Analysis method for morphology of abrasive particles in polishing solution and polishing method

Abstract

The invention provides an analysis method for morphology of abrasive particles in a polishing solution and a polishing method.The analysis method comprises the following steps that the polishing solution is provided, and the polishing solution at least comprises the abrasive particles and an oxidizing agent; adjusting the pH value of the polishing solution to be neutral, and mixing the polishing solution with a solvent to obtain a first sample to be detected; enabling the first to-be-tested sample to be in contact with the surface of a substrate material, and obtaining a second test sample after the first to-be-tested sample is air-dried; and testing the morphology of the abrasive particles in the second test sample through SEM. Whether the abrasive particles in the polishing solution are in contact reaction with the oxidizing agent, the dispersing agent or other auxiliaries in the polishing solution or not is judged through a simple analysis method, so that the state of the abrasive particles is influenced, and the polishing effect is further influenced.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor chemical mechanical polishing, in particular to an analysis method for abrasive particle morphology in a polishing liquid and a polishing method. Background Art

[0002] The rapid development of the semiconductor industry, driven by shrinking device sizes and the reduced depth of focus of optical lithography equipment, requires silicon wafer surfaces to achieve acceptable resolution and flatness at the nanometer level. Chemical Mechanical Polishing (CMP) is a technique that flattens metal and dielectric layers, enabling multi-layer metal interconnects. CMP combines the mechanical abrasive action of nanoscale particles with the chemical etching action of oxidants to perform ultra-fine processing on silicon wafers, achieving a smooth, flat surface topography unattainable by other planarization technologies.

[0003] Abrasive performance is a key factor in CMP technology, directly influencing various indicators of chemical mechanical polishing, including polishing rate, polishing selectivity, and damage to the polished material. With the continued advancement of abrasive research, a growing number of polishing slurries with varying compositions have entered the market to meet increasingly sophisticated polishing requirements. During the preparation of polishing slurries, abrasive particles inevitably interact with the oxidants, dispersants, and polishing aids in the slurry. The abrasive's inherent state significantly impacts the flatness of the polished silicon wafer. Therefore, analysis of abrasive particles in finished polishing slurries is crucial. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a method for analyzing the morphology of abrasive particles in a polishing liquid and a polishing method, so as to solve the problems in the prior art.

[0005] To achieve the above-mentioned purpose and other related purposes, the present invention is achieved through the following technical solutions.

[0006] The present invention provides a method for analyzing the morphology of abrasive particles in a polishing liquid, comprising the following steps:

[0007] Providing a polishing liquid, wherein the polishing liquid includes at least abrasive particles and an oxidant; adjusting the pH of the polishing liquid to neutral, and mixing it with a solvent to obtain a first sample to be tested;

[0008] placing the first test sample in contact with the surface of a substrate material, and obtaining a second test sample after the first test sample is air-dried;

[0009] The morphology of the abrasive particles in the second test sample was measured by SEM.

[0010] Preferably, the average diameter of the abrasive particles in the polishing solution is 50-500nm. For example, it can be 50-100nm, 100-200nm, 200-300nm, 300-400nm, 400-500nm.

[0011] Preferably, the abrasive particles in the polishing solution are spherical.

[0012] Preferably, the abrasive particles are silica particles.

[0013] Preferably, the pH adjusting agent is selected from diethanolamine and / or acetic acid. Adjusting the pH of the polishing solution reduces the cross-linking of the abrasive particles with each other during air drying.

[0014] Preferably, the solvent is ethanol. The solvent dissolves the organic agents in the polishing solution and evaporates part of the liquid in the polishing solution during subsequent air drying.

[0015] Preferably, the volume ratio of the polishing solution to the solvent in the first test sample is 1:(8-15). For example, it can be 1:(8-9), 1:(9-10), 1:(10-11), 1:(11-12), 1:(12-13), 1:(14-15).

[0016] Preferably, the substrate material is pretreated before use. The pretreatment method is to wash the substrate material with water and ethanol and then dry the substrate material. Pretreating the substrate material removes particulate matter on the surface of the substrate material and improves the cleanliness of the surface of the substrate material.

[0017] Preferably, the substrate material is selected from a silicon wafer or a glass wafer.

[0018] Preferably, the mixing is performed using ultrasonic treatment. Ultrasonic treatment disperses the abrasive particles in the solvent and reduces agglomeration.

[0019] Preferably, the air drying time is 24-48h. For example, the air drying time can be 24h, 36h, or 48h.

[0020] The application also discloses a polishing method for a semiconductor substrate, which uses the analysis method described above to select a polishing solution for polishing the semiconductor substrate.

[0021] Preferably, the polishing solution is selected based on the SEM test results of the second test sample, in which the abrasive particles are spherical.

[0022] The application discloses an analysis method for the morphology of abrasive particles in a polishing solution and a polishing method. The method can determine whether the abrasive particles in the polishing solution will react with oxidizing agents, dispersants or other additives in the polishing solution, thereby affecting the state of the abrasive particles and further affecting the polishing effect. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 SEM spectrum of the abrasive particles obtained in Example 1 is shown.

[0024] Figure 2 SEM spectrum of the abrasive particles obtained in Comparative Example 1 is shown.

[0025] Figure 3 SEM spectrum of the abrasive particles obtained in Comparative Example 2 is shown.

[0026] Figure 4 SEM spectrum of the abrasive particles obtained in Comparative Example 3 is shown. DETAILED DESCRIPTION

[0027] The present application can be further understood by the following detailed description of particular embodiments, especially when taken in conjunction with the claims and drawings where:

[0028] It should be noted that the process equipment or apparatus not specifically mentioned in the following examples are all conventional equipment or apparatus in the art.

[0029] It should also be understood that the one or more method steps mentioned in the present application do not exclude the presence of other method steps before and after the mentioned combination steps or the insertion of other method steps between the explicitly mentioned steps, unless otherwise specified; and, unless otherwise specified, the numbering of the method steps is only a convenient tool for identifying the method steps and is not intended to limit the arrangement order of the method steps or to limit the scope of the application, and the change or adjustment of the relative relationship, without substantial change of the technical content, is also considered as the scope of the application.

[0030] The polishing liquid used in the examples of the present application is JZA-S150N.

[0031] The abrasive particles in the polishing liquid are silicon dioxide, the average particle size of the abrasive particles is 100 nm, and the morphology of the abrasive particles is spherical.

[0032] Example 1

[0033] The present example provides a specific method for analyzing the morphology of abrasive particles in a polishing liquid, and the specific steps are as follows:

[0034] 1. Preparation of base material

[0035] (1) A silicon wafer of approximately 3 cm x 3 cm in size is cut using a silicon wafer knife;

[0036] (2) The cut silicon wafer is cleaned with pure water, then placed in a 50ml beaker, and an appropriate amount of ethanol is added to cover the silicon wafer. The silicon wafer is ultrasonically cleaned for 30 minutes by using a 35KHZ standard frequency ultrasonic cleaner. After cleaning, the silicon wafer is taken out.

[0037] (3) The silicon wafer is transferred to a wide-mouth bottle filled with ethanol for storage.

[0038] 2. Polishing liquid treatment

[0039] (1) 10mL of the polishing liquid sample is taken in a beaker, and diethanolamine is added to adjust the polishing liquid sample to neutral.

[0040] (2) 1mL of the polishing liquid sample is taken into a 10mL volumetric flask, and ethanol is added to constant volume. Then, the sample is transferred to a 35KHZ standard frequency ultrasonic cleaner for ultrasonic cleaning for 30 minutes to obtain a first test sample.

[0041] 3. Morphology observation

[0042] (1) The cleaned silicon wafer is taken out and placed in a watch glass, and the surface ethanol is allowed to volatilize completely.

[0043] (2) 2-3 drops of the first test sample are dropped onto the surface of the silicon wafer, and the sample is allowed to air dry at a ventilated place for 24 hours to obtain a second test sample.

[0044] (3) The morphology of the abrasive particles in the second test sample is observed by scanning electron microscopy, and the SEM image is shown in Figure 1 .

[0045] As can be seen from Figure 1 , the abrasive particles in the second test sample have good dispersibility and do not agglomerate or crosslink. The shape of the abrasive particles can be clearly distinguished as spherical. The polishing liquid can be used for polishing semiconductor substrates.

[0046] Comparative Example 1

[0047] This comparative example is a comparative example of Example 1, and provides a specific method for analyzing the morphology of abrasive particles in a polishing liquid. The specific steps are as follows:

[0048] 1. Preparation of base material

[0049] (1) A silicon wafer with a size of about 3cm x 3cm is cut by using a silicon wafer knife.

[0050] (2) The cut silicon wafer is cleaned with pure water, then placed in a 50ml beaker, and an appropriate amount of ethanol is added to cover the silicon wafer. The silicon wafer is ultrasonically cleaned for 30 minutes by using a 35KHZ standard frequency ultrasonic cleaner. After cleaning, the silicon wafer is taken out.

[0051] (3) The silicon wafer is transferred to a wide-mouth bottle filled with ethanol for storage.

[0052] 2. Morphology observation

[0053] (1) The cleaned silicon wafer was taken out and placed in a surface dish, and the surface ethanol was allowed to evaporate completely;

[0054] (2) 2-3 drops of the polishing liquid were taken and dropped onto the surface of the silicon wafer, and the silicon wafer was left to air dry for 24 h in a ventilated place;

[0055] (3) The air-dried silicon wafer was observed for morphology using a scanning electron microscope, and the SEM spectrum is shown in Figure 2 .

[0056] From Figure 2 it can be seen that a large number of adjacent abrasive particles are cross-linked, and it cannot be determined whether the shape of the abrasive particles in the polishing liquid is changed from spherical to other shapes, so that it cannot be determined whether the polishing liquid can be used for polishing semiconductor substrates.

[0057] Comparative Example 2

[0058] This comparative example is a comparative example of Example 1, and provides a specific method for analyzing the morphology of abrasive particles in a polishing liquid, and the specific steps are as follows:

[0059] 1. Preparation of base material

[0060] (1) A silicon wafer with a size of about 3 cm x 3 cm was cut using a silicon wafer knife;

[0061] (2) The cut silicon wafer was cleaned with pure water and then placed in a 50 ml beaker, and an appropriate amount of ethanol was added to cover the silicon wafer. A 35 KHZ standard frequency ultrasonic cleaner was used to ultrasonically clean the silicon wafer for 30 min, and after washing, the silicon wafer was taken out.

[0062] (3) The silicon wafer was transferred to a wide-mouth bottle filled with ethanol for storage.

[0063] 2. Polishing liquid treatment

[0064] 10 mL of the polishing liquid sample was taken in a beaker, and diethanolamine was added to adjust the polishing liquid sample to neutral.

[0065] 3. Morphology observation

[0066] (1) The cleaned silicon wafer was taken out and placed in a surface dish, and the surface ethanol was allowed to evaporate completely;

[0067] (2) 2-3 drops of the polishing liquid sample adjusted to neutral were taken and dropped onto the surface of the silicon wafer, and the silicon wafer was left to air dry for 24 h in a ventilated place;

[0068] (3) The air-dried silicon wafer was observed for morphology using a scanning electron microscope, and the SEM spectrum is shown in Figure 3 .

[0069] From Figure 3It can be seen that the abrasive particles in the polishing liquid sample adjusted to neutral have agglomerated, and it is not possible to determine whether the shape of the abrasive particles has changed from spherical to other shapes, and thus it is not possible to determine whether the polishing liquid can be used for polishing semiconductor substrates.

[0070] Comparative Example 3

[0071] This comparative example is a comparative example of Example 1, and provides a specific method for analyzing the morphology of abrasive particles in a polishing liquid. The specific steps are as follows:

[0072] 1. Preparation of base material

[0073] (1) A silicon wafer of approximately 3 cm x 3 cm in size is cut using a silicon wafer cutter;

[0074] (2) The cut silicon wafer is washed with pure water and then placed in a 50 ml beaker. An appropriate amount of ethanol is added to cover the silicon wafer, and the silicon wafer is ultrasonically cleaned for 30 minutes using a 35 KHZ standard frequency ultrasonic cleaner. After washing, the silicon wafer is removed;

[0075] (3) The silicon wafer is transferred to a wide-mouth bottle filled with ethanol for storage.

[0076] 2. Polishing liquid treatment

[0077] (1) 10 mL of the polishing liquid sample is taken in a beaker, and diethanolamine is added to adjust the polishing liquid sample to neutral;

[0078] (2) 1 mL of the polishing liquid sample is taken into a 10 mL volumetric flask, and ethanol is added to constant volume. Then, it is transferred to a 35 KHZ standard frequency ultrasonic cleaner for ultrasonic cleaning for 30 minutes to obtain a first test sample.

[0079] 4. Morphology observation

[0080] (1) The cleaned silicon wafer is removed and placed in a watch glass, and the surface ethanol is allowed to evaporate completely;

[0081] (2) 2-3 drops of the first test sample are taken and dropped onto the surface of the silicon wafer. It is allowed to stand in a well-ventilated place for 72 hours for air drying to obtain a second test sample;

[0082] (3) The morphology of the abrasive particles in the second test sample is observed by scanning electron microscopy, and the SEM spectrum is shown in Figure 4 .

[0083] From Figure 4 it can be seen that the surface of the abrasive particles in the second test sample is uneven, and it is not possible to determine whether the shape of the abrasive particles has changed from spherical to other shapes, and thus it is not possible to determine whether the polishing liquid can be used for polishing semiconductor substrates.

[0084] Comparative Example 4

[0085] This comparative example is a comparative example of Example 1, and provides a specific analysis method of the morphology of abrasive particles in a polishing liquid. The specific steps are as follows:

[0086] 1. Preparation of base material

[0087] (1) A silicon wafer of approximately 3 cm x 3 cm in size was cut using a silicon wafer cutter;

[0088] (2) The cut silicon wafer was washed with pure water and then placed in a 50 ml beaker. An appropriate amount of ethanol was added to cover the silicon wafer, and the silicon wafer was ultrasonically cleaned for 30 minutes using a 35 KHZ standard frequency ultrasonic cleaner. After washing, the silicon wafer was removed;

[0089] (3) The silicon wafer was transferred to a wide-mouth bottle filled with ethanol for storage.

[0090] 2. Polishing liquid treatment

[0091] (1) 10 mL of the polishing liquid sample was taken in a beaker, and diethanolamine was added to adjust the polishing liquid sample to neutral;

[0092] (2) 1 mL of the polishing liquid sample was taken into a 5 mL volumetric flask, and ethanol was added to constant volume. Then, it was transferred to a 35 KHZ standard frequency ultrasonic cleaner for ultrasonic cleaning for 30 minutes to obtain a first test sample.

[0093] 3. Morphology observation

[0094] (1) The cleaned silicon wafer was taken out and placed in a watch glass, and the surface ethanol was allowed to evaporate completely;

[0095] (2) 2-3 drops of the first test sample were taken and dropped onto the surface of the silicon wafer. It was placed in a well-ventilated place for 24 hours for air drying to obtain a second test sample;

[0096] (3) The morphology of the abrasive particles in the second test sample was observed by scanning electron microscopy.

[0097] The second test sample was observed by scanning electron microscopy, and it was found that the abrasive particles were too dispersed, making it inconvenient to observe the morphology of a large number of abrasive particles.

[0098] Comparative Example 5

[0099] This comparative example is a comparative example of Example 1, and provides a specific analysis method of the morphology of abrasive particles in a polishing liquid. The specific steps are as follows:

[0100] 1. Preparation of base material

[0101] (1) A silicon wafer of approximately 3 cm x 3 cm in size was cut using a silicon wafer cutter;

[0102] (2) The cut silicon wafer is cleaned with pure water and then placed in a 50ml beaker, and an appropriate amount of ethanol is added to cover the silicon wafer. The silicon wafer is ultrasonically cleaned for 30 minutes by using a 35KHZ standard frequency ultrasonic cleaner. After cleaning, the silicon wafer is taken out;

[0103] (3) The silicon wafer is transferred to a wide-mouth bottle filled with ethanol for storage.

[0104] 2. Polishing liquid treatment

[0105] (1) 10mL of the polishing liquid sample is taken in a beaker, and diethanolamine is added to adjust the polishing liquid sample to neutral;

[0106] (2) 1mL of the polishing liquid sample is taken in a sample bottle, diluted with 20mL of ethanol, and then transferred to a 35KHZ standard frequency ultrasonic cleaner for ultrasonic cleaning for 30 minutes to obtain a first test sample.

[0107] 3. Morphology observation

[0108] (1) The cleaned silicon wafer is taken out and placed in a surface dish, and the surface ethanol is allowed to volatilize completely;

[0109] (2) 2-3 drops of the treated polishing liquid sample are dropped onto the surface of the silicon wafer, and the sample is placed in a ventilated place for 24 hours for air drying to obtain a second test sample;

[0110] (3) The morphology of the abrasive grains in the second test sample is observed by scanning electron microscopy.

[0111] The second test sample is observed by scanning electron microscopy, and it is found that the agglomeration between adjacent abrasive grains is obvious, and the shape of the abrasive grains cannot be distinguished whether it is changed from spherical to other shapes, so that it cannot be judged whether the polishing liquid can be used for polishing semiconductor substrates.

[0112] The above examples only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above examples without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought disclosed by the present application should be covered by the claims of the present application.

Claims

1. A method of analyzing the morphology of abrasive particles in a polishing liquid, characterized by, The method comprises the following steps: providing a polishing liquid comprising at least abrasive particles and an oxidizing agent; mixing the polishing liquid with a solvent to obtain a first test sample after adjusting the pH of the polishing liquid to neutral; contacting the first test sample with a surface of a substrate material to obtain a second test sample after air-drying the first test sample; testing the morphology of the abrasive particles in the second test sample by SEM.

2. The analysis method according to claim 1, characterized in that, The average diameter of the abrasive particles in the polishing liquid is 50-500 nm; and / or the abrasive particles in the polishing liquid are spherical.

3. The analysis method of claim 1, wherein, The reagent for adjusting the pH is selected from diethanolamine and / or acetic acid; and / or the abrasive particles are silica particles.

4. The analysis method of claim 1, wherein, The solvent is ethanol.

5. The analysis method of claim 1, wherein, The volume ratio of the polishing liquid to the solvent in the first test sample is 1:(8-15).

6. The analysis method of claim 1, wherein, The substrate material is pretreated before use, and the pretreatment method is washing the substrate material with water and ethanol and then drying.

7. The analysis method of claim 1, wherein, The substrate material is selected from a silicon wafer or a glass sheet.

8. The analysis method of claim 1, wherein, The mixing is performed by ultrasonic treatment; and / or the air-drying time is 24-48 h.

9. A method of polishing a semiconductor substrate, comprising: The polishing liquid is selected by using the analysis method according to any one of claims 1-8 to polish a semiconductor substrate.

10. The polishing method according to claim 9, wherein The polishing liquid is selected by testing the morphology of the abrasive particles in the second test sample by SEM, and the abrasive particles are spherical.

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