature control module 22 can adjust the temperature of the pad assembly 21 based on the target morphology of the silicon wafer S to be polished and the initial morphology of the first surface S1. Figure 5 shows the pad assembly 21 after local expansion and deformation due to temperature changes. After this local deformation, the pad assembly 21 can contact a portion of the second surface S2 corresponding to the protrusion of the first surface S1 along the thickness direction of the silicon wafer. This allows the pressure of the polishing head to be accurately transmitted to the silicon wafer S via the contact portion between the pad assembly 21 and the second surface S2, facilitating effective material removal from the silicon wafer S, particularly from the portion of the first surface S1 corresponding to the contact portion in the thickness direction, while the remaining portion of the first surface S1 of the silicon wafer S can be removed with relatively little or no material.

[0064] After the pad assembly 21 is deformed to achieve the desired fit with the second surface S2 of the silicon wafer S, a polishing operation can be performed. The protruding portions on the first surface S1, receiving sufficient polishing pressure transmitted via the pad assembly 21, can be polished before the recessed portions. This means that after one polishing operation, the amount of polishing on the protruding portions of the first surface S1 will be greater than the amount of polishing on the recessed portions; that is, the amount of material removed from the protruding portions of the first surface S1 will be greater than the amount of material removed from the recessed portions. Consequently, the polished silicon wafer will have better flatness. In summary, for the entire silicon wafer, the silicon wafer S polished using the polishing head 200 achieves the desired level of flatness due to the material removal distribution scheme customized according to the initial morphology of its first surface S1.

[0065] Some embodiments of this disclosure provide a polishing method and polishing apparatus. The polishing method includes: while a silicon wafer is held by a polishing head, precisely controlling the shape of a pad assembly of the polishing head through temperature regulation to cause the pad assembly to adhere to the silicon wafer at a predetermined position, thereby achieving customized control of the pressure distribution in different areas of the silicon wafer during the polishing process. This customized pressure distribution further enables customized distribution of material removal. Since the predetermined position where the pad assembly adheres to the silicon wafer can be determined based on the target morphology of the silicon wafer and its initial morphology before polishing, this polishing method can precisely control the material removal distribution of each silicon wafer during the polishing process through precise pressure regulation to meet the specific needs of each silicon wafer, ultimately obtaining a silicon wafer with a desired morphology.

[0066] In some embodiments of this disclosure, referring to Figures 4 and 5, the pad assembly 21 includes a plurality of deformable regions capable of deforming independently of each other, and the temperature control module 22 includes a plurality of temperature control units configured to independently adjust the temperature of each of the plurality of deformable regions of the pad assembly 21. Accordingly, adjusting the temperature of the pad assembly 21 includes independently adjusting the temperature of each of the deformable regions of the pad assembly 21.

[0067] Specifically, in order to achieve localized temperature regulation of the gasket assembly 21, the temperature regulation module 22 can be divided into multiple independent temperature regulation sections. These temperature regulation sections can independently control the temperature of their respective areas, thereby achieving temperature regulation of different areas of the gasket assembly. In the embodiment shown in FIG5, three of the multiple temperature regulation sections of the temperature regulation module 22, namely the first temperature regulation section 22A, the second temperature regulation section 22B, and the third temperature regulation section 22C, respectively regulate the temperature of three parts of the gasket assembly 21 adjacent to them.

[0068] Since the heat transfer path along the thickness direction of the pad assembly 21 is the shortest, the portion of the pad assembly 21 that is approximately aligned with the three temperature-regulating sections along the thickness direction of the pad assembly 21 can deform to the maximum extent in response to temperature regulation. In contrast, other areas of the pad assembly 21 deform less or not at all. Therefore, the entire pad assembly 21, after local deformation, presents the state shown in Figure 5. The deformed pad assembly 21 enables adhesion to at least a portion of the second surface S2 of the silicon wafer S.

[0069] The distribution of the temperature-regulating sections in the temperature-regulating module 22 can be determined based on the initial morphology of the silicon wafer S before polishing. In the field of silicon wafer manufacturing, common types of silicon wafer warpage include: bow-shaped warpage, where the center of the silicon wafer is relatively high and arched; and butterfly-shaped warpage, where the center of the wafer is relatively low and butterfly-shaped. In some embodiments of this disclosure, for both types of warpage, at least a portion of the plurality of temperature-regulating sections are disposed at different positions in the radial direction of the held silicon wafer S.

[0070] As shown in Figure 6, the surface of the temperature control module 22 adjacent to the gasket assembly 21 can be approximately circular. The temperature control section of the temperature control module 22 can be divided into two groups. The first group of temperature control sections includes four first temperature control sections 22A, and the second group of temperature control sections includes four second temperature control sections 22B. The second group of temperature control sections is farther from the center of the temperature control module 22 than the first group of temperature control sections.

[0071] By arranging multiple temperature-regulating sections in the above-described distribution, when polishing silicon wafers with bow-shaped or butterfly-shaped warping, the first temperature-regulating section 22A or the second temperature-regulating section 22B can be selectively activated, causing the pad assembly 21 to deform in its central or edge region, thereby correspondingly adhering to the central or edge region of the second surface S2 of the silicon wafer S, thereby increasing the polishing amount, i.e., the material removal amount, of the first surface S1 of the silicon wafer S in the central or edge region.

[0072] In some embodiments of this disclosure, referring to FIG7, the plurality of temperature-regulating sections are arranged in a plurality of annular shapes concentrically with the silicon wafer S being held.

[0073] As shown in Figure 7, the temperature control module 22 can be divided into multiple independent temperature control sections. These areas are arranged in concentric rings, corresponding to various radial positions of the silicon wafer S from the center to the edge. The independent temperature control capability of each ring area allows for individual adjustment of the temperature of the corresponding ring area of ​​the pad assembly 21, causing these ring areas of the pad assembly 21 to deform and conform to the corresponding ring area of ​​the second surface S2 of the silicon wafer S, thereby transmitting pressure more evenly to the silicon wafer S. For silicon wafers exhibiting common types of warpage, such as bow-shaped warpage and butterfly-shaped warpage, this allows for a more suitable distribution of material removal amount to its initial morphology.

[0074] According to some embodiments of this disclosure, referring to FIG5, the temperature control module 22 may include a controller 221 and a heater 222. The controller 221 may be configured to control the heater 222 to heat the pad assembly 21 at one or more target temperature control sections among a plurality of temperature control sections. Accordingly, temperature regulation of the pad assembly 21 includes independently heating one or more target deformable regions of a plurality of deformable regions of the pad assembly 21.

[0075] The controller 221 can be used to selectively activate one or more of a plurality of temperature control units. The selected temperature control unit may also be referred to as the target temperature control unit. A plurality of heaters 222 may be arranged corresponding to the plurality of temperature control units respectively. Each heater can be responsible for independently adjusting the temperature of its respective temperature control unit, thereby achieving precise control of the amount of material removed from different areas of the first surface S1 of the silicon wafer S.

[0076] Furthermore, in some embodiments of this disclosure, the controller 221 may also be configured to determine one or more target temperature-regulating sections from the plurality of temperature-regulating sections based on the morphology of the first surface S1 of the held silicon wafer S. Accordingly, temperature regulation of the pad assembly includes determining one or more target deformable regions from the plurality of deformable regions of the pad assembly 21 based on the morphology of the first surface S1 of the held silicon wafer S.

[0077] To improve the versatility of the polishing head 200, the temperature control module 22 can be configured to have multiple temperature control sections. When the polishing head 200 is used, one or more suitable temperature control sections can be selected as target temperature control sections based on the specific morphology of the silicon wafer S to be polished. The selected target temperature control section is then activated to perform temperature control operations on the pad assembly 21, while unselected temperature control sections can remain inactive during the polishing process. As mentioned above, according to the technical concept of this disclosure, the material removal amount distribution scheme for the silicon wafer can be determined based on the target morphology of the silicon wafer and its initial morphology before polishing. When using the polishing method and polishing equipment provided in the embodiments of this disclosure, the incoming silicon wafer, i.e., before polishing, can first undergo morphology detection. Then, the morphology detection result is compared with the target morphology parameters of the silicon wafer. Based on this comparison result, a specific material removal amount distribution scheme can be formulated. Correspondingly, the pressure distribution scheme for the silicon wafer during the upcoming polishing process can be obtained.

[0078] According to embodiments of this disclosure, by cooperating with the controller 221 and heater 222 in the temperature control module 22, and by rationally selecting the target temperature control section based on specific morphological data, independent heating control of multiple temperature control sections can be achieved, thereby precisely adjusting the pressure applied by the pad assembly 21 to different areas of the silicon wafer S. This control method not only improves polishing accuracy and uniformity but also enhances the flexibility and adaptability of the polishing head 200, thereby increasing production efficiency and yield.

[0079] In some embodiments of this disclosure, referring to FIG8, the pad assembly 21 may include a pad body 211 and an adsorption pad 212 attached to the pad body 211 for adsorbing the silicon wafer S, wherein the temperature control module 22 is configured to adjust the temperature of the pad body 211 to deform the pad body 211, and the adsorption pad 212 is configured to deform as the pad body 211 deforms to at least partially conform to the second surface S2 of the held silicon wafer S.

[0080] As shown in Figure 8, the pad body 211 can be positioned adjacent to or in direct contact with the temperature control module 22. The adsorption pad 212 can be positioned on the side of the pad body 211 opposite to the temperature control module 22 and attached to the pad body 211. The surface of the adsorption pad 212 adjacent to the second surface S2 of the silicon wafer S can be configured to have a shape and size corresponding to the second surface S2 of the silicon wafer S.

[0081] In some embodiments of this disclosure, the pad body 211 may be made of a material that undergoes significant shape changes but little volume change when heated, such as shape memory alloys or shape memory polymers.

[0082] In other embodiments of this disclosure, the pad body 211 may be made of a thermally expanding material that expands and deforms when heated, such as polyurethane, silicone rubber, etc. The pad body 211 may undergo localized deformation under localized heating.

[0083] In some embodiments of this disclosure, the adsorption pad 212 may be made of a flexible material so that it deforms along with the pad body 211 to which it is attached. The adsorption pad 212 can securely fix the silicon wafer S to the polishing head 200 by means of, for example, vacuum adsorption or electrostatic adsorption, ensuring that the silicon wafer S does not slip or detach from the polishing head 200 during the polishing process.

[0084] Since the adsorption pad 26 can deform with the deformation of the pad body 211, the pad assembly 21 containing the adsorption pad 26 can still achieve the desired material removal distribution.

[0085] As an example, the absorbent pad can be made of materials such as foamed polyurethane or a composite of polyester and polyurethane.

[0086] In some embodiments of this disclosure, silicon wafers with a total thickness variation (TTV) of less than 100 nanometers and a site flatness (SFQR) of less than 20 nanometers can be obtained by using the polishing equipment provided in the embodiments of this disclosure. Table 1 lists the total thickness variation and site flatness of silicon wafers #1 to #5 after polishing using the polishing method provided in the embodiments of this disclosure.

[0087] Table 1

[0088] It should be noted that the technical solutions described in the embodiments of this disclosure can be combined arbitrarily without conflict.

[0089] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A polishing method, the polishing method comprising: A silicon wafer is held by a polishing head, wherein, while the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head; The pad assembly is temperature-regulated to deform it into at least partially conforming to the second surface of the held silicon wafer, so that during polishing, the pressure on the pad assembly is transmitted to the silicon wafer via the portion conforming to the second surface of the silicon wafer.

2. The polishing method according to claim 1, wherein, The padding assembly includes a plurality of deformable regions capable of deforming independently of each other, and the temperature regulation of the padding assembly includes: independently regulating the temperature of each of the plurality of deformable regions of the padding assembly.

3. The polishing method according to claim 2, wherein, The temperature regulation of the pad assembly includes: independently heating one or more target deformable regions of the plurality of deformable regions of the pad assembly.

4. The polishing method according to claim 3, wherein, The temperature conditioning of the pad assembly includes: determining one or more target deformation regions from the plurality of deformable regions of the pad assembly based on the morphology of the first surface of the held silicon wafer.

5. The polishing method according to any one of claims 1 to 4, wherein, The pad assembly includes a pad body and an adsorption pad for adsorbing silicon wafers, which is attached to the pad body. Accordingly, the temperature conditioning of the pad assembly to deform the pad assembly into at least partially conforming to the second surface of the held silicon wafer includes: temperature conditioning the pad body to deform the pad body and the adsorption pad deforms with the deformation of the pad body into at least partially conforming to the second surface of the held silicon wafer.

6. A polishing apparatus for performing the polishing method according to any one of claims 1 to 5, the polishing apparatus comprising: A polishing head for holding a silicon wafer, wherein, when the silicon wafer is held by the polishing head, a first surface of the silicon wafer is exposed and a second surface of the silicon wafer opposite to the first surface is adjacent to a pad assembly of the polishing head; A temperature control module is provided for temperature regulation of the pad assembly to deform the pad assembly into at least partially contacting the second surface of the held silicon wafer, so that during polishing, the pressure on the pad assembly is transmitted to the silicon wafer via the portion of the pad assembly that is in contact with the second surface of the silicon wafer.

7. The polishing equipment according to claim 6, wherein, The gasket assembly includes a plurality of deformable regions that are capable of deforming independently of each other, and the temperature control module includes a plurality of temperature control units configured to independently adjust the temperature of the plurality of deformable regions of the gasket assembly.

8. The polishing equipment according to claim 7, wherein, At least a portion of the multiple temperature-regulating sections are disposed at different positions in the radial direction of the silicon wafer being held.

9. The polishing equipment according to claim 8, wherein, The plurality of temperature-regulating sections are arranged in a plurality of annular shapes concentrically with the silicon wafer being held.

10. The polishing apparatus according to any one of claims 6 to 9, wherein, The pad assembly includes a pad body and an adsorption pad for adsorbing silicon wafers, which is attached to the pad body. The temperature control module is configured to adjust the temperature of the pad body to deform the pad body, and the adsorption pad is configured to deform with the deformation of the pad body to at least partially conform to the second surface of the held silicon wafer.

11. A silicon wafer obtained by using a polishing method according to any one of claims 1 to 5, wherein, The total thickness deviation of the silicon wafer is less than 100 nanometers, and the local flatness is less than 20 nanometers.

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