Cutting process of ultra-small size high-purity alumina crystal grains and application thereof

Abstract

The present application relates to the technical field of semiconductor, especially to the IPC H01L field, more particularly to a cutting process of ultra-small size high-purity alumina crystal grains and application thereof. The present application cuts the ultra-small size high-purity alumina crystal grains through eight steps of pretreatment process, smearing adhesive, bonding, pasting cutting film, cutting, pasting protective film, removing adhesive and packaging, and has high process precision, convenient and feasible operation, can cut small size crystal grains (less than 0.5mm in edge length), the small size crystal grains obtained by cutting have regular shape, no cracking, the yield is as high as more than 99%, and the packaging is convenient, low in cost, and suitable for application in the fields of semiconductor, printed circuit board manufacturing and the like.

Description

Technical Field

[0001] This invention relates to the field of semiconductor technology, particularly to the field of IPC H01L, and more specifically, to a cutting process for ultra-small high-purity alumina grains and its application. Background Technology

[0002] In recent years, the dimensions of thin-film devices have become increasingly smaller. Traditional abrasive wheel cutting methods can still meet the requirements for softer ceramic substrates such as silicon wafers, aluminum nitride, and ferrite. However, for ultrahard materials such as corundum, sapphire, and alumina, cutting small-sized grains (side length less than 0.5mm) presents many problems, such as: 1. Cutting kerf deviation, which can severely damage the circuitry; 2. Trapezoidal grain shape, resulting in substandard appearance and excessive dimensional deviation; 3. Severe grain breakage, directly affecting the yield. Although laser cutting can meet basic slitting requirements, it can cause adverse effects such as scorching and heat accumulation that affects electrical performance.

[0003] In the prior art, the patent document with application publication number CN105965708A discloses a method and apparatus for cutting semiconductor chips. By using water or soapy water as the cutting fluid and in conjunction with a pouring device for the cutting fluid, the product quality can be improved. However, when cutting small-sized chips, the addition of the cutting fluid will actually reduce the friction on the wafer surface and cause the cutting path to deviate.

[0004] The patent application with publication number CN102468233B discloses a method for manufacturing semiconductor wafers by laser cutting. This method can effectively avoid the etching and undercutting phenomenon that occurs in subsequent manufacturing processes after laser cutting of components on semiconductor chips. However, the laser may burn small-sized particles, affecting their electrical performance. Summary of the Invention

[0005] To address the aforementioned problems, the first aspect of this invention provides a cutting process for ultra-small high-purity alumina grains, the process flow diagram of which is shown below. Figure 1 As shown, it includes the following steps:

[0006] S1. Pre-treatment process: Clean the padding material and substrate with water and bake them dry for later use;

[0007] S2. Apply adhesive: After heating both the pad and the substrate to 120-140℃, apply adhesive evenly to side A of the pad and side B of the substrate.

[0008] S3. Adhesion: Closely adhere side A of the pad material and side B of the substrate to form composition one. Place composition one at room temperature until the pad material and the substrate are firmly bonded.

[0009] S4. Apply the cutting film: Apply side B of the padding material in Composition 1 to the cutting film;

[0010] S5. Cutting: Place the substrate in Composition 1 with side A facing up on a cutting machine to cut the substrate into multiple grains;

[0011] S6. Apply protective film: After cutting, apply a protective film to side A of the substrate to obtain composition two;

[0012] S7. Remove adhesive: After heating composition two, peel off the protective film and substrate, and immerse the protective film and substrate in a solvent to obtain composition three;

[0013] S8. Packaging: Pick out the cut crystals from the assembly three.

[0014] The structural diagram of the first composition is as follows: Figure 2 As shown.

[0015] The A side of the pad is the bonding surface with the substrate; the B side of the pad is the contact surface with the cutting machine; the B side of the substrate is the bonding surface with the pad; and the A side of the substrate is the cutting surface.

[0016] In some preferred embodiments, in step S2, cutting wax is evenly applied to both side A of the pad and side B of the substrate and then tightly adhered. This helps improve the flatness between the pad and the substrate, thereby improving the quality of the cut grains. Poor flatness of the alumina substrate affects the flatness between the substrate and the pad, thus impacting cutting efficiency and quality. Furthermore, air bubbles between the substrate and the pad, with bubbles larger than the grain size, can cause the substrate to easily fly away from areas with bubbles, making collection difficult and affecting the final product yield and profitability.

[0017] Preferably, the pad material is one or more of ceramic wafers and silicon wafers.

[0018] Preferably, the ceramic sheet has a Rockwell hardness of 75-95 HRA, a flexural strength of 250-350 MPa, and a coefficient of thermal expansion of 6.0-8.0 × 10⁻⁶. -6 m / m·K; More preferably, the Rockwell hardness of the padding material is 85 HRA, the flexural strength is 290 MPa, and the coefficient of thermal expansion is 7.2 × 10⁻⁶ m / m·K. -6 m / m·K.

[0019] In some preferred embodiments, the ceramic blank is purchased from wear-resistant ceramic lining YCH002 manufactured by Zibo Yingchi Ceramic New Materials Co., Ltd.

[0020] Preferably, the substrate is an alumina substrate.

[0021] Preferably, the alumina substrate is made of one or more of the following materials: 75% ceramic alumina, 92% ceramic alumina, 95% ceramic alumina, 96% ceramic alumina, 97% ceramic alumina, 99% ceramic alumina, 995% ceramic alumina, and 997% ceramic alumina; more preferably, it is 99% ceramic alumina.

[0022] Preferably, the thickness of the substrate is <0.5mm; more preferably, the thickness of the substrate is ≤0.3mm.

[0023] Alumina substrates, especially 99% ceramic alumina substrates, are used in thin-film devices to replace polymer materials as circuit board substrates. They have good heat resistance and high stability, but their hardness is high, second only to diamond. Therefore, when cutting them into ultra-fine particles (particle area ≤ 0.5 × 0.5 mm2), using commercially available cutting films, such as highly viscous cutting films and PET cutting films with hard substrates, results in unsatisfactory grain quality. This is because the bottom area of ​​the ultra-fine particles is too small, and the strength of commercially available cutting films is insufficient, causing the ultra-fine grains to be difficult to stabilize and to shift, and there is even a risk of scratching the surface circuit of the grains.

[0024] The applicant discovered that using ceramic or silicon wafers as backing materials improves yield. This is likely because ceramic or silicon wafers, as backing materials, have high hardness and flatness, allowing ultrafine grains to be fixed firmly during cutting without shifting. In particular, using ceramic wafers with a Rockwell hardness of 75-95 HRA, flexural strength of 250-350 MPa, and coefficient of thermal expansion of 6.0-8.0 × 10⁻⁶ m / m·K not only avoids large variations in grain size caused by the softness and deformation of the backing material during processing, but also minimizes thermal expansion when heated and bonded to the substrate, ensuring a tight bond and preventing temperature changes from affecting grain quality. However, ordinary adhesives either have low bonding strength, failing to firmly bond the substrate to the substrate, or even if they have good bonding ability, removing the adhesive and separating the substrate from the substrate is extremely difficult, and forced separation can damage the cut grains.

[0025] Preferably, the adhesive is one or more of cutting wax, UV adhesive, hot melt adhesive, and pressure-sensitive adhesive; more preferably, it is cutting wax.

[0026] Preferably, the cutting wax is one or more of rosin resin, terpene resin, paraffin wax, polyethylene wax, and microcrystalline wax; more preferably, it is rosin resin.

[0027] Preferably, the rosin resin has a softening point of 70-90℃, an acid value of 130-180mg KOH / g, and ethanol-insoluble matter ≤0.05wt%; more preferably, the hydrogenated rosin resin has a softening point of 76℃, an acid value of 166mg KOH / g, and ethanol-insoluble matter ≤0.03wt%.

[0028] In some preferred embodiments, the rosin resin is purchased from resin rosin produced by Xiamen Haiju Chemical Co., Ltd.

[0029] The applicant unexpectedly discovered that using rosin resin with a softening point of 70-90℃, an acid value of 130-180mg KOH / g, and ethanol-insoluble matter ≤0.05wt% as cutting wax not only ensured strong adhesion between the substrate and the backing material but also facilitated easy removal without leaving residue on the grains, thus guaranteeing grain quality. This is likely due to the specific viscosity of the rosin resin, its solid state at room temperature which stabilizes the substrate on the backing material, and its softening and melting at certain temperatures. Furthermore, its low ethanol insolubility allows for the removal of residual cutting wax from the grain surface through subsequent immersion in ethanol. This ensures grain size while protecting the surface circuitry, significantly improving the yield rate of the process.

[0030] Preferably, the specific process steps of step S5 are as follows: place the substrate of composition one with side A facing up on the cutting machine, install the cutting ring into the cutting machine, select the program, confirm the cutting mark and cutting size, run the cutting program, and cut the substrate to obtain multiple grains.

[0031] Preferably, the cutting ring is a diamond grinding wheel cutter with a blade width of 0.05-0.2 mm.

[0032] In some preferred solutions, a diamond grinding wheel with a blade width of 0.05-0.2 mm is used as the cutting ring. This allows for rapid cutting of the substrate while avoiding damage to the circuitry on the substrate surface. Grinding wheels with excessively narrow blades exert high pressure and are prone to breakage during substrate cutting. Since the required grain size is generally 0.5 × 0.5 mm² or smaller, using grinding wheels with excessively long blades can easily damage the circuitry on the substrate surface. Even if the dimensions are within acceptable limits, such grinding wheels cannot be used in thin-film devices.

[0033] Preferably, in the cutting process of step S5, the cutting depth is greater than the wafer thickness and less than the wafer thickness plus the pad material thickness.

[0034] In some preferred embodiments, in the cutting process of step S5, the cutting depth is greater than the wafer thickness but less than the wafer thickness plus the pad material thickness. This can reduce subsequent processing steps while ensuring the quality of the wafer. During the cutting process, if the cutting depth is not carefully considered, the wafer may not be completely cut into wafers, or the cutting may be too deep, completely cutting through the pad material. This affects both wafer quality and the dimensional accuracy of the wafer, as the pad material remains attached to the substrate after complete cutting. Furthermore, the pad material is strong, and subsequent processing after complete breakage is time-consuming and laborious, making piece-by-piece peeling simpler and easier.

[0035] Preferably, the adhesive force of the protective film in step S6 is 1-3 N / 20 mm; more preferably, it is 2 N / 20 mm.

[0036] In some preferred embodiments, the protective film is purchased from Nitto Corporation's SPV-224SRB blue film.

[0037] Preferably, in step S7, the heating process is as follows: the second composition is placed on a hot plate and heated to 70-90°C, and maintained for 30-60 minutes.

[0038] Preferably, the solvent in step S7 is one or more of water, ethanol, acetone, ethyl acetate, and methanol; more preferably, it is ethanol.

[0039] Preferably, the soaking time in step S7 is 10-30 minutes.

[0040] The second aspect of this invention provides an application of the cutting process for the ultra-small high-purity alumina grains, which can be applied to fields such as semiconductors and printed circuit board manufacturing.

[0041] Beneficial effects:

[0042] 1. This invention selects materials with a Rockwell hardness of 75-95 HRA, a flexural strength of 250-350 MPa, and a coefficient of thermal expansion of 6.0-8.0 × 10⁻⁶. -6 Using ceramic blanks with a density of m / m·K as padding material can improve the yield rate.

[0043] 2. This invention uses rosin resin with a softening point of 70-90℃, an acid value of 130-180mg KOH / g, and ethanol insoluble matter ≤0.05wt% as cutting wax. This wax can firmly bond the substrate and the pad material while being easy to remove and leaving no residue on the grains, thus ensuring the quality of the grains.

[0044] 3. This application uses a diamond grinding wheel with a blade width of 0.05-0.2mm as the cutting ring, which can quickly cut the substrate while avoiding damage to the circuitry on the substrate surface.

[0045] 4. By controlling the depth of cut in step S5, this application can reduce subsequent processing steps while ensuring grain quality.

[0046] 5. This invention uses a specific cutting wax as an adhesive to bond the substrate and the pad material, which ensures sufficient adhesion between the two. On the other hand, it uses a specific ceramic bare sheet as the pad material, which has sufficient strength and will not cause swaying when cutting the grains.

[0047] 6. This application utilizes a specific cutting process with high precision and convenient operation. It can cut small-sized grains (side length less than 0.5mm), and the resulting small-sized grains are regular in shape, without cracking, with a yield of over 99%. Furthermore, the packaging is convenient and cost-effective, making it suitable for applications in semiconductor, printed circuit board manufacturing, and other fields. Attached Figure Description

[0048] Figure 1 This is a flowchart of the cutting process for the ultra-small high-purity alumina grains described in this application;

[0049] Figure 2 This is a structural diagram of composition one in this application;

[0050] In the figure, 1 is the substrate; 2 is the padding material. Detailed Implementation

[0051] Example

[0052] Example 1

[0053] Example 1 provides a cutting process for ultra-small high-purity alumina grains, including the following steps:

[0054] S1. Pre-treatment process: Clean the padding material and substrate with water and bake them dry for later use;

[0055] S2. Apply adhesive: After heating both the pad and the substrate to 130°C, apply adhesive evenly to side A of the pad and side B of the substrate.

[0056] S3. Adhesion: Closely adhere side A of the pad material and side B of the substrate to form composition one. Place composition one at room temperature until the pad material and the substrate are firmly bonded.

[0057] S4. Apply the cutting film: Apply side B of the padding material in Composition 1 to the cutting film;

[0058] S5. Cutting: Place the substrate in Composition 1 with side A facing up on a cutting machine to cut the substrate into multiple grains;

[0059] S6. Apply protective film: After cutting, apply a protective film to side A of the substrate to obtain composition two;

[0060] S7. Remove adhesive: After heating composition two, peel off the protective film and substrate, and immerse the protective film and substrate in a solvent to obtain composition three;

[0061] S8. Packaging: Pick out the cut crystals from the assembly three.

[0062] The pad material is made of ceramic sheet.

[0063] The padding material has a Rockwell hardness of 85 HRA, a flexural strength of 290 MPa, and a coefficient of thermal expansion of 7.2 × 10⁻⁶. -6 m / m·K.

[0064] The ceramic blank was purchased from wear-resistant ceramic lining YCH002 produced by Zibo Yingchi Ceramic New Materials Co., Ltd.

[0065] The substrate is an alumina substrate.

[0066] The alumina substrate is made of 99% ceramic alumina.

[0067] The thickness of the substrate is 0.3 mm.

[0068] The substrate was purchased from Suzhou Huabo Electronic Technology Co., Ltd.

[0069] The adhesive is cutting wax.

[0070] The cutting wax is rosin resin.

[0071] The hydrogenated rosin resin has a softening point of 76°C, an acid value of 166 mg KOH / g, and ethanol-insoluble matter ≤0.03 wt%.

[0072] The rosin resin was purchased from rosin produced by Xiamen Haiju Chemical Co., Ltd.

[0073] The specific process steps of step S5 are as follows: place the substrate of composition one with side A facing up on the cutting machine, install the cutting ring into the cutting machine, select the program, confirm the cutting mark and cutting size, run the cutting program, and cut the substrate to obtain multiple grains.

[0074] The cutting size is 0.1 × 0.1 mm. 2 .

[0075] The cutting ring is a diamond grinding wheel cutter; the cutter width is 0.1 mm.

[0076] In the cutting process of step S5, the depth of cut is 0.4 mm.

[0077] The adhesive force of the protective film in step S6 is 2N / 20mm.

[0078] The protective film was purchased from Nitto Corporation's SPV-224SRB blue film.

[0079] In step S7, the heating process is as follows: the second composition is placed on a hot plate and heated to 80°C, and held for 45 minutes.

[0080] The solvent in step S7 is ethanol.

[0081] The soaking time in step S7 is 15 minutes.

[0082] The second aspect of this invention provides an application of the cutting process for the ultra-small high-purity alumina grains, which can be applied to the semiconductor field.

[0083] Example 2

[0084] Example 2 provides a cutting process for ultra-small high-purity alumina grains. The specific implementation method is the same as in Example 1, except that:

[0085] Includes the following steps:

[0086] S1. Pre-treatment process: Clean the padding material and substrate with water and bake them dry for later use;

[0087] S2. Apply adhesive: After heating both the pad and the substrate to 120°C, apply adhesive evenly to side A of the pad and side B of the substrate.

[0088] S3. Adhesion: Closely adhere side A of the pad material and side B of the substrate to form composition one. Place composition one at room temperature until the pad material and the substrate are firmly bonded.

[0089] S4. Apply the cutting film: Apply side B of the padding material in Composition 1 to the cutting film;

[0090] S5. Cutting: Place the substrate in Composition 1 with side A facing up on a cutting machine to cut the substrate into multiple grains;

[0091] S6. Apply protective film: After cutting, apply a protective film to side A of the substrate to obtain composition two;

[0092] S7. Remove adhesive: After heating composition two, peel off the protective film and substrate, and immerse the protective film and substrate in a solvent to obtain composition three;

[0093] S8. Packaging: Pick out the cut crystals from the assembly three.

[0094] The cutting ring is a diamond grinding wheel cutter; the cutter width is 0.05mm.

[0095] In step S7, the heating process is as follows: the second composition is placed on a hot plate and heated to 70°C, and held for 60 minutes.

[0096] The soaking time in step S7 is 10 minutes.

[0097] Example 3

[0098] Example 3 provides a cutting process for ultra-small high-purity alumina grains. The specific implementation method is the same as in Example 1, except that:

[0099] Includes the following steps:

[0100] S1. Pre-treatment process: Clean the padding material and substrate with water and bake them dry for later use;

[0101] S2. Apply adhesive: After heating both the pad and the substrate to 140°C, apply adhesive evenly to side A of the pad and side B of the substrate.

[0102] S3. Adhesion: Closely adhere side A of the pad material and side B of the substrate to form composition one. Place composition one at room temperature until the pad material and the substrate are firmly bonded.

[0103] S4. Apply the cutting film: Apply side B of the padding material in Composition 1 to the cutting film;

[0104] S5. Cutting: Place the substrate in Composition 1 with side A facing up on a cutting machine to cut the substrate into multiple grains;

[0105] S6. Apply protective film: After cutting, apply a protective film to side A of the substrate to obtain composition two;

[0106] S7. Remove adhesive: After heating composition two, peel off the protective film and substrate, and immerse the protective film and substrate in a solvent to obtain composition three;

[0107] S8. Packaging: Pick out the cut crystals from the assembly three.

[0108] The cutting ring is a diamond grinding wheel cutter; the cutter width is 0.2mm.

[0109] In step S7, the heating process is as follows: the second composition is placed on a hot plate and heated to 90°C, and held for 30 minutes.

[0110] The soaking time in step S7 is 30 minutes.

[0111] Comparative Example 1

[0112] Comparative Example 1 provides a high-precision beryllium copper wire and its preparation method, with the specific implementation method being the same as in Example 1. The difference is that the pad material is a PET film.

[0113] The PET film was purchased from Dongguan Lizhiyuan Plastics Co., Ltd.

[0114] Comparative Example 2

[0115] Comparative Example 2 provides a high-precision beryllium copper wire and its preparation method, with the specific implementation method being the same as in Example 1. The difference is that the adhesive used is a UV adhesive.

[0116] The UV adhesive was purchased from Dongguan Zuoyan Electronic Materials Co., Ltd. as wafer dicing UV adhesive ZY-3620.

[0117] Comparative Example 3

[0118] Comparative Example 3 provides a high-precision beryllium copper wire and its preparation method, with the specific implementation method being the same as in Example 1. The difference is that the cutting ring is a diamond grinding wheel cutter with a blade width of 0.3 mm.

[0119] Performance testing methods

[0120] Yield test

[0121] The grains prepared by the processes of Examples 1-3 and Comparative Examples 1-3 were placed under a microscope and visually inspected to check whether their dimensional accuracy was up to standard and whether there were scratches on the grains. If the dimensional accuracy and the grain surface were both up to standard, the grains were considered to be of qualified quality. The yield (%) = number of qualified grains / total number of grains * 100%, and the results were recorded in Table 1.

[0122] Table 1

[0123]

[0124]

Claims

1. A cutting process for ultra-small high-purity alumina grains, characterized in that, Includes the following steps: S1. Pre-treatment process: Clean the padding material and substrate with water and bake them dry for later use; S2. Apply adhesive: After heating both the pad and the substrate to 120-140℃, apply adhesive evenly to side A of the pad and side B of the substrate. S3. Adhesion: Closely adhere side A of the pad material and side B of the substrate to form composition one. Place composition one at room temperature until the pad material and the substrate are firmly bonded. S4. Apply the cutting film: Apply side B of the padding material in Composition 1 to the cutting film; S5. Cutting: Place the substrate in Composition 1 with side A facing up on a cutting machine to cut the substrate into multiple grains; S6. Apply protective film: After cutting, apply a protective film to side A of the substrate to obtain composition two; S7. Remove adhesive: After heating composition two, peel off the protective film and substrate, and immerse the protective film and substrate in a solvent to obtain composition three; S8. Packaging: Pick out the cut crystals from the assembly three; The pad material is a bare ceramic sheet with a Rockwell hardness of 75-95 HRA, a flexural strength of 250-350 MPa, and a coefficient of thermal expansion of 6.0-8.0 × 10⁻⁶. -6 m / m·K.

2. The cutting process for ultra-small high-purity alumina grains according to claim 1, characterized in that, The substrate is an alumina substrate; the material of the alumina substrate is one or more of 75 ceramic alumina, 92 ceramic alumina, 95 ceramic alumina, 96 ceramic alumina, 97 ceramic alumina, 99 ceramic alumina, 995 ceramic alumina, and 997 ceramic alumina.

3. The cutting process for ultra-small high-purity alumina grains according to claim 1, characterized in that, The adhesive is one or more of cutting wax, UV adhesive, hot melt adhesive, and pressure-sensitive adhesive.

4. The cutting process for ultra-small high-purity alumina grains according to claim 3, characterized in that, The cutting wax is one or more of the following: rosin resin, terpene resin, paraffin wax, polyethylene wax, and microcrystalline wax.

5. The cutting process for ultra-small high-purity alumina grains according to claim 1, characterized in that, The specific process steps of step S5 are as follows: Place the substrate in composition one with side A facing up on the cutting machine, install the cutting ring into the cutting machine, select the program, confirm the cutting mark and cutting size, run the cutting program, and cut the substrate to obtain multiple grains. The cutting ring is a diamond grinding wheel cutter; the cutter width is 0.05-0.2mm.

6. The cutting process for ultra-small high-purity alumina grains according to claim 1, characterized in that, In step S7, the heating process is as follows: place the second composition on a hot plate and heat it to 70-90°C, and maintain it for 30-60 minutes.

7. The cutting process for ultra-small high-purity alumina grains according to claim 1, characterized in that, The solvent in step S7 is one or more of water, ethanol, acetone, ethyl acetate, and methanol.

8. An application of a cutting process for ultra-small high-purity alumina grains as described in any one of claims 1-7, characterized in that, It is used in the fields of semiconductor and printed circuit board manufacturing.

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