Fluorinated cleaning fluid mixtures

Abstract

The cleaning fluid includes at least two fluid components, a first fluid component being at least one of a hydrofluorothioether or a chlorinated hydrofluoroolefin, or an isomer of a hydrochlorofluoroolefin, and a second fluid component being an alcohol having 1 to 5 carbon atoms, The cleaning fluid provides enhanced particulate contaminant removal, improved particle redeposition reduction, or a combination thereof, as compared to cleaning fluids including fluorinated fluids.

Description

Summary of the Invention

[0001] Disclosed herein is a fluorinated cleaning fluid mixture comprising at least one fluorinated fluid and an alcohol. Also disclosed is a method for cleaning using the fluorinated cleaning fluid mixture.

[0002] In some embodiments, the cleaning fluid comprises a first fluid component comprising at least one of a hydrofluorothioether or a chlorinated hydrofluoroolefin, or an isomer of a hydrochlorofluoroolefin, and a second fluid component comprising at least one alcohol having 1 to 5 carbon atoms, The cleaning fluid provides enhanced particulate contaminant removal, improved particle redeposition reduction, or a combination thereof, as compared to cleaning fluids comprising a fluorinated fluid.

[0003] Also disclosed is a method for cleaning an article. In some embodiments, the method includes providing an article to be cleaned having at least one surface having at least one contaminant, providing a cleaning fluid as described above, and contacting the substrate surface with the cleaning fluid. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0004] Cleaning fluids are used in a wide range of applications. Hydrocarbon cleaning fluids, such as mixtures of aromatics (e.g., benzene and toluene) or alkanes (e.g., hexane and petroleum ether), or gasoline, are useful cleaning agents, but these materials are flammable and therefore dangerous to use as cleaning agents. Other solvents, such as chlorinated solvents, have been developed that provide good cleaning performance and are non-flammable, but these materials have drawbacks. Hydrofluoroether fluids are widely used in solvent precision cleaning applications, at least in part, due to their good cleaning performance, zero ozone depletion potential, low global warming potential, and low toxicity. Also, because hydrofluoroether fluids are often non-flammable, they can be used safely in a wide range of applications.

[0005] As articles become more complex, cleaning and contaminant removal become more difficult. Cleaning and contaminant removal can be particularly challenging for complementary metal oxide semiconductor (CMOS) components with relatively high pixel density. In such components, any particles, organic residues, or water stains resulting from wafer dicing, die attach, and assembly processes can significantly and adversely affect the quality of the output image. Therefore, improved cleaning fluid formulations that can provide better cleaning performance and improved particle removal and / or particle redeposition prevention efficiency are desirable. Thus, there remains a need for cleaning fluids that have desirable cleaning properties and are non-flammable, non-toxic, and environmentally friendly.

[0006] Disclosed herein is a cleaning fluid that is a mixture of fluids that provides the desired performance characteristics of improved particle removal, reduced particle redeposition, and is non-flammable, as well as environmentally friendly and non-toxic.

[0007] In some embodiments, the cleaning fluid comprises at least two fluid components. A first fluid component comprises one or more isomers of hydrofluorothioethers, chlorinated hydrofluoroolefins, or hydrochlorofluoroolefins. A second fluid component comprises an alcohol containing 1 to 5 carbon atoms. Methods of cleaning a substrate using the cleaning fluid are also disclosed.

[0008] As used herein, "fluoro" (with respect to a group or moiety, such as in "fluoroalkylene" or "fluoroalkyl" or "fluorocarbon") or "fluorinated" means (i) partially fluorinated, having at least one hydrogen atom bonded to a carbon, or (ii) fully fluorinated.

[0009] As used herein, "perfluoro" (e.g., with respect to a group or moiety, such as in "perfluoroalkylene" or "perfluoroalkyl" or "perfluorocarbon") or "fully fluorinated" means completely fluorinated, such that, unless otherwise indicated, there are no carbon-bonded hydrogen atoms available for replacement with fluorine.

[0010] As used herein, the group "-R f " is used in accordance with common usage in the chemical arts to refer to a fluoroalkyl group. f "-" refers to a fluoroalkylene group.

[0011] The terms "room temperature" and "ambient temperature" are used interchangeably and refer to a temperature in the range of 20°C to 25°C.

[0012] The term "alkyl" refers to a monovalent group that is a radical of an alkane that is a saturated hydrocarbon. The alkyl can be linear, branched, cyclic, or combinations thereof.

[0013] The term "olefin" is used herein as is well understood in the chemical arts and refers to a molecule having an olefin group, i.e., a carbon-carbon double bond (-C=C-), which may be terminal or non-terminal. Groups having an olefin group include chlorinated hydrofluoroolefins, which are olefin groups having a chlorine atom, two hydrogen atoms, and a fluorinated group attached thereto; hydrochlorofluoroolefins, which are olefin groups having a chlorine atom, a fluorine atom, a hydrogen atom, and a fluorinated group attached thereto; fully fluorinated olefins, which are olefin groups in which all hydrogen atoms are replaced with fluorine atoms; and hydrofluoroolefins, which are olefin groups containing at least one hydrogen atom plus a fluorine atom.

[0014] As used herein, the term "ether" refers to a a -OR b refers to a compound of the type aand R b is an alkyl group or a fluorinated alkyl group. The term "thioether" refers to an ether compound in which an oxygen is replaced with a sulfur atom. As used herein, the term "hydrofluorothioether" refers to an ether compound in which R a -SR b refers to a thioether of the type, a is an alkyl group, and R b is a fluorinated alkyl group, typically a perfluoroalkyl group.

[0015] Disclosed herein is a cleaning fluid comprising a mixture of fluid components. In some embodiments, the cleaning fluid comprises at least two fluid components. The cleaning fluid comprises a first fluid component comprising one or more isomers of hydrofluorothioethers, chlorinated hydrofluoroolefins, or hydrochlorofluoroolefins. The second fluid component comprises an alcohol comprising 1 to 5 carbon atoms. Each of these components is described in more detail below.

[0016] In some embodiments, the first fluid component is a hydrofluorothioether of Structure 1: [ka] (In the formula, R 1 is a non-fluorinated alkyl group having 1 to 3 carbon atoms; R f 1 is a fluorinated or perfluorinated group containing 2 to 6 carbon atoms, optionally including one or more catenated heteroatoms. In some embodiments, R 1 is an alkyl group having one carbon atom; R f 1 -CR f 3 R f 4 F group, R f 3 and R f 4 is independently a perfluorinated alkyl group having 1 to 3 carbon atoms. In some embodiments, R f3 and R f 4 is a perfluorinated alkyl group having one carbon atom.

[0017] In other embodiments, the first fluid component comprises a chlorinated hydrofluoroolefin of structure 2. [ka]

[0018] The cis nomenclature is used herein and is equivalent to the Z nomenclature. Chlorinated hydrofluoroolefins are commercially available as CELEFIN-1233z from Central Glass Co., Ltd. Tokyo, Japan. Although the cis isomer is shown in the structure, it is well understood in the chemical arts that some trans isomers may also be present in the fluid.

[0019] In other embodiments, the first fluid comprises a hydrochlorofluoroolefin or a mixture of hydrochlorofluoroolefins. The first fluid comprises at least one of the two isomers of hydrochlorofluoroolefin of structure 3; [ka] At least one of two isomers of hydrochlorofluoroolefin of structure 4; [ka] or a mixture of two, three or all four of its isomers.

[0020] A mixture of isomers of structures 3 and 4 is commercially available as AMOLEA AS-300 from (AGC) Asahi Glass Company, Tokyo, Japan.

[0021] The first fluid component is the major component of the cleaning fluid, hi some embodiments, the first fluid component comprises 85-99.9% by weight of the cleaning fluid.

[0022] The cleaning fluid also includes at least a second fluid component. The second fluid component is an alcohol of Structure 5: [ka] (In the formula, R 2 is an alkyl group having 1 to 5 carbon atoms.

[0023] A wide range of alcohols of structure 5 are suitable. In some embodiments, the second fluid component is R 2 wherein the alkyl group has 1 to 4 carbon atoms. The choice of alcohol can affect the properties of the cleaning fluid. A first class of cleaning fluid compositions are cleaning fluids that have improved particle removal compared to cleaning fluids that include fluorinated fluids. A second class of cleaning fluids have improved particle redeposition reduction compared to cleaning fluids that include fluorinated fluids.

[0024] In some embodiments of the first class of cleaning fluids, the second fluid component is R 2 is an alkyl group having 2-3 carbon atoms. Examples of suitable alcohols are ethanol, n-propanol, and isopropanol. In some embodiments, the second fluid component includes isopropanol. The cleaning fluid may also include a third fluid component, or another additive. In some embodiments, the third fluid component includes an alcohol or a hydrofluoroether. Examples of hydrofluoroethers include, for example, 3M NOVEC 7100 Engineered Fluid and AGC ASAHIKLIN AE-3000. As discussed above, the first class of cleaning fluids exhibit improved particle removal compared to cleaning fluids including fluorinated fluids.

[0025] In some embodiments of the second class of cleaning fluids, the second fluid component is R 2is an alkyl group having 4 carbon atoms. Examples of suitable alcohols are the isomers of butanol: n-butanol (1-butanol); sec-butanol; iso-butanol (2-methyl-1-propanol); and tert-butanol. The cleaning fluid may also include a third fluid component, or another additive. In some embodiments, the third fluid component includes an alcohol or a hydrofluoroether. Examples of hydrofluoroethers include, for example, 3M NOVEC 7100 Engineered Fluid and AGC ASAHIKLIN AE-3000. As discussed above, the second class of cleaning fluids exhibit improved particle redeposition reduction compared to cleaning fluids including fluorinated fluids.

[0026] As noted above, the cleaning fluids of the present disclosure have a wide range of desirable properties: The cleaning fluids are non-flammable Suitable tests for flammability are well understood in the cleaning fluid art.

[0027] The cleaning fluid of the present disclosure is also environmentally friendly. This means that the cleaning fluid can have a low impact on the environment. In this regard, the fluorinated compounds of the present disclosure can have a global warming potential (GWP, 100 years ITH) of less than 500, 300, 200, 100, 50, 10, or less than 1. As used herein, GWP is a relative measure of the global warming potential of a compound based on the structure of the compound. The GWP of a compound was defined by the Intergovernmental Panel on Climate Change (IPCC) in 1990 and revised in 2007, and is calculated as the warming caused by 1 kilogram of compound emission relative to the warming caused by 1 kilogram of CO2 emission over a specific integration time horizon (ITH).

number

[0028] In this formula, a iis the radiative forcing (change in radiative flux through the atmosphere due to the IR absorbance of that compound) per unit mass increase of the compound in the atmosphere, C is the atmospheric concentration of the compound, τ is the atmospheric lifetime of the compound, t is time, and i is the compound of interest. A commonly accepted ITH is 100 years, which represents a compromise between short-term effects (20 years) and long-term effects (500 years or more). The concentration of an organic compound, i, in the atmosphere is assumed to follow pseudo-first-order kinetics (i.e., exponential decay). The concentration of CO2 over the same time interval incorporates a more complex model of exchange and removal of CO2 from the atmosphere (the Bern carbon cycle model).

[0029] Methods for cleaning articles are also disclosed herein. In some embodiments, the methods for cleaning articles include providing an article to be cleaned having at least one surface with at least one contaminant, providing a cleaning fluid as described above, and contacting the substrate surface with the cleaning fluid. The cleaning fluid can be used in either gaseous or liquid state (or both), and any of the known techniques for "contacting" the substrate can be used. For example, a liquid cleaning composition can be sprayed, brushed, or spin-coated onto the substrate, a gaseous cleaning composition can be sprayed over the substrate, or the substrate can be placed in either a gaseous or liquid composition. High temperature, ultrasonic energy, and / or agitation can be used to facilitate cleaning. In some embodiments, the method further includes removing the cleaning fluid from the substrate surface by evaporating the cleaning fluid, or removing the substrate from immersion in the cleaning fluid.

[0030] Various solvent cleaning techniques are described in Barbara and Edward Kanesburg, Handbook of Critical Cleaning: Cleaning Agents and Systems, edited by CRC Press, pages 123-127 and 363-372 (2011); and BN Ellis in Cleaning and Contamination of Electronics Components and Assemblies, Electrochemical Publications Limited, Ayr, Scotland, pages 182-94 (1986).

[0031] Both organic and inorganic substrates can be cleaned by the cleaning method of the present disclosure. Representative examples of substrates include metals, ceramics, glass, semiconductors, polycarbonates, polystyrene, acrylonitrile-butadiene-styrene copolymers, synthetic nonwoven materials, natural fibers (and fabrics derived from natural fibers), such as cotton, silk, fur, suede, leather, linen and wool, synthetic fibers (and fabrics), such as polyester, rayon, acrylic, nylon and blends thereof, fabrics containing blends of natural and synthetic fibers, and composites of the aforementioned materials. This process can be useful for precision cleaning of optical and electronic components, subassemblies, or devices, such as circuit boards, wafers and integrated circuit chips (including those based on Si, Ge and Si / Ge semiconductors), CMOS components, display components, optical or magnetic media, UV or EUV photomasks (such as those used in semiconductor photolithography), and various medical devices.

[0032] In some embodiments, the cleaning process of the present disclosure can dissolve or remove most of the contaminants from the surface of the substrate. For example, it can remove materials such as light hydrocarbon contaminants; high molecular weight hydrocarbon contaminants such as mineral oil and grease; fluorocarbon contaminants such as perfluoropolyether, bromotrifluoroethylene oligomers (gyroscope fluids), and chlorotrifluoroethylene oligomers (hydraulic oils, lubricants); silicone oils and greases; solder flux; particulates; and other contaminants encountered in cleaning precision, electronic, metal, and medical equipment. In some embodiments, the process can be used to remove hydrocarbon contaminants (especially light hydrocarbon oils), fluorocarbon contaminants, and organic and inorganic particulates.

[0033] As discussed above, the cleaning fluids of the present invention exhibit various desirable properties, such as improved particle removal compared to cleaning fluids comprising fluorinated fluids, improved reduction in particle redeposition compared to cleaning fluids comprising fluorinated fluids, or a combination of properties.

[0034] The method for cleaning the articles can be carried out in a variety of ways. In some embodiments, the cleaning is performed manually, while in other embodiments, the cleaning is performed using an automated process. As is well understood in the art, a wide range of cleaning machines can be used in the cleaning process. EXAMPLES

[0035] These examples are for illustrative purposes only and are not intended to limit the scope of the appended claims. All parts, percentages, ratios, etc. in the examples and elsewhere herein are by weight unless otherwise indicated.

[0036] [Table 1]

[0037] Test Method Cleaning performance: Particle removal Tests were conducted using the solvent mixtures to determine the cleaning performance of the fluids. The cleaning tests were conducted on heavily soiled CMOS (complementary metal oxide semiconductor) sensors that contain high pixel densities. These sensors are known to be extremely difficult to clean to be essentially free of particulate contaminants.

[0038] A precision solvent cleaning system (SK-04Y-6008 custom-made cleaning system made by YMPT, Thailand) was used to clean the CMOS sensor using the process outlined in Process 1 below. [Table 2]

[0039] The cleaning performance of each cleaning fluid composition was judged based on the percentage of particles originally present on the CMOS surface that were removed by the cleaning fluid after the cleaning process was completed. The percentage of particles removed was determined by optical microscopy of the CMOS sensor before and after cleaning.

[0040] First, the original (heavily soiled) CMOS sensor was inspected using an optical microscope and a series of pre-cleaning images were recorded. The CMOS sensor was then cleaned in a precision cleaning system using the process and specified solvent / surfactant combination described above. After cleaning, the CMOS sensor was inspected again under an optical microscope and post-cleaning images were recorded to determine the number of particles remaining on the sensor. In this way, the particle removal rate (%) after cleaning of the CMOS sensor was determined. The average of two samples was reported. The cleaning performance was characterized by the following criteria:

[0041] [Table 3]

[0042] Cleaning performance: Particle redeposition According to theory, particle cleaning performance depends on two processes: (1) particle removal, and (2) particle redeposition. Process (2) is believed to be important for overall cleaning performance. Therefore, the following experiments were designed to measure the particle redeposition performance of fluids.

[0043] Test solutions were prepared. Silicon nitride particles (Si3N4, with an average particle size of 1.5 micrometers) were then mixed into each test solution (concentration: 0.01 grams of particles / liter of fluid) and ultrasonically agitated for 1 hour. A pre-cleaned bare silicon wafer (4 inch (10 centimeter) diameter) was then immersed into each test solution mixture, with each wafer immersed for 3 seconds, followed by a 4 second hold at full immersion, and each wafer removed and allowed to dry for 3 seconds. The total particle count (number of particles deposited on each wafer) was measured with a microscope (Keyence VH-ZST). Results are reported according to the following criteria:

[0044] [Table 4]

[0045] Working Example: Examples E1-E5 and Comparative Examples CE1-CE2: Particle Removal Test A series of fluids and fluid mixtures were tested using the particle removal test method described above, and the results are shown in Table 1 below.

[0046] [Table 5]

[0047] Examples E6 to E8: Particle redeposition test A series of fluids and fluid mixtures were tested using the Particle Redeposition Test Method described above. Example E6 is an HFTE based fluid with the results shown below in Table 2. Example E7 is an AS-300 based fluid with the results shown below in Table 3. Example E8 is a 7100 based fluid with the results shown below in Table 4.

[0048] [Table 6]

[0049]

Table 7

[0050]

Table 8

Claims

1. A cleaning fluid comprising: A first fluid component comprising a hydrofluorothioether of Structure 1: 【Chemistry 1】 (In the formula, R １ is a non-fluorinated alkyl group having 1 to 3 carbon atoms; R ｆ １ is a fluorinated or perfluorinated group containing 2 to 6 carbon atoms, optionally containing one or more catenated heteroatoms; Chlorinated hydrofluoroolefins of structure 2: 【Chemistry 2】 At least one of two isomers of hydrochlorofluoroolefins of structure 3: 【Chemistry 3】 At least one of two isomers of hydrochlorofluoroolefins of structure 4: 【Chemistry 4】 or a mixture thereof; and A second fluid component comprising at least one alcohol having structure 5: 【Chemistry 5】 (In the formula, R ２ is an alkyl group having 1 to 5 carbon atoms. and a second fluid component comprising: A cleaning fluid, the cleaning fluid providing enhanced particulate contaminant removal, improved particle redeposition reduction, or a combination thereof, as compared to a cleaning fluid comprising a fluorinated fluid.

2. The first fluid component is a hydrofluorothioether of Structure 1: (In the formula, R １ is an alkyl group having one carbon atom, R ｆ １ is -CR ｆ ３ R ｆ ４ F group, R ｆ ３ and R ｆ ４ are independently a perfluorinated alkyl group having 1 to 3 carbon atoms. The cleaning fluid of claim 1 comprising:

3. R ｆ ３ and R ｆ ４ 3. The cleaning fluid of claim 2, wherein is a perfluorinated alkyl group having 1 carbon atom.

4. The cleaning fluid of claim 1 , wherein the first fluid component comprises 85 to 99.9% by weight of the cleaning fluid.

5. The second fluid component is R ２ 2. The cleaning fluid of claim 1, comprising an alcohol, wherein is an alkyl group having 1 to 4 carbon atoms.

6. The second fluid component is R ２ The cleaning fluid of claim 5, comprising an alcohol, wherein is an alkyl group having from 2 to 3 carbon atoms.

7. The cleaning fluid of claim 6 , wherein the second fluid component comprises isopropanol, and the cleaning fluid provides improved particle removal as compared to cleaning fluids comprising fluorinated fluids.

8. The cleaning fluid of claim 7 further comprising at least one third fluid component, said third fluid component comprising an alcohol.

9. The second fluid component is R ２ 2. The cleaning fluid of claim 1 comprising an alcohol wherein is an alkyl group having 4 carbon atoms.

10. 10. The cleaning fluid of claim 1, wherein the second fluid component comprises butanol, and the cleaning fluid provides improved particle redeposition reduction as compared to cleaning fluids comprising fluorinated fluids.

11. The cleaning fluid of claim 10 further comprising at least one third fluid component, said third fluid component comprising an alcohol.

12. The cleaning fluid of claim 1 , wherein the cleaning fluid is non-flammable.

13. 1. A method of cleaning an article, comprising the steps of: Providing an article to be cleaned having at least one surface having at least one contaminant thereon; A cleaning fluid comprising: A first fluid component comprising a hydrofluorothioether of Structure 1: 【Chemistry 6】 (In the formula, R １ is a non-fluorinated alkyl group having 1 to 3 carbon atoms; R ｆ １ is a fluorinated or perfluorinated group containing 2 to 6 carbon atoms, optionally containing one or more catenated heteroatoms; Chlorinated hydrofluoroolefins of structure 2: 【Chemistry 7】 At least one of two isomers of hydrochlorofluoroolefins of structure 3: 【Chemistry 8】 At least one of two isomers of hydrochlorofluoroolefins of structure 4: 【Chemistry 9】 or a mixture thereof; and A second fluid component comprising at least one alcohol having structure 5: 【Chemistry 10】 (In the formula, R ２ is an alkyl group having 1 to 5 carbon atoms. A second fluid component comprising: providing a cleaning fluid comprising: contacting the substrate surface with the cleaning fluid; A method comprising:

14. The method of claim 13 , wherein contacting the substrate surface with the cleaning fluid comprises applying the cleaning fluid by brushing, spraying, or spin coating.

15. The method of claim 13 , wherein contacting the substrate surface with the cleaning fluid comprises immersing the substrate in the cleaning fluid.

16. The method of claim 13 further comprising removing the cleaning fluid from the substrate surface.

17. The method of claim 16 , wherein removing the cleaning fluid from the substrate surface comprises evaporating the cleaning fluid or removing the substrate from immersion in the cleaning fluid.

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