Rough grinding fluid applied to diamond substrate

Abstract

The invention is applied to the technical field of semiconductor processing, and discloses a coarse grinding fluid applied to a diamond substrate, which comprises the following components: a diamond grinding material, a suspending agent, a dispersing agent, an antirust agent, a lubricant, a pH regulator and deionized water, the coarse grinding liquid applied to the diamond substrate comprises the following components in percentage by weight: 0.1 to 5 percent of diamond grinding material, 0.01 to 0.5 percent of suspending agent, 0.01 to 5 percent of dispersing agent, 0.1 to 8 percent of antirust agent, 0.5 to 5 percent of lubricating agent, 0.01 to 0.5 percent of pH regulator and 74 to 95 percent of deionized water. According to the coarse grinding liquid applied to the diamond substrate, the type 3 or more diamond grinding materials are selected, the particle size D50 is 20-60 microns, the particle size D100 is smaller than 100 microns, and the surface of the substrate can be smoother while a surface material of the diamond substrate is removed.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor processing, in particular to a rough grinding liquid applied to a diamond substrate and a preparation method thereof. Background Art

[0002] In today's semiconductor technology field, diamond substrates are gradually becoming one of the key basic materials due to their excellent physical and chemical properties. Diamond has extremely high hardness, excellent thermal conductivity, good chemical stability and wide bandgap. These characteristics make diamond substrates have great application potential in high-power electronic devices, high-frequency electronic devices, optoelectronic devices and other fields. However, to give full play to the advantages of diamond substrates, their processing quality is crucial. Among them, rough grinding is an important link in the processing of diamond substrates. Traditional grinding fluids often face many severe challenges when rough grinding diamond substrates. First of all, uneven abrasive dispersion is a common problem. In traditional grinding fluids, abrasive particles may gather together for various reasons and cannot be evenly distributed in the grinding fluid. This will not only lead to unstable grinding effects, but also cause local over-grinding or under-grinding on the surface of the diamond substrate, seriously affecting the processing quality. For example, in some cases, scratches, pits and other defects may be formed on the surface of the diamond substrate due to the uneven distribution of abrasives. These defects will reduce the flatness and smoothness of the substrate, which will in turn affect the subsequent production and performance of semiconductor devices. Secondly, poor suspension stability is also a major drawback of traditional grinding fluids. The suspension stability of the abrasive in the grinding fluid is directly related to the continuity and stability of the grinding process. If the abrasive is easy to precipitate, then during the grinding process, the abrasive concentration in the grinding fluid will continue to change, resulting in grinding efficiency and surface roughness being difficult to control. Moreover, frequent stirring of the grinding fluid to prevent abrasive precipitation not only increases the complexity of the operation, but may also introduce additional impurities, further affecting the processing quality. In addition, the easy rusting of the workpiece is also a problem that cannot be ignored by traditional grinding fluids. In the semiconductor processing process, rust prevention of diamond substrates is crucial. Once the substrate rusts, it will not only damage its surface quality, but may also affect subsequent process steps and device performance. The components in traditional grinding fluids may not be able to effectively prevent the diamond substrate from rusting, or its rust prevention effect is not long enough, which brings great risks to the processing of diamond substrates. At the same time, it is difficult for grinding efficiency and surface roughness to reach an ideal state, which is also one of the shortcomings of traditional grinding fluids. Summary of the invention

[0003] The object of the present invention is to provide a rough grinding liquid for diamond substrate and a preparation method thereof, so as to solve the problems of uneven abrasive dispersion, poor suspension stability and easy rusting of workpieces mentioned in the above background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a rough grinding liquid applied to a diamond substrate and a preparation method thereof, wherein the rough grinding liquid applied to the diamond substrate comprises the following components: diamond abrasive, a suspending agent, a dispersing agent, a rust inhibitor, a lubricant, a pH regulator and deionized water, wherein the content of the diamond abrasive in the rough grinding liquid applied to the diamond substrate is 0.1-5wt%, the content of the suspending agent is 0.01-0.5wt%, the content of the dispersing agent is 0.01-5wt%, the content of the rust inhibitor is 0.1-8wt%, the content of the lubricant is 0.5-5wt%, the content of the pH regulator is 0.01-0.5wt%, and the content of the deionized water is 74-95wt%.

[0005] Preferably, the diamond abrasive is selected from Type 3 and above, and the diamond particle size D50 is 20-60um, and D100 is less than 100um.

[0006] Preferably, the suspending agent is one or more of xanthan gum, carbomer, polyacrylic acid, polyurea, lithium aluminum silicate, and bentonite.

[0007] Preferably, the dispersant is one or more of phosphates, polyphosphates, silicates, and polyacrylic acids.

[0008] Preferably, the rust inhibitor is a compound of one or more of alcohol amines, polyol esters, and silane coupling agents.

[0009] Preferably, the lubricant is one or more of ethylene glycol, propylene glycol, and polyethylene glycol.

[0010] Preferably, the pH regulator is one or more of sodium hydroxide, potassium hydroxide, citric acid, boric acid, etc.

[0011] A method for preparing a rough grinding liquid for use on a diamond substrate, the method comprising the following steps:

[0012] S1, preparation stage: accurately weigh the required mass of deionized water, pour it into the prepared container, and then weigh the suspending agent, dispersing agent, rust inhibitor, lubricant and pH adjuster according to the corresponding proportion;

[0013] S2 slowly adds the suspending agent into the deionized water and stirs, and then adds the dispersant, rust inhibitor and lubricant in sequence and stirs continuously during the addition;

[0014] S3, add pH regulator, add slowly while stirring, and use pH meter to monitor the pH value of the solution in real time, and accurately control the amount of pH regulator added according to the required pH range to ensure that the pH value of the coarse grinding liquid reaches the optimal state;

[0015] S4. Slowly add the specified amount of Type 3 and above diamond abrasives. During the process of adding the abrasives, keep the stirring speed constant so that the abrasives can be evenly dispersed into the solution. Use a gradual addition method to avoid local aggregation of the abrasives. Continue stirring for 1-2 hours after adding the abrasives.

[0016] S5. In a sterile and dust-free environment, filter the prepared coarse grinding liquid through a microporous filter membrane or filter screen to remove impurities and large particles, then let the filtered coarse grinding liquid settle or centrifuge it to further purify the coarse grinding liquid to ensure its purity and stability.

[0017] Preferably, the suspending agent in S2 is stirred at 300-500 rpm and 30-50°C.

[0018] Preferably, the pH value in S3 is controlled between 8-10.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the rough grinding liquid applied to the diamond substrate:

[0020] 1. Use type 3 and above diamond abrasives with a particle size of D50 of 20-60um and D100 < 100um to ensure the grinding accuracy. It can avoid over-grinding while removing the surface material of the diamond substrate, making the substrate surface smoother and improving the processing quality;

[0021] Furthermore, the grinding rate can reach 3-20um / h with the cast iron disc, and the surface roughness Sa value can reach 0.1-1um. This excellent surface roughness level meets the high requirements of semiconductor devices for the surface accuracy of diamond substrates, and provides a high-quality foundation for the subsequent production of semiconductor devices.

[0022] 2. During the stirring process, the suspending agent molecules gradually disperse in the water and form a preliminary network structure through the interaction between molecules, which can make the diamond abrasive evenly suspended in the grinding liquid to prevent the abrasive from settling, ensure the stability of the abrasive concentration during the grinding process, and improve the consistency and stability of the grinding effect. The dispersant can fully disperse the abrasive to avoid agglomeration of the abrasive, ensure the uniform distribution of the abrasive particles in the grinding liquid, and further enhance the stability of grinding. The rust inhibitor can form a protective film on the surface of the diamond substrate, effectively preventing oxygen and moisture in the air from contacting the substrate surface, preventing the diamond substrate from rusting, and protecting the surface quality of the substrate;

[0023] Furthermore, by continuously stirring for a period of time each time an additive is added, the additive is fully dissolved and mixed, the dispersant is adsorbed on the surface of the abrasive particles to exert a dispersing effect, the rust inhibitor is soluble in water to prepare for the subsequent rust prevention process, and the lubricant is evenly distributed in the solution. DETAILED DESCRIPTION

[0024] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The invention provides a technical solution: a rough grinding liquid applied to a diamond substrate, the rough grinding liquid applied to the diamond substrate comprises the following components: diamond abrasive, a suspending agent, a dispersing agent, a rust inhibitor, a lubricant, a pH regulator and deionized water, wherein the content of the diamond abrasive in the rough grinding liquid applied to the diamond substrate is 0.1-5wt%, the content of the suspending agent is 0.01-0.5wt%, the content of the dispersing agent is 0.01-5wt%, the content of the rust inhibitor is 0.1-8wt%, the content of the lubricant is 0.5-5wt%, the content of the pH regulator is 0.01-0.5wt%, and the content of the deionized water is 74-95wt%.

[0026] Embodiment 1

[0027] The components include:

[0028] Deionized water: 91.85%;

[0029] Diamond abrasive (type 3 and above, particle size D50 is 25um, D100 < 100um): 4%;

[0030] Suspending agent (polyurea): 0.05%;

[0031] Dispersant (polyacrylic acid and silicate mixed at a ratio of 1:1): 0.5%;

[0032] Rust inhibitor (alcohol amine and polyol ester mixed at a ratio of 1:2): 2%;

[0033] Lubricant (ethylene glycol and propylene glycol mixed at a ratio of 1:1): 1.5%;

[0034] pH adjuster (boric acid): 0.1%.

[0035] Embodiment 2

[0036] The components include:

[0037] Deionized water: 77.1%;

[0038] Diamond abrasive (type 3 and above, particle size D50 is 60um, D100 < 100um): 5%;

[0039] Suspending agent (lithium aluminum silicate): 0.4%;

[0040] Dispersant (phosphate and polyphosphate mixed at a ratio of 2:1): 4%;

[0041] Rust inhibitor (polyol ester and silane coupling agent mixed in a ratio of 1:1): 8%;

[0042] Lubricant (polyethylene glycol): 5%;

[0043] pH adjuster (sodium hydroxide and potassium hydroxide mixed in a ratio of 1:1): 0.5%.

[0044] Embodiment 3

[0045] The components include:

[0046] Deionized water: 83.5%;

[0047] Diamond abrasive (type 3 and above, particle size D50 is 35um, D100 < 100um): 3.5%;

[0048] Suspending agent (bentonite): 0.15%;

[0049] Dispersant (polyphosphate and silicate mixed at a ratio of 3:2): 2.5%;

[0050] Rust inhibitor (alcohol amine, polyol ester and silane coupling agent mixed at a ratio of 1:1:1): 6%;

[0051] Lubricant (ethylene glycol and polyethylene glycol mixed at a ratio of 2:3): 4%;

[0052] pH adjuster (citric acid and boric acid mixed in a ratio of 1:2): 0.35%.

[0053] Embodiment 4

[0054] The components include:

[0055] Deionized water: 87%;

[0056] Diamond abrasive (type 3 and above, particle size D50 is 45um, D100 < 100um): 2.5%;

[0057] Suspending agent (xanthan gum and carbomer mixed at a ratio of 1:2): 0.25%;

[0058] Dispersant (silicate and polyacrylic acid mixed at a ratio of 2:3): 1.8%;

[0059] Rust inhibitor (polyol ester): 4.5%;

[0060] Lubricant (propylene glycol and polyethylene glycol mixed at a ratio of 1:2): 3.5%;

[0061] pH adjuster (sodium hydroxide and citric acid mixed at a ratio of 2:1): 0.45%.

[0062] Embodiment 5

[0063] The components include:

[0064] Deionized water: 79.75%;

[0065] Diamond abrasive (type 3 and above, particle size D50 is 55um, D100 < 100um): 4.5%;

[0066] Suspending agent (polyurea and lithium aluminum silicate mixed at a ratio of 1:1): 0.35%;

[0067] Dispersant (phosphates, polyphosphates and silicates mixed at a ratio of 1:1:1): 3.5%;

[0068] Rust inhibitor (alcoholamine and silane coupling agent mixed at a ratio of 2:1): 7%;

[0069] Lubricant (ethylene glycol, propylene glycol and polyethylene glycol mixed at a ratio of 1:1:2): 4.5%;

[0070] pH adjuster (potassium hydroxide and boric acid mixed at a ratio of 1:3): 0.4%.

[0071] The following table shows the test data of abrasive dispersion uniformity, suspension stability and diamond substrate anti-rust effect of each embodiment;

[0072] Table 1

[0073]

[0074] Table 1 (continued)

[0075]

[0076] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and do not limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are included in the protection scope of the present invention.

Claims

1. A rough grinding liquid for diamond substrate, characterized in that: The rough grinding liquid applied to the diamond substrate comprises the following components: diamond abrasive, suspending agent, dispersing agent, rust inhibitor, lubricant, pH regulator and deionized water. The rough grinding liquid applied to the diamond substrate comprises 0.1-5wt% of diamond abrasive, 0.01-0.5wt% of suspending agent, 0.01-5wt% of dispersing agent, 0.1-8wt% of rust inhibitor, 0.5-5wt% of lubricant, 0.01-0.5wt% of pH regulator and 74-95wt% of deionized water.

2. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The diamond abrasive is selected from Type 3 and above, and the particle size D50 of the diamond is 20-60um, and D100 is less than 100um.

3. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The suspending agent is one or more of xanthan gum, carbomer, polyacrylic acid, polyurea, lithium aluminum silicate and bentonite.

4. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The dispersant is one or more of phosphates, polyphosphates, silicates and polyacrylic acids.

5. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The rust inhibitor is a compound of one or more of alcohol amines, polyol esters and silane coupling agents.

6. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The lubricant is one or more of ethylene glycol, propylene glycol and polyethylene glycol.

7. The rough grinding liquid for diamond substrate according to claim 1, characterized in that: The pH regulator is one or more of sodium hydroxide, potassium hydroxide, citric acid, boric acid, etc.

8. A method for preparing a rough grinding liquid for use on a diamond substrate according to any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: S1, preparation stage: accurately weigh the required mass of deionized water, pour it into the prepared container, and then weigh the suspending agent, dispersing agent, rust inhibitor, lubricant and pH adjuster according to the corresponding proportion; S2 slowly adds the suspending agent into the deionized water and stirs, and then sequentially adds the dispersant, rust inhibitor and lubricant and continues stirring during the addition; S3, add pH regulator, add slowly while stirring, and use pH meter to monitor the pH value of the solution in real time, and accurately control the amount of pH regulator added according to the required pH range to ensure that the pH value of the coarse grinding liquid reaches the optimal state; S4. Slowly add the specified amount of Type 3 and above diamond abrasives. During the process of adding the abrasives, keep the stirring speed constant so that the abrasives can be evenly dispersed into the solution. Use a gradual addition method to avoid local aggregation of the abrasives. Continue stirring for 1-2 hours after adding the abrasives. S5. In a sterile, dust-free environment, the prepared coarse grinding liquid is filtered through a microporous filter membrane or a filter screen to remove impurities and large particles therein, and then the filtered coarse grinding liquid is allowed to settle or centrifuged to further purify the coarse grinding liquid to ensure its purity and stability.

9. The method for preparing a rough grinding liquid for a diamond substrate according to claim 8, characterized in that: The suspending agent in S2 is stirred at 300-500 rpm and 30-50°C.

10. The method for preparing a rough grinding liquid for a diamond substrate according to claim 8, characterized in that: The pH value in S3 is controlled between 8-10.

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