Chemical mechanical polishing solution for effectively improving polishing rate of silicon wafer for IGBT (Insulated Gate Bipolar Translator)

Abstract

The invention relates to a chemical mechanical polishing solution for effectively improving the polishing rate of a silicon wafer for an IGBT (Insulated Gate Bipolar Translator). The chemical mechanical polishing solution comprises water-soluble micromolecules containing a multi-nitrogen heterocyclic ring structure, a grinding material, an alkaline compound and water. According to the chemical mechanical polishing solution provided by the invention, the polishing rate of the silicon wafer for the IGBT can be remarkably improved, the chemical reactivity of the surface of the silicon wafer is effectively improved, and the material removal efficiency in the polishing process is enhanced, so that the polishing rate of the silicon wafer for the IGBT is remarkably improved. Meanwhile, the additive has good water solubility and dispersion stability, surface defects such as scratches and corrosion are not prone to being caused, the surface quality of wafers is guaranteed, and the additive is suitable for the preparation technology of devices with the requirements for high flatness and high cleanliness. In addition, the polishing solution system is environmentally friendly, has good process compatibility, is suitable for existing CMP equipment, and has high industrial application potential.

Description

Technical Field

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

[0002] With the development of the integrated circuit industry, advanced manufacturing processes have placed higher demands on the polishing efficiency of silicon wafers used in insulated gate bipolar transistors (IGBTs). Technologies such as chemical mechanical polishing (CMP) and double-side chemical mechanical polishing (DSP) can achieve high-level planarization of silicon wafers.

[0003] CMP technology combines chemical and mechanical processes, offering advantages such as high processing speed, high polishing quality, and reliable results. However, numerous factors influence the polishing rate of IGBT silicon wafers during processing, including the workpiece surface material, the composition of the polishing slurry, and the pressure of the polishing head. This makes it difficult to directly and effectively increase the polishing rate of IGBT silicon wafers. Therefore, a technical solution is needed to effectively increase the chemical mechanical polishing rate of silicon wafers. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a chemical mechanical polishing liquid that effectively improves the polishing rate of silicon wafers for IGBTs. The chemical mechanical polishing liquid can significantly improve the polishing rate of silicon wafers for IGBTs and has good application prospects.

[0005] The invention provides a chemical mechanical polishing liquid for effectively improving the polishing rate of silicon wafers for IGBT, comprising water-soluble small molecules containing a polynitrogen heterocyclic structure, abrasives, alkaline compounds and water.

[0006] Preferably, the water-soluble small molecules containing a polynitrogen heterocyclic structure include one or more of 1,4,8,11-tetraazacyclotetradecane, 1,4,7-triazacyclononane, 1,4,8,12-tetraazacyclopentadecane, 1,4,7,10,13-pentaazacyclopentadecane, and 1,5,9-triazacyclododecane; and the mass percentage concentration of the water-soluble small molecules containing a polynitrogen heterocyclic structure is 0.005 to 0.5%.

[0007] 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%.

[0008] 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.

[0009] 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.

[0010] 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.

[0011] 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.

[0012] 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.

[0013] 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.

[0014] Preferably, the alkaline compound is one or more of ammonia water, potassium hydroxide, sodium hydroxide, tetramethylammonium hydroxide, and potassium carbonate.

[0015] 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.

[0016] Furthermore, the chemical mechanical polishing solution also includes other additives.

[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 solution provided by the present invention can significantly increase the polishing rate of silicon wafers for IGBTs, effectively enhancing the chemical reactivity of the silicon wafer surface and increasing the material removal efficiency during the polishing process, thereby significantly improving the polishing rate of silicon wafers for IGBTs. Furthermore, this type of additive has good water solubility and dispersion stability, is less likely to cause surface defects such as scratches and corrosion, and ensures the surface quality of the wafer, making it suitable for device preparation processes requiring high flatness and high cleanliness. Furthermore, this polishing solution system is environmentally friendly, has good process compatibility, is suitable for existing CMP equipment, and has strong potential for industrial application. 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 chemical mechanical polishing solution is provided for effectively improving the polishing rate of silicon wafers for IGBTs, 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 1,4,8,11-tetraazacyclotetradecane, 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 1,4,8,11-tetraazacyclotetradecane is as follows:

[0040]

[0041] Example 2

[0042] In this embodiment, 1,4,7-triazacyclononane is used to replace 1,4,8,11-tetraazacyclotetradecane in Example 1, and the rest of the ingredients remain the same as those in Example 1.

[0043] The structural formula of the 1,4,7-triazacyclononane is as follows:

[0044]

[0045] Example 3

[0046] In this embodiment, 1,4,8,12-tetraazacyclopentadecane is used to replace 1,4,8,11-tetraazacyclotetradecane in Example 1, and the rest of the components remain the same as those in Example 1.

[0047] The structural formula of the 1,4,8,12-tetraazacyclopentadecane is as follows:

[0048]

[0049] Example 4

[0050] In this embodiment, 1,4,7,10,13-pentaazacyclopentadecane is used to replace 1,4,8,11-tetraazacyclotetradecane in Example 1, and the rest of the components remain the same as those in Example 1.

[0051] The structural formula of the 1,4,7,10,13-pentaazacyclopentadecane is as follows:

[0052]

[0053] Example 5

[0054] In this embodiment, 1,5,9-triazacyclododecane is used to replace 1,4,8,11-tetraazacyclotetradecane in Example 1, and the rest of the ingredients remain the same as those in Example 1.

[0055] The structural formula of the 1,5,9-triazacyclododecane is as follows:

[0056]

[0057] Comparative Example 1

[0058] This comparative example differs from Example 1 in that no water-soluble small molecule with a polynitrogen heterocyclic structure, namely, 1,4,8,11-tetraazacyclotetradecane, is used. The rest of the reaction is identical to Example 1.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 1 is that ethanolamine is used instead of 1,4,8,11-tetraazacyclotetradecane in Example 1. The rest of the steps are the same as those in Example 1.

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

[0062]

[0063] Comparative Example 3

[0064] The difference between this comparative example and Example 1 is that diethanolamine is used instead of 1,4,8,11-tetraazacyclotetradecane in Example 1. The rest of the steps are the same as those in Example 1.

[0065] The structural formula of the diethanolamine is as follows:

[0066]

[0067] 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.

[0068] Polishing rate testing was performed on the chemical mechanical polishing solutions obtained in Examples 1-5 and Comparative Examples 1-3. 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.

[0069] 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.

[0070] Table 1

[0071] Additive molecules Polishing rate Example 1 1,4,8,11-Tetraazacyclotetradecane 159％ Example 2 1,4,7-Triazacyclononane 164％ Example 3 1,4,8,12-Tetraazacyclopentadecane 162％ Example 4 1,4,7,10,13-Pentaazacyclopentadecane 135％ Example 5 1,5,9-Triazacyclododecane 171％ Comparative Example 1 none 100％ Comparative Example 2 Ethanolamine 107％ Comparative Example 3 Diethanolamine 110％

[0072] 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 that effectively improves the polishing rate of silicon wafers for IGBTs, characterized by: The invention comprises water-soluble small molecules containing a polynitrogen heterocyclic structure, abrasives, alkaline compounds and water.

2. The chemical mechanical polishing solution according to claim 1, wherein: The water-soluble small molecules containing a polynitrogen heterocyclic structure include one or more of 1,4,8,11-tetraazacyclotetradecane, 1,4,7-triazacyclononane, 1,4,8,12-tetraazacyclopentadecane, 1,4,7,10,13-pentaazacyclopentadecane, and 1,5,9-triazacyclododecane; the mass percentage concentration of the water-soluble small molecules containing a polynitrogen heterocyclic structure is 0.005 to 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 chemical mechanical polishing solution also includes other additives.

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

8. The chemical mechanical polishing solution according to claim 7, 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%.

9. The chemical mechanical polishing solution according to claim 7, 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%.

10. The chemical mechanical polishing liquid according to claim 7, 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%.

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