A fully automatic polishing method and equipment for silicon wafers with uniform thickness reduction

Abstract

The present invention provides a fully automatic polishing method and device for silicon wafers with uniform thickness reduction. The polishing method includes wafer pasting, where multiple silicon wafers are evenly pasted along the circumference of a ceramic disc by a wafer pasting device and then transferred to the polishing device of the present invention; rough polishing, where a polishing pad grinds and polishes the surface of the silicon wafer, and at the same time, a pressure of 400 - 500 kg is applied to the ceramic disc for 6 - 8 minutes of polishing; medium polishing, where the ceramic disc and the silicon wafer are transferred by a rotating robot for further polishing of the silicon wafer, and a pressure of 200 - 300 kg is applied to the ceramic disc for 6 - 8 minutes of polishing; through continuous polishing operations in multiple processes such as rough polishing, medium polishing, and fine polishing, high-precision thickness reduction is achieved. At the same time, during medium polishing and fine polishing, the pressure of the corresponding parts is reduced or increased according to the thickness reduction amount of different parts of the silicon wafer to ensure that the thickness reduction amount on the surface of the silicon wafer is consistent, thereby ensuring the thickness consistency of the surface of the silicon wafer.

Description

Technical Field

[0001] The present invention relates to the technical field of silicon wafer polishing, and particularly to a fully automatic polishing method and device for silicon wafers with uniform thickness reduction. Background Art

[0002] As the core basic material for semiconductor manufacturing, silicon wafer polishing is a key process aimed at obtaining a smooth, flat and uniformly thick surface to meet the requirements of subsequent chip manufacturing processes. However, traditional silicon wafer polishing methods and devices have many deficiencies. It is difficult to accurately control the material removal rate, resulting in different thickness reduction amounts in different regions of the silicon wafer, which easily causes problems such as deformation of chip circuit patterns and unstable electrical performance, seriously reducing the yield.

[0003] The existing patent CN112652526A discloses a silicon wafer polishing method and a silicon wafer. The silicon wafer polishing method includes the following steps: supplying a polymer to the surface of the silicon wafer to be polished, and simultaneously performing a first polishing on the silicon wafer to be polished; after the first polishing, stopping supplying the polymer to the silicon wafer to be polished, supplying a polishing liquid to the silicon wafer to be polished, and simultaneously performing a second polishing on the silicon wafer to be polished. The silicon wafer polishing method of the embodiment of the present invention includes two stages of the first polishing and the second polishing. Among them, during the first polishing process, a polymer is supplied to the surface of the silicon wafer to be polished. During the first polishing process, when pressing the silicon wafer to be polished through a polishing pad, the polymer is more distributed in the area outside the protrusions and plays a certain role in supporting the polishing pad and protecting the silicon wafer to be polished. Therefore, during the first polishing process, the protrusions are mainly polished, thereby reducing the height of the protrusions, which helps to improve the flatness of the silicon wafer.

[0004] However, during the grinding and polishing process, the thickness changes of the silicon wafers are different, and the edge part is prone to collapse (the thickness reduction amplitude is significantly larger than other positions); secondly, uneven force during the central pressing process or maintaining a constant pressure results in a larger thickness reduction at the edge part finally; finally, the existing polishing liquid seeps out from the center to the outside, resulting in the polishing liquid in the central part being the latest and having the best effect, and it is easy to remove more. Summary of the Invention

[0005] The present invention is to overcome the above-mentioned defects in the prior art and provide a fully automatic polishing method for silicon wafers with uniform thickness reduction. Through continuous polishing operations of multiple processes such as rough polishing, medium polishing, and fine polishing, high-precision thickness reduction is achieved. At the same time, during the medium polishing and fine polishing processes, the pressure of the corresponding parts is reduced or increased according to the thickness reduction amount of different parts of the silicon wafer to ensure that the thickness reduction amount on the surface of the silicon wafer is consistent, thereby ensuring the thickness consistency of the surface of the silicon wafer.

[0006] To achieve the above-mentioned invention object, the present invention adopts the following technical solutions: A fully automatic polishing method for silicon wafers with uniform thickness reduction, comprising the following steps: Step 1, wafer sticking. A plurality of silicon wafers are evenly pasted along the circumference of a ceramic disc through a wafer sticking device, and then transferred to the polishing device of the present invention;

[0007] Step 2, rough polishing. The polishing pad polishes the surface of the silicon wafer, and at the same time applies a pressure of 400 - 500 kg to the ceramic disc for 6 - 8 minutes of polishing;

[0008] Step 3, medium polishing. The ceramic disc and the silicon wafer are transferred by a rotating robot arm for further polishing of the silicon wafer, applying a pressure of 200 - 300 kg to the ceramic disc for 6 - 8 minutes of polishing;

[0009] Step 4, fine polishing. The ceramic disc and the silicon wafer are transferred by a rotating robot arm for the final polishing of the silicon wafer, and at the same time applying a pressure of 100 - 200 kg to the ceramic disc for 6 - 8 minutes of polishing.

[0010] As an improvement, before the wafer sticking step, there is also a rinsing process, with a rinsing speed of 500 ± 50 rpm; a spin - drying speed of 2000 ± 100 rpm; and a spin - drying time of 30 ± 5 s.

[0011] As an improvement, in the wafer sticking step, liquid wax is evenly coated on the surface of the silicon wafer by the method of spinning wax, the liquid wax is evenly dropped on the silicon wafer, and the silicon wafer is rotated and pressed to evenly distribute the liquid wax on the surface of the silicon wafer.

[0012] As an improvement, in the wafer sticking step, after the silicon wafer surface is coated with wax, the silicon wafer is baked, and after the reference surface is determined and the wafer is flipped by a robot arm, it is pressed and pasted onto the pre - heated ceramic disc.

[0013] As an improvement, in the rough polishing, medium polishing, and fine polishing steps, different auxiliary pressure cylinders drive the corresponding moving rings to move, changing the number of pressing blocks contacting the surface of the silicon wafer, so that the outermost pressing block contacting the silicon wafer acts at the center of the silicon wafer, and the innermost pressing block contacting the silicon wafer acts at the maximum outer diameter of the silicon wafer.

[0014] As an improvement, in the medium polishing step, all the pressing blocks contacting the silicon wafer apply a pressure of 260 - 300 kg for 3 - 4 minutes of grinding and polishing; the pressure of the pressing blocks near the edge of the silicon wafer is reduced to 220 - 260 kg of pressure and continues to grind and polish for 3 - 4 minutes.

[0015] As an improvement, in the fine polishing step, all the pressing blocks contacting the silicon wafer apply a pressure of 170 - 180 kg for 3 - 4 minutes of grinding and polishing;

[0016] The pressure of the pressing blocks near the edge of the silicon wafer is reduced to 150 - 170 kg of pressure and continues to grind and polish for 1 - 2 minutes;

[0017] Reduce the pressure of the pressing block near the edge of the silicon wafer to 130-150 kgf, increase the pressure of the pressing block near the center of the silicon wafer to 180-200 kg, and continue grinding and polishing for 1-2 minutes.

[0018] Another object of the present invention is to provide a fully automatic polishing equipment for silicon wafers with uniform thickness reduction in view of the deficiencies of the prior art. Through the grinding and polishing mechanism, during the grinding and polishing process, the area and pressure of the mold pressing on the silicon wafer are adjusted, so that the change in the thickness difference of the silicon wafer is kept within the minimum range, avoiding the problem of collapse of the edge part of the silicon wafer. Secondly, through the liquid spraying mechanism, the polishing liquid seeps out evenly, ensuring that the concentration of the polishing liquid acting on the surface of the silicon wafer is nearly consistent, and improving the thickness reduction accuracy.

[0019] A fully automatic polishing equipment for silicon wafers with uniform thickness reduction, which is applied to a fully automatic polishing method for silicon wafers with uniform thickness reduction, includes: a machine body and

[0020] a grinding and polishing mechanism, which is arranged on the machine body and is used to adjust the pressure applied to different positions of the silicon wafer;

[0021] a liquid spraying mechanism, which is arranged on the machine body and is used to evenly spray the polishing liquid onto the silicon wafer.

[0022] Preferably, the grinding and polishing mechanism includes:

[0023] a main pressure component, which is arranged on the machine body and is used to apply pressure to the center of the ceramic disc;

[0024] a secondary pressure component, which is arranged on the main pressure component and is used to adjust the pressure applied to the edge of the ceramic disc.

[0025] Preferably, the main pressure component includes:

[0026] a main pressure cylinder, and the main pressure component is arranged on the machine body;

[0027] a main shaft, which is arranged on the ejector rod of the main pressure cylinder;

[0028] a bearing, which is sleeved on the main shaft;

[0029] a pressing head, which is rotatably arranged on the main shaft;

[0030] a limiting strip, and multiple limiting strips are arranged along the circumference of the pressing head;

[0031] a pressing block, and multiple pressing blocks are provided and are slidably arranged on the pressing head, and the pressing blocks are slidably connected to each other;

[0032] Limit blocks, a plurality of which are arranged along the circumference of the pressing block, are engaged with the grooves on the pressing block to play a role in limiting and guiding;

[0033] A protective cover is arranged on the pressing block.

[0034] Preferably, the auxiliary pressing assembly includes:

[0035] A moving ring is slidably arranged on the pressing head, and the inner groove of the moving ring is engaged with the limiting strip;

[0036] Auxiliary pressing cylinders are arranged on the pressing head and are symmetrically arranged;

[0037] A connecting block is connected to the ejector rod of the auxiliary pressing cylinder, and the connecting blocks are respectively arranged on different moving rings in sequence;

[0038] Connecting plates are respectively connected to different moving rings and the pressing block at both ends, and multiple groups of connecting plates are arranged along the circumference of the moving ring.

[0039] Preferably, the liquid spraying mechanism includes:

[0040] An infusion tube is arranged on the machine body;

[0041] A connecting pipe is communicated with the bottom of the infusion tube;

[0042] A liquid spraying box is communicated with one end of the connecting pipe, and a long strip-shaped liquid outlet is arranged on one side of the liquid spraying box.

[0043] Preferably, a polishing pad is arranged at the bottom of the machine body, and the polishing pad is driven to rotate by a motor inside the machine body.

[0044] Preferably, a central guide wheel is rotatably arranged at the bottom of the infusion tube, and the central guide wheel rotates passively.

[0045] Preferably, a plurality of side guide wheels are arranged on the machine body, and the side guide wheels rotate passively.

[0046] Preferably, a rotating robot arm is further arranged on the machine body and is used to transfer the ceramic disc and the silicon wafer between different devices.

[0047] Compared with the prior art, the beneficial effects of the present invention are:

[0048] 1. The present invention adaptively and synchronously changes the pressure applied to the surface of the silicon wafer during the grinding and polishing process as the grinding and polishing proceed, thereby ensuring uniform thickness reduction on the surface of the silicon wafer and ensuring the consistency of the silicon wafer thickness, solving the technical problems in the prior art that the pressure cannot be changed all the time and the pressure acting on the surface of the silicon wafer cannot be adjusted in distribution, resulting in inconsistent thickness reduction of the silicon wafer at different rotation speeds and thus affecting the consistency of the silicon wafer thickness.

[0049] 2. The present invention sets up a grinding and polishing mechanism to respectively control the pressure applied by the pressing head and the pressing block to the ceramic disc and the silicon wafer, and when replacing silicon wafers with different diameters, referring to Figure 12 It can be seen that in the prior art, when the diameter of the silicon wafer decreases, in order to place more silicon wafers to achieve higher efficiency, the distance from the center of the silicon wafer to the center of the ceramic disc increases, resulting in the existing pressure grinding tool being unable to completely press the center of the silicon wafer. However, the grinding and polishing mechanism of the present invention can adjust the corresponding pressing area to adapt to silicon wafers with different diameters by selectively pressing some of the pressing blocks.

[0050] 3. Through the grinding and polishing mechanism of the present invention, in addition to being able to adjust the pressing area, the pressure magnitude of each pressing part can also be separately controlled. By referring to Figure 10 the silicon wafer thickness data, increasing the pressure at the thicker part of the silicon wafer can accelerate the reduction of the thickness of the silicon wafer at this position, so as to achieve the effect of uniform thickness reduction of the silicon wafer.

[0051] 4. The present invention sets up a liquid spraying mechanism to change the distribution mode of the polishing liquid, so that the polishing liquid can be evenly distributed and act on the silicon wafer, avoiding the problem that the inner side contacts the polishing liquid first during the flow from the inside to the outside, resulting in more thickness reduction on the inner side.

[0052] In summary, the present invention has the advantages of strong adaptability, good thickness reduction uniformity, and uniform distribution of the polishing liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a schematic diagram of the combined layout structure of multiple devices of the present invention;

[0054] Figure 2 is a schematic diagram of the overall structure of the present invention;

[0055] Figure 3 is a schematic diagram of the liquid spraying box structure of the present invention;

[0056] Figure 4 is a schematic diagram of the grinding and polishing mechanism structure of the present invention;

[0057] Figure 5 is a schematic diagram of the internal structure of the grinding and polishing mechanism of the present invention;

[0058] Figure 6 is a schematic diagram of the pressing block structure of the present invention;

[0059] Figure 7 Schematic diagram of the moving ring structure of the present invention;

[0060] Figure 8 Schematic diagram of the ceramic disc and silicon wafer structures of the present invention;

[0061] Figure 9 Cross-sectional view of the indenter and pressure block of the present invention;

[0062] Figure 10 Thickness distribution diagram of the silicon wafer of the present invention;

[0063] Figure 11 Schematic diagram of the method flow of the present invention;

[0064] Figure 12 Arrangement diagram of silicon wafers of different sizes on the ceramic disc of the present invention;

[0065] Figure 13 Schematic diagram of the state of the pressure block of silicon wafers of different sizes on the silicon wafer surface of the present invention

[0066] Reference numerals: 1, grinding and polishing mechanism; 11, main pressure assembly; 111, main pressure cylinder; 112, main shaft; 113, bearing; 114, indenter; 115, limit strip; 116, pressure block; 117, limit block; 118, protective cover; 12, auxiliary pressure assembly; 121, moving ring; 122, auxiliary pressure cylinder; 123, connecting block; 124, connecting plate;

[0067] 2, liquid spraying mechanism; 201, liquid delivery pipe; 202, connecting pipe; 203, liquid spraying box;

[0068] 3, machine body; 4, polishing pad; 5, rotating robot; 6, ceramic disc; 7, silicon wafer; 8, center guide wheel; 9, edge guide wheel. Detailed implementation manners

[0069] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0070] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0071] In the description of the present invention, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0072] In addition, the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, the meaning of "a plurality" is two or more unless otherwise specifically defined.

[0073] Embodiment 1

[0074] As Figure 11 shown, this embodiment provides a fully automatic polishing method for silicon wafers with uniform thickness reduction, including the following steps:

[0075] Step 1, wafer sticking: Stick multiple silicon wafers 7 evenly along the circumference of the ceramic disk 6 through a wafer sticking device, and then transfer them to the polishing device of the present invention.

[0076] Step 2, rough polishing: The polishing pad 4 polishes the surface of the silicon wafer 7, and at the same time applies a pressure of 400 - 500 kg to the ceramic disk 6 for 6 - 8 minutes of polishing.

[0077] Step 3, medium polishing: Transfer the ceramic disk 6 and the silicon wafer 7 through the rotating robot 5 to further polish the silicon wafer 7, apply a pressure of 200 - 300 kg to the ceramic disk 6 for 6 - 8 minutes of polishing.

[0078] Step 4, fine polishing: Transfer the ceramic disk 6 and the silicon wafer 7 through the rotating robot 5 to perform the final polishing on the silicon wafer 7, and at the same time apply a pressure of 100 - 200 kg to the ceramic disk 6 for 6 - 8 minutes of polishing.

[0079] Preferably, before wafer sticking, the silicon wafer 7 also needs to be rinsed. The rinsing parameters of the silicon wafer 7 are set as follows: rinsing speed 500 ± 50 rpm; spin - drying speed 2000 ± 100 rpm; spin - drying time 30 ± 5 s.

[0080] Preferably, the patch is made by the spin-wax method. Liquid wax is evenly dropped onto the silicon wafer, and the silicon wafer is rotated and pressed to evenly distribute the liquid wax on the surface of the silicon wafer, forming a liquid wax film on the surface of the silicon wafer. The liquid wax selected is imported liquid wax, and different spin-wax process parameters are matched according to the size of the silicon wafer. The specific parameters are shown in Table 1 as follows:

[0081] Table 1. Spin-wax process parameter table corresponding to different silicon wafer sizes

[0082] Wafer size Wax dripping amount per piece (ml) Pressing pressure / kpa Rotational speed rpm Time s 5 inches 0.6±0.2 20 - 30 ka 3000-3500 3-5 6 inches 1.0±0.2 20 - 30 ka 3000-3500 3-5 8 inches 1.2±0.2 20 - 30 ka 3000-3500 3-5

[0083] Preferably, during patching, specifically, after the silicon wafer surface is waxed, it is baked, and after being flipped by the manipulator, it is pressed and attached to the preheated ceramic disc. According to different sizes, the quantity and equal division are carried out. The preheating process parameters of the ceramic disc are shown in Table 2.

[0084] For 5-inch silicon wafers, 8 - 10 pieces per disc; for 6-inch silicon wafers, 6 - 8 pieces per disc; for 8-inch silicon wafers, 4 - 5 pieces per disc.

[0085] Table 2. Preheating process parameter table of ceramic disc

[0086] Baking temperature (°C) Preheating temperature of ceramic plate (°C) 85±5 110±10

[0087] Preferably, the polishing liquid ratio is 1:20 - 1:40, the polishing liquid flow rate is 5 - 10 L / min, the pH value of the polishing liquid is 10 - 11; the polishing rotation speed is 20 - 30 rpm, and the rotation speed of the pressing head: the rotation speed of the polishing pad is around 1:1.

[0088] As an improvement, in the rough polishing, medium polishing, and fine polishing steps, different auxiliary pressure cylinders 122 drive the corresponding moving rings 121 to move, changing the number of pressing blocks 116 in contact with the surface of the silicon wafer, so that the outermost pressing block 116 in contact with the silicon wafer acts on the center of the silicon wafer, and the innermost pressing block 116 in contact with the silicon wafer acts on the maximum outer diameter of the silicon wafer; it should be noted that, as Figure 13 shown, for silicon wafers of different sizes, the number of pressing blocks 116 acting on the silicon wafer is different, ensuring that the outermost pressing block 116 passes through the center of the silicon wafer, and the innermost pressing block 116 exceeds the outer diameter edge of the silicon wafer.

[0089] As an improvement, in the medium polishing step, all the pressing blocks 116 in contact with the silicon wafer are applied with a pressure of 260 - 300 kg, and polished for 3 - 4 minutes; the pressure of the pressing blocks 116 near the edge of the silicon wafer is reduced to 220 - 260 kg pressure, and polished for another 3 - 4 minutes.

[0090] As an improvement, in the fine polishing step, all the pressing blocks 116 in contact with the silicon wafer are applied with a pressure of 170 - 180 kg, and polished for 3 - 4 minutes;

[0091] Reduce the pressure of the pressing block 116 near the edge of the silicon wafer to 150 - 170 kgf, and continue grinding and polishing for 1 - 2 minutes;

[0092] Reduce the pressure of the pressing block 116 near the edge of the silicon wafer to 130 - 150 kgf, and increase the pressure of the pressing block 116 near the center of the silicon wafer to 180 - 200 kg, and continue grinding and polishing for 1 - 2 minutes.

[0093] It should be noted that by changing the pressure at different stages during the fine polishing process, the thickness consistency of the silicon wafer after fine polishing can be ensured, and defects such as collapse at the edge part can be avoided.

[0094] Embodiment 2

[0095] As Figures 1 to 3 shown, this embodiment provides a fully automatic polishing device for silicon wafers with uniform thickness reduction, which is applied to a fully automatic polishing method for silicon wafers with uniform thickness reduction, including: a machine body 3;

[0096] A grinding and polishing mechanism 1, which is arranged on the machine body 3 and is used to adjust the pressure applied to different positions on the silicon wafer 7;

[0097] And a liquid spraying mechanism 2, which is arranged on the machine body 3 and is used to evenly spray polishing liquid onto the silicon wafer 7.

[0098] In this embodiment, by setting the grinding and polishing mechanism 1, the area pressurized on the ceramic disc 6 can be adjusted to adapt to silicon wafers 7 of different size specifications. Secondly, according to the different thickness distributions on the silicon wafer 7, different pressures can be applied at different positions on the ceramic disc 6, so as to obtain a silicon wafer 7 with a uniform thickness distribution. Through the liquid spraying mechanism 2, the polishing liquid can act on the silicon wafer 7 evenly, avoiding the problem that in the prior art, during the flow of the polishing liquid from the inside to the outside, the inner side of the silicon wafer 7 contacts the polishing liquid first, resulting in more thickness reduction on the inner side of the silicon wafer 7.

[0099] It should be noted that when polishing a silicon wafer 7 with a smaller size, more silicon wafers are pasted on the ceramic disc 6, and the distance from the center of the silicon wafer 7 to the center of the ceramic disc 6 becomes larger. In the prior art, the center pressurizes the ceramic disc 6 through a cylinder, so the pressurized area cannot be changed, and the edge is pressurized through a counterweight block, so the pressurizing pressure cannot be changed, which will lead to a reduction in the area of the center pressurizing on the silicon wafer 7 and a decrease in the reliability of pressurizing the silicon wafer 7.

[0100] Furthermore, as Figures 4 to 6 shown, the grinding and polishing mechanism 1 includes:

[0101] A main pressure component 11, which is arranged on the machine body 3 and is used to apply pressure to the center of the ceramic disc 6;

[0102] Auxiliary pressure component 12, the auxiliary pressure component 12 is arranged on the main pressure component 11 and is used to adjust the pressure applied to the edge of the ceramic disc 6.

[0103] In this embodiment, by arranging the main pressure component 11 to pressurize the central position of the ceramic disc 6 and using the auxiliary pressure component 12 to pressurize the edge part of the ceramic disc 6, the pressurizing position on the ceramic disc 6 and the pressure value applied at this position can be freely adjusted, which can adapt to silicon wafers 7 of different sizes. By controlling the pressure magnitudes at different positions on the ceramic disc 6, the friction forces between different positions on the silicon wafer 7 and the polishing pad 4 can be further adjusted, and finally the thickness on the silicon wafer 7 can be controlled to be consistent.

[0104] Further, as Figures 4 to 7 shown, the main pressure component 11 includes:

[0105] Main pressurizing cylinder 111, the main pressure component 11 is arranged on the machine body 3;

[0106] Main shaft 112, the main shaft 112 is arranged on the ejector rod of the main pressurizing cylinder 111;

[0107] Bearing 113, the bearing 113 is sleeved on the main shaft 112;

[0108] Pressure head 114, the pressure head 114 is rotatably arranged on the main shaft 112;

[0109] Limit strip 115, multiple limit strips 115 are arranged along the circumference of the pressure head 114;

[0110] Pressure block 116, multiple pressure blocks 116 are arranged and slidably arranged on the pressure head 114, and the pressure blocks 116 are slidably connected to each other;

[0111] Limit block 117, multiple limit blocks 117 are arranged along the circumference of the pressure block 116, which are engaged with the grooves on the pressure block 116 and play a role in limiting and guiding;

[0112] Protective cover 118, the protective cover 118 is arranged on the pressure block 116.

[0113] In this embodiment, by setting the main pressing component 11, the auxiliary pressing component 12 can be driven to move together to press the ceramic disc 6, so as to apply different pressures at different positions on the ceramic disc 6, enabling the silicon wafer 7 to achieve a uniform thickness reduction effect. When the polishing pad 4 rotates, the silicon wafer 7 in contact with the polishing pad 4 will drive the ceramic disc 6 and the main pressing component 11 to rotate drivenly together, thereby adjusting the position of the silicon wafer 7 on the polishing pad 4. Since the linear velocities at different positions of the polishing pad 4 are different, the thickness reduction of the silicon wafer 7 will be more uniform. The polishing pad 4 and the main pressing component 11 rotate together, which also speeds up the polishing rate of the silicon wafer 7.

[0114] Specifically, the main pressing cylinder 111 drives the main pressing component 11 and the auxiliary pressing component 12 to move downward. The main pressing cylinder 111 also drives the pressing head 114 to press the central position of the ceramic disc 6, and the edge part of the ceramic disc 6 is independently pressed by a plurality of pressing blocks 116. Thus, the pressure distribution on the silicon wafer 7 can be adjusted according to the thickness distribution of the silicon wafer 7 to achieve a uniform thickness reduction effect of the silicon wafer 7.

[0115] It should be noted that the friction during rotation between the main shaft 112 and the pressing head 114 is reduced by the bearing 113. The limiting strip 115 functions to limit the position of the pressing block 116 and provide guidance. The limiting block 117 is used to limit the positions of the pressing blocks 116 relative to each other and provide guidance, and can rotate drivenly together with the pressing head 114.

[0116] Furthermore, as Figures 4 to 6 and Figure 9 shown, the auxiliary pressing component 12 includes:

[0117] A moving ring 121, which is slidably arranged on the pressing head 114, and the internal groove of the moving ring 121 is engaged with the limiting strip 115;

[0118] An auxiliary pressing cylinder 122, which is arranged on the pressing head 114 and is symmetrically arranged;

[0119] A connecting block 123, which is connected to the ejector rod of the auxiliary pressing cylinder 122, and the connecting block 123 is respectively arranged on different moving rings 121 in sequence;

[0120] A connecting plate 124, the two ends of which are respectively connected to different moving rings 121 and the pressing blocks 116, and a plurality of groups of the connecting plate 124 are arranged along the circumference of the moving ring 121.

[0121] In this embodiment, by providing the auxiliary pressing assembly 12, multiple pressing blocks 116 can be controlled separately. According to the size of the silicon wafer 7, it can be determined whether any one of the pressing blocks 116 presses the ceramic disc 6 and the pressing pressure can be adjusted. This enables different pressure magnitudes to be distributed at different positions on the silicon wafer 7 according to requirements. When a certain position on the silicon wafer 7 is thicker, the pressure at this position can be appropriately increased to accelerate the reduction of the thickness of the silicon wafer 7 at this position, making the thickness distribution on the silicon wafer 7 more uniform.

[0122] Specifically, multiple auxiliary pressing cylinders 122 can control the movement of different moving rings 121 separately. The moving rings 121 transmit the pressure to different pressing blocks 116 through the connecting plates 124, achieving the individual control of any one of the pressing blocks 116 and freely adjusting the pressing pressure of the pressing blocks 116.

[0123] It should be noted that since the auxiliary pressing cylinders 122 are respectively connected to different moving rings 121, the lengths of the respective connecting blocks 123 and the installation positions of the auxiliary pressing cylinders 122 are slightly different.

[0124] Furthermore, as Figure 2 shown, a polishing pad 4 is provided at the bottom of the machine body 3, and the polishing pad 4 is rotated by a motor inside the machine body 3.

[0125] It should be noted that the rotation speed of the polishing pad 4 is approximately 20 - 30 rpm. The rotation of the polishing pad 4 drives the ceramic disc 6 and the polishing mechanism 1 to rotate passively.

[0126] Furthermore, as Figure 3 shown, a center guide wheel 8 is rotatably provided at the bottom of the infusion tube 201, and the center guide wheel 8 rotates passively.

[0127] It should be noted that the center guide wheel 8 rotates passively following the ceramic disc 6. Secondly, the center guide wheel 8 also serves to limit the position of the ceramic disc 6.

[0128] Furthermore, as Figures 2 to 3 shown, a plurality of side guide wheels 9 are provided on the machine body 3, and the side guide wheels 9 rotate passively.

[0129] It should be noted that the side guide wheels 9 rotate passively following the ceramic disc 6 and also cooperate with the center guide wheel 8 to limit the position of the ceramic disc 6 together.

[0130] Furthermore, as Figure 3 、 Figure 8 and 12 shown, a rotating robot arm 5 is also provided on the machine body 3 and is used to transfer the ceramic disc 6 and the silicon wafer 7 between different devices.

[0131] It should be noted that a suction cup for sucking the ceramic disc 6 is provided on the rotating robotic arm 5, and the rotating robotic arm 5 can also be telescopically adjusted in length. The rotating robotic arm 5 is a prior art, and the movement of the ceramic disc 6 and the silicon wafer 7 is achieved through the rotating robotic arm 5, which is not the key point of the present invention, and the specific structure will not be elaborated herein.

[0132] Embodiment III

[0133] As Figure 2 shown, the liquid spraying mechanism 2 includes:

[0134] An infusion tube 201, which is arranged on the machine body 3;

[0135] A connecting tube 202, which is communicated with the bottom of the infusion tube 201;

[0136] A liquid spraying box 203, which is communicated with one end of the connecting tube 202, and a long strip-shaped liquid outlet is arranged on one side of the liquid spraying box 203.

[0137] In this embodiment, by setting the liquid spraying mechanism 2, the polishing liquid flowing from the center to the outside in the prior art is changed to uniformly flow out on the polishing pad 4, and the polishing liquid contacted by the silicon wafer 7 is all equally new, avoiding the problem in the prior art that during the process of the polishing liquid flowing from the inside to the outside, the inner side preferentially contacts the polishing liquid, resulting in more thickness reduction on the inner side.

[0138] Specifically, the polishing liquid enters the liquid spraying box 203 from the infusion tube 201 through the connecting tube 202, and then flows out from the long strip-shaped liquid outlet on the liquid spraying box 203. The polishing liquid uniformly flows onto the polishing pad 4, so that the volume and the degree of newness of the polishing liquid contacted by the silicon wafer 7 are the same.

[0139] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A fully automatic polishing method for silicon wafers with uniform thickness reduction, characterized in that, It includes the following steps: Step 1, chip mounting: Use a chip mounting device to evenly mount multiple silicon wafers (7) along the circumference of the ceramic disc (6), and then transfer them to a polishing device; Step 2, rough polishing: The polishing pad (4) polishes the surface of the silicon wafer (7), and at the same time applies a pressure of 400 - 500 kg to the ceramic disc (6), and polishes for 6 - 8 minutes; Step 3, medium polishing: Use a rotating robotic arm (5) to transfer the ceramic disc (6) and the silicon wafer (7), further polish the silicon wafer (7), apply a pressure of 200 - 300 kg to the ceramic disc (6), and polish for 6 - 8 minutes; Step 4, fine polishing: Use a rotating robotic arm (5) to transfer the ceramic disc (6) and the silicon wafer (7), perform the final polishing on the silicon wafer (7), and at the same time apply a pressure of 100 - 200 kg to the ceramic disc (6), and polish for 6 - 8 minutes; In the rough polishing, medium polishing, and fine polishing steps, different auxiliary pressure cylinders (122) drive the corresponding moving rings (121) to move, changing the number of pressing blocks (116) in contact with the surface of the silicon wafer, so that the outermost pressing block (116) in contact with the silicon wafer acts at the center of the silicon wafer, and the innermost pressing block (116) in contact with the silicon wafer acts at the maximum outer diameter of the silicon wafer.

2. A fully automatic polishing method for a silicon wafer with uniform thickness reduction, as described in claim 1, characterized in that, Before the chip mounting step, there is also a rinsing process, with a brushing speed of 500 ± 50 rpm; a spin - drying speed of 2000 ± 100 rpm; and a spin - drying time of 30 ± 5 s.

3. A fully automatic polishing method for silicon wafers with uniform thickness reduction, characterized in that, In the chip mounting step, liquid wax is evenly coated on the surface of the silicon wafer by the method of spinning wax, the liquid wax is evenly dropped on the silicon wafer, and the silicon wafer is rotated and pressed to evenly distribute the liquid wax on the surface of the silicon wafer.

4. A fully automatic polishing method for silicon wafers with uniform thickness reduction, as claimed in claim 3, wherein In the chip mounting step, after the surface of the silicon wafer is coated with wax, the silicon wafer is baked, and after determining the reference plane and flipping it by the robotic arm, it is pressed and attached to the pre - heated ceramic disc.

5. A fully automatic polishing method for silicon wafers with uniform thickness reduction, characterized in that, In the medium polishing step, a pressure of 260 - 300 kg is applied to all the pressing blocks (116) in contact with the silicon wafer, and grinding and polishing are performed for 3 - 4 minutes; the pressure of the pressing blocks (116) near the edge of the silicon wafer is reduced to 220 - 260 kg, and grinding and polishing continue for 3 - 4 minutes.

6. A fully automatic polishing method for wafers with uniform thickness reduction, as claimed in claim 1, wherein, In the fine polishing step, a pressure of 170 - 180 kg is applied to all the pressing blocks (116) in contact with the silicon wafer, and grinding and polishing are performed for 3 - 4 minutes; the pressure of the pressing blocks (116) near the edge of the silicon wafer is reduced to 150 - 170 kg, and grinding and polishing continue for 1 - 2 minutes; the pressure of the pressing blocks (116) near the edge of the silicon wafer is reduced to 130 - 150 kg, and the pressure of the pressing blocks (116) near the center of the silicon wafer is increased to 180 - 200 kg, and grinding and polishing continue for 1 - 2 minutes.

7. A fully automatic silicon wafer polishing device with uniform thickness reduction, which is used to implement the fully automatic silicon wafer polishing method with uniform thickness reduction according to any one of claims 1-6, and is characterized in that, It includes: A machine body (3) and a grinding and polishing mechanism (1), the grinding and polishing mechanism (1) is arranged on the machine body (3) and is used to adjust the pressure applied to different positions on the silicon wafer (7); a liquid spraying mechanism (2), the liquid spraying mechanism (2) is arranged on the machine body (3) and is used to uniformly spray the polishing liquid on the silicon wafer (7); the grinding and polishing mechanism (1) includes: a main pressure component (11), the main pressure component (11) is arranged on the machine body (3) and is used to apply pressure to the center of the ceramic disc (6); a secondary pressure component (12), the secondary pressure component (12) is arranged on the main pressure component (11) and is used to adjust the pressure applied to the edge of the ceramic disc (6).

8. An automatic polishing device for silicon wafers with uniform thickness reduction, according to claim 7, characterized in that, The main pressure component (11) includes: A main pressurizing cylinder (111), the main pressure component (11) is arranged on the machine body (3); A main shaft (112), the main shaft (112) is arranged on the push rod of the main pressurizing cylinder (111); A pressure head (114), the pressure head (114) is rotatably arranged on the main shaft (112); Limit strips (115), multiple limit strips (115) are arranged along the circumference of the pressure head (114); Pressure blocks (116), multiple pressure blocks (116) are provided and are slidably arranged on the pressure head (114), and the pressure blocks (116) are slidably connected to each other; Limit blocks (117), multiple limit blocks (117) are arranged along the circumference of the pressure block (116), and are engaged with the grooves on the pressure block (116) to play a role of limiting and guiding; A protective cover (118), the protective cover (118) is arranged on the pressure block (116).

9. The fully automatic polishing equipment for silicon wafers with uniform thickness reduction according to claim 8, characterized in that, The secondary pressure component (12) includes: A moving ring (121), the moving ring (121) is slidably arranged on the pressure head (114), and the inner groove of the moving ring (121) is engaged with the limit strip (115); Secondary pressurizing cylinders (122), the secondary pressurizing cylinders (122) are arranged on the pressure head (114) and are symmetrically arranged; Connecting blocks (123), the connecting blocks (123) are connected to the push rods of the secondary pressurizing cylinders (122), and the connecting blocks (123) are respectively arranged on different moving rings (121) in sequence; Connecting plates (124), both ends of the connecting plate (124) are respectively connected to different moving rings (121) and the pressure blocks (116), and multiple groups of connecting plates (124) are arranged along the circumference of the moving ring (121).

Images