Silicon oxide nano-particles with controllable morphology and application of silicon oxide nano-particles

Abstract

The invention belongs to the technical field of silicon oxide nano-particle preparation, and particularly relates to a shape-controllable silicon oxide nano-particle and application thereof, the silicon oxide nano-particle is prepared from a silicon source, a buffer agent, ethanol and deionized water; the weight ratio of the silicon source to the buffer agent to the ethanol to the deionized water is (90-110): (12-15): (150-180): (515-550). The silicon oxide nanoparticles prepared by the method can be applied to a rough polishing stage and a fine polishing stage in chemical mechanical polishing of semiconductors, and the requirements of the high-end application field are met by controlling the morphology.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterial preparation, and particularly relates to a silica nanoparticle with controllable morphology and its application. Background Art

[0002] As a key nanomaterial, silica nanoparticles play a crucial role in the field of semiconductor chemical mechanical polishing (CMP). CMP is one of the core processes in semiconductor chip manufacturing. Its principle is to achieve planarization of the wafer surface through the synergistic effect of chemical etching and mechanical grinding to meet the stringent requirements for the flatness between different material layers in chip manufacturing. In this process, silica nanoparticles, as the key abrasive component of the polishing liquid, directly affect the polishing effect and the manufacturing quality of the chips.

[0003] With the continuous development of semiconductor technology towards higher integration and smaller process dimensions, the chip manufacturing process poses unprecedented challenges to the precision, efficiency, and surface quality of the CMP process. For silica nanoparticles, their application in the CMP field faces many problems. In terms of purity, even trace amounts of metal impurities in silica nanoparticles, such as metal ions like sodium, potassium, and iron, may diffuse into the silicon wafer or electronic devices during the CMP process, causing serious problems such as short circuits, resulting in a decline in chip performance or even scrapping. Therefore, the demand for ultra-high purity silica nanoparticles is becoming increasingly urgent.

[0004] In terms of the morphology of silica nanoparticles, different CMP stages have different requirements for the particle size and shape of silica nanoparticles. In the rough polishing stage, in order to achieve a higher removal rate, larger particle size abrasives are required; while in the fine polishing stage, more attention is paid to surface flatness, and smaller particle size abrasives are preferred. At the same time, non-spherical silica nanoparticles, such as peanut-shaped and irregular-shaped ones, have received extensive attention because they can increase the contact area between abrasive particles and the wafer, improve friction, and thus enhance the polishing rate. However, existing technologies face many difficulties in preparing silica nanoparticles with specific morphology and particle size distribution. Traditional preparation methods, such as ion exchange method, hydrolysis of elemental silicon method, and sol-gel method, etc., are difficult to precisely control the morphology and particle size of silica nanoparticles.

[0005] Currently, CN102390838A discloses a method for preparing non-spherical silica nanoparticles, but it requires the preparation of seeds and the synthesis process flow is relatively complex. CN111498856B discloses a two-phase preparation method for high-purity silica nanoparticles, but its morphology control agent is expensive and the control of the two-phase process is complex. Existing preparation methods of silica nanoparticles have many deficiencies in controlling the morphology of silica nanoparticles and cannot meet the requirements of high-end application fields.

[0006] In summary, developing a preparation method of silicon oxide nanoparticles that can effectively solve the above problems is of great practical significance for promoting the progress of semiconductor CMP technology and meeting the growing chip manufacturing demands. Summary of the Invention

[0007] The object of the present invention is to provide silicon oxide nanoparticles with controllable morphology to solve the problem that the morphology of silicon oxide nanoparticles is difficult to control in the prior art. The silicon oxide nanoparticles provided by the present invention have characteristics such as high compactness, controllable morphology, and stable performance, and have high industrial practical value.

[0008] The specific technical solutions are as follows:

[0009] A kind of silicon oxide nanoparticles with controllable morphology, the nanoparticles are prepared from a silicon source, a buffer, ethanol and deionized water; the weight ratio of the silicon source to the buffer, alcohol organic solvent and deionized water is (90-110):(12-15):(150-180):(515-550).

[0010] Further, the buffer includes any one or a combination of two of organic amines and amino acids; the organic amines include any one or several of ethylenediamine, butanediamine, dipropanolamine, and ammonia water; the amino acids include any one of arginine and lysine.

[0011] Further, the silicon source includes any one of tetraethoxysilane and tetramethoxysilane.

[0012] Further, the alcohol organic solvent includes any one of ethanol and methanol.

[0013] Further, the metal impurity content of the silicon oxide nanoparticles is less than 1 ppm, the DLS average particle size is 10-100 nm, and the particle association degree is 1-3.

[0014] Further, the morphology of the silicon oxide nanoparticles is spherical or peanut-shaped.

[0015] The present invention also provides an application of the silicon oxide nanoparticles with controllable morphology in semiconductor preparation.

[0016] Further, the application includes the rough polishing stage and the fine polishing stage in semiconductor chemical mechanical polishing.

[0017] Advantageous Effects:

[0018] 1. In the actual work and research, the inventors of the present invention found that the morphology of silica nanoparticles is mainly related to the hydrolysis rate of the silicon source and the adsorptive additives in the reaction solution. Therefore, in the present invention, by controlling the proportions of deionized water, ethanol, and tetraethoxysilane in the hydrolysis solution, the hydrolysis rate of the silicon source can be effectively controlled. And in the reaction process of the present invention, by adding long-chain organic amines and amino acids, the organic amines and amino acids can be adsorbed on the surface of the silicon source during the reaction process, thereby controlling the polymerization process of the silicon source. Through the above two steps, the growth process of silica nanoparticles can be controlled, thus realizing the control of the morphology.

[0019] 2. In the present invention, an organic amine and amino acid system is used in the reaction, making the overall reaction system have a certain buffering effect, and there is no need to use other alkaline substances to adjust the pH during the reaction process, simplifying the experimental steps. At the same time, compared with the preparation and concentration by heating and evaporation in the preparation of other silica nanoparticles, the present invention realizes solvent replacement and filtration concentration through the ultrafiltration method, reducing energy consumption. Brief Description of the Drawings

[0020] Figure 1 It is the TEM image of the silica nanoparticles in Example 1 of the present invention;

[0021] Figure 2 It is the TEM image of the silica nanoparticles in Example 2 of the present invention;

[0022] Figure 3 It is the TEM image of the silica nanoparticles in Example 4 of the present invention. Detailed Embodiments

[0023] The technical solutions of the present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0024] Example 1

[0025] This example provides a method for preparing silica nanoparticles with controllable morphology, including the following steps:

[0026] (1) Prepare an alkaline solution: Select an alkaline organic substance with buffering ability, dissolve it in deionized water, and prepare an alkaline solution with a pH value between 8 and 10.5;

[0027] Specifically, select butanediamine as the buffering reagent, weigh 12 g of butanediamine, add it to 488 g of deionized water, stir evenly to obtain an alkaline solution, and the pH of the alkaline solution is 10.

[0028] (2) Prepare a hydrolysis solution: Mix deionized water, ethanol, and tetraethoxysilane in proportion, and stir evenly to prepare a hydrolysis solution;

[0029] Specifically, 60 g of deionized water, 150 g of ethanol, and 90 g of tetraethoxysilane were stirred and mixed at 500 rpm for 1 h at 10°C to obtain a hydrolysis solution after uniform mixing.

[0030] (3) Preparation of silica nanoparticle solution: The hydrolysis solution prepared in step (2) was added to the alkali solution prepared in step (1) in batches at intervals. After the addition was completed, continuous stirring reaction was carried out to obtain a silica nanoparticle solution;

[0031] Specifically, the hydrolysis solution was added to the above alkali solution in 5 batches, with an interval of 20 min between each addition. After the addition was completed, the reaction was continued for 2 h. During the addition and reaction, the temperature was controlled at 30°C, the stirring speed was 500 rpm, and the pH of the reaction solution was 10. After the reaction was completed, a silica nanoparticle solution was obtained.

[0032] (4) Filtration and concentration: The silica nanoparticle solution in step (3) was first filtered through a large-pore ultrafiltration membrane and then through a small-pore ultrafiltration membrane. During this process, ultrapure water was added for solvent replacement and concentration, and finally, silica nanoparticles with controllable morphology were obtained.

[0033] Specifically, ultrafiltration treatment was carried out on the silica nanoparticle solution. First, an ultrafiltration membrane with a pore size of 0.5 μm was selected to filter out large particle impurities; then, the ultrafiltration membrane was replaced with a 0.02-μm one, and ultrapure water was added multiple times for solvent replacement while concentrating until the solid content of the silica nanoparticle solution reached 30 wt%, obtaining silica nanoparticles. The prepared silica nanoparticles are basically as shown in the appendix Figure 1 shown.

[0034] Example 2

[0035] This example provides a method for preparing silica nanoparticles with controllable morphology, including the following steps:

[0036] (1) Preparation of alkali solution: Select an alkaline organic substance with buffering ability and dissolve it in deionized water to prepare an alkali solution with a pH value between 8 and 10.5;

[0037] Specifically, select butanediamine and dipropanolamine as buffering reagents, weigh 5 g of butanediamine and 10 g of dipropanolamine, add them to 485 g of deionized water, and stir evenly to obtain an alkali solution with a pH of 9.5.

[0038] (2) Preparation of hydrolysis solution: Mix deionized water, ethanol, and tetraethoxysilane in proportion and stir evenly to prepare a hydrolysis solution;

[0039] Specifically, 30 g of deionized water, 180 g of ethanol, and 90 g of tetraethoxysilane were stirred and mixed at 500 rpm for 1 h at 15°C to obtain a hydrolysis solution after uniform mixing.

[0040] (3) Preparation of silica nanoparticle solution: The hydrolyzate prepared in step (2) is added to the alkali solution prepared in step (1) at intervals in portions. After the addition is completed, continuous stirring reaction is carried out to obtain the silica nanoparticle solution;

[0041] Specifically, the hydrolyzate is added to the above alkali solution in 4 portions, with an interval of 20 min between each addition. After the addition is completed, the reaction continues for 2 h. During the addition and reaction process, the temperature is controlled at 30 °C, the stirring speed is 500 rpm, and the pH of the reaction solution is 9.5. After the reaction is completed, the silica nanoparticle solution is obtained.

[0042] (4) Filtration and concentration: The silica nanoparticle solution in step (3) is first filtered through a large-pore ultrafiltration membrane and then through a small-pore ultrafiltration membrane. During this period, ultrapure water is added for solvent replacement and concentration, and finally silica nanoparticles with controllable morphology are obtained.

[0043] Specifically, ultrafiltration treatment is carried out on the silica nanoparticle solution. First, an ultrafiltration membrane with a pore size of 0.5 μm is selected to filter out large particle impurities; then, the ultrafiltration membrane is replaced with a 0.02-μm one, and ultrapure water is added multiple times for solvent replacement while concentration is carried out until the solid content of the silica nanoparticle solution reaches 30 wt%, and silica nanoparticles are obtained. The prepared silica nanoparticles are basically as shown in the appendix Figure 2 shown.

[0044] Example 3

[0045] This example provides a method for preparing silica nanoparticles with controllable morphology, including the following steps:

[0046] (1) Preparation of alkali solution: Select an alkaline organic substance with buffering capacity, dissolve it in deionized water, and prepare an alkali solution with a pH value between 8 and 10.5;

[0047] Specifically, lysine and butanediamine are selected as buffering reagents. 8 g of lysine and 6 g of butanediamine are weighed and added to 486 g of deionized water. After stirring evenly, the alkali solution is obtained, and the pH of the alkali solution is 9.8.

[0048] (2) Preparation of hydrolyzate: Mix deionized water, ethanol and tetraethoxysilane in proportion and stir evenly to prepare the hydrolyzate;

[0049] Specifically, 50 g of deionized water, 150 g of ethanol and 100 g of tetraethoxysilane are stirred and mixed at 15 °C and 500 rpm for 1 h. After mixing evenly, the hydrolyzate is obtained.

[0050] (3) Preparation of silicon oxide nanoparticle solution: The hydrolysis solution prepared in step (2) is added to the alkali solution prepared in step (1) at intervals in portions. After the addition is completed, continuous stirring reaction is carried out to obtain the silicon oxide nanoparticle solution;

[0051] Specifically, the hydrolysis solution is added to the above alkali solution in 4 portions, with an interval of 30 min between each addition. After the addition is completed, the reaction continues for 2 h. During the addition and reaction, the temperature is controlled at 30 °C, the stirring speed is 500 rpm, and the pH of the reaction solution is 9.8. After the reaction is completed, the silicon oxide nanoparticle solution is obtained.

[0052] (4) Filtration and concentration: The silicon oxide nanoparticle solution in step (3) is first filtered through a large-pore ultrafiltration membrane, and then filtered through a small-pore ultrafiltration membrane. During this process, ultrapure water is added for solvent replacement and concentration, and finally silicon oxide nanoparticles with controllable morphology are obtained.

[0053] Specifically, ultrafiltration treatment is carried out on the silicon oxide nanoparticle solution. First, an ultrafiltration membrane with a pore size of 0.5 μm is selected to filter out large particle impurities; then, an ultrafiltration membrane with a pore size of 0.02 μm is replaced, and ultrapure water is added multiple times for solvent replacement while concentrating until the solid content of the silicon oxide nanoparticle solution reaches 30 wt%, and silicon oxide nanoparticles are obtained.

[0054] Example 4

[0055] This example provides a method for preparing silicon oxide nanoparticles with controllable morphology, including the following steps:

[0056] (1) Preparation of alkali solution: Select an alkaline organic substance with buffering capacity, dissolve it in deionized water, and prepare an alkali solution with a pH value between 8 and 10.5;

[0057] Specifically, lysine is selected as the buffering reagent, 15 g of lysine is weighed, added to 485 g of deionized water, and after stirring evenly, the alkali solution with a pH of 9.3 is obtained.

[0058] (2) Preparation of hydrolysis solution: Mix deionized water, ethanol, and tetraethoxysilane in proportion and stir evenly to prepare the hydrolysis solution;

[0059] Specifically, 30 g of deionized water, 160 g of ethanol, and 110 g of tetraethoxysilane are stirred and mixed at 500 rpm at 20 °C for 1 h, and after mixing evenly, the hydrolysis solution is obtained.

[0060] (3) Preparation of silicon oxide nanoparticle solution: The hydrolysis solution prepared in step (2) is added to the alkali solution prepared in step (1) at intervals in portions. After the addition is completed, continuous stirring reaction is carried out to obtain the silicon oxide nanoparticle solution;

[0061] Specifically, the hydrolysis solution was added to the above-mentioned alkali solution in 5 portions at intervals of 30 min each. After the addition was completed, the reaction continued for 2 h. During the addition and reaction, the temperature was controlled at 25 °C, the stirring speed was 500 rpm, and the pH of the reaction solution was 9.3. After the reaction was completed, a silica nanoparticle solution was obtained.

[0062] (4) Filtration and concentration: The silica nanoparticle solution in step (3) was first filtered through a large-pore ultrafiltration membrane and then through a small-pore ultrafiltration membrane. During this process, ultrapure water was added for solvent replacement and concentration, and finally, silica nanoparticles with controllable morphology were obtained.

[0063] Specifically, the silica nanoparticle solution was subjected to ultrafiltration treatment. First, an ultrafiltration membrane with a pore size of 0.5 μm was selected to filter out large particle impurities; then, the ultrafiltration membrane was replaced with one having a pore size of 0.02 μm, and ultrapure water was added multiple times for solvent replacement and concentration simultaneously until the solid content of the silica nanoparticle solution reached 30 wt%, obtaining silica nanoparticles. The prepared silica nanoparticles are basically as shown in the appendix Figure 3 shown.

[0064] Example 5

[0065] The difference between this example and Example 4 is that arginine was used instead of lysine as the buffer reagent, and the addition amount was the same. The pH during the reaction process of the alkali solution and the hydrolysis solution was 10.3, and the other steps and parameters were the same.

[0066] Comparative Example 1

[0067] The difference between this comparative example and Example 1 is that more butanediamine was added during the preparation of the alkali solution, specifically 30 g of butanediamine and 480 g of deionized water. The other steps were the same, and the pH during the reaction process of the alkali solution and the hydrolysis solution was 11.5. The other steps and parameters were the same as those in Example 1.

[0068] Comparative Example 2

[0069] The difference between this comparative example and Example 2 is that the proportion of deionized water increased during the preparation of the hydrolysis solution. Specifically, it was 100 g of deionized water, 110 g of ethanol, and 90 g of tetraethoxysilane. The pH during the reaction process of the alkali solution and the hydrolysis solution was 9.4, and the other preparation steps and parameters were the same as those in Example 2.

[0070] Comparative Example 3

[0071] The difference between this comparative example and Example 3 is that in the step of reacting to form the silica nanoparticle solution, the reaction temperature of the hydrolysis solution and the alkali solution was controlled at 40 °C, and the reaction time was 1 h. The pH during the reaction process of the alkali solution and the hydrolysis solution was 9.7. The other steps and parameters were the same as those in Example 3.

[0072] Comparative Example 4

[0073] This comparative example provides a method for preparing silica nanoparticles with controllable morphology, comprising the following steps:

[0074] (1) Prepare an alkaline solution: Select an alkaline organic compound with buffering capacity, dissolve it in deionized water, and prepare an alkaline solution with a pH value between 8 and 10.5;

[0075] Specifically, select ethylenediamine and ammonia water as buffering reagents, weigh 5 g of ethylenediamine and 10 g of ammonia water, add them to 485 g of deionized water, and stir evenly to obtain an alkaline solution with a pH of 9.3.

[0076] (2) Prepare a hydrolysis solution: Mix deionized water, ethanol, and tetraethoxysilane in proportion and stir evenly to prepare a hydrolysis solution;

[0077] Specifically, mix 150 g of deionized water, 100 g of ethanol, and 50 g of tetraethoxysilane at 30 °C with stirring at 500 rpm for 1 h, and stir evenly to obtain a hydrolysis solution.

[0078] (3) Prepare a silica nanoparticle solution: Add the hydrolysis solution directly to the above alkaline solution at one time, and react for 3 h after the addition is completed. During the addition and reaction, control the temperature at 30 °C, the stirring speed at 500 rpm, and the pH of the reaction solution at 11. After the reaction is completed, a silica nanoparticle solution is obtained.

[0079] (4) Filter and concentrate: First filter the silica nanoparticle solution in step (3) through a large-pore ultrafiltration membrane, and then filter it through a small-pore ultrafiltration membrane. During this process, add ultrapure water for solvent replacement and concentration, and finally obtain silica nanoparticles with controllable morphology.

[0080] Specifically, perform ultrafiltration treatment on the silica nanoparticle solution. First, select an ultrafiltration membrane with a pore size of 0.5 μm to filter and remove large particle impurities; then replace it with a 0.02-μm ultrafiltration membrane, add ultrapure water multiple times for solvent replacement, and at the same time perform concentration until the solid content of the silica nanoparticle solution reaches 30 wt%, to obtain silica nanoparticles.

[0081] Detect the morphology of the silica nanoparticles prepared in the above examples and comparative examples. The detection results are shown in Table 1 and the attached drawings below. The detection method for the primary particle size is: Obtain the specific surface area S by the BET specific surface area test method BET , and then calculate it by the formula d = 2727 / S BE . The secondary particle size is measured by a Malvern particle size analyzer Zetasizer Lab. The degree of association is the ratio of the secondary particle size to the primary particle size. The gold impurity concentration is measured by an Agilent ICP-MS7700S.

[0082] Statistical Table of Test Results of Silicon Oxide Nanoparticle Parameters in Examples and Comparative Examples

[0083]

[0084] By adjusting different components of raw materials and process of the production process, the present invention obtains silicon oxide nanoparticles with different particle sizes and different degrees of association. By comparing Examples 1, 2, 3, 4, 5 with Comparative Example 4, it can be seen that the organic amines and amino acids used in the present invention can effectively control the morphology of silicon oxide nanoparticles and obtain different degrees of association. Long-chain organic amines or amino acids can be adsorbed on the surface of silicon oxide nanoparticles to adjust the charge state on the particle surface, thereby affecting their polymerization growth.

[0085] By comparing Example 1 with Comparative Example 1, it can be seen that the increase in organic amines promotes the nucleation process, thereby reducing the particle size and degree of association of silicon oxide nanoparticles. The size of the degree of association is related to the morphology and size of the particles. The larger the degree of association, the more deviated its shape is from a sphere. Different degrees of association reflect the differences in actual morphology. The prepared nano-silicon oxides of the present invention have a wide range of degrees of association, and actually can prepare nano-silicon oxides with multiple sizes and morphologies to meet the different requirements for the particle size and shape of silicon oxide nanoparticles in different CMP stages.

[0086] By comparing Example 2 with Comparative Example 2, it can be seen that the increase in the proportion of deionized water will cause more hydrolysis of the silicon source, thereby reducing the degree of association of silicon oxide nanoparticles.

[0087] By comparing Example 3 with Comparative Example 3, it can be seen that increasing the temperature can increase the polycondensation rate of silicon oxide nanoparticles, complete the growth of silicon oxide nanoparticles in a shorter time, and the degree of association is also higher.

[0088] And in the silicon oxide nanoparticle solution prepared by the method of the present application, the gold impurity content can be less than 1 ppm. Compared with the gold impurity content in the silica sol prepared by the ion exchange method, which is in the dozens or hundreds of ppm, and even some metal contents exceed 10,000 ppm, the prepared silicon oxide nanoparticles of the present invention have higher purity and can meet higher-end requirements.

[0089] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-limiting. In addition, it should be understood that although this specification is described according to the embodiments, it does not only include one technical solution. The narrative way of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A silica nanoparticle with controllable morphology, characterized in that, The nanoparticles are prepared from a silicon source, a buffer, ethanol and deionized water; the weight ratio of the silicon source to the buffer, the alcohol organic solvent and deionized water is (90-110):(12-15):(150-180):(515-550).

2. The silica nanoparticles with controllable morphology according to claim 1, wherein The buffer includes any one or a combination of two of organic amines and amino acids; the organic amines include any one or several of ethylenediamine, butanediamine, dipropanolamine, and ammonia water; the amino acids include any one of arginine and lysine.

3. The method for preparing the silica nanoparticles with controllable morphology according to claim 1, wherein The silicon source includes any one of tetraethoxysilane and tetramethoxysilane.

4. The method for preparing the silica nanoparticles with controllable morphology according to claim 1, characterized in that, The alcohol organic solvent includes any one of ethanol and methanol.

5. The method for preparing silica nanoparticles with controllable morphology according to claim 1, characterized in that, The content of metal impurities in the silicon oxide nanoparticles is less than 1 ppm, the average DLS particle size is 10-100 nm, and the particle association degree is 1-3.

6. The method for preparing the silica nanoparticles with controllable morphology according to claim 5, wherein, The morphology of the silicon oxide nanoparticles includes spherical and peanut shapes.

7. Application of a silicon oxide nanoparticle with controllable morphology as described in claims 1-6 in semiconductor preparation.

8. Use of a high-purity silica nanoparticle with controllable morphology according to claim 7, characterized in that, The application includes the rough polishing stage and the fine polishing stage in semiconductor chemical mechanical polishing.

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