A high-holding force anti-falling brazed diamond disc for CMP polishing pad trimming and a preparation method thereof

Abstract

The present application belongs to the technical field of chemical mechanical polishing (CMP) auxiliary tool preparation, and discloses a high-holding-force anti-falling brazed diamond disc for CMP polishing pad trimming and a preparation method thereof. The high-holding-force anti-falling brazed diamond disc for CMP polishing pad trimming comprises a base body, diamond abrasive grains and a double-layer solder structure for connecting the diamond abrasive grains and the base body, the double-layer solder structure is composed of a bottom layer of ductile solder and an upper layer of wear-resistant solder, the diamond abrasive grains are partially embedded in the double-layer solder structure, the embedding depth is 1 / 3-1 / 2 of the particle size of the diamond abrasive grains, the bottom layer of ductile solder is tightly combined with the base body, and the upper layer of wear-resistant solder wraps the bottom part of the exposed part of the diamond abrasive grains. In this way, a double-holding structure of "bottom fixation and upper protection" is formed, the diamond abrasive grains are ensured not to fall off under the action of periodic grinding force, and the wafers are prevented from being scratched by residues in the polishing pad.

Description

Technical Field

[0001] This invention relates to the field of chemical mechanical polishing (CMP) auxiliary tool preparation technology, specifically to a high-holding-force anti-detachment brazed diamond disc for CMP polishing pad dressing and its preparation method, and more particularly to a high-holding-force anti-detachment brazed diamond disc used for polishing pad dressing during CMP process, which can effectively prevent diamond detachment and avoid wafer scratches and its preparation method. Background Technology

[0002] Chemical mechanical polishing (CMP) is an indispensable surface planarization technology in semiconductor manufacturing and precision component processing. Its core principle is to achieve high-precision surface planarization of the workpiece (such as a semiconductor wafer) through the synergistic effect of mechanical polishing and chemical etching between the polishing pad and the workpiece. During CMP processing, the polishing pad may experience surface wear, decreased flatness, and abnormal roughness after long-term use. Regular dressing with diamond discs is necessary to restore the surface condition of the polishing pad and ensure the accuracy and consistency of subsequent wafer processing.

[0003] As a core tool for CMP polishing pad dressing, the performance of diamond discs directly affects the dressing effect of the polishing pad and the processing quality of the wafer. Currently, most existing CMP dressing diamond discs use a single nickel-based solder layer to connect the diamond abrasive grains to the substrate. Among them, BNi-2 series nickel-based solders have become the mainstream choice due to their excellent wear resistance and good high-temperature stability. However, traditional single nickel-based solders have inherent defects: to ensure wear resistance, the solder contains a high amount of boron and silicon, which easily precipitates hard and brittle phases such as CrB and Ni3B, resulting in insufficient toughness of the solder layer. During the polishing pad dressing process, the diamond abrasive grains are subjected to periodic grinding forces, causing slight "shaking." This repeated mechanical action continuously acts on the solder layer, easily leading to brittle fracture of the solder layer, and thus causing the diamond abrasive grains to detach. Detached diamond abrasive grains can remain in the pores of the polishing pad. During subsequent polishing of the wafer, these residual grains become hard impurities, scratching the wafer surface under polishing pressure. This results in defects such as scratches and breakage, reducing wafer yield and increasing semiconductor manufacturing costs. Furthermore, diamond grain shedding also reduces the dressing efficiency and shortens the lifespan of diamond discs, leading to more frequent disc replacements and further increasing energy consumption and costs.

[0004] Therefore, developing a brazed diamond disk that is suitable for CMP polishing pad dressing scenarios, can ensure the wear resistance of the solder layer and has excellent toughness, and can firmly hold the diamond and avoid wafer scratches has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the technical shortcomings of CMP polishing pad dressing, where a single solder layer on a diamond disc cannot simultaneously achieve both wear resistance and toughness, resulting in insufficient diamond holding force, easy diamond detachment, and subsequent diamond residue in the polishing pad that scratches the wafer. This invention provides a high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing and its preparation method. The brazed diamond disc of this invention, through a double-layer heterogeneous nickel-based solder structure design, achieves both "wear-resistant protection" and "toughness fixation," fundamentally solving the problems of diamond detachment and wafer scratching. It also extends the service life of the diamond disc and improves the dressing efficiency of CMP polishing pads.

[0006] To achieve the objectives of this invention, the high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing comprises a substrate, diamond abrasive grains, and a double-layer solder structure for connecting the diamond abrasive grains and the substrate. The double-layer solder structure consists of a bottom tough solder layer and an upper wear-resistant solder layer. The diamond abrasive grains are partially embedded in the double-layer solder structure to a depth of 1 / 3 to 1 / 2 of the diamond abrasive grain diameter. The bottom tough solder layer is tightly bonded to the substrate, and the upper wear-resistant solder layer covers the exposed bottom portion of the diamond abrasive grains. This forms a dual-holding structure of "bottom layer fixation, upper layer protection," ensuring that the diamond abrasive grains do not detach under cyclic abrasive force, preventing them from remaining in the polishing pad and scratching the wafer.

[0007] Furthermore, in some embodiments of the present invention, the underlying toughness solder layer is a modified nickel-based solder with added copper or cobalt powder. The modified nickel-based solder uses BNi-2 nickel-based solder as a matrix, with 1-3 wt% electrolytic copper powder or 2-5 wt% cobalt powder added. The boron content and silicon content in the BNi-2 nickel-based solder are adjusted to 2.5-3.0 wt% and 2.5-3.0 wt%, respectively, so that the silicon / boron molar ratio is 1.0-1.4. This suppresses the precipitation of hard and brittle phases, improves the toughness of the solder layer, and allows it to withstand the periodic "shaking" mechanical action of diamond abrasive grains during CMP polishing pad dressing, thus preventing brittle fracture of the solder layer.

[0008] Furthermore, in some embodiments of the present invention, the upper wear-resistant solder layer is a high wear-resistant nickel-based solder, using BNi-2 standard nickel-based solder (Cr 6~8wt%, Si 2.5~3.5wt%, B 2.5~3.5wt%, Fe 2.5~3.5wt%, Ni balance), which has excellent wear resistance and can prevent the solder layer from wearing out rapidly during the CMP polishing pad dressing process, thus avoiding premature exposure and detachment of diamond abrasive grains.

[0009] Furthermore, in some embodiments of the present invention, the thickness of the underlying tough solder layer is 1 / 3 to 1 / 2 of the diamond grain size.

[0010] Furthermore, in some embodiments of the present invention, the particle size of the copper powder is 1~5μm, and the particle size of the cobalt powder is 1~5μm.

[0011] Furthermore, in some embodiments of the present invention, the thickness of the upper wear-resistant solder layer is 1 / 3 to 1 / 2 of the thickness of the lower toughness solder layer.

[0012] Furthermore, in some embodiments of the present invention, the diamond abrasive grains are hexoctahedral single-crystal diamonds that have undergone surface purification treatment; preferably, the surface purification treatment is: firstly, acid washing is used to remove surface oxides and impurities, and then high-temperature treatment is used to remove surface adsorbates, thereby improving the wetting and bonding performance between the diamond and the solder layer, further enhancing the holding force, and adapting to the high-precision requirements of CMP polishing pad dressing.

[0013] Furthermore, in some embodiments of the present invention, the substrate is made of stainless steel or nickel-based high-temperature alloy; preferably, the surface roughness Ra of the substrate is ≤0.8μm; preferably, the surface of the substrate is treated by grinding, degreasing and derusting to ensure the bonding strength between the solder layer and the substrate, and to avoid the substrate and solder layer peeling off during the finishing process, which would affect the service life of the diamond disc.

[0014] Preferably, in some embodiments of the present invention, 0.1~0.5wt% of niobium powder is added to the bottom tough solder layer to transform the CrB and Ni3B hard and brittle phases precipitated in the solder into dispersed strengthening phases such as NbB2 and NbC, thereby further improving the toughness and high-temperature stability of the solder layer without affecting the wettability of the solder, and adapting to the continuous high-temperature environment during the CMP dressing process.

[0015] On the other hand, the present invention also provides a method for preparing the aforementioned high-holding-force, anti-detachment brazed diamond disk for CMP polishing pad dressing, the method comprising the following steps: (1) Substrate pretreatment: Select stainless steel or nickel-based high-temperature alloy as the substrate, and perform grinding, degreasing and rust removal on the substrate surface to ensure the reliability of the bonding between the substrate and the solder layer; (2) Solder preparation: ① Preparation of the bottom toughness solder: Take BNi-2 nickel-based solder powder, add 1~3wt% electrolytic copper powder or 2~5wt% cobalt powder in proportion, optionally, to further improve toughness, add 0.1~0.5wt% niobium powder, mix evenly, add an appropriate amount of anhydrous ethanol as a dispersant, and ultrasonically disperse to form a uniform solder slurry, ensuring that the modified elements are evenly distributed and improving the consistency of solder toughness; ② Preparation of upper layer wear-resistant solder: Take BNi-2 standard nickel-based solder powder, add anhydrous ethanol and binder (such as phenolic resin liquid), mix evenly to form solder slurry. The amount of binder added is 3~5% of the mass of solder powder, which is used to ensure the formability of solder layer and avoid peeling and cracking during the coating process. (3) Diamond pretreatment: Select hexagonal single crystal diamond abrasive grains to remove surface oxides and adsorbates, and set aside (to improve the wetting bond between diamond and solder layer and reduce the risk of detachment). (4) Solder coating and diamond arrangement: On the pretreated substrate surface, a bottom tough solder paste is coated by scraping method, and then dried to ensure the solder layer is formed. The pretreated diamond abrasive grains are evenly distributed on the surface of the bottom tough solder layer. The embedding depth of the diamond abrasive grains is controlled to be 1 / 3 to 1 / 2 of their grain size. The distribution density is adjusted according to the dressing requirements of the CMP polishing pad, taking into account both dressing efficiency and diamond holding stability. Apply an upper layer of wear-resistant solder paste to the bottom of the exposed part of the diamond abrasive grain and the surface of the bottom tough solder layer to ensure that the upper layer of solder covers the bottom of the diamond abrasive grain and does not obstruct the dressing surface of the diamond abrasive grain, thus ensuring the dressing effect of the polishing pad. (5) Vacuum brazing: The substrate coated with solder and diamond abrasive grains are placed in a vacuum brazing furnace so that the double-layer solder can be fully melted and react with the substrate and diamond abrasive grains to form a strong metallurgical bond, further enhancing the diamond holding force; (6) Post-weld treatment: After brazing, cool to room temperature and perform diffusion annealing to further eliminate the hard and brittle phase at the grain boundaries and improve the toughness and bonding strength of the solder layer; finally, grind and polish the surface of the workpiece to remove excess solder and obtain the finished brazed diamond disc, ensuring that the surface of the diamond disc is flat and can meet the high precision requirements of CMP polishing pad dressing.

[0016] Furthermore, in some embodiments of the present invention, the grinding, degreasing, and rust removal treatments are as follows: grinding until the surface roughness Ra ≤ 0.8 μm; degreasing using sodium hydroxide solution, soaking at 70-80°C for 30-40 minutes; rust removal using dilute hydrochloric acid, soaking for 10-15 minutes; after treatment, ultrasonic cleaning with deionized water until neutral; and vacuum drying at 80-90°C for later use.

[0017] Furthermore, in some embodiments of the present invention, the removal of surface oxides and adsorbents is carried out by roughening treatment with nitric acid solution at a temperature of 75~85°C for 20~30 minutes to remove surface oxides, followed by high-temperature treatment at 400~500°C for 25~35 minutes to remove surface adsorbents, and then cooling.

[0018] Furthermore, in some embodiments of the present invention, the thickness of the bottom toughness solder paste coating in step (4) is controlled to be 1 / 3 to 1 / 2 of the diamond particle size.

[0019] Furthermore, in some embodiments of the present invention, the drying in step (4) involves placing the coated material in an oven at 80-90°C for 10-15 minutes to remove the dispersant and moisture.

[0020] Furthermore, in some embodiments of the present invention, the thickness of the upper wear-resistant solder slurry coating in step (4) is controlled to be 1 / 3 to 1 / 2 of the thickness of the lower toughness solder.

[0021] Furthermore, in some embodiments of the present invention, in step (5), the sample is placed in a vacuum brazing furnace and heated to 1010-1080°C at a heating rate of 5-8°C / min, and held for 15-30 min.

[0022] Furthermore, in some embodiments of the present invention, in step (6), the workpiece is cooled to room temperature and then subjected to diffusion annealing at a cooling rate of 3~5℃ / min, and then placed in a heat treatment furnace at 880~920℃ for diffusion annealing for 1.5~2.5h.

[0023] Compared with the prior art, the advantages of the present invention are as follows: (1) The diamond holding force is significantly improved, eliminating wafer scratches: The bottom tough solder layer has excellent toughness, which can effectively buffer the periodic "shaking" mechanical action of diamond abrasive grains during CMP dressing, and avoid brittle fracture of the solder layer; the upper wear-resistant solder layer can prevent the solder from wearing out quickly and further strengthen the diamond. Under the dual action, the diamond abrasive grains are not easy to fall off, avoiding residue in the polishing pad, completely eliminating wafer scratches, improving wafer yield, and reducing semiconductor manufacturing risks. (2) Adapt to the needs of CMP polishing pad dressing and improve the dressing effect: The diamond abrasive grains are evenly distributed and firmly held, which can stably dress the polishing pad, effectively restore the flatness and roughness of the polishing pad, ensure the consistency and stability of CMP processing, and improve the wafer surface planarization accuracy. (3) Balancing wear resistance and service life: The upper layer of high wear-resistant nickel-based solder ensures the wear resistance of the diamond disc during finishing, which is suitable for the long-term finishing needs of the polishing pad. The lower layer of modified tough solder extends the crack resistance life of the solder layer. The two work together to extend the overall service life of the diamond disc by 30% to 50% compared with traditional products, reducing replacement costs and production energy consumption. (4) The preparation process is simple and highly operable: conventional vacuum brazing equipment is used, the steps are clear, the solder ratio and process parameters are easy to control, no special complex equipment is required, it is suitable for large-scale production, reduces production costs, and can meet the batch demand in the semiconductor manufacturing field; (5) Wide adaptability: The diamond arrangement density, double-layer solder thickness and bottom solder modification composition can be adjusted according to the dressing requirements of different CMP polishing pads to adapt to the dressing of different types of polishing pads. It is highly practical and can be widely used in CMP processes for semiconductor manufacturing and precision component processing. Attached Figure Description

[0024] Figure 1 This is a cross-sectional structural diagram of the brazed diamond disc of the present invention, wherein 1 is a diamond abrasive grain, 2 is an upper wear-resistant solder layer, 3 is a lower toughness solder layer, and 4 is the substrate. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and not intended to limit the invention.

[0026] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0027] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0028] The singular form includes the plural objects of discussion unless the context clearly indicates otherwise. "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event occurs and the possibility that the event does not occur.

[0029] The approximate terms used in the specification and claims modify quantities to indicate that the invention is not limited to that specific quantity, but also includes acceptable modifications close to that quantity that do not alter the relevant essential function. In some instances, approximate terms may correspond to the precision of the instrument measuring the value. In this specification and claims, scope definitions can be combined and / or interchanged, unless otherwise stated, these scopes include all subscopes contained therein.

[0030] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0031] Furthermore, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., described below refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0032] Example 1 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing comprises a stainless steel substrate, micron-sized diamond abrasive grains, and a double-layer solder structure, wherein: The bottom tough solder layer is based on BNi-2 nickel-based solder, with 1 wt% electrolytic copper powder (3 μm particle size) added, and the B content and Si content are adjusted to 2.8 wt%, the silicon / boron molar ratio is ≈1.2, and the solder layer thickness is 80 μm. Upper wear-resistant solder layer: BNi-2 standard nickel-based solder (Cr 7wt%, Si 3wt%, B 3wt%, Fe 3wt%, Ni balance), solder layer thickness 40μm; Diamond abrasive grains: 300μm in diameter, roughened by nitric acid and treated at 450℃, with an embedding depth of 120μm and a density of 400 grains / cm², suitable for the routine finishing needs of semiconductor wafer CMP polishing pads.

[0033] The above-mentioned method for preparing a brazed diamond disc includes the following steps: (1) Pretreatment of the substrate: Select a stainless steel substrate, grind it to Ra=0.6μm, soak it in sodium hydroxide solution (75℃) for 35min to remove oil, soak it in dilute hydrochloric acid for 12min to remove rust, ultrasonically clean it with deionized water until neutral, and vacuum dry it at 85℃. (2) Solder preparation: Underlying tough solder: Take BNi-2 powder, add 1wt% electrolytic copper powder, add anhydrous ethanol and ultrasonically disperse for 18 minutes to prepare solder slurry; Upper layer wear-resistant solder: Take BNi-2 standard powder, add 4wt% phenolic resin liquid and anhydrous ethanol, and mix to prepare solder slurry; (3) Diamond pretreatment: 300μm diamond abrasive grains were roughened with nitric acid solution (80℃) for 25min, treated at 450℃ for 30min, and cooled for later use; (4) Solder coating and diamond arrangement: Apply the bottom layer of solder paste to the substrate surface and dry at 85°C for 12 minutes; arrange diamond abrasive grains evenly and then apply the top layer of solder paste. (5) Vacuum brazing: Place in a vacuum brazing furnace, heat to 1030℃ at 6℃ / min, and hold for 20min; (6) Post-weld treatment: Cool down to room temperature at 4℃ / min, perform diffusion annealing at 900℃ for 2 hours, grind and polish to remove excess solder, and obtain the finished product.

[0034] The brazed diamond disc prepared in this embodiment is used for the finishing of CMP polishing pads for semiconductor wafers. Tests show that the diamond holding force is 42% higher than that of traditional single BNi-2 solder diamond discs. No diamond falls off after 100 hours of continuous finishing of the polishing pad. No scratches or defects are found during the subsequent wafer polishing process. The wafer pass rate is increased to over 99.5%, and the service life of the diamond disc is extended by 45%.

[0035] Appendix Figure 1 The substrate is made of stainless steel or nickel-based high-temperature alloy. Its surface is tightly bonded with a bottom tough solder layer. The bottom tough solder layer is covered with an upper wear-resistant solder layer, and the thickness of the upper wear-resistant solder layer is about 1 / 2 of the bottom tough solder layer. The diamond abrasive grains are embedded in the double-layer solder structure, with an embedding depth of 1 / 3 to 1 / 2 of their own grain diameter. The upper wear-resistant solder layer covers the exposed bottom of the diamond abrasive grains, forming a double holding structure of "bottom layer fixing and upper layer protection". This clearly shows the connection relationship of each component and is adapted to the mechanical requirements of CMP polishing pad dressing.

[0036] In step (5), the product is placed in a vacuum brazing furnace and heated to 1010-1080°C at a heating rate of 5-8°C / min, and held for 15-30 minutes. The performance of the resulting product is comparable to that of the finished product in Example 1. In step (6), the product is cooled to room temperature and subjected to diffusion annealing treatment at a cooling rate of 3-5°C / min. The workpiece is then placed in a heat treatment furnace at 880-920°C for diffusion annealing treatment for 1.5-2.5 hours. The performance of the resulting product is also comparable to that of the finished product in Example 1.

[0037] Example 2 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing comprises a nickel-based superalloy substrate, micron-sized diamond abrasive grains, and a double-layer solder structure, wherein: The bottom tough solder layer is based on BNi-2 nickel-based solder, with 3wt% cobalt powder (particle size 2μm) and 0.2wt% niobium powder added. The B content is adjusted to 2.5wt%, the Si content to 2.5wt%, the silicon / boron molar ratio is ≈1.2, and the solder layer thickness is 80μm. Upper wear-resistant solder layer: BNi-2 standard nickel-based solder is used, and the solder layer thickness is 40μm; Diamond abrasive grains: 200μm in diameter, roughened by nitric acid and treated at 500℃, with an embedding depth of 90μm and a density of 900 grains / cm², suitable for the dressing needs of high-precision semiconductor wafer CMP polishing pads.

[0038] The preparation method of the above-mentioned brazed diamond disk is the same as in Example 1, with the corresponding parameters adjusted: cobalt powder and niobium powder are added to the bottom solder, the brazing temperature is 1050℃, and the holding time is 25min. The remaining steps are the same as in Example 1.

[0039] The brazed diamond disc prepared in this embodiment is used for high-precision semiconductor wafer CMP polishing pad dressing. Tests show that the diamond holding force is 50% higher than that of traditional single BNi-2 solder diamond discs. No diamond falls off after 80 hours of continuous dressing of the polishing pad. The subsequent wafer polishing surface roughness Ra≤0.1μm, with no scratches or defects, and the service life of the diamond disc is extended by 50%.

[0040] Comparative Example 1 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing, unlike Example 1, does not include an upper wear-resistant solder layer. It is used for high-precision semiconductor wafer CMP polishing pad dressing. After testing, diamond detachment occurred 65 hours after the brazed diamond disc dressed the wafer CMP polishing pad.

[0041] Comparative Example 2 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad finishing differs from Example 1 in that step (5) vacuum brazing is as follows: Place it in a vacuum brazing furnace and heat it to 1030℃ at a rate of 10℃ / min, then hold it at that temperature for 20 minutes.

[0042] Used for high-precision semiconductor wafer CMP polishing pad dressing, tests showed that diamonds fell off after 90 hours of brazing diamond discs to dress the wafer CMP polishing pad.

[0043] Comparative Example 3 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad finishing differs from Example 1 in that step (5) vacuum brazing is as follows: Place it in a vacuum brazing furnace and heat it to 1030℃ at a rate of 3℃ / min, then hold it for 20 minutes.

[0044] Used for high-precision semiconductor wafer CMP polishing pad repair, tests showed that diamonds fell off after 95 hours of repairing the wafer CMP polishing pad with brazed diamond discs.

[0045] Comparative Example 4 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad finishing differs from Example 1 in that the post-soldering treatment in step (6) is as follows: The temperature was lowered to room temperature at 8℃ / min, and then diffused at 900℃ for 2 hours. Excess solder was removed by grinding and polishing to obtain the finished product.

[0046] Used for high-precision semiconductor wafer CMP polishing pad repair, tests showed that diamonds fell off after 75 hours of repairing the wafer CMP polishing pad with brazed diamond discs.

[0047] Comparative Example 5 A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad finishing differs from Example 1 in that the post-soldering treatment in step (6) is as follows: The temperature was lowered to room temperature at 1℃ / min, and then diffused at 900℃ for 2 hours. Excess solder was removed by grinding and polishing to obtain the finished product.

[0048] Used for high-precision semiconductor wafer CMP polishing pad repair, tests showed that diamonds fell off after 85 hours of repairing the wafer CMP polishing pad with brazed diamond discs.

[0049] Those skilled in the art will readily understand that the above description is only a part of the embodiments of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing, characterized in that, The high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing includes a substrate, diamond abrasive grains, and a double-layer solder structure for connecting the diamond abrasive grains and the substrate. The double-layer solder structure consists of a bottom tough solder layer and an upper wear-resistant solder layer. The diamond abrasive grains are partially embedded in the double-layer solder structure to a depth of 1 / 3 to 1 / 2 of the diamond abrasive grain diameter. The bottom tough solder layer is tightly bonded to the substrate, and the upper wear-resistant solder layer covers the exposed bottom portion of the diamond abrasive grains. The underlying toughness solder layer is a modified nickel-based solder with added copper powder or cobalt powder. The modified nickel-based solder uses BNi-2 nickel-based solder as the base, with 1-3 wt% electrolytic copper powder or 2-5 wt% cobalt powder added. The boron content and silicon content in the BNi-2 nickel-based solder are adjusted to 2.5-3.0 wt% and 2.5-3.0 wt% respectively, so that the silicon / boron molar ratio is 1.0-1.

4. An additional 0.1-0.5 wt% niobium powder is added to the underlying toughness solder layer.

2. The high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing according to claim 1, characterized in that, The upper wear-resistant solder layer is a high wear-resistant nickel-based solder, using BNi-2 standard nickel-based solder.

3. The method for preparing the high-holding-force, anti-detachment brazed diamond disk for CMP polishing pad dressing according to any one of claims 1-2, characterized in that, The method includes the following steps: (1) Substrate pretreatment: Select stainless steel or nickel-based alloy as the substrate, and perform grinding, degreasing and rust removal on the substrate surface to ensure the reliability of the bonding between the substrate and the solder layer; (2) Solder preparation: ① Preparation of the bottom toughness solder: Take BNi-2 nickel-based solder powder, add 1~3wt% electrolytic copper powder or 2~5wt% cobalt powder in proportion, and add 0.1~0.5wt% niobium powder to improve toughness. After mixing evenly, add an appropriate amount of anhydrous ethanol as a dispersant, and ultrasonically disperse to form a uniform solder slurry, ensuring that the modified elements are evenly distributed and improving the consistency of solder toughness. ② Preparation of upper layer wear-resistant solder: Take BNi-2 standard nickel-based solder powder, add anhydrous ethanol and binder, mix evenly to form solder slurry. The amount of binder added is 3~5% of the mass of solder powder, which is used to ensure the formability of solder layer and avoid peeling and cracking during the coating process. (3) Diamond pretreatment: Select hexagonal single-crystal diamond abrasive grains to remove surface oxides and adsorbates, and set aside for later use; (4) Solder coating and diamond arrangement: On the pretreated substrate surface, the bottom tough solder paste is coated by scraping and then dried to ensure the solder layer is formed. The pretreated diamond abrasive grains are evenly distributed on the surface of the bottom tough solder layer. The embedding depth of the diamond abrasive grains is controlled to be 1 / 3 to 1 / 2 of their grain size. The distribution density is adjusted according to the dressing requirements of the CMP polishing pad, taking into account both dressing efficiency and diamond holding stability. Apply an upper layer of wear-resistant solder paste to the bottom of the exposed part of the diamond abrasive grain and the surface of the bottom tough solder layer to ensure that the upper layer of solder covers the bottom of the diamond abrasive grain and does not obstruct the dressing surface of the diamond abrasive grain, thus ensuring the dressing effect of the polishing pad. (5) Vacuum brazing: The substrate coated with solder and diamond abrasive grains are placed in a vacuum brazing furnace so that the double-layer solder can be fully melted and react with the substrate and diamond abrasive grains to form a strong metallurgical bond, further enhancing the diamond holding force; (6) Post-weld treatment: After brazing, cool to room temperature and perform diffusion annealing to further eliminate the hard and brittle phase at the grain boundaries and improve the toughness and bonding strength of the solder layer; finally, grind and polish the surface of the workpiece to remove excess solder and obtain the finished brazed diamond disc, ensuring that the surface of the diamond disc is flat and can meet the high precision requirements of CMP polishing pad dressing.

4. The method for preparing a high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing according to claim 3, characterized in that, The grinding, degreasing, and rust removal processes involve grinding until the surface roughness Ra ≤ 0.8 μm, degreasing using sodium hydroxide solution, soaking at 70-80℃ for 30-40 minutes, and rust removal using dilute hydrochloric acid for 10-15 minutes. After treatment, the surfaces are ultrasonically cleaned with deionized water until neutral, and then vacuum dried at 80-90℃ for later use.

5. The method for preparing a high-holding-force, anti-detachment brazed diamond disk for CMP polishing pad dressing according to claim 3, characterized in that, The removal of surface oxides and adsorbates involves roughening the surface with nitric acid solution at 75-85°C for 20-30 minutes to remove surface oxides, followed by high-temperature treatment at 400-500°C for 25-35 minutes to remove surface adsorbates, and then cooling.

6. The method for preparing a high-holding-force, anti-detachment brazed diamond disk for CMP polishing pad dressing according to claim 3, characterized in that, In step (4), the coating thickness of the bottom tough solder slurry is controlled to be 1 / 3 to 1 / 2 of the diamond particle size; in step (4), drying is to place the coated material in an oven at 80 to 90 degrees Celsius for 10 to 15 minutes to remove the dispersant and moisture; in step (4), the coating thickness of the top wear-resistant solder slurry is controlled to be 1 / 3 to 1 / 2 of the thickness of the bottom tough solder slurry.

7. The method for preparing a high-holding-force, anti-detachment brazed diamond disc for CMP polishing pad dressing according to claim 3, characterized in that, In step (5), the sample is placed in a vacuum brazing furnace and heated to 1010-1080°C at a heating rate of 5-8°C / min, and held for 15-30 minutes.

8. The method for preparing a high-holding-force, anti-detachment brazed diamond disk for CMP polishing pad dressing according to claim 3, characterized in that, In step (6), the workpiece is cooled to room temperature and then subjected to diffusion annealing at a cooling rate of 3~5℃ / min. The workpiece is then placed in a heat treatment furnace at 880~920℃ for 1.5~2.5h diffusion annealing.

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