Wafer thinning apparatus and thinning method

Abstract

The application relates to the technical field of integrated circuit manufacturing, and discloses wafer thinning equipment and a thinning method. The wafer thinning equipment comprises a grinding device and an adsorption platform. The adsorption platform is used for supporting a wafer and driving the wafer to rotate. The grinding device is arranged above the adsorption platform in a lifting mode. The lower part of the grinding device is provided with a grinding wheel used for grinding the wafer. The grinding wheel comprises a base material and a plurality of grinding blocks. The grinding blocks are fixed to the base material through an adhesive layer. The grinding blocks comprise a gel ceramic combination body which has a staggered spiral stacking structure and is used for dispersing stress during grinding. The raw material of the gel ceramic combination body is a ceramic gel bonding agent which comprises calcium carbonate / calcium phosphate composite gel and chitin nanocrystals. The above technical scheme solves the problems of large total thickness deviation of the thinned wafer and easy formation of a subsurface damage layer in the related art.

Description

Technical Field

[0001] This application relates to the field of integrated circuit manufacturing technology, specifically to wafer thinning equipment and thinning methods. Background Technology

[0002] Three-dimensional integrated circuits (3D ICs) are an important technological path for the semiconductor industry to continue Moore's Law and improve chip performance and integration. The core idea is to stack multiple chips or functional layers vertically and achieve interlayer electrical connections through interconnection technologies such as through-silicon vias (TSVs), thereby achieving higher functional density within a limited space.

[0003] Wafer thinning is a key supporting process in 3D IC manufacturing, its main purpose being to reduce the wafer's thickness from its original level to an ultra-thin state suitable for vertical integration. Ultra-thin wafers are the physical basis for achieving 3D stacking and are crucial for optimizing electrical performance and thermal management. As the number of 3D IC stacking layers increases, the requirements for the thinning thickness of individual wafers become increasingly stringent. Simultaneously, 3D IC technology places extremely high demands on the surface quality of the thinned wafer, including excellent Total Thickness Variation (TTV) and extremely low Roughness Average (Ra), to ensure the accuracy, consistency, and stability of subsequent bonding processes.

[0004] To achieve the aforementioned thinning targets, wafer thinning equipment typically utilizes the physical grinding action of grinding wheels to process ultra-thin wafers. Such equipment must have its grinding structure and grinding process precisely designed and controlled to meet the requirements for ultra-thin wafer processing (such as thickness ≤10 μm, TTV ≤1.5 μm, and Ra ≤5 nm) while also considering manufacturing costs and production efficiency.

[0005] Grinding wheels are an important component of the grinding structure in wafer thinning equipment. Currently, ceramic-bonded grinding wheels have significant defects: (1) poor affinity between ceramic binder and abrasive, resulting in insufficient interfacial bonding strength between the two; (2) insufficient internal mechanical strength of ceramic binder. The above defects often lead to the following in the grinding process: (1) abnormal shedding of abrasive particles, which can easily scratch the wafer surface, forming a subsurface damage layer, and may also scratch the chip interconnect structure, causing deterioration of chip electrical performance parameters; (2) a decrease in the overall mechanical properties of the grinding wheel and an increase in the risk of breakage, causing the total thickness deviation (TTV) of the wafer to become out of control after thinning. Summary of the Invention

[0006] This application proposes wafer thinning equipment and thinning method, thereby solving or at least alleviating one or more of the above-mentioned problems and other problems existing in the prior art.

[0007] The technical solution of this application is as follows:

[0008] This application proposes a wafer thinning device, including a grinding device and an adsorption platform, wherein the adsorption platform is used to support the wafer and drive the wafer to rotate.

[0009] The grinding device is raised and lowered above the adsorption platform. The lower part of the grinding device has a grinding wheel for grinding wafers. The grinding wheel includes a substrate and multiple grinding blocks. The grinding blocks are fixed to the substrate by an adhesive layer. The grinding blocks include a gel ceramic composite with a staggered spiral stacked structure to disperse stress during grinding.

[0010] The raw material for the gel-ceramic composite is a ceramic gel binder, which includes calcium carbonate / calcium phosphate composite gel and chitin nanocrystals.

[0011] As a further technical solution, the staggered spiral stacking structure is arranged parallel to the grinding surface.

[0012] As a further technical solution, the mass ratio of the calcium carbonate / calcium phosphate composite gel to chitin nanocrystals is 3:5 to 5:3.

[0013] As a further technical solution, the molar ratio of calcium ions in the calcium carbonate gel to calcium ions in the calcium phosphate gel in the calcium carbonate / calcium phosphate composite gel is 1:0.5~1.

[0014] As a further technical solution, the raw materials of the grinding block include abrasive, ceramic gel binder, and pore-forming agent.

[0015] As a further technical solution, the surface of the abrasive has carboxyl functional groups, which are chemically bonded to calcium ions in the gel ceramic composite.

[0016] As a further technical solution, the average particle size of the abrasive is 0.5~1.0 μm.

[0017] As a further technical solution, the mass ratio of the abrasive, the gel ceramic binder, and the pore-forming agent is 50~70:20~40:10.

[0018] As a further technical solution, the grinding apparatus includes:

[0019] The feeding assembly is vertically connected above the adsorption platform;

[0020] A rotating shaft, driven by the feed assembly for lifting, is connected to the lower end of the rotating shaft.

[0021] As a further technical solution, the adsorption platform includes:

[0022] The worktable has a chuck spindle at the bottom, which drives the worktable to rotate.

[0023] An adsorption disk, disposed on the worktable, is used to adsorb wafers. The adsorption disk can drive the wafers to rotate synchronously under the action of the worktable.

[0024] This application also proposes a thinning method, which uses the aforementioned wafer thinning equipment to perform a wafer thinning process.

[0025] As a further technical solution, the thinning method includes the following steps:

[0026] A100. Adsorb and fix the wafer onto the adsorption platform;

[0027] A200, drives the grinding wheel down to contact the wafer;

[0028] A300: The grinding wheel and the adsorption platform rotate in the same direction, while the grinding wheel is fed downwards. The rotational speed of the grinding wheel is greater than that of the adsorption platform to grind the wafer.

[0029] A400: When the wafer is ground to the target thickness, stop the rotation of the grinding wheel and the adsorption platform, and move the grinding wheel upward to separate it from the wafer;

[0030] A500, removes the adsorption of the wafer and transfers the wafer.

[0031] The beneficial effects of this application are as follows:

[0032] 1. This application provides a wafer thinning device that improves the ceramic binder of the grinding wheel by using calcium carbonate / calcium phosphate composite gel and chitin nanocrystals as gel ceramic binders. The chitin nanocrystals construct a staggered helical structure template by self-assembling into the gel ceramic binder, thereby regulating the biomimetic mineralization process of the inorganic ion co-crosslinked calcium carbonate / calcium phosphate dual components. This achieves precise construction of an organic-inorganic interpenetrating network at the molecular level, significantly increasing the mechanical properties of the grinding wheel. This not only reduces the total thickness deviation and subsurface damage depth of the thinned wafer, but also extends the service life of the grinding wheel, ultimately increasing the operating time of the wafer thinning device and improving the device's WPH (Waste Per Hour).

[0033] 2. In addition, the wafer thinning equipment of this application effectively suppresses excessive stress concentration during the wafer grinding process by utilizing the staggered spiral stacking structure of the gel ceramic binder, making the stress distribution more uniform during the wafer grinding process, avoiding wafer deformation or surface loss caused by stress concentration problems, thereby avoiding the degradation of chip electrical performance caused by grinding damage.

[0034] 3. The wafer thinning equipment containing gel ceramic binder grinding wheel provided in this application can achieve ultra-thin processing of silicon wafers (<10 μm) after wafer thinning, and simultaneously meet the high flatness requirements of TTV. It provides a high-precision and high-reliability grinding solution for three-dimensional integrated chip manufacturing, and significantly improves the quality and efficiency of chip thinning process. Attached Figure Description

[0035] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 This is a schematic diagram of the structure of a wafer thinning apparatus according to one embodiment of this application;

[0037] Figure 2 for Figure 1 Side view of the grinding device and adsorption platform of the wafer thinning equipment;

[0038] Figure 3 A flowchart illustrating the specific steps of the wafer thinning method provided in this application;

[0039] Figure 4 for Figure 2 A schematic diagram of the structure of the grinding wheel in the diagram;

[0040] Figure 5 for Figure 4 A schematic diagram of the cross-section of the grinding block of the medium grinding wheel parallel to the grinding surface;

[0041] Figure 6 for Figure 4 A three-dimensional structural diagram of the grinding block of a medium grinding wheel;

[0042] Figure 7 SEM image of the calcium carbonate / calcium phosphate composite gel prepared in Example 3;

[0043] Figure 8 SEM image of the chitin nanocrystals prepared in Example 3;

[0044] Figure 9 This is a SEM image of the gel ceramic binder prepared in Example 3.

[0045] Reference numerals: 1. Equipment base; 2. Grinding device; 22. Rotary shaft; 23. Grinding wheel; 231. Substrate; 232. Grinding block; 2321. Gel ceramic composite; 2322. Abrasive grain; 2323. Pore; 3. Adsorption platform; 31. Chuck spindle; 32. Worktable; 33. Adsorption disk; 4. Rotary disk. Detailed Implementation

[0046] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0047] To keep the drawings concise, each drawing only schematically shows the parts relevant to the disclosure; these do not represent the actual structure of the product. Furthermore, for ease of understanding, in some drawings, only one of components with the same structure or function is schematically shown, or only one is labeled. In this document, "one" not only means "only one," but can also mean "more than one," and "several" includes "two" and "more than two."

[0048] In this document, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0049] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature being directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature being directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] In the description of this embodiment, terms such as "upper," "lower," "left," and "right" are based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of description and simplification of operation, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0051] Furthermore, in the description of this application, the terms "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0052] It should be understood that, unless the context clearly indicates otherwise, the terms “comprising,” “including,” or “having” as used herein refer to the presence of an element, but do not exclude the presence or addition of one or more other elements. Furthermore, as used herein, “comprising” and / or “including” indicate the presence of shapes, numbers, steps, operations, members, elements, and / or combinations thereof, and do not exclude the presence or addition of one or more other shapes, numbers, operations, elements, and / or combinations thereof.

[0053] In this application, the numerical range indicated by "~" refers to the range of values ​​specified as the lower and upper limits, respectively, before or after the term. When multiple values ​​are mentioned as the upper or lower limit of any numerical range, the range disclosed herein can be understood as a range with any one of the mentioned upper limits as its upper limit and any one of the mentioned lower limits as its lower limit.

[0054] In the following text, the average particle size can be measured using a commercially available laser particle size analyzer.

[0055] Reference Figure 1 and Figure 2 , Figure 1 The image shows a wafer thinning device. Figure 2 for Figure 1 The side view of the grinding device 2 and the adsorption platform 3 of the wafer thinning equipment. The wafer thinning equipment includes a device base 1, on which a rotating disk 4 is provided. Above the rotating disk 4, multiple adsorption platforms 3 are arranged at intervals along the circumference. The rotating disk 4 can rotate around its own central axis to change the position of the adsorption platform 3, so that the wafer supported by the adsorption platform 3 can switch between the rough grinding station, the fine grinding station and the loading and unloading station.

[0056] Furthermore, an upright support is provided at the end of the equipment base 1, and a grinding device 2 is provided on the side of the support. There are two grinding devices 2, corresponding to a rough grinding section and a fine grinding section. The two have similar structures and are equipped with a feed assembly (not shown) that drives the grinding wheel 23 to move up and down and a mechanism that drives the grinding wheel to rotate along the rotating shaft 22. The feed assembly includes a lifting motor (not shown), which is slidably connected to the housing of the rotating shaft through a lead screw. The housing is slidably connected to the side of the column so that the vertical movement of the rotating shaft 22 is realized by the rotation of the lifting motor, thereby changing the position of the grinding wheel 23 relative to the adsorption platform 3.

[0057] An adsorption platform 3 supports and rotates the wafer. A grinding device 2 is positioned above the adsorption platform 3. The lower part of the grinding device 2 has a grinding wheel 23 capable of circumferential rotation to grind the wafer. The grinding wheel 23 includes a substrate 231 and multiple grinding blocks 232. The grinding blocks 232 are fixed to the substrate 231 by an adhesive layer. Each grinding block 232 includes a gel-ceramic composite 2321 with a staggered spiral stacked structure to disperse stress during grinding. The raw material for the gel-ceramic composite 2321 is a ceramic gel binder, comprising calcium carbonate / calcium phosphate composite gel and chitin nanocrystals. The staggered spiral stacked structure is arranged parallel to the grinding surface. The grinding device 2 includes a feed assembly, a rotating shaft 22, and a grinding wheel 23. The grinding blocks 232 in the grinding wheel 23 (… Figure 4 (Shown) This is used for grinding wafers. The grinding wheel 23 can be a cup-shaped grinding wheel, mounted at the lower end of the rotating shaft 22. The rotating shaft 22 is used to rotate the grinding wheel 23 about its axis of rotation. The feed assembly can drive the rotating shaft 22 and the grinding wheel 23 to move up and down synchronously. When the wafer needs to be ground, the grinding wheel 23 moves under the drive of the feed assembly until its bottom surface contacts the surface of the wafer. At this time, both the grinding wheel 23 and the wafer are rotating in the same direction but at different speeds, and the surface of the wafer is ground using the grinding wheel 23. The feed assembly has a known construction and includes, for example, multiple linear guides that guide the movement direction of the rotating shaft 22 and a ball screw-slider mechanism that moves the rotating shaft 22 up and down.

[0058] Figure 4 The diagram shows a schematic of the structure of the grinding wheel 23. The grinding wheel 23 includes a substrate 231 and a plurality of grinding blocks 232 disposed on the surface of the substrate 231 for grinding the wafer. The raw materials of the grinding blocks 232 may include the following components: abrasive, gel ceramic binder and pore-forming agent. The gel ceramic binder includes calcium carbonate / calcium phosphate composite gel and chitin nanocrystals.

[0059] The composition setting of the grinding block 232 in this application can effectively improve the grinding quality of the wafer. Wherein:

[0060] The abrasive can continuously grind the wafer to achieve wafer thinning; the calcium carbonate / calcium phosphate composite gel and chitin nanocrystals together serve as gel ceramic binders, enabling the realization of an organic-inorganic interpenetrating network at the molecular level and forming a staggered spiral structure, which significantly increases the service life of the grinding wheel 23; the pore-forming agent can form pores in the grinding block 232, effectively achieving heat dissipation and chip removal.

[0061] In this application, by improving the material of the grinding wheel 23, not only can efficient, high-precision and high-flatness wafer thinning processing be achieved, but it can also meet the needs of various wafer types, such as 3D stacked chips, wafer-level packaged chips or flip chips.

[0062] In one embodiment of this application, the mass ratio of calcium carbonate / calcium phosphate composite gel to chitin nanocrystals is 1:99 to 99:1, for example, it can be 1:99, 1:9, 1:4, 3:5, 17:23, 1:1, 23:17, 5:3, 4:1, 9:1 or 99:1, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0063] In one embodiment of this application, the mass ratio of calcium carbonate / calcium phosphate composite gel to chitin nanocrystals is 3:5 to 5:3.

[0064] In this application, when the mass ratio of calcium carbonate / calcium phosphate composite gel to chitin nanocrystals is 3:5 to 5:3, the chitin nanocrystals can be uniformly dispersed in the calcium carbonate / calcium phosphate composite gel matrix, ensuring the structural uniformity of the gel ceramic binder and enabling it to play its full role. This further helps to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0065] In one embodiment of this application, the molar ratio of calcium ions in the calcium carbonate gel to calcium ions in the calcium phosphate gel in the calcium carbonate / calcium phosphate composite gel is 1:0.5~1.

[0066] In this application, when the molar ratio of calcium ions in calcium carbonate gel to calcium ions in calcium phosphate gel is 1:0.5~1, it can promote the formation of a uniformly dispersed composite structure of calcium carbonate and calcium phosphate in the gel network, enhance the interfacial forces, reduce phase separation, improve the structural stability and overall mechanical properties of the composite gel, and further help to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0067] In one embodiment of this application, the method for preparing calcium carbonate / calcium phosphate composite gel includes the following steps: mixing calcium carbonate gel and calcium phosphate gel evenly, centrifuging and washing to obtain calcium carbonate / calcium phosphate composite gel.

[0068] In this application, the preparation of calcium carbonate / calcium phosphate composite gel does not require harsh conditions such as high temperature and high pressure. The composite can be achieved by gel mixing and centrifugal washing at room temperature. The process steps are simple and convenient to operate. It can avoid the damage to the intrinsic structure and composite structure of calcium carbonate and calcium phosphate caused by harsh conditions such as high temperature and high pressure. It can make the calcium carbonate / calcium phosphate composite gel more fully exert its binding effect, which helps to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0069] In one embodiment of this application, the centrifugation speed is 5000~10000 rpm, for example, it can be 5000 rpm, 6000 rpm, 7000 rpm, 8000 rpm, 9000 rpm or 10000 rpm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0070] In one embodiment of this application, the washing liquid is anhydrous ethanol.

[0071] In this application, anhydrous ethanol with moderate polarity and strong solubility is used as the washing liquid, which can effectively wash away impurities in the system. At the same time, its low surface tension can penetrate into the interior of the composite gel, enhance the washing effect, significantly reduce the impurity residue rate, ensure the chemical purity and compositional uniformity of the composite gel, and further help to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0072] In one embodiment of this application, the method for preparing calcium carbonate gel includes the following steps: mixing calcium chloride solution and triethylamine, then introducing carbon dioxide gas, the solution changes from colorless and transparent to milky white, and then to light blue, thus obtaining calcium carbonate gel.

[0073] In the preparation of calcium carbonate gel, the calcium chloride solution is obtained by dissolving calcium chloride dihydrate in anhydrous ethanol. The mass-to-volume ratio of calcium chloride dihydrate to anhydrous ethanol is 0.001~0.01 g / mL, for example, 0.001 g / mL, 0.002 g / mL, 0.003 g / mL, 0.004 g / mL, 0.005 g / mL, 0.006 g / mL, 0.007 g / mL, 0.008 g / mL, 0.009 g / mL or 0.01 g / mL, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0074] During the preparation of calcium carbonate gel, the mixing time is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0075] In the preparation of calcium carbonate gel, the mass-to-volume ratio of calcium chloride dihydrate to triethylamine is 0.1~1 g:10 mL, for example, it can be 0.1 g:10 mL, 0.2 g:10 mL, 0.3 g:10 mL, 0.4 g:10 mL, 0.5 g:10 mL, 0.6 g:10 mL, 0.7 g:10 mL, 0.8 g:10 mL, 0.9 g:10 mL or 1 g:10 mL, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0076] In one embodiment of this application, the method for preparing calcium phosphate gel includes the following steps:

[0077] After mixing calcium chloride solution and triethylamine, phosphoric acid solution is added and the mixture is continued to be mixed to obtain calcium phosphate gel.

[0078] In the preparation of calcium phosphate gel, the calcium chloride solution is obtained by dissolving calcium chloride dihydrate in anhydrous ethanol. The mass-to-volume ratio of calcium chloride dihydrate to anhydrous ethanol is 0.00125~0.0125 g / mL, for example, 0.00125 g / mL, 0.0025 g / mL, 0.00375 g / mL, 0.005 g / mL, 0.00625 g / mL, 0.0075 g / mL, 0.00875 g / mL, 0.01 g / mL, 0.01125 g / mL or 0.0125 g / mL, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0079] During the preparation of calcium phosphate gel, the mixing time is 20 to 40 minutes, for example, 20 minutes, 25 minutes, 30 minutes, 35 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0080] In the preparation of calcium phosphate gel, the mass-to-volume ratio of calcium chloride dihydrate to triethylamine is 0.1~1 g:10 mL, for example, it can be 0.1 g:10 mL, 0.2 g:10 mL, 0.3 g:10 mL, 0.4 g:10 mL, 0.5 g:10 mL, 0.6 g:10 mL, 0.7 g:10 mL, 0.8 g:10 mL, 0.9 g:10 mL or 1 g:10 mL, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0081] In one embodiment of this application, chitin nanocrystals are obtained by purifying and centrifuging chitin after hydrolysis in an acidic environment.

[0082] In one embodiment of this application, one or more of citric acid, acetic acid, and oxalic acid are used during hydrolysis.

[0083] In this application, a weakly acidic organic acid is used to hydrolyze chitin, which can reduce the problem of uneven chitin nanocrystal size or decreased crystallinity caused by excessive hydrolysis, ensure the uniformity and integrity of the chitin nanocrystal structure, and help improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0084] In one embodiment of this application, the hydrolysis temperature is 50~70°C and the hydrolysis time is 6~12 h.

[0085] In this application, the hydrolysis temperature of 50~70℃ provides sufficient energy for acidic hydrolysis while avoiding excessive hydrolysis of the crystalline region due to excessively high temperature; the hydrolysis time of 6~12 h provides sufficient time for the amorphous region to be fully hydrolyzed and for the orderly separation of nanocrystals, while avoiding incomplete hydrolysis due to too short a time or secondary agglomeration of chitin nanocrystals due to too long a time, thus ensuring the uniformity of the chitin nanocrystal structure, allowing the chitin nanocrystals to play a more complete role, and further helping to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0086] In one embodiment of this application, the surface of the abrasive has carboxyl functional groups.

[0087] In this application, the abrasive surface can be coated with carboxyl functional groups through acid treatment, with acid immersion being a preferred method. This aims to utilize the active Ca in the gel ceramic binder. 2+ The formation of a strong chemical bond network with the carboxyl functional groups on the abrasive surface not only improves the mechanical properties of the grinding wheel 23, but also reduces the shedding rate of abrasive particles during the wafer thinning process. Ultimately, this achieves the effect of improving the service life of the wafer thinning equipment and reducing the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0088] In one embodiment of this application, the average particle size of the abrasive is 0.5~1.0 μm, for example, it can be 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm or 1.0 μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0089] In one embodiment of this application, the abrasive includes one or more of corundum, silicon carbide, boron carbide, diamond, and boron nitride.

[0090] In this application, the grinding block 232 requires that the abrasive particles have uniform size and certain hardness and strength. The abrasive can be one or more of corundum, silicon carbide, boron carbide, diamond, and boron nitride, preferably diamond. Diamond has extremely high wear resistance and sharpness, which can quickly grind materials. In addition, it has high thermal conductivity and good stability, which can not only dissipate heat quickly and effectively reduce the temperature of the grinding area, but also is not prone to chemical reaction. It also helps to improve the service life of wafer thinning equipment and reduce the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0091] In one embodiment of this application, the pore-forming agent is hollow microspheres.

[0092] In this application, the porous structure inside the grinding wheel is constructed from the inner cavity of hollow microspheres, which can better perform the functions of heat dissipation, chip containment and chip removal. The hollow microspheres can be, for example, alumina hollow microspheres and / or glass hollow microspheres, preferably alumina hollow microspheres.

[0093] In one embodiment of this application, the mass ratio of abrasive, gel ceramic binder and pore-forming agent is 50~70:20~40:10, for example, it can be 50:40:10, 55:35:10, 60:30:10, 65:25:10 or 70:20:10, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0094] In this application, the optimized dosage of each component of grinding block 232 is 50~70:20~40:10 by mass ratio of abrasive, gel ceramic binder and pore-forming agent. This makes the dosage of each component reasonable and gives full play to the synergistic effect between each component. It improves the overall performance of grinding block 232 in terms of grinding force control, adhesion and heat dissipation and chip removal, thereby improving the quality of the wafer after thinning. Specifically, the amount of abrasive used avoids both insufficient abrasive leading to reduced grinding efficiency and excessive abrasive causing the grinding block 232 to become too rigid and brittle to withstand the impact force during grinding, resulting in breakage and chipping. The amount of gel ceramic binder avoids both insufficient gel ceramic binder leading to insufficient strength of the grinding block 232, making it unable to withstand the grinding force during grinding and causing the grinding wheel 23 to malfunction, and excessive gel ceramic binder leading to a decrease in the overall hardness of the grinding block 232, making it difficult to quickly remove wafer thickness during grinding and reducing grinding efficiency. The amount of pore-forming agent avoids both insufficient pore-forming agent leading to difficulties in heat dissipation and chip removal, resulting in chip accumulation that clogs the grinding wheel 23 and reduces grinding effect, and excessive pore-forming agent leading to too many and too large internal pores in the grinding block 232, thereby reducing the strength of the grinding block 232 and causing breakage and cracking during grinding.

[0095] In one embodiment of this application, the grinding apparatus 2 includes:

[0096] The feeding assembly is lifted and connected above the adsorption platform 3;

[0097] The rotating shaft 22 is driven by the feed assembly to move up and down, and the grinding wheel 23 is connected to the lower end of the rotating shaft 22.

[0098] In this application, the feed assembly and the rotary axis 22 work together to ensure the flatness of the wafer surface during grinding. The feed assembly provides a stable vertical feed path for the rotary axis 22 to drive the grinding wheel 23; the rotary axis 22 can control the radial runout to a very small range, ensuring that the grinding wheel 23 maintains uniform contact with the wafer surface throughout the rotation process. The coordinated operation of the feed assembly and the rotary axis 22 results in a thinned wafer with good flatness.

[0099] In one embodiment of this application, the adsorption platform 3 includes:

[0100] The worktable 32 has a chuck spindle 31 at the bottom, which drives the worktable 32 to rotate.

[0101] The adsorption disk 33 is set on the worktable disk 32 and is used to adsorb the wafer. The adsorption disk 33 can drive the wafer to rotate synchronously under the action of the worktable disk 32.

[0102] In this application, during the actual operation of the wafer thinning equipment, the chuck spindle 31, the worktable 32, and the adsorption disk 33 work together to provide stable adsorption for the grinding wheel 23 to grind the wafer. The chuck spindle 31 controls the rotation speed and direction of the worktable 32, which in turn stably drives the adsorption disk 33 and the wafer to rotate synchronously. The adsorption disk 33 always firmly adsorbs the wafer, ensuring that the wafer maintains a stable position even under high-speed rotation. This synergistic effect prevents poor wafer surface flatness caused by wafer displacement during grinding.

[0103] In another embodiment of this application, the wafer thinning equipment may include multiple adsorption platforms 3, which are used to adsorb different wafers. The multiple adsorption platforms 3 are installed on the same rotating disk 4 and are spaced apart in the circumferential direction of the rotating disk 4. The rotating disk 4 can drive the different adsorption platforms 3 to rotate below the grinding device 2, thereby grinding the corresponding wafers.

[0104] like Figure 1 The wafer thinning equipment shown includes three adsorption platforms 3, which are circumferentially spaced on a rotating disk 4. Simultaneously, two grinding devices 2 are provided: one for rough grinding of the wafer and the other for fine grinding. The rotating disk 4 can drive the adsorption platforms 3 to rotate, allowing for sequential rough and fine grinding of the wafers on the same adsorption platform 3, thus improving the wafer grinding efficiency.

[0105] According to another aspect of this application, this application also proposes a wafer thinning method, which uses the above-mentioned wafer thinning equipment to perform wafer thinning processing.

[0106] In one embodiment of this application, such as Figure 3 As shown, the wafer thinning method may include the following steps:

[0107] A100. The wafer is adsorbed and fixed on the adsorption platform 3;

[0108] A200, driving the grinding wheel 23 to move down until it contacts the wafer;

[0109] A300, the grinding wheel 23 and the adsorption platform 3 rotate in the same direction, while the grinding wheel 23 is fed downward. The rotation speed of the grinding wheel 23 is greater than that of the adsorption platform 3, so as to grind the wafer.

[0110] A400. When the wafer is ground to the target thickness, stop the rotation of the grinding wheel 23 and the adsorption platform 3, and move the grinding wheel 23 upward to separate it from the wafer.

[0111] A500, removes the adsorption of the wafer and transfers the wafer.

[0112] In this application, the thinning method enables precise wafer thinning. First, the wafer is adsorbed onto the adsorption platform 3 to ensure stable positioning during processing, providing a stable foundation for subsequent processes. Then, the feed assembly drives the grinding wheel 23 downward until it contacts the wafer, achieving precise initiation of the grinding operation. During the grinding stage, the grinding wheel 23 and the adsorption platform 3 rotate in the same direction, with the grinding wheel 23 rotating at a higher speed than the adsorption platform 3. Simultaneously, the grinding wheel 23 continues to feed downward. Through the coordinated control of the speed difference and feed amount, the wafer is ground. When the wafer thickness reaches the target value, the rotation of the grinding wheel 23 and the adsorption platform 3 is immediately stopped, and the feed assembly drives the grinding wheel 23 upward to detach from the wafer, avoiding over-processing. Finally, the adsorption force of the adsorption platform 3 on the wafer is released, and the wafer transfer is completed, forming a closed loop in the entire process.

[0113] The key to the entire process is: First, by positioning the adsorption platform 3 and controlling the feed of the grinding wheel 23, the wafer is ensured to be subjected to uniform force during the thinning process, which effectively improves the flatness and processing accuracy of the wafer; Second, the design of rotation in the same direction and speed difference reduces stress concentration during the grinding process, reduces the risk of wafer damage, and improves product yield; Third, the fully automated operation improves processing efficiency and stability, making it suitable for large-scale production scenarios.

[0114] In one embodiment of this application, in step A300, the rotational speed of the grinding wheel 23 is 4000~6000 rpm, and the rotational speed of the adsorption platform 3 is 200~400 rpm. The rotational speed of the grinding wheel 23 can be, for example, 4000 rpm, 5000 rpm, or 6000 rpm; the rotational speed of the adsorption platform 3 can be, for example, 200 rpm, 300 rpm, or 400 rpm, but is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0115] In this application, the high-speed differential rotation of the grinding wheel 23 and the adsorption platform 3, in conjunction with their co-rotation, ensures that the contact trajectory between the grinding wheel 23 and the wafer surface is continuously spirally distributed, avoiding thickness deviations caused by localized repeated grinding and helping to keep the total thickness deviation of the wafer after thinning stable at a low level. On the other hand, it reduces the reverse impact of the grinding wheel 23 on the wafer surface. Combined with the continuous grinding characteristics of high speed, it can reduce the instantaneous grinding force, reduce lattice distortion and microcrack generation, and help to keep the subsurface damage of the wafer after thinning stable at a low level.

[0116] In one embodiment of this application, in step A300, the downward feed rate is 2~6 μm / s, for example, it can be 2 μm / s, 4 μm / s, or 6 μm / s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0117] In this application, the grinding wheel 23 is fed downwards at a speed of 2~6 μm / s while rotating, which enables uniform grinding layer by layer, effectively controlling the total thickness deviation of the thinned wafer and avoiding local over-grinding or thickness fluctuations caused by excessive feed rate. Furthermore, the relatively low feed rate reduces the amount of grinding per unit time, and combined with co-rotation, it reduces instantaneous grinding stress and impact, decreases lattice defects and microcracks, and helps control the subsurface damage depth at a low level.

[0118] According to another aspect of this application, a grinding wheel is also provided, comprising a substrate 231 and a grinding block 232 disposed on the surface of the substrate 231 and used for grinding a wafer, the grinding block 232 comprising:

[0119] Gel-ceramic composite 2321;

[0120] Abrasive particles 2322 distributed in the gel-ceramic composite 2321;

[0121] The gel ceramic composite 2321 has a staggered helical stacked structure to disperse stress during grinding;

[0122] The raw materials for gel ceramic composite 2321 include calcium carbonate / calcium phosphate composite gel and chitin nanocrystals.

[0123] In this application, the structural diagram of the grinding wheel is as follows: Figure 4 As shown. The substrate 231 provides a good support base for the grinding block 232, which can withstand the grinding force generated by the grinding block 232 during the grinding process, ensure the stability of the grinding block 232 when rotating at high speed, and ensure that the grinding block 232 will not deform due to the force, so that the grinding wheel 23 can continuously and stably perform wafer grinding.

[0124] The internal structure of the grinding block 232 includes a gel-ceramic composite 2321 and abrasive particles 2322 distributed therein. The gel-ceramic composite 2321, which has a staggered spiral stacked structure and is obtained by using calcium carbonate / calcium phosphate composite gel and chitin nanocrystals as raw materials, can effectively disperse the stress generated during grinding, control the subsurface damage depth of the wafer after thinning, ensure the consistency of grinding thickness during wafer thinning, and thus improve the quality of the wafer after thinning.

[0125] In one embodiment of this application, the grinding block 232 further includes pores 2323 distributed in the gel ceramic composite 2321.

[0126] Figure 5 The aperture 2323 shown provides a flow channel for the coolant. During the grinding process, the coolant can flow quickly inside the grinding block 232, promptly removing the heat generated by grinding, reducing the impact of thermal stress on wafer grinding, and ensuring the quality of the thinned wafer. On the other hand, the aperture 2323 allows the grinding debris generated during grinding to be discharged from the grinding area, preventing the grinding debris from accumulating between the grinding block 232 and the wafer, reducing the risk of clogging of the grinding wheel 23, and improving grinding efficiency and the service life of the grinding wheel 23.

[0127] In one embodiment of this application, the staggered spiral stacked structure is arranged parallel to the grinding surface, such as... Figures 5-6 As shown.

[0128] During wafer grinding, the forces acting on the grinding block 232 include shear forces parallel to the grinding surface (generated by the relative motion between the grinding wheel 23 and the wafer) and normal forces perpendicular to the grinding surface. In this application, when the staggered spiral structure of the gel ceramic composite 2321 is arranged parallel to the grinding surface, the "layer direction" of its stacking is consistent with the direction of the shear force, which can prevent the gel ceramic composite 2321 from exhibiting "interlayer peeling" or breakage. The normal force is perpendicular to the stacked layer structure, which not only makes the force between the grinding block 232 and the wafer average, avoiding deformation and damage caused by stress concentration, but also makes the wear of the stacked structure consistent, thereby maintaining a stable stress average state, improving the structural stability of the grinding block 232 under high-speed, high-load grinding, and preventing the abrasive grains 2322 from falling off or the gel ceramic composite 2321 from cracking.

[0129] In one embodiment of this application, the surface of the abrasive grain 2322 is covered with carboxyl functional groups, which are chemically bonded to calcium ions in the gel ceramic composite 2321.

[0130] In this application, the active Ca in the calcium carbonate / calcium phosphate composite gel 2+ By bonding with the carboxyl functional groups on the surface of abrasive grain 2322 through strong chemical bonds, not only are the mechanical properties of grinding wheel 23 improved, but the abrasive grain 2322 is also less likely to fall off during the wafer thinning process. Ultimately, this achieves the effect of improving the service life of wafer thinning equipment and reducing the total thickness deviation and subsurface damage depth of the wafer after thinning.

[0131] It is evident that the grinding wheel 23 of this application can effectively suppress excessive stress concentration during the wafer grinding process. Thus, while reducing the total thickness deviation and subsurface damage depth of the wafer after thinning, it avoids the degradation of chip electrical performance caused by grinding damage and extends the service life of the grinding wheel 23.

[0132] In one embodiment of this application, a plurality of grinding blocks 232 are provided on the surface of the substrate 231, and the plurality of grinding blocks 232 are distributed at intervals along the circumferential direction of the substrate 231.

[0133] In this application, the multiple grinding blocks 232 spaced apart circumferentially along the substrate 231 form a chip removal channel. When the grinding wheel 23 rotates at high speed, the spaced areas can quickly guide the grinding debris, preventing debris from accumulating between the grinding blocks 232 and the wafer, thus avoiding secondary scratches or localized compression damage to the wafer. This helps maintain the stability of the subsurface damage depth of the wafer after thinning. At the same time, the spaced areas increase airflow, accelerate the dissipation of grinding heat, reduce wafer thermal deformation caused by localized overheating, and ensure precise control of the total thickness deviation of the wafer after thinning.

[0134] In one embodiment of this application, an annular groove is provided on the surface of the substrate 231, and one end of the grinding block 232 is embedded in the annular groove.

[0135] In this application, an annular groove is provided on the surface of the substrate 231 to provide radial and axial dual constraints for the grinding block 232. This effectively avoids displacement or vibration of the grinding block 232 due to centrifugal force during high-speed rotation, ensuring the consistency of the grinding trajectory of the grinding wheel 23 and helping to reduce the overall thickness deviation of the wafer after thinning. In addition, embedding one end of the grinding block 232 into the annular groove allows for a tighter bond between the grinding block 232 and the substrate 231, reducing stress loss during the grinding process, ensuring that the grinding force is applied evenly to the wafer surface, reducing the risk of local over-grinding, and preventing scratches on the wafer surface due to loosening of the grinding block 232, thus helping to reduce subsurface damage to the wafer after thinning.

[0136] In this application, the shape of the grinding block 232 can be a rounded rectangle or a fan shape. The reason is that when the shape of the grinding block 232 is a rounded rectangle, the local stress concentration during grinding can be reduced by the rounded corners, thus avoiding scratches or chipping on the wafer surface. When the shape of the grinding block 232 is a fan shape, the contact between the abrasive grains and the wafer can be gradually transitioned by the arc edge, thus reducing the impact on the wafer.

[0137] According to another aspect of this application, this application also proposes a method for preparing the above-mentioned grinding wheel, comprising the following steps:

[0138] B100. After mixing the abrasive and the pore-forming agent evenly, a mixture is obtained.

[0139] B200, after uniformly mixing calcium carbonate / calcium phosphate composite gel and chitin nanocrystals, a gel ceramic binder is obtained;

[0140] B300. Add the gel ceramic binder to the mixture and mix evenly. Transfer the mixture to a mold, press and shape it, and vacuum dry to obtain grinding block 232.

[0141] B400. The grinding block 232 is placed on the surface of the substrate 231 to obtain the grinding wheel 23.

[0142] In this application, the dry materials (abrasive and pore-forming agent) are mixed separately with the gel ceramic binder, which further improves the mechanical properties of the grinding wheel 23 and further reduces the total thickness deviation and subsurface damage depth of the wafer after thinning. Pre-mixing the abrasive and pore-forming agent ensures consistent distribution of the pore-forming agent within the system, laying the foundation for the subsequent formation of a uniform pore structure and improving the chip removal performance and heat dissipation efficiency of the grinding block 232. Simultaneously, pre-mixing the calcium carbonate / calcium phosphate composite gel with chitin nanocrystals facilitates sufficient contact between the two, thereby better forming an organic-inorganic interpenetrating network. Finally, mixing the gel ceramic binder with the abrasive / pore-forming agent mixture ensures stable bonding of the abrasive particles, guaranteeing the overall structural strength and service life of the grinding block 232, further contributing to improved wafer thinning equipment lifespan and reduced total wafer thickness deviation and subsurface damage depth after thinning. In addition, the introduction of gel ceramic binder allows the curing process to be carried out at room temperature, which reduces production energy consumption compared with the traditional high-temperature melting process. At the same time, it avoids the problem of diamond graphitization caused by high temperature sintering, which leads to a decrease in hardness and wear resistance and affects the grinding performance of grinding wheel 23.

[0143] In one embodiment of this application, during compression molding, the pressure is 10~70 MPa, for example, it can be 10 MPa, 15 MPa, 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 50 MPa, 60 MPa or 70 MPa, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0144] In this application, the pressure during compression molding is controlled at 10~70 MPa, which allows the abrasive, gel ceramic binder, and pore-forming agent to come closer together through mechanical extrusion, forming initial contact and interlocking, thus preventing the green body from becoming loose and shedding powder. At the same time, it prevents the pore-forming agent from being crushed, thus avoiding damage to the pre-designed pore structure and affecting heat dissipation, chip holding capacity, and chip removal capabilities.

[0145] The present application will be described in detail below with reference to examples. The embodiments described below according to the present application can be modified in various forms, therefore the scope of the present application should not be construed as limited to the embodiments described in detail below. Examples are provided to help those skilled in the art to more easily understand the present application.

[0146] Unless otherwise specified, all parts in the following examples and comparative examples are by weight. The average particle size of the diamond micropowder is 1.0 μm, and the particle size of the Al2O3 hollow microspheres is 15 μm. The preparation method of the diamond micropowder with carboxyl functional groups on the surface is as follows: the diamond micropowder is soaked in concentrated nitric acid, filtered to remove the concentrated nitric acid, washed three times with deionized water and ethanol respectively, and then dried in an oven for 24 h to obtain the diamond micropowder with carboxyl functional groups on the surface.

[0147] Example 1

[0148] like Figure 1 and Figure 2 The wafer thinning equipment shown includes a substrate 1, on which a rotating disk 4 is mounted. Above the rotating disk 4 are multiple adsorption platforms 3 spaced apart along the circumference. The rotating disk 4 can rotate around its central axis to change the position of the adsorption platforms 3, so that the wafers supported by the adsorption platforms 3 can switch between rough grinding station, fine grinding station and loading / unloading station.

[0149] The end of the equipment base 1 is equipped with an upright support, and two grinding devices 2 are arranged on the side of the support. One is a rough grinding part and the other is a fine grinding part. The two have similar structures and are equipped with a feed assembly (not shown) that drives the grinding wheel 23 to move up and down and a mechanism that drives the grinding wheel to rotate along the rotating shaft 22. The feed assembly includes a lifting motor (not shown), which is slidably connected to the housing of the rotating shaft through a lead screw. The housing is slidably connected to the side of the column so that the rotation of the lifting motor realizes the vertical movement of the rotating shaft 22, thereby changing the position of the grinding wheel 23 relative to the adsorption platform 3.

[0150] The adsorption platform 3 supports the wafer and drives its rotation. The grinding device 2 is vertically positioned above the adsorption platform 3. The lower part of the grinding device 2 has a grinding wheel 23 capable of circumferential rotation to grind the wafer. The grinding wheel 23 includes a gel-ceramic composite 2321 with a staggered spiral stacked structure to disperse stress during grinding. The raw material of the gel-ceramic composite 2321 is a ceramic gel binder, which includes calcium carbonate / calcium phosphate composite gel and chitin nanocrystals. The staggered spiral stacked structure is arranged parallel to the grinding surface.

[0151] The grinding apparatus 2 includes a feed assembly, a rotary shaft 22, and a grinding wheel 23. The grinding block 232 in the grinding wheel 23 is used to grind the wafer. The grinding wheel 23 may be a cup-shaped grinding wheel, mounted at the lower end of the rotary shaft 22. The rotary shaft 22 is used to rotate the grinding wheel 23 about its axis of rotation. The feed assembly can drive the rotary shaft 22 and the grinding wheel 23 to move up and down synchronously. When the wafer needs grinding, the grinding wheel 23 moves down to its bottom surface and contacts the wafer under the drive of the feed assembly. At this time, both the grinding wheel 23 and the wafer are rotating in the same direction but at different speeds, and the grinding wheel 23 is used to grind the wafer. The feed assembly has a known structure and includes, for example, multiple linear guides that guide the movement direction of the rotary shaft 22 and a ball screw-slider mechanism that moves the rotary shaft 22 up and down.

[0152] The grinding wheel 23 includes a plurality of grinding blocks 232, which may be rounded rectangles or fan-shaped, and at least a portion of these grinding blocks 232 are embedded in an annular groove and spaced apart from each other on the substrate 231. The substrate 231 can be fastened to the lower end of the rotating shaft 22 by bolts.

[0153] The adsorption platform 3 has a chuck spindle 31, a worktable 32, and an adsorption disk 33. The chuck spindle 31 moves along the axis of rotation. The adsorption disk 33, made of a porous material such as alumina, is embedded in the upper surface of the worktable 32. The adsorption platform 3 has a conduit that penetrates its interior and extends to its surface. The conduit is connected to a vacuum source, a compressed air source, or a water supply source via a rotary joint. When the vacuum source is activated, the wafer placed on the adsorption platform 3 is adsorbed by the adsorption disk 33. Conversely, when the compressed air source or water supply source is activated, the adsorption between the wafer and the adsorption disk 33 is released. The adsorption platform 3 may be equipped with a tilting device that tilts relative to the grinding wheel 23, or the grinding device 2 may be equipped with a tilting structure that tilts the rotation axis 22. This allows adjustment of the contact between the grinding block 232 and the wafer to grind the wafer into the desired shape.

[0154] The operation of the grinding device 2 is controlled by a control device. The control device controls each component of the grinding device 2. The control device includes, for example, a CPU and a memory. Furthermore, the function of the control device can be implemented through software control or through hardware operation. For example, the control device can control the movement of the feed assembly, the rotary axis 22, and the chuck spindle 31 according to preset grinding process parameters, such as feed rate and rotational speed, to achieve an automated grinding process. Simultaneously, the control device also has fault diagnosis and alarm functions, capable of monitoring the operating status of each part of the equipment in real time, issuing alarms promptly and taking corresponding protective measures when abnormalities occur, ensuring the safety of the equipment and operators.

[0155] Example 2

[0156] The wafer thinning method, using the wafer thinning equipment of Example 1, includes the following steps:

[0157] A100, The wafer is adsorbed and fixed on the adsorption platform 3.

[0158] A110. Preparation: Before performing wafer thinning operation, ensure that the surface of the adsorption platform 3 is clean and free of impurities to avoid impurities affecting the adsorption effect and grinding quality of the wafer. You can use a lint-free cloth dipped in an appropriate amount of alcohol to wipe and clean the surface of the adsorption platform 3.

[0159] A120. Place the wafer: Using a vacuum pen or other precision gripping tool, place the wafer to be thinned on the adsorption platform 3, ensuring that the center of the wafer is aligned with the center of the adsorption platform 3.

[0160] A130. Initiating Vacuum Adsorption: The vacuum source connected to the adsorption platform 3 is activated via the control device. The porous structure inside the adsorption platform 3 creates a negative pressure under vacuum, adsorbing the wafer onto its surface. To ensure strong adsorption, the vacuum level of the adsorption platform 3 can be monitored in real time via the control device. When the vacuum level reaches the preset value, it indicates that the wafer has been stably adsorbed and the next step can be performed.

[0161] A200, driving the grinding wheel 23 down to contact the wafer.

[0162] Parameter setting: Input the target position parameter of the grinding wheel 23 into the control device. This parameter is determined based on factors such as the thickness of the wafer, the grinding allowance, and the initial position of the grinding wheel 23.

[0163] Start the feed assembly: The control device sends a command to the feed assembly, precisely controlling its movement direction to ensure it moves vertically downwards. The feed assembly drives the grinding wheel 23 to move smoothly downwards at a set speed. During the movement, the control device monitors the position information of the feed assembly in real time and compares it with the preset target position. When it approaches the target position, the feed speed is reduced to achieve precise alignment.

[0164] A300, the grinding wheel 23 and the adsorption platform 3 rotate in the same direction, while the grinding wheel 23 is fed downward. The rotation speed of the grinding wheel 23 is greater than the rotation speed of the adsorption platform 3, so as to grind the wafer.

[0165] A310, Rotary Start: The control device simultaneously starts the grinding wheel 23 and the adsorption platform 3. The grinding wheel 23 rotates at a high speed at a set speed, while the adsorption platform 3 and the wafers adsorbed on it rotate in the same direction at a relatively low speed.

[0166] A320. Grinding: After the grinding wheel 23 and the adsorption platform 3 reach a stable rotation state, the control device continues to control the feed assembly, causing the grinding wheel 23 to feed onto the wafer. During the feeding process, a pressure sensor installed on the grinding wheel 23 monitors the contact pressure between the grinding wheel 23 and the wafer in real time and feeds it back to the control device. When the pressure reaches a preset value, such as 5 N, the control device stops the feeding action of the feed assembly to ensure that the grinding wheel 23 and the wafer maintain a suitable grinding pressure, which ensures the grinding effect while avoiding excessive pressure that could damage the wafer. After the grinding wheel 23 and the wafer are adjusted to a suitable grinding pressure, the grinding wheel 23 and the adsorption platform 3 continue to rotate, and the grinding block 232 of the grinding wheel 23 grinds the surface of the wafer.

[0167] Grinding Parameter Monitoring and Adjustment: During the grinding process, the control device monitors several key parameters in real time, such as the rotational speed of the grinding wheel 23, the rotational speed of the adsorption platform 3, the grinding pressure, and the grinding time. These parameter information is collected in real time by sensors installed in key parts of the wafer thinning equipment, such as speed sensors, pressure sensors, and thickness sensors, and fed back to the control device. The control device dynamically adjusts the grinding process based on the preset grinding process model and the actual collected parameter data.

[0168] A400. When the wafer is ground to the target thickness, stop the rotation of the grinding wheel 23 and the adsorption platform 3, and move the grinding wheel 23 upward to separate it from the wafer.

[0169] A410. Thickness Detection and Judgment: A non-contact thickness sensor installed near the grinding wheel 23 continuously monitors the thickness changes of the wafer and feeds back the real-time thickness data to the control device. When the control device receives thickness data showing that the wafer has been ground to the target thickness, it determines that the grinding is complete.

[0170] A420. Stopping Rotation and Separating the Grinding Wheel: The control device immediately issues a command to stop the rotation of the grinding wheel 23 and the adsorption platform 3. Subsequently, the control device activates the feed assembly to move the grinding wheel 23 upward at a set speed, so that the grinding wheel 23 is quickly separated from the wafer, avoiding unnecessary damage caused by prolonged contact between the grinding wheel 23 and the wafer surface after it stops rotating.

[0171] A500, removes the adsorption of the wafer and transfers the wafer.

[0172] A510. Gas Source Switching: The control device shuts off the vacuum source and switches to either a compressed air source or a water source, depending on the actual process. Compressed air or water enters the adsorption platform 3, disrupting the negative pressure between the adsorption platform 3 and the wafer, thereby releasing the adsorption force.

[0173] A520. Wafer Removal: Using a vacuum pen or other precision gripping tools, the thinned wafer is removed from the adsorption platform 3, completing the entire wafer thinning process.

[0174] Example 3

[0175] The method for preparing a grinding wheel includes the following steps:

[0176] B000, a calcium carbonate / calcium phosphate composite gel, was prepared by the following method:

[0177] Dissolve 0.5 g of calcium chloride dihydrate in 100 mL of anhydrous ethanol, add 10 mL of triethylamine, stir for 30 min, then pass carbon dioxide gas for 15 min. The solution gradually changes from colorless and transparent to milky white, and then quickly turns to light blue. At this point, calcium carbonate gel is obtained.

[0178] Dissolve 0.5 g of calcium chloride dihydrate in 80 mL of anhydrous ethanol, add 10 mL of triethylamine, and stir for 30 min to obtain a mixture for later use. Then, measure 0.15 mL of concentrated phosphoric acid with a concentration of 1.685 g / mL and dissolve it in 20 mL of anhydrous ethanol, and stir for 30 min to obtain an ethanol solution of phosphoric acid. Then, add the ethanol solution of phosphoric acid dropwise to the mixture and stir for 2 h to obtain calcium phosphate gel.

[0179] The calcium carbonate gel and calcium phosphate gel were uniformly mixed, and then washed three times with anhydrous ethanol at 8000 rpm to obtain a calcium carbonate / calcium phosphate composite gel. SEM images are shown below. Figure 7 As shown in the figure, no staggered spiral structure appears.

[0180] Chitin nanocrystals were prepared by the following method:

[0181] 5 g of chitin powder was added to 20 mL of 0.5 M citric acid solution. The mixture was stirred at room temperature for 30 min, then reacted in a 50 °C water bath for 12 h. After cooling to 4 °C, the mixture was neutralized with pH 7.0 phosphate-buffered saline (PBS) and dialyzed for 48 h (changing the water every 6 h) to remove residual acid and salt. After centrifugation for 20 min, the precipitate was removed, and the supernatant was retained to obtain chitin nanocrystals. SEM images are shown below. Figure 8 As shown;

[0182] B100. Mix 50 parts of diamond micro powder and 10 parts of Al2O3 hollow microsphere pore-forming agent evenly to obtain a mixture;

[0183] B200: Mix 25 parts of calcium carbonate / calcium phosphate composite gel and 15 parts of chitin nanocrystals evenly to obtain a gel ceramic binder;

[0184] B300. The gel ceramic binder is added to the mixture and stirred for 1 hour. The mixture is then transferred to a mold, stirred thoroughly, and leveled. The mold is then pressed using a hydraulic press to obtain a green body, with a pressure of 70 MPa and a holding time of 5 minutes. The green body is placed in a vacuum oven and dried at room temperature under vacuum for 48 hours to obtain a grinding block. The SEM image of the gel ceramic binder in the grinding block is shown below. Figure 9 As shown in the figure, the gel ceramic binder has a staggered helical structure.

[0185] B400: The grinding block is assembled onto an aluminum substrate by bonding multiple pieces, and the end face and outer circle are trimmed and sharpened, and then dynamically balanced to obtain the grinding wheel.

[0186] Example 4

[0187] The method for preparing a grinding wheel includes the following steps:

[0188] B000, a calcium carbonate / calcium phosphate composite gel, was prepared by the following method:

[0189] Dissolve 0.5 g of calcium chloride dihydrate in 100 mL of anhydrous ethanol, add 10 mL of triethylamine, stir for 30 min, then pass carbon dioxide gas for 15 min. The solution gradually changes from colorless and transparent to milky white, and then quickly turns to light blue. At this point, calcium carbonate gel is obtained.

[0190] Dissolve 0.5 g of calcium chloride dihydrate in 80 mL of anhydrous ethanol, add 10 mL of triethylamine, and stir for 30 min to obtain a mixture for later use. Then, measure 0.15 mL of concentrated phosphoric acid with a concentration of 1.685 g / mL and dissolve it in 20 mL of anhydrous ethanol, and stir for 30 min to obtain an ethanol solution of phosphoric acid. Then, add the ethanol solution of phosphoric acid dropwise to the mixture and stir for 2 h to obtain calcium phosphate gel.

[0191] The calcium carbonate gel and calcium phosphate gel were mixed evenly, and then washed three times with anhydrous ethanol at 8000 rpm to obtain calcium carbonate / calcium phosphate composite gel.

[0192] Chitin nanocrystals were prepared by the following method:

[0193] 5 g of chitin powder was added to 20 mL of 0.5 M citric acid solution. After stirring at room temperature for 30 min, the mixture was stirred in a 50 °C water bath for 12 h. After cooling to 4 °C, the mixture was neutralized with phosphate buffered saline (PBS) at pH 7.0 and dialyzed for 48 h (with water changed every 6 h) to remove residual acid and salt. After centrifugation for 20 min, the precipitate was removed, and the supernatant was retained to obtain chitin nanocrystals.

[0194] B100. Mix 70 parts of diamond micro powder and 10 parts of Al2O3 hollow microsphere pore-forming agent evenly to obtain a mixture;

[0195] B200, after mixing 12.5 parts of calcium carbonate / calcium phosphate composite gel and 7.5 parts of chitin nanocrystals evenly, a gel ceramic binder is obtained;

[0196] B300. Add the gel ceramic binder to the mixture and stir for 1 hour. Transfer it to a mold, stir evenly, and scrape it flat. Press it into a blank using a hydraulic press with a pressure of 30 MPa and a holding time of 5 minutes. Place the blank in a vacuum oven and dry it in a vacuum environment at room temperature for 48 hours to obtain a grinding block.

[0197] B400: The grinding block is assembled onto an aluminum substrate by bonding multiple pieces, and the end face and outer circle are trimmed and sharpened, and then dynamically balanced to obtain the grinding wheel.

[0198] Example 5

[0199] The only difference from Example 3 is that the diamond micro powder is replaced with an equal amount of diamond micro powder with carboxyl functional groups on the surface.

[0200] Example 6

[0201] The only difference from Example 4 is that the diamond powder is replaced with an equal amount of diamond powder with carboxyl functional groups on the surface.

[0202] Example 7

[0203] The only difference from Example 5 is that: 20 parts of calcium carbonate / calcium phosphate composite gel and 20 parts of chitin nanocrystals.

[0204] Example 8

[0205] The only difference from Example 5 is that: 15 parts of calcium carbonate / calcium phosphate composite gel and 25 parts of chitin nanocrystals.

[0206] Example 9

[0207] The only difference from Example 5 is the method for preparing the grinding wheel, which includes the following steps:

[0208] B000, a calcium carbonate / calcium phosphate composite gel, was prepared by the following method:

[0209] Dissolve 0.5 g of calcium chloride dihydrate in 100 mL of anhydrous ethanol, add 10 mL of triethylamine, stir for 30 min, then pass carbon dioxide gas for 15 min. The solution gradually changes from colorless and transparent to milky white, and then quickly turns to light blue. At this point, calcium carbonate gel is obtained.

[0210] Dissolve 0.5 g of calcium chloride dihydrate in 80 mL of anhydrous ethanol, add 10 mL of triethylamine, and stir for 30 min to obtain a mixture for later use. Then, measure 0.15 mL of concentrated phosphoric acid with a concentration of 1.685 g / mL and dissolve it in 20 mL of anhydrous ethanol, and stir for 30 min to obtain an ethanol solution of phosphoric acid. Then, add the ethanol solution of phosphoric acid dropwise to the mixture and stir for 2 h to obtain calcium phosphate gel.

[0211] The calcium carbonate gel and calcium phosphate gel were mixed evenly, and then washed three times with anhydrous ethanol at 8000 rpm to obtain calcium carbonate / calcium phosphate composite gel.

[0212] Chitin nanocrystals were prepared by the following method:

[0213] 5 g of chitin powder was added to 20 mL of 0.5 M citric acid solution. After stirring at room temperature for 30 min, the mixture was stirred in a 50 °C water bath for 12 h. After cooling to 4 °C, the mixture was neutralized with phosphate buffered saline (PBS) at pH 7.0 and dialyzed for 48 h (with water changed every 6 h) to remove residual acid and salt. After centrifugation for 20 min, the precipitate was removed, and the supernatant was retained to obtain chitin nanocrystals.

[0214] B100. Mix 50 parts of diamond micro powder with carboxyl functional groups on the surface, 10 parts of Al2O3 hollow microsphere pore-forming agent, 20 parts of calcium carbonate / calcium phosphate composite gel, and 20 parts of chitin nanocrystals evenly, transfer to a mold, stir evenly, scrape flat, and press into a blank by a hydraulic press, wherein the pressure is 70 MPa and the holding time is 5 min. Place the blank in a vacuum oven and dry it in a vacuum room temperature environment for 48 h to obtain a grinding block.

[0215] B200: The grinding block is assembled onto an aluminum substrate by bonding multiple pieces, and the end face and outer circle are trimmed and sharpened, and then dynamically balanced to obtain the grinding wheel.

[0216] Comparative Example 1

[0217] The only difference from Example 3 is the method of preparing the grinding wheel, which includes the following steps:

[0218] B000, a calcium carbonate / calcium phosphate composite gel, was prepared by the following method:

[0219] Dissolve 0.5 g of calcium chloride dihydrate in 100 mL of anhydrous ethanol, add 10 mL of triethylamine, stir for 30 min, then pass carbon dioxide gas for 15 min. The solution gradually changes from colorless and transparent to milky white, and then quickly turns to light blue. At this point, calcium carbonate gel is obtained.

[0220] Dissolve 0.5 g of calcium chloride dihydrate in 80 mL of anhydrous ethanol, add 10 mL of triethylamine, and stir for 30 min to obtain a mixture for later use. Then, measure 0.15 mL of concentrated phosphoric acid with a concentration of 1.685 g / mL and dissolve it in 20 mL of anhydrous ethanol, and stir for 30 min to obtain an ethanol solution of phosphoric acid. Then, add the ethanol solution of phosphoric acid dropwise to the mixture and stir for 2 h to obtain calcium phosphate gel.

[0221] The calcium carbonate gel and calcium phosphate gel were mixed evenly, and then washed three times with anhydrous ethanol at 8000 rpm to obtain calcium carbonate / calcium phosphate composite gel.

[0222] B100. Mix 50 parts of diamond micro powder and 10 parts of Al2O3 hollow microsphere pore-forming agent evenly to obtain a mixture;

[0223] B200. Add 40 parts of calcium carbonate / calcium phosphate composite gel to the mixture and stir for 1 hour. Transfer to a mold, stir evenly and scrape flat. Press and form a blank by a hydraulic press with a pressure of 70 MPa and a holding time of 5 minutes. Place the blank in a vacuum oven and dry it in a vacuum room temperature environment for 48 hours to obtain a grinding block.

[0224] B300: The grinding block is assembled onto an aluminum substrate by bonding multiple pieces, and the end face and outer circle are trimmed and sharpened, and then dynamically balanced to obtain the grinding wheel.

[0225] Comparative Example 2

[0226] The only difference from Example 5 is the method for preparing the grinding wheel, which includes the following steps:

[0227] B000, a calcium carbonate / calcium phosphate composite gel, was prepared by the following method:

[0228] Dissolve 0.5 g of calcium chloride dihydrate in 100 mL of anhydrous ethanol, add 10 mL of triethylamine, stir for 30 min, then pass carbon dioxide gas for 15 min. The solution gradually changes from colorless and transparent to milky white, and then quickly turns to light blue. At this point, calcium carbonate gel is obtained.

[0229] Dissolve 0.5 g of calcium chloride dihydrate in 80 mL of anhydrous ethanol, add 10 mL of triethylamine, and stir for 30 min to obtain a mixture for later use. Then, measure 0.15 mL of concentrated phosphoric acid with a concentration of 1.685 g / mL and dissolve it in 20 mL of anhydrous ethanol, and stir for 30 min to obtain an ethanol solution of phosphoric acid. Then, add the ethanol solution of phosphoric acid dropwise to the mixture and stir for 2 h to obtain calcium phosphate gel.

[0230] The calcium carbonate gel and calcium phosphate gel were mixed evenly, and then washed three times with anhydrous ethanol at 8000 rpm to obtain calcium carbonate / calcium phosphate composite gel.

[0231] B100. Mix 50 parts of diamond micro powder with carboxyl functional groups on the surface and 10 parts of Al2O3 hollow microsphere pore-forming agent evenly to obtain a mixture.

[0232] B200. Add 40 parts of calcium carbonate / calcium phosphate composite gel to the mixture and stir for 1 hour. Transfer to a mold, stir evenly and scrape flat. Press and form a blank by a hydraulic press with a pressure of 70 MPa and a holding time of 5 minutes. Place the blank in a vacuum oven and dry it in a vacuum room temperature environment for 48 hours to obtain a grinding block.

[0233] B300: The grinding block is assembled onto an aluminum substrate by bonding multiple pieces, and the end face and outer circle are trimmed and sharpened, and then dynamically balanced to obtain the grinding wheel.

[0234] Comparative Example 3

[0235] The only difference from Example 5 is that the gel ceramic binder is replaced with an equal amount of commercially available ceramic binder of type 88877.

[0236] Comparative Example 4

[0237] Purchase 6000# grinding wheels from outside.

[0238] Experimental Example 1: Mechanical Property Testing

[0239] The following performance tests were performed on the grinding blocks from Examples 3-9 and Comparative Examples 1-3:

[0240] (1) Flexural strength: Prepare a sample strip with a length × width × height of 65 mm × 7 mm × 7 mm, and measure the flexural strength on a single lever flexural strength tester with a load speed of 10 N / S;

[0241] (2) Compressive strength: Prepare a cylindrical sample block with a diameter of Φ20 mm×20 mm, and measure the compressive strength on a compressive strength testing machine with a support blade diameter of 10 mm and a load speed of 200 N / S;

[0242] (3) Tensile strength: Prepare an “8” shaped sample block, clamp the sample block on a tensile testing machine, and apply a tensile force at a constant rate of 400 N / s until the sample block breaks.

[0243] The test results are shown in Table 1 below.

[0244] Table 1. Mechanical property test results

[0245]

[0246] As shown in Table 1, the flexural strength, tensile strength, and compressive strength of the grinding blocks obtained in Examples 3-9 are higher than those in Comparative Examples 1-3. This indicates that by using calcium carbonate / calcium phosphate composite gel and chitin nanocrystals as gel ceramic binders, and constructing a staggered helical structure template through the self-assembly of chitin nanocrystals into a gel ceramic binder, the biomimetic mineralization process of the calcium carbonate / calcium phosphate bicomponent co-crosslinked with inorganic ions can be regulated, and an organic-inorganic interpenetrating network can be constructed at the molecular level, which can improve the mechanical properties of the grinding blocks, thereby improving the mechanical properties of the grinding wheels.

[0247] The abrasive block obtained in Example 5 exhibited higher flexural strength, tensile strength, and compressive strength than that obtained in Example 3. Similarly, the abrasive block obtained in Example 6 showed higher flexural strength, tensile strength, and compressive strength than that obtained in Example 4. This indicates that the carboxyl functional groups on the surface of the abrasive after acid treatment interact with the active Ca in the gel ceramic binder. 2+ The formation of a strong chemical bond network can further improve the mechanical properties of the grinding block, thereby further improving the mechanical properties of the grinding wheel.

[0248] Experiment Example 2: Grinding Performance Test

[0249] The grinding wheels prepared in Examples 3-9 and Comparative Examples 1-4 were used to grind 12-inch wafers. The total thickness deviation, subsurface damage depth, and grinding wheel life were measured after thinning. The specific test method was as follows: The wafer was adsorbed onto the adsorption platform; a grinding wheel with an outer diameter of 300 mm × an inner diameter of 237 mm × a height of 32 mm was moved down to contact the wafer under the drive of the feed assembly; the grinding wheel and the adsorption platform rotated in the same direction, with the grinding wheel rotating at 4800 rpm and the adsorption platform rotating at 300 rpm; during rough grinding, the grinding wheel was fed downwards at a feed rate of 5 / 4 / 3 μm / s while rotating, and the cooling water flow rate was 4 L / min during the grinding process; after rough grinding, the grinding wheel prepared in this grinding block was used for fine grinding, with the grinding wheel being fed downwards at a feed rate of 0.3 / 0.2 / 0.1 μm / s while rotating, and the cooling water flow rate was 4 L / min during the grinding process, until the wafer removal amount was 765. μm, the grinding wheel and adsorption platform stop rotating, the feed assembly drives the grinding wheel to move upward until it separates from the wafer; the adsorption platform releases the wafer from the wafer, and the wafer is transferred for testing.

[0250] The test results are shown in Table 2 below.

[0251] Table 2 Grinding performance test results

[0252]

[0253] As shown in Table 2, the total thickness deviation of the wafers after thinning by the grinding wheels obtained in Examples 3-9 is lower than that in Comparative Examples 1-4. This indicates that the grinding wheels using gel ceramic binders have superior grinding stability, enabling more uniform material removal, suppressing local overcutting or residue, and thus reducing the total thickness deviation of the wafers after thinning. Simultaneously, the subsurface damage depth of the wafers after thinning by the grinding wheels obtained in Examples 3-9 is lower than that in Comparative Examples 1-4. This indicates that the grinding wheels using gel ceramic binders provide a finer, more buffered grinding behavior, thereby reducing microscopic damage to the wafer structure and achieving the effect of reducing the subsurface damage depth of the wafers after thinning. Furthermore, the service life of the grinding wheels obtained in Examples 3-9 is higher than that in Comparative Examples 1-4, indicating that the grinding wheels using gel ceramic binders have a lower wear rate, stronger abrasive grain retention ability, and stronger binder stability, thus improving the service life of the wafer thinning equipment.

[0254] The grinding wheel obtained in Example 5, after thinning the wafer, exhibited lower total thickness deviation and subsurface damage depth compared to Example 3, while its service life was longer. Similarly, the grinding wheel obtained in Example 6, after thinning the wafer, showed lower total thickness deviation and subsurface damage depth compared to Example 4, while its service life was longer. This indicates that the abrasive, after acid treatment, possesses carboxyl functional groups on its surface, which interact with the active Ca in the gel ceramic binder. 2+ The formation of a strong chemical bonding network has achieved the effects of further reducing the total thickness deviation of the wafer after thinning, the subsurface damage depth, and further improving the service life of the wafer thinning equipment.

[0255] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A wafer thinning equipment, characterized in that, It includes a grinding device and an adsorption platform, wherein the adsorption platform is used to support the wafer and drive the wafer to rotate; The grinding device is raised and lowered above the adsorption platform, and the lower part of the grinding device has a grinding wheel for grinding wafers; The grinding wheel includes a base material and a plurality of grinding blocks, the grinding blocks being fixed to the base material by an adhesive layer; The grinding block includes a gel ceramic composite having a staggered spiral stacked structure for dispersing stress during grinding, wherein the staggered spiral stacked structure is arranged parallel to the grinding surface; The raw material of the gel-ceramic composite is a ceramic gel binder, which includes calcium carbonate / calcium phosphate composite gel and chitin nanocrystals in a mass ratio of 3:5 to 5:

3. The molar ratio of calcium ions in the calcium carbonate gel to calcium ions in the calcium phosphate gel in the calcium carbonate / calcium phosphate composite gel is 1:0.5~1.

2. The wafer thinning equipment according to claim 1, characterized in that, The raw materials for the grinding block include abrasive, ceramic gel binder, and pore-forming agent.

3. The wafer thinning equipment according to claim 2, characterized in that, The surface of the abrasive has carboxyl functional groups, which are chemically bonded to calcium ions in the gel ceramic composite.

4. The wafer thinning equipment according to claim 2, characterized in that, The abrasive has an average particle size of 0.5~1.0μm.

5. The wafer thinning equipment according to claim 2, characterized in that, The mass ratio of the abrasive, the gel ceramic binder, and the pore-forming agent is 50~70:20~40:

10.

6. The wafer thinning apparatus according to any one of claims 1 to 5, characterized in that, The grinding apparatus includes: The feeding assembly is vertically connected above the adsorption platform; A rotating shaft, driven by the feed assembly for lifting, is connected to the lower end of the rotating shaft.

7. The wafer thinning apparatus according to any one of claims 1 to 5, characterized in that, The adsorption platform includes: The worktable has a chuck spindle at the bottom, which drives the worktable to rotate. An adsorption disk, disposed on the worktable, is used to adsorb wafers. The adsorption disk can drive the wafers to rotate synchronously under the action of the worktable.

8. A thinning method, characterized in that, The wafer is thinned using the wafer thinning apparatus according to any one of claims 1 to 7.

9. The thinning method according to claim 8, characterized in that, Includes the following steps: A100. Adsorb and fix the wafer onto the adsorption platform; A200, drives the grinding wheel down to contact the wafer; A300: The grinding wheel and the adsorption platform rotate in the same direction, while the grinding wheel is fed downwards. The rotational speed of the grinding wheel is greater than that of the adsorption platform to grind the wafer. A400: When the wafer is ground to the target thickness, stop the rotation of the grinding wheel and the adsorption platform, and move the grinding wheel upward to separate it from the wafer; A500, removes the adsorption of the wafer and transfers the wafer.

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