A pre-cut layer for multi-wire sawing of semiconductor silicon ingot slurry, a preparation method and application thereof

Abstract

The application provides a pre-cut layer for semiconductor silicon ingot slurry multi-wire cutting, a preparation method and application thereof. The pre-cut layer is an epoxy resin-based composite material, and comprises the following components in percentage by mass: 30-40% of an epoxy resin matrix, 3-7% of a toughening agent, 12-16% of a curing agent, 0.5-1.5% of an accelerator, and 40-50% of inorganic hard fillers. The pre-cut layer is pasted on the entry port end face of the semiconductor silicon ingot to be cut, and the pre-cut layer and the semiconductor silicon ingot are cut by using a slurry multi-wire cutting process. In the pre-cut layer stage, low-speed slow feeding is adopted to realize rough grinding of the slurry and in-situ slow release of fine SiC, so that the slurry particle size is quickly stabilized. After entering the silicon ingot cutting stage, high-speed fast feeding is switched to ensure the cutting efficiency. The slurry cutting force is uniform and stable throughout the process, the taper problem of thin entry port and thick exit port is eliminated from the root, and the silicon wafer cutting quality and yield are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor material processing technology, and in particular to a pre-cutting layer for multi-wire cutting of semiconductor silicon ingots, its preparation method, and its application. Background Technology

[0002] In the semiconductor silicon ingot processing, slurry multi-wire cutting is the core process for cutting silicon ingots into silicon wafers. This process typically uses multiple high-speed moving steel wires to drive a slurry containing silicon carbide (SiC) abrasive particles in a circulating spray. The abrasive particles remove material through rolling and micro-cutting action on the silicon material, thereby cutting the silicon ingot into multiple silicon wafers for use in the manufacture of semiconductor chips.

[0003] In existing slurry multi-wire cutting processes, a common phenomenon is that the thickness of the silicon ingot entering the cutting edge is significantly less than the thickness exiting the cutting edge, forming what is known as "cutting edge taper." This phenomenon leads to excessive total thickness deviation (TTV) of the resulting silicon wafer, and further causes defects such as warping and edge chipping, thus seriously affecting the silicon wafer processing quality and yield.

[0004] Studies have shown that the root cause of the above problems lies in the continuous attenuation of the abrasive particle size in the mortar during the cutting process. In the initial stage of cutting, the mortar used is new mortar, with large and sharp silicon carbide abrasive particles, resulting in strong cutting force and a large amount of silicon material removed from the entry edge, leading to a thin entry edge. As the cutting process progresses, the abrasive particles in the mortar are continuously broken in the circulation, and the particle size gradually decreases, resulting in a gradual weakening of the cutting force. By the exit edge stage, the abrasive particle size has decreased significantly, leading to a reduction in the amount of silicon material removed from the exit edge, thus resulting in a thicker exit edge.

[0005] To address the aforementioned issues, existing technologies typically employ methods such as zoned gradient abrasive supply, dynamic adjustment of slurry concentration, and alteration of linear velocity to compensate for cutting force attenuation. However, these solutions often require complex modifications to existing cutting equipment, resulting in high implementation costs. Furthermore, while some methods involve setting buffer or heat dissipation layers on the silicon ingot end face, primarily to prevent edge chipping or improve heat dissipation, they do not address the active control of slurry abrasive particle size, thus failing to fundamentally eliminate the problem of blade thickness variation.

[0006] Patent CN121136388A primarily enhances cutting stability by improving the wire mesh structure (such as using oblique wire mesh), but it focuses on demolding or stability issues at the cutting end and does not address the precision control issue at the cutting front. Patent US20030047177A1 proposes setting a sacrificial layer in wire cutting equipment to reduce slice thickness variations and centerline deviation, but this solution has the following shortcomings: the sacrificial layer material is not clearly defined, and different materials have significant differences in hardness, modulus, and thermal properties, making the effect unreliable; the principle is not clearly described, only explaining the prevention of excessive kerf loss from the phenomena, lacking optimization basis for mechanisms such as initial wire mesh vibration and thermal expansion matching; and the process support scheme is lacking, failing to provide cutting parameters, bonding methods, and cleaning removal methods, resulting in insufficient feasibility and inability to be directly used in production.

[0007] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0008] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a pre-cutting layer for slurry multi-wire cutting of semiconductor silicon ingots, its preparation method and its application, to solve the problem of uneven cutting force caused by the attenuation of abrasive grain size in slurry multi-wire cutting of semiconductor silicon ingots, resulting in a thin entry edge and a thick exit edge taper.

[0009] To achieve the above and other related objectives, the present invention provides a pre-cutting layer for multi-wire cutting of semiconductor silicon ingots, wherein the pre-cutting layer is an epoxy resin-based composite material comprising the following components by mass percentage: 30% to 40% epoxy resin matrix, 3% to 7% toughening agent, 12% to 16% curing agent, 0.5% to 1.5% accelerator, and 40% to 50% inorganic hard filler.

[0010] Preferably, the epoxy resin matrix comprises bisphenol A type epoxy resin.

[0011] Preferably, the toughening agent comprises a polyurethane-modified epoxy resin.

[0012] Preferably, the curing agent is an acid anhydride-based curing agent.

[0013] Preferably, the accelerator is a tertiary amine accelerator.

[0014] Preferably, the inorganic hard filler includes SiC micro powder.

[0015] Preferably, the D50 particle size of the SiC micro powder is 5μm~8μm.

[0016] Preferably, the Vickers hardness of the pre-cut layer is 850~1050 HV.

[0017] Preferably, the thickness of the pre-cut layer is 3~8mm.

[0018] Preferably, the flatness of the pre-cut layer is ≤ ±0.02 mm.

[0019] Preferably, the groove surface of the pre-cutting layer matches the inlet face of the semiconductor silicon ingot to be cut.

[0020] In addition, the present invention also provides a method for preparing the above-mentioned pre-cut layer, the method comprising at least the following steps:

[0021] S1. The inorganic hard packing is dried and sieved to obtain the pretreated inorganic hard packing.

[0022] S2. Stir and mix the epoxy resin matrix and toughening agent, then add the pretreated inorganic hard filler in batches and disperse it by high-speed shearing. Then add the curing agent and accelerator and stir to form a uniform slurry.

[0023] S3. After degassing, the slurry is injected into the mold and leveled.

[0024] S4. The mold is subjected to stepped temperature curing, which includes at least a first heat preservation section of 80℃~100℃, a second heat preservation section of 110℃~130℃, and a third heat preservation section of 140℃~160℃.

[0025] S5. After cooling, the pre-cut layer is obtained through demolding, cutting, and surface polishing.

[0026] Preferably, the rotation speed of the high-speed shear dispersion in step S2 is 1000~1200 rpm, and the high-speed shear dispersion time is 10~20 min.

[0027] Preferably, the degassing process in step S3 is carried out under vacuum, wherein the vacuum degree of the vacuum environment is -0.090MPa~0.098MPa.

[0028] Preferably, in step S4, the first insulation section is cured for 0.5 to 1.5 hours.

[0029] Preferably, the second insulation section is cured for 1.5 to 2.5 hours.

[0030] Preferably, the third insulation section is cured for 2.5 to 3.5 hours.

[0031] Preferably, after the stepped temperature curing, a post-curing stage is further included, which specifically involves heating to 155~165℃ and holding at that temperature for 0.5~1.5h.

[0032] In addition, the present invention also provides an application of the above-mentioned pre-cutting layer in multi-wire cutting of semiconductor silicon ingot slurry, comprising the following steps:

[0033] The pre-cutting layer is attached to the inlet end face of the semiconductor silicon ingot to be cut;

[0034] The pre-cut layer and semiconductor silicon ingot are cut using a slurry multi-wire cutting process, and the segmented cutting process parameters are adjusted during the cutting process.

[0035] During the cutting of the pre-cut layer, the cutting line speed is controlled to be V1 and the cutting feed speed is controlled to be F1.

[0036] During the cutting into the semiconductor silicon ingot, the cutting line speed is controlled to be V2 and the cutting feed speed is controlled to be F2.

[0037] Among them, V2 > V1, F2 > F1.

[0038] Preferably, V1 is 12~15m / s and F1 is 0.3~0.5mm / min; V2 is 15~18m / s and F2 is 0.5~0.8mm / min.

[0039] As described above, the pre-cutting layer for multi-wire cutting of semiconductor silicon ingots, the preparation method thereof, and their applications have the following beneficial effects:

[0040] This invention provides an epoxy resin-based pre-cutting layer with embedded fine inorganic hard fillers. Through the synergistic effect of a semiconductor-grade epoxy resin matrix and high-purity fine SiC fillers in a specific ratio, the hardness of the pre-cutting layer matches that of the silicon ingot. It can effectively grind the coarse abrasive grains in the slurry and slowly and evenly release the internal fine SiC particles into the slurry to compensate for abrasive wear, thus maintaining stable cutting force from the source. At the same time, the pre-cutting layer uses semiconductor-grade materials that do not release metal ions, ensuring high cleanliness during the cutting process and avoiding contamination of the silicon wafer. In addition, the pre-cutting layer adopts a stepped temperature curing process, which effectively eliminates internal thermal stress and avoids product warping or cracking. The flatness of the prepared pre-cutting layer is ≤±0.02mm, the thickness tolerance is small, the hardness distribution is uniform, and the preparation process has a high degree of standardization, which can achieve mass production without special equipment, ensuring the consistency and reliability of product quality.

[0041] In this invention, a pre-cutting layer is adhered to the inlet face of the semiconductor silicon ingot to be cut, and the cutting line speed and feed speed are controlled in stages during cutting. In the pre-cutting layer stage, a low-speed, slow feed achieves coarse sand grinding and in-situ slow release of fine SiC, rapidly stabilizing the slurry particle size. Once the silicon ingot cutting stage begins, a high-speed, fast feed is switched to ensure cutting efficiency. Through the synergistic cooperation of the pre-cutting layer structure and the segmented process parameters, the slurry cutting force is made uniform and stable throughout the entire process, fundamentally eliminating the problem of thin inlet and thin outlet surfaces. The thick taper issue significantly improves the quality and yield of silicon wafer cutting. Actual measurements show that the thickness difference between the silicon ingot inlet and outlet is reduced to 1.5~3.0μm, and the total thickness deviation (TTV) of the silicon wafer is optimized to ≤5μm, effectively reducing warping and arc distortion, and significantly improving the appearance and dimensional consistency of the silicon wafer. In addition, this invention can achieve stable results simply by attaching a pre-cutting layer and controlling the linear speed and feed rate in segments. It does not require modification of the existing slurry multi-wire cutting system, has good compatibility, and significantly reduces modification costs. Attached Figure Description

[0042] Figure 1 The diagram shown is a schematic representation of the structure of the pre-cut layer in a specific embodiment of the present invention.

[0043] Figure 2 The diagram shows a pre-cutting layer attached to a semiconductor silicon ingot to be cut, as shown in a specific embodiment of the present invention.

[0044] Figure 3 The diagram shows a comparison of the changes in mortar particle size during the cutting process in Application Example 1 and Comparative Example 1 of this invention.

[0045] Figure 4 The diagram shows a comparison of the changes in mortar particle size during the cutting process in Application Example 1, Comparative Example 2, and Comparative Example 3 of this invention. (Component labeling explanation)

[0046] 10 silicon ingots 20 Pre-cut layer Detailed Implementation

[0047] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0048] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0049] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or equivalent to those described, apparatus, and materials in the embodiments of this invention may be used to implement the present invention.

[0050] Please see Figures 1-4 It should be noted that the illustrations provided in this embodiment are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0051] The present invention provides a pre-cutting layer for multi-wire cutting of semiconductor silicon ingot slurry, wherein the pre-cutting layer 20 is an epoxy resin-based composite material comprising the following components by mass percentage: 30%~40% epoxy resin matrix, 3%~7% toughening agent, 12%~16% curing agent, 0.5%~1.5% accelerator, and 40%~50% inorganic hard filler.

[0052] Specifically, the mass percentage of epoxy resin matrix can include any value within the range of 30%, 32%, 34%, 35%, 36%, 38%, 40%, etc.; the mass percentage of toughening agent can include any value within the range of 3%, 4%, 5%, 6%, etc.; the mass percentage of curing agent can include any value within the range of 12%, 13%, 14%, 15%, 16%, etc.; the mass percentage of accelerator can include any value within the range of 0.5%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.5%, etc.; and the mass percentage of inorganic rigid filler can include any value within the range of 40%, 42%, 44%, 45%, 46%, 48%, 50%, etc. The specific values ​​can be adjusted according to actual needs.

[0053] Specifically, the pre-cutting layer 20 of the present invention is composed of a composite material with the above-mentioned specific components and proportions. The core mechanism of the pre-cutting layer 20 for slurry multi-wire cutting of semiconductor silicon ingot 10 is "online grinding-slow release". In the initial stage of cutting, the coarse abrasive particles in the slurry cut the pre-cutting layer 20 first. Its edges are blunted and broken by mechanical grinding by the epoxy resin-based composite material and the inorganic hard filler uniformly dispersed therein, thus achieving "fine grinding". At the same time, the pre-cutting layer 20 itself will wear evenly, so that the inorganic hard filler embedded inside it will be gradually exposed and released into the slurry, replenishing the slurry with new fine-grained abrasive particles, thus achieving "slow release". Through this dual action, the particle size distribution of the slurry is adjusted to a stable state before the steel wire cuts into the silicon ingot 10, ensuring the consistency of the cutting force throughout the cutting process, thereby eliminating the difference in blade thickness from the root.

[0054] It should be noted that limiting the content range of each component is key to achieving the function of this invention. If the epoxy resin matrix is ​​too small, the system will be brittle and prone to cracking; if it is too large, the hardness and wear resistance will be insufficient. If the inorganic hard filler is too small, the grinding and slow-release effects will be poor; if it is too large, the composite material will have excessive viscosity, making it difficult to process and mold, and prone to agglomeration.

[0055] As an example, the epoxy resin matrix includes bisphenol A type epoxy resin.

[0056] Specifically, the bisphenol A type epoxy resins used are all semiconductor-grade bisphenol A type epoxy resins.

[0057] In a specific embodiment of the present invention, the epoxy resin matrix used is bisphenol A type liquid epoxy resin with the commercial model Shell Epon 828, which is an unmodified liquid epoxy resin synthesized from bisphenol A and epichlorohydrin. It is a pale yellow transparent liquid with a viscosity of about 12,000~14,000 mPa·s at 25°C and an epoxy equivalent of about 185~192 g / eq. Of course, in other examples, bisphenol A type epoxy resin of the same grade as Shell Epon 828 that can meet the cleanliness requirements of semiconductor grade can also be used.

[0058] As an example, the toughening agent includes polyurethane-modified epoxy resin.

[0059] As an example, the curing agent is an acid anhydride-based curing agent.

[0060] Preferably, the curing agent is selected from methyltetrahydrophthalic anhydride (MeTHPA).

[0061] As an example, the accelerator is a tertiary amine accelerator.

[0062] Preferably, the accelerator is selected from DMP-30 (2,4,6-tris(dimethylaminomethyl)phenol).

[0063] As an example, the inorganic hard filler includes SiC micro powder.

[0064] Specifically, SiC micro powder, as a hard phase, not only provides grinding action for coarse sand, but also serves as a source of fine abrasive particles for subsequent slow release.

[0065] As an example, the D50 particle size of the SiC micro powder is 5μm~8μm.

[0066] Specifically, the particle size range is matched with the hardness (HV1000~1200) and cutting requirements of the semiconductor silicon ingot 10 to be cut. If the particle size is too large, the grinding ability will be too strong, which will accelerate unnecessary wear of the pre-cut layer 20; if the particle size is too small, the grinding and slow-release effects will be insignificant. Preferably, the D50 particle size of the SiC micro powder is 6μm, the purity is ≥99.9%, and there is no obvious agglomeration.

[0067] As an example, the Vickers hardness of the pre-cut layer 20 is 850~1050HV.

[0068] Specifically, the Vickers hardness of the pre-cut layer 20 can include any value within the range of 850HV, 900HV, 950HV, 1000HV, 1050HV, etc.

[0069] As an example, the thickness of the pre-cut layer 20 is 3~8mm.

[0070] Specifically, the thickness of the pre-cut layer 20 can be any value within the range of 3mm, 4mm, 5mm, 6mm, 7mm or 8mm.

[0071] As an example, the flatness of the pre-cut layer 20 is ≤ ±0.02 mm.

[0072] Specifically, flatness can include values ​​within any range such as ±0.02mm, ±0.015mm, ±0.01mm, ±0.001mm, ±0.0001mm, and 0mm.

[0073] As an example, the groove surface of the pre-cutting layer 20 matches the inlet end face of the semiconductor silicon ingot 10 to be cut.

[0074] Specifically, for ease of installation and compatibility with existing equipment, the grooved surface of the pre-cutting layer 20 matches the inlet face of the semiconductor silicon ingot 10 to be cut. See also Figure 1 This is a schematic diagram of the pre-cut layer 20. Figure 2This is a schematic diagram of the structure of the pre-cutting layer 20 attached to the semiconductor silicon ingot 10 to be cut. The side of the pre-cutting layer 20 that contacts the silicon ingot 10 is a grooved surface. The grooved surface of the pre-cutting layer 20 matches the side of the silicon ingot 10 that contacts it (i.e. the cutting edge end face). When the silicon ingot 10 is cylindrical, the contact surface between the pre-cutting layer 20 and the silicon ingot 10 is an arc-shaped surface, and the length of the pre-cutting layer 20 is adapted to the length of the silicon ingot 10.

[0075] When in use, it can be temporarily bonded to the inlet end face of silicon ingot 10 using semiconductor-grade epoxy adhesive. During the cutting process, the pre-cutting layer 20 can be worn slowly and evenly without cracking, sticking to the wire, or releasing heavy metal ions, thus meeting the requirements of semiconductor-grade cleanliness. After cutting, it is removed along with the silicon waste without affecting the quality of silicon wafer processing.

[0076] In addition, the present invention also provides a method for preparing the above-mentioned pre-cut layer, the method comprising at least the following steps:

[0077] S1. The inorganic hard packing is dried and sieved to obtain the pretreated inorganic hard packing.

[0078] S2. Stir and mix the epoxy resin matrix and toughening agent, then add the pretreated inorganic hard filler in batches and disperse it by high-speed shearing. Then add the curing agent and accelerator and stir to form a uniform slurry.

[0079] S3. After degassing, the slurry is injected into the mold and leveled.

[0080] S4. The mold is subjected to stepped temperature curing, which includes at least a first heat preservation section of 80℃~100℃, a second heat preservation section of 110℃~130℃, and a third heat preservation section of 140℃~160℃.

[0081] S5. After cooling, the pre-cut layer 20 is obtained by demolding, cutting and surface polishing.

[0082] Specifically, step S1 is the pretreatment of the inorganic rigid filler. It is first dried at 100℃~140℃ (e.g., 100℃, 110℃, 120℃, 130℃, 140℃, etc.) for 1.5~2.5h (e.g., 1.5h, 2.0h, 2.5h, etc.) to remove surface adsorbed water. After drying, it is sieved through a 200-mesh sieve to remove agglomerated particles. Preferably, the drying process is carried out at 120℃ for 2h.

[0083] As an example, the high-speed shear dispersion in step S2 has a rotation speed of 1000~1200 rpm and a high-speed shear dispersion time of 10~20 min.

[0084] Specifically, step S2 is the ingredient preparation process. At room temperature, epoxy resin matrix and toughening agent are added sequentially to a mixing container and stirred at low speed (preferably, the stirring rate is 200~350 rpm) to ensure thorough mixing. Subsequently, pretreated inorganic hard filler is added in batches at 2-minute intervals. After each addition, high-speed shear dispersion is performed at a speed of 1000~1200 rpm (e.g., any value within the range of 1000 rpm, 1050 rpm, 1100 rpm, 1150 rpm, 1200 rpm, etc.) for 10~20 minutes (e.g., any value within the range of 10 min, 12 min, 14 min, 16 min, 18 min, 20 min, etc.) to ensure that the inorganic hard filler is uniformly dispersed in the epoxy resin matrix without precipitation or agglomeration. Afterward, curing agent and accelerator are added, and stirring is maintained at low speed (preferably, the stirring rate is 200~350 rpm) until well mixed, avoiding the inclusion of air bubbles.

[0085] As an example, the degassing process in step S3 is carried out in a vacuum environment, wherein the vacuum degree of the vacuum environment is -0.090MPa~0.098MPa.

[0086] Specifically, the slurry is transferred to a degassing container and degassed under a certain vacuum degree, which can be any value within the range of -0.090 MPa, -0.092 MPa, -0.094 MPa, -0.095 MPa, -0.097 MPa, -0.098 MPa, etc. The degassing time is preferably 10~15 min (e.g., 10 min, 11 min, 12 min, 13 min, 14 min, 15 min, etc.) until the slurry surface is calm and no visible bubbles are visible. After degassing, the slurry is poured into a pre-made mold, which is made of aluminum or PTFE and whose dimensions match the end face of the silicon ingot's cutting edge. The pouring thickness is controlled between 3mm and 8mm, and the slurry surface is smoothed with a scraper.

[0087] As an example, in step S4, the first insulation section is cured for 0.5~1.5h.

[0088] As an example, the second insulation section is cured for 1.5 to 2.5 hours.

[0089] As an example, the third insulation section is cured for 2.5 to 3.5 hours.

[0090] Specifically, stepped temperature curing effectively controls the reaction rate, gradually releases curing shrinkage stress, and prevents product warping and cracking, which is key to ensuring product flatness and mechanical properties. The temperature of the first insulation stage can be any value within the range of 80℃, 85℃, 90℃, 95℃, 100℃, etc., and the curing time can be 0.5h, 0.8h, 1.0h, 1.2h, 1.5h, etc., preferably 80℃ for 1h; the temperature of the second insulation stage can be 110℃, 11... The temperature of the third insulation stage can be any value within the range of 5℃, 120℃, 125℃, 130℃, etc., and the curing and heat preservation time can be 1h, 1.8h, 2.0h, 2.2h, 2.5h, etc., preferably 120℃, 2h; the temperature of the third insulation stage can be any value within the range of 140℃, 145℃, 150℃, 155℃, 160℃, etc., and the curing and heat preservation time can be 2.5h, 2.8h, 3.0h, 3.2h or 3.5h, etc., preferably 150℃, 3h.

[0091] As an example, after the stepped temperature curing, there is also a post-curing stage, which specifically involves heating to 155~165℃ and holding at that temperature for 0.5~1.5h.

[0092] Specifically, after completing the aforementioned stepped curing, a post-curing process is included. Post-curing involves raising the temperature to 155-165℃, for example, 155℃, 160℃, or 165℃, and then curing and holding at that temperature for 0.5h, 0.8h, 1.0h, 1.2h, or 1.5h, preferably at 160℃ for 1h. This post-curing allows for more complete cross-linking of the resin system, further improving the overall hardness and wear resistance of the material.

[0093] In addition, step S5 involves naturally cooling the cured pre-cut layer 20 to room temperature and demolding it from the mold; then cutting it with wire cutting or a blade until the final pre-cut layer 20 is completely matched with the inlet end face of the silicon ingot 10, and then lightly grinding its surface to ensure that the flatness is ≤ ±0.02mm.

[0094] In addition, the present invention also provides an application of the above-mentioned pre-cutting layer in multi-wire cutting of semiconductor silicon ingot slurry, comprising the following steps:

[0095] The pre-cutting layer 20 is attached to the inlet end face of the semiconductor silicon ingot 10 to be cut;

[0096] The pre-cut layer 20 and the semiconductor silicon ingot 10 are cut using a slurry multi-wire cutting process, and the segmented cutting process parameters are adjusted during the cutting process.

[0097] During the cutting of the pre-cut layer 20, the cutting line speed is controlled to be V1 and the cutting feed speed is controlled to be F1.

[0098] During the cutting into the semiconductor silicon ingot 10, the cutting line speed is controlled to be V2 and the cutting feed speed is controlled to be F2;

[0099] Among them, V2 > V1, F2 > F1.

[0100] Specifically, the pre-cutting layer 20 has a Vickers hardness of 850HV~1050HV, a thickness of 3~8mm, and a flatness of ≤±0.02mm. It can be slowly and evenly worn down and can be temporarily attached to the inlet end face of the silicon ingot 10. During the cutting process, it can achieve the grinding of coarse sand and the slow release of fine sand through its own wear, thereby stabilizing the cutting force of the sand and eliminating the thickness difference of the inlet and outlet.

[0101] In the initial cutting stage, the steel wire carries the mortar to first contact the pre-cutting layer 20. Since the hardness of the pre-cutting layer 20 is close to that of the silicon ingot 10, the coarse SiC abrasive particles in the mortar are mechanically ground by the matrix material of the pre-cutting layer 20 and the fine SiC particles embedded inside during the cutting process. The edges of the coarse abrasive particles are rounded, and large particles are broken, thus achieving the grinding of coarse abrasive. As the cutting progresses, the epoxy resin matrix of the pre-cutting layer 20 is slowly and uniformly worn, and the fine SiC particles embedded inside are gradually released into the mortar, replenishing the fine abrasive particles in the mortar that are reduced due to breakage, thus achieving the online slow release of fine abrasive particles in the mortar. When the steel wire cuts to the silicon ingot 10... At this time, the abrasive particles in the mortar have formed a uniform particle size distribution through the grinding and slow-release effect of the pre-cutting layer 20, and the cutting force tends to be stable. Throughout the cutting process, the cutting force of the mortar remains consistent, thereby completely eliminating the thickness difference problem of the inlet being too thin due to the strong cutting force of coarse sand and the outlet being too thick due to the weak cutting force of fine sand, thus improving the uniformity of silicon wafer thickness. In order to match the wear rate of the pre-cutting layer 20 and the mortar particle size control rhythm, the linear speed and cutting feed speed of the multi-wire cutting machine need to be precisely controlled. It is necessary to ensure "low-speed grinding in the pre-cutting stage and high-speed and efficient cutting in the silicon ingot stage 10" to ensure that the mortar particle size control is synchronized with the cutting process.

[0102] Specifically, the mechanism of the segmented control strategy is as follows: In the stage of cutting the pre-cutting layer 20, sufficient time needs to be allowed for the "grinding-slow release" process. Therefore, a lower linear speed and feed rate are adopted to avoid cutting through the pre-cutting layer 20 too quickly and to ensure that its function is fully utilized. Once the silicon ingot 10 is cut, the slurry particle size has stabilized, and the linear speed and feed rate can be increased to significantly improve the cutting efficiency. This process matching of "low-speed grinding in the front stage and high-speed cutting in the back stage" is an indispensable part of the overall technical solution of this invention.

[0103] In a specific embodiment of the present invention, by controlling the slurry particle size online through the pre-cutting layer 20 and matching the segmented cutting parameters, the thickness difference between the inlet and outlet of the silicon ingot 10 is significantly reduced from 5-15 μm in conventional processes to 1.5-3.0 μm, fundamentally solving the taper problem of a thin inlet and a thick outlet. The total thickness deviation (TTV) of the silicon wafer is optimized from the conventional 12-20 μm to ≤5 μm, a reduction of over 60%, effectively reducing warping and arc distortion, and significantly improving the appearance and dimensional consistency of the silicon wafer. Due to the significant reduction in defects such as thickness deviation, edge chipping, and microcracks, the overall silicon wafer processing yield is increased by 10%-15% compared to traditional processes, greatly reducing rework and waste. The process is efficient and cost-effective. Furthermore, stable cutting results can be achieved simply by attaching the pre-cutting layer 20 and adjusting the cutting line speed and feed rate in segments. No modifications to the slurry circulation system, spray structure, or main unit structure are required. It is compatible with all existing slurry multi-wire cutting machines, resulting in extremely low modification costs. In addition, the pre-cutting layer 20 uses semiconductor-grade epoxy resin and high-purity SiC micro powder, resulting in no metal ion precipitation and no debris contamination. The cutting process ensures uniform wear without wire sticking or chipping, and there is no secondary pollution to the silicon wafer or the cutting environment. During the cutting process, the cutting force remains stable without frequent replenishment of new slurry, improving slurry utilization and reducing silicon material waste caused by thickness deviations. Overall, the processing cost per wafer decreases by 5% to 8%.

[0104] For example, V1 is 12~15m / s, F1 is 0.3~0.5mm / min; V2 is 15~18m / s, F2 is 0.5~0.8mm / min.

[0105] Specifically, in the pre-cutting layer 20 stage, the linear speed is controlled at 12~15 m / s (including any value within the range of 12 m / s, 13 m / s, 14 m / s, 15 m / s, etc.); in the silicon ingot 10 stage, the linear speed is adjusted to 15~18 m / s (including any value within the range of 15 m / s, 16 m / s, 17 m / s, 18 m / s, etc.). This gradual increase in linear speed prevents the pre-cutting layer 20 from wearing out too quickly, resulting in insufficient grinding of the coarse abrasive, and also prevents edge chipping of the silicon wafer caused by excessively low linear speeds when cutting the silicon ingot 10. In the pre-cutting layer 20 stage, the feed rate is controlled at 0.3~0.5 mm / min (including any value within the range of 0.3 mm / min, 0.35 mm / min, 0.4 mm / min, 0.45 mm / min, 0.5 mm / min, etc.); in the silicon ingot 10 stage, the feed rate is adjusted to 0.5~0.8 mm / min (including any value within the range of 0.5 mm / min, 0.6 mm / min, etc.). (Values ​​within any range such as mm / min, 0.7 mm / min, 0.8 mm / min, etc.); the feed rate and linear velocity are matched to ensure that the grinding and slow-release effects of the pre-cut layer 20 are fully utilized, while ensuring the efficiency and quality of silicon wafer cutting.

[0106] To better understand the pre-cutting layer, preparation method, and application of the semiconductor silicon ingot slurry multi-wire cutting in this invention, the following description, with reference to specific embodiments, illustrates the pre-cutting layer, preparation method, and application of the semiconductor silicon ingot slurry multi-wire cutting in this invention. It should be noted that these embodiments are merely descriptive and do not limit the invention in any way.

[0107] The raw materials used in the following examples are all commercially available semiconductor-grade products, all use conventional slurry multi-wire cutting technology, and all use the same slurry system.

[0108] Example 1

[0109] This embodiment provides a pre-cutting layer for multi-wire cutting of semiconductor silicon ingots and its preparation method. The pre-cutting layer 20 is an epoxy resin-based composite material, comprising the following components by mass percentage: epoxy resin matrix (ShellEpon828 semiconductor-grade bisphenol A type liquid epoxy resin) 35%, toughening agent (polyurethane modified epoxy resin) 5%, curing agent (methyltetrahydrophthalic anhydride) 14%, accelerator (DMP-30) 1%, and inorganic hard filler (SiC micro powder) 45%; wherein, the D50 particle size of the SiC micro powder is 6μm and the purity is ≥99.9%.

[0110] Its preparation method specifically includes the following steps:

[0111] S1. Place the SiC micro powder in an oven and dry it at 120℃ for 2 hours to remove the adsorbed water on the surface of the micro powder. After drying, pass it through a 200-mesh sieve to remove agglomerated particles and obtain the pretreated SiC micro powder.

[0112] S2. At room temperature, add ShellEpon828 semiconductor-grade bisphenol A liquid epoxy resin and polyurethane-modified epoxy resin sequentially to a mixing container, and stir at a low speed of 300 rpm for 5 minutes to ensure thorough and uniform mixing. Then, add the pretreated SiC micro powder to the mixture in three batches, with a 2-minute interval between each addition. After each addition, shear and disperse at a high speed of 1000-1200 rpm for 15 minutes to ensure uniform dispersion of the SiC micro powder and the formation of a dispersion system free of precipitation and agglomeration. Then, add methyltetrahydrophthalic anhydride and DMP-30 to the dispersion system and stir at a low speed of 300 rpm for 5 minutes to form a homogeneous slurry.

[0113] S3. Transfer the slurry to a degassing container and place it in a vacuum environment with a vacuum degree of -0.095MPa for 10~15 minutes to degas until the material surface is calm and there are no visible bubbles. Pour the degassed slurry into a preset mold (the mold is made of PTFE and its size matches the end face of the silicon ingot 10 inlet blade) with a pouring thickness of 5mm. Use a scraper to smooth the surface of the material.

[0114] S4. Place the mold in an oven for stepped temperature curing. First, cure at 80℃ for 1 hour, then increase the temperature to 129℃ for 2 hours, and then increase the temperature to 150℃ for 3 hours. After the stepped temperature curing is completed, increase the oven temperature to 160℃ for 1 hour to further improve the hardness and wear resistance of the pre-cut layer 20.

[0115] S5. Allow the mold to cool naturally to room temperature. After demolding, cut it to a size that perfectly matches the end face of the silicon ingot 10 using wire cutting or a blade. Then, finely grind its surface to ensure that the flatness is ≤ ±0.02mm, thus obtaining the pre-cut layer 20.

[0116] Performance testing:

[0117] Performance testing showed that the grooved surface of the pre-cutting layer 20 prepared in this embodiment matches the inlet end face of the semiconductor silicon ingot 10 to be cut, and can be perfectly attached to the inlet end face of the semiconductor silicon ingot 10; the pre-cutting layer 20 has a Vickers hardness of 920HV, a flatness of ±0.015mm, a thickness of 5mm, and a cleanliness that meets semiconductor-grade requirements.

[0118] Example 2

[0119] This embodiment provides a pre-cutting layer for multi-wire cutting of semiconductor silicon ingots and its preparation method. The pre-cutting layer 20 is an epoxy resin-based composite material. The SiC micro powder used has a D50 particle size of 8μm. Other components and proportions are the same as in Example 1, and will not be repeated here.

[0120] The difference between the preparation method of the pre-cut layer in this embodiment and that in embodiment 1 is that the casting thickness in step S3 is 6 mm. Other methods and steps are the same as in embodiment 1, and will not be repeated here.

[0121] Performance testing:

[0122] Performance testing showed that the grooved surface of the pre-cutting layer 20 prepared in this embodiment matches the inlet end face of the semiconductor silicon ingot 10 to be cut, and can be perfectly attached to the inlet end face of the semiconductor silicon ingot 10; the pre-cutting layer 20 has a Vickers hardness of 1020HV, a flatness of ±0.018mm, a thickness of 6mm, and a cleanliness that meets semiconductor-grade requirements.

[0123] Application Example 1

[0124] This application example provides a method for multi-wire cutting of semiconductor silicon ingots using slurry. The pre-cutting layer prepared in Example 1 is applied to the multi-wire cutting of semiconductor silicon ingots using slurry, and the method specifically includes the following steps:

[0125] Semiconductor-grade epoxy adhesive was used to bond the pre-cutting layer 20 from Example 1 to the inlet end face of the 8-inch monocrystalline silicon ingot 10 to be cut;

[0126] The pre-cut layer 20 and the monocrystalline silicon ingot 10 were cut using a conventional slurry multi-wire cutting process. During the cutting process, the segmented cutting process parameters were adjusted. In the stage of cutting the pre-cut layer 20, the cutting line speed was controlled at 13 m / s and the cutting feed speed was controlled at 0.4 mm / min. In the stage of cutting into the monocrystalline silicon ingot 10, the cutting line speed was controlled at 16 m / s and the cutting feed speed was controlled at 0.6 mm / min.

[0127] Post-cutting tests showed that the thickness difference between the exit and entry edges was 1.8 μm; the slurry particle size fluctuation range was 0.4 μm; the cutting yield was 92.5%; the pre-cutting layer 20 showed uniform wear and no chipping; the total thickness deviation (TTV) of the silicon wafer was optimized from the conventional 12~20 μm to ≤5 μm, a reduction of over 60%, effectively reducing warping and arc distortion, and significantly improving the appearance and dimensional consistency of the silicon wafer; and the yield of the silicon wafer was 12% higher than that of Comparative Example 1.

[0128] Application Example 2

[0129] This application example provides a method for multi-wire cutting of semiconductor silicon ingots using slurry. The pre-cutting layer 20 prepared in Example 2 is applied to the multi-wire cutting of semiconductor silicon ingots using slurry. The specific steps are different from those in Application Example 1 in that: in the stage of cutting the pre-cutting layer 20, the cutting line speed is controlled at 14 m / s and the cutting feed speed is controlled at 0.35 mm / min; in the stage of cutting into the single crystal silicon ingot 10, the cutting line speed is controlled at 17 m / s and the cutting feed speed is controlled at 0.7 mm / min; the other steps are the same as those in Application Example 1, and will not be repeated here.

[0130] After cutting, the thickness difference between the exit edge thickness and the entry edge thickness was 2.1μm, the cutting yield was 90%, the pre-cut layer 20 showed uniform wear and no chipping; the total thickness deviation (TTV) of the silicon wafer was ≤6μm, and the yield of the silicon wafer was 10% higher than that of Comparative Example 1.

[0131] Comparative Example 1

[0132] This comparative example provides a method for multi-wire cutting of semiconductor silicon ingots using slurry, the specific cutting method including:

[0133] Provide 8-inch monocrystalline silicon ingots 10 to be cut (without bonded pre-cut layer 20);

[0134] The monocrystalline silicon ingot 10 was cut using a conventional slurry multi-wire cutting process (the same as in Application Example 1), with a cutting line speed of 15 m / s and a cutting feed speed of 0.6 mm / min throughout the process.

[0135] After cutting, the test results showed that the thickness difference between the exit edge thickness and the entry edge thickness was 12μm, the cutting yield of the silicon wafer was 82%, and the total thickness deviation (TTV) of the silicon wafer was ≥15μm.

[0136] See Figure 3 The figure shows a comparison of the mortar particle size changes during the cutting process between Application Example 1 and Comparative Example 1. As can be seen from the figure, in Application Example 1, the mortar D50 particle size can be stabilized at 8.6-9.0 μm after the cutting stroke is 5 mm, and the mortar particle size fluctuation range is 0.4 μm throughout the process; while in Comparative Example 1, the mortar D50 particle size continuously decreases to 4.8-6.2 μm, and the cutting force decreases significantly.

[0137] Comparative Example 2

[0138] This comparative example provides a method for multi-wire cutting of semiconductor silicon ingots using slurry. The pre-cutting layer 20 prepared in Example 1 is applied to the multi-wire cutting of semiconductor silicon ingots using slurry. The specific steps are different from those in Application Example 1 in that: during the cutting of the pre-cutting layer 20, the cutting line speed is controlled to be 16 m / s and the cutting feed speed is 0.6 mm / min; the other steps are the same as those in Application Example 1 and will not be repeated here.

[0139] After cutting, the test results showed that the thickness difference between the exit edge thickness and the entry edge thickness was 6.7μm, the mortar particle size fluctuation range was 1.9μm, the cutting yield was 84.2%, and the pre-cut layer 20 showed local breakage and detachment.

[0140] Comparative Example 3

[0141] This comparative example provides a method for multi-wire cutting of semiconductor silicon ingots using slurry. The pre-cutting layer 20 prepared in Example 1 is applied to the multi-wire cutting of semiconductor silicon ingots using slurry. The specific steps are different from those in Application Example 1 in that: during the cutting of the pre-cutting layer 20, the cutting line speed is controlled to be 13 m / s and the cutting feed speed is 1 mm / min; the other steps are the same as those in Application Example 1 and will not be repeated here.

[0142] After cutting, the test results showed that the thickness difference between the exit edge thickness and the entry edge thickness was 5.2μm, the mortar particle size fluctuation range was 1.5μm, the cutting yield was 85.6%, and the pre-cutting layer 20 was worn too quickly and not sufficiently ground.

[0143] See Figure 4The graph shows a comparison of the changes in mortar particle size during the cutting process in Application Example 1, Comparative Example 2, and Comparative Example 3. As can be seen from the graph, only Application Example 1 shows that the mortar particle size gradually stabilizes during the cutting process. In Comparative Example 2, the excessively fast cutting line speed leads to insufficient release of silicon carbide fine powder in the pre-cut layer, which fails to maintain the stability of the mortar particle size in the cutting fluid. The same applies to Comparative Example 3, where an excessively fast cutting feed speed also affects the sufficiency of silicon carbide fine powder release in the pre-cut layer.

[0144] In summary, this invention provides an epoxy resin-based pre-cutting layer with embedded fine inorganic hard fillers. Through the synergistic effect of a semiconductor-grade epoxy resin matrix and high-purity fine SiC fillers in a specific ratio, its hardness matches that of the silicon ingot, effectively grinding the coarse abrasive grains in the mortar. Its slow and uniform wear characteristics can release the internal fine SiC particles into the mortar, replenishing abrasive wear and maintaining the cutting force temperature from the source. Furthermore, the pre-cutting layer formula uses semiconductor-grade materials that do not release metal ions, ensuring high crystallinity during the cutting process and preventing contamination of the silicon wafer. Moreover, the pre-cutting layer adopts a stepped temperature curing process, effectively eliminating internal thermal stress and preventing product warping or cracking. The prepared pre-cutting layer has a flatness of ≤±0.02mm, small thickness tolerance, and uniform hardness distribution. The preparation process has a high degree of standardization, enabling mass production without special equipment, ensuring the consistency and reliability of product quality. In this invention, a pre-cutting layer is adhered to the inlet face of the semiconductor silicon ingot to be cut. During cutting, the cutting line speed and feed rate are controlled in stages. In the pre-cutting layer stage, a low-speed, slow feed is used to achieve coarse sand grinding and in-situ slow release of fine SiC, allowing the slurry particle size to quickly stabilize. After entering the silicon ingot cutting stage, the feed rate is switched to high speed to ensure cutting efficiency. Through the synergistic cooperation of the pre-cutting layer structure and the segmented process parameters, the slurry cutting force is made uniform and stable throughout the process, eliminating the tapered shape of a thin inlet and thick outlet from the root cause. This invention addresses the issue of thickness, significantly improving silicon wafer cutting quality and yield. It successfully reduces the thickness difference between the ingot's entry and exit points to 1.5~3.0μm, optimizing the total thickness deviation (TTV) of the silicon wafer to ≤5μm. This effectively reduces warping and arcing distortion, significantly improving the appearance and dimensional consistency of the silicon wafer. Furthermore, stable results can be achieved simply by attaching a pre-cutting layer and segmenting the linear speed and feed rate, without requiring modifications to existing slurry multi-wire cutting systems, thus significantly reducing modification costs. Therefore, this invention effectively overcomes the various shortcomings of existing technologies and has high industrial application value.

[0145] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

Claims

1. A pre-cutting layer for multi-wire cutting of semiconductor silicon ingot slurry, characterized in that: The pre-cut layer is an epoxy resin-based composite material, comprising the following components by mass percentage: 30%~40% epoxy resin matrix, 3%~7% toughening agent, 12%~16% curing agent, 0.5%~1.5% accelerator, and 40%~50% inorganic hard filler.

2. The pre-cutting layer for multi-wire cutting of semiconductor silicon ingots according to claim 1, characterized in that: The epoxy resin matrix includes bisphenol A type epoxy resin; And / or, the toughening agent comprises polyurethane-modified epoxy resin; And / or, the curing agent is an acid anhydride curing agent; And / or, the accelerator is a tertiary amine accelerator; And / or, the inorganic hard filler includes SiC micro powder.

3. The pre-cutting layer for multi-wire cutting of semiconductor silicon ingots according to claim 2, characterized in that: The D50 particle size of the SiC micro powder is 5μm~8μm.

4. The pre-cutting layer for multi-wire cutting of semiconductor silicon ingots according to claim 1, characterized in that: The Vickers hardness of the pre-cut layer is 850~1050HV; And / or, the thickness of the pre-cut layer is 3~8mm; And / or, the flatness of the pre-cut layer is ≤ ±0.02 mm.

5. The pre-cutting layer for multi-wire cutting of semiconductor silicon ingots according to any one of claims 1 to 4, characterized in that: The grooved surface of the pre-cutting layer matches the inlet face of the semiconductor silicon ingot to be cut.

6. A method for preparing a pre-cut layer as described in any one of claims 1 to 5, characterized in that: The preparation method includes at least the following steps: S1. The inorganic hard packing is dried and sieved to obtain the pretreated inorganic hard packing. S2. Stir and mix the epoxy resin matrix and toughening agent, then add the pretreated inorganic hard filler in batches and disperse it by high-speed shearing. Then add the curing agent and accelerator and stir to form a uniform slurry. S3. After degassing, the slurry is injected into the mold and leveled. S4. The mold is subjected to stepped temperature curing, which includes at least a first heat preservation section of 80℃~100℃, a second heat preservation section of 110℃~130℃, and a third heat preservation section of 140℃~160℃. S5. After cooling, the pre-cut layer is obtained through demolding, cutting, and surface polishing.

7. The method for preparing the pre-cut layer according to claim 6, characterized in that: The high-speed shear dispersion in step S2 has a rotation speed of 1000~1200 rpm and a high-speed shear dispersion time of 10~20 min.

8. The method for preparing the pre-cut layer according to claim 6, characterized in that: The degassing process described in step S3 is carried out under vacuum, wherein the vacuum degree of the vacuum environment is -0.090MPa~0.098MPa.

9. The method for preparing the pre-cut layer according to claim 6, characterized in that: In step S4, the first insulation section is cured for 0.5~1.5 hours; And / or, cure in the second insulation section for 1.5~2.5 hours; And / or, cure in the third insulation section for 2.5~3.5 hours; And / or, after the stepped temperature curing, a post-curing stage is also included, specifically, the temperature is raised to 155~165℃ and held for 0.5~1.5h.

10. An application of the pre-cutting layer as described in any one of claims 1 to 5 in multi-wire cutting of semiconductor silicon ingots, characterized in that: Includes the following steps: The pre-cutting layer is attached to the inlet end face of the semiconductor silicon ingot to be cut; The pre-cut layer and semiconductor silicon ingot are cut using a slurry multi-wire cutting process, and the segmented cutting process parameters are adjusted during the cutting process. During the cutting of the pre-cut layer, the cutting line speed is controlled to be V1 and the cutting feed speed is controlled to be F1. During the cutting into the semiconductor silicon ingot, the cutting line speed is controlled to be V2 and the cutting feed speed is controlled to be F2. Among them, V2 > V1, F2 > F1.

11. The application of the pre-cutting layer according to claim 10 in multi-wire cutting of semiconductor silicon ingots, characterized in that: V1 is 12~15m / s, F1 is 0.3~0.5mm / min; V2 is 15~18m / s, and F2 is 0.5~0.8mm / min.

Images