Double-sided wafer polishing machine

Abstract

The present invention discloses a double-sided wafer polishing machine, comprising a column and a lower cylinder, the column is connected to a lifting cylinder, an upper cylinder is connected below the lifting cylinder, the upper cylinder is concentric with the lower cylinder, the upper end face of the lower cylinder is rotatably connected to a lower turntable, and the lower end face of the upper cylinder is rotatably connected to an upper turntable; a limit plate is placed on the lower turntable, the limit plate has a central through hole in the center and side through holes around it, and one side of the side through hole is connected to the central through hole; a plurality of connecting rods are connected around the limit plate, and the connecting rods extend out of the lower cylinder; the thickness of the limit plate and the connecting rods is the same and is less than the thickness of the wafer; compared with the prior art, the present invention improves the polishing quality and uniformity, reduces the convoluted overlay deviation, integrates chamfering processing, intelligent liquid supply and temperature control and other functions, and brings significant beneficial effects to the wafer processing industry with its high efficiency, precision and intelligence.

Description

Technical Field

[0001] The invention relates to the technical field of wafer processing, in particular to a double-sided wafer polishing machine. Background Art

[0002] As semiconductor devices have increasingly higher requirements for surface precision, double-sided polishing technology has gradually become a research hotspot. However, existing wafer polishers have some shortcomings in double-sided processing.

[0003] Double-sided polishing machines need to solve the problems of wafer fixation, pressure distribution, and polishing liquid penetration during double-sided processing to ensure that the polishing effect on both sides of the wafer is consistent and uniform. In addition, the position of the wafer of the double-sided polishing machine is difficult to control. During the polishing process, if the wafer remains in a fixed position, due to the wear of the polishing pad, the imperfection of the mechanical structure, or the uneven distribution of the polishing liquid, some areas on the wafer surface may be subjected to excessive pressure, while other areas may be underpressured, which will lead to inconsistent polishing effects on the wafer surface, thereby affecting the overall quality of the product. During the long-term polishing process, fixed lines may be generated on the wafer surface. These lines will not only affect the flatness of the wafer surface, but may also cause gyroscopic scale deviations in the subsequent manufacturing process, that is, the pattern or structure on the wafer will deviate in relative position, affecting the performance and reliability of the device. In addition, after the wafer is cut into pieces, the edges often have defects such as sharpness and burrs, which not only affect the mechanical strength of the wafer, but also easily cause scratches and contamination in the subsequent processing process. Therefore, in the prior art, it is often necessary to perform additional chamfering processes on the wafer, which requires special equipment and process steps, increasing the complexity and cost of semiconductor manufacturing. In addition, different process parameters need to be adjusted for chips of different sizes and materials, which affects the overall production efficiency.

[0004] Therefore, it is necessary to provide a double-sided wafer polishing machine to solve the problems raised in the above background technology. Summary of the invention

[0005] To achieve the above object, the present invention provides the following technical solution: a double-sided wafer polishing machine, comprising a column and a lower cylinder, wherein the column is connected to a lifting cylinder, an upper cylinder is connected below the lifting cylinder, the upper cylinder is concentric with the lower cylinder, the upper end surface of the lower cylinder is rotatably connected to a lower turntable, and the lower end surface of the upper cylinder is rotatably connected to an upper turntable;

[0006] A limiting plate is placed on the lower turntable, the limiting plate has a central through hole in the center and side through holes around it, and one side of the side through hole is connected to the central through hole;

[0007] A plurality of connecting rods are connected around the limiting plate, and the connecting rods extend out of the lower cylinder;

[0008] The limiting plate and the connecting rod have the same thickness and are smaller than the thickness of the wafer.

[0009] Furthermore, as a preference, an annular bracket is arranged above the lower tube, a plurality of telescopic cylinders are connected to the lower part of the bracket via a universal ball, and the piston rod end of each telescopic cylinder is connected to each connecting rod in turn via a universal ball.

[0010] Further, as a preference, a center disk is rotatably provided at the center of the upper surface of the lower turntable, and the center disk is located in the center through hole of the limiting disk.

[0011] Furthermore, as a preference, a driving motor is provided in the lower cylinder, the driving motor is connected to the center gear and the center disk, a plurality of rotatable planetary gears are distributed circumferentially within the lower cylinder, the planetary gears are meshed with the center gear, a gear ring is fixed to the lower surface of the lower turntable, the planetary gears are meshed with the gear ring.

[0012] Furthermore, preferably, a water outlet is provided at the center of the center disk.

[0013] Furthermore, preferably, a drainage groove is provided around the outer wall of the lower cylinder.

[0014] Furthermore, preferably, the side surface of the center disk is a concave arc edge.

[0015] Further, preferably, a groove is provided on the surface of the edge of the side through hole of the limiting plate, a rubber rope is embedded in the groove, and a friction wheel is provided at the end of one of the connecting rods, and the rubber rope is wound around the friction wheel.

[0016] Furthermore, preferably, an intelligent temperature control device is provided on the lower turntable.

[0017] Further, preferably, the upper turntable is equipped with a pressure sensing device.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] In the present invention, the simultaneous polishing of both sides of the wafer is achieved by synchronously rotating the upper turntable and the lower turntable in opposite directions, thereby improving the polishing efficiency. At the same time, the wafer can continuously change its position during the polishing process, effectively avoiding the phenomenon of local over-polishing or under-polishing caused by uneven contact, ensuring that each area on the wafer surface can be polished uniformly and fully, reducing the convoluted overlay deviation, and because the position of the wafer is constantly changing during the polishing process, the formation of fixed lines on the wafer surface is reduced, thereby reducing the risk of convoluted overlay deviation, thereby greatly improving the polishing quality.

[0020] In the present invention, the center disk adopts a diamond grinding wheel and is designed with a concave arc edge. When the side edge of the chip is in contact with the center disk, the friction wheel can make the rubber rope circulate and drive the chip to rotate, and the chamfering process is completed at the same time, which not only simplifies the process flow, but also improves the accuracy and consistency of the chamfering, and lays a good foundation for the subsequent processing and use of the chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the overall structure of a double-sided wafer polishing machine;

[0022] Figure 2 It is a schematic diagram of the projection structure of the lower tube;

[0023] Figure 3 It is a schematic diagram of the cross-sectional structure of the lower cylinder and the upper cylinder;

[0024] Figure 4 It is a schematic diagram of the cross-sectional structure at the through hole on the side of the limit plate;

[0025] In the figure: 1. column; 2. lower cylinder; 21. lower turntable; 3. lifting cylinder; 4. upper cylinder; 41. upper turntable; 5. limit plate; 51. groove; 52. rubber rope; 53. friction wheel; 6. connecting rod; 7. bracket; 8. telescopic cylinder; 9. center plate; 91. water outlet; 10. drainage trough; 11. driving motor; 12. center gear; 13. planetary gear; 14. ring gear. DETAILED DESCRIPTION

[0026] See also Figure 1 and Figure 2 In an embodiment of the present invention, a double-sided wafer polishing machine comprises a column 1 and a lower cylinder 2, wherein the column 1 is connected to a lifting cylinder 3, an upper cylinder 4 is connected below the lifting cylinder 3, the upper cylinder 4 is concentric with the lower cylinder 2, the upper end surface of the lower cylinder 2 is rotatably connected to a lower turntable 21, and the lower end surface of the upper cylinder 4 is rotatably connected to an upper turntable 41;

[0027] A limiting plate 5 is placed on the lower turntable 21, wherein the limiting plate 5 has a central through hole in the center and side through holes around it, and one side of the side through hole is connected to the central through hole;

[0028] A plurality of connecting rods 6 are connected around the limiting plate 5, and the connecting rods 6 extend out of the lower cylinder 2;

[0029] The limiting plate 5 and the connecting rod 6 have the same thickness and are smaller than the thickness of the wafer.

[0030] Polishing pads are installed on the surfaces of the upper turntable 41 and the lower turntable 21, and multiple wafers are placed in the side through holes of the limit plate 5. When the upper cylinder 4 descends to the upper turntable 41 and fits the upper surface of the large wafer, the upper turntable 41 and the lower turntable 21 rotate in opposite directions so that both sides of the wafer can be polished. Since the thickness of the limit plate 5 and the connecting rod 6 is smaller than that of the wafer, the limit plate 5 and the connecting rod 6 will not contact the lower turntable 21 and the upper turntable 41, and the position of the limit plate 5 can be changed by pushing the connecting rod 6.

[0031] In this embodiment, an annular bracket 7 is mounted above the lower cylinder 2, and a plurality of telescopic cylinders 8 are connected to the lower portion of the bracket 7 through a universal ball, and the piston rod end of each telescopic cylinder 8 is sequentially connected to each connecting rod 6 through a universal ball. By controlling the extension and contraction of each telescopic cylinder 8, the limit plate 5 can be moved to any position on the lower turntable 21, so as to achieve precise positioning and movement of the wafer in the X and Y directions, as well as slight rotation adjustment;

[0032] When the upper turntable 41 rotates and polishes the wafer, the position of the wafer can be changed all the time. Since the wafer will constantly change its position during the polishing process, it helps to eliminate local over-polishing or under-polishing caused by uneven contact between the wafer and the polishing pad, and can ensure that each area of ​​the wafer surface can be polished evenly and fully, thereby improving the polishing quality and reducing the generation of fixed lines on the wafer surface and causing convoluted overlay deviations.

[0033] In this embodiment, a center disk 9 is rotatably provided at the center of the upper surface of the lower turntable 21 , and the center disk 9 is located in the center through hole of the limiting disk 5 .

[0034] In this embodiment, a driving motor 11 is provided in the lower cylinder 2, and the driving motor 11 is connected to the central gear 12 and the central disk 9. A plurality of rotatable planetary gears 13 are distributed on the inner circumference of the lower cylinder 2, and the planetary gears 13 are meshed with the central gear 12. A gear ring 14 is fixed to the lower surface of the lower turntable 21, and the planetary gears 13 are meshed with the gear ring 14.

[0035] That is to say, the driving motor 11 can drive the center disk 9 and the lower turntable 21 to rotate in the opposite direction, and the rotation speed of the center disk 9 is high. When the limit disk 5 moves to the point where the chip is in contact with the center disk 9, the center disk 9 can drive the chip to rotate, thereby changing the angle of the chip and allowing the chip to be polished at different angles.

[0036] In this embodiment, a water outlet 91 is provided at the center of the central disk 9. The water outlet 91 is connected to an intelligent liquid supply system, which can adjust the type and flow rate of the grinding liquid according to the polishing progress and the material of the wafer, and disperse the grinding liquid between the lower turntable 21 and the upper turntable 41 by the centrifugal effect when the central disk 9 rotates.

[0037] In this embodiment, a drainage groove 10 is provided around the outer wall of the lower cylinder 2. The grinding liquid between the lower rotating disk 21 and the upper rotating disk 41 flows into the drainage groove 10 and is discharged due to centrifugal action.

[0038] See also Figure 3 In this embodiment, the side surface of the center disk 9 is a concave arc edge, and the center disk 9 is a diamond grinding wheel.

[0039] When the side surface of the center disk 9 is in contact with the wafer, since the side surface of the center disk 9 is an inwardly concave arc edge, the center disk 9 can chamfer the wafer during rotation.

[0040] See also Figure 4 In this embodiment, a groove 51 is provided on the surface of the edge of the side through hole of the limiting plate 5, and a rubber rope 52 is embedded in the groove 51. A friction wheel 53 is provided at the end of one of the connecting rods 6, and the rubber rope 52 is wound around the friction wheel 53 that is rotatably embedded in the connecting rod 6. The friction wheel 53 can be driven to rotate by a motor. In other words, when the wafer is embedded in the side through hole of the limiting plate 5, the rubber rope 52 is attached to the edge of the wafer and is pressed tightly. The friction wheel 53 can make the rubber rope 52 move in a circular motion and drive the wafer to rotate, thereby ensuring that the wafer can be evenly chamfered, and the polishing quality of the wafer surface can be further improved due to the self-rotation of the wafer.

[0041] In this embodiment, an intelligent temperature control device is provided on the lower turntable 21. By heating or cooling the lower turntable 21, the temperature during the polishing process is controlled to reduce the influence of thermal stress on the wafer.

[0042] In this embodiment, the upper turntable 41 is equipped with a pressure sensing device, which can automatically adjust the downward pressure of the lifting cylinder 3 according to the thickness of the wafer to ensure the polishing efficiency.

[0043] The specific implementation includes the following steps:

[0044] The wafers to be polished are sequentially placed in the side through holes of the limiting plate 5;

[0045] Start the lifting cylinder 3 to slowly lower the upper cylinder 4 until the upper turntable 41 is attached to the upper surface of the wafer, ensuring that an appropriate pressure is maintained between the upper turntable 41 and the wafer, and the pressure can be automatically adjusted by the pressure sensing device;

[0046] The intelligent liquid supply system adjusts the type and flow rate of the grinding liquid according to the polishing progress and the wafer material, and sprays it between the lower turntable 21 and the upper turntable 41 through the water outlet 91 of the central disk 9;

[0047] The lower turntable 21 and the upper turntable 41 are started at the same time, and the lower turntable 21 and the upper turntable 41 rotate in opposite directions to achieve double-sided polishing of the wafer, and the center disk 9 also rotates at the same time;

[0048] During the polishing process, the position of the limit plate 5 can be adjusted by the telescopic cylinder 8 as needed, so that the wafer moves evenly on the polishing pad to eliminate the phenomenon of local over-polishing or under-polishing, and the side edge of each wafer is sequentially fitted with the center plate 9. Since the side of the center plate 9 is designed with an inwardly concave arc edge, the friction wheel 53 can make the rubber rope 52 circulate and drive the wafer to rotate, and at the same time complete the chamfering of the wafer;

[0049] When the surface of the wafer reaches the required smoothness, the lower turntable 21 and the upper turntable 41 stop rotating, the lifting cylinder 3 contracts to make the upper cylinder 4 rise and leave the wafer, and the limit plate 5 is moved to a position convenient for removal by the telescopic cylinder 8. The polished wafer is carefully taken out, and the polishing pad and residue in the lower cylinder 2 and the upper cylinder 4 are cleaned.

[0050] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A double-sided wafer polishing machine, comprising a column (1) and a lower cylinder (2), characterized in that: The column (1) is connected to a lifting cylinder (3), an upper cylinder (4) is connected below the lifting cylinder (3), the upper cylinder (4) is concentric with the lower cylinder (2), the upper end surface of the lower cylinder (2) is rotatably connected to a lower turntable (21), and the lower end surface of the upper cylinder (4) is rotatably connected to an upper turntable (41); A limiting plate (5) is placed on the lower rotating plate (21), wherein the limiting plate (5) has a central through hole at its center and side through holes around it, and one side of the side through hole is connected to the central through hole; A plurality of connecting rods (6) are connected around the limiting plate (5), and the connecting rods (6) extend outside the lower cylinder (2); The limiting plate (5) and the connecting rod (6) have the same thickness and are smaller than the thickness of the wafer; An annular bracket (7) is mounted above the lower cylinder (2), and a plurality of telescopic cylinders (8) are connected to the lower portion of the bracket (7) via a universal ball joint, wherein the piston rod end of each telescopic cylinder (8) is sequentially connected to each connecting rod (6) via a universal ball joint; A central disk (9) is rotatably provided at the center of the upper surface of the lower rotating disk (21), and the central disk (9) is located in the central through hole of the limiting disk (5); A groove (51) is provided on the surface of the edge of the side through hole of the limiting plate (5), a rubber rope (52) is embedded in the groove (51), a friction wheel (53) is provided at the end of one of the connecting rods (6), and the rubber rope (52) is wound around the friction wheel (53); A driving motor (11) is provided in the lower cylinder (2), and the driving motor (11) is connected to the central gear (12) and the central disk (9). A plurality of planetary gears (13) are distributed on the inner circumference of the lower cylinder (2) and are arranged to rotate, and the planetary gears (13) are meshed with the central gear (12). A gear ring (14) is fixed on the lower surface of the lower rotating disk (21), and the planetary gears (13) are meshed with the gear ring (14). The center disk (9) is made of a diamond grinding wheel, and the side surface of the center disk (9) is an inwardly concave arc edge.

2. A double-sided wafer polishing machine according to claim 1, characterized in that: A water outlet (91) is provided at the center of the center disk (9).

3. A double-sided wafer polishing machine according to claim 1, characterized in that: A drainage groove (10) is provided around the outer wall of the lower cylinder (2).

4. A double-sided wafer polishing machine according to claim 1, characterized in that: The lower turntable (21) is provided with an intelligent temperature control device.

5. A double-sided wafer polishing machine according to claim 1, characterized in that: The upper turntable (41) is equipped with a pressure sensing device.

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