A shear-resistant, long-life grinding fluid and its preparation method and use

Abstract

The present invention provides a shear-resistant, long-life grinding fluid and a preparation method and use thereof. The shear-resistant, long-life grinding fluid comprises the following components in weight proportion: 5-15 parts of pH regulator; 3-10 parts of dispersant; 1-5 parts of wetting agent; 1-15 parts of thixotropic agent; 35-70 parts of deionized water. The present invention also discloses a preparation method of the shear-resistant, long-life grinding fluid and its use in the field of large-size single crystal silicon wafer grinding. The shear-resistant, long-life grinding fluid of the present invention is used to grind single crystal silicon, which has the following advantages: while enhancing the shear resistance, it also improves the problems of low removal rate and high TTV of traditional grinding fluid; reduces the content of iron ions in the mortar after grinding, and further improves the grinding sand recovery efficiency; can be recycled and has a long life; is also applicable to hard and brittle materials such as single crystal silicon, gallium nitride and silicon carbide.

Description

Technical Field

[0001] The invention relates to a grinding liquid technology, and in particular to a shear-resistant, long-life grinding liquid and a preparation method and application thereof. Background Art

[0002] With the development of semiconductor material technology, higher requirements are placed on the specifications and quality of silicon wafers. In the manufacturing process of large-size single-crystal silicon wafers for semiconductors, the grinding technical indicators of silicon wafers are more stringent, requiring silicon wafers to have smaller thickness differences and higher grinding rates. The grinding process is a key step in maintaining the quality of silicon wafers, and the grinding fluid used in this step is one of the core technologies that affect the grinding indicators. In recent years, new technical challenges have also been raised for the suspension, cyclic shear resistance and dispersion performance of the grinding fluid.

[0003] Some silicon wafer grinding fluids are disclosed in the prior art, for example: CN114231251A discloses a diamond grinding fluid for rough grinding of silicon carbide wafers and its preparation method, which belongs to the field of ultra-precision grinding processing technology. The grinding fluid is made of water and the following raw materials in parts by weight: 0.5-2 parts of diamond micropowder, 0.1-0.5 parts of surfactant, 0.2-0.8 parts of thickener, 0.5-7 parts of lubricant, 0.05-1 parts of dispersant, 1.5-5 parts of active agent for rust prevention and pH adjustment, and 0.01-0.2 parts of bactericide. The grinding fluid fully considers the cleaning performance and rust prevention performance of the grinding fluid.

[0004] CN106244022A discloses a grinding liquid for gallium nitride semiconductor wafers and a preparation method thereof. The grinding liquid comprises, by weight, 2-3 parts of abrasive, 0.5-1.5 parts of sodium phosphomolybdate, 0.5-1 parts of a thickener, 0.5-2 parts of a dispersant, 0.5-1.5 parts of a pH regulator, 1-2 parts of a chelating agent, 5-10 parts of a surfactant, and 10-20 parts of deionized water; wherein the abrasive has an average particle size of 0.6-0.8 μm and is composed of zirconium oxide, aluminum oxide, and cerium oxide, and the weight ratio of the three is 1:2-3:1.5-2.

[0005] CN115039203A discloses a polishing liquid, which contains abrasive grains, at least one hydroxy acid component selected from the group consisting of hydroxy acids and their salts, and compound Z, wherein compound Z has a hydrocarbon group and a polyoxyalkylene group that can be substituted. The polishing liquid group can be stored in a first liquid and a second liquid, wherein the first liquid contains abrasive grains and the second liquid contains a hydroxy acid component and compound Z. The flatness of the substrate after polishing is improved.

[0006] As mentioned above, the prior art has disclosed a variety of grinding liquids, but these grinding liquids have problems of shear resistance, poor grinding performance and short cycle life to varying degrees, and are difficult to meet the increasing grinding needs. Therefore, it is necessary to develop a grinding liquid with shear resistance and long cycle life. Summary of the invention

[0007] The purpose of the present invention is to propose a shear-resistant and long-life grinding fluid to address the problems of existing single crystal silicon grinding fluids such as lack of shear resistance, poor grinding performance and short cycle life. The grinding fluid has the following advantages: using the shear-resistant and long-life grinding fluid of the present invention to grind single crystal silicon has the following advantages: while enhancing the shear resistance, it also improves the problems of low removal rate and high TTV of traditional grinding fluids; reduces the content of iron ions in the mortar after grinding, and further improves the grinding sand recovery efficiency; can be recycled and has a long life; is also applicable to hard and brittle materials such as single crystal silicon, gallium nitride and silicon carbide.

[0008] It should be noted that, in the present invention, unless otherwise specified, the specific meaning of "including" in relation to composition limitations and descriptions includes both open-ended "including", "comprising", etc. and similar meanings, as well as closed-ended "composed of", "composed of", etc. and similar meanings.

[0009] To achieve the above object, the technical solution adopted by the present invention is: a shear-resistant, long-life grinding fluid, comprising the following components in weight proportions:

[0010]

[0011] Furthermore, the pH adjuster is an organic base.

[0012] Furthermore, the pH regulator is one or more of monoethanolamine, tromethamine, diethanolamine, ethylenediamine, meglumine and triethanolamine.

[0013] Furthermore, the pH regulator is preferably tromethamine.

[0014] Furthermore, the pH adjuster is 5-10 parts.

[0015] Furthermore, the pH value of the shear-resistant and long-life grinding liquid is 7-9.

[0016] Furthermore, the pH of the shear-resistant, long-life grinding fluid is preferably 8-9.

[0017] Furthermore, the dispersant is one or more of UiO-66-NH2, MOF-5, MOF-177 and MIL-101.

[0018] Furthermore, the dispersant is preferably UiO-66-NH2.

[0019] Furthermore, the dispersant is 5-8 parts.

[0020] Furthermore, the wetting agent is one or more of α-sulfo fatty acid methyl ester sodium salt, coconut glucoside, lauryl glucoside, N-acetylglucosamine, AEC-9Na, potassium monododecyl phosphate and sodium fatty alcohol polyoxyethylene ether sulfate.

[0021] Furthermore, the wetting agent is preferably sodium fatty alcohol polyoxyethylene ether sulfate.

[0022] Furthermore, the wetting agent is 1-3 parts.

[0023] Furthermore, the thixotropic agent is polyvinyl alcohol and / or polyacrylic acid.

[0024] Furthermore, the thixotropic agent is preferably polyvinyl alcohol with a molecular weight of 150,000-250,000 and / or polyacrylic acid with a molecular weight of 3,000-5,000.

[0025] Furthermore, the thixotropic agent is more preferably polyvinyl alcohol with a molecular weight of 180,000-200,000.

[0026] Furthermore, the thixotropic agent is 5-10 parts.

[0027] Furthermore, the deionized water is 40-60 parts.

[0028] Another object of the present invention is to disclose a method for preparing the shear-resistant and long-life grinding liquid, comprising the following steps:

[0029] Step 1: Weigh each component according to the weight ratio;

[0030] Step 2: first add deionized water into the reaction container, then add the dispersant, and stir evenly;

[0031] Step 3: Add the wetting agent, thixotropic agent and pH adjuster into the reaction container and stir to obtain a shear-resistant and long-life grinding liquid.

[0032] Furthermore, in step 2, the stirring speed is 30-100 r / min, and the stirring time is 10-60 min.

[0033] Furthermore, in step 3, the stirring speed is 45-80 r / min, and the stirring time is 60-90 min.

[0034] Another object of the present invention is to disclose the use of the shear-resistant and long-life grinding fluid in the field of grinding large-size single-crystal silicon wafers.

[0035] Furthermore, the hard and brittle material is single crystal silicon, gallium nitride or silicon carbide.

[0036] Furthermore, the method for grinding large-size single crystal silicon wafers using the shear-resistant and long-life grinding liquid is as follows:

[0037] Step 1: dilute the shear-resistant, long-life grinding fluid by 30-60 times;

[0038] Step 2: Add the abrasive sand to the diluent and stir evenly;

[0039] Step 3: Grind the large-size single crystal silicon wafer using a grinder.

[0040] Furthermore, the abrasive sand is aluminum oxide abrasive sand.

[0041] Furthermore, the alumina grinding sand has a particle size of 8-15 microns.

[0042] Furthermore, the mass ratio of the diluent to the abrasive sand is 0.6-1.2:5-20.

[0043] Furthermore, the stirring time in step 2 is 10-20 min.

[0044] Furthermore, the grinding conditions in step 3 are: mill speed 30-100r / min, pressure 20-100kg, flow rate 5-200mL / min, and grinding time 5-15min.

[0045] The shear-resistant, long-life grinding fluid and its preparation method and use of the present invention have the following advantages compared with the prior art:

[0046] 1) The dispersant selected for the grinding liquid of the present invention can reduce the content of iron ions in the mortar liquid after grinding and improve the recovery efficiency of grinding sand; at the same time, the addition of the dispersant makes the grinding liquid resistant to shearing and has more stable grinding performance. For example, UiO-66-NH2 forms a stable chelate with heavy metal ions through its rich amino and hydroxyl groups, thereby chelating iron ions, reducing the content of iron ions in the grinding liquid after grinding, and improving the quality of silicon wafers after grinding; and UiO-66-NH2 has a porous octahedral structure, high thermal stability, and can maintain the stability of the crystal structure in a variety of solvents, so that UiO-66-NH2 can resist physical shear force in the grinding liquid, that is, the shearing and breaking effect of the abrasive on it, and is not easily destroyed, which can improve the overall shear resistance of the grinding liquid and promote it to still exert its better grinding performance during the recycling process.

[0047] 2) The grinding liquid of the present invention adopts a high molecular weight thixotropic agent, such as polyvinyl alcohol (molecular weight 150,000-250,000). The larger the molecular weight, the longer the polyvinyl alcohol chain, the higher the degree of cross-linking, and the probability of breaking under shear force is correspondingly reduced. At the same time, its molecules have the ability to crystallize and form a hard structure, making the polyvinyl alcohol solution with high crystallinity more difficult to shear and break, thereby improving the overall shear resistance of the grinding liquid and further extending the service life of the grinding liquid.

[0048] In summary, the shear-resistant and long-life polishing liquid of the present invention has excellent performance, is resistant to shearing and has a long life, and has good application prospects and large-scale production potential in the field of large-size single crystal silicon wafer polishing. DETAILED DESCRIPTION

[0049] The present invention is further described below with reference to the examples. The description of the technical features described below is based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0050] Unless otherwise stated, the units used in this specification are all international standard units, and the numerical values ​​and numerical ranges appearing in the present invention should be understood to include the inevitable systematic errors in industrial production.

[0051] In this specification, the numerical range expressed using "a numerical value A to a numerical value B" means a range including the endpoints numerical values ​​A and B.

[0052] In the present specification, a numerical range expressed using "above" or "below" means a numerical range including the number.

[0053] In this specification, the word "may" means both performing a certain process and not performing a certain process.

[0054] In this specification, the use of "optional" or "optional" indicates that certain substances, components, execution steps, application conditions and other factors are used or not used.

[0055] In this specification, when "normal temperature" or "room temperature" is used, the temperature may be 15-25°C.

[0056] In this manual, the reagents or instruments used without indicating the manufacturer are all conventional products that can be obtained through commercial purchase.

[0057] Examples 1-6

[0058] Examples 1-6 disclose a variety of shear-resistant, long-life polishing fluids, the components and weight ratios of which are shown in Table 1, and the preparation methods thereof are as follows:

[0059] Step 1: Weigh each component according to the weight ratio;

[0060] Step 2: first add deionized water into the reaction vessel, then add the dispersant, stir while adding, and stir at 60r / min for 35min;

[0061] Step 3: Add the wetting agent, thixotropic agent and pH adjuster into the reaction vessel and stir at 50 r / min for 65 min.

[0062] Table 1 Components and mass ratios of shear-resistant, long-life polishing fluids of Examples 1-6

[0063]

[0064]

[0065] Comparative Examples 1-3

[0066] Comparative Examples 1-3 disclose a variety of grinding liquids, the components and mass ratios of which are shown in Table 2, and the preparation methods thereof are the same as those of Example 1.

[0067] Table 2 Components and mass ratios of the grinding fluids of Comparative Examples 1-3

[0068]

[0069] The removal rate and TTV tests were performed on the polishing liquids of Examples 1-6 and Comparative Examples 1-3, respectively. The test results are shown in Table 3.

[0070] Table 3 Test results

[0071]

[0072] As shown in Table 3, in Examples 1-6 of the present invention, the material removal rate (MRR) was 8.5-9.2 μm / min for the first time and 8.3-8.8 μm / min for the second time. The TTV after the first grinding was 1.01-1.10 μm and 1.02-1.14 μm for the second time.

[0073] Comparative Examples 1-3: The material removal rate (MRR) of the first grinding was 8.4-8.8 μm / min, and that of the second grinding was 8.1-8.7 μm / min; the TTV after the first grinding was 1.12-1.29 μm, and that of the second grinding was 1.20-1.40 μm.

[0074] Compared with the control example, the material removal rate of the embodiment of the present invention is faster in grinding once or twice, and the TTV value is also lower overall. The smaller the TTV, the better the flatness of the silicon wafer after grinding, which further proves that the grinding fluid of the embodiment of the present invention has the effect of resisting long-term shearing.

[0075] In Comparative Example 1, no dispersant was added, resulting in insufficient dispersion of the abrasive in the solution, and thus poor grinding effect on the substrate, low material removal rate, and relatively high TTV.

[0076] In Comparative Example 2, the structure of CD-MOFs collapses when it comes into contact with water, while that of UiO66-NH2 does not. Therefore, the specific surface area of ​​CD-MOFs is smaller than that of UiO66-NH2, and its ability to chelate metal ions is poorer. In addition, polyvinyl alcohol (molecular weight 10,000) has a smaller molecular weight than that of Example 1, so its shear resistance and suspension properties are relatively poor, and therefore its grinding rate is lower.

[0077] In Comparative Example 3, the dispersant used is sodium tripolyphosphate, which has a small molecular weight, and its dispersibility and suspension properties are relatively poor. At the same time, its shear resistance is also relatively weak, so its grinding rate is low.

[0078] In addition, the iron ion content in the mortar liquid after grinding of Examples 1-6 was detected to be less than 0.001ppm, and the iron ion content in the mortar liquid after grinding of Comparative Examples 1-3 was 0.01ppm to 0.1ppm. In semiconductor manufacturing, strict control of the concentration of iron ions can avoid the negative impact of iron ions on the performance of devices.

[0079] Test Method

[0080] The grinding liquids of Example 1-6 and Comparative Example 1-3 were used to grind a 12-inch single crystal silicon wafer in the following manner:

[0081] Step 1: Dilute the grinding solution 40 times;

[0082] Step 2: Add alumina grinding sand (particle size 10 μm) to the above dilution, the mass ratio of the diluted grinding liquid to the alumina grinding sand is 0.6:10, and stir for 13 minutes;

[0083] Step 3: Set the grinding machine speed to 40r / min, the pressure to 85kg, the flow rate to 150mL / min, and the grinding time to 10min.

[0084] Testing methods for removal rate and TTV:

[0085] The test method for the first grinding removal rate and the removal rate after the second cycle grinding is:

[0086] MRR is the removal rate (μm / min), the mass of the silicon wafer before grinding is m1 (g), the mass after grinding is m2 (g), the grinding time is t (min), and ρ is the density of the silicon wafer (g / cm 3 ), s is the silicon wafer area (cm 2 );

[0087] Formula: MRR = (m1-m2)*10 4 / ρst.

[0088] The test method for TTV after the first grinding and TTV after the second grinding is:

[0089] After grinding, measure with a thickness gauge, TTV = maximum thickness - minimum thickness.

[0090] Test method for iron ion content:

[0091] The ground slurry was allowed to stand, settle, and filter, and then the liquid was taken for ICP testing to test the iron ion content.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein by equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A shear-resistant, long-life polishing fluid, characterized in that: The composition includes the following components in weight ratio:

2. The shear-resistant, long-life polishing fluid according to claim 1, characterized in that: The pH adjuster is an organic base.

3. The shear-resistant, long-life polishing fluid according to claim 1 or 2, characterized in that: The pH of the grinding liquid is 7-9.

4. The shear-resistant, long-life polishing fluid according to claim 1, characterized in that: The dispersant is one or more of UiO-66-NH2, MOF-5, MOF-177 and MIL-101.

5. The shear-resistant, long-life polishing fluid according to claim 1, characterized in that: The wetting agent is one or more of α-sulfo fatty acid methyl ester sodium salt, coconut glucoside, lauryl glucoside, N-acetylglucosamine, AEC-9Na, potassium monododecyl phosphate and sodium fatty alcohol polyoxyethylene ether sulfate.

6. The shear-resistant, long-life polishing fluid according to claim 1, characterized in that: The thixotropic agent is polyvinyl alcohol and / or polyacrylic acid.

7. A method for preparing the shear-resistant and long-life polishing liquid according to any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Weigh each component according to the weight ratio; Step 2: first add deionized water into the reaction vessel, then add the dispersant, and stir evenly; Step 3: Add the wetting agent, thixotropic agent and pH adjuster into the reaction container and stir to obtain a shear-resistant and long-life grinding liquid.

8. The method for preparing a shear-resistant, long-life polishing liquid according to claim 7, characterized in that: The stirring speed in step 2 is 30-100 r / min, and the stirring time is 10-60 min; And / or, the stirring speed in step 3 is 45-80 r / min, and the stirring time is 60-90 min.

9. Use of the shear-resistant, long-life polishing fluid according to any one of claims 1 to 6 in the field of polishing large-size single-crystal silicon wafers.

10. The use according to claim 9, characterized in that: The method for grinding large-size single crystal silicon wafers using the shear-resistant and long-life grinding liquid is as follows: Step 1: dilute the shear-resistant, long-life grinding fluid by 30-60 times; Step 2: Add the abrasive sand to the diluent and stir evenly; Step 3: Grind the large-size single crystal silicon wafer using a grinder.

Images