Chemical mechanical polishing solution for polishing doped silicon wafer for IGBT (Insulated Gate Bipolar Translator)

Abstract

The invention relates to a chemical mechanical polishing solution for polishing a doped silicon wafer for an IGBT (Insulated Gate Bipolar Translator). The chemical mechanical polishing solution comprises a guanidyl compound, a grinding material, an alkaline compound, water and other additives. The chemical mechanical polishing solution provided by the invention can obviously improve the polishing rate of a silicon wafer for an IGBT (Insulated Gate Bipolar Translator), improves the surface smoothness, inhibits the formation of defects, prolongs the service life of the polishing solution, has good chemical stability and environmental friendliness, and provides reliable support for manufacturing efficient and low-loss silicon-based power devices.

Description

Technical Field

[0001] The invention belongs to the technical field of polishing liquids, and in particular relates to a chemical mechanical polishing liquid for polishing doped silicon wafers for IGBTs. Background Art

[0002] With the rapid development of the integrated circuit industry, advanced manufacturing processes have placed higher demands on the processing of various semiconductor materials. Among these, the surface quality and processing efficiency of silicon wafers used in insulated-gate bipolar transistors (IGBTs), the core material of power devices, directly impact device performance and production costs. Therefore, improving the polishing efficiency of IGBT silicon wafers has become a key research area in semiconductor manufacturing.

[0003] Advanced processing technologies such as Chemical Mechanical Polishing (CMP) and Double Side Polishing (DSP) can achieve a high degree of flatness on the surface of silicon wafers and meet high-precision process requirements. CMP technology combines the dual effects of chemical reaction and mechanical grinding to ensure the thickness uniformity and defect control of silicon wafers while improving surface smoothness. However, in the polishing process of silicon wafers for IGBTs, the polishing rate is affected by multiple factors, such as the crystal orientation of the silicon material, the chemical composition of the polishing liquid, the characteristics of the polishing pad, the polishing pressure and the rotation rate. The interaction of these variables makes it difficult to directly improve processing efficiency by relying solely on traditional CMP processes.

[0004] Therefore, in order to meet the demand for efficient processing of silicon wafers for IGBT, a technical solution is needed that can effectively improve the chemical mechanical polishing rate of silicon wafers. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a chemical mechanical polishing liquid for polishing doped silicon wafers for IGBT, which can significantly improve the polishing rate of silicon wafers for IGBT and has good application prospects.

[0006] The invention provides a chemical mechanical polishing liquid for polishing doped silicon wafers for IGBT, which is characterized by comprising a guanidine compound, abrasives, alkaline compounds, water and other additives.

[0007] Preferably, the guanidine compound includes one or more of arginine, guanidine acetic acid, 4-guanidine benzoic acid, guanidine propionic acid, and guanidine valeric acid; and the mass percentage concentration of the guanidine compound is 0.005 to 0.5%.

[0008] Preferably, the abrasive includes one or more of inorganic particles, organic particles, and organic-inorganic composite particles; and the mass percentage concentration of the abrasive is 1 to 40%.

[0009] 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.

[0010] The metal oxide particles include one or more of silicon dioxide, cerium oxide, aluminum oxide, and zirconium oxide; the nitride particles include one or both of silicon nitride and boron nitride; and the carbide particles include one or both of silicon carbide and boron carbide. Preferably, the abrasive is silicon dioxide particles among the metal oxide particles. More preferably, the abrasive is colloidal silica particles.

[0011] The abrasive may be in the form of primary particles or in the form of secondary particles formed by the association of multiple primary particles. Alternatively, it may be a mixture of abrasive particles in the form of primary particles and abrasive particles in the form of secondary particles. Preferably, the abrasive is one in which at least a portion of the abrasive particles are in the form of secondary particles.

[0012] There are no particular restrictions for the average primary particle size of abrasive particle. From the perspective of polishing rate, the average primary particle size of abrasive grain is preferably more than the 20nm, more preferably more than the 30nm, and particularly preferably more than the 40nm. From the perspectives of aspects such as wafer surface defects and polishing fluid storage stability after polishing, the average primary particle size of abrasive particle is preferably below the 100nm, more preferably below the 80nm, further preferably below the 70nm. The average primary particle size of abrasive particle 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.

[0013] There are no particular restrictions on the average secondary particle size of abrasive grain. From the perspective of polishing rate, the average secondary particle size of abrasive grain is preferably more than 40nm, more preferably more than 50nm, and particularly preferably more than 60nm. From the perspectives of aspects such as wafer surface defects and polishing liquid storage stability after polishing, the average secondary particle size of abrasive grain is preferably below 200nm, more preferably below 180nm, and further preferably below 160nm. The average secondary particle size of abrasive grain can be measured by, for example, dynamic light scattering, for example, the Zetasizer Lab nanoparticle size analyzer developed by Malvern Panalytical can be used.

[0014] Preferably, the alkaline compound includes one or more of alkali metal hydroxides, carbonates, bicarbonates, and nitrogen-containing organic or inorganic alkaline compounds; the mass percentage concentration of the alkaline compound is 0.01 to 10%. The alkaline compound plays a role in adjusting the pH value of the polishing liquid.

[0015] Preferably, the alkaline compound is one or more of ammonia water, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and potassium carbonate.

[0016] Preferably, the water includes one or more of deionized water, pure water, ultrapure water, and distilled water, and the mass percentage concentration of the water is 50-99%. The water plays the role of dissolving and carrying other components of the polishing liquid.

[0017] Furthermore, the other additives include one or more of chelating agents, surfactants, preservatives, and mildew inhibitors.

[0018] Preferably, the chelating agent comprises one or more of carboxylic acids, organic phosphonic acids, and organic sulfonic acids; the mass percentage concentration of the chelating agent is 0.0005% to 0.1%. The chelating agent forms a complex with metal impurities in the polishing liquid to capture them, thereby inhibiting the metal impurities from contaminating the polishing object.

[0019] Carboxylic acid chelating agents include ethylenediaminetetraacetic acid, sodium ethylenediaminetetraacetate, nitrilotriacetic acid, ammonium nitrilotriacetate, hydroxyethylethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid, polyacrylic acid, polymethacrylic acid, and hydrolyzed polymaleic anhydride. Organic phosphonic acid chelating agents include 2-aminoethylphosphonic acid, aminotrimethylenephosphonic acid, diethylenetriaminepentamethylenephosphonic acid, ethylenediaminetetramethylenephosphonic acid, triethylenetetraaminehexamethylphosphonic acid, and hydroxyethylene-1,1-diphosphonic acid. Organic sulfonic acid chelating agents include ethylenediaminetetramethylenesulfonic acid, aminoethanesulfonic acid, and aminopropanesulfonic acid.

[0020] Preferably, the surfactant comprises one or more of a nonionic surfactant, a cationic surfactant, and an anionic surfactant, and the mass percentage concentration of the surfactant is 0.0001% to 0.1%. The surfactant improves the stability of the polishing solution and optimizes the surface defects and surface roughness of the polished silicon wafer.

[0021] More preferably, the surfactant comprises alkyl betaine, alkylamine oxide, polyoxyethylene alkyl ether, polyoxyethylene alkylamine, alkyl alkanolamide, polyoxyethylene fatty acid ester, sorbitan fatty acid ester and the like.

[0022] Preferably, the preservative and mildew inhibitor are used alone or in combination.

[0023] Preferably, the preservative or mildew preventer comprises one or more of isothiazolinone, paraoxybenzoic acid esters, and parahydroxybenzoic acid esters; and the mass percentage concentration of the preservative or mildew preventer is 0.001% to 0.1%.

[0024] There is no particular limitation on the method for producing the chemical mechanical polishing solution. For example, the components of the polishing solution can be mixed using methods such as stirring, ultrasonic dispersion, and homogeneous mixing. There is no particular limitation on the way these components are mixed. For example, all the components can be mixed at once, or they can be mixed in a set order. From the perspective of preparing a chemical mechanical polishing solution with better stability, a preferred preparation method is: preferentially mix the abrasive slurry, the alkaline compound, and water, adjust the pH to 10-12, and then add the guanidine compound, surfactant, chelating agent, preservative, and mildew inhibitor, and stir and mix evenly.

[0025] Beneficial effects

[0026] The chemical mechanical polishing liquid provided by the present invention can significantly increase the polishing rate of silicon wafers for IGBT, while improving surface smoothness, inhibiting defect formation, and extending the service life of the polishing liquid. It has good chemical stability and environmental friendliness, and provides reliable support for the manufacture of high-efficiency, low-loss silicon-based power devices. DETAILED DESCRIPTION

[0027] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, 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 equally within the scope limited by the appended claims of the application.

[0028] In the following embodiments of the present application, a specific polishing process condition is adopted, specifically:

[0029] Polishing object: 300mm diameter (100) face silicon wafer;

[0030] Polishing equipment: Tianjin Huahai Qingke Universal-300X;

[0031] Polishing pad: Polyurethane polishing pad SPM-3100 manufactured by NITTADuPont, Japan;

[0032] Polishing speed ratio: 123:119rpm;

[0033] Polishing liquid flow rate: 300mL / min;

[0034] Polishing pressure: 3.0psi.

[0035] Example 1

[0036] In this embodiment, a method for preparing a chemical mechanical polishing solution for polishing doped silicon wafers for IGBT is provided, comprising the following steps:

[0037] 35% by mass of colloidal silica (average particle size of 110 nm), 1.6% by mass of tetramethylammonium hydroxide (TMAH), 1% by mass of potassium carbonate, 0.3% by mass of arginine, and 62.1% by mass of ion-exchanged water were mixed and stirred at room temperature (25° C.) for 30 minutes to obtain a mixture.

[0038] The above mixture is a concentrated solution and needs to be diluted 30 times by mass when used.

[0039] The structural formula of the arginine is as follows:

[0040]

[0041] Example 2

[0042] In this example, guanidine acetic acid was used to replace the arginine in Example 1, and the rest of the reaction was the same as that in Example 1.

[0043] The structural formula of the guanidinoacetic acid is as follows:

[0044]

[0045] Example 3

[0046] In this example, 4-guanidinobenzoic acid was used to replace the arginine in Example 1, and the rest of the steps were the same as those in Example 1.

[0047] The structural formula of the 4-guanidinobenzoic acid is as follows:

[0048]

[0049] Example 4

[0050] In this embodiment, guanidine propionic acid was used to replace the arginine in Example 1, and the rest of the process remained the same as in Example 1.

[0051] The structural formula of the guanidinopropionic acid is as follows:

[0052]

[0053] Comparative Example 1

[0054] This comparative example differs from Example 1 in that no guanidine compound, that is, no arginine, is used. The rest of the process is identical to Example 1.

[0055] Comparative Example 2

[0056] The difference between this comparative example and Example 1 is that lysine is used instead of arginine in Example 1. The rest of the steps are the same as those in Example 1.

[0057] The structural formula of the lysine is as follows:

[0058]

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 2 is that glycine is used instead of guanidine acetic acid in Example 2. The rest of the steps are the same as those in Example 2.

[0061] The structural formula of the glycine is as follows:

[0062]

[0063] Comparative Example 4

[0064] The difference between this comparative example and Example 3 is that p-aminobenzoic acid is used instead of guanidinoacetic acid in Example 3. The rest of the steps are exactly the same as those in Example 3.

[0065] The structural formula of the p-aminobenzoic acid is as follows:

[0066]

[0067] Comparative Example 5

[0068] The difference between this comparative example and Example 4 is that alanine is used instead of the guanidinopropionic acid in Example 4. The rest of the steps are the same as those in Example 4.

[0069] The structural formula of the alanine is as follows:

[0070]

[0071] The performance of CMP (Chemical Mechanical Polishing) polishing slurries is typically evaluated by measuring the polishing rate of silicon wafers. This rate is determined using a die geometry metrology system (WaferSight2+, KLATencor, Milpitas, CA, USA). The polishing rate is calculated by measuring the difference in mass before and after polishing the silicon wafer and dividing it by the polishing time.

[0072] Polishing rate testing was performed on the chemical mechanical polishing solutions obtained in Examples 1-4 and Comparative Examples 1-5. Specifically, the mass of the silicon wafers was measured before and after polishing, and the polishing rate was calculated by dividing the mass difference before and after polishing by the polishing time.

[0073] 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.

[0074] Table 1

[0075]

[0076]

[0077] As can be seen from Table 1, the chemical mechanical polishing solution obtained can achieve a polishing rate value higher than that of the comparative polishing solution, which shows that the chemical mechanical polishing solution provided in the present application can significantly improve the polishing rate of silicon wafers for IGBT.

Claims

1. A chemical mechanical polishing solution for polishing doped silicon wafers for IGBT, characterized by: Includes guanidine compounds, abrasives, alkaline compounds, water and other additives.

2. The chemical mechanical polishing solution according to claim 1, wherein: The guanidine compound includes one or more of arginine, guanidine acetic acid, 4-guanidine benzoic acid, guanidine propionic acid, and guanidine valeric acid; and the mass percentage concentration of the guanidine compound is 0.005-0.5%.

3. The chemical mechanical polishing solution according to claim 1, wherein: The abrasive comprises one or more of inorganic particles, organic particles, and organic-inorganic composite particles; and the mass percentage concentration of the abrasive is 1 to 40%.

4. The chemical mechanical polishing solution according to claim 1, wherein: The alkaline compound includes one or more of alkali metal hydroxides, carbonates, bicarbonates, and nitrogen-containing organic or inorganic alkaline compounds; the mass percentage concentration of the alkaline compound is 0.01-10%.

5. The chemical mechanical polishing solution according to claim 1, wherein: The water includes one or more of deionized water, pure water, ultrapure water, and distilled water; and the mass percentage concentration of the water is 50 to 99%.

6. The chemical mechanical polishing solution according to claim 1, wherein: The other additives include one or more of a chelating agent, a surfactant, a preservative, and a mildew inhibitor.

7. The chemical mechanical polishing solution according to claim 6, wherein: The chelating agent comprises one or more of carboxylic acids, organic phosphonic acids and organic sulfonic acids; the mass percentage concentration of the chelating agent is 0.0005% to 0.1%.

8. The chemical mechanical polishing solution according to claim 6, wherein: The surfactant includes one or more of a nonionic surfactant, a cationic surfactant and an anionic surfactant; the mass percentage concentration of the surfactant is 0.0001% to 0.1%.

9. The chemical mechanical polishing solution according to claim 6, wherein: The preservatives and mildew inhibitors are used alone or in combination.

10. The chemical mechanical polishing liquid according to claim 6, wherein: The preservative or mildew preventer comprises one or more of isothiazolinone series, paraoxybenzoic acid esters and parahydroxybenzoic acid esters; the mass percentage concentration of the preservative or mildew preventer is 0.001% to 0.1%.

Images