Chemical mechanical polishing solution for improving polishing rate of silicon wafer as well as preparation and application of chemical mechanical polishing solution

Abstract

The invention relates to a chemical mechanical polishing solution for improving the polishing rate of a silicon wafer as well as preparation and application of the chemical mechanical polishing solution. The chemical mechanical polishing solution comprises a nitrogen-containing organic matter with the HOMO-LUMO difference value of-8.00 eV or above. The silicon wafer is chemically and mechanically polished by adding the polishing solution of the nitrogen-containing organic matter with the HOMO-LUMO difference value of-8.00 eV or above, and the polishing rate is effectively increased.

Description

Technical Field

[0001] The invention belongs to the field of polishing liquid, and particularly relates to a chemical mechanical polishing liquid for improving the polishing rate of silicon wafers and a preparation method and application thereof. Background Art

[0002] With the development of the integrated circuit industry, advanced process technology has put forward higher requirements for the polishing efficiency of silicon wafers. Chemical Mechanical Polishing (CMP) and Double Side Chemical Mechanical Polishing (DSP) and other technologies can achieve high flatness of silicon wafers.

[0003] CMP technology is a technology that combines chemical and mechanical actions, and has the advantages of fast processing speed, high grinding quality, and reliable processing results. However, during the processing, there are many factors that affect the polishing rate of silicon wafers, including the type of material on the workpiece surface, the composition of the polishing liquid, the pressure of the polishing head, etc., which makes it difficult to directly and effectively improve the polishing rate of silicon wafers. Therefore, a technical solution that can effectively improve the chemical mechanical polishing rate of silicon wafers is needed. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a chemical mechanical polishing liquid for improving the polishing rate of silicon wafers and its preparation and application.

[0005] The invention provides a chemical mechanical polishing liquid, which comprises nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV.

[0006] The raw material components of the chemical mechanical polishing liquid include nitrogen-containing organic matter with a difference (HOMO-LUMO Gap) between the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO) of more than -8.00 eV. The polishing liquid with nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV is added to chemically mechanically polish silicon wafers, thereby effectively improving the polishing rate.

[0007] The chemical mechanical polishing liquid comprises: nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV, abrasive, alkaline compound and water; wherein the weight percentage of the nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV in the polishing liquid is 0.005-0.5%.

[0008] By weight percentage, the components include:

[0009]

[0010] Preferably, the nitrogen-containing organic matter having a HOMO-LUMO difference of more than -8.00 eV includes one or more of diethylenetriamine (-7.862 eV), triethylenetetramine (-7.716 eV), N-ethylisopropylamine (-7.695 eV), 3-dimethylaminopropylamine (-7.430 eV), imidazole (-6.966 eV), 2-imidazole-1-ethylamine (-6.777 eV), and 1-(3-aminopropyl)imidazole (-6.825 eV). It should be noted that the values ​​in brackets are HOMO-LUMO differences.

[0011] The HOMO-LUMO difference of nitrogen-containing organic matter was calculated using the DMol3 module and B3LYP functional of Materials Studio software.

[0012] The HOMO-LUMO gap refers to the difference between the highest occupied molecular orbital (HOMO) and the lowest occupied molecular orbital (LUMO).

[0013] Preferably, the abrasive includes one or more of inorganic particles, organic particles, and organic-inorganic composite particles; wherein the inorganic particles include one or more of metal oxide particles, nitride particles, carbide particles, and diamond particles; the organic particles include one or more of polymethyl methacrylate PMMA particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles;

[0014] Preferably, the oxide particles include one or more of silicon dioxide, cerium oxide, aluminum oxide, and zirconium oxide; the nitride particles include one or two of silicon nitride and boron nitride; the carbide particles include one or two of silicon carbide and boron carbide;

[0015] More preferably, the abrasive is silicon dioxide particles among oxide particles, more preferably colloidal silicon dioxide particles.

[0016] Preferably, the abrasive is one or more of abrasive grains in the form of primary particles, abrasive grains in the form of secondary particles formed by the association of multiple primary particles, and a mixture of abrasive grains in the form of primary particles and abrasive grains in the form of secondary particles. The abrasive grains are also abrasive grains. Furthermore, the abrasive is in the form of at least a portion of the abrasive grains being secondary particles.

[0017] There is no particular restriction on the average primary particle size of abrasive grain. From the perspective of polishing rate, the average primary particle size of abrasive grain is preferably more than 20nm, more preferably more than 30nm, and particularly preferably more than 40nm. From the perspectives of aspects such as wafer surface defects and polishing liquid storage stability after polishing, the average primary particle size of abrasive grain is preferably below 100nm, more preferably below 80nm, and further preferably below 70nm. The average primary particle size of abrasive grain can be measured by, for example, the BET method, for example, the Flow Sorb II 2300 specific surface area measuring instrument developed by Micromeritics Instrument Corporation can be used.

[0018] There is no particular restriction on the average secondary particle size of abrasive particles. From the perspective of polishing rate, the average secondary particle size of abrasive particles is preferably more than 40nm, more preferably more than 50nm, and particularly preferably more than 60nm. From the perspectives of wafer surface defects after polishing and the storage stability of polishing liquid, the average secondary particle size of abrasive particles is preferably less than 200nm, more preferably less than 180nm, and further preferably less than 160nm. The average secondary particle size of abrasive particles can be measured by, for example, dynamic light scattering, for example, the Zetasizer Lab nanoparticle size analyzer developed by Malvern Panalytical can be used.

[0019] The alkaline compound plays a role in adjusting the pH value of the polishing liquid.

[0020] Preferably, the alkaline compound includes one or more of alkali metal hydroxides, carbonates, bicarbonates, nitrogen-containing organic alkaline compounds, and nitrogen-containing inorganic alkaline compounds.

[0021] Furthermore, the alkaline compound includes one or more of ammonia water, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and potassium carbonate.

[0022] The water plays a role in dissolving and carrying other components of the polishing liquid. The water includes one or more of ion exchange water (deionized water), pure water, ultrapure water, distilled water, etc.

[0023] Preferably, the components further include one or more of water-soluble polymers, chelating agents, surfactants, preservatives, and mildew inhibitors.

[0024] The water-soluble polymer plays a role in improving both the roughness and the flatness of the surface of the polishing object.

[0025] Preferably, the water-soluble polymer comprises one or more of vinyl alcohol polymers and cellulose derivatives; wherein the weight percentage of the water-soluble polymer is 0.005% to 0.5%, and the weight average molecular weight of the vinyl alcohol polymer is in the range of 1×103 -2×10 5 g / mol, the weight average molecular weight range of cellulose derivatives is 1×10 5 -1.5×10 6 g / mol.

[0026] The vinyl alcohol polymer includes one or more of polyvinyl alcohol, polyethylene glycol, polyvinyl acetate, polyacrylate, polyvinyl sulfonic acid, etc. The cellulose derivative includes one or more of hydroxyethyl cellulose, carboxymethyl cellulose, etc.

[0027] The chelating agent forms a complex with the metal impurities in the polishing liquid to capture the metal impurities, thereby playing a role in inhibiting the metal impurities from contaminating the polishing object.

[0028] Preferably, the chelating agent comprises one or more of carboxylic acid, organic phosphonic acid and organic sulfonic acid chelating agents, wherein the weight percentage of the chelating agent is 0.0005% to 0.1%.

[0029] The carboxylic acid chelating agent includes one or more of ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, polyacrylic acid, polymethacrylic acid, hydrolyzed polymaleic anhydride, etc. The organic phosphonic acid chelating agent includes 2-aminoethylphosphonic acid, aminotrimethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, triethylenetetraaminehexamethylphosphonic acid, hydroxyethyl-1,1-diphosphonic acid, etc. The organic sulfonic acid chelating agent includes one or more of ethylenediaminetetramethylenesulfonic acid, aminoethanesulfonic acid, aminopropanesulfonic acid, etc.

[0030] The surfactant plays a role in improving the stability of the polishing solution and optimizing the surface defects and surface roughness of the silicon wafer after polishing.

[0031] Preferably, the surfactant includes one or more of a nonionic surfactant, a cationic surfactant, and an anionic surfactant; wherein the weight percentage of the surfactant is 0.0001% to 0.1%.

[0032] Further preferably, the surfactant comprises one or more of alkyl betaine, alkyl amine oxide, polyoxyethylene alkyl ether, polyoxyethylene alkylamine, alkyl alkanolamide, polyoxyethylene fatty acid ester, sorbitan fatty acid ester and the like.

[0033] The preservative and mildew preventer play a role in maintaining the effectiveness and stability of the polishing liquid, and can be used alone or in combination.

[0034] The preservatives and mildew preventers include isothiazolin compounds, paraoxybenzoic acid esters, parahydroxybenzoic acid esters, etc. Preferred preservatives and mildew preventers include 1,2-benzisothiazolin-3-one, 2-methyl-4-isothiazolin-3-one, etc.

[0035] Preferably, the weight percentage of the preservative is 0.001% to 0.1%; the weight percentage of the mildew inhibitor is 0.001% to 0.1%.

[0036] The present invention provides a method for preparing a chemical mechanical polishing liquid. The manufacturing method is not particularly limited, and the components of the polishing liquid can be mixed by stirring, ultrasonic dispersion, homogeneous mixing, etc. There is no particular restriction on the mixing order of these components. For example, all the components can be mixed at one time, or they can be mixed in a set order. From the perspective of preparing a chemical mechanical polishing liquid with better stability, the preferred preparation method is: preferentially mix abrasive slurry, alkaline compounds and water, adjust the pH to 10-12, and then add nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV (selectively add water-soluble polymers, chelating agents, preservatives and mildew inhibitors, etc.), and stir and mix evenly.

[0037] The invention provides a method for preparing a chemical mechanical polishing liquid, comprising: mixing raw materials to obtain.

[0038] The polishing liquid is diluted with deionized water with a mass of 10-50 times when used.

[0039] The invention provides an application of the chemical mechanical polishing liquid in polishing silicon wafers.

[0040] Beneficial Effects

[0041] The chemical mechanical polishing liquid of the invention can effectively improve the polishing rate of silicon wafers. DETAILED DESCRIPTION

[0042] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0043] It should be noted that the process equipment or devices not specifically specified in the following examples are all conventional equipment or devices in the art. In addition, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below, and one or more method steps mentioned in the present invention do not exclude the presence of other method steps before and after the combination step or the insertion of other method steps between these explicitly mentioned steps, unless otherwise specified. It should also be understood that the terms used in the examples of the present invention are intended to describe specific embodiments, not to limit the scope of protection of the present invention. The test methods for which specific conditions are not specified in the following examples are generally carried out under conventional conditions or under the conditions recommended by the manufacturers.

[0044] In the following embodiments of the present application, a specific polishing process condition is adopted, specifically:

[0045] Polishing object: 300mm diameter (100) surface silicon wafer;

[0046] Polishing equipment: Tianjin Huahai Qingke Universal-300X;

[0047] Polishing pad: Polyurethane polishing pad SPM-3100 manufactured by NITTA DuPont, Japan;

[0048] Polishing speed ratio: 123:119rpm;

[0049] Polishing liquid flow rate: 300mL / min;

[0050] Polishing pressure: 3.0psi.

[0051] Example 1

[0052] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0053] 35% by mass of colloidal silica (average secondary particle size 110 nm), 1.6% by mass of tetramethylammonium hydroxide (TMAH), 1% by mass of potassium carbonate, 0.3% by mass of diethylenetriamine and ion exchange water were stirred and mixed at room temperature (25°C) for 30 minutes to obtain a polishing liquid.

[0054] The polishing liquid obtained by the above process needs to be diluted by 30 times by mass and added with ion exchange water for polishing experiments.

[0055] The chemical structure of diethylenetriamine is

[0056] Example 2

[0057] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps: replacing the diethylenetriamine in Embodiment 1 with triethylenetetramine, and the rest of the components are completely the same as those in Embodiment 1.

[0058] The chemical structure of triethylenetetramine is

[0059] Example 3

[0060] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps: replacing the diethylenetriamine in Example 1 with N-ethylisopropylamine, and the rest of the steps are completely the same as those in Example 1.

[0061] Chemical structure of N-ethylisopropylamine

[0062] Example 4

[0063] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps: replacing the diethylenetriamine in Example 1 with 3-dimethylaminopropylamine, and the rest of the steps are completely the same as those in Example 1.

[0064] Chemical structure of 3-dimethylaminopropylamine

[0065] Example 5

[0066] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps: using imidazole to replace the diethylenetriamine in Embodiment 1, and the rest of the steps are completely the same as those in Embodiment 1.

[0067] The chemical structure of imidazole

[0068] Example 6

[0069] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps: replacing the diethylenetriamine in Example 1 with 2-imidazole-1-ethylamine, and the rest of the steps are completely the same as those in Example 1.

[0070] Chemical structure of 2-imidazole-1-ethylamine

[0071] Example 7

[0072] In this embodiment, a method for preparing a novel chemical mechanical polishing liquid is provided, comprising the following steps:

[0073] The diethylenetriamine in Example 1 was replaced by 1-(3-aminopropyl)imidazole, and the rest of the parts were completely the same as those in Example 1.

[0074] Chemical structure of 1-(3-aminopropyl)imidazole

[0075] Comparative Example 1

[0076] The difference between this comparative example and Example 1 is that: no nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV is used, that is, no diethylenetriamine is used; the rest of the parts are completely the same as Example 1.

[0077] Comparative Example 2

[0078] The difference between this comparative example and Example 1 is that isobutylamine is used to replace the diethylenetriamine in Example 1; the rest of the parts are completely the same as Example 1.

[0079] Chemical structure of isobutylamine

[0080] Comparative Example 3

[0081] The difference between this comparative example and Example 1 is that 2-methylbutylamine is used to replace the diethylenetriamine in Example 1; the rest of the parts are completely the same as Example 1.

[0082] Chemical structure of 2-methylbutylamine

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 1 is that n-propylamine is used to replace the diethylenetriamine in Example 1; the rest of the parts are completely the same as Example 1.

[0085] Chemical structure of n-propylamine

[0086] The performance of CMP (Chemical Mechanical Polishing) polishing fluid is generally evaluated by measuring the polishing rate of silicon wafers. The polishing rate is measured using a die geometry metrology system (WaferSight2+, KLA Tencor, Milpitas, CA, USA). The polishing rate is calculated by measuring the mass difference before and after polishing of the silicon wafer and dividing it by the polishing time.

[0087] The polishing rate of the chemical mechanical polishing liquid obtained in Examples 1-7 and Comparative Examples 1-4 was tested, and the specific operation was: the quality of the silicon wafer was measured before and after polishing, and the polishing rate was calculated by dividing the quality difference before and after polishing of the silicon wafer by the polishing time.

[0088] The polishing rate test results are shown in Table 1. The polishing rates of the examples in Table 1 are calculated relative to the polishing rate of Comparative Example 1 (590 nm / min), and a larger value indicates a higher polishing rate.

[0089] Table 1

[0090]

[0091]

[0092] It can be seen from Table 1 that the chemical mechanical polishing liquid obtained by the preparation method of the present application can achieve a polishing rate value higher than that of the comparative polishing liquid, which indicates that the chemical mechanical polishing liquid provided by the present application containing nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV can significantly improve the polishing rate of silicon wafers for IGBT.

Claims

1. A chemical mechanical polishing liquid, characterized in that: The polishing liquid includes nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV.

2. The chemical mechanical polishing solution according to claim 1, characterized in that: By weight percentage, the components include: 0.005-0.5% of nitrogen-containing organic matter with a HOMO-LUMO difference above -8.00 eV; Abrasive 1-40%; Basic compounds 0.01-10%; Water 50~98.9%.

3. The chemical mechanical polishing solution according to claim 1 or 2, characterized in that: The nitrogen-containing organic matter with a HOMO-LUMO difference of more than -8.00 eV includes one or more of diethylenetriamine, triethylenetetramine, N-ethylisopropylamine, 3-dimethylaminopropylamine, imidazole, 2-imidazole-1-ethylamine, and 1-(3-aminopropyl)imidazole.

4. The chemical mechanical polishing solution according to claim 2, characterized in that: The abrasive includes one or more of inorganic particles, organic particles, and organic-inorganic composite particles; wherein the inorganic particles include one or more of metal oxide particles, nitride particles, carbide particles, and diamond particles; the organic particles include one or more of polymethyl methacrylate PMMA particles, poly (meth) acrylic acid particles, and polyacrylonitrile particles; The alkaline compound includes one or more of alkali metal hydroxides, carbonates, bicarbonates, nitrogen-containing organic alkaline compounds, and nitrogen-containing inorganic alkaline compounds.

5. The chemical mechanical polishing liquid according to claim 4, characterized in that: The oxide particles include one or more of silicon dioxide, cerium oxide, aluminum oxide, and zirconium oxide; the nitride particles include one or two of silicon nitride and boron nitride; the carbide particles include one or two of silicon carbide and boron carbide; The alkaline compound includes one or more of ammonia water, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide and potassium carbonate.

6. The chemical mechanical polishing solution according to claim 2, characterized in that: The abrasive is one or more of abrasive grains in the form of primary particles, abrasive grains in the form of secondary particles, or a mixture of abrasive grains in the form of primary particles and abrasive grains in the form of secondary particles; The average primary particle size of the abrasive is greater than 20 nm; the average secondary particle size of the abrasive is greater than 40 nm.

7. The chemical mechanical polishing solution according to claim 2, characterized in that: The components also include one or more of water-soluble polymers, chelating agents, surfactants, preservatives, and mildew inhibitors.

8. The chemical mechanical polishing solution according to claim 7, characterized in that: The water-soluble polymer includes one or more of vinyl alcohol polymers and cellulose derivatives; wherein the weight percentage of the water-soluble polymer is 0.005% to 0.5%; The chelating agent includes one or more of carboxylic acid, organic phosphonic acid, and organic sulfonic acid chelating agents, wherein the weight percentage of the chelating agent is 0.0005% to 0.1%; The surfactant includes one or more of a nonionic surfactant, a cationic surfactant, and an anionic surfactant; wherein the weight percentage of the surfactant is 0.0001% to 0.1%; The weight percentage of the preservative is 0.001% to 0.1%; the weight percentage of the mildew inhibitor is 0.001% to 0.1%.

9. A method for preparing a chemical mechanical polishing liquid, comprising: The raw materials are mixed to obtain.

10. Use of the chemical mechanical polishing liquid according to claim 1 in polishing silicon wafers.

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