Circulating cooling liquid for semiconductor etching apparatus

Abstract

To provide a liquid for circulation cooling of a semiconductor etching device, which not only has relatively good heat exchange performance but also can satisfy requirements for electrical performance of a cooling liquid in a semiconductor device, has relatively good thermal stability, hardly evaporates, is environment-friendly, and is safe for workers.SOLUTION: At least one organosilicon compound, wherein a chemical formula of the organosilicon compound is (R1) 3Si - [OSiR2R3] n-OSi (R4) 3, R1, R2, R3, R4 are each independently selected from an alkyl group or an alkoxy group, 2 ≤ n ≤ 5, and a relative permittivity ε r, a volume resistivity ρ r, a dynamic viscosity μ, and a density ρ g of the cooling liquid satisfy a relational expression of 28 ≤ 3log ρ r - ε r (μ / ρ g) ≤ 32.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to the field of cooling media, and more particularly to circulating cooling liquids for semiconductor etching equipment, and more particularly to screening methods for semiconductor device applications and circulating cooling liquids for semiconductor etching equipment. [Background technology]

[0002] During semiconductor dry etching, plasma etching generates a large amount of heat on the wafer. To prevent deformation or cracking of the semiconductor material due to temperature rise during the process, temperature control is required. The wafer must be effectively clamped by the electrostatic chuck at all times in high vacuum, plasma, halogen, and other environments, so the temperature of the electrostatic chuck must be controlled. Generally, electrostatic chucks are maintained at a constant temperature mainly by cooling, which maintains the wafer at a constant temperature on the electrostatic chuck and improves process stability.

[0003] Currently, cooling an electrostatic chuck requires the assistance of an external liquid to reduce its temperature. The cooling liquid is transported from a cooling device to an etching device via piping, and then circulates through the etching device's internal piping to cool the electrostatic chuck inside the device. In this application scenario, the liquid directly contacts the charged part of the electrostatic chuck. If the liquid's electrical properties do not meet the requirements, it is likely to cause electrical breakdown inside the machine body, seriously affecting its use. Commonly used coolants in the related art are fluorine-containing coolants or silicon coolants. Fluorine-containing coolants have a low boiling point, are prone to evaporation, and are harmful to the environment and personnel. Commonly used silicon coolants have relatively good high-temperature resistance, but suffer from the problem of being unable to balance heat exchange performance and electrical performance. Therefore, in order to meet the needs of semiconductor etching devices, a thorough consideration of coolants is required. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention was made based on the inventor's discovery and understanding of the following facts and problems: In a semiconductor etching apparatus, the cooling liquid directly contacts the charged portion of the electrostatic chuck, so higher electrical performance is required for the cooling liquid, but conventional cooling liquids cannot effectively achieve a balance between the requirements for heat exchange efficiency, fluidity, electrical performance, and environmental protection. [Means for solving the problem]

[0005] The present invention aims to solve, at least to some extent, one of the technical problems in the related art. To this end, the present invention provides a circulating cooling fluid for a semiconductor etching apparatus, the cooling fluid comprising at least one organosilicon compound, the organosilicon compound having the chemical formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, R1, R2, R 3、 R4 is independently selected from alkyl groups or alkoxy groups, and 2≦n≦5; The relative dielectric constant ε of the circulating cooling liquid r , volume resistivity ρ r , dynamic viscosity μ and density ρ g is 28≦3logρ r -ε r (μ / ρ g )≦32.

[0006] In the present invention, the dynamic viscosity μ and the density ρ g The dynamic viscosity μ and density ρ of the coolant measured at 25°C g Refers to...

[0007] Optionally, 2≦n≦4.

[0008] Optionally, 29≦3 log ρ r -ε r (μ / ρ g )≦31.5.

[0009] Optionally, R1, R2, R3 or R4 has 1 to 6 carbon atoms.

[0010] Optionally, R2 and / or R3 are methyl groups.

[0011] Optionally, R1, R2, and R3 are methyl groups, R4 is not a methyl group, and n is 2 or 3.

[0012] The present invention further provides an application of the circulating cooling liquid for semiconductor etching equipment in semiconductor equipment.

[0013] Optionally, the circulating cooling liquid is used to cool an electrostatic chuck.

[0014] The present invention further provides a method for screening a circulating coolant for a semiconductor etching apparatus, the method comprising: The relative permittivity ε of the selected circulating coolant r , volume resistivity ρ r , dynamic viscosity μ and density ρ g wherein the selected circulating coolant contains at least one organosilicon compound having the formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, where R1, R2, R 3、 Step a, wherein each R4 is independently selected from an alkyl group or an alkoxy group, and 2≦n≦5; 3logρ r -ε r (μ / ρ g Step b: calculating the value of The selected circulating coolant is 28≦3 log ρ r -ε r (μ / ρ g and c) if the temperature is less than or equal to 32, using the circulating coolant as a coolant for a semiconductor device.

[0015] Optionally, R1, R2, R3 or R4 has 1 to 6 carbon atoms. [Effects of the Invention]

[0016] The circulating cooling liquid for a semiconductor etching apparatus according to the present invention has the chemical formula (R1)3Si-[OSiR2R3] n The organosilicon compound of -OSi(R4)3 is used as the cooling liquid, and the organosilicon compound has a high boiling point, relatively good thermal stability, is not easily evaporated, is environmentally friendly, and is safe for workers. The inventors have found from experimental results that the circulating cooling liquid of the present invention has a log ρ of 28≦3logρ r -ε r (μ / ρ g )≦32, the coolant not only has a relatively good heat exchange performance, but also can meet the requirements for the electrical performance of the coolant in the semiconductor device. DETAILED DESCRIPTION OF THE INVENTION

[0017] The following examples of the present invention will be described in detail. The examples are illustrative and are intended to illustrate the present invention, but should not be construed as limiting the present invention.

[0018] An embodiment of the present invention provides a circulating cooling fluid for a semiconductor etching apparatus, comprising at least one organosilicon compound, the organosilicon compound having the chemical formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, R1, R2, R3, and R4 are each independently selected from alkyl groups or alkoxy groups, and 2≦n≦5; The relative dielectric constant ε of the circulating cooling liquid r , volume resistivity ρ r , dynamic viscosity μ and density ρ g is 28≦3logρ r -ε r (μ / ρ g )≦32.

[0019] In the circulating cooling liquid for the semiconductor etching apparatus according to the embodiment of the present invention, the chemical formula is (R1)3Si-[OSiR2R3] nThe organosilicon compound of -OSi(R4)3 is used as the coolant, and the organosilicon compound has a high boiling point, good thermal stability, is not easily evaporated, is environmentally friendly, and is safe for workers. Experimental results show that the circulating coolant of the present invention has a log ρ of 28≦3. r -ε r (μ / ρ g )≦32, the coolant not only has a relatively good heat exchange performance, but also can meet the requirements for the electrical performance of the coolant in the semiconductor device.

[0020] 3logρ r -ε r (μ / ρ g ) in μ / ρ g The item is related to the heat exchange efficiency of the coolant in the machine body, μ / ρ g The larger the value, the lower the fluidity of the coolant and the lower the heat exchange efficiency. g is expected to be as small as possible. r , logρ r The items are closely related to the electrical performance of the coolant, and the relative permittivity ε r The larger the relative permittivity εr, the higher the charge storage capacity of the coolant, which makes it easier for the electric field distribution of the electrostatic chuck of the machine body to deviate during operation, affecting the etching effect of the machine body. Therefore, in practical applications, the smaller the relative permittivity εr, the more preferable it is. r The smaller the volume resistivity ρ, the higher the charge conductivity. During the circulation process, the coolant is more likely to cause damage to the charged parts of the machine body. r If ρ is too large, static electricity buildup is likely to occur during the flow process, which in turn is likely to cause electrical breakdown inside the machine body. r -ε r (μ / ρ g If ) is too low, the fluidity of the cooling liquid is low and the heat exchange efficiency is relatively low, but 3logρ r -ε r (μ / ρ gIf the temperature is too high, the cooling liquid is prone to static electricity buildup, which can easily cause electrical breakdown inside the machine body. Therefore, the present invention provides a circulating cooling liquid with a temperature of 28≦3 log ρ r -ε r (μ / ρ g )≦32, it is possible to effectively achieve both heat exchange performance and electrical performance.

[0021] In some embodiments, R1, R2, R3, or R4 has 1 to 6 carbon atoms.

[0022] In a specific embodiment, R1, R2, R3 or R4 may have 1, 2, 3, 4, 5 or 6 carbon atoms.

[0023] In a preferred embodiment, the R1, R2, R3 or R4 has 1 to 3 carbon atoms.

[0024] In the embodiment of the present invention, by limiting the carbon atoms of the groups R1, R2, R3, or R4 in the organosilicon compound to 6 or less, the cooling liquid can obtain relatively good heat exchange performance and electrical performance. If the number of carbon atoms is too large, the dielectric constant of the cooling liquid will decrease, which is advantageous for improving the electrical performance of the cooling liquid. However, if the number of carbon atoms is too large, the branched chain of the organosilicon compound will be too long, which will reduce the density of the material and reduce the 3logρ of the cooling liquid. r -ε r (μ / ρ g ) exceeds the control range of the embodiment of the present invention, which is disadvantageous for improving the heat transfer performance of the cooling liquid.

[0025] In a specific embodiment, the formula (R1)3Si-[OSiR2R3] n n in —OSi(R4)3 is 2, 3, 4, or 5.

[0026] In a preferred embodiment, 2≦n≦4.

[0027] In the embodiments of the present invention, optimizing the value n of the repeating unit [OSiR2R3] is beneficial for the cooling liquid to have both excellent electrical properties and excellent heat exchange performance. If the value n is too small, i.e., the degree of polymerization is too low, the flash point of the organosilicon compound will be too low, posing a safety risk. If the value n is too large, i.e., the degree of polymerization is too high, the viscosity of the cooling liquid will increase significantly, increasing its density and reducing the fluidity of the cooling liquid, which is detrimental to the cooling liquid maintaining good heat exchange performance.

[0028] In a specific embodiment, 3logρ r -ε r (μ / ρ g ) are 28, 28.5, 29, 29.5, 30, 30.5, 31, 31.5, and 32.

[0029] In a preferred embodiment, 29≦3 log ρ r -ε r (μ / ρ g )≦31.5.

[0030] In the present embodiment, 3logρ r -ε r (μ / ρ g Optimizing the value of ) is beneficial to the coolant obtaining better heat exchange performance and electrical performance, and when used to cool a semiconductor device, the electrostatic chuck can maintain excellent temperature stability and improve the etching effect.

[0031] In a preferred embodiment, R2 and / or R3 are methyl groups.

[0032] In a preferred embodiment, R1, R2, and R3 are methyl groups, R4 is not a methyl group, and n is 2 or 3.

[0033] In an embodiment of the present invention, the chemical formula is (R1)3Si-[OSiR2R3] nThe organosilicon compound of -OSi(R4)3 may be prepared by a conventional method, for example, by hydrolysis and condensation reaction of alkoxysilane under acid catalysis.

[0034] Embodiments of the present invention further provide for use as a circulating cooling liquid in a semiconductor etching apparatus in a semiconductor manufacturing facility.

[0035] In some embodiments, the circulating cooling liquid is used to cool an electrostatic chuck.

[0036] An embodiment of the present invention further provides a screening method for a circulating coolant in a semiconductor etching apparatus, the method comprising: The relative permittivity ε of the selected circulating coolant r , volume resistivity ρ r , dynamic viscosity μ and density ρ g wherein the selected circulating coolant contains at least one organosilicon compound having the formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, where R1, R2, R 3、 Step a, wherein each R4 is independently selected from an alkyl group or an alkoxy group, and 2≦n≦5; 3logρ r -ε r (μ / ρ g Step b: calculating the value of The selected circulating coolant is 28≦3 log ρ r -ε r (μ / ρ g and c) if the circulating coolant is less than or equal to 32, using the circulating coolant as a circulating coolant for a semiconductor etching apparatus.

[0037] In some embodiments, R1, R2, R3, or R4 has 1 to 6 carbon atoms.

[0038] In the screening method for the circulating coolant of a semiconductor etching apparatus according to the embodiment of the present invention, the relative dielectric constant ε of the circulating coolant is r , volume resistivity ρr , dynamic viscosity μ and density ρ g and 3logρ r -ε r (μ / ρ g By calculating the value of 28≦3logρ, it is possible to quickly determine whether a candidate circulating coolant is applicable to a semiconductor device, providing a fast and effective screening method for selecting an appropriate circulating coolant for a semiconductor device. r -ε r (μ / ρ g )≦32, the circulating coolant has relatively good fluidity, and not only meets the heat exchange performance requirements, but also meets the electrical performance requirements of the circulating coolant in the semiconductor device, making it less likely to accumulate static electricity and preventing electrical breakdown inside the machine body.

[0039] The present invention will be described below with reference to specific examples. Note that these examples are merely illustrative and are not intended to limit the present invention in any manner.

[0040] Example 1 The circulating cooling liquid for the semiconductor etching apparatus of this embodiment contains an organosilicon compound having the chemical formula (CH3)3Si-[OSiCH3CH3]3-OSi(CH3)3.

[0041] After replacing the air in the flask with nitrogen gas, 516 g of ethoxysilane was added, and then 3.4 g of sulfuric acid was added dropwise at room temperature. The mixture was heated to 70°C and stirred for 5 hours to react. After removing the acid, the mixture was rotary evaporated at 115°C for 3 hours to obtain the product (CH3)3Si-[OSiCH3CH3]3-OSi(CH3)3.

[0042] The relative dielectric constant ε of the circulating cooling liquid in this embodiment r , volume resistivity ρ r , dynamic viscosity μ and density ρ g The results are shown in Table 1.

[0043] The calculation gives 3logρ r -ε r (μ / ρ g)=29.52.

[0044] Examples 2 to 10 Examples 2-10 are used to illustrate the circulating cooling fluid disclosed in the present invention, and include most of the operation steps in Example 1, with the difference being that the organosilicon compound has the formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, the n values ​​are different, R1, R2, and R used in Examples 2 to 10 3、 R4, n and the relative permittivity ε of the circulating cooling liquid r , volume resistivity ρ r , dynamic viscosity μ and density ρ g is shown in Table 1.

[0045] Comparative Examples 1 to 6 Comparative Examples 1-6 are used to illustrate the circulating cooling fluid disclosed in the present invention, and include most of the operation steps in Example 1, with the difference being that the organosilicon compound has the chemical formula (R1)3Si-[OSiR2R3] n -OSi(R4)3, the n values ​​are different, R1, R2, and R used in Comparative Examples 1 to 6 3、 R4, n and the relative permittivity ε of the circulating cooling liquid r , volume resistivity ρ r , dynamic viscosity μ and density ρ g is shown in Table 1.

[0046] Performance measurement The performance of the circulating cooling liquid for the semiconductor etching equipment was measured. (1) Electrostatic evaluation: The cooling liquid was circulated using a magnetic pump at a flow rate of 4 L / min, the piping material was PFA, and the pipe diameter was 10 mm. After circulating for 5 minutes, an electrometer was used to measure at a point 2.5 cm in diameter, and the scale of the electrometer was recorded. If it was 0.5 kV or less, it was judged as OK. (2) Heat exchange efficiency: The cooling operation was measured using an ATS ENT-30 machine and verified with a 6kW heat load. Normal temperature control was achieved under the conditions of 20LPM of liquid and 20℃. That is, the temperature fluctuation during the operation process (operating time must be more than 1 hour) is less than ±1℃, and there is no situation where the temperature control fails and the liquid temperature continuously rises. The heat exchange efficiency verification is judged to be OK, and the smaller the temperature fluctuation, the higher the heat exchange efficiency.

[0047] [Table 1]

[0048] Table 2 shows the performance measurement results of the circulating cooling liquid for the semiconductor etching apparatuses of Examples 1 to 10 and Comparative Examples 1 to 6.

[0049] [Table 2]

[0050] As can be seen from Tables 1 and 2, the relative dielectric constant ε of the circulating cooling liquid of the semiconductor etching apparatus in Examples 1 to 10 r , volume resistivity ρ r , dynamic viscosity μ and density ρ g In both cases, 28≦3logρ r -ε r (μ / ρ g )≦32, and after electrostatic measurement, all were less than 0.5KV. Furthermore, the heat exchange efficiency was able to be maintained at 20°C after a 6kW heat load measurement, with small temperature fluctuations, all being maintained at 1°C or less. This shows good heat exchange efficiency and electrical performance, and can meet the cooling requirements for electrostatic chucks in semiconductor devices.

[0051] However, the relative dielectric constant ε of the circulating cooling liquids in Comparative Examples 1 to 6 r , volume resistivity ρ r , dynamic viscosity μ and density ρ g is 28≦3logρ r -ε r (μ / ρ g)≦32, and the requirements for heat exchange efficiency and electrostatic measurement cannot be met simultaneously. In Comparative Example 1, the n value is too large, the viscosity of the cooling liquid is too high, the fluidity is significantly reduced, the heat exchange efficiency is seriously reduced, the temperature of the liquid rises continuously in the process, and temperature control fails. In Comparative Example 2, the R2 group and R3 group are CF3, so the relative dielectric constant ε of the circulating cooling liquid is r The value of the voltage after electrostatic measurement was as high as 2.7 KV, which does not meet the electrical performance requirements of the cooling liquid for semiconductor devices. n The R1, R2, R3, R4 and n values ​​in -OSi(R4)3 are all within the range of the examples of the present invention, but 3logρ r -ε r (μ / ρ g ) is greater than 32, and the volume resistivity ρ r Because the value of n is too high, the cooling liquid is prone to static electricity accumulation during the flow process, and the voltage value after static electricity measurement is as high as 1.4 KV, which does not meet the electrical performance requirements of the cooling liquid for semiconductor devices. r -ε r (μ / ρ g )≦32, and Comparative Example 4 can meet the electrical performance requirements of the cooling liquid for semiconductor devices, but the heat exchange performance is seriously reduced and the temperature fluctuation is high at 1.9°C. In Comparative Example 5, the organosilicon compound (R1)3Si-[OSiR2R3] n The R1, R2, R3, R4 and n values ​​in -OSi(R4)3 are all within the range of the examples of the present invention, but 3logρ r -ε r (μ / ρ g ) is below the lower limit of control in the embodiment of the present invention, and only meets the electrical performance requirements of the cooling liquid for semiconductor devices, while the heat exchange performance is significantly reduced, with the temperature fluctuation reaching 1.5°C, which cannot meet the requirements. In Comparative Example 6, the R3 group is C7H 15 and the density of the cooling liquid is low, 3logρ r -εr (μ / ρ g ) is 27.86, which is beyond the control range of the embodiment of the present invention. Although the electrical performance can meet the requirements, the heat exchange performance is significantly reduced and the temperature fluctuation is as high as 1.9°C.

[0052] In the present invention, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples" mean that a specific feature, structure, material, or characteristic described with reference to the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, exemplary descriptions of the above terms do not necessarily refer to the same embodiment or example. In addition, the specific features, structures, materials, or characteristics described may be combined in any appropriate manner in any one or more embodiments or examples. Furthermore, unless mutually inconsistent, those skilled in the art may combine and combine different embodiments or examples and features of different embodiments or examples described herein.

[0053] Although the above embodiments have been shown and described, it should be understood that the above embodiments are illustrative and should not be construed as limiting the present invention, and any variations, modifications, substitutions and alterations made to the above embodiments by those skilled in the art fall within the scope of protection of the present invention.

Claims

1. A circulating cooling fluid for a semiconductor etching apparatus, comprising at least one organosilicon compound, the organosilicon compound having the chemical formula (R １ ) ３ Si-[OSiR ２ R ３ ] ｎ -OSi(R ４ ) ３ and R １ , R ２ , R ３、 R ４ are each independently selected from alkyl groups or alkoxy groups, and 2≦n≦5; The relative dielectric constant ε of the circulating cooling liquid ｒ , volume resistivity ρ ｒ , dynamic viscosity μ and density ρ ｇ is 28≦3 log ρ ｒ -ε ｒ (μ / ρ ｇ )≦32.

2. 2. The circulating cooling liquid for a semiconductor etching apparatus according to claim 1, wherein n satisfies the condition 2≦n≦4.

3. 29≦3 log ρ ｒ -ε ｒ (μ / ρ ｇ 2. The circulating cooling liquid for a semiconductor etching apparatus according to claim 1, wherein the temperature is 0.15 to 1.5°C.

4. The R １ , R ２ , R ３ or R ４ 2. The circulating cooling liquid for a semiconductor etching apparatus according to claim 1, wherein the number of carbon atoms is 1 to 6.

5. The R ２ and / or R ３ 2. The circulating cooling liquid for a semiconductor etching apparatus according to claim 1, wherein is a methyl group.

6. The R １ , R ２ , R ３ is a methyl group, and R ４ 6. The circulating cooling liquid for a semiconductor etching apparatus according to claim 5, wherein is not a methyl group, and n is 2 or 3.

7. 7. Use of the circulating cooling liquid for semiconductor etching equipment according to claim 1 in a semiconductor device.

8. 8. The semiconductor device application of claim 7, wherein the circulating cooling liquid is used to cool an electrostatic chuck.

9. 1. A screening method for a circulating coolant in a semiconductor etching apparatus, comprising: The relative permittivity ε of the selected circulating coolant ｒ , volume resistivity ρ ｒ , dynamic viscosity μ and density ρ ｇ wherein the selected circulating coolant comprises at least one organosilicon compound, the organosilicon compound having the chemical formula (R １ ) ３ Si-[OSiR ２ R ３ ] ｎ -OSi(R ４ ) ３ and R １ , R ２ , R ３、 R ４ are each independently selected from an alkyl group or an alkoxy group, and 2≦n≦5; 3 log ρ ｒ -ε ｒ (μ / ρ ｇ a step b of calculating the value of The selected circulating coolant has a value of 28≦3 log ρ ｒ -ε ｒ (μ / ρ ｇ )≦32, step c uses the circulating coolant as a circulating coolant for a semiconductor etching device; 1. A screening method for a circulating coolant in a semiconductor etching apparatus, comprising:

10. The R １ , R ２ , R ３ or R ４ 10. The screening method for a circulating coolant for a semiconductor etching apparatus according to claim 9, wherein the number of carbon atoms in the group is 1 to 6.

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