Method for rapidly removing large-particle powder in polishing solution

Abstract

The invention discloses a method for quickly removing large-particle powder in a polishing solution, which comprises the following steps of: preparing the polishing solution from polishing powder with a certain particle size span, and standing; in the standing time period of the polishing solution, taking out part of the suspension solution from the suspension layer of the polishing solution at certain time intervals, and diluting, so that the concentration of the taken-out suspension solution meets the test range of an absorbance detection instrument; and detecting the change relationship between the absorbance of the taken-out and diluted suspension solution and the selection time, selecting a proper time point according to the change relationship, carrying out vertical liquid separation on the polishing solution, retaining the upper-layer polishing solution, and removing the lower-layer polishing solution. Thus, large-particle powder in the polishing solution is removed by removing lower-layer separated liquid in the polishing solution, so that the particle size in the polishing solution is more concentrated, the stability of the polishing solution is improved, and the polishing effect is optimized. The method has the advantages of rapidness, scientificity, low cost and high efficiency.

Description

Technical Field

[0001] The invention relates to the technical field of chemical mechanical polishing, in particular to a method for rapidly removing large-particle powder in polishing liquid. Background Art

[0002] Chemical mechanical polishing (CMP) achieves material surface flatness by combining chemical and mechanical actions. As a key material for CMP, polishing fluid usually contains nano- and submicron-level abrasives and surfactant components. However, large-particle powders in the polishing fluid will scratch the material surface during the CMP process, reducing the quality of the polished surface and affecting the yield of the finished product. At the same time, their large size may also reduce polishing efficiency and increase energy consumption. The abrasive concentration and suspension in the polishing fluid directly affect the chemical reaction rate, and the presence of large-particle powders may interfere with these chemical reactions, thereby affecting the effect of the CMP process. The presence of large-particle powders may reduce the stability and uniformity of the polishing fluid, thereby affecting the polishing effect.

[0003] In order to reduce the harm of large-particle powder in the polishing liquid and its impact on the polishing quality, ball milling is usually used to prepare ultrafine powder materials. However, the current ball milling equipment is complex, and the ball milling method takes a long time to achieve effective grinding and dispersion, which may lead to reduced production efficiency. Especially when a large amount of large-particle powder needs to be removed, the ball milling process may be very time-consuming, which may lead to high energy consumption in the case of long-term operation. Although the ball milling method can significantly reduce the large-particle powder particles in the sample through long-term ball milling, long-term ball milling may also lead to over-grinding, causing the particles to disperse and introduce new impurities.

[0004] Therefore, there is an urgent need to establish a more scientific and efficient method for removing large-particle powder in the polishing liquid to solve the problem of low production efficiency and inability to guarantee product quality in the current ball milling method for preparing ultrafine powder materials. Summary of the invention

[0005] In order to solve the above technical problems, the embodiment of the present invention provides a method for quickly removing large particles of powder in the polishing liquid. The specific technical solution is as follows: In order to solve the above-mentioned technical problems, the present invention is achieved as follows: Provided is a method for rapidly removing large-particle powder in a polishing liquid, comprising the following steps: preparing a polishing liquid with polishing powder having a certain particle size span, and allowing the polishing liquid to stand; taking out a portion of a suspension solution from a suspension layer of the polishing liquid at certain intervals during the period of the polishing liquid standing, and diluting the suspension solution so that the concentration of the suspension solution taken out meets the test range of an absorbance detection instrument; detecting the relationship between the absorbance of the taken out and diluted suspension solution and the selected time, selecting a suitable time point according to the relationship, separating the polishing liquid into upper and lower layers, retaining the upper layer of the polishing liquid, and removing the lower layer of the polishing liquid.

[0006] In one of the embodiments, the mass concentration of the polishing powder in the configured polishing liquid is in the range of 5% to 30%.

[0007] In one embodiment, the mass concentration range of the polishing powder in the configured polishing liquid is preferably 10% to 20%.

[0008] In one embodiment, the polishing liquid has an obvious suspension layer within 0-1 hour of standing, and the suspension layer accounts for 90-100% of the total volume of the polishing liquid.

[0009] In one embodiment, the suspension layer preferably accounts for 98-100% of the total volume of the polishing liquid.

[0010] In one embodiment, the median particle size of the selected polishing powder is 0.1 to 9 microns.

[0011] In one embodiment, the median particle size of the selected polishing powder is preferably 0.6-5 microns.

[0012] In one embodiment, the taken out suspension solution is located in the middle of the suspension layer of the polishing liquid.

[0013] In one embodiment, the volume of the suspended solution removed is 1-5 ml.

[0014] In one embodiment, when detecting the relationship between the absorbance of the taken out and diluted suspension solution and the selection time, the selection time range is 0-3h, preferably 0-1h, and the absorbance of the selected corresponding suspension solution is tested at different time points within the selection time range to establish a curve of the relationship between the absorbance of the suspension layer and the selection time.

[0015] In the embodiment of the present invention, by establishing the change relationship between the absorbance of the suspension layer of the configured polishing liquid during the static process and the selected time, and selecting the appropriate time point according to the change relationship, the polishing liquid is separated into upper and lower liquids, the upper polishing liquid is retained, and the lower polishing liquid is removed. In this way, the removal of the lower liquid in the polishing liquid is achieved to remove the large particles of powder in the polishing liquid, so that the particle size in the polishing liquid is more concentrated, the stability of the polishing liquid is improved, and the polishing effect is optimized. The method of the present invention has the advantages of being fast, scientific, low-cost, and high-efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings: Figure 1 A flow chart of the steps of the method for rapidly removing large-particle powder from a polishing liquid according to the present invention; Figure 2 This is the particle size diagram of the polishing liquid with D50=1.262 microns of Example 1 of the present invention; Figure 3 The curve showing the relationship between the absorbance of the suspension layer and the selected time in Example 1 of the present invention; Figure 4 This is a particle size diagram of the upper polishing liquid after liquid separation for 1 hour in Example 1 of the present invention; Figure 5 This is a particle size diagram of the lower polishing liquid after liquid separation for 1 hour in Example 1 of the present invention; Figure 6 is a graph showing the relationship between particle size and time in Example 1 of the present invention; Figure 7 is a graph showing the relationship between absorbance and particle size (D50) of Example 1 of the present invention; Figure 8 This is the SEM of small particles (upper layer) after separation at 1 h in Example 1 of the present invention; Fig. 9 This is the SEM of large particles (lower layer) after separation for 1 h in Example 1 of the present invention; Fig.10 This is the polishing powder particle size diagram of D50=0.645 micron of Example 2 of the present invention; Fig.11 is a curve showing the relationship between absorbance and time of Example 2 of the present invention; Fig.12 This is the upper layer particle size diagram of Example 2 of the present invention after 15 minutes of liquid separation; Fig.13 This is the particle size diagram of the lower layer after 15 minutes of liquid separation in Example 2 of the present invention; Fig.14is a curve showing the relationship between absorbance and time of Example 3 of the present invention; Fig.15 The absorbance versus time curve of Example 4 of the present invention is Fig.16 This is a particle size diagram of the upper polishing liquid after liquid separation in 0.5h of the comparative example 1 of the present invention; Fig.17 This is a particle size diagram of the lower polishing liquid after liquid separation in 0.5h of Comparative Example 1 of the present invention; Fig.18 This is the particle size diagram of the upper polishing liquid after liquid separation for 1.5 hours in Comparative Example 2 of the present invention; Fig.19 This is the particle size diagram of the lower layer polishing liquid of Control Example 2 of the present invention after liquid separation for 1.5 hours. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] See also Figure 1 , which is a flow chart of the steps of the method for quickly removing large-particle powder in the polishing liquid of the present invention; as shown in the figure, the method for quickly removing large-particle powder in the polishing liquid of this embodiment includes the following steps S1 to S3. First, in step S1, the polishing liquid is configured: polishing powder with a certain particle size span is taken to configure the polishing liquid, and it is left to stand. The particle size span refers to the value of (D90-D10) / D50, where D90 is the maximum particle size of the polishing powder, D10 is the minimum particle size of the polishing powder, and D50 is the median particle size of the polishing powder, and the larger the value of the particle size span, the more obvious the removal effect of the method on large particles. The median particle size D50 of the selected polishing powder is 0.1~9 microns, preferably 0.6~5 microns. The mass concentration range of the polishing powder in the configured polishing liquid is 5%~30%, preferably 10%~20%.

[0019] Next, in S2, the measuring liquid is taken from the polishing liquid at different time periods: during the period of the polishing liquid being at rest, part of the suspended solution is taken out from the suspension layer of the polishing liquid at intervals, and diluted so that the concentration of the taken out suspended solution meets the test range of the absorbance detection instrument. In this embodiment, the polishing liquid has an obvious suspended layer within 0-1 hour of standing, and the suspension layer accounts for 90-100% of the total volume of the polishing liquid, preferably 98-100%. The taken out suspended solution is located in the middle of the suspension layer of the polishing liquid, and the volume of the taken out suspended solution is 1-5 ml.

[0020] Finally, the suspension is layered in S3: the relationship between the absorbance of the taken out and diluted suspension solution and the selected time is detected, and the appropriate time point is selected according to the change relationship, the polishing liquid is separated into upper and lower liquids, the upper polishing liquid is retained, and the lower polishing liquid is removed, and the removal of large particles of powder in the polishing liquid is achieved by removing the lower liquid in the polishing liquid. The range of the selected time is 0-3h, preferably 0-1h. The absorbance of the selected corresponding suspension solution is tested at different time points within the selected time range, and a curve of the change relationship between the absorbance of the suspension layer and the selected time is established. According to the change relationship curve, a suitable time point is selected to separate the polishing liquid into upper and lower liquids, and the suitable time point here refers to the time point at which the absorbance of the suspension layer changes significantly with time. In this way, the removal of large particles of powder in the polishing liquid is achieved by removing the lower liquid in the polishing liquid.

[0021] The method for quickly removing large-particle powder in the polishing liquid of this embodiment establishes a curve relationship between the absorbance of the suspension layer of the configured polishing liquid during the static process and the selected time, and selects a suitable time point according to the curve relationship to separate the polishing liquid into upper and lower layers, retain the upper polishing liquid, and remove the lower polishing liquid. In this way, the large-particle powder in the polishing liquid is removed by removing the lower layer of the polishing liquid, so that the particle size in the polishing liquid is more concentrated, the stability of the polishing liquid is improved, and the polishing effect is optimized. The method of this embodiment has the advantages of being fast, scientific, low-cost, and high-efficiency.

[0022] The beneficial effects of the method for rapidly removing large-particle powder in polishing liquid of the present invention will be described below with specific examples.

[0023] Example 1 1. Select polishing powder with a certain particle size span R0 and a median particle size D50 of 1.262 microns, and prepare it into a polishing liquid with a mass percentage of 20%, wherein D10 is 0.637 microns, the median particle size D50 is 1.262 microns, and D90 is 5.195 microns. The value of R0=(D90-D10) / D50 is 3.61, indicating that there is a certain proportion of large-particle powder in the polishing liquid. The particle size analysis is as follows: Figure 2 shown.

[0024] 2. Within 0-1h after the polishing liquid is prepared, there is an obvious suspension layer, and the suspension layer accounts for more than 98% of the total volume. After the polishing liquid is prepared, 2ml of liquid is selected from the middle of the suspension layer every half an hour, and 28ml of water is added to dilute it and its absorbance is tested by UV-visible spectrophotometer. The relationship curve between the absorbance of the suspension layer and the selection time is as follows: Figure 3 shown.

[0025] 3. According to Figure 2 It can be seen that with the change of selected time, the absorbance of the suspension layer changes significantly before 1 hour, so 1 hour is selected as the appropriate time point for liquid separation. After liquid separation, the particle size distribution of the upper liquid and the lower liquid is tested respectively. The results are as follows Figure 4 and Figure 5 , at this time, the span R1 of the upper polishing liquid is 1.12, and the span R2 of the lower polishing liquid is 3.40, R1<R2<R0. It can be seen that after the separation of the polishing liquid, the particle size span of the upper and lower liquids is reduced, and the particle size distribution is more concentrated; the lower polishing liquid is put into the oven for drying, and after drying, the lower layer is about 27.3% of the total weight. The particle size span and mass distribution of the polishing liquid after the upper and lower separation above show that the method of the present invention can effectively remove large particles in the polishing liquid, reduce the particle size span R, and the yield of the upper polishing liquid is greater than 70%.

[0026] Furthermore, the liquid particle sizes selected at different time points were analyzed, and the results are as follows: Figure 6 The relationship between D50 and absorbance is shown in Figure 7 .according to Figure 6 and Figure 7 It can be concluded that the change trend of absorbance and particle size is consistent. Therefore, the particle size can be determined based on absorbance, and the liquid can be drained when the absorbance change rate decreases to remove large particles. Therefore, it is more scientific and effective to remove large particles within 1 hour.

[0027] At the same time, the upper and lower layers of polishing liquid after the above separation are subjected to scanning electron microscopy, such as Figure 8 and Fig. 9 As shown, small particles are evenly distributed, while large particles are more dispersed, which further illustrates that large particles are removed more completely.

[0028] Example 2 1. Select polishing powder with a certain particle size span and a median particle size D50 of 0.645 microns. The particle size analysis is shown in Fig.10 , it was prepared into a polishing liquid with a mass percentage of 5%, D10 was 0.209 microns, the median particle size D50 was 0.645 microns, D90 was 1.887 microns, and the R value was 2.60, indicating that there was a certain proportion of large-particle powder in the polishing liquid.

[0029] 2. Within 0-1h after the polishing liquid is prepared, there is an obvious suspension layer, and the suspension layer accounts for more than 98% of the total volume. After the polishing liquid is prepared, select 2ml of liquid from the middle of the suspension layer every half an hour, add 28ml of water to dilute it, and test its absorbance by UV-visible spectrophotometer, and draw a curve of the relationship between the absorbance of the suspension layer and the selection time, such as Fig.11 shown.

[0030] 3. According to Fig.11 It can be seen that the most suitable time point for liquid separation is 15 minutes. After liquid separation, the particle size distribution of the upper liquid and the lower liquid is tested respectively, as shown in Figure 2. Fig.12 and Fig.13 The particle size spans of the upper and lower layers are 1.34 and 1.96 respectively. Compared with the initial particle size span, the particle size span after separation is reduced. The particle size span of the polishing liquid after separation is reduced and the particle size distribution is more concentrated. Large particles account for 25% of the total weight, and large particles are effectively removed.

[0031] Example 3 1. Select polishing powder with a certain particle size span and a median particle size D50 of 0.645 microns. The particle size analysis is shown in Fig.13 , it was prepared into a polishing liquid with a mass percentage of 30%, D10 was 0.209 microns, the median particle size D50 was 0.645 microns, D90 was 1.887 microns, and the R value was 2.60, indicating that there was a certain proportion of large-particle powder in the polishing liquid.

[0032] 2. Within 0-1h after the polishing liquid is prepared, there is an obvious suspension layer, and the suspension layer accounts for more than 98% of the total volume. After the polishing liquid is prepared, select 2ml of liquid from the middle of the suspension layer every half an hour, add 28ml of water to dilute it, and test its absorbance by UV-visible spectrophotometer, and draw a curve of the relationship between the absorbance of the suspension layer and the selection time, such as Fig.14 shown.

[0033] 3. According to Fig.14 It can be seen that the most suitable time point for liquid separation is 15 minutes. After liquid separation, the particle size distribution of the upper and lower layers is analyzed respectively to find out the span of the upper and lower layers. Compared with the initial span, the span after liquid separation is reduced. The particle size distribution of the polishing liquid after liquid separation is more concentrated, and large particles are effectively removed.

[0034] Example 4 1. Select polishing powder with a certain particle size span and a median particle size D50 of 9.289 microns, and prepare it into a polishing liquid with a mass percentage of 20%. The D90 is 23.12 microns and the R value is 2.08, indicating that there is a certain proportion of large-particle powder in the polishing liquid.

[0035] 2. Within 0~1h after the polishing liquid is prepared, there is an obvious suspension layer, and the suspension layer accounts for more than 98% of the total volume. After the polishing liquid is prepared, select 2ml of liquid from the middle of the suspension layer every half an hour, add 28ml of water to dilute it, and test its absorbance by UV-visible spectrophotometer, and draw a curve of the relationship between the absorbance of the suspension layer and the selection time, such as Fig.15 .

[0036] 3. According to Fig.15 It can be seen that the most suitable time point for liquid separation is 15 minutes. After liquid separation, the particle size distribution of the lower liquid and the upper liquid are tested respectively, and the span of the upper and lower layers is calculated. Compared with the initial span, the span after liquid separation is reduced. The particle size distribution of the polishing liquid after liquid separation is more concentrated, and large particles are effectively removed.

[0037] Comparative Example 1 The difference between this control example 1 and the above-mentioned embodiment 1 is that the liquid separation time in this control example 1 is modified to 0.5h, and other conditions are consistent with those in embodiment 1. Therefore, the steps of this control example 1 please refer to those shown in the above-mentioned embodiment 1, and will not be repeated here.

[0038] After the polishing liquid was allowed to stand for 0.5 h, the particle size distribution of the upper and lower liquids was tested. The results are as follows: Fig.16 and Fig.17 As shown, at this time, the span R3 of the upper polishing liquid is 1.92, the span R4 of the lower polishing liquid is 3.03, R1<R3<R4<R2<R0. It can be seen that after liquid separation at 0.5h, the particle size span of the polishing liquid after separation is reduced and the particle size distribution becomes concentrated. However, compared with the liquid separation at 1h, the large particle removal effect is obviously worse. The particle size diagram can also confirm that the large particle removal effect is not good, which indirectly illustrates the scientific nature of liquid separation at 1h.

[0039] Comparative Example 2 The difference between this control example 1 and the above-mentioned embodiment 1 is that the liquid separation time in this control example 1 is modified to 1.5h, and the other conditions are consistent with those in embodiment 1. Therefore, the steps of this control example 1 please refer to those shown in the above-mentioned embodiment 1, and will not be repeated here.

[0040] After the polishing liquid was allowed to stand for 1.5 hours, the particle size distribution of the upper and lower liquids was tested. The results are as follows: Fig.18 and Fig.19As shown, at this time, the span R5 of the upper polishing liquid is 0.6, and the span R6 of the lower polishing liquid is 3.67, R5<R1<R3<R4<R2<R0<R6. It can be seen that after liquid separation at 1.5h, the particle size span of the polishing liquid after separation is reduced and the particle size distribution is more concentrated; the upper span R5 is less than the upper span R1 at 1h, and the lower span R6 is greater than the lower span R2 at 1h, which means that at this time the upper particles are very concentrated, the lower particles are more, the large particles are removed well, but the small particles are also removed, and the corresponding yield is low. The lower layer is about 39.7% of the total weight, and a certain amount of small-particle polishing liquid is lost accordingly, which indirectly shows that the liquid separation at 1h is fast, effective and scientific.

[0041] In summary, the present invention provides a method for quickly removing large-particle powder in a polishing liquid, by establishing a relationship between the absorbance of a suspension layer of a configured polishing liquid during a static state and the selected time, and selecting a suitable time point according to the relationship, the polishing liquid is separated into upper and lower layers, the upper layer of the polishing liquid is retained, and the lower layer of the polishing liquid is removed, so that the large-particle powder in the polishing liquid is removed by removing the lower layer of the liquid in the polishing liquid, so that the particle size in the polishing liquid is more concentrated, the stability of the polishing liquid is improved, and the polishing effect is optimized. The method of the present invention has the advantages of being fast, scientific, low-cost, and high-efficiency.

[0042] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0043] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation modes, which are merely illustrative rather than restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are within the protection of the present invention.

Claims

1. A method for quickly removing large particles of powder in a polishing liquid, characterized in that: The following steps are involved: Take polishing powder with a certain particle size span to prepare polishing liquid and let it stand; During the period of time when the polishing liquid is at rest, a portion of the suspension solution is taken out from the suspension layer of the polishing liquid at regular intervals, and the suspension solution is diluted so that the concentration of the taken out suspension solution meets the test range of the absorbance detection instrument; The relationship between the absorbance of the taken out and diluted suspension solution and the selected time is detected, and a suitable time point is selected according to the relationship, the polishing liquid is separated into upper and lower layers, the upper polishing liquid is retained, and the lower polishing liquid is removed.

2. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: The mass concentration range of the polishing powder in the configured polishing liquid is 5% to 30%.

3. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1 or 2, characterized in that: The mass concentration range of the polishing powder in the configured polishing liquid is preferably 10% to 20%.

4. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: The polishing liquid has an obvious suspension layer within 0-1 hour of standing, and the suspension layer accounts for 90-100% of the total volume of the polishing liquid.

5. The method for rapidly removing large-particle powder in a polishing liquid according to claim 4, characterized in that: The suspension layer preferably accounts for 98-100% of the total volume of the polishing liquid.

6. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: The median particle size of the selected polishing powder is 0.1 to 9 microns.

7. The method for rapidly removing large-particle powder in a polishing liquid according to claim 6, characterized in that: The median particle size of the selected polishing powder is preferably 0.6 to 5 microns.

8. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: The taken-out suspension solution is located in the middle of the suspension layer of the polishing liquid.

9. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: The volume of the suspended solution taken out is 1-5 ml.

10. The method for rapidly removing large-particle powder in a polishing liquid according to claim 1, characterized in that: When detecting the relationship between the absorbance of the suspended solution after being taken out and diluted and the selection time, the selection time range is 0-3h, preferably 0-1h, and the absorbance of the selected corresponding suspension solution is tested at different time points within the selection time range to establish a curve of the relationship between the absorbance of the suspension layer and the selection time.

Images