JP6744295B2 - Abrasive materials and slurries - Google Patents

Description

The disclosed embodiments relate to abrasives and abrasive slurries.

Conventionally, there is known a method of polishing a surface of a base material by applying a polishing slurry in which abrasive grains containing manganese oxide or the like are dispersed in water or an aqueous solution (for example, see Patent Documents 1 to 3).

JP 2012-696A JP, 2013-82048, A International Publication No. 2013/054883

However, the above-mentioned polishing slurry has room for further improvement in that good polishing performance can be achieved at a relatively high polishing speed.

One aspect of the embodiment has been made in view of the above, and an object thereof is to provide an abrasive and a polishing slurry having excellent polishing speed and polishing performance.

The abrasive according to one aspect of the embodiment includes a polymer additive having a weight average molecular weight of 1200 or more and 15000 or less, and abrasive grains for polishing a base material which is silicon carbide. The abrasive grains include manganese oxide. The polymeric additive is selected from the group comprising polycarboxylic acids and polycarboxylic acid salts, polyacrylic acid and polyacrylic acid salts, salts of naphthalenesulfonic acid formalin condensates, polyvinyl alcohol, polyethylene glycol and polyvinylpyrrolidone. 1 Alternatively, it contains two or more water-soluble organic polymers.

According to one aspect of the embodiment, it is possible to provide an abrasive and a polishing slurry having excellent polishing speed and polishing performance.

FIG. 1 is an explanatory diagram illustrating an outline of an abrasive and a polishing slurry according to an embodiment. FIG. 2 is an explanatory diagram illustrating an example of base material polishing to which the polishing slurry according to the embodiment is applied.

Hereinafter, embodiments of an abrasive and an abrasive slurry disclosed in the present application will be described in detail with reference to the accompanying drawings. The present invention is not limited to the embodiments described below.

FIG. 1 is an explanatory diagram illustrating an outline of an abrasive and a polishing slurry according to an embodiment, and FIG. 2 is an explanatory diagram illustrating an example of a base material polishing to which the polishing slurry according to the embodiment is applied.

As shown in FIG. 1, the abrasive 3 according to the embodiment includes abrasive grains 1 and a polymer additive 2. By mixing the abrasive 3 with water at a predetermined ratio, a polishing slurry 5 in which the abrasive grains 1 are dispersed in a solution 4 of the polymer additive 2 (hereinafter referred to as "polymer additive solution") is prepared. It The details of each component constituting the polishing material 3 and the polishing slurry 5 will be described later.

Next, polishing of the base material to which the polishing slurry 5 is applied will be described. As shown in FIG. 2, the polishing slurry 5 is supplied onto a polishing pad 6 attached to a polishing machine (not shown), and the base material 7 to be polished is placed on the surface to be polished so that the substrate 7 is in contact with the polishing slurry 5. Put it. Next, when the polishing pad 6 is rotated at a predetermined rotation speed while the polishing slurry 5 is being replenished while the base material 7 is pressed against the polishing pad 6 with a predetermined pressing force, the rotation speed of the polishing pad 6 and the polishing slurry are increased. The base material 7 is polished at a polishing speed according to the composition of 5.

The polishing slurry 5 according to the embodiment can be applied to polishing using silicon carbide as the base material 7, but is not limited thereto. For example, the base material 7 may be made of a high hardness material such as gallium nitride or diamond. Hereinafter, the abrasive 3 and the polishing slurry 5 according to the embodiment will be further described.

The abrasive grains 1 contained in the abrasive 3 and the polishing slurry 5 according to the embodiment include manganese oxide. Examples of the manganese oxide include manganese monoxide (MnO), manganese dioxide (MnO ₂ ), trimanganese tetraoxide (Mn ₃ O ₄ ), dimanganese trioxide (Mn ₂ O ₃ ), and the like. , But not limited to these. Further, such manganese oxides may be used in combination of two or more kinds. Of these manganese oxides, manganese dioxide is more preferable because it has a particularly strong oxidizing power. Needless to say, as described above, the abrasive grains 1 need only include manganese oxide, and need not include components other than manganese oxide.

In addition, a two-layer structure including a core material and a coating layer (shell) that covers a part or the whole of the outer peripheral surface of the core material is provided, and so-called core-shell particles containing manganese oxide in one of the two-layer structure are provided. It may be used as the abrasive grain 1.

The average particle size of the abrasive grains 1 is preferably 0.08 μm or more and 3.0 μm or less, more preferably 0.3 μm or more and 1.0 μm or less. If the average grain size of the abrasive grain 1 is less than 0.08 μm, a sufficient polishing rate may not be obtained. If the average grain size of the abrasive grains 1 exceeds 3.0 μm, sufficient polishing performance may not be obtained, that is, the surface roughness Ra of the polished base material 7 may increase. Here, the "average particle diameter of the abrasive grains 1" refers to the 50% diameter (d50) in the volume-based cumulative fraction of the laser diffraction/scattering particle diameter distribution measurement. Specifically, Microtrac 3300EXII manufactured by Nikkiso Co., Ltd. is applied as a measuring device, and the abrasive 3 or the abrasive slurry 5 is put into the chamber of the sample circulator until it is determined that the concentration is appropriate. Further, as the dispersion medium, a 0.1 wt% sodium hexametaphosphate aqueous solution was used, and ultrasonic waves having an output of 30 W were irradiated for 3 minutes in the sample circulator, and then the measurement was performed to find that the average particle size of the abrasive grains 1 was can get.

Next, the polymer additive 2 will be described. As the polymer additive 2, a water-soluble component capable of suppressing aggregation of the abrasive grains 1 in the aqueous solution is applied. Therefore, as described above, the polishing slurry 5 has a state in which the abrasive grains 1 are dispersed in the polymer additive solution 4. The polishing slurry 5 in which the polymer additive 2 is appropriately mixed suppresses the aggregation of the abrasive grains 1 without reducing the fluidity of the polymer additive solution 4. Therefore, it is considered that the polishing speed of the base material 7 can be improved by applying the polishing slurry 5.

As such a polymer additive 2, one or more water-soluble organic polymers can be applied. Specifically, for example, polycarboxylic acid and polycarboxylic acid salt, polyacrylic acid and polyacrylic acid salt, salt of formalin condensate of naphthalenesulfonic acid, polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, etc. are applied as the polymer additive 2. However, the present invention is not limited to these. Examples of the salt that can be used as the polymer additive 2 include sodium salt, potassium salt, ammonium salt and the like.

The weight average molecular weight (Mw) of the polymer additive 2 is preferably 400 or more and 45,000, more preferably 1200 or more and 15,000 or less. By setting the weight average molecular weight of the polymer additive 2 within the above range, the polishing rate of the base material 7 is further improved.

Further, the abrasive 3 can further contain an oxidizing agent. Specifically, a component that produces a permanganate ion when dissolved in water is preferable as an oxidant, and examples thereof include potassium permanganate and sodium permanganate. When the polishing slurry 5 containing the abrasive 3 containing such an oxidizing agent is applied to the polishing of the base material 7, the surface of the base material 7 is oxidized and modified, so that the polishing speed of the base material 7 is increased. Is expected to improve.

Further, the content of the polymer additive 2 in the abrasive 3 is preferably 0.01% by mass or more and 10% by mass or less, and more preferably 0.1% by mass or more and 3. It is prepared so as to be 0% by mass or less. By setting the content of the polymer additive 2 with respect to the abrasive grains 1 in the abrasive 3 within the above range, the polishing rate of the base material 7 is further improved. The content of the polymer additive 2 with respect to the abrasive grains 1 in the polishing slurry 5 in which the polishing material 3 is mixed with water is calculated as follows. First, the content of the abrasive grains 1 in the polishing slurry 5 is determined by a dry weight method in which a fixed amount of the polishing slurry 5 is dried at 80°C. In addition, the type of polymer additive 2 is specified by infrared spectrophotometry. Further, sulfuric acid and hydrogen peroxide solution are added to a certain amount of polishing slurry 5 and heated to dissolve manganese oxide and other abrasive grains 1, and then the total organic carbon content (TOC) is measured. Next, the content of the polymer additive 2 in the polishing slurry 5 is determined from the obtained total organic carbon amount and the type of the specified polymer additive 2. Then, the content of the polymer additive 2 with respect to the abrasive grain 1 can be calculated from the content of the abrasive grain 1 and the content of the polymer additive 2 in the obtained abrasive slurry 5.

The pH of the polishing slurry 5 is preferably 3 or more and 9 or less. By setting the pH of the polishing slurry 5 within the above range, the polishing rate of the base material 7 is further improved. For adjusting the pH of the polishing slurry 5, for example, an aqueous solution of an inorganic acid or an inorganic base such as sulfuric acid, hydrochloric acid, nitric acid, sodium hydroxide, potassium hydroxide or ammonia can be appropriately used.

Further, the polishing slurry 5 is prepared so that the content of the abrasive grains 1 is preferably 0.1% by mass or more and 35% by mass or less, and more preferably 1.0% by mass or more and 10% by mass or less. By setting the content of the abrasive grains 1 in the polishing slurry 5 within the above range, the polishing rate of the base material 7 is further improved.

As described above, the abrasive 3 and the polishing slurry 5 according to the embodiment have excellent polishing performance, and the base material 7 can be produced at an excellent polishing rate.

In the above-described embodiment, the abrasive 3 and water are mixed to prepare the polishing slurry 5, but the method for preparing the polishing slurry 5 is not limited. For example, the abrasive grains 1 may be dispersed in the polymer additive solution 4 in which the polymer additive 2 is previously dissolved in water to prepare the polishing slurry 5.

Further, in the polishing slurry 5, a part of the water mixed with the polishing material 3 may be replaced with a water-soluble organic low molecular compound such as alcohol within a range not impairing the essence of the present invention. In addition, the polishing slurry 5 contains additives such as a dispersant, a pH stabilizer that imparts a buffering action, and an agent that prevents the generation of algae, mold, bacteria, etc. (however, polycarboxylic acid and polycarboxylic acid salt, polycarboxylic acid Acrylic acid and polyacrylic acid salts, salts of naphthalenesulfonic acid formalin condensate, polyvinyl alcohol, polyethylene glycol and polyvinyl pyrrolidone are excluded) can be appropriately contained.

Further, in the above-described embodiment, the polishing method using the single-sided polishing machine in which the lower surface side of the base material 7 is the surface to be polished has been described, but the direction of the surface to be polished is not limited. For example, the upper surface side of the base material 7 may be arranged as a surface to be polished, or a double-sided polishing machine for simultaneously polishing the upper and lower surfaces of the base material 7 may be used.

(Example 1)
Abrasive grain 1 (MnO ₂ , average particle diameter (d50): 0.4 μm), polymer additive 2 (sodium polyacrylate, weight average molecular weight Mw=1200), oxidizing agent (potassium permanganate) and water (pure) Water) was weighed so that the mass ratio was 2.0:0.005:2.8:95.195, and these were mixed. Next, a 0.005 mol·dm ⁻³ sulfuric acid aqueous solution was added to adjust the pH to 7.0, and thereby a polishing slurry 5 was obtained. As the polymer additive 2, a polymer additive solution 4 previously prepared was used.

(Example 2)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the weight average molecular weight Mw of the polymer additive solution 4 was changed to 8000.

(Example 3)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the weight average molecular weight Mw of the polymer additive solution 4 was changed to 15000.

(Example 4)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the weight average molecular weight Mw of the polymer additive solution 4 was changed to 250,000.

(Examples 5 to 9)
A polishing slurry 5 was obtained in the same manner as in Example 2 except that the compounding ratios of the polymer additive solution 4 and water (deionized water) were changed.

(Example 10)
To the polishing slurry 5 (before pH adjustment) prepared in Example 2, 0.001 mol·dm ⁻³ sodium hydroxide aqueous solution was added to adjust the pH to 9.0 to obtain polishing slurry 5.

(Examples 11 to 13)
The polishing slurry 5 prepared in Example 2 was further added with a 0.0005 mol·dm ⁻³ sulfuric acid aqueous solution to change the pH, to obtain the polishing slurry 5.

(Example 14)
Abrasive slurry 5 was obtained in the same manner as in Example 1 except that polymer additive 2 was changed to ammonium polycarboxylate (weight average molecular weight Mw=10000).

(Example 15)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the polymer additive 2 was changed to polyethylene glycol (weight average molecular weight Mw=400).

(Example 16)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the polymer additive 2 was changed to polyvinylpyrrolidone (weight average molecular weight Mw=45000).

(Example 17)
Abrasive slurry 5 was obtained in the same manner as in Example 1 except that polymer additive 2 was changed to sodium naphthalenesulfonate formalin condensate (weight average molecular weight Mw=5000).

(Examples 18 to 20)
A polishing slurry 5 was obtained in the same manner as in Example 2 except that the compounding rates of the abrasive grains 1 and water (deionized water) were changed.

(Examples 21 and 22)
Abrasive slurry 5 was obtained in the same manner as in Example 2 except that the mixing ratios of the oxidizing agent (potassium permanganate) and water (deionized water) were changed.

(Example 23)
Abrasive slurry 5 was obtained in the same manner as in Example 2, except that the average particle diameter (d50) of abrasive grain 1 was changed to 0.08 μm.

(Example 24)
Abrasive slurry 5 was obtained in the same manner as in Example 2, except that the average particle size (d50) of abrasive grain 1 was changed to 3.0 μm.

(Example 25)
A polishing slurry 5 was obtained in the same manner as in Example 2 except that the abrasive grain 1 was changed to Mn ₂ O ₃ (average particle diameter (d50): 1.7 μm).

(Example 26)
A polishing slurry 5 was obtained in the same manner as in Example 2 except that the abrasive grains 1 were changed to Mn ₃ O ₄ (average particle diameter (d50): 1.0 μm).

(Comparative Example 1)
A polishing slurry 5 was obtained in the same manner as in Example 1 except that the polymer additive 2 was not used.

(Comparative example 2)
Abrasive slurry 5 was obtained in the same manner as in Example 1 except that sodium oxalate (molecular weight: 134) was used instead of polymer additive 2.

(Comparative example 3)
Polishing slurry 5 was obtained in the same manner as in Example 1 except that trisodium citrate (molecular weight 258) was used instead of polymer additive 2.

(Evaluation 1: polishing speed)
The base material 7 was polished using the polishing slurry 5 obtained in Examples 1 to 3 described above. As the base material 7, a 4H—SiC substrate having a diameter of 3 inches (7.62 cm) and an off angle of 4° was used, and the Si surface of the lapped substrate was polished. As the polishing device, a single-sided polishing machine BC-15 manufactured by M.T. Co. was used. SUBA #600 manufactured by Nitta Haas was used as the polishing pad 6 attached to the bottom plate of the polishing apparatus, the rotation speed of the bottom plate was set to 60 rpm, and the peripheral speed was set to 7163 cm/min. The carrier rotation speed was set to 60 rpm and the peripheral speed was set to 961 cm/min. The supply amount of the polishing slurry 5 per minute was 0.2 dm ^−3, and a load of 3 psi (about 2.07×10 ⁴ Pa) was applied to carry out chemical mechanical polishing (CMP). The polishing time was 3 hours, and the polishing rate (nm/min) was calculated based on the difference in mass of the base material 7 before and after polishing and the density of silicon carbide (3.10 g·cm ⁻³ ). The results are shown in Table 1.

(Evaluation 2: polishing performance)
After the CMP of Evaluation 1 described above, the surface roughness Ra of the base material 7 was measured based on "arithmetic mean roughness Ra" of JIS B0601:2013 and used as an index of polishing performance. Specifically, the surface of the substrate 7 was measured at 5 points using a white light interferometer (NewView7300) manufactured by ZYGO, and the average value of the obtained values was calculated as Ra. The measurement conditions were as follows: objective lens: 50 times, measurement range: 0.14 mm×0.11 mm, averaging count: 16, high pass filter lower limit: 27.5 μm, filter type: Gaussian spline. The results are shown in Table 1.

(Evaluation 3: Deterioration resistance of polishing slurry 5)
The polishing rate and the surface were evaluated in the same manner as in Evaluations 1 and 2 using the polishing slurry after the polishing of Evaluation 1 described above in Examples 2, 6, 16 and 17 and Comparative Examples 1 to 3 was continuously performed for 24 hours. The roughness Ra was measured. The results are shown in Table 1.

Further effects and modifications can be easily derived by those skilled in the art. As such, the broader aspects of the present invention are not limited to the specific details and representative embodiments shown and described above. Therefore, various modifications may be made without departing from the spirit or scope of the general inventive concept defined by the appended claims and their equivalents.

1 Abrasive Grain 2 Polymer Additive 3 Abrasive Material 4 Polymer Additive Solution 5 Polishing Slurry 6 Polishing Pad 7 Base Material

Claims (9)

It comprises a polymer additive having a weight average molecular weight of 1200 or more and 15000 or less and abrasive grains for polishing a substrate made of silicon carbide,
The abrasive grains is seen including a manganese oxide,
The polymeric additive is selected from the group comprising polycarboxylic acids and polycarboxylic acid salts, polyacrylic acid and polyacrylic acid salts, salts of naphthalenesulfonic acid formalin condensates, polyvinyl alcohol, polyethylene glycol and polyvinylpyrrolidone. 1 or more water-soluble organic polymer including, abrasive. A polymer additive having a weight average molecular weight of 1200 or more and 15000 or less,
Abrasive grains for polishing a substrate that is silicon carbide,
Consists of an oxidant,
The abrasive grains is seen including a manganese oxide,
The polymeric additive is selected from the group comprising polycarboxylic acids and polycarboxylic acid salts, polyacrylic acid and polyacrylic acid salts, salts of naphthalenesulfonic acid formalin condensates, polyvinyl alcohol, polyethylene glycol and polyvinylpyrrolidone. 1 or more water-soluble organic polymer including, abrasive. The abrasive according to claim 2, wherein the oxidizing agent contains a component that produces permanganate ions when dissolved in water. The average particle size of the abrasive grains is 3.0μm or less than 0.08 .mu.m, abrasive according to any one of claims 1-3. The abrasive according to any one of claims 1 to 5 , wherein the content of the polymer additive is 0.01% by mass or more and 10% by mass or less based on 100% by mass of the abrasive grains. The manganese oxide comprises manganese dioxide, abrasive according to any one of claims 1-5. And abrasive material according to any one of claims 1-6, comprising water, abrasive slurry. The polishing slurry according to claim 7 , which has a pH of 3 or more and 9 or less. The content of the abrasive grains is not more than 35 mass% 0.1 mass%, polishing slurry according to claim 7 or 8.

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