A large-size silicon wafer polishing liquid with high removal rate and low scratch, and its preparation method and use

Abstract

The present invention relates to a large-size silicon wafer polishing liquid with high removal rate and low scratch, which comprises the following components calculated by weight: 4-20 parts of catalyst auxiliary agent; 4-15 parts of catalyst; 4-20 parts of oxidant; 8-20 parts of dispersant; 8-20 parts of pH regulator; 20-40 parts of deionized water. The present invention also discloses a preparation method of the above-mentioned polishing liquid. In the present invention, the catalyst auxiliary agent contains a specific group, which can effectively assist the catalyst in oxidizing the silicon wafer, and the catalyst auxiliary agent containing a pyridine group attracts photogenerated electrons, reduces the activation energy of the reaction, accelerates the oxidation process, and accelerates the removal rate. The catalyst auxiliary agent can also play a wetting role at the same time and cooperate with the dispersant to increase the dispersion effect. The oxidant and the catalyst synergistically improve the oxidation ability, increase the oxidation rate of the silicon wafer, and then increase the polishing rate.

Description

Technical Field

[0001] The invention belongs to the field of semiconductor manufacturing technology, and in particular relates to a large-size silicon wafer polishing liquid with high removal rate and low scratch, 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. The market demand for large-diameter silicon wafers suitable for micro-processing will increase day by day.

[0003] In the manufacturing process of large-size single-crystal silicon wafers for semiconductors, the grinding technical indicators of silicon wafers are more stringent, requiring the silicon wafers to have a higher removal rate, smaller thickness difference and lower damage layer depth, etc. 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. It is crucial to use the grinding fluid to increase the removal rate of silicon wafers and reduce scratches during the grinding process. Summary of the invention

[0004] The technical problem solved by the present invention is to increase the removal rate of silicon wafers by means of grinding liquid and reduce scratches during the grinding process.

[0005] In view of the technical problems existing in the prior art, the present invention designs a large-size silicon wafer polishing liquid with high removal rate and low scratches, and a preparation method and use thereof.

[0006] In order to solve the above-mentioned technical problems, the present invention adopts the following solutions:

[0007] A large-size silicon wafer polishing liquid with high removal rate and low scratch, characterized in that it comprises the following components calculated by weight:

[0008]

[0009]

[0010] Wherein, the catalyst auxiliary agent is one or more of 5,6-dimethyl-3-carboxyl-2-pyridone, N-butyl pyridinium sulfonate dihydrogen phosphate, and N-butyl sulfonate-3-methylpyridinium p-toluenesulfonate;

[0011] The catalyst is one or more of zinc oxide, titanium dioxide and indium oxide;

[0012] The oxidant is one of hydrogen peroxide, sodium periodate, potassium permanganate, potassium persulfate and potassium bromate.

[0013] Furthermore, the dispersant is one or more of phosphate monoester, polyphosphate ester, pyrophosphate ester, vinyl bisstearamide, stearic acid monoglyceride, and tristearic acid glyceride.

[0014] Furthermore, the pH regulator is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, and ammonia water.

[0015] Furthermore, the catalyst promoter is N-butyl pyridinium sulfonate dihydrogen phosphate;

[0016] The catalyst is titanium dioxide.

[0017] Further, the oxidant is potassium permanganate;

[0018] The dispersant is polyphosphate.

[0019] Further, the pH adjusting agent is sodium hydroxide;

[0020] The pH value of the solution after adjustment by the pH adjuster is 9-12.

[0021] The present invention also discloses a method for preparing a large-size silicon wafer polishing liquid with high removal rate and low scratch, which is characterized by comprising the following steps:

[0022] Step 1: Stir deionized water and pH regulator evenly at room temperature at 100-300 rpm for 5-10 minutes to obtain a pH regulator solution;

[0023] Step 2: adding the catalyst to the pH adjusting agent solution obtained in step 1, wherein the conditions are a rotation speed of 300-1000 rpm, a temperature of 30-60° C., and a time of 5-15 min to obtain solution A;

[0024] Step 3: adding a catalyst promoter to the above solution A, wherein the conditions are a rotation speed of 300-1000 rpm, a temperature of 30-60° C., and a time of 5-15 min to obtain a solution B;

[0025] Step 4: Add the oxidant and dispersant to the above solution B respectively, wherein the conditions are a rotation speed of 300-1000 rpm, a temperature of 30-60°C, and a time of 10-30 min to obtain a large-size silicon wafer polishing liquid with a high removal rate and low scratches.

[0026] The present invention also discloses a method for using a large-size silicon wafer polishing liquid with high removal rate and low scratch, which is characterized by comprising the following steps:

[0027] Step 1: dilute the prepared high removal rate, low scratch large-size silicon wafer polishing liquid by 15-35 times and set aside;

[0028] Step 2: setting ultraviolet light to irradiate the surface of the silicon wafer, the ultraviolet light wavelength is 200-400nm;

[0029] Step 3: adding the grinding abrasive at a mass fraction of 10-30% to the diluted grinding liquid obtained in step 1 and stirring for 8-15 minutes at a speed of 30-200 rpm to obtain a grinding liquid with the grinding abrasive added;

[0030] Step 4: Grinding an 8 / 12 inch silicon wafer with the grinding liquid containing grinding abrasive obtained in step 3, wherein the grinding conditions are a grinding machine speed of 50-100 r / min, a pressure of 60-100 kg, a flow rate of 5-200 mL / min, and a grinding time of 10-30 min;

[0031] Wherein, the grinding abrasive in step 3 is one or more of silicon dioxide, cerium oxide, diamond, boron nitride, zirconium oxide, and aluminum oxide; and the particle size range of the aluminum oxide grinding abrasive is 1-20 μm.

[0032] The grinding abrasive is preferably a mixed abrasive of aluminum oxide and cerium oxide, and the mass ratio of aluminum oxide to cerium oxide is 3:1-2:1.

[0033] The invention also discloses the use of a large-size silicon wafer grinding liquid with high removal rate and low scratch in silicon wafer grinding.

[0034] In some specific embodiments of the present invention, the catalyst additive may preferably be 5-10 parts; the catalyst 5-10 parts; the oxidant 5-10 parts; the dispersant 10-15 parts; the pH adjuster 10-15 parts; and the deionized water 25-35 parts.

[0035] In the present invention, the grinding abrasive is a mixed abrasive of aluminum oxide and cerium oxide, and the mass ratio of aluminum oxide to cerium oxide may be further preferably 2.3: 1. The particle size range of the aluminum oxide grinding abrasive may be further preferably 5-10 μm.

[0036] In the present invention, the mechanism for increasing the removal rate is:

[0037] First, titanium dioxide is an n-type semiconductor material. When it is exposed to ultraviolet light, the electrons in the valence band will gain the energy of photons and jump to the conduction band, thereby forming photogenerated electrons, and the remaining holes can oxidize the silicon wafer. The pyridine group in the catalyst additive contains lone pairs of electrons, so it has the ability to attract electrons. During the grinding process, the catalyst additive containing pyridine groups attracts the photogenerated electrons generated in the photocatalytic process, reducing the activation energy of the reaction, thereby accelerating the oxidation process of the silicon wafer and accelerating the removal rate.

[0038] Second, when titanium dioxide is exposed to ultraviolet light, it can produce highly active hole / electron pairs, and the holes can combine with water to generate ·OH to oxidize the silicon wafer. The oxidant acts as an electron acceptor and is reduced by accepting the photogenerated electrons on the surface of TiO2, reducing the chance of recombination between the photogenerated electrons and holes, thereby improving the oxidizing capacity of ·OH and the oxidant, increasing the oxidation rate of the silicon wafer, and thus increasing the grinding rate.

[0039] Third, the catalyst adjuvant can also cooperate with the dispersant selected in the present invention to further play a dispersing role and increase the removal rate of silicon dioxide.

[0040] Fourth, the catalyst promoter has a pyridine group at one end and a sulfonic acid group at the other end, which can simultaneously play a wetting role and cooperate with the dispersant to further increase the removal rate of silica.

[0041] Fifth, under alkaline conditions, silicon wafers can react to form silicates, reducing their hardness, thereby reducing the difficulty of grinding the silicon wafers. Under the premise of controlling the stability of the system, the reaction is more likely to occur under the pH conditions of the present invention. Therefore, it can be said that grinding under the pH conditions of the present invention helps to improve the removal efficiency.

[0042] In some practical applications, the high removal rate and low scratch polishing liquid of the present invention is also applicable to semiconductor materials such as gallium nitride and sapphire.

[0043] 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" and similar meanings, and closed-ended "consisting of..." and similar meanings.

[0044] The present invention provides a large-size silicon wafer polishing liquid with high removal rate and low scratch, a preparation method and use thereof, which have the following beneficial effects:

[0045] (1) The catalyst promoter used in the present invention contains both a pyridine group and a sulfonic acid group, which has the following advantages:

[0046] First, titanium dioxide is an n-type semiconductor material. When it is exposed to ultraviolet light, the electrons in the valence band will gain the energy of photons and jump to the conduction band, thereby forming photogenerated electrons, and the remaining holes can oxidize the silicon wafer. The pyridine group contains lone pairs of electrons, so it has the ability to attract electrons. During the grinding process, the catalyst additive containing the pyridine group attracts the photogenerated electrons generated in the photocatalytic process, reducing the activation energy of the reaction, thereby accelerating the oxidation process of the silicon wafer and accelerating the removal rate.

[0047] Secondly, the catalyst additive has a pyridine group at one end and a sulfonic acid group at the other end, which can simultaneously play a wetting role. Therefore, the present invention does not require the addition of additional surfactant components, thereby reducing the side reaction effects of multiple components on the grinding liquid and reducing costs.

[0048] Thirdly, the catalyst adjuvant can cooperate with the dispersant selected in the present invention to further play a dispersing role and increase the removal rate of silicon dioxide.

[0049] (2) The oxidant in the present invention has a special effect on the catalyst:

[0050] When titanium dioxide is exposed to ultraviolet light, it can produce highly active hole / electron pairs, and the holes can combine with water to generate OH to oxidize the silicon wafer. The oxidant acts as an electron acceptor and is reduced by accepting the photogenerated electrons on the TiO2 surface, reducing the chance of recombination of photogenerated electrons and holes.

[0051] This can improve the oxidizing ability of OH and the oxidant, increase the oxidation rate of the silicon wafer, and thus increase the polishing rate.

[0052] (3) The grinding liquid mentioned in the present invention is prepared under the condition of pH 9-12, which has special significance:

[0053] Under alkaline conditions, silicon wafers can react to form silicates, reducing their hardness and making them easier to grind. Under the premise of keeping the control system stable, the reaction is more likely to occur under this pH condition. Therefore, it can be said that grinding under this pH condition helps improve removal efficiency.

[0054] (4) The dispersant used in the present invention has multiple meanings:

[0055] First, the dispersant selected in the present invention is non-ionic, which can still play the role of a dispersant in a strongly alkaline solution, ensuring an excellent dispersing effect in the grinding liquid, which is unattainable by other anionic / cationic dispersants.

[0056] Secondly, the dispersant selected in the present invention can be used in conjunction with a catalyst adjuvant to further enhance the dispersing effect and promote efficient removal of the grinding products. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 : is a picture of a silicon wafer after being polished using the polishing liquid of Example 1 of the present invention;

[0058] Figure 2 : This is a picture of a silicon wafer after being polished using the polishing liquid of Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0059] The present invention will be further described below in conjunction with specific embodiments and accompanying drawings:

[0060] For examples and tests, please refer to the preferred numbers of parts and the numerical ranges of removal rates below.

[0061] Table 1 Example

[0062]

[0063] Table 2 Comparative Examples

[0064]

[0065] Method for preparing large-size silicon wafer polishing slurry with high removal rate and low scratch

[0066] The preparation method of embodiment 1-2 comprises the following steps:

[0067] Step 1: Stir deionized water and a pH regulator evenly at room temperature at 200 rpm for 8 minutes to obtain a pH regulator solution;

[0068] Step 2: adding the catalyst to the pH adjusting agent solution obtained in step 1, wherein the conditions are a rotation speed of 600 rpm, a temperature of 50° C., and a time of 10 min to obtain solution A;

[0069] Step 3: adding a catalyst promoter to the above solution A, wherein the conditions are a rotation speed of 600 rpm, a temperature of 50° C., and a time of 10 min to obtain a solution B;

[0070] Step 4: Add the oxidant and dispersant to the above solution B respectively, wherein the conditions are a rotation speed of 600 rpm, a temperature of 50°C, and a time of 20 min, to obtain a high removal rate and low scratch polishing liquid suitable for large-size silicon wafers.

[0071] The preparation method of embodiment 3-4 comprises the following steps:

[0072] Step 1: Stir deionized water and pH regulator evenly at room temperature at 100 rpm for 10 minutes to obtain a pH regulator solution;

[0073] Step 2: adding the catalyst to the pH adjuster solution obtained in step 1, wherein the conditions are a rotation speed of 300 rpm, a temperature of 60° C., and a time of 15 min to obtain solution A;

[0074] Step 3: Add the catalyst promoter to the above solution A, wherein the conditions are a rotation speed of 300 rpm, a temperature of 60° C., and a time of 5 min to obtain solution B;

[0075] Step 4: Add the oxidant and dispersant to the above solution B respectively, wherein the conditions are a rotation speed of 300 rpm, a temperature of 60°C, and a time of 30 min, to obtain a high removal rate and low scratch polishing liquid suitable for large-size silicon wafers.

[0076] The preparation method of Example 5 comprises the following steps:

[0077] Step 1: Stir deionized water and pH regulator evenly at room temperature at 300 rpm for 5 minutes to obtain a pH regulator solution;

[0078] Step 2: adding the catalyst to the pH adjusting agent solution obtained in step 1, wherein the conditions are a rotation speed of 1000 rpm, a temperature of 30° C., and a time of 5 min to obtain solution A;

[0079] Step 3: adding a catalyst promoter to the above solution A, wherein the conditions are a rotation speed of 1000 rpm, a temperature of 30° C., and a time of 15 min to obtain a solution B;

[0080] Step 4: Add the oxidant and dispersant to the above solution B respectively, wherein the conditions are a rotation speed of 1000 rpm, a temperature of 30°C, and a time of 10 min, to obtain a high removal rate and low scratch polishing liquid suitable for large-size silicon wafers.

[0081] The preparation method of the grinding liquid of the comparative example in the present invention refers to the method in Example 1.

[0082] Method for using high removal rate and low scratch large size silicon wafer polishing liquid

[0083] The following steps are involved:

[0084] Step 1: dilute the prepared high removal rate and low scratch polishing liquid suitable for large-size silicon wafers by 25 times and set aside;

[0085] Step 2: setting ultraviolet light to irradiate the surface of the silicon wafer, the wavelength of the ultraviolet light is 300nm;

[0086] Step 3: Add the grinding abrasive at a mass fraction of 20% into the diluted grinding liquid obtained in step 1 and stir for 10 minutes at a speed of 100 rpm to obtain a grinding liquid with the grinding abrasive added;

[0087] Step 4: Grinding an 8 / 12 inch silicon wafer with the grinding liquid added with grinding abrasive obtained in step 3, wherein the grinding conditions are a grinding machine speed of 80 r / min, a pressure of 80 kg, a flow rate of 100 mL / min, and a grinding time of 15 min;

[0088] The grinding abrasive is a mixed abrasive of aluminum oxide and cerium oxide, and the mass ratio of aluminum oxide to cerium oxide is 2.3: 1. The particle size of the aluminum oxide grinding abrasive is 10 μm.

[0089] It should be noted that, by diluting the grinding liquid of the present invention by any multiple of 15-35 times, adding the grinding abrasive by any number of 10-30 parts by mass, and setting the grinding conditions within the scope of the present invention, a better grinding effect can be obtained.

[0090] About performance testing and description:

[0091] Performance 1 The test method for the grinding removal rate is:

[0092] Grind the silicon wafer according to the above-mentioned method of using the grinding liquid and record the following parameters:

[0093] The mass of silicon wafer before grinding is m1 (g),

[0094] Mass after grinding m2(g),

[0095] The grinding time is t (min),

[0096] ρ is the density of silicon wafer (g / cm 3 ),

[0097] s is the silicon wafer area (cm 2 ),

[0098] Removal rate (μm / min) MRR calculation formula: MRR = (m1-m2)*10 4 / ρst

[0099] Table 3 Test results

[0100] Serial number MRR Serial number MRR Example 1 6.8 Comparative Example 1 4.6 Example 2 5.8 Comparative Example 2 4.9 Example 3 5.6 Comparative Example 3 5.2 Example 4 6.4 Example 5 6.3

[0101] Analysis of the test results:

[0102] It can be seen from Table 3 that the removal rate MRR of the polishing liquid in the embodiment of the present invention is ≥5.6 μm / min, while the removal rate MRR of the polishing liquid in the comparative example is <5.5 μm / min.

[0103] It can be seen from Example 1 and Comparative Example 1 that although 4-hydroxypyridine also has negatively charged groups and pyridine groups, since the spatial volume of the hydroxyl group is not as large as that of the sulfonic acid group, in comparison, 4-hydroxypyridine cannot better cooperate with the dispersant to accelerate the removal rate.

[0104] It can also be seen from the comparison between Example 1 and Comparative Example 2 that, because the catalytic effect of zinc oxide is very weak and its stability is not as high as that of titanium dioxide, titanium dioxide can play a better role in the grinding process, which is not available in zinc oxide.

[0105] Finally, it can be seen from Example 1 and Comparative Example 3 that when a cationic dispersant is used, the removal rate becomes slower. The main reason is that the electronegative sulfonic acid group in the catalyst additive reacts with the cationic dispersant, reducing the activity of the catalyst additive, which better illustrates the advantages of non-ionic dispersants.

[0106] It can be seen from the above data that the polishing liquid in the present invention has a higher removal rate and a better polishing effect.

[0107] Further comparison is made through the attached drawings in the specification:

[0108] Figure 1 This is a picture of a silicon wafer after being polished using the polishing liquid of Example 1 of the present invention; Figure 2 This is a picture of a silicon wafer after being polished using the polishing liquid of Comparative Example 1 of the present invention.

[0109] from Figure 1 It can be seen from the figure that the silicon wafer after being polished using the polishing liquid of Example 1 of the present invention has a smooth surface without scratches.

[0110] from Figure 2 It can be seen that the silicon wafer is polished using the polishing liquid of Comparative Example 1 of the present invention, and there are obvious scratches on its surface.

[0111] from Figure 1 and Figure 2 It can be clearly seen from the comparison that the high removal rate and low scratch polishing liquid of the present invention has a better polishing effect.

[0112] The catalyst auxiliary agent in the present invention contains a specific group, which can effectively assist the catalyst in oxidizing the silicon wafer. The catalyst auxiliary agent containing a pyridine group attracts the photogenerated electrons generated in the photocatalytic process, reduces the activation energy of the reaction, accelerates the oxidation process, and accelerates the removal rate. The catalyst auxiliary agent can also play a wetting role and cooperate with the dispersant to increase the dispersion effect. The oxidant and the catalyst synergistically improve the oxidation ability, increase the oxidation rate of the silicon wafer, and then increase the grinding rate.

[0113] The present invention is described exemplarily above in conjunction with the embodiments and drawings. It is obvious that the implementation of the present invention is not limited to the above-mentioned methods. As long as various improvements are made using the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A large-size silicon wafer polishing liquid with high removal rate and low scratch, characterized in that: Calculated by weight, it includes the following components: 4-20 parts of catalyst additive; 4-15 parts of catalyst; 4-20 parts of oxidant; 8-20 parts of dispersant; 8-20 parts of pH regulator; 20-40 parts of deionized water; Wherein, the catalyst auxiliary agent is one or more of 5,6-dimethyl-3-carboxyl-2-pyridone, N-butyl pyridinium sulfonate dihydrogen phosphate, and N-butyl sulfonate-3-methylpyridinium p-toluenesulfonate; The catalyst is titanium dioxide; The oxidant is one of hydrogen peroxide, sodium periodate, potassium permanganate, potassium persulfate, and potassium bromate; The dispersant is one or more of phosphate monoester, polyphosphate ester, pyrophosphate ester, vinyl bisstearamide, stearic acid monoglyceride, and tristearic acid glyceride.

2. The large-size silicon wafer polishing liquid with high removal rate and low scratch according to claim 1, characterized in that: The pH regulator is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide and ammonia water.

3. The large-size silicon wafer polishing liquid with high removal rate and low scratch according to claim 2, characterized in that: The catalyst adjuvant is N-butyl pyridinium sulfonate dihydrogen phosphate.

4. The large-size silicon wafer polishing liquid with high removal rate and low scratch according to claim 3, characterized in that: The oxidant is potassium permanganate; The dispersant is polyphosphate.

5. The large-size silicon wafer polishing liquid with high removal rate and low scratch according to claim 4, characterized in that: The pH regulator is sodium hydroxide; The pH value of the solution after adjustment by the pH adjuster is 9-12.

6. A method for preparing a large-size silicon wafer polishing liquid with high removal rate and low scratching according to any one of claims 1 to 5, characterized in that: The steps include: Step 1: Stir deionized water and pH regulator evenly at room temperature at 100-300 rpm for 5-10 minutes to obtain a pH regulator solution; Step 2: adding the catalyst to the pH adjusting agent solution obtained in step 1, wherein the conditions are a rotation speed of 300-1000 rpm, a temperature of 30-60° C., and a time of 5-15 min to obtain solution A; Step 3: adding a catalyst promoter to the above solution A, wherein the conditions are a rotation speed of 300-1000 rpm, a temperature of 30-60° C., and a time of 5-15 min to obtain a solution B; Step 4: Add the oxidant and dispersant to the above solution B respectively, wherein the conditions are rotation speed 300-1000rpm, temperature 30-60℃, time 10-30min, to obtain a high removal rate and low scratch polishing liquid suitable for large-size silicon wafers.

7. A method for using the high removal rate, low scratch large-size silicon wafer polishing liquid according to any one of claims 1 to 5, characterized in that The following steps are involved: Step 1: dilute the prepared high removal rate and low scratch polishing liquid suitable for large-size silicon wafers by 15-35 times and set aside; Step 2: setting ultraviolet light to irradiate the surface of the silicon wafer, the ultraviolet light wavelength is 200-400nm; Step 3: adding the grinding abrasive at a mass fraction of 10% to 30% to the diluted high removal rate, low scratch grinding liquid obtained in step 1 and stirring for 8 to 15 minutes at a speed of 30 to 200 rpm to obtain a grinding liquid with the grinding abrasive added; Step 4: Grinding an 8 / 12 inch silicon wafer with the grinding liquid containing grinding abrasive obtained in step 3, wherein the grinding conditions are a grinding machine speed of 50-100 r / min, a pressure of 60-100 kg, a flow rate of 5-200 mL / min, and a grinding time of 10-30 min; Wherein, the grinding abrasive in step 3 is one or more of silicon dioxide, cerium oxide, diamond, boron nitride, zirconium oxide, and aluminum oxide; and the particle size range of the aluminum oxide grinding abrasive is 1-20 μm.

8. The method for using the high removal rate and low scratch large-size silicon wafer polishing liquid according to claim 7, characterized in that: The grinding abrasive is a mixed abrasive of aluminum oxide and cerium oxide, and the mass ratio of aluminum oxide to cerium oxide is 3:1-2:

1.

9. Use of the large-size silicon wafer polishing liquid with high removal rate and low scratching as claimed in any one of claims 1 to 5 in silicon wafer polishing.

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