Polishing method, polishing equipment and silicon wafer

Abstract

The embodiment of the invention provides a polishing method, polishing equipment and a silicon wafer, the polishing method comprises the following steps: a polishing head is used for holding the silicon wafer, and under the condition that the silicon wafer is held by the polishing head, the polishing head is used for polishing the silicon wafer; the first surface of the silicon wafer is exposed, and the second surface, opposite to the first surface, of the silicon wafer is adjacent to a gasket assembly of the polishing head; and the temperature of the liner assembly is adjusted, so that the liner assembly is deformed to be at least partially attached to the second surface of the kept silicon wafer, and therefore in the polishing process, pressure borne by the liner assembly is transmitted to the silicon wafer through the portion, attached to the second surface of the silicon wafer, of the liner assembly.

Description

Technical Field

[0001] The embodiments of the present disclosure relate to the technical field of silicon wafer processing, and in particular to a polishing method, a polishing device and a silicon wafer. Background Art

[0002] In the field of semiconductor manufacturing, with the development of technology, the requirements for the surface flatness of silicon wafers are becoming increasingly stringent. In order to improve the surface flatness of silicon wafers, the manufacturing process usually 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.

[0003] During the final polishing process, the silicon wafer is attracted to the polishing head and pressed against the polishing pad located below the polishing head. The front side of the silicon wafer is finely polished by the polishing pad. The amount of material removed during this process has a decisive influence on the flatness of the silicon wafer after polishing, especially the overall flatness and edge flatness. In addition, the morphology of the silicon wafer before the final polishing will also affect the flatness after the final polishing.

[0004] At present, in the continuous processing flow, the impact of the morphological differences of different silicon wafers before entering the final polishing on the final polishing effect has not been fully considered, but the same process parameters are used to process different silicon wafers. This non-differentiated processing often results in the polished silicon wafers not meeting the precise size and shape requirements.

[0005] Therefore, tailoring the polishing process parameters according to the expected size and shape after polishing and the specific morphology of each silicon wafer before final polishing is of significant importance in improving the overall quality of silicon wafer manufacturing. Summary of the invention

[0006] In view of this, the embodiments of the present disclosure are intended to provide a polishing method, a polishing device, and a silicon wafer. By using the polishing method, the distribution of the pressure applied to the silicon wafer can be accurately controlled by the deformation of the pad assembly with temperature, so as to customize the material removal amount according to the expected size and shape of the silicon wafer and the specific morphology of the silicon wafer before polishing, thereby achieving the expected polishing effect.

[0007] The technical solution of the embodiment of the present disclosure is implemented as follows: In a first aspect, an embodiment of the present disclosure provides a polishing method, the polishing method comprising: holding a silicon wafer with a polishing head, wherein, with the silicon wafer 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 the pad assembly to at least partially fit the second surface of the held silicon wafer, so that during polishing, the pressure exerted on the pad assembly is transmitted to the silicon wafer via the portion fitting the second surface of the silicon wafer.

[0008] In some optional examples, the cushion component includes a plurality of deformable regions that can deform independently of each other, and the temperature regulating the cushion component includes: independently temperature regulating each of the plurality of deformable regions of the cushion component.

[0009] In some optional examples, the temperature regulating the cushion component includes: independently heating one or more target deformation regions among the plurality of deformable regions of the cushion component.

[0010] In some optional examples, the temperature regulating the pad assembly includes: determining the one or more target deformation regions from the plurality of deformable regions of the pad assembly according to the morphology of the first surface of the held silicon wafer.

[0011] In some optional examples, the pad assembly includes a pad body and an adsorption pad coupled to the pad body for adsorbing a silicon wafer. Correspondingly, the temperature adjustment of the pad assembly so that the pad assembly is deformed to at least partially fit the second surface of the held silicon wafer includes: temperature adjustment of the pad body so that the pad body is deformed and the adsorption pad is deformed to at least partially fit the second surface of the held silicon wafer as the pad body is deformed.

[0012] In a second aspect, an embodiment of the present disclosure provides a polishing device, the polishing device is used to perform the polishing method according to the first aspect, the polishing device comprising: a polishing head for holding a silicon wafer, wherein, with the silicon wafer 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 used to adjust the temperature of the pad assembly so that the pad assembly is deformed to at least partially fit the second surface of the held silicon wafer, so that during the polishing process, the pressure exerted on the pad assembly is transmitted to the silicon wafer via the portion where the pad assembly fits the second surface of the silicon wafer.

[0013] In some optional examples, the cushion assembly includes a plurality of deformable regions that can deform independently of each other, and the temperature adjustment module includes a plurality of temperature adjustment parts configured to independently adjust the temperature of the plurality of deformable regions of the cushion assembly.

[0014] In some optional examples, at least a portion of the plurality of temperature adjustment portions are disposed at different positions in a radial direction of the held silicon wafer.

[0015] In some optional examples, the plurality of temperature adjustment portions are configured to be in a plurality of annular shapes arranged concentrically with the held silicon wafer.

[0016] In some optional examples, the pad assembly includes a pad body and an adsorption pad coupled to the pad body for adsorbing a silicon wafer. 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 be deformed into at least partially fitting the second surface of the held silicon wafer as the pad body deforms.

[0017] In a third aspect, an embodiment of the present disclosure provides a silicon wafer obtained by using the 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.

[0018] Some embodiments of the present disclosure provide a polishing method. The polishing method includes: when a silicon wafer is held by a polishing head, the shape of a pad assembly of the polishing head is precisely controlled by temperature regulation so that the pad assembly fits the silicon wafer at a predetermined position, thereby achieving customized control of the pressure distribution of different areas of the silicon wafer during the polishing process. This customized pressure distribution further achieves a customized distribution of material removal. Since the predetermined position where the pad assembly fits the silicon wafer can be determined based on the target morphology of the silicon wafer and the initial morphology before polishing, the 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, and finally obtain a silicon wafer with a desired morphology. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A schematic diagram of a polishing device provided in an embodiment of the present disclosure; Figure 2 A flow chart of a polishing method provided in an embodiment of the present disclosure; Figure 3 A schematic diagram of a polishing device provided for another embodiment of the present disclosure; Figure 4 A schematic diagram of a polishing head provided for an embodiment of the present disclosure; Figure 5 for Figure 4 Another schematic diagram of the polishing head shown; Figure 6 A schematic diagram of a portion of a polishing head provided for an embodiment of the present disclosure; Figure 7 A schematic diagram of a portion of a polishing head provided for another embodiment of the present disclosure; Figure 8 A schematic diagram of a polishing head provided for another embodiment of the present disclosure. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure.

[0021] Microscopic damage and stress concentration may be introduced on the surface of silicon wafers during the early processing of silicon wafer manufacturing, such as cutting and grinding. The microscopic defects on the surface of silicon wafers can be removed through the final polishing process to improve the surface flatness of silicon wafers.

[0022] Figure 1 , a polishing device 10 provided by some embodiments of the present disclosure is shown. The polishing device 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 along with the polishing table 11 through the drive of the drive shaft 13. For example, when the polishing table 11 rotates in a clockwise direction under the drive of the drive shaft 13, the polishing pad 12 also rotates in a counterclockwise direction.

[0023] In addition, a polishing head 14 is arranged in the upper space of the polishing table 11, and the polishing head 14 may at least include: a head body 141, a rotating driving member 142 connected to the head body 141, and an assembly mold 143 arranged below the head body 141. A rubber pad 144 is arranged in the first accommodating cavity CS1 formed by the assembly mold 143. The silicon wafer S to be polished is also accommodated in the first accommodating cavity CS1. The rubber pad 144 can be connected to the head body 141. The vacuum / air pipe 145 is used to supply compressed dry air to the first accommodating cavity CS1 of the assembly mold 143 to form a working pressure. The working pressure can act on the rubber pad 144 and be transmitted to the silicon wafer S to be polished via the rubber pad 144.

[0024] The head body 141 can be driven by the rotary drive member 142 to rotate, so that the head body 141 and the silicon wafer S accommodated in the first accommodation cavity CS1 of the assembly mold 143 can also rotate with the rotation of the head body 141. For example, when the rotary drive member 142 rotates in the counterclockwise direction, the head body 141 and the silicon wafer S to be polished also rotate in the counterclockwise direction.

[0025] The polishing device 10 may further 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 of the polishing liquid may be controlled by a valve.

[0026] When performing the polishing operation, the rotating polishing head 14 presses the silicon wafer onto the rotating polishing pad 12 at a certain working pressure, and the polishing liquid composed of submicron or nano abrasive particles and chemical solution drips onto the polishing pad 12 through the nozzle 15. Then, the polishing liquid can be evenly distributed on the polishing pad 12 under the transmission of the polishing pad 12 and the action of centrifugal force. During the distribution process, the polishing liquid can flow between the surface of the silicon wafer S and the polishing pad 12 to form a thin film of polishing liquid between the two. The chemical components in the polishing liquid can react chemically with the surface material of the silicon wafer, converting insoluble substances into soluble substances, or softening substances with high hardness. Then, these chemical reactants are removed from the surface of the silicon wafer through the micromechanical friction of the abrasive particles, dissolved into the flowing liquid and taken away, that is, the purpose of flattening is achieved in the alternating process of chemical film formation and mechanical film removal.

[0027] The inventors note that for the above-mentioned polishing device 10, since the pressure of the grinding head is transmitted to the silicon wafer S to be polished as a whole in the vertical direction via a single rubber pad 144, the amount of material removed from each area on the entire polishing surface of the silicon wafer S is basically the same. However, in actual production, due to various factors existing in the previous processing, the morphology and flatness of different silicon wafers before the final polishing are different. In this case, if a uniform material removal scheme is still adopted for each silicon wafer during polishing, the polished silicon wafer is likely to fail to meet the target morphology requirements.

[0028] Based on this, the inventors believe after research that: in order to make the polished silicon wafer meet the target morphology requirements, it is necessary to set a material removal amount distribution scheme specifically according to the target morphology of each silicon wafer and the initial morphology before polishing. In other words, for a single silicon wafer, a consistent material removal amount should no longer be set for each area on its polished surface, but the corresponding material removal amount should be set according to the specific conditions of different areas; for different silicon wafers, a unified material removal amount distribution scheme is no longer used, but a corresponding material distribution scheme should be adopted according to the target morphology and initial morphology of each silicon wafer.

[0029] Through further research, the inventors also found that the material removal during the polishing process mainly depends on the friction between the polishing pad and the surface of the silicon wafer caused by the abrasive particles in the polishing liquid. When the pressure applied to the silicon wafer increases, the contact area and contact strength between the abrasive particles and the surface of the silicon wafer will increase, so that the abrasive particles are embedded in the surface of the silicon wafer to a greater extent and more deeply, 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 removal on different areas of the silicon wafer can be different, so as to obtain a silicon wafer that meets the target morphology requirements.

[0030] In view of the above, the embodiments of the present disclosure provide a polishing method, a polishing device, and a silicon wafer. By using the polishing method, the distribution of the pressure applied to the silicon wafer can be accurately controlled by the deformation of the pad assembly with temperature, so as to customize the material removal amount according to the expected size and shape of the silicon wafer and the specific morphology of the silicon wafer before polishing, thereby achieving the expected polishing effect.

[0031] The embodiments of the present disclosure are described in detail below with reference to the accompanying drawings.

[0032] See also Figure 2 , some embodiments of the present disclosure provide a polishing method, the polishing method comprising: S101: holding a silicon wafer 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; S102: regulating the temperature of the pad assembly to deform the pad assembly to at least partially fit the second surface of the held silicon wafer, so that during the polishing process, the pressure exerted on the pad assembly is transmitted to the silicon wafer via the portion fitting the second surface of the silicon wafer.

[0033] See also Figure 3 Some embodiments of the present disclosure also provide a polishing device 100. The polishing device 100 may include a polishing head 200. Figure 4 The following is a description of the polishing device 100 and the polishing head 200. Figure 1 The polishing method is described in detail.

[0034] The polishing head 200 is used to hold the silicon wafer S so that the first surface S1 of the silicon wafer S is exposed, and the polishing head 200 may include a pad assembly 21 and a temperature adjustment module 22. The pad assembly 21 may be arranged in the polishing head 200 so that, when the silicon wafer is held by the polishing head 200, the pad assembly 21 is adjacent to the second surface S2 of the held silicon wafer S, wherein the first surface S1 is opposite to the second surface S2. The temperature adjustment module 22 may be arranged to adjust the temperature of the pad assembly 21 so that the pad assembly 21 is deformed to at least partially fit the second surface S2 of the held silicon wafer S, so that during the polishing process, the pressure on the pad assembly 21 may be transmitted to the silicon wafer S via the portion where the pad assembly 21 fits the second surface S2 of the silicon wafer S.

[0035] like Figure 2 As shown, the polishing head 200 may include a body 23 and a holding portion 24 extending from one surface of the body 23. When the polishing head 200 is in use, the holding portion 24 is located on the lower surface of the body 23 and may be substantially annular to form a downwardly open chamber 25 with the body 23 so as to accommodate the silicon wafer S therein.

[0036] In various embodiments of the present 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 accommodated in the chamber 25, the first surface S1 to be polished is exposed to the surrounding environment, while the second surface S2 faces the direction of the body 23.

[0037] The surface of the pad component 21 adjacent to the second surface S2 of the silicon wafer S may have a shape and size corresponding to the second surface S2. The pad component 21 may also be disposed in the chamber 25, and the temperature adjustment module 22 may be disposed between the body 23 and the pad component 21. The temperature adjustment module 22 may be disposed adjacent to the pad component 21 or in direct contact with the pad component 21 to transfer its own temperature to the pad component 21 through air or directly.

[0038] The temperature adjustment module 22 may be configured to at least partially adjust the temperature of the cushion component 21. In some embodiments of the present disclosure, the temperature adjustment module 22 is configured to be able to adjust the temperature of any area on the surface of the cushion component 21 adjacent to the temperature adjustment module 22.

[0039] The pad component 21 can be made of a material that can be deformed after being heated. In some embodiments of the present disclosure, the pad component 21 can be made of a material that undergoes a significant shape change but a small volume change when heated, for example, it can be made of a shape memory alloy or a shape memory polymer. In this case, in order to avoid the pad component 21 from causing damage to the second surface S2 of the silicon wafer S. The pad component 21 may include a pad body and a buffer layer that can be deformed. The buffer layer may be supported by a flexible material, and one side of the buffer layer is connected to the deformation layer and the other side is used to directly contact the second surface S2 of the silicon wafer S to absorb the impact of the deformation layer on the silicon wafer.

[0040] In other embodiments of the present disclosure, the pad component 21 may be made of a thermal expansion material that expands and deforms when heated, such as polyurethane, silicone rubber, etc. When the pad component 21 is locally heated, it may be locally deformed. In addition, when the pad component 21 is made of polyurethane, silicone rubber, etc., the pad component 21 may be in direct contact with the second surface S2 of the silicon wafer S without causing damage thereto.

[0041] Combine the following Figures 3 to 5 The above-mentioned polishing method is further described.

[0042] exist Figure 4 In the state shown, the silicon wafer S to be polished has been installed on the polishing head 200, the temperature control module 22 has not yet started working, and the pad assembly 21 is in the initial shape. The pad assembly 21 can be arranged in the polishing head to partially contact the second surface S2 of the silicon wafer S, or not contact at all, just adjacent. In the embodiment shown in the figure, the initial shape of the pad assembly 21 is arranged to have a flat surface. In other embodiments not shown, the pad assembly 21 can be arranged to have other initial shapes according to the morphology of the silicon wafer S before polishing, so as to more efficiently deform into at least partially fit the second surface S2 of the silicon wafer S.

[0043] As clearly shown in the figure, the initial morphology of the silicon wafer S to be polished is not good and there is a certain degree of warping, so the first surface S1 is uneven, that is, it has both convex parts and concave parts. In each embodiment of the present disclosure, the convex part refers to the part on the first surface or the second surface of the silicon wafer that protrudes outward relative to the geometric center plane of the silicon wafer, and the concave part refers to the part on the first surface or the second surface of the silicon wafer that is concave inward relative to the geometric center plane.

[0044] If it is desired to improve the flatness of the first surface S1 through the polishing operation, the amount of material removed from the convex portion of the first surface S1 should be greater than the amount of material removed from the concave portion of the first surface S1. However, in the case where the pad component 21 has a flat surface, it cannot provide ideal support for the silicon wafer S. Figure 4 As shown, since the convex portion on the first surface S1 of the silicon wafer S corresponds to the concave portion on the second surface S2 in the thickness direction of the silicon wafer, and the flat pad assembly 21 cannot fit the concave portion on the second surface S2, the convex portion on the first surface S1 cannot be adequately supported during the polishing process. This will make it impossible for the pressure applied by the polishing head to be directly transmitted from the entire second surface S2 to the first surface S1 along the thickness direction of the silicon wafer, and thus it is impossible to effectively remove the material of the convex portion on the first surface S1.

[0045] In order to solve the above problem, the temperature adjustment module 22 can adjust the temperature of the pad assembly 21 according to the target morphology of the silicon wafer S to be polished and the initial morphology of the first surface S1. Figure 5 2 shows the pad assembly 21 after local expansion and deformation due to temperature change. The pad assembly 21 after local deformation can contact the portion of the second surface S2 corresponding to the raised portion of the first surface S1 along the thickness direction of the silicon wafer. This enables 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, so as to help achieve effective material removal for the silicon wafer S, especially the portion of the first surface S1 of the silicon wafer S corresponding to the above-mentioned contact portion in the thickness direction, while the rest of the first surface S1 of the silicon wafer S can be relatively less or no material is removed.

[0046] After the pad assembly 21 is deformed to achieve the expected bonding effect with the second surface S2 of the silicon wafer S, a polishing operation can be performed. The raised portion on the first surface S1 can be polished before the recessed portion because it receives sufficient polishing pressure transmitted through the pad assembly 21. This means that after the first surface S1 has undergone a polishing operation, the polishing amount of the raised portion on the first surface S1 will be greater than the polishing amount of the recessed portion, that is, the material removal amount of the raised portion on the first surface S1 will be greater than the material removal amount of the recessed portion, and the polished silicon wafer obtained will have better flatness. In summary, for the entire silicon wafer, the silicon wafer S after being polished using the polishing head 200 can achieve the desired flatness level because it has undergone a material removal distribution scheme customized according to the initial morphology of its first surface S1.

[0047] Some embodiments of the present disclosure provide a polishing method and a polishing device. The polishing method includes: when the silicon wafer is held by the polishing head, the shape of the pad assembly of the polishing head is precisely controlled by temperature regulation so that the pad assembly fits the silicon wafer at a predetermined position, thereby achieving customized control of the pressure distribution of different areas of the silicon wafer during the polishing process. This customized pressure distribution further achieves a customized distribution of material removal. Since the predetermined position where the pad assembly fits the silicon wafer can be determined based on the target morphology of the silicon wafer and the initial morphology before polishing, the polishing method can be used to 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, and finally obtain a silicon wafer with a desired morphology.

[0048] In some embodiments of the present disclosure, see Figure 4 and Figure 5 The pad component 21 includes a plurality of deformable regions that can deform independently of each other, and the temperature adjustment module 22 includes a plurality of temperature adjustment parts configured to independently adjust the temperature of the plurality of deformable regions of the pad component 21. Accordingly, adjusting the temperature of the pad component 21 includes: independently adjusting the temperature of the deformable regions of the pad component 21.

[0049] Specifically, in order to achieve local temperature adjustment of the pad assembly 21, the temperature adjustment module 22 can be divided into a plurality of independent temperature adjustment parts. These temperature adjustment parts can independently control the temperature of their respective areas, thereby achieving temperature adjustment of different areas of the pad assembly. Figure 5 In the embodiment shown in FIG. 1 , three of the multiple temperature adjustment parts of the temperature adjustment module 22 , namely the first temperature adjustment part 22A, the second temperature adjustment part 22B and the third temperature adjustment part 22C, respectively adjust the temperature of three parts of the pad assembly 21 adjacent thereto.

[0050] Since the heat transfer path along the thickness direction of the cushion component 21 is the shortest, the cushion component portion roughly aligned with the three temperature adjustment portions along the thickness direction of the cushion component 21 can deform to the greatest extent in response to the temperature adjustment effect. In comparison, the deformation degree of other areas of the cushion component 21 is small, or no deformation occurs. Therefore, for the entire cushion component 21, the partial deformation presents Figure 5 The deformed pad component 21 can be bonded to at least a portion of the second surface S2 of the silicon wafer S.

[0051] The distribution of the temperature adjustment parts of the temperature adjustment module 22 can be determined according to the initial morphology of the silicon wafer S before polishing. In the field of silicon wafer manufacturing, common types of silicon wafer warping include: bow warping, that is, the center of the silicon wafer is relatively high and bow-shaped; butterfly warping, that is, the center of the wafer is relatively low and butterfly-shaped. In some embodiments of the present disclosure, for the above two types of warping, at least a part of the multiple temperature adjustment parts are arranged at different positions in the radial direction of the held silicon wafer S.

[0052] like Figure 6 As shown, the surface of the temperature regulating module 22 adjacent to the pad assembly 21 can be roughly circular. The temperature regulating parts of the temperature regulating module 22 can be divided into two groups, the first group of temperature regulating parts includes four first temperature regulating parts 22A, and the second group of temperature regulating parts includes four second temperature regulating parts 22B, wherein the second group of temperature regulating parts is farther from the center of the temperature regulating module 22 than the first group of temperature regulating parts.

[0053] By arranging a plurality of temperature adjustment sections in the above-mentioned distribution manner, when polishing a silicon wafer with bow-shaped warping or butterfly-shaped warping, the first temperature adjustment section 22A or the second temperature adjustment section 22B can be selectively enabled, so that the pad assembly 21 can be deformed in its central area or edge area, thereby correspondingly fitting the central area or edge area of ​​the second surface S2 of the silicon wafer S, so as to increase the polishing amount of the first surface S1 of the silicon wafer S in the central area or edge area, that is, the material removal amount.

[0054] In some embodiments of the present disclosure, see Figure 7 The plurality of temperature adjustment parts are arranged in a plurality of annular shapes concentrically with the held silicon wafer S.

[0055] like Figure 7 As shown, the temperature adjustment module 22 can be divided into a plurality of independent temperature adjustment parts, which are arranged in concentric annular shapes corresponding to various radial positions from the center to the edge of the silicon wafer S. The independent temperature adjustment capability of each annular area enables the temperature of the corresponding annular area of ​​the pad assembly 21 to be adjusted separately, so that these annular areas of the pad assembly 21 are deformed to fit the corresponding annular areas of the second surface S2 of the silicon wafer S, thereby transmitting the pressure to the silicon wafer S more evenly. For silicon wafers with common types of warpage, such as bow warpage and butterfly warpage, this can make the distribution of material removal more suitable for their initial morphology.

[0056] According to some embodiments of the present disclosure, see Figure 5The temperature adjustment 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 cushion component 21 at one or more target temperature adjustment parts among the plurality of temperature adjustment parts. Accordingly, temperature adjustment of the cushion component 21 includes: independently heating one or more target deformation areas of the plurality of deformable areas of the cushion component 21.

[0057] The controller 221 can be used to selectively enable one or more of the multiple temperature adjustment sections. The selected temperature adjustment section can also be referred to as a target temperature adjustment section. The multiple heaters 222 can be arranged corresponding to the multiple temperature adjustment sections respectively. Each heater can be responsible for independently adjusting the temperature of the temperature adjustment section where it is located, thereby achieving precise control of the material removal amount in different areas of the first surface S1 of the silicon wafer S.

[0058] Further, in some embodiments of the present disclosure, the controller 221 may also be configured to determine one or more target temperature adjustment parts from the multiple temperature adjustment parts according to the morphology of the first surface S1 of the held silicon wafer S. Accordingly, temperature adjustment of the pad component includes: determining one or more target deformation areas from the multiple deformable areas of the pad component 21 according to the morphology of the first surface S1 of the held silicon wafer S.

[0059] In order to improve the versatility of the polishing head 200, the temperature adjustment module 22 can be set to have more temperature adjustment parts. When the polishing head 200 is used, one or more suitable temperature adjustment parts can be selected from all the temperature adjustment parts as the target temperature adjustment parts according to the specific morphology of the silicon wafer S to be polished, and the selected target temperature adjustment parts can be enabled to perform the temperature adjustment operation on the pad assembly 21, and the unselected temperature adjustment parts can be in a non-working state during the polishing process. As mentioned above, according to the technical idea of ​​the present disclosure, the material removal amount distribution scheme of the silicon wafer can be determined according to the target morphology of the silicon wafer and the initial morphology before polishing. When using the polishing method and polishing equipment provided by the embodiment of the present disclosure, the incoming silicon wafer, that is, before the silicon wafer is polished, can be first subjected to morphology detection. Then, the morphology detection result is compared with the target morphology parameter of the silicon wafer. According to the comparison result, a specific material removal amount distribution scheme can be formulated. Accordingly, a pressure distribution scheme for the silicon wafer in the polishing process to be performed can be obtained.

[0060] According to the embodiment of the present disclosure, by cooperating the controller 221 and the heater 222 in the temperature adjustment module 22 and reasonably selecting the target temperature adjustment part in combination with the specific morphology data, independent heating control of multiple temperature adjustment parts can be achieved, thereby accurately adjusting the pressure applied by the pad assembly 21 to different areas of the silicon wafer S. This control method can not only improve the polishing accuracy and uniformity, but also enhance the flexibility and adaptability of the use of the polishing head 200, thereby improving production efficiency and yield rate.

[0061] In some embodiments of the present disclosure, see Figure 8 The pad assembly 21 may include a pad body 211 and an adsorption pad 212 coupled 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 so that the pad body 211 is deformed, and the adsorption pad 212 is configured to be able to deform into at least partially fit the second surface S2 of the retained silicon wafer S as the pad body 211 is deformed.

[0062] like Figure 8 As shown, the pad body 211 may be disposed adjacent to the temperature adjustment module 22 or in direct contact with the temperature adjustment module 22. The adsorption pad 212 may be disposed on a side of the pad body 211 opposite to the temperature adjustment module 22 and coupled to the pad body 211. The surface of the adsorption pad 212 adjacent to the second surface S2 of the silicon wafer S may be configured to have a shape and size corresponding to the second surface S2 of the silicon wafer S.

[0063] In some embodiments of the present disclosure, the pad body 211 may be made of a material that undergoes a significant shape change but a small volume change when heated, for example, may be made of a shape memory alloy or a shape memory polymer.

[0064] In other embodiments of the present disclosure, the pad body 211 may be made of a thermal expansion material that expands and deforms when heated, such as polyurethane, silicone rubber, etc. When the pad body 211 is locally heated, it may be locally deformed.

[0065] In some embodiments of the present disclosure, the adsorption pad 212 may be made of a flexible material so as to deform when the pad body 211 to which it is combined deforms. The adsorption pad 212 may firmly fix the silicon wafer S on the polishing head 200 by, for example, vacuum adsorption or electrostatic adsorption, to ensure that the silicon wafer S does not slide or fall off the polishing head 200 during the polishing process.

[0066] Since the adsorption pad 26 can be deformed along with the deformation of the pad body 211 , the pad assembly 21 including the adsorption pad 26 can still achieve a desired material removal distribution.

[0067] As an example, the adsorption pad may be made of foamed polyurethane, or a composite material of polyester and polyurethane.

[0068] In some embodiments of the present disclosure, the following silicon wafers can be obtained by using the above-mentioned grinding equipment provided by the embodiments of the present disclosure: the total thickness variation (Total Thickness Variation, TTV) of the silicon wafer is less than 100 nanometers, and the local flatness (Site Flatness, SFQR) is less than 20 nanometers. Table 1 lists the total thickness variation and local flatness of silicon wafers 1# to 5# after being polished using the above-mentioned polishing method provided by the embodiments of the present disclosure.

[0069] Table 1

[0070] It should be noted that the technical solutions described in the embodiments of the present disclosure can be combined arbitrarily without conflict.

[0071] The above is only a specific embodiment of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art who is familiar with the technical field can easily think of changes or substitutions within the technical scope disclosed in the present disclosure, which should be included in the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be based on the protection scope of the claims.

Claims

1. A polishing method, characterized in that: The polishing method comprises: holding a silicon wafer with a polishing head, wherein, with the silicon wafer 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 the pad assembly to at least partially fit the second surface of the held silicon wafer, so that during polishing, the pressure exerted on the pad assembly is transmitted to the silicon wafer via the portion fitting the second surface of the silicon wafer.

2. The polishing method according to claim 1, characterized in that: The cushion assembly includes a plurality of deformable regions that are capable of deforming independently of one another, and temperature regulating the cushion assembly includes temperature regulating each of the plurality of deformable regions of the cushion assembly independently.

3. The polishing method according to claim 2, characterized in that: The temperature regulating the cushion component includes independently heating one or more target deformation regions among the plurality of deformable regions of the cushion component.

4. The polishing method according to claim 3, characterized in that: The temperature regulating the pad assembly includes determining the one or more target deformation regions from the plurality of deformable regions of the pad assembly according to the topography of the first surface of the held silicon wafer.

5. The polishing method according to any one of claims 1 to 4, characterized in that: The pad assembly includes a pad body and an adsorption pad coupled to the pad body for adsorbing a silicon wafer. Correspondingly, the temperature adjustment of the pad assembly so that the pad assembly is deformed to at least partially fit the second surface of the held silicon wafer includes: temperature adjustment of the pad body so that the pad body is deformed and the adsorption pad is deformed to at least partially fit the second surface of the held silicon wafer as the pad body is deformed.

6. A polishing device, characterized in that: The polishing device is used to perform the polishing method according to any one of claims 1 to 5, and the polishing device comprises: a polishing head for holding a silicon wafer, wherein, with the silicon wafer 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 used to adjust the temperature of the pad assembly so that the pad assembly is deformed to at least partially fit the second surface of the held silicon wafer, so that during the polishing process, the pressure exerted on the pad assembly is transmitted to the silicon wafer via the portion where the pad assembly fits the second surface of the silicon wafer.

7. The polishing device according to claim 6, characterized in that: The cushion assembly includes a plurality of deformable regions that can deform independently of each other, and the temperature adjustment module includes a plurality of temperature adjustment portions configured to independently adjust the temperatures of the plurality of deformable regions of the cushion assembly, respectively.

8. The polishing device according to claim 7, characterized in that: At least some of the plurality of temperature adjustment units are disposed at different positions in a radial direction of the held silicon wafer.

9. The polishing device according to claim 8, characterized in that: The plurality of temperature adjustment portions are provided in a plurality of annular shapes arranged concentrically with the held silicon wafer.

10. The polishing device according to any one of claims 6 to 9, characterized in that The pad assembly includes a pad body and an adsorption pad coupled to the pad body for adsorbing a silicon wafer. 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 be deformed into at least partially fitting the second surface of the held silicon wafer as the pad body deforms.

11. A silicon wafer, characterized in that: The silicon wafer is obtained by using the 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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