Aluminum oxide CMP polishing solution for sic substrate and preparation method therefor

Abstract

The present invention relates to an aluminum oxide CMP polishing solution for a SIC substrate and a preparation method therefor. The polishing solution comprises the following raw materials in parts by weight: 8-10 parts of aluminum oxide powder, 8-10 parts of a suspending agent, 8.5-10 parts of a dispersant, 4-5 parts of a pH regulator, 5-6 parts of an oxidizing agent, 4-5 parts of a defoamer, and 75-80 parts of deionized water. The dispersant is one or a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt, isotridecyl phosphate, polyethylene glycol stearate, polyethylene glycol monolaurate, and polyethylene glycol monooleate. In the present invention, full dispersion and stable suspension of aluminum oxide micropowder can be achieved without any agglomeration, such that abnormal scratches can be prevented from being generated in a grinding process and then affecting the polishing quality; in addition, the use of an alkaline polishing solution can effectively protect devices from damage, prolong the service life of the devices, and increase the machining precision.

Description

Alumina CMP polishing liquid for SIC substrate and preparation method thereof Technical Field

[0001] The present invention relates to the technical field of grinding and polishing, in particular to an aluminum oxide CMP polishing liquid for SIC substrates and a preparation method thereof. Background Art

[0002] Third-generation semiconductor materials generally refer to gallium nitride, silicon carbide, zinc oxide, and aluminum oxide, with gallium nitride and silicon carbide being the main representatives. In terms of bandgap, dielectric constant, thermal conductivity, and maximum operating temperature, gallium nitride and silicon carbide offer superior performance and are gradually being applied in fields such as 5G communications, new energy vehicles, and photovoltaics. Although silicon (Si) is currently the most technologically mature, widely used, and market-leading substrate material, its potential has been exhausted in recent years. Regarding power and frequency, while Si-IGBTs have advantages in the high-voltage field, they are not up to par with the high-frequency field. Si-MOSFETs are capable of high-frequency applications but are limited in voltage. SiC-MOSFETs perfectly address the difficulty of achieving both high and high voltage on silicon substrates.

[0003] At present, with the gradual increase in applications in high voltage, high frequency and high temperature fields, third-generation semiconductor substrates represented by silicon carbide and gallium nitride increasingly need to adopt more efficient production and quality to meet market needs.

[0004] Prior art patent No. CN115418170A discloses a process for processing SIC substrates. Alumina powder and silicon carbide powder are used as abrasives, along with dispersants, surfactants, defoamers, pH regulators, and antioxidants. A polishing slurry is then prepared to process the SIC substrate surface. However, the SIC substrates can be severely scratched, resulting in poor surface quality. Furthermore, the addition of SIC powder as an abrasive can result in excessively high TTV (Telescopic Temperature / Volume) after polishing.

[0005] The second prior art, patent (patent number: CN115418169A), discloses a process for processing SIC substrates. The process uses silica sol and silicon carbide powder as abrasives, along with dispersants, surfactants, defoamers, pH regulators, and oxidants as additives to create a polishing solution. The SIC substrate surface is then processed. However, the patented SIC substrate can be severely scratched. Furthermore, the inclusion of SIC powder as an abrasive in the system can result in excessive surface roughness and deep scratches on the polished SIC substrate.

[0006] A third prior art patent (Patent No. CN112592663A) discloses a process for processing SIC substrates. The process uses alumina powder as an abrasive, along with dispersants, suspending agents, defoamers, and lubricants, to create a polishing slurry. The polishing slurry is then used to process the SIC substrate surface. However, this process only thins the SIC surface and fails to achieve the surface finish required by current SIC packaging processes.

[0007] Summary of the Invention

[0008] In view of the above shortcomings of the existing technology, the present invention provides an aluminum oxide CMP polishing liquid for SIC substrates and a preparation method thereof. Not only can the aluminum oxide powder be fully dispersed and stably suspended without any agglomeration, thereby avoiding abnormal scratches during the grinding process that affect the polishing quality, but the use of an alkaline polishing liquid can effectively protect the equipment from damage, extend the service life of the equipment, and enhance the processing accuracy.

[0009] In order to achieve the above-mentioned and other related purposes, the present invention provides the following technical solutions:

[0010] An aluminum oxide CMP polishing liquid for SIC substrates comprises the following raw materials in parts by weight: 8-10 parts of aluminum oxide powder, 8-10 parts of suspending agent, 8.5-10 parts of dispersant, 4-5 parts of pH regulator, 5-6 parts of oxidant, 4-5 parts of defoaming agent, and 75-80 parts of deionized water.

[0011] Optionally, the alumina powder is one or a mixture of α-Al2O3, β-Al2O3 and γ-Al2O3.

[0012] Optionally, the particle size of the aluminum oxide powder is 0.1-1 μm, preferably 0.1-0.5 μm.

[0013] Optionally, the dispersant is one or a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt, isotridecanol phosphate, polyethylene glycol stearate, polyethylene glycol laurate and polyethylene glycol oleate.

[0014] Optionally, the suspending agent is one or a mixture of agar powder, carrageenan, magnesium aluminum silicate and sodium alginate.

[0015] Optionally, the pH adjuster is one or a mixture of KOH, NAOH and AMP95.

[0016] Optionally, the defoaming agent is one or a mixture of polydimethylsiloxane, polyether-modified silicon.

[0017] Optionally, the oxidant is one or a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

[0018] In order to achieve the above-mentioned and other related objects, the present invention also provides a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate, the method comprising:

[0019] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0020] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0021] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0022] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0023] R5. Add an appropriate amount of pH regulator to the mixed solution D to adjust the pH value, and add a defoaming agent. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

[0024] Optionally, in step R5, the pH value is adjusted to 8.5-10.

[0025] The present invention has the following positive effects:

[0026] 1. The aqueous alkaline alumina polishing liquid and its preparation method provided by the present invention can achieve sufficient dispersion and stable suspension of alumina micropowder without any agglomeration, thereby avoiding abnormal scratches during the grinding process that affect the polishing quality.

[0027] 2. The aqueous alkaline alumina polishing liquid provided by the present invention can achieve better surface effects than other polishing liquids.

[0028] 3. Compared with the alumina grinding fluid which adopts an acidic system and causes greater damage to the equipment, the present invention adopts an alkaline polishing fluid, which can effectively protect the equipment from damage, extend the service life of the equipment and enhance the processing accuracy.

[0029] 4. The aqueous alkaline alumina polishing liquid provided by the present invention can achieve a surface roughness of the SIC substrate of less than 0.2 nm and a processing efficiency higher than 1 UM / min. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] FIG1 is a schematic flow chart of the method of the present invention. DETAILED DESCRIPTION

[0031] The following description of exemplary embodiments of the present disclosure is made in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding. These details should be considered as merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0032] Example 1: An aluminum oxide CMP polishing liquid for SIC substrates, the polishing liquid comprising the following raw materials in parts by weight: 8 parts of aluminum oxide powder, 8 parts of suspending agent, 8.5 parts of dispersant, 4 parts of pH regulator, 5 parts of oxidant, 4 parts of defoaming agent, and 75 parts of deionized water.

[0033] In this embodiment, the aluminum oxide powder is a mixture of α-Al2O3 and γ-Al2O3.

[0034] In this embodiment, the particle size of the aluminum oxide powder is 0.1 μm.

[0035] In this embodiment, the dispersant is a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt and isotridecanol phosphate.

[0036] In this embodiment, the suspending agent is a mixture of agar powder and sodium alginate.

[0037] In this embodiment, the pH adjuster is a mixture of KOH and amp95.

[0038] In this embodiment, the defoaming agent is a mixture of polydimethylsiloxane and polyether-modified silicon.

[0039] In this embodiment, the oxidant is a mixture of hydrogen peroxide and sodium hypochlorite.

[0040] In this embodiment, as shown in FIG1 , the present invention provides a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate, the method comprising:

[0041] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0042] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0043] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0044] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0045] R5. Add an appropriate amount of pH regulator to the mixed solution D to adjust the pH value, and add a defoaming agent. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

[0046] In this embodiment, in step R5, the pH value is adjusted to 8.5.

[0047] Example 2: An aluminum oxide CMP polishing liquid for SIC substrates, the polishing liquid comprising the following raw materials in parts by weight: 9 parts of aluminum oxide powder, 9.5 parts of suspending agent, 10 parts of dispersant, 4.5 parts of pH regulator, 5.5 parts of oxidant, 4.5 parts of defoaming agent, and 76 parts of deionized water.

[0048] In this embodiment, the aluminum oxide powder is a mixture of α-Al2O3, β-Al2O3 and γ-Al2O3.

[0049] In this embodiment, the particle size of the aluminum oxide powder is 0.2 μm.

[0050] In this embodiment, the dispersant is a mixture of isotridecanol phosphate, polyethylene glycol stearate, polyethylene glycol laurate and polyethylene glycol oleate.

[0051] In this embodiment, the suspending agent is a mixture of agar powder, carrageenan, magnesium aluminum silicate and sodium alginate.

[0052] In this embodiment, the pH adjuster is a mixture of KOH, NAOH and amp95.

[0053] In this embodiment, the defoaming agent is polydimethylsiloxane.

[0054] In this embodiment, the oxidant is a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

[0055] In this embodiment, as shown in FIG1 , the present invention provides a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate, the method comprising:

[0056] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0057] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0058] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0059] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0060] R5. Add an appropriate amount of pH regulator to the mixed solution D to adjust the pH value, and add a defoaming agent. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

[0061] In this embodiment, in step R5, the pH value is adjusted to 9.

[0062] Example 3: An aluminum oxide CMP polishing liquid for SIC substrates, the polishing liquid comprising the following raw materials in parts by weight: 9 parts of aluminum oxide powder, 8 parts of suspending agent, 9.5 parts of dispersant, 5 parts of pH regulator, 6 parts of oxidant, 5 parts of defoaming agent, and 78 parts of deionized water.

[0063] In this embodiment, the aluminum oxide powder is a mixture of α-Al2O3 and γ-Al2O3.

[0064] In this embodiment, the particle size of the aluminum oxide powder is 0.3 μm.

[0065] In this embodiment, the dispersant is a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt, polyethylene glycol laurate and polyethylene glycol oleate.

[0066] In this embodiment, the suspending agent is a mixture of magnesium aluminum silicate and sodium alginate.

[0067] In this embodiment, the pH adjuster is a mixture of KOH, NAOH and amp95.

[0068] In this embodiment, the defoaming agent is a mixture of polydimethylsiloxane and polyether-modified silicon.

[0069] In this embodiment, the oxidant is a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

[0070] In this embodiment, as shown in FIG1 , a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate comprises:

[0071] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0072] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0073] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0074] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0075] R5. Add an appropriate amount of pH regulator to the mixed solution D to adjust the pH value, and add a defoaming agent. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

[0076] In this embodiment, in step R5, the pH value is adjusted to 9.5.

[0077] Example 4: An aluminum oxide CMP polishing liquid for SIC substrates, the polishing liquid comprising the following raw materials in parts by weight: 8 parts of aluminum oxide powder, 9 parts of suspending agent, 8.5 parts of dispersant, 4.5 parts of pH regulator, 6 parts of oxidant, 5 parts of defoaming agent, and 80 parts of deionized water.

[0078] In this embodiment, the aluminum oxide powder is a mixture of α-Al2O3, β-Al2O3 and γ-Al2O3.

[0079] In this embodiment, the particle size of the aluminum oxide powder is 0.5 μm.

[0080] In this embodiment, the dispersant is a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt, isotridecanol phosphate and polyethylene glycol stearate.

[0081] In this embodiment, the suspending agent is a mixture of agar powder, carrageenan, magnesium aluminum silicate and sodium alginate.

[0082] In this embodiment, the pH adjuster is a mixture of NAOH and amp95.

[0083] In this embodiment, the defoaming agent is a mixture of polydimethylsiloxane and polyether-modified silicon.

[0084] In this embodiment, the oxidant is a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

[0085] In this embodiment, as shown in FIG1 , a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate comprises:

[0086] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0087] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0088] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0089] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0090] R5. Add an appropriate amount of pH regulator to the mixed solution D to adjust the pH value, and add a defoaming agent. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

[0091] In this embodiment, in step R5, the pH value is adjusted to 9.

[0092] Example 5: An aluminum oxide CMP polishing liquid for SIC substrates, the polishing liquid comprising the following raw materials in parts by weight: 10 parts aluminum oxide powder, 9.5 parts suspending agent, 9 parts dispersant, 4 parts pH regulator, 5 parts oxidant, 4 parts defoaming agent, and 80 parts deionized water.

[0093] In this embodiment, the aluminum oxide powder is a mixture of α-Al2O3, β-Al2O3 and γ-Al2O3.

[0094] In this embodiment, the particle size of the aluminum oxide powder is 0.5 μm.

[0095] In this embodiment, the dispersant is a mixture of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt and polyethylene glycol oleate.

[0096] In this embodiment, the suspending agent is a mixture of agar powder, carrageenan, magnesium aluminum silicate and sodium alginate.

[0097] In this embodiment, the pH adjuster is a mixture of KOH, NAOH and amp95.

[0098] In this embodiment, the defoaming agent is polyether-modified silicone.

[0099] In this embodiment, the oxidant is a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

[0100] In this embodiment, as shown in FIG1 , a method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate comprises:

[0101] R1. The suspending agent was mixed with deionized water to form a suspending agent content of 0.1% -10% by mass ratio of the solution to obtain a mixed solution A;

[0102] R2. The alumina powder was gradually and slowly added to the mixed solution A while being ultrasonically stirred for more than 5 minutes to uniformly disperse the alumina powder to obtain a mixed solution B;

[0103] R3. The dispersant was added to the mixed solution B and continued to stir evenly for more than 5 minutes to obtain a mixed solution C;

[0104] R4. The oxidant was added to the mixed solution C while being ultrasonically stirred and ultrasonically stirred for 15 minutes to thoroughly mix the system to obtain a mixed solution D;

[0105] R5. Add an appropriate amount of pH adjuster to the mixed solution D to adjust the pH value, and add a defoamer. Continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates. In this embodiment, in step R5, the adjusted pH value is 9.5.

[0106] Comparative Example 1: An alkaline polishing liquid, which includes the following raw materials in parts by weight: 10 parts of aluminum oxide powder, 5 parts of silicon carbide powder, 1 part of defoaming agent, 1 part of dispersant, 2 parts of surfactant, 2 parts of pH regulator, 0.1 part of antioxidant, and 50 parts of deionized water.

[0107] Comparative Example 2: An alkaline polishing liquid, which includes the following raw materials in parts by weight: 20 parts of aluminum oxide powder, 6 parts of silicon carbide powder, 5 parts of defoaming agent, 5 parts of dispersant, 6 parts of surfactant, 3 parts of pH regulator, 0.5 parts of antioxidant, and 60 parts of deionized water.

[0108] Performance indicators of the aluminum oxide CMP polishing liquid for SIC substrates of Examples 1-5 and the alkaline polishing liquid of Comparative Examples 1-2

[0109] From the above table, we can see that the polishing liquid removal rate of the present application is higher than that of Comparative Examples 1 and 2, which improves production efficiency, has smaller surface roughness, is smoother, and has better stability. It can effectively protect equipment from damage, extend the service life of the equipment and enhance processing accuracy.

[0110] In summary, the present invention can not only achieve sufficient dispersion and stable suspension of alumina micropowder without any agglomeration, thereby avoiding abnormal scratches during the grinding process and affecting the polishing quality, but also uses alkaline polishing liquid to effectively protect the equipment from damage, extend the service life of the equipment and enhance processing accuracy.

[0111] The above specific embodiments do not constitute a limitation on the scope of protection of this disclosure. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this disclosure shall be included within the scope of protection of this disclosure.

Claims

1. An aluminum oxide CMP polishing liquid for SIC substrate, characterized in that: The polishing liquid comprises the following raw materials in parts by weight: 8-10 parts of aluminum oxide powder, 8-10 parts of suspending agent, 8.5-10 parts of dispersing agent, 4-5 parts of pH value regulator, 5-6 parts of oxidant, 4-5 parts of defoaming agent, and 75-80 parts of deionized water.

2. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The alumina powder is one or a mixture of α-Al2O3, β-Al2O3 and γ-Al2O3.

3. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 2, characterized in that: The particle size of the aluminum oxide powder is 0.1-1 μm, preferably 0.1-0.5 μm.

4. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The dispersant is one or a mixture of several of fatty alcohol ether phosphate, fatty alcohol ether phosphate potassium salt, isotridecanol phosphate, polyethylene glycol stearate, polyethylene glycol laurate and polyethylene glycol oleate.

5. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The suspending agent is one or a mixture of agar powder, carrageenan, magnesium aluminum silicate and sodium alginate.

6. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The pH value adjuster is one or a mixture of KOH, NAOH and amp95.

7. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The defoaming agent is one or a mixture of polydimethylsiloxane and polyether modified silicon.

8. The aluminum oxide CMP polishing liquid for SIC substrate according to claim 1, characterized in that: The oxidant is one or a mixture of hydrogen peroxide, potassium permanganate and sodium hypochlorite.

9. A method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate, characterized in that: The method comprises: R1. The suspending agent is mixed with deionized water to form a solution having a suspending agent content of 0.1%-10% by mass to obtain a mixed solution A; R2. The alumina powder is gradually and slowly added to the mixed solution A, and ultrasonic and stirring are performed at the same time. The ultrasonic stirring time is more than 5 minutes, so that the alumina powder is evenly dispersed to obtain a mixed solution B; R3. Add the dispersant to the mixed solution B and continue stirring evenly for more than 5 minutes to obtain a mixed solution C; R4. The oxidant was added to the mixed solution C and ultrasonically stirred for 15 minutes to mix the system thoroughly to obtain a mixed solution D; R5. Add an appropriate amount of pH adjuster to the mixed solution D to adjust the pH value, add a defoamer, and continue stirring and dispersing for a certain period of time to obtain an aluminum oxide CMP polishing liquid for SIC substrates.

10. The method for preparing an aluminum oxide CMP polishing liquid for a SIC substrate according to claim 9, characterized in that: In step R5, the pH value is adjusted to 8.5-10.

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