A carrier and apparatus for double-sided polishing of silicon wafers.

Abstract

This invention discloses a carrier and apparatus for double-sided polishing of silicon wafers; the carrier includes: a disc-shaped body with a circular opening; and a buffer unit arranged in a ring around the inner circumference of the circular opening of the body, the buffer unit being configured to ensure that the polishing amount of the silicon wafer edge does not exceed the target polishing amount even after being squeezed and deformed.

Description

Technical Field

[0001] This invention relates to the field of semiconductor manufacturing technology, and in particular to a carrier and apparatus for double-sided polishing of silicon wafers. Prior Technology

[0002] In recent years, with the development of the semiconductor industry, higher requirements have been placed on the flatness of silicon wafers. In addition to the Global Backsurface-referenced Ideal plane / Range (GBIR), Site Frontsurface referenced least Squares / Range (SFQR), and Site Backsurface-referenced Ideal plane / Range (SBIR) used as flatness evaluation indicators, the following new indicators have also begun to be used: Roll Off Amount (ROA), also known as Edge Roll Off Amount, and Edge Site Frontsurface referenced least Squares / Range (ESFQR), which are used to evaluate the flatness of silicon wafers; and Z-Height Double Differentiation (ZDD), which is used to evaluate curvature changes.

[0003] Double-sided polishing is one of the most effective methods for achieving localized and global planarization of silicon wafers. However, during double-sided polishing, edge collapse can easily occur due to the stress, movement, and abrasive particle aggregation at the edges of the silicon wafer. Currently, most methods to avoid edge collapse involve improving the polishing pad to mitigate this phenomenon. Summary of the Invention

[0004] In view of this, embodiments of the present invention aim to provide a carrier and apparatus for double-sided polishing of silicon wafers, which can prevent edge collapse during double-sided polishing.

[0005] The technical solution of this invention is implemented as follows: In a first aspect, embodiments of the present invention provide a carrier for double-sided polishing of silicon wafers, the carrier comprising: The body is disc-shaped and has a circular opening; A ring-shaped buffer unit is arranged around the inner circumference of the circular opening of the main body. The buffer unit is constructed so that even after being squeezed and deformed, the polishing amount of the silicon wafer edge does not exceed the target polishing amount.

[0006] Secondly, embodiments of the present invention provide an apparatus for double-sided polishing of silicon wafers, the apparatus comprising: An upper polishing head and a lower polishing head are arranged opposite each other in the upward and downward directions; Polishing pads are respectively set below the upper polishing head and above the lower polishing head; A central gear is installed at the center portion between the upper polishing head and the lower polishing head; An internal gear installed at the periphery between the upper and lower polishing heads; As in any of the aforementioned examples, the vehicle.

[0007] This invention provides a carrier and apparatus for double-sided polishing of silicon wafers. The carrier provided by this invention utilizes different structures of the buffer unit to improve the support effect of the buffer unit during the double-sided polishing process, thereby reducing the compression deformation caused by squeezing, ensuring that the polishing amount of the silicon wafer edge does not exceed the target polishing amount, and avoiding the occurrence of edge collapse. Simple Explanation of the Diagram

[0008] Figure 1 is a rough side sectional view of the structure of a double-sided polishing device in a conventional technical solution; Figure 2 is a top view of the double-sided polishing device shown in Figure 1; Figure 3 is a schematic diagram of the structure of a carrier for double-sided polishing of silicon wafers provided in an embodiment of the present invention; Figure 4 is a schematic diagram of a buffer unit structure provided in an embodiment of the present invention; Figure 5 is a schematic diagram of a buffer unit structure provided in another embodiment of the present invention; Figure 6 is a schematic diagram of a buffer unit structure provided in another embodiment of the present invention; Figure 7 is a general side sectional view of the structure of the double-sided polishing device provided in an embodiment of the present invention. Implementation

[0009] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0010] Referring to Figure 1, which shows a general side sectional view of the structure of the double-sided polishing apparatus 1A. Figure 2 is a top view of the double-sided polishing apparatus 1A shown in Figure 1, wherein Figure 1 is a sectional view along line RR′ in Figure 2. As shown in Figures 1 and 2, the double-sided polishing apparatus 1A includes: An upper polishing head 10 and a lower polishing head 20 are arranged opposite to each other in the vertical direction; Polishing pads 30 are respectively disposed below the upper polishing head 10 and above the lower polishing head 20; A central gear 40 is mounted at the center between the upper polishing head 10 and the lower polishing head 20. Internal gear 50 is mounted on the periphery between the upper polishing head 10 and the lower polishing head 20; Multiple carriers 60A are arranged around the central gear 40. Each carrier 60A includes a body 601 with a circular opening and a ring of rubber 602 arranged around the circular opening. Understandably, the ring of rubber 602 around the opening of the carrier 60A forms a retaining hole 603 to hold the silicon sheet W to be polished. Understandably, the silicon sheet W is clamped between the upper polishing head 10 and the lower polishing head 20 in a state of being installed within the retaining hole 603 of the carrier 60A.

[0011] Furthermore, as shown in Figure 2, the outer peripheral teeth 70 of each carrier 60A mesh with the teeth of the central gear 40 and the internal gear 50. The upper polishing head 10 and the lower polishing head 20 are driven to rotate by a drive device (not shown in the figure), thereby causing each carrier 60A to rotate on its own axis while revolving around the central gear 40. Simultaneously, the silicon sheet W, installed in the holding hole 603, is held on the carrier 60A and its front and back surfaces are polished simultaneously through contact with the polishing pad 30. During the polishing process, polishing fluid is supplied to the polishing pad 30 from a nozzle (not shown in the figure).

[0012] However, since the carrier 60A is usually made of stainless steel, a rubber ring 602 is typically placed around the opening of the carrier 60A to avoid unnecessary wear on the silicon wafer W. However, in practice, it has been found that because the rubber ring 602 is relatively soft, it undergoes compression deformation during double-sided polishing when the pressure generated by the upper polishing head 10 and the lower polishing head 20 compresses the rubber ring 602. This results in an increase in the amount of polishing on the edge of the silicon wafer W, leading to edge collapse.

[0013] Based on the above description, embodiments of the present invention aim to provide a technical solution to improve the edge collapse phenomenon of silicon wafers W by improving the structure of the rubber ring. Referring to Figure 3, it shows a carrier 60 for double-sided polishing of silicon wafers provided by an embodiment of the present invention. The carrier 60 includes: The main body 601 is disc-shaped and has a circular opening; A buffer unit 31 is arranged in a ring shape around the inner circumference of the circular opening of the main body 601. The buffer unit 31 is configured to ensure that the polishing amount of the edge of the silicon wafer W does not exceed the target polishing amount even after being squeezed and deformed.

[0014] For the vehicle 60 shown in FIG3, in some possible embodiments, as shown in FIG4, the buffer unit 31 is configured as a sandwich structure, the sandwich structure buffer unit 31 includes a first sandwich structure 41 and a second sandwich structure 42 that completely wraps around the outer periphery of the first sandwich structure 41.

[0015] In some embodiments described above, the first sandwich structure 41 is made of a hard material, such as carbonitride compounds or alloys like stainless steel or tungsten carbide, while the second sandwich structure 42 is made of a soft material, such as resin or rubber. Thus, during double-sided polishing, the second sandwich structure 42 contacts the edge of the silicon wafer W. When the upper polishing head 10 and the lower polishing head 20 simultaneously polish the silicon wafer W and compress the buffer unit 31, the first sandwich structure 41 can resist the compression from the upper polishing head 10 and the lower polishing head 20, thereby reducing the compression deformation of the second sandwich structure 42 caused by the compression. This prevents the polishing amount of the silicon wafer W edge from exceeding the target polishing amount during double-sided polishing, thus avoiding edge collapse.

[0016] In some embodiments of the above implementation, the sandwich-structured buffer unit 31 is configured such that its height after compression deformation is the same as the target height of the silicon wafer W after edge polishing. Understandably, during double-sided polishing, when the second sandwich structure 42 undergoes compression deformation, to ensure that the polishing amount of the silicon wafer W's edge does not exceed the target polishing amount, and to ensure that the polished silicon wafer W meets the specifications, the sandwich structure is configured such that its height after compression deformation is the same as the target height of the silicon wafer W after edge polishing.

[0017] For the vehicle 60 shown in FIG3, in some possible embodiments, as shown in FIG5, the buffer unit 31 is constructed in a sandwich structure shape, the sandwich structure buffer unit 31 including an intermediate layer structure 51 and an outer layer structure 52 disposed on both sides of the intermediate layer structure 51.

[0018] In some embodiments described above, the intermediate layer structure 51 is made of a hard material, such as carbonitride compounds or alloys like stainless steel or tungsten carbide, while the outer layer structure 52 is made of a soft material, such as resin or rubber. Thus, during double-sided polishing, the outer layer structure 52 contacts the edge of the silicon wafer W. When the upper polishing head 10 and the lower polishing head 20 simultaneously polish the silicon wafer W and compress the buffer unit 31, the intermediate layer structure 51 can resist the compression from the upper polishing head 10 and the lower polishing head 20. This allows the outer layer structure 52 to undergo minimal or no compressive deformation, thereby preventing the polishing amount of the silicon wafer W edge from exceeding the target polishing amount during double-sided polishing and thus avoiding edge collapse.

[0019] In some embodiments described above, the height of the sandwich-structured buffer unit 31 is the same as the target height of the silicon wafer W after polishing its edge. Understandably, during double-sided polishing, when the upper polishing head 10 and the lower polishing head 20 polish the silicon wafer W, the intermediate layer structure 51, being a hard material, can resist the pressure exerted by the upper polishing head 10 and the lower polishing head 20. Simultaneously, to ensure that the polishing amount of the silicon wafer W's edge does not exceed the target polishing amount, and to ensure that the polished silicon wafer W meets the specifications, the height of the sandwich structure is set to be the same as the target height of the silicon wafer W's edge after polishing in the specific implementation process.

[0020] Understandably, for the structure of the buffer unit 31 shown in Figures 4 and 5, the increased polishing amount at the edge of the silicon wafer W can be avoided by reducing its own compression deformation, thereby preventing the occurrence of edge collapse.

[0021] For the carrier 60 shown in Figure 3, in some possible embodiments, as shown in Figure 6, the buffer unit 31 is configured such that the height of the portion 311 in contact with the edge of the silicon wafer W is higher than the height of the body 312 of the buffer unit 31. Understandably, the buffer unit 31 is made of a soft material. In practice, the portion 311 in contact with the edge of the silicon wafer W is compressed and deformed by the upper polishing head 10 and the lower polishing head 20, causing its height to be lower than the height of the edge of the silicon wafer W. This leads to an increase in the amount of polishing required on the edge of the silicon wafer W. Therefore, in this embodiment of the invention, the height of the portion 311 in contact with the edge of the silicon wafer W in the buffer unit 31 is set higher than the height of its body 312. This ensures that even if the portion 311 in contact with the edge of the silicon wafer W in the buffer unit 31 is compressed and deformed during double-sided polishing, the edge collapse phenomenon caused by its height being lower than the height of the edge of the silicon wafer W will not occur.

[0022] In order to achieve a better polishing effect, in some examples of the above-described embodiments, the portion 311 of the buffer unit 31 that contacts the edge of the silicon wafer W is configured such that its height after extrusion deformation is the same as the target height of the edge of the silicon wafer after polishing.

[0023] Understandably, for the structure of the buffer unit 31 shown in Figure 6, since the height of the part 311 in the buffer unit 31 that is in contact with the edge of the silicon wafer W is relatively high, even if it undergoes compression deformation due to pressure during the polishing process, it can ensure that its height after compression deformation is the same as the target height of the edge of the silicon wafer W after polishing. Therefore, it will not affect the polishing amount of the edge of the silicon wafer W, thereby avoiding the occurrence of edge collapse.

[0024] For the carrier 60 provided in the embodiments of the present invention, the different structures of the buffer unit 31 are used to improve the support effect of the buffer unit 31 in the double-sided polishing process, so as to reduce the compression deformation caused by extrusion, thereby ensuring that the polishing amount of the silicon wafer W edge does not exceed the target polishing amount and avoiding the occurrence of edge collapse.

[0025] Referring to Figure 7, it shows an apparatus 1 for double-sided polishing of silicon wafers according to an embodiment of the present invention. The apparatus 1 includes: An upper polishing head 10 and a lower polishing head 20 are arranged opposite to each other in the vertical direction; Polishing pads 30 are respectively disposed below the upper polishing head 10 and above the lower polishing head 20; A central gear 40 is installed at the center portion between the upper polishing head 10 and the lower polishing head 20; An internal gear 50 is installed at the periphery between the upper polishing head 10 and the lower polishing head 20; As in any of the aforementioned examples, vehicle 60.

[0026] It should be noted that the technical solutions described in the embodiments of the present invention can be combined arbitrarily without conflict.

[0027] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention 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 the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of protection of the claims.

[0028] 1: Device 1A: Double-sided polishing device 10: Upper polishing head 20: Lower polishing head 30: Polishing Pad 31: Buffer unit 311: The part where the edges meet 312:Ontology 40: Center Gear 41: First sandwich structure 42: Second sandwich structure 50: Internal gear 51: Intermediate layer structure 52: Outer structure 60, 60A: Vehicle 601:Ontology 602: Rubber ring 603: Retaining Hole 70: Peripheral teeth W: Silicon wafer

Claims

1. A carrier for double-sided polishing of silicon wafers, comprising: The body is disc-shaped and has a circular opening; A ring-shaped buffer unit is arranged around the inner circumference of the circular opening of the main body. This buffer unit is configured to ensure that the polishing amount of the silicon wafer edge does not exceed the target polishing amount even after deformation due to compression. The buffer unit is configured as a sandwich structure, comprising a first sandwich structure and a second sandwich structure completely enclosing the outer periphery of the first sandwich structure. During double-sided polishing, the second sandwich structure contacts the edge of the silicon wafer. When the upper and lower polishing heads simultaneously polish the silicon wafer and compress the buffer unit, the first sandwich structure resists the compression from the upper and lower polishing heads, thereby reducing the compression deformation of the second sandwich structure and preventing the polishing amount of the silicon wafer edge from exceeding the target polishing amount during double-sided polishing, thus avoiding edge collapse. The height of the sandwich-shaped buffer unit after compression deformation is set to be the same as the target height of the silicon wafer edge after polishing.

2. The carrier for double-sided polishing of silicon wafers as described in claim 1, wherein, The first sandwich structure is made of rigid material, and the second sandwich structure is made of soft material.

3. An apparatus for double-sided polishing of silicon wafers, comprising: An upper polishing head and a lower polishing head arranged opposite each other in the upward and downward directions; polishing pads respectively disposed below the upper polishing head and above the lower polishing head; a central gear mounted at the center between the upper polishing head and the lower polishing head; an internal gear mounted at the periphery between the upper polishing head and the lower polishing head; a carrier for double-sided polishing of silicon wafers as described in claim 1 or 2.

Images