Polishing method of through silicon via product

Abstract

The invention relates to the technical field of silicon through hole product polishing, in particular to a silicon through hole product polishing method which comprises the following steps that S1, an electrorheological polishing machine, an elastic conductive part, an insulating supporting plate with a through cavity and a workpiece to be polished are determined; s2, the insulating supporting plate is fixed to a workpiece supporting platform of the electrorheological polishing machine; placing the elastic conductive piece into the through cavity; conductive grease is attached to the outer surfaces of the elastic conductive parts; s3, a workpiece to be polished is fixed to the insulating supporting plate; the other end of the elastic conductive piece abuts against one silicon through hole, and the center line of the silicon through hole coincides with the rotation axis of the polishing electrode; s4, reverse electrorheological polishing solution treatment; s5, the polishing electrode is connected with a voltage source anode, and the workpiece supporting platform is connected with a voltage source cathode or grounded; then the polishing electrode is driven to rotate; and S6, the small metal dots on the surface of the to-be-polished workpiece are removed. According to the method, the metal layer can be completely removed under the condition that the insulating layer and the silicon through hole of the workpiece to be polished are not damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of through silicon via product polishing, and more specifically, to a through silicon via product polishing method. Background Art

[0002] At present, an important development direction of high-end chips is to use advanced packaging technology to achieve three-dimensional chip manufacturing to improve chip integration. Chip stacking technology is one of the important means to achieve three-dimensional chip manufacturing. When realizing chip stacking, the interconnection between chips is a major challenge.

[0003] The TSV process is also known as the through silicon via process, which can realize vertical electrical interconnection of through silicon vias. The key steps of this process are manufacturing through silicon vias, filling through silicon vias and CMP planarization. Manufacturing through silicon vias is to make holes on the wafer that penetrate the wafer; filling through silicon vias is to fill these holes with metal materials such as copper and tungsten; CMP planarization is to polish and remove the metal layer remaining on the surface of the wafer after filling by chemical mechanical methods, which is to first corrode and soften the metal layer on the surface of the wafer by chemical corrosion, and then grind and remove the softened metal layer by mechanical grinding. For example, a chemical mechanical polishing pad and a chemical mechanical polishing method disclosed in the prior art include applying a polishing liquid to the working surface of the polishing pad or the surface of the material to be polished, so that the working surface of the polishing pad contacts the surface of the material to be polished, and the polishing pad moves relative to the material to be polished, and the material to be polished is chemically mechanically polished under low pressure or ultra-low pressure.

[0004] Since the integrity of the wafer is directly related to the performance of the chip, it is necessary to ensure that the wafer is not damaged or damaged as little as possible when polishing the wafer. When removing the metal layer on the surface of the wafer, it is necessary to ensure that all excess metal is completely removed to prevent these metals from affecting subsequent manufacturing steps and to avoid metal residues affecting the normal operation of the chip. In the above-mentioned prior art solutions, the hard particles in the polishing liquid and the wear particles of the polishing pad may cause scratches or dents on the insulating layer of the wafer or the metal in the silicon through-hole, thereby adversely affecting the quality of the product. Moreover, the high or uneven corrosion rate of the polishing liquid can easily cause insufficient removal of the metal layer and erosion of the insulating layer of the wafer or the metal in the silicon through-hole. Summary of the invention

[0005] In view of the problem that insufficient metal layer removal and damage to the workpiece insulating layer surface or silicon vias may occur easily when polishing the workpiece in the above-mentioned prior art, the present invention provides a polishing method for silicon via products, characterized in that metal residue can be greatly reduced without damaging the workpiece insulating layer and silicon vias.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0007] A method for polishing a through silicon via product comprises the following steps:

[0008] S1: Identify an electrorheological polishing machine, an elastic conductive member, an insulating support plate with a through cavity, and a workpiece to be polished.

[0009] S2: Fix the insulating support plate on the workpiece support platform of the electrorheological polishing machine, then put the elastic conductive part into the through cavity so that one end of the elastic conductive part is connected to the workpiece support platform of the electrorheological polishing machine; then pour conductive grease into the through cavity so that the outer surface of the elastic conductive part is adhered to the conductive grease.

[0010] S3: Fix the workpiece to be polished on the insulating support plate, and then adjust the position of the polishing electrode of the electrorheological polisher so that its polishing range is sufficient to cover the metal layer on the workpiece to be polished, that is, the polishing electrode can polish all areas of the metal layer after one rotation; and make the other end of the elastic conductive member abut against at least one silicon through hole of the workpiece to be polished, and at least one of the silicon through holes abutted by the elastic conductive member coincides with the rotation axis of the polishing electrode. The elastic conductive member has elasticity and conductivity, and the elastic conductive member can maintain abutment with the silicon through hole of the workpiece to be polished. In order to form an electric field between the polishing electrode of the electrorheological polisher and the metal layer, it is necessary to connect the metal layer to the negative pole of the voltage source or to the ground. One of the more preferred solutions is to connect the silicon through hole to the negative pole of the voltage source or to the ground. Since the metal layer is connected to the silicon through hole, the metal layer can also be connected to the negative pole of the voltage source or to the ground. However, due to the small diameter of the silicon through hole, it is difficult to connect the silicon through hole to the voltage source or to the ground through wires. By using an elastic conductive member and adhering conductive grease to the outer surface of the elastic conductive member, the through silicon via can form a very stable electrical connection with the workpiece support platform of the electrorheological polishing machine through the elastic conductive member and the conductive grease. When the workpiece support platform of the electrorheological polishing machine is connected to the negative pole of the voltage source or grounded, the elastic conductive member, the conductive grease, the through silicon via connected to the elastic conductive member, and the metal layer connected to the through silicon via are also connected to the negative pole of the voltage source or grounded.

[0011] S4: Pour electrorheological polishing liquid on the surface of the workpiece to be polished, so that the electrorheological polishing liquid fills the gap between the workpiece to be polished and the electrorheological polishing electrode. Electrorheological fluid is a smart material. It is a suspension composed of dielectric particles and insulating oil. Under the action of the electric field, the dielectric particles attract each other to form chains. The shear strength of the electrorheological fluid increases with the intensity of the electric field (the maximum can reach several hundred kPa). This change process is very rapid (milliseconds) and continuously controllable; when the electric field is removed, the electrorheological fluid quickly returns to a fluid state. Adding abrasive particles, such as silicon dioxide, aluminum oxide, cerium oxide, etc., to the electrorheological fluid can obtain an electrorheological polishing liquid. The electrorheological polishing liquid in the electric field can be used as a polishing pad.

[0012] S5: Connect the polishing electrode of the electrorheological polishing machine to the positive pole of the voltage source, and connect the workpiece support platform to the negative pole of the voltage source or to the ground, so that the metal layer of the workpiece to be polished is connected to the negative pole of the voltage source or the ground wire, thereby forming an electric field between the polishing electrode of the electrorheological polishing machine and the metal layer of the workpiece to be polished, so that the electrorheological polishing liquid between the polishing electrode of the electrorheological polishing machine and the metal layer forms a flexible polishing head; then drive the polishing electrode of the electrorheological polishing machine to rotate so that the flexible polishing head can grind and polish the metal layer on the surface of the workpiece to be polished.

[0013] S6: removing a small metal dot remaining on the surface of the workpiece to be polished.

[0014] It should be noted that the TSVs described in this specification include a TSV structure and a metal filler inside the TSV structure.

[0015] From the principle of electrorheological polishing, it can be known that the polishing efficiency of electrorheological polishing fluid strongly depends on the shear strength of the flexible polishing head formed by the electrorheological polishing fluid under the electric field. Only when the shear strength of the flexible polishing head is large enough, the metal layer can be removed. According to the characteristics of electrorheological polishing that an external electric field needs to be applied, the method of changing the electric field distribution is adopted to control the removal rate of the electrorheological polishing fluid for conductors and insulators. A higher removal rate selectivity can be obtained, that is, a high polishing removal rate for conductors and a low (negligible) removal rate for the insulating layer. Therefore, the electrorheological polishing method is used to selectively remove the metal layer in the through silicon via manufacturing process without damaging the insulating layer and the through silicon via.

[0016] In the above technical solution, the polishing process can be divided into three situations according to the different objects under the polishing electrode. When the polishing electrode is located above the metal layer, since the polishing electrode is connected to the positive electrode of the voltage source and the metal layer is connected to the negative electrode of the voltage source or grounded, an electric field can be formed between the polishing electrode and the metal layer, and the electrorheological polishing fluid between the polishing electrode and the metal layer can form a flexible polishing head. When the polishing electrode rotates, the flexible polishing head has a strong removal effect on the metal layer. When the polishing electrode is located above the insulating layer of the workpiece to be polished, since the insulating layer cannot conduct electricity, the electric field between the polishing electrode and the insulating layer is so weak that it is almost zero, and the electrorheological polishing fluid between the polishing electrode and the insulating layer cannot form a flexible polishing head and cannot produce a removal effect on the insulating layer. When the metal layer material above a through silicon via that is not connected to an elastic conductive part has been polished clean and the polishing electrode is located above the through silicon via, since the through silicon via is not connected to other areas of the metal layer, the through silicon via is disconnected from the negative pole or ground wire of the voltage source, and thus cannot form a strong electric field with the polishing electrode. The electrorheological polishing fluid between the polishing electrode and the through silicon via cannot form a flexible polishing head and cannot produce a removal effect on the through silicon via.

[0017] It is understandable that, during the polishing process, if the metal layer materials remaining on the surface of the workpiece to be polished can be connected to the negative electrode or ground wire of the voltage source, it is possible to avoid leaving insufficiently polished metal layer materials in certain areas, thereby avoiding "metal islands". Since the removal rate of different areas of the metal layer is proportional to the linear velocity of the flexible polishing head, the removal rate of the area on the metal layer far from the rotation axis of the polishing electrode is relatively large, and the removal rate of the area close to the rotation axis of the polishing electrode is relatively small. Therefore, when different areas of the metal layer are connected to the negative electrode or ground wire of the voltage source, the metal layer will gradually shrink from the outside to the inside during polishing, and finally a small metal dot will remain, which is located at the rotation axis of the polishing electrode. Since at least one of the through silicon vias abutting the elastic conductive member has a center line that coincides with the rotation axis of the polishing electrode, it can be ensured that the remaining metal layer materials of the workpiece to be polished can always be connected to the negative electrode or ground wire of the voltage source, and the aforementioned small metal dot is simultaneously located at the through silicon via abutting the elastic conductive member. In summary, after the workpiece to be polished is polished by the above method, the metal layer on the surface of the workpiece to be polished can be completely removed, avoiding metal residue, and the above method will not damage the insulating layer and silicon through via of the workpiece to be polished during implementation.

[0018] Preferably, in step S1, the workpiece to be polished is a wafer; in step S3, after fixing the workpiece to be polished on the insulating support plate, the polishing electrode of the electrorheological polisher is adjusted so that its rotation axis coincides with the center line of the workpiece to be polished; among the through silicon vias connected to the elastic conductive member, at least one of the through silicon vias coincides with the center line of the workpiece to be polished. In the prior art, most of the workpieces to be polished are wafers. During the polishing process, the metal layer will shrink along the radial direction of the workpiece to be polished toward the center of the workpiece to be polished, and finally leave a small dot at the center of the workpiece to be polished. The small dot remaining in the center of the workpiece to be polished is relatively easy to locate, which is conducive to improving the removal efficiency of the small dot. Moreover, the rotation axis of the polishing electrode, the center line of the workpiece to be polished and the axis of the through silicon via abutting the elastic conductive member are set to coincide, which is conducive to improving the polishing efficiency and polishing uniformity of the workpiece to be polished.

[0019] Preferably, in step S1, the insulating support plate is made of zirconia. The insulating support plate made of zirconia has good heat resistance, and its size will not change substantially when the external temperature changes, and will not cause the position or posture of the workpiece to be polished to change. Moreover, it has excellent wear resistance, high strength, high hardness and good fracture toughness, and can provide stable and reliable support for the workpiece to be polished.

[0020] Preferably, in step S1, the elastic conductive member adopts a spring structure, and the length of the elastic conductive member in the initial state is greater than the height of the through cavity. The spring structure has good elasticity, and its elastic deformation performance after multiple compressions and recovery is still relatively stable, and it is more reliable to use.

[0021] Preferably, in the step S2, the workpiece to be polished is adhered to the insulating support plate.

[0022] Preferably, in step S2, the workpiece to be polished is adhered to the insulating support plate using paraffin wax. Paraffin wax has good adhesion and can stably adhere the workpiece to be polished to the insulating support plate to avoid vibration or positional displacement of the workpiece to be polished during the polishing process. Moreover, paraffin wax can serve as a protective layer to avoid mutual friction between the workpiece to be polished and the insulating support plate. After polishing, the paraffin wax can be easily removed by soaking in hot water or the like, and will not cause damage to the workpiece to be polished.

[0023] Preferably, in step S3, the distance between the polishing electrode of the electrorheological polishing machine and the workpiece to be polished is between 0.1 mm and 1 mm.

[0024] Preferably, in step S4, the electric field strength between the polishing electrode and the polishing electrode of the electrorheological polishing machine is between 1 kV / mm and 4 kV / mm.

[0025] Preferably, in step S6, hydrochloric acid is used to corrode and remove a metal spot remaining on the surface of the workpiece to be polished.

[0026] Preferably, in step S6, a grinding tool is used to grind away a metal dot remaining on the surface of the workpiece to be polished.

[0027] The beneficial effects of the present invention are as follows: a specific connection method is adopted to enable the metal layer remaining on the surface of the workpiece to be polished to form a stable connection with the negative electrode or ground wire of the voltage source, so that the electrorheological polishing liquid can form a flexible polishing head between the polishing electrode of the electrorheological polishing machine and the metal layer. By rotating the polishing electrode, the flexible polishing head can selectively grind and polish the metal layer, which can not only avoid the formation of metal islands, but also will not cause damage to the insulating layer and silicon through vias of the workpiece to be polished; finally, hydrochloric acid or a grinding tool is used to remove the small dots remaining on the surface of the workpiece to be polished after polishing, so that the metal layer on the surface of the workpiece to be polished can be completely removed, which is beneficial to improving the quality and performance of silicon through via products. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a flow chart of a method for polishing a through silicon via product;

[0029] Figure 2 is a schematic diagram of the grounding method of the workpiece to be polished;

[0030] Figure 3 It is a schematic diagram of polishing of a polishing electrode of an electrorheological polishing machine, wherein the arrow points to the rotation direction of the polishing electrode;

[0031] Figure 4 yes Figure 3 Schematic diagram of a top view, wherein the arrow points to the hand direction of the polishing electrode;

[0032] Figure 5 It is a diagram of the change process of the metal layer on the workpiece to be polished during polishing;

[0033] Figure 6 is a schematic diagram of the surface of the workpiece to be polished after polishing;

[0034] Figure 7 yes Figure 6 A magnified schematic diagram of the local A in the middle;

[0035] Figure 8 yes Figure 7 Enlarged schematic diagram of part B in the middle.

[0036] In the attached drawings: 1-polishing electrode; 2-elastic conductive member; 3-insulating support plate; 301-through cavity; 4-workpiece to be polished; 401-through silicon via; 5-paraffin; 6-workpiece support platform; 7-metal layer. DETAILED DESCRIPTION

[0037] The technical solution of the present invention is further described in detail below through specific embodiments and in conjunction with the accompanying drawings:

[0038] Example 1

[0039] This embodiment is a first embodiment of a method for polishing a through silicon via product. Figures 1 to 4 As shown, the method comprises the following steps:

[0040] S1: Identify an electrorheological polisher, an elastic conductive part 2, an insulating support plate 3 with a through cavity 301, and a workpiece 4 to be polished. In this embodiment, a certain wafer is used as the workpiece 4 to be polished, and the substrate of the wafer is silicon with a thickness of 500μm. The insulating layer located above the substrate is silicon oxide with a thickness of 2μm. There are multiple through silicon vias 401 on the workpiece 4 to be polished, and the diameter of the through silicon vias 401 is 50μm and the depth is 502μm. The metal layer 7 is located above the insulating layer of the workpiece 4 to be polished. The width of the polishing electrode 1 of the electrorheological polisher is equal to the diameter of the workpiece 4 to be polished, and the vertical center line of the polishing electrode 1 coincides with the axis of rotation. The elastic conductive part 2 adopts a spring structure.

[0041] S2: Fix the insulating support plate 3 on the workpiece support platform 6 of the electrorheological polishing machine, then put the elastic conductive part 2 into the through cavity 301, so that one end of the elastic conductive part 2 is connected to the workpiece support platform 6 of the electrorheological polishing machine; then pour conductive grease into the through cavity 301 so that the outer surface of the elastic conductive part 2 is adhered to the conductive grease.

[0042] S3: Fix the workpiece 4 to be polished on the insulating support plate 3, and then adjust the position of the polishing electrode 1 of the electrorheological polisher so that its rotation axis coincides with the center line of the workpiece 7 to be polished; and make the other end of the elastic conductive member 2 abut against a through silicon hole 401 of the workpiece 4 to be polished, and the center line of the through silicon hole 401 coincides with the rotation axis of the polishing electrode 1. The elastic conductive member 2 has elasticity and conductivity, and the elastic conductive member 2 can maintain abutment with the through silicon hole 401 of the workpiece 4 to be polished. In order to form an electric field between the polishing electrode 1 of the electrorheological polisher and the metal layer 7, it is necessary to connect the metal layer 7 to the negative pole of the voltage source or to the ground. One of the more preferred solutions is to connect the through silicon hole 401 to the negative pole of the voltage source or to the ground. Since the metal layer 7 is connected to the through silicon hole 401, the metal layer 7 can also be connected to the negative pole of the voltage source or to the ground. However, since the diameter of the through silicon hole 401 is very small, it is difficult for the through silicon hole 401 to be connected to the voltage source or to the ground through a wire. By using the elastic conductive member 2 and adhering conductive grease to the outer surface of the elastic conductive member 2, the through silicon via 401 can form a very stable electrical connection with the workpiece support platform 6 of the electrorheological polishing machine through the elastic conductive member 2 and the conductive grease. When the workpiece support platform 6 of the electrorheological polishing machine is connected to the negative pole of the voltage source or grounded, the elastic conductive member 2, the conductive grease, the through silicon via 401 connected to the elastic conductive member 2, and the metal layer 7 connected to the through silicon via 401 are also connected to the negative pole of the voltage source or grounded.

[0043] S4: Pour electrorheological polishing liquid on the surface of the workpiece 4 to be polished, so that the electrorheological polishing liquid fills the gap between the workpiece 4 to be polished and the electrorheological polishing electrode 1. Electrorheological fluid is a smart material. It is a suspension composed of dielectric particles and insulating oil. Under the action of the electric field, the dielectric particles attract each other to form chains. The shear strength of the electrorheological fluid increases with the intensity of the electric field (the maximum can reach several hundred kPa). This change process is very rapid (milliseconds) and continuously controllable; when the electric field is removed, the electrorheological fluid quickly returns to a fluid state. Adding abrasive particles such as silicon dioxide, aluminum oxide, cerium oxide, etc. to the electrorheological fluid can obtain an electrorheological polishing liquid. The electrorheological polishing liquid in the electric field can be used as a polishing pad.

[0044] S5: Connect the polishing electrode 1 of the electrorheological polisher to the positive electrode of the voltage source, and ground the workpiece support platform 6 at the same time, so that the metal layer 7 of the workpiece 4 to be polished is connected to the ground wire, thereby forming an electric field between the polishing electrode 1 of the electrorheological polisher and the metal layer 7 of the workpiece 4 to be polished, so that the electrorheological polishing liquid between the polishing electrode 1 of the electrorheological polisher and the metal layer 7 forms a flexible polishing head; then drive the polishing electrode 1 of the electrorheological polisher to rotate so that the flexible polishing head can grind and polish the metal layer 7 on the surface of the workpiece 4 to be polished. The change process of the metal layer 7 on the surface of the workpiece 4 to be polished is as follows: Figure 5 shown.

[0045] S6: removing a small metal dot remaining on the surface of the workpiece 4 to be polished.

[0046] It should be noted that the TSVs 401 described in this specification are metal fillers inside the TSV 401 structure.

[0047] Working principle or workflow of this embodiment: In the above technical solution, the polishing process can be divided into three situations according to the different objects under the polishing electrode 1. When the polishing electrode 1 is located above the metal layer 7, since the polishing electrode 1 is connected to the positive electrode of the voltage source and the metal layer 7 is connected to the negative electrode of the voltage source or grounded, an electric field can be formed between the polishing electrode 1 and the metal layer 7, and the electrorheological polishing fluid between the polishing electrode 1 and the metal layer 7 can form a flexible polishing head. When the polishing electrode 1 rotates, the flexible polishing head has a strong removal effect on the metal layer 7. When the polishing electrode 1 is located above the insulating layer of the workpiece 4 to be polished, since the insulating layer cannot conduct electricity, the electric field between the polishing electrode 1 and the insulating layer is so weak that it is almost zero, and the electrorheological polishing fluid between the polishing electrode 1 and the insulating layer cannot form a flexible polishing head and cannot produce a removal effect on the insulating layer. When the metal layer 7 material above a through-silicon via 401 that is not connected to the elastic conductive member 2 has been polished clean and the polishing electrode 1 is located above the through-silicon via 401, since the through-silicon via 401 is not connected to other areas of the metal layer 7, the through-silicon via 401 is disconnected from the ground wire and cannot form a strong electric field with the polishing electrode 1. The electrorheological polishing fluid between the polishing electrode 1 and the through-silicon via 401 cannot form a flexible polishing head and cannot produce a removal effect on the through-silicon via 401.

[0048] It is understandable that during the polishing process, if the metal layer 7 material remaining on the surface of the workpiece 4 to be polished can be connected to the ground wire, it is possible to avoid leaving insufficiently polished metal layer 7 material in certain areas, thereby avoiding "metal islands". Since the removal rate of different areas of the metal layer 7 is proportional to the linear speed of the flexible polishing head, the removal rate of the area on the metal layer 7 far away from the rotation axis of the polishing electrode 1 is relatively large, and the removal rate of the area close to the rotation axis of the polishing electrode 1 is relatively small. Therefore, when different areas of the metal layer 7 are grounded, the metal layer 7 will gradually shrink from the outside to the inside during polishing, and finally a small metal dot will remain. The small dot is located at the silicon-through hole 401 that abuts the elastic conductive member 2. Since the center line of the silicon-through hole 401 abutting the elastic conductive member 2 coincides with the rotation axis of the polishing electrode 1, it can be ensured that the remaining metal layer 7 material of the workpiece 4 to be polished can always be connected to the ground wire. In summary, after the workpiece 4 is polished using the above method, the metal layer 7 on the surface of the workpiece 4 can be completely removed to avoid metal residue, and the above method will not damage the insulating layer and the through silicon via 401 of the workpiece 4 when implemented.

[0049] The effect of this embodiment is verified: Figure 6As shown, it can be seen that only a small metal dot is left on the surface of the workpiece 4 after polishing. Figure 7 and Figure 8 As shown, it can be seen that the insulating layer surface and the through silicon via of the workpiece 4 to be polished have no scratches or dents or other damage.

[0050] The beneficial effects of this embodiment are as follows: a specific connection method is used to form a stable connection between the metal layer remaining on the surface of the workpiece to be polished and the negative electrode or ground wire of the voltage source, so that the electrorheological polishing liquid can form a flexible polishing head between the polishing electrode of the electrorheological polishing machine and the metal layer. The flexible polishing head can selectively grind and polish the metal layer by rotating the polishing electrode, which can not only avoid the formation of metal islands, but also avoid damage to the insulating layer and silicon vias of the workpiece to be polished; finally, hydrochloric acid or a grinding tool is used to remove the small dots remaining on the surface of the workpiece to be polished after polishing, so that the metal layer on the surface of the workpiece to be polished can be completely removed, which is beneficial to improving the quality and performance of silicon via products.

[0051] Example 2

[0052] This embodiment is a second embodiment of a method for polishing a through silicon via product. This embodiment further supplements step S1 to step S4 based on embodiment 1. Figures 2 to 4 As shown, in step S1, the insulating support plate 3 adopts a zirconia structure. The insulating support plate 3 made of zirconia has good heat resistance, and its size will not change substantially when the external temperature changes, and will not cause the position or posture of the workpiece 4 to be polished to change. Moreover, it has excellent wear resistance, high strength, high hardness and good fracture toughness, and can provide stable and reliable support for the workpiece 4 to be polished.

[0053] Furthermore, in step S2, the workpiece 4 to be polished is pasted on the insulating support plate 3 using paraffin wax 5. The paraffin wax 5 has good adhesion and can stably paste the workpiece 4 to be polished on the insulating support plate 3 to avoid vibration or positional displacement of the workpiece 4 to be polished during the polishing process. Moreover, the paraffin wax 5 can serve as a protective layer to avoid mutual friction between the workpiece 4 to be polished and the insulating support plate 3. After the polishing is completed, the paraffin wax 5 can be easily removed by soaking in hot water or the like, and will not cause damage to the workpiece 4 to be polished.

[0054] Further, in step S3, the distance between the polishing electrode 1 of the electrorheological polishing machine and the workpiece 4 to be polished is between 0.1 mm and 1 mm.

[0055] Further, in step S4, the electric field strength between the polishing electrode 1 and the polishing electrode 1 of the electrorheological polishing machine is between 1 kV / mm and 4 kV / mm.

[0056] The other features, working principles and beneficial effects of this embodiment are consistent with those of Embodiment 1.

[0057] Example 3

[0058] This embodiment is a third embodiment of a method for polishing a through silicon via product, and this embodiment further supplements step S6 based on embodiment 1. In step S6, hydrochloric acid is used to corrode and remove a metal dot remaining on the surface of the workpiece 4 to be polished, or a grinding tool is used to grind and remove a metal dot remaining on the surface of the workpiece 4 to be polished.

[0059] The other features, working principles and beneficial effects of this embodiment are consistent with those of Embodiment 2.

[0060] Obviously, the above embodiments of the present invention are merely examples for clearly explaining the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description, and it is not necessary and impossible to list all the implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for polishing a through silicon via product, characterized in that: The following steps are involved: S1: Determine an electrorheological polishing machine, an elastic conductive member (2), an insulating support plate (3) having a through cavity (301), and a workpiece to be polished (4); S2: fixing the insulating support plate (3) on the workpiece support platform (6) of the electrorheological polishing machine, then placing the elastic conductive member (2) into the through cavity (301), so that one end of the elastic conductive member (2) is connected to the workpiece support platform (6) of the electrorheological polishing machine; then pouring conductive grease into the through cavity (301), and making the outer surface of the elastic conductive member (2) adhere to the conductive grease; S3: The workpiece (4) to be polished is fixed on the insulating support plate (3), and the position of the polishing electrode (1) of the electrorheological polishing machine is adjusted so that its polishing range is sufficient to cover the metal layer (7) on the workpiece (4) to be polished, and the other end of the elastic conductive member (2) is in contact with at least one through-silicon via (401) of the workpiece (4) to be polished; and the center line of at least one of the through-silicon vias (401) in contact with the elastic conductive member (2) coincides with the rotation axis of the polishing electrode (1); S4: pouring electrorheological polishing liquid onto the surface of the workpiece to be polished (4), so that the electrorheological polishing liquid fills the gap between the workpiece to be polished (4) and the electrorheological polishing electrode (1); S5: connecting the polishing electrode (1) of the electrorheological polishing machine to the positive electrode of a voltage source, and connecting the workpiece support platform (6) to the negative electrode of the voltage source or to the ground, and then driving the polishing electrode (1) of the electrorheological polishing machine to rotate; S6: removing a metal dot remaining on the surface of the workpiece (4) to be polished.

2. The method for polishing a through silicon via product according to claim 1, characterized in that: In the step S1, the workpiece (4) to be polished is a wafer; in the step S3, after the workpiece (4) to be polished is fixed on the insulating support plate (3), the polishing electrode (1) of the electrorheological polishing machine is adjusted so that its rotation axis coincides with the center line of the workpiece (4) to be polished; and among the through silicon vias (401) connected to the elastic conductive member (2), at least one of the axes coincides with the center line of the workpiece (4) to be polished.

3. The method for polishing a through silicon via product according to claim 1, characterized in that: In the step S1, the insulating support plate (3) adopts a zirconium oxide structure.

4. The method for polishing a through silicon via product according to claim 1, characterized in that: In the step S1, the elastic conductive member (2) adopts a spring structure, and the length of the elastic conductive member (2) in the initial state is greater than the height of the through cavity (301).

5. The method for polishing a through silicon via product according to claim 1, characterized in that: In the step S2, the workpiece to be polished (4) is bonded to the insulating support plate (3).

6. The method for polishing a through silicon via product according to claim 5, characterized in that: In the step S2, the workpiece to be polished (4) is bonded to the insulating support plate (3) using paraffin wax.

7. The method for polishing a through silicon via product according to claim 1, characterized in that: In step S3, the distance between the polishing electrode (1) of the electrorheological polishing machine and the workpiece (4) to be polished is between 0.1 mm and 1 mm.

8. The method for polishing a through silicon via product according to claim 1, characterized in that: In the step S4, the electric field strength between the polishing electrode (1) and the polishing electrode (1) of the electrorheological polishing machine is between 1 kV / mm and 4 kV / mm.

9. A method for polishing a through silicon via product according to any one of claims 1 to 8, characterized in that: In the step S6, hydrochloric acid is used to corrode and remove a metal spot remaining on the surface of the workpiece (4) to be polished.

10. A method for polishing a through silicon via product according to any one of claims 1 to 8, characterized in that: In step S6, a grinding tool is used to grind away a metal dot remaining on the surface of the workpiece (4) to be polished.

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