Liquid for circulating cooling of semiconductor etching equipment

Abstract

The invention discloses a liquid for circulating cooling of semiconductor etching equipment, which comprises at least one organic silicon compound, the chemical formula of the organic silicon compound is (R1) 3Si-[OSiR2R3] n-OSi (R4) 3, R1, R2, R3 and R4 are respectively and independently selected from alkyl or alkoxy groups, n is more than or equal to 2 and less than or equal to 5, and n is more than or equal to 2 and less than or equal to 5. And the relative dielectric constant epsilon r, the volume resistivity rho r, the dynamic viscosity mu and the density rho g of the cooling liquid meet the following relational expression: 3log rho r-epsilon r (mu / rho g) is greater than or equal to 28 and less than or equal to 32. The liquid for circulating cooling of the semiconductor etching equipment not only has better heat exchange performance, but also can meet the requirement of the semiconductor equipment on the electrical performance of the cooling liquid, has better heat stability, is not easy to evaporate, and is friendly and safe to the environment and workers.

Description

Technical Field

[0001] In the field of cooling medium technology, this invention relates to a circulating cooling liquid for semiconductor etching equipment, and further to a method for screening circulating cooling liquid for semiconductor etching equipment. Background Technology

[0002] During semiconductor dry etching, plasma etching of wafers generates a significant amount of heat. To prevent deformation and cracking of the semiconductor material due to temperature rise during the process, temperature control is necessary. In high vacuum, plasma, and halogen environments, electrostatic chucks are often used to effectively hold the wafer, thus requiring temperature control of the chucks. Typically, electrostatic chucks are kept at a constant temperature through cooling, ensuring the wafer on the chuck also maintains a constant temperature, thereby improving process stability.

[0003] Currently, cooling electrostatic chucks requires an external liquid cooling system. This liquid is transported from the refrigeration equipment to the etching equipment via pipes, and then circulates within the etching equipment to cool the electrostatic chucks. In this application scenario, the liquid directly contacts the charged parts of the electrostatic chuck. If the liquid's electrical properties are insufficient, it can easily cause electrical breakdown within the machine, severely impacting its operation. Commonly used coolants in related technologies are fluorinated or silicone coolants. Fluorinated coolants have low boiling points and are prone to evaporation, posing hazards to the environment and personnel. While commonly used silicone coolants offer good high-temperature resistance, they suffer from a trade-off between heat transfer and electrical performance. Therefore, it is necessary to conduct in-depth research on coolants to meet the requirements of semiconductor etching equipment. Summary of the Invention

[0004] This invention is based on the inventor's discovery and understanding of the following facts and problems: In semiconductor etching equipment, since the cooling liquid directly contacts the charged part of the electrostatic chuck, higher electrical performance requirements are placed on the cooling liquid, and current cooling liquids cannot effectively balance heat exchange efficiency, fluidity, electrical performance and environmental protection requirements.

[0005] This invention aims to at least partially address one of the technical problems in related technologies. To this end, the present invention provides a circulating cooling liquid for a semiconductor etching apparatus, comprising at least one organosilicon compound having the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where,

[0006] R1, R2, R 3、 R4 are each independently selected from alkyl or alkoxy groups, 2≤n≤5;

[0007] Furthermore, the relative permittivity ε of the circulating cooling liquid... r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The following relationship must be satisfied: 28 ≤ 3logρ r -ε r (μ / ρ g )≤32.

[0008] In this invention, dynamic viscosity μ and density ρ g This refers to the dynamic viscosity μ and density ρ of the coolant measured at 25℃. g .

[0009] Optional, 2≤n≤4.

[0010] Optional, 29≤3logρ r -ε r (μ / ρ g )≤31.5.

[0011] Optionally, the number of carbon atoms in R1, R2, R3 or R4 is 1 to 6.

[0012] Optionally, R2 and / or R3 are methyl groups.

[0013] Optionally, R1, R2, and R3 are methyl groups, R4 is not methyl, and n is 2 or 3.

[0014] The present invention also provides the application of a circulating cooling liquid for semiconductor etching equipment in semiconductor equipment.

[0015] Optionally, the circulating cooling liquid is used to cool the electrostatic chuck.

[0016] The present invention also provides a method for screening circulating coolant for semiconductor etching equipment, comprising the following steps:

[0017] a. Determine the relative permittivity ε of the candidate circulating coolant. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The candidate circulating coolant includes at least one organosilicon compound with the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where R1, R2, R 3、 R4 are each independently selected from alkyl or alkoxy groups, 2≤n≤5;

[0018] b. Calculate 3logρ r -ε r (μ / ρ g The value of );

[0019] c. When the selected circulating coolant satisfies 28≤3logρ r -ε r (μ / ρ g When the temperature is ≤32, this circulating coolant is used as the coolant for semiconductor devices.

[0020] Optionally, the number of carbon atoms in R1, R2, R3 or R4 is 1 to 6.

[0021] The circulating cooling liquid for the semiconductor etching equipment provided by the present invention has the chemical formula (R1)3Si-[OSiR2R3]. n The organosilicon compound -OSi(R4)3 is used as a cooling liquid. Organosilicon compounds have high boiling points, good thermal stability, and are not easily evaporated, making them environmentally friendly and safe for workers. The inventors discovered through experiments that the circulating cooling liquid of this invention satisfies 28 ≤ 3logρ. r -ε r (μ / ρ g When the temperature is ≤32, the coolant not only has good heat exchange performance, but also meets the requirements of the electrical performance of the coolant in semiconductor equipment. Detailed Implementation

[0022] The embodiments of the present invention are described in detail below. These embodiments are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0023] This invention provides a circulating cooling liquid for a semiconductor etching apparatus, comprising at least one organosilicon compound with the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where,

[0024] R1, R2, R3, and R4 are each independently selected from alkyl or alkoxy groups, where 2 ≤ n ≤ 5;

[0025] Furthermore, the relative permittivity ε of the circulating cooling liquid... r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The following relationship must be satisfied: 28 ≤ 3logρ r -ε r (μ / ρ g )≤32.

[0026] The circulating cooling liquid in the semiconductor etching equipment of this invention uses the chemical formula (R1)3Si-[OSiR2R3]. nThe organosilicon compound -OSi(R4)3 is used as a coolant. Organosilicon compounds have high boiling points, good thermal stability, and are not easily evaporated, making them environmentally friendly and safe for workers. Experiments have shown that the circulating cooling liquid of this invention satisfies 28 ≤ 3logρ. r -ε r (μ / ρ g When the temperature is ≤32, the coolant not only has good heat exchange performance, but also meets the requirements of the electrical performance of the coolant in semiconductor equipment.

[0027] In 3logρ r -ε r (μ / ρ g In ), μ / ρ g The term is related to the heat exchange efficiency of the coolant on the machine platform, μ / ρ g The higher the value, the worse the coolant's fluidity and the lower the heat exchange efficiency. In practical applications, the desired efficiency is μ / ρ. g The smaller the better. ε r ,logρ r The term is closely related to the electrical properties of the coolant, specifically the relative permittivity ε. r The larger the relative permittivity ε, the stronger the coolant's ability to store charge, which can easily cause deviations in the electric field distribution of the electrostatic chuck during operation, thus affecting the etching effect. Therefore, in practical applications, the relative permittivity ε... r It's preferable to have as low a value as possible. Volume resistivity ρ r The smaller the volume resistivity ρ, the better the charge conduction performance. However, during the circulation of the coolant, it can easily cause breakdown in the charged parts of the machine. r If the value is too large, static electricity can easily accumulate during the flow process, which can also cause electrical breakdown inside the machine. When 3logρ r -ε r (μ / ρ g When the temperature is too low, the coolant has poor fluidity and low heat exchange efficiency. However, when 3logρ... r -ε r (μ / ρ g When the temperature is too high, static electricity can easily accumulate in the cooling liquid, potentially causing electrical breakdown inside the machine. Therefore, this invention addresses this issue by ensuring that the circulating cooling liquid satisfies 28 ≤ 3logρ. r -ε r (μ / ρ g With a value of ≤32, it achieves an effective balance between heat exchange performance and electrical performance.

[0028] In some embodiments, the number of carbon atoms in R1, R2, R3 or R4 is 1 to 6.

[0029] In specific embodiments, the number of carbon atoms in R1, R2, R3, or R4 can be 1, 2, 3, 4, 5, or 6.

[0030] In a preferred embodiment, the number of carbon atoms in R1, R2, R3 or R4 is 1-3.

[0031] In this embodiment of the invention, limiting the number of carbon atoms in the groups R1, R2, R3, or R4 of the organosilicon compound to six or less enables the cooling liquid to achieve better heat transfer and electrical properties. If the number of carbon atoms is too high, although the dielectric constant of the cooling liquid will decrease, which is beneficial for improving its electrical properties, an excessive number of carbon atoms will cause the branches of the organosilicon compound to be too long, leading to a decrease in the density of the substance and reducing the 3logρ of the cooling liquid. r -ε r (μ / ρ g The value exceeds the control range of the embodiments of the present invention, which is not conducive to improving the heat transfer performance of the cooling liquid.

[0032] In a specific embodiment, the chemical formula is (R1)3Si-[OSiR2R3]. n In -OSi(R4)3, n is 2, 3, 4, or 5.

[0033] In a preferred embodiment, 2 ≤ n ≤ 4.

[0034] In this embodiment of the invention, the preferred value of n for the repeating unit [OSiR2R3] is beneficial for maintaining excellent heat transfer performance while ensuring excellent electrical properties of the cooling liquid. If the value of n is too small, i.e., the polymerization is too small, the flash point of the organosilicon compound is too low, posing a safety risk; if the value of n is too large, i.e., the polymerization is too high, the viscosity and density of the cooling liquid will increase significantly, resulting in poor fluidity and hindering the maintenance of good heat transfer performance of the cooling liquid.

[0035] In a specific embodiment, 3logρ r -ε r (μ / ρ g The values ​​are 28, 28.5, 29, 29.5, 30, 30.5, 31, 31.5, and 32.

[0036] In a preferred embodiment, 29 ≤ 3logρ r -ε r (μ / ρ g )≤31.5.

[0037] In this embodiment of the invention, 3logρ is preferred. r -ε r (μ / ρ gThe value of ) is beneficial to enable the coolant to obtain better heat exchange and electrical performance, and when used for cooling semiconductor equipment, it enables the electrostatic chuck to maintain excellent temperature stability and improves the etching effect.

[0038] In a preferred embodiment, R2 and / or R3 are methyl groups.

[0039] In a preferred embodiment, R1, R2, and R3 are methyl groups, R4 is not a methyl group, and n is 2 or 3.

[0040] The chemical formula in this embodiment of the invention is (R1)3Si-[OSiR2R3] n Organosilicon compounds of -OSi(R4)3 can be prepared using existing techniques. For example, they can be prepared by hydrolysis-condensation reaction using alkoxysilanes as raw materials under acid catalyst conditions.

[0041] This invention also provides an application of a circulating cooling liquid for semiconductor etching equipment in semiconductor equipment.

[0042] In some embodiments, the circulating cooling liquid is used to cool the electrostatic chuck.

[0043] This invention also provides a method for screening circulating coolant in semiconductor etching equipment, comprising the following steps:

[0044] a. Determine the relative permittivity ε of the candidate circulating coolant. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The candidate circulating coolant includes at least one organosilicon compound with the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where R1, R2, R 3、 R4 are each independently selected from alkyl or alkoxy groups, 2≤n≤5;

[0045] b. Calculate 3logρ r -ε r (μ / ρ g The value of );

[0046] c. When the selected circulating coolant satisfies 28≤3logρ r -ε r (μ / ρ g When the temperature is ≤32, this circulating coolant is used as the circulating coolant for the semiconductor etching equipment.

[0047] In some embodiments, the number of carbon atoms in R1, R2, R3 or R4 is 1 to 6.

[0048] The method for screening circulating coolant for semiconductor etching equipment according to embodiments of the present invention involves determining the relative permittivity ε of the circulating coolant. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g And calculate 3logρ r -ε r (μ / ρ g The value of 28 ≤ 3logρ can quickly determine whether the candidate circulating coolant is suitable for semiconductor equipment, providing a fast and effective screening method for selecting the appropriate circulating coolant for semiconductor equipment. When the coolant satisfies 28 ≤ 3logρ r -ε r (μ / ρ g When the temperature is ≤32, the circulating coolant not only has good fluidity to meet the requirements of heat exchange performance, but also meets the requirements of electrical performance of circulating coolant in semiconductor equipment. It is not easy to accumulate static electricity and can avoid electrical breakdown inside the machine.

[0049] The present invention will now be described with reference to specific embodiments. It should be noted that these embodiments are merely descriptive and do not limit the present invention in any way.

[0050] Example 1:

[0051] The circulating cooling liquid for the semiconductor etching equipment in this embodiment includes an organosilicon compound with the chemical formula (CH3)3Si-[OSiCH3CH3]3-OSi(CH3)3.

[0052] After purging the flask with nitrogen, 516g of ethoxysilane was added, followed by the addition of 3.4g of sulfuric acid at room temperature. The mixture was heated to 70℃ and stirred for 5h. After removing the acid, the mixture was rotary evaporated at 115℃ for 3h to obtain the product (CH3)3Si-[OSiCH3CH3]3-OSi(CH3)3.

[0053] The relative permittivity ε of the circulating cooling liquid in this embodiment was tested. r Volume resistivity ρ r Dynamic viscosity μ and density ρ g The test results are shown in Table 1.

[0054] Calculation shows that 3logρ r -ε r (μ / ρ g =29.52.

[0055] Example 2-10

[0056] Examples 2-10 illustrate the circulating cooling liquid disclosed in this invention, including most of the operating steps in Example 1, except that the organosilicon compound has the chemical formula (R1)3Si-[OSiR2R3]. n The groups and n values ​​in -OSi(R4)3 are different:

[0057] The R1, R2, and R used in Examples 2-10 3、 R4, n, and the relative permittivity ε of the circulating cooling liquid. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g As shown in Table 1.

[0058] Comparative Examples 1-6

[0059] Comparative Examples 1-6 illustrate the circulating cooling liquid disclosed in this invention, including most of the operating steps in Example 1, except that the organosilicon compound has the chemical formula (R1)3Si-[OSiR2R3]. n The groups and n values ​​in -OSi(R4)3 are different:

[0060] The R1, R2, and R used in Comparative Examples 1-6 3、 R4, n, and the relative permittivity ε of the circulating cooling liquid. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g As shown in Table 1.

[0061] Performance testing

[0062] The following performance tests were performed on the circulating cooling liquid of the aforementioned semiconductor etching equipment:

[0063] (1) Static electricity assessment: The cooling liquid was circulated using a magnetic pump at a flow rate of 4 L / min. The pipe material was PFA and the pipe diameter was 10 mm. After circulating for 5 minutes, an electrometer was used to test and record the reading at a pipe diameter of 2.5 cm. A reading below 0.5 kV was considered OK.

[0064] (2) Heat exchange efficiency: The ATS ENT-30 machine was used to conduct a refrigeration test and a 6kW heat load was used for verification. If the liquid can achieve normal temperature control at 20LPM and 20℃, that is, the temperature fluctuation during operation (the running time is required to be >1h) is less than ±1℃, and there is no situation where the temperature control fails and the liquid temperature continues to rise, then the heat exchange efficiency verification is OK, and the smaller the temperature fluctuation, the better the heat exchange efficiency.

[0065] Table 1

[0066]

[0067] The performance test results of the circulating cooling liquids for the semiconductor etching equipment in Examples 1-10 and Comparative Examples 1-6 are shown in Table 2.

[0068] Table 2

[0069] Temperature control performance verification Electrostatic test / kV determination Example 1 19.8～20.7℃ 0.3 OK Example 2 20.1～20.9℃ 0.4 OK Example 3 19.6～20.4℃ 0.2 OK Example 4 19.8～20.5℃ 0.3 OK Example 5 19.9～20.5℃ 0.3 OK Example 6 19.9～20.5℃ 0.2 OK Example 7 19.9～20.3℃ 0.2 OK Example 8 19.6～20.6℃ 0.1 OK Example 9 19.9～20.5℃ 0.2 OK Example 10 19.8～20.4℃ 0.2 OK Comparative Example 1 Continued warming 0.3 NG Comparative Example 2 20.1～20.6℃ 2.7 NG Comparative Example 3 19.8～20.4℃ 1.4 NG Comparative Example 4 18.7～20.6℃ 0.2 NG Comparative Example 5 18.9～20.4℃ 0.2 NG Comparative Example 6 18.5～20.4℃ 0.1 NG

[0070] As can be seen from Tables 1 and 2, the relative permittivity ε of the circulating cooling liquid in the semiconductor etching equipment of Examples 1-10 is... r Volume resistivity ρ r Dynamic viscosity μ, density ρ g All satisfy 28≤3logρ r -ε r (μ / ρ g The range requirement of ≤32 is met. After electrostatic testing, the voltage is less than 0.5KV. After a 6kW heat load test, the heat exchange efficiency can be maintained at 20℃ with small temperature fluctuations, all remaining below 1℃. It has good heat exchange efficiency and electrical performance, and can meet the cooling requirements of electrostatic chucks in semiconductor equipment.

[0071] The relative permittivity ε of the circulating cooling liquid in Comparative Examples 1-6 r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The condition 28 ≤ 3logρ cannot be satisfied. r -ε r (μ / ρ g The requirement of n ≤ 32 cannot simultaneously meet the requirements for heat exchange efficiency and electrostatic testing. In Comparative Example 1, the excessively large n value leads to excessively high viscosity of the cooling liquid, significantly reducing its fluidity and causing a severe decrease in heat exchange efficiency. During the process, the liquid continues to heat up, resulting in temperature control failure. In Comparative Example 2, the R2 and R3 groups are CF3, leading to an excessively high relative permittivity ε of the circulating cooling liquid. r The voltage increased significantly, reaching as high as 2.7KV after electrostatic testing, which fails to meet the electrical performance requirements of semiconductor devices for coolant. In Comparative Example 3, although the organosilicon compound (R1)3Si-[OSiR2R3]... n The values ​​of R1, R2, R3, R4, and n in -OSi(R4)3 are all within the range of the embodiments of the present invention, but 3logρ r -ε r (μ / ρ g The volume resistivity ρ of the liquid used for circulating cooling in Comparative Example 3 is greater than 32. rIf the voltage is too high, static electricity can easily accumulate in the coolant during flow, resulting in a voltage value as high as 1.4KV after electrostatic testing, which fails to meet the electrical performance requirements of semiconductor devices. In Comparative Example 4, the value of n is too small and does not meet the control requirement of 28≤3logρ in the embodiments of the present invention. r -ε r (μ / ρ g While Comparative Example 4 meets the requirements for the electrical performance of the coolant in semiconductor devices (≤32), its heat transfer performance is severely degraded, with temperature fluctuations reaching as high as 1.9℃. In Comparative Example 5, although the organosilicon compound (R1)3Si-[OSiR2R3]... n The values ​​of R1, R2, R3, R4, and n in -OSi(R4)3 are all within the range of the embodiments of the present invention, but 3logρ r -ε r (μ / ρ g The temperature is below the lower limit to be controlled in the embodiments of the present invention, which can only meet the requirements of semiconductor devices for the electrical performance of the coolant. The heat transfer performance shows a significant decrease, and the temperature fluctuation reaches 1.5℃, which does not meet the requirements. In Comparative Example 6, the R3 group is C7H. 15 The cooling liquid has a low density, 3logρ r -ε r (μ / ρ g The value is 27.86, which is outside the range that this embodiment of the invention is intended to control. Although the electrical performance can meet the requirements, the heat exchange performance is greatly reduced and the temperature fluctuation is as high as 1.9℃.

[0072] In this invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0073] Although the above embodiments have been shown and described, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Any changes, modifications, substitutions and variations made to the above embodiments by those skilled in the art are within the protection scope of the present invention.

Claims

1. A circulating cooling liquid for a semiconductor etching apparatus, characterized in that, It includes at least one organosilicon compound with the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where, R1, R2, R 3、 R4 are each independently selected from alkyl or alkoxy groups, 2≤n≤5; Furthermore, the relative permittivity ε of the circulating cooling liquid... r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The following relationship must be satisfied: 28 ≤ 3logρ r -ε r (μ / ρ g )≤32.

2. The circulating cooling liquid for the semiconductor etching equipment according to claim 1, characterized in that, 2≤n≤4。 3. The circulating cooling liquid for the semiconductor etching equipment according to claim 1, characterized in that, 29≤3logρ r -e r (m / r) g )≤31.5。 4. The circulating cooling liquid for the semiconductor etching equipment according to claim 1, characterized in that, The number of carbon atoms in R1, R2, R3, or R4 is 1 to 6.

5. The circulating cooling liquid for the semiconductor etching equipment according to claim 1, characterized in that, R2 and / or R3 are methyl groups.

6. The circulating cooling liquid for the semiconductor etching equipment according to claim 5, characterized in that, R1, R2, and R3 are methyl groups, R4 is not a methyl group, and n is 2 or 3.

7. The application of a circulating cooling liquid for semiconductor etching equipment according to any one of claims 1-6 in semiconductor equipment.

8. The application according to claim 7, characterized in that, The circulating cooling liquid is used to cool the electrostatic chuck.

9. A method for screening circulating coolant for semiconductor etching equipment, characterized in that, Includes the following steps: a. Determine the relative permittivity ε of the candidate circulating coolant. r Volume resistivity ρ r Dynamic viscosity μ, density ρ g The candidate circulating coolant includes at least one organosilicon compound with the chemical formula (R1)3Si-[OSiR2R3]. n -OSi(R4)3, where R1, R2, R 3、 R4 are each independently selected from alkyl or alkoxy groups, 2≤n≤5; b. Calculate 3logρ r -ε r (μ / ρ g The value of ); c. When the selected circulating coolant satisfies 28≤3logρ r -ε r (μ / ρ g When the temperature is ≤32, this circulating coolant is used as the circulating coolant for the semiconductor etching equipment.

10. The screening method according to claim 9, characterized in that, The number of carbon atoms in R1, R2, R3, or R4 is 1 to 6.

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