Preparation process of BR micro powder for semiconductor industry

Abstract

The application discloses a preparation process of BR micropowder for the semiconductor industry, adopts liquid nitrogen low-temperature crushing to reduce micro-powder cracks and agglomeration, carries out gravity sedimentation-gradient magnetic separation grading, cooperates with dilute nitric acid-hydrofluoric acid mixed acid liquid deep impurity removal, and then carries out vacuum high-temperature reduction treatment and argon plasma activation, and sequentially deposits SiN x The transition layer and the diamond film form a composite film, and finally, the BR micropowder product is obtained through vacuum annealing and airflow grading. The BR micropowder prepared by the application has high purity, low total amount of metal impurities, small particle size distribution deviation, significantly reduced surface roughness, uniform particle strength, can effectively reduce chip processing scratch, edge collapse and metal pollution risk, and meets the high-precision and high-cleanliness requirements of high-end semiconductor cutting, grinding and polishing.

Description

Technical Field

[0001] This invention relates to the field of diamond crushing technology, and more specifically to a preparation process for BR micro powder for the semiconductor industry. Background Technology

[0002] As the semiconductor industry rapidly advances towards higher precision and integration, chip cutting, grinding, and polishing processes place extremely high demands on processing accuracy, surface cleanliness, and control of surface damage layers. Traditional diamond micropowders are mostly general-purpose products with performance parameters lacking specificity, making them difficult to adapt to the unique processing needs of the semiconductor industry. BR micropowder, as a specialized micropowder produced after diamond crushing and grading, has become one of the core consumables in the precision machining of semiconductor chips due to its ultra-high hardness and excellent wear resistance. However, BR micropowder prepared using existing processes still has several problems, as detailed below: 1. Excessive impurity content: During the preparation process, metallic impurities (such as Fe, Ni, Co, Cu, etc.) and non-metallic impurities (such as graphite, amorphous carbon, silicates, etc.) are easily left behind. These impurities will cause chip surface contamination during semiconductor processing, trigger metal ion migration, and thus lead to semiconductor device failure, failing to meet the stringent requirements of the semiconductor industry for processing cleanliness. 2. Large fluctuations in particle strength: Fine-particle BR powder contains a high proportion of cracked and low-strength particles, which are prone to breakage during precision manufacturing, resulting in powder agglomerates. This leads to defects such as scratches and chipping on the chip surface, seriously affecting chip processing quality. 3. Mismatched surface characteristics: Existing BR powder has a high surface roughness and sharp particle edges. During precision grinding and polishing, it is easy to cause excessive damage to the semiconductor wafer surface, which cannot meet the processing requirements of ultra-smooth semiconductor surfaces.

[0003] In summary, the performance of BR micropowder prepared by existing processes is not good. Therefore, this invention is proposed. Summary of the Invention

[0004] The purpose of this invention is to provide a process for preparing BR micropowder for the semiconductor industry in order to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention specifically adopts the following technical solution: A process for preparing BR micropowder for the semiconductor industry includes the following steps: S1. Pre-treat diamond monomers to obtain primary BR micro powder; Furthermore, the specific method of S1 includes: Diamond monomers were crushed in a liquid nitrogen environment at -80~-40℃ to obtain crude BR powder. The crude BR powder was then coarsely classified to remove particles larger than 20μm and particles smaller than 1μm, resulting in primary BR powder.

[0006] The low-temperature brittleness of diamond is utilized to improve crushing efficiency while avoiding graphitization caused by high temperatures during crushing and thermal diffusion contamination from metallic impurities. To enhance the strength of BR micronized powder particles, an eccentric impact directional crushing method is employed, controlling the crushing force direction along the diamond cleavage plane to reduce the generation of microcracks within the particles.

[0007] Furthermore, the crushing speed is 2000~3500 r / min and the ball-to-material ratio is 5~8:1.

[0008] S2. The BR micro powder screened in the primary screening is prepared into a dispersion with a mass fraction of 5-10%. After the first classification by gravity sedimentation, cracked particles, weak particles and agglomerates are removed. Then, the BR micro powder intermediate is obtained by gradient magnetic separation. Furthermore, the gravity settling velocity is 8~12 mL / s, and the gradient selection intensities are 100 mT, 150 mT, and 200 mT respectively.

[0009] S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 25-40℃ for 20-30 minutes to remove non-magnetic metal impurities and silicate impurities. Then it is washed with deionized water until the pH is 7.0. Furthermore, the acidic mixture has a mass fraction of 2-5%, and the acidic mixture includes dilute nitric acid and hydrofluoric acid in a volume ratio of 2-4:1.

[0010] S4. The cleaned BR micro powder intermediate is subjected to gradient heating in a vacuum environment; then, the surface of the BR micro powder intermediate after gradient heating is treated with argon plasma, which not only removes surface adsorbed impurities and residual oxide layer, but also smooths out the sharp corners of the particles and reduces surface stress, providing a flat substrate for subsequent film deposition; then, a composite film is deposited on the surface of the BR micro powder intermediate. Furthermore, the gradient heating process specifically includes: First, the powder is held at 800℃ in a vacuum environment for 30 minutes to remove amorphous carbon impurities. Then, a mixed gas with a volume ratio of 1:5~8 is introduced, and the temperature is raised to 900~950℃ and held for 40~60 minutes to reduce oxygen impurities on the surface of the powder and further improve the purity. Finally, the powder is cooled to room temperature to inhibit graphitization on the surface of the powder, thereby improving the purity and stability of the diamond powder. The mixture includes hydrogen and argon.

[0011] Furthermore, specific methods for depositing composite films on the surface of BR micronized powder intermediates include: SiN was deposited on the surface of the BR micro powder intermediate after treatment with a first plasma at 180-220W for 10-15 minutes. x A transition layer is used to improve the adhesion of the subsequent passivation layer and prevent film detachment; then, after treatment with a second plasma at 150~250W for 15~25 min, the SiN... x A diamond film is deposited on the surface of the transition layer to obtain a composite film. This diamond film is a low-friction diamond-like film, which reduces the friction coefficient of the BR micron powder intermediate and reduces damage to the semiconductor wafer surface.

[0012] Furthermore, the first plasma comprises silane and nitrogen in a volume ratio of 1:3 to 5, and the second plasma comprises methane and hydrogen in a volume ratio of 2 to 3:1.

[0013] Furthermore, the thickness of the composite film is 5~10 nm.

[0014] S5. The BR micro powder intermediate with a composite film formed on its surface is vacuum annealed at 200~300℃ for 1~1.5h to eliminate residual stress on the surface of the micro powder and inside the film layer, further improve the stability of the film layer and prevent the film layer from falling off during subsequent use; then the BR micro powder product is obtained by air classification.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. By crushing diamond monomers in a liquid nitrogen environment of -80~-40℃, the low-temperature brittleness of diamond is fully utilized to effectively improve crushing efficiency, while avoiding diamond graphitization caused by high temperature during crushing and thermal diffusion pollution of metal impurities; combined with an eccentric impact directional crushing method, the crushing force direction is controlled along the diamond cleavage plane to reduce the generation of microcracks inside the particles and improve the strength of BR micro powder particles. 2. Gravity sedimentation is used for the first classification to effectively remove cracked particles, weak particles, and agglomerates from the initial BR micro powder. Then, a second classification is carried out by gradient magnetic separation with intensities of 100mT, 150mT, and 200mT, respectively, to obtain BR micro powder intermediates with initially improved purity. In the subsequent S3, a dilute nitric acid-hydrofluoric acid mixture with a mass fraction of 2-5% and a volume ratio of 2-4:1 is used for acid washing at 25-40℃ for 20-30 minutes to thoroughly remove non-magnetic metal impurities and silicate impurities. Then, it is washed with deionized water until pH=7.0 to further improve the cleanliness of the micro powder. 3. SiN deposition via first plasma x The transition layer significantly improves the adhesion of the subsequent passivation layer and prevents the film from peeling off; then, a second plasma is applied to SiN... xA diamond film is deposited on the surface of the transition layer to form a composite film with a thickness of 5~10nm, which effectively reduces the friction coefficient of BR micropowder and reduces its damage to the wafer surface during semiconductor wafer processing. Detailed Implementation

[0016] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The materials and instruments used in the following embodiments are all commercially available.

[0017] A process for preparing BR micropowder for the semiconductor industry includes the following steps: S1. Pre-treat diamond monomers to obtain primary BR micro powder; Furthermore, the specific methods of S1 include: Diamond monomers were crushed in a liquid nitrogen environment at -80~-40℃ to obtain crude BR powder. The crude BR powder was then coarsely classified to remove particles larger than 20μm and particles smaller than 1μm, resulting in primary BR powder.

[0018] Furthermore, the crushing speed is 2000~3500 r / min and the ball-to-material ratio is 5~8:1.

[0019] S2. The BR micro powder screened at the initial screening is prepared into a dispersion with a mass fraction of 5-10%. After the first classification by gravity sedimentation, the BR micro powder intermediate is obtained by gradient magnetic separation. S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 25~40℃ for 20~30 min, and then washed with deionized water. Furthermore, the mass fraction of the acidic mixture is 2-5%, and the acidic mixture includes dilute nitric acid and hydrofluoric acid in a volume ratio of 2-4:1.

[0020] S4. The cleaned BR micro powder intermediate is subjected to gradient heating in a vacuum environment, and then the surface of the BR micro powder intermediate after gradient heating is treated by argon plasma. Finally, a composite film is deposited on the surface of the BR micro powder intermediate. Furthermore, the gradient heating method specifically includes: First, hold the temperature in a vacuum environment at 800℃ for 30 minutes, then introduce a mixed gas with a volume ratio of 1:5~8, raise the temperature to 900~950℃, hold the temperature for 40~60 minutes, and finally cool to room temperature. The mixture includes hydrogen and argon.

[0021] Furthermore, specific methods for depositing composite films on the surface of BR micronized powder intermediates include: SiN was deposited on the surface of the BR micro powder intermediate after treatment with a first plasma at 180-220W for 10-15 minutes. x A transition layer is formed, followed by treatment with a second plasma at 150-250 W for 15-25 min, and then on SiN. x A diamond film is deposited on the surface of the transition layer to obtain a composite film.

[0022] Furthermore, the first plasma comprises silane and nitrogen in a volume ratio of 1:3 to 5, and the second plasma comprises methane and hydrogen in a volume ratio of 2 to 3:1.

[0023] Furthermore, the thickness of the composite film is 5~10nm.

[0024] S5. After vacuum annealing the BR micro powder intermediate with a composite film formed on its surface at 200~300℃ for 1~1.5h, the BR micro powder product is obtained by air classification.

[0025] The present invention will be further described below with reference to specific embodiments and comparative examples.

[0026] Example 1 This embodiment provides a process for preparing BR micropowder for the semiconductor industry, including the following steps: S1. Diamond monomers are crushed in a liquid nitrogen environment at -50℃ to obtain BR micro powder crude product. The BR micro powder crude product is coarsely classified to remove BR micro powder with a particle size greater than 20μm and a particle size less than 1μm, and then the primary BR micro powder is obtained. The crushing speed is 3000r / min and the ball-to-material ratio is 6:1. S2. The BR micro powder screened at the initial screening is prepared into a dispersion with a mass fraction of 8%. After the first classification by gravity sedimentation, the BR micro powder intermediate is obtained by gradient magnetic separation. S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 35°C for 25 minutes, and then washed with deionized water. The acidic mixture has a mass fraction of 3%, and the acidic mixture includes dilute nitric acid and hydrofluoric acid in a volume ratio of 3:1. S4. The cleaned BR micropowder intermediate is first held at 800℃ for 30 min in a vacuum environment, then a hydrogen-argon mixture with a volume ratio of 1:7 is introduced, the temperature is raised to 930℃, and held for 50 min. Finally, it is cooled to room temperature, and then the surface of the BR micropowder intermediate after gradient heating treatment is performed by argon plasma. After treatment with the first plasma at 200W for 13 min, SiN is deposited on the surface of the BR micropowder intermediate.x A transition layer was then formed, followed by treatment with a second plasma at 200 W for 20 min, and then applied to SiN. x A diamond film was deposited on the surface of the transition layer to obtain a 7nm thick composite film; The first plasma consists of silane and nitrogen in a volume ratio of 1:4, and the second plasma consists of methane and hydrogen in a volume ratio of 2.5:1. S5. After vacuum annealing the BR micro powder intermediate with a composite film formed on its surface at 250°C for 1.2 hours, the BR micro powder product is obtained by air classification.

[0027] Example 2 This embodiment provides a process for preparing BR micropowder for the semiconductor industry, including the following steps: S1. Diamond monomers are crushed in a liquid nitrogen environment at -80℃ to obtain BR micro powder crude product. The BR micro powder crude product is coarsely classified to remove BR micro powder with a particle size greater than 20μm and a particle size less than 1μm, and then the primary BR micro powder is obtained. The crushing speed is 2000r / min and the ball-to-material ratio is 5:1. S2. The BR micro powder screened at the initial screening is prepared into a dispersion with a mass fraction of 5%. After the first classification by gravity sedimentation, the BR micro powder intermediate is obtained by gradient magnetic separation. S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 25°C for 20 minutes, and then washed with deionized water. The acidic mixture has a mass fraction of 2%, and the acidic mixture includes dilute nitric acid and hydrofluoric acid in a volume ratio of 2:1. S4. The cleaned BR micropowder intermediate is first held at 800℃ for 30 minutes in a vacuum environment, then a hydrogen-argon mixture with a volume ratio of 1:5 is introduced, the temperature is raised to 900℃, and held for 40 minutes. Finally, it is cooled to room temperature, and then the surface of the BR micropowder intermediate after gradient heating treatment is performed by argon plasma. After treatment with the first plasma at 180W for 10 minutes, SiN is deposited on the surface of the BR micropowder intermediate. x A transition layer was then formed, followed by treatment with a second plasma at 150 W for 15 min, and then applied to SiN. x A diamond film was deposited on the surface of the transition layer to obtain a 5 nm thick composite film; The first plasma consists of silane and nitrogen in a volume ratio of 1:3, and the second plasma consists of methane and hydrogen in a volume ratio of 2:1. S5. After vacuum annealing the BR micro powder intermediate with a composite film formed on its surface at 200°C for 1 hour, the BR micro powder product is obtained by air classification.

[0028] Example 3 This embodiment provides a process for preparing BR micropowder for the semiconductor industry, including the following steps: S1. Diamond monomers are crushed in a liquid nitrogen environment at -40℃ to obtain BR micro powder crude product. The BR micro powder crude product is coarsely classified to remove BR micro powder with a particle size greater than 20μm and a particle size less than 1μm, and then the primary BR micro powder is obtained. The crushing speed is 3500r / min and the ball-to-material ratio is 8:1. S2. The BR micro powder screened at the initial screening is prepared into a dispersion with a mass fraction of 10%. After the first classification by gravity sedimentation, the BR micro powder intermediate is obtained by gradient magnetic separation. S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 40°C for 30 minutes, and then washed with deionized water. The acidic mixture has a mass fraction of 5%, and the acidic mixture includes dilute nitric acid and hydrofluoric acid in a volume ratio of 4:1. S4. The cleaned BR micropowder intermediate is first held at 800℃ for 30 minutes in a vacuum environment, then a hydrogen-argon mixture with a volume ratio of 1:8 is introduced, the temperature is raised to 950℃, and held for 60 minutes. Finally, it is cooled to room temperature, and then the surface of the BR micropowder intermediate after gradient heating treatment is performed by argon plasma. After treatment with the first plasma at 220W for 15 minutes, SiN is deposited on the surface of the BR micropowder intermediate. x A transition layer was then formed, followed by treatment with a second plasma at 250 W for 25 min, and then applied to SiN. x A diamond film was deposited on the surface of the transition layer to obtain a composite film with a thickness of 10 nm; The first plasma consists of silane and nitrogen in a volume ratio of 1:5, and the second plasma consists of methane and hydrogen in a volume ratio of 3:1. S5. After vacuum annealing the BR micro powder intermediate with a composite film formed on its surface at 300°C for 1.5 hours, the BR micro powder product is obtained by air classification.

[0029] The following is a comparative analysis of Examples 1-3. The analysis results of Examples 1-3 are shown in Table 1: Table 1 Analysis results of Examples 1-3 As shown in Table 1, Example 3 has higher crushing strength, more thorough pickling, longer plasma treatment power and time, and higher annealing temperature. Therefore, the BR micro powder product obtained has the highest purity, the fewest metal impurities, the most uniform particle size distribution, and the smoothest surface. The process parameters of Example 2 are relatively mild, so the performance indicators are slightly lower than those of Examples 1 and 3. The process parameters of Example 1 are at an intermediate level, and the performance indicators are also between the two.

[0030] Comparative Example 1 The difference between this comparative example and Example 1 is that in step S1, the diamond monomer is crushed at room temperature to obtain BR micro powder crude product.

[0031] Comparative Example 2 The difference between this comparative example and Example 1 is that in step S3, the BR micro powder intermediate is acid-washed with 3% dilute nitric acid at 35°C for 25 minutes, and then washed with deionized water.

[0032] Comparative Example 3 The difference between this comparative example and Example 1 is that in step S4, only the surface of the BR micro powder intermediate after gradient heating treatment is performed by argon plasma, without depositing SiN. x Transition layer and diamond film.

[0033] The following is a comparative analysis of Example 1 and Comparative Examples 1-3. The analysis results of Example 1 and Comparative Examples 1-3 are shown in Table 2: Table 2. Analysis results of Example 1 and Comparative Examples 1-3 As can be seen from Example 1, Table 2 and Comparative Example 1, Comparative Example 1 suffered from severe micro-powder agglomeration and increased surface cracks due to the absence of liquid nitrogen for low-temperature crushing, resulting in increased particle size distribution deviation and increased impurity content. As can be seen from Example 1, Table 2 and Comparative Example 2, Comparative Example 2, due to the use of a single acid solution for pickling, is unable to remove sparingly soluble metal impurities, resulting in a significant decrease in purity and a substantial increase in the total amount of impurities. As can be seen from Example 1, Table 2 and Comparative Example 3, the surface roughness of Comparative Example 3 increased significantly due to the cancellation of composite film deposition, which could not meet the requirements of semiconductor manufacturing process for the surface smoothness of micro powder.

Claims

1. A process for preparing BR micropowder for the semiconductor industry, characterized in that, Includes the following steps: S1. Pre-treat diamond monomers to obtain primary BR micro powder; S2. The BR micro powder screened at the initial screening is prepared into a dispersion with a mass fraction of 5-10%. After the first classification by gravity sedimentation, the BR micro powder intermediate is obtained by gradient magnetic separation. S3. The BR micro powder intermediate is acid-washed in an acidic mixture at 25~40℃ for 20~30 min, and then washed with deionized water. S4. The cleaned BR micro powder intermediate is subjected to gradient heating in a vacuum environment, and then the surface of the BR micro powder intermediate after gradient heating is treated by argon plasma. Finally, a composite film is deposited on the surface of the BR micro powder intermediate. S5. After vacuum annealing the BR micro powder intermediate with a composite film formed on its surface at 200~300℃ for 1~1.5h, the BR micro powder product is obtained by air classification.

2. The preparation process of BR micro powder for the semiconductor industry according to claim 1, characterized in that, The specific method of S1 includes: Diamond monomers were crushed in a liquid nitrogen environment at -80~-40℃ to obtain crude BR powder. The crude BR powder was then coarsely classified to remove particles larger than 20μm and particles smaller than 1μm, resulting in primary BR powder.

3. The preparation process of BR micro powder for the semiconductor industry according to claim 2, characterized in that, The crushing speed is 2000~3500 r / min and the ball-to-material ratio is 5~8:

1.

4. The preparation process of BR micro powder for the semiconductor industry according to claim 1, characterized in that, The acidic mixture has a mass fraction of 2-5%, and includes dilute nitric acid and hydrofluoric acid in a volume ratio of 2-4:

1.

5. The preparation process of BR micro powder for the semiconductor industry according to claim 1, characterized in that, The gradient heating process specifically includes: First, hold the temperature in a vacuum environment at 800℃ for 30 minutes, then introduce a mixed gas with a volume ratio of 1:5~8, raise the temperature to 900~950℃, hold the temperature for 40~60 minutes, and finally cool to room temperature. The mixture includes hydrogen and argon.

6. The preparation process of BR micro powder for the semiconductor industry according to claim 1, characterized in that, Specific methods for depositing composite films on the surface of BR micron powder intermediates include: SiN was deposited on the surface of the BR micro powder intermediate after treatment with a first plasma at 180-220W for 10-15 minutes. x A transition layer is formed, followed by treatment with a second plasma at 150-250 W for 15-25 min, and then on SiN. x A diamond film is deposited on the surface of the transition layer to obtain a composite film.

7. The preparation process of BR micro powder for the semiconductor industry according to claim 6, characterized in that, The first plasma comprises silane and nitrogen in a volume ratio of 1:3 to 5, and the second plasma comprises methane and hydrogen in a volume ratio of 2 to 3:

1.

8. The preparation process of BR micro powder for the semiconductor industry according to claim 6, characterized in that, The thickness of the composite film is 5~10nm.

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