Polishing head for final polishing, polishing equipment and finished wafer

Abstract

The embodiment of the invention provides a polishing head for final polishing, polishing equipment and a finished wafer, and the polishing head comprises an adsorption ring which is used for being adsorbed on an annular chamfer area of a to-be-polished wafer; and a plurality of connecting elements, each connecting element is movable, and the plurality of connecting elements are connected with the adsorption ring to hold the wafer adsorbed by the adsorption ring, and the plurality of connecting elements are configured to be capable of changing the warping degree or the position of the wafer through respective movement. Therefore, the front surface of the wafer meets the target morphology requirement after being polished.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor wafer production, and in particular to a polishing head, a polishing device and a finished wafer for final polishing. Background Art

[0002] The wafer production process is a key step in semiconductor manufacturing. Its purpose is to produce wafers with high flatness and specific thickness for subsequent integrated circuit manufacturing. The wafer production process mainly includes the following steps: cutting single crystal silicon rods into wafers and performing preliminary grinding to remove the damaged layer caused by cutting; removing the damaged layer and unevenness on the wafer surface through chemical and mechanical actions to achieve the required flatness; removing the residues generated during the polishing process to ensure the cleanliness of the wafer surface; inspecting the flatness, thickness and defects of the wafer, and performing necessary trimming; after the wafer surface reaches a certain flatness, final polishing is performed to meet the requirements of the wafer surface morphology for specific applications. The final polishing process is a crucial step in wafer production, which directly affects the surface quality of the wafer, and thus affects the performance and reliability of subsequent integrated circuits.

[0003] The current wafer final polishing process mainly uses chemical mechanical polishing technology. In this process, the wafer is fixed on the polishing head, which presses the wafer on the rotating polishing pad. The chemical action of the polishing liquid and the mechanical friction of the polishing pad work together to flatten the wafer surface. The polishing liquid usually contains abrasive particles and chemical activators to promote material removal from the wafer surface. During the polishing process, the amount of wafer removal is affected by many factors, including the flow rate and composition of the polishing liquid, the hardness and roughness of the polishing pad, the pressure applied by the polishing head to the wafer, and the temperature and humidity during the polishing process.

[0004] Although chemical mechanical polishing technology has achieved remarkable results in improving the surface flatness of wafers, there are still some problems and challenges. Traditional polishing processes have difficulty controlling the amount of removal in different areas of the wafer, resulting in the inability to meet the specific requirements of different applications for the surface morphology of the wafer. For example, some applications may require the center area of ​​the wafer to be thinner and the edge area to be thicker to accommodate specific device designs. Since the downward pressure of the polishing head on the wafer is mainly concentrated in the center, the amount of removal in the center of the wafer is greater than the amount of removal at the edge, which not only affects the flatness of the wafer, but also limits the uniformity of the wafer thickness. In summary, although the current wafer final polishing technology meets the needs of industrial production to a certain extent, there are still many limitations and challenges, which need to be solved through technological innovation to achieve a more efficient and precise wafer polishing process. Summary of the invention

[0005] To solve the above technical problems, the embodiments of the present disclosure hope to provide a polishing head, a polishing device and a finished wafer for final polishing, which can not only improve the flatness and thickness uniformity of the wafer, but also meet the specific requirements of specific applications for the surface morphology of the wafer.

[0006] The technical solution of the present disclosure is achieved as follows: In a first aspect, an embodiment of the present disclosure provides a polishing head for final polishing, the polishing head comprising: A suction ring, the suction ring being used to be sucked onto the annular chamfered area of ​​the wafer to be polished; and a plurality of connecting elements, each of which is movable, and the plurality of connecting elements are connected to the adsorption ring to hold the wafer adsorbed by the adsorption ring, The plurality of connecting elements are configured to change the warpage or position of the wafer through their respective movements, so that the front side of the wafer meets the target morphology requirement after being polished.

[0007] In a second aspect, an embodiment of the present disclosure provides a polishing device, comprising the polishing head according to the first aspect.

[0008] In a third aspect, an embodiment of the present disclosure provides a finished wafer, wherein the finished wafer is obtained from a wafer undergoing polishing, wherein the polishing of the wafer is completed by the polishing head for final polishing according to the first aspect or the polishing equipment according to the second aspect.

[0009] The embodiment of the present disclosure provides a polishing head, a polishing device and a finished wafer for final polishing, which realizes the control of different parts of the wafer, so that the front side of the wafer can meet specific morphological requirements. Since multiple connecting elements can be displaced relative to each other, the interaction force between different parts of the wafer and the polishing pad can be controlled. This displacement capability allows the polishing pad to apply different pressures to each part of the wafer, thereby generating different polishing rates, so that the removal amount of each part corresponding to different parts in the front side is controlled, thereby enabling the front side of the wafer to meet the target morphological requirements after being polished. By accurately controlling the polishing rate and removal amount of each part, a specific thickness distribution of the front side of the wafer can be achieved, and whether the central area is thinner and the edge area is thicker, or other specific morphological requirements, they can be met by the technical solution of the present disclosure. In addition, since multiple connecting elements are connected to the adsorption ring, and the adsorption ring adsorbs the annular chamfered area of ​​the wafer, direct contact with the back side of the wafer is avoided, thereby reducing the risk of surface damage and contamination, and ensuring the surface quality of the wafer. In summary, the technical solution disclosed in the present invention achieves precise polishing of the front side of the wafer by controlling the positions of different parts of the wafer, meets the requirements of specific applications for the surface morphology of the wafer, improves the flatness and thickness uniformity of the wafer, reduces surface damage and contamination, and brings significant technological progress to the field of semiconductor manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 is a front view schematic diagram of a polishing head for final polishing according to an embodiment of the present disclosure, wherein a plurality of connecting elements are not displaced relative to each other; Figure 2 is a front view schematic diagram of a polishing head for final polishing according to an embodiment of the present disclosure, wherein a first displacement state of a plurality of connecting elements is shown; Figure 3 is a schematic top view of a plurality of connection elements of a polishing head and a corresponding wafer for final polishing according to an embodiment of the present disclosure; Figure 4 is a front view schematic diagram of a polishing head for final polishing according to an embodiment of the present disclosure, wherein a second displacement state of a plurality of connecting elements is shown; Figure 5 is a front view schematic diagram of a polishing head for final polishing according to an embodiment of the present disclosure, wherein a third displacement situation of a plurality of connecting elements is shown; Figure 6 is a front view schematic diagram of a polishing head for final polishing according to an embodiment of the present disclosure; Figure 7 for Figure 6 An enlarged schematic diagram of the components within the dotted box area; Figure 8is a front view schematic diagram of a polishing head for final polishing according to another embodiment of the present disclosure; Fig. 9 is a schematic diagram of a finished wafer according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0011] 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.

[0012] In the field of semiconductor manufacturing, the final polishing process of the wafer is a key step to ensure the surface quality of the wafer. However, there are some technical challenges in the traditional polishing process, which limit the precise control of the wafer surface morphology, thereby affecting the flatness and thickness uniformity of the wafer. Specifically, it is difficult for the traditional polishing process to control the removal amount of different areas of the wafer, resulting in the inability to meet the specific requirements of the wafer surface morphology for different applications. For example, some applications may require the center area of ​​the wafer to be thinner and the edge area to be thicker to accommodate specific device designs. In addition, since the downward pressure of the polishing head on the wafer is mainly concentrated in the center, the removal amount in the center of the wafer is greater than the removal amount at the edge, which not only affects the flatness of the wafer, but also limits the uniformity of the wafer thickness.

[0013] In order to solve these problems, the embodiments of the present disclosure provide a technical solution, which aims to control the removal amount of different areas of the wafer to meet the specific requirements of different applications for the surface morphology of the wafer. Figures 1 to 3 The embodiment of the present disclosure provides a polishing head 1 for final polishing, and the polishing head 1 may include: The adsorption ring 30 is used to be adsorbed on the annular chamfered area R of the wafer W to be polished. Figure 2 More clearly shown in; A plurality of connecting elements 10, each of which is movable, and the plurality of connecting elements 10 are connected to the suction ring 30 to hold the wafer W sucked by the suction ring 30; The polishing pad 20 is used to polish the front side FS of the wafer W. The plurality of connecting elements 10 are configured to change the warpage or position of the wafer W by their respective movements. Specifically, the plurality of connecting elements 10 change the positions of different parts WP of the wafer W in the plane P in which the wafer W is located in the direction D perpendicular to the plane P by displacement relative to each other, so that the front side FS of the wafer W meets the target morphology requirements after being polished. Figure 1 The dotted line schematically shows the plane P in which the wafer W itself is located, and the straight arrow schematically shows the above-mentioned direction D. In addition, as shown by comparison Figure 1 and Figure 2It can be found that the plurality of connecting elements 10 are exemplarily shown to be translated relative to each other along the direction D, more specifically, the connecting element 10 near the center is translated vertically upward relative to the connecting element 10 near the edge. Figure 3 FIG. 5 exemplarily shows that 6 dotted lines divide the wafer W into 16 such different parts WP, so as to facilitate understanding of the meaning of the different parts WP mentioned here.

[0014] The technical solution disclosed in the present invention realizes the control of different parts WP of the wafer W by polishing the polishing head 1, so that the front FS of the wafer W can meet specific morphological requirements. Since the multiple connecting elements 10 can be displaced relative to each other, the interaction force between the different parts WP of the wafer W and the polishing pad 20 can be controlled. This displacement capability allows the polishing pad 20 to apply different pressures to each part WP of the wafer W, thereby generating different polishing rates, so that the removal amount of each part corresponding to the different parts WP in the front FS is controlled, thereby enabling the front FS of the wafer W to meet the target morphological requirements after being polished. By accurately controlling the polishing rate and removal amount of each part WP, a specific thickness distribution of the front FS of the wafer W can be achieved, and whether the central area is thinner and the edge area is thicker, or other specific morphological requirements, they can be met by the technical solution disclosed in the present invention. In addition, since the multiple connecting elements 10 are connected to the adsorption ring 30, and the adsorption ring 30 adsorbs the annular chamfered area R of the wafer W, direct contact with the back of the wafer W is avoided, thereby reducing the risk of surface damage and contamination, and ensuring the surface quality of the wafer W. In summary, the technical solution disclosed in the present invention achieves precise polishing of the front side FS of the wafer W by controlling the positions of different parts WP of the wafer W, meets the requirements of specific applications for the surface morphology of the wafer, improves the flatness and thickness uniformity of the wafer, reduces surface damage and contamination, and brings significant technological progress to the field of semiconductor manufacturing.

[0015] In some embodiments of the present disclosure, see Figure 4 Combined with Figure 1 The plurality of connecting elements 10 can move relative to each other in a direction D perpendicular to a plane P on which the wafer W is located, so that the position of the wafer W changes with respect to the plane P.

[0016] like Figure 4As shown, the front FS of the wafer W may be convex on the left side, that is, the left side is thicker. The technical solution disclosed in the present invention can accurately polish such a convex part on the left side. By adjusting the positions of multiple connecting elements 10, the wafer W is tilted relative to the plane P, so that the convex part on the left side is in targeted contact with the polishing pad 20 during the polishing process, and the additional removal of the convex part on the left side is achieved, and finally the front FS is a plane or the flatness of the front FS is good and the thickness is uniform. Wafer W. In addition, for example, in the case where the wafer W is of uniform thickness not shown in the drawings, the technical solution disclosed in the present invention can also meet the specific morphological requirements that the front FS of the wafer W is concave on the left side or the thickness on the left side is small. Specifically, by moving multiple connecting elements 10 in the direction D perpendicular to the plane P, the wafer W can produce a tilt position change relative to the plane P, so that the contact area and pressure of the left part of the front FS with the polishing pad 20 during the polishing process are precisely controlled, and the specific thickness of the left part is removed, and a wafer W that meets the above-mentioned specific morphological requirements is obtained.

[0017] In some embodiments of the present disclosure, see Figure 1 and Figure 2 The plurality of connection elements 10 can move relative to each other in a direction D perpendicular to a plane P on which the wafer W is located, so that the wafer W undergoes a shape change from a planar state to a curved state.

[0018] like Figure 1 As shown, the wafer W may initially be of uniform thickness or have a flat front side FS. The technical solution disclosed in the present invention can achieve specific morphological requirements of thinning the left and right sides of the wafer W or concave left and right sides of the front side FS. By adjusting the positions of multiple connecting elements 10, the wafer W can undergo a shape change from a planar state to a curved state, so that the left and right sides of the front side FS have more contact with the polishing pad 20 during the polishing process, thereby achieving additional removal of the left and right sides. In addition, in the case where the wafer W is thinner than the middle part of the left and right sides, the technical solution disclosed in the present invention can achieve targeted polishing of the left and right sides of the wafer W. As Figure 2 As shown, multiple connecting elements 10 can move relative to each other in a direction D perpendicular to the plane P, so that the shape of the wafer W changes, so that the left and right sides are subjected to more polishing during the polishing process, and finally a wafer W with a flat front FS or good front FS flatness and uniform thickness is obtained.

[0019] It should be noted that the above-mentioned bending state may refer to Figure 2As shown in the figure, it is similar to the shape of a "bent potato chip", or the left and right sides change their positions relative to the middle instead of the radial edges changing their positions relative to the center as described in detail below. It can also refer to the edge of the wafer W not shown in the figure being wavy, which can be achieved by, for example, moving the plurality of connecting elements 10 up or down every other one, and it is easy to understand that the wafer W can also be Figure 2 The upward protrusion shown in FIG. 1 is opposite, that is, it is downwardly protruding. Thus, various target morphology requirements can be met.

[0020] In some embodiments of the present disclosure, see Figure 5 Combined with Figure 1 The plurality of connecting elements 10 can be deflected relative to the plane P in which the wafer W is located, so that the wafer W undergoes a shape change from a planar state to a bowl-shaped state.

[0021] like Figure 1 As shown, the wafer W may initially be of uniform thickness or the front side FS may be flat. The technical solution disclosed in the present invention can achieve specific morphological requirements of thinning the thickness of the radial edge of the wafer W or concave the radial edge of the front side FS. By adjusting the positions of multiple connecting elements 10, the wafer W can undergo a shape change from a planar state to a bowl-shaped state, so that the radial edge of the front side FS has more contact with the polishing pad 20 during the polishing process, thereby achieving additional removal of the radial edge. In addition, in the case where the central portion of the wafer W is thinner relative to the radial edge, the technical solution disclosed in the present invention can achieve targeted polishing of the radial edge of the wafer W. As shown Figure 5 As shown, the plurality of connecting elements 10 can be deflected relative to each other, causing the wafer W to change in shape, so that the radial edge is subjected to more polishing action during the polishing process, and finally a wafer W with a flat front FS or a front FS with good flatness and uniform thickness is obtained.

[0022] It should be noted that the above-mentioned bending state may refer to Figure 5 As shown in Figure 5 The upward protrusion shown in FIG. 1 is opposite, that is, it is downwardly protruding. Thus, various target morphology requirements can be met.

[0023] In some embodiments of the present disclosure, such as in Figure 1 As shown in FIG. 1 , each of the plurality of connecting elements 10 may be a rod-shaped member whose end is connected to the wafer W. As shown in FIG.

[0024] In this way, it is relatively easy for the connecting element 10 to translate or deflect, and this flexibility provides a basis for the precise polishing of the wafer W. For example, the translation of the end of the rod-shaped member connected to the wafer W can be achieved by setting a retractable mechanism inside the rod-shaped member. For example, each rod-shaped member 10 can be built with a screw mechanism or a pneumatic / hydraulic mechanism so that the rod-shaped member 10 can be extended or shortened as needed. For example, the deflection of the rod-shaped member can be achieved by setting a joint or hinge at the base or middle of the rod-shaped member 10.

[0025] For example, the rod-shaped member may be perpendicular to the wafer W and retractable, in which case the wafer W may be changed in shape, such as in Figure 2 As shown in FIG. 1 , the position of the wafer W can also be changed, such as in FIG. Figure 4 As shown in .

[0026] For example, the upper end of the rod-shaped member is movable, or in other words, the upper end can move on a plane parallel to the wafer W, so that the length direction of the rod-shaped member forms a different angle with respect to the wafer W, thereby causing the wafer W to also change shape, such as in Figure 5 As shown in .

[0027] In some examples of the present disclosure, the number of rod-shaped members may be at least four. In this way, the shape and position change control of the wafer W is made more precise. By adjusting the length or angle of these rod-shaped members, the precise positioning and shape adjustment of the wafer W on the polishing pad 20 can be achieved. The design of at least four rod-shaped members improves the stability of the wafer W during the final polishing process. This stability is essential for achieving the precise shape change required for the wafer W, especially when the wafer W needs to be finely adjusted to meet specific morphology requirements. Through the precise control of at least four rod-shaped members 10, the technical solution of the present disclosure can significantly improve the flatness and thickness uniformity of the wafer W. This uniformity is essential for the subsequent semiconductor manufacturing process because it directly affects the performance and reliability of the device.

[0028] In some embodiments of the present disclosure, see Figure 6, the adsorption ring 30 disposed between the wafer W and the rod-shaped member may be soft. As mentioned above, the adsorption ring 30 is used to adsorb the wafer W by contacting the annular chamfered area R of the wafer W, for example, by vacuum effect. It should be noted that, in this case, the connection between the connecting element 10 and the annular chamfered area R of the wafer W is an "indirect" connection rather than a "direct" connection, or in other words, the connecting element 10 is connected to the annular chamfered area R of the wafer W in a manner that the adsorption ring 30 is disposed between the wafer W and the connecting element 10. In this way, the connecting element 10 causes the adsorption ring 30 to change in shape or position, and due to the adsorption effect of the adsorption ring 30 on the wafer W, the wafer W undergoes a corresponding change in shape or position.

[0029] The annular chamfered area R of the wafer W is a key parameter area and defects such as cracks and scratches are not allowed to occur. The present disclosure effectively avoids scratches that may be caused to the annular chamfered area R during the direct adsorption process by setting a soft adsorption ring 30 between the wafer W and the rod-shaped member. Since the adsorption ring 30 is made of a soft material, it is not easy to cause mechanical damage when it contacts the annular chamfered area R of the wafer W. This design avoids stress concentration caused by adsorption, thereby preventing the deterioration of edge parameters and protecting the quality of the entire silicon wafer. By using the soft adsorption ring 30, the surface quality of the wafer W during the polishing process is significantly improved. The soft nature of the adsorption ring 30 reduces the direct contact pressure on the surface of the wafer W, thereby reducing the risk of surface damage.

[0030] In some embodiments of the present disclosure, see Figure 7 The adsorption ring 30 may include a polyurethane ring 31 and a glass fiber ring 32 , the polyurethane ring 31 contacts the wafer W and adheres to the glass fiber ring 32 , and the rod-shaped member is connected to the glass fiber ring 32 .

[0031] By combining the characteristics of the polyurethane ring 31 and the glass fiber ring 32, efficient and safe adsorption of the wafer W is achieved, while protection of the annular chamfered area R of the wafer W is provided. Specifically, the glass fiber ring 32 has fluid channels that are easily connected to the vacuum source fluid to achieve vacuum adsorption, while the polyurethane ring 31 is porous, capable of vacuum adsorption, and is soft, which enables it to provide protection when in contact with the annular chamfered area R of the wafer W. The soft polyurethane ring 31 reduces mechanical damage to the surface of the wafer W, avoids stress concentration caused by adsorption, and thus protects the quality of the wafer W. By using the polyurethane ring 31, the technical solution disclosed in the present invention reduces the direct contact pressure on the surface of the wafer W during the polishing process, reducing the risk of surface damage. This soft protective layer helps to maintain the surface integrity of the wafer W, especially in the sensitive area of ​​the annular chamfered area R.

[0032] In some embodiments of the present disclosure, see Figure 8 The polishing head 1 may further include a supply unit 40, which includes a plurality of fluid supply pipelines 41 capable of independently controlling temperature, and the plurality of fluid supply pipelines 41 are used to supply fluid F of corresponding temperature to different regions of the wafer W, so that the front side FS of the wafer W meets the target morphology requirements after polishing.

[0033] The polishing rate of chemical mechanical polishing is closely related to the temperature of the wafer W. The present disclosure supplies fluid F of different temperatures to different parts WP of the wafer W through the supply unit 40, thereby adjusting the temperature of different parts WP of the wafer W. This temperature adjustment directly affects the material removal rate during chemical mechanical polishing. By supplying fluid F of different temperatures, the present disclosure can achieve differentiation of material removal rates of different parts WP of the wafer W. For example, a higher temperature fluid F can increase the material removal rate of a specific area, while a lower temperature fluid F can reduce the material removal rate of another area. This differentiated control enables the front FS of the wafer W to meet specific morphological requirements after polishing. By precisely controlling the temperature of the wafer W, the technical solution of the present disclosure can significantly improve the flatness and thickness uniformity of the wafer W. This uniformity is crucial to the subsequent semiconductor manufacturing process because it directly affects the performance and reliability of the device.

[0034] In some embodiments of the present disclosure, the fluid F may be a polishing liquid.

[0035] When the fluid F is a polishing liquid, its formula and composition are carefully selected to minimize adverse effects on the wafer W and avoid the introduction of foreign impurities and contamination when in contact with the wafer W. This design helps to protect the surface quality of the wafer W.

[0036] The embodiments of the present disclosure further provide a polishing device which is not shown in the drawings. The polishing device includes the polishing head 1 according to the aforementioned embodiments of the present disclosure.

[0037] See also Fig. 9 The embodiment of the present disclosure also provides a finished wafer PW, which can be obtained from a wafer W that undergoes polishing, and the polishing of the wafer W is completed by the polishing head 1 for final polishing according to the aforementioned embodiments of the present disclosure or the polishing equipment according to the aforementioned embodiments of the present disclosure.

[0038] It should be noted that the technical solutions described in the embodiments of the present disclosure can be combined arbitrarily without conflict.

[0039] 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 head for final polishing, characterized in that: The polishing head comprises: A suction ring, the suction ring being used to be sucked onto the annular chamfered area of ​​the wafer to be polished; and a plurality of connecting elements, each of which is movable, and the plurality of connecting elements are connected to the adsorption ring to hold the wafer adsorbed by the adsorption ring, The plurality of connecting elements are configured to change the warpage or position of the wafer through their respective movements, so that the front side of the wafer meets the target morphology requirement after being polished.

2. The polishing head for final polishing according to claim 1, characterized in that The plurality of connecting elements move relative to each other in a direction perpendicular to a plane in which the wafer is located, so that the position of the wafer changes with respect to the plane.

3. The polishing head for final polishing according to claim 1, characterized in that: The plurality of connecting elements move relative to each other in a direction perpendicular to a plane in which the wafer is located, so that the wafer undergoes a shape change from a planar state to a curved state.

4. The polishing head for final polishing according to claim 1, characterized in that The plurality of connecting elements are deflected relative to a plane in which the wafer is located, so that the wafer undergoes a shape change from a planar state to a bowl-shaped state.

5. The polishing head for final polishing according to any one of claims 2 to 4, characterized in that: Each of the plurality of connection elements is a rod-shaped member whose end is connected to the wafer.

6. The polishing head for final polishing according to claim 5, characterized in that The adsorption ring includes a polyurethane ring and a glass fiber ring, the polyurethane ring contacts the wafer and adheres to the glass fiber ring, and the rod-shaped member is connected to the glass fiber ring.

7. The polishing head for final polishing according to claim 1, characterized in that: The polishing head also includes a supply unit, which includes a plurality of fluid supply pipelines capable of independently controlling temperature. The plurality of fluid supply pipelines are used to supply fluids of corresponding temperatures to different areas of the wafer so that the front side of the wafer meets the target morphology requirements after polishing.

8. The polishing head for final polishing according to claim 7, characterized in that: The fluid is a polishing liquid.

9. A polishing device, characterized in that: The polishing apparatus comprises a polishing head for final polishing according to any one of claims 1 to 8.

10. A finished wafer, characterized in that: The finished wafer is obtained from a wafer that has been polished, wherein the polishing of the wafer is performed by the polishing head for final polishing according to any one of claims 1 to 8 or the polishing device according to claim 9.

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