JP6849064B2 - Mask cleaning method and rinse composition for vacuum deposition - Google Patents

Description

The present invention relates to a method for cleaning a mask for vacuum vapor deposition and a rinsing composition.

In recent years, as a flat panel display, a liquid crystal display device and a display device provided with an organic EL element have been attracting attention. Although the liquid crystal display device consumes low power, it requires external lighting (backlight) to obtain a bright screen. On the other hand, a display device provided with an organic EL element does not require a backlight like a liquid crystal display device because the organic EL element is a self-luminous element. Therefore, the display device provided with the organic EL element has a feature of power saving, and also has a feature of high brightness and a wide viewing angle.

The organic EL element has a functional layer including a light emitting layer made of an organic compound between the anode and the cathode. As a method for forming such a functional layer, a gas phase process (also referred to as a dry method) such as a vacuum deposition method or a liquid phase process (wet method) using a solution in which a functional layer forming material is dissolved or dispersed in a solvent is used. Alternatively, a coating method is known (see, for example, Patent Documents 1 to 3).

When the functional layer is formed by vacuum vapor deposition, a mask is brought close to the substrate, and each layer of the cathode, the hole injection layer, the hole transport layer, the light emitting layer, the electron transport layer, and the anode is patterned through the mask. The vapor deposition mask used at this time, especially for fine patterning of the RGB layer, is difficult to manufacture due to its high definition and is very expensive. However, in the pattern formation of the organic layer in the organic EL element, if the same mask is used several times for vapor deposition, organic substances are deposited and adhered on the mask, so that the high-definition mask pattern cannot be accurately transferred to the substrate. Will end up. Therefore, in order to realize a high-definition mask pattern, it is necessary to discard the expensive mask that has been used several times, which is one of the factors that make mass production difficult from the viewpoint of production cost.

Therefore, attempts have been made to reduce the cost by repeatedly using the mask, and a cleaning liquid composition for cleaning various organic substances adhering to the mask in the vacuum vapor deposition process of manufacturing an organic EL element has been proposed. (See, for example, Patent Document 4.).

Patent Document 4 describes that the mask is washed with a cleaning liquid composition and then rinsed with a hydrofluoroether. _{However, "Novec HFE7100" (C 4} F ₉ OCH ₃ ) used as a rinsing solution in Patent Document 4 is decomposed in the presence of, for example, N-methyl-2-pyrrolidinone or N, N-dimethylformamide, and fluorine. Generates ions (see, for example, Patent Document 5). Therefore, in the above method, the mask surface may not be cleaned cleanly.

JP-A-2002-110345 JP-A-2002-305079 Japanese Unexamined Patent Publication No. 2002-313564 Japanese Unexamined Patent Publication No. 2005-162947 Special Table 2009-518857

The present invention has been made to solve the above-mentioned problems, for example, a method for cleaning a mask used in a vacuum vapor deposition step at the time of manufacturing an organic EL element, in which a mask washed with a cleaning composition is rinsed. It is an object of the present invention to provide a cleaning method and a rinsing composition capable of cleaning a mask extremely cleanly without decomposing the active ingredient of the rinsing composition when rinsing with an object.

The cleaning method of the embodiment is a cleaning method of a mask for vacuum deposition, and the mask comprises at least one selected from N-methyl-2-pyrrolidinone (NMP) and N, N-dimethylformamide (DMF). Wash with the washing composition, and the mask after washing is CF ₃ CH _2- O-CF ₂ CHF ₂ (HFE-347pc-f), CHF ₂ CF _2- O-CH ₃ (HFE-254pc), CHF _2- Rinse with a rinse composition containing at least one hydrofluoroether selected from O-CH ₂ CF ₂ CHF ₂ (HFE-356 pcf) and CF ₃ CHFCF _2- O-CH ₂ CF _{3 (HFE-449mec-f).} It is characterized by that.

In the washing method of the embodiment, the ratio of the content of the hydrofluoroether in the rinse composition is preferably 80% by mass or more and 100% by mass or less.

In the cleaning method of the embodiment, the cleaning composition preferably contains N-methyl-2-pyrrolidinone.

In the washing method of the embodiment, the rinse composition preferably contains _{CF 3} CH _2- O-CF ₂ CHF _2.

In the cleaning method of the embodiment, the mask is preferably washed and rinsed at 10 ° C. or higher and 40 ° C. or lower, and more preferably 20 ° C. or higher and 30 ° C. or lower.

In the cleaning method of the embodiment, vacuum deposition is preferably performed in the production of a low molecular weight organic EL device.

In the washing method of the embodiment, it is preferable to dry the mask after rinsing with the rinsing composition.

The rinse composition of the embodiment is a rinse composition for rinsing a mask for vacuum deposition washed with a cleaning composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide. It is selected from CF ₃ CH _2- O-CF ₂ CHF ₂ , CHF ₂ CF _2- O-CH ₃ , CHF _2- O-CH ₂ CF ₂ CHF ₂ and CF ₃ CHFCF _2- O-CH ₂ CF _3. It is characterized by containing at least one hydrofluoroether.

The ratio of the content of the hydrofluoroether in the rinse composition of the embodiment is preferably 80% by mass or more and 100% by mass or less.

In the present specification, the abbreviation of the compound may be written in parentheses after the compound name, and the abbreviation may be used instead of the compound name as necessary. Further, in the present specification, the reference numeral of "~" represents a range of a numerical value or more and a numerical value or less described after that.

According to the cleaning method and rinsing composition of the present embodiment, for example, in cleaning the mask used in the vacuum vapor deposition step during the production of an organic EL element, when rinsing the mask washed with the cleaning composition with the rinsing composition. , The mask can be washed extremely cleanly without decomposition of the active ingredient of the rinse composition.

It is a figure explaining the manufacturing method of the organic EL display device. It is a figure which shows typically the formation mode of the light emitting layer through a mask.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The cleaning method of the present embodiment is, for example, a method of cleaning the mask used in the vacuum vapor deposition step at the time of manufacturing an organic EL element, and includes a cleaning step, a rinsing step, and a drying step. In the washing method of the present embodiment, in the washing step, the mask is washed with a washing composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide. Then, in the rinsing step, the mask after washing with the washing composition is subjected to a rinsing composition containing at least one hydrofluoroether selected from HFE-347pc-f, HFE-254pc, HFE-356pcf and HFE-449mec-f. Rinse with. Then, if necessary, a drying step is performed to dry the mask.

In the washing method of the present embodiment, the specific hydrofluoroether contained in the rinsing composition is decomposed even in the presence of N-methyl-2-pyrrolidinone or N, N-dimethylformamide in the washing composition. Hateful. Therefore, even when the cleaning composition remains on the mask after cleaning, the specific hydrofluoroether in the rinsing composition is not decomposed by the cleaning composition and does not generate fluorine ions. Therefore, the mask surface can be cleaned extremely cleanly.

The mask to be cleaned in the cleaning method of the present embodiment is, for example, the one used in the vacuum vapor deposition step in the manufacturing process of the organic EL display device described below.

The method of manufacturing the organic EL display device will be outlined below with reference to FIGS. 1 and 2 in a vacuum vapor deposition process using a mask. A TFT (thin film transistor) and a transparent electrode are formed on the glass substrate, and a hole transport layer is further formed. The glass substrate 1 on which the TFT, the transparent electrode, and the hole transport layer are formed is carried into the vacuum chamber with the surface to be processed of the glass substrate 1 facing downward. In the vacuum chamber, a light emitting layer corresponding to each primary color R, G, B as a color display device is formed on the glass substrate 1. This step is performed in a separate chamber corresponding to each primary color R, G, B as a color display device. That is, the glass substrate 1 has a vacuum chamber for forming a light emitting layer corresponding to the primary color R, a vacuum chamber for forming a light emitting layer corresponding to the primary color G, and a vacuum for forming a light emitting layer corresponding to the primary color B. It is sequentially transported to the chamber.

In each vacuum chamber, a mask 20 opened in advance according to the shape of the light emitting layer is arranged in the manner shown in FIG. The mask 20 is fixed by a mask frame 21 arranged on the holding table 24.

In each vacuum chamber, as a mask 20, a mask in which only a portion corresponding to a transparent electrode (anode) 11 used for emitting light of a predetermined primary color corresponding to any of the primary colors R, G, and B is opened is opened. It is equipped. Thereby, in each chamber, the light emitting layer corresponding to each primary color can be formed at a predetermined position.

In FIG. 1, the surface of the glass substrate 1 is passed through the opening of the mask by heating and evaporating the material (organic EL material) of the light emitting layer from the vapor deposition source (source) 30 arranged below the holding table 24. The same material is vapor-deposited on the surface. The formation mode of the light emitting layer via the mask 20 is schematically shown in FIG. As shown in FIG. 2, of each transparent electrode (anode) 11, the area other than the transparent electrode forming region corresponding to the corresponding primary color in each chamber is covered with the mask 20. Then, the organic EL material corresponding to the corresponding primary color is heated in the source 30 and vaporized to be vapor-deposited on the glass substrate 1 (to be exact, the hole transport layer) through the opening 20h of the mask 20. .. Examples of the mask material include stainless steel such as SUS, Ni alone, Ni alloys (for example, Fe-Ni alloys and Mg-Ni alloys), and semiconductors such as silicon.

In this thin-film deposition process, various organic substances made of the thin-film deposition material adhere to the mask. Examples of the vapor deposition material include the above-mentioned organic EL material, a hole injection material, a hole transport material, an electron transport material, and the like used in manufacturing an organic EL element. Hole injection materials include copper phthalocyanine (CuPC), poly (3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) composite (PEDOT / PSS), 4,4', 4''. -Tris [phenyl (m-tolyl) amino] triphenylamine (m-MTDATA) and the like can be mentioned. Examples of the hole transport material include triphenylamines (TPD), diphenyl naphthyldiamine (α-NPD), tris (4-carbazoyl-9-ylphenyl) amine (TCTA) and the like. Organic EL materials include bisstyrylbenzene derivatives, tris (8-quinolinolato) aluminum (Alq ₃ ), bis [2- (2-benzoxazolyl) phenolato] zinc (II) (Zn-PBO), rubrene, and dimethyl. Quinacridone, N, N'-dimethylquinacridone (DMQ), 4- (dicyanomethylene) -2-methyl-6- [2- (2,3,6,7-tetrahydro-1H, 5H-benzo [ij] quinolidine- 9-Il) vinyl] -4H-pyran (DCM2) and the like. Electron transport materials include Alq ₃ , 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 2-phenyl-5- (4-biphenylyl) -1,3,4-oxadi. Examples thereof include azole (PBD) and siror derivatives.

In the washing step of the washing method of the present embodiment, the organic matter adhering to the mask is washed with a washing composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide. Examples of the cleaning method include a method of immersing the mask in the cleaning composition and a method of spraying the cleaning composition onto the mask by a jet water stream. Further, ultrasonic cleaning may be used in combination with the mask cleaning, whereby the dissolving ability can be improved and the cleaning time can be shortened. The cleaning composition used in the cleaning step preferably contains N-methyl-2-pyrrolidinone from the viewpoint of detergency.

The content of N-methyl-2-pyrrolidinone or N, N-dimethylformamide in the cleaning composition used in the cleaning step is preferably 80 to 100% by mass from the viewpoint of sufficiently cleaning the mask. It is more preferably ~ 100% by mass, and even more preferably 98-100% by mass. When the cleaning composition contains both N-methyl-2-pyrrolidinone and N, N-dimethylformamide, the total content ratio of these is preferably in the above-mentioned preferable range in that the mask can be sufficiently washed.

The cleaning composition may contain components other than N-methyl-2-pyrrolidinone and N, N-dimethylformamide as long as the effects of the present embodiment are not impaired. Such components include saturated hydrocarbons such as heptane, hexane, heptane, octane, nonane, cyclobutane, cyclopentane, cyclohexane, cyclohexane, 1-butene, 2-butene, 2-methylpropene, 1-pentene, etc. Unsaturated hydrocarbons such as 2-pentene, 1-butin, 2-butin, pentin, cyclopropene, cyclobutene, cyclopentene, cyclohexane, methanol, ethanol, normal propyl alcohol, isopropyl alcohol, normal butyl alcohol, isobutyl alcohol, sec- Alcohols such as butyl alcohol and tert-butyl alcohol, ethers such as dimethyl ether, ethyl methyl ether, diethyl ether, diisopropyl ether, methyl-tert-butyl ether and tetrafluoroethanol, acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone and methyl. Ketones such as isobutyl ketone, cyclopentanone, cyclohexanone, esters such as methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, methyl butyrate, ethyl butyrate, γ-butyrolactone, monomethylamine, dimethylamine , Amines such as trimethylamine, dichloromethane, 1,1-dichloroethane, 1,2-dichloroethane, 1,1,2-trichloroethane, 1,1,1,2-tetrachloroethane, 1,1,2,2-tetrachloroethane , Pentachloroethane, 1,1-dichloroethylene, cis-1,2-dichloroethylene, trans-1,2-dichloroethylene, trichlorethylene, tetrachloroethylene, 1,2-dichloropropane and other chlorocarbons, 1,1,1,3 3-Pentafluorobutane, 1,1,1,2,2,3,4,5,5-decafluoropentane, 1,1,2,2,3,3,4-heptafluorocyclopentane, 1 , 1,1,2,2,3,3,4,4-nonafluorohexane, 1,1,1,2,2,3,4,4,5,5,6,6-tridecafluoro Hexane, HFCs (hydrofluorocarbons) such as 1,1,1,2,2,3,3,4,5,5,6,6-tridecafluorooctane, decafluorobutane, dodecafluoropentane, tetra PFCs (perfluorocarbons) such as decafluorohexane, hexadecafluoroheptane, octadecafluorooctane, dichloropentaflu HCFCs (hydrochlorofluorocarbons) such as oropropane, 1,1-dichloro-1-fluoroethane, 1-chloro-1,1-difluoroethane, 2,2-dichloro-1,1,1-trifluoroethane, etc. However, it is not limited to these. Further, these components may be contained alone or in plurality.

When the cleaning composition contains components other than N-methyl-2-pyrrolidinone and N, N-dimethylformamide, the content ratio thereof is preferably 20% by mass or less, more preferably 5% by mass or less, 2 It is more preferably mass% or less. The components other than N-methyl-2-pyrrolidinone and N, N-dimethylformamide contained in the cleaning composition may be components that do not exert a cleaning effect among the above. Further, if the cleaning composition contains water, the water may adhere to the surface of the mask, causing stains or reducing the cleaning power of the solvent composition. Therefore, the content of water in the cleaning composition The amount is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 1% by mass or less. It is particularly preferred that the cleaning composition does not contain water.

The time for performing the cleaning step depends on the size of the mask, the type and amount of the attached organic matter, and the like, but may be, for example, 5 to 15 minutes. The temperature of the cleaning composition in the cleaning step may be room temperature without temperature control, preferably 10 to 40 ° C, more preferably 20 to 30 ° C. As described above, by cleaning in the above temperature range using a cleaning composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide, the cleaning property is excellent and the cleaning performance is excellent. The mask will not be deformed or distorted by the heat of.

Further, in the cleaning step, one type or two or more types of organic substances adhering to the surfaces of various masks can be sufficiently removed only by the above-mentioned cleaning composition. Therefore, as a result of not requiring a cleaning tank having a different type of cleaning liquid, the cleaning process becomes very simple.

The cleaning composition can be reused by distilling the used cleaning liquid composition. Even when the cleaning composition contains components other than N-methyl-2-pyrrolidinone and N, N-dimethylformamide, the used cleaning solution composition is distilled and the composition of the recovered solution is adjusted. Can be used.

In the rinsing step of the washing method of the present embodiment, the mask washed with the washing composition is rinsed with the rinsing composition. As used herein, rinsing means removing the cleaning composition adhering to the mask washed with the cleaning composition.

Examples of the method of rinsing the mask after washing include a method of immersing the mask after washing in the rinsing composition, a method of pouring the rinsing composition over the mask after washing, and the like. By either method, the cleaning composition adhering to the mask surface after cleaning can be easily removed, and the mask surface can be rinsed extremely cleanly. The time for performing the rinsing step depends on the size of the mask and the like, but may be, for example, 5 to 15 minutes. The temperature of the rinsing composition in the rinsing step may be room temperature without temperature control, preferably 10 to 40 ° C, more preferably 20 to 30 ° C. As described above, since the rinsing can be performed at a relatively low temperature, the mask is not deformed or distorted due to heat.

The rinse composition contains, as an active ingredient, at least one of hydrofluoroethers selected from HFE-347pc-f, HFE-254pc, HFE-356pcf and HFE-449mec-f. HFE-347pc-f, HFE-254pc, HFE-356pcf and HFE-449mec-f all have a low boiling point of 74 ° C. or lower, are excellent in drying property, and easily evaporate even at room temperature. Further, even if it is boiled to become steam, it is unlikely to adversely affect parts that are easily affected by heat such as resin parts. As the rinse composition, one kind of the above hydrofluoroether may be used alone, or two or more kinds thereof may be used in combination.

HFE-347pc-f has a zero ozone depletion potential and a small global warming potential. HFE-347pc-f has a boiling point of about 56 ° C. HFE-347pc-f is a method of reacting 2,2,2-trifluoroethanol with tetrafluoroethylene in the presence of, for example, an aprotic polar solvent and a catalyst (alkali metal alkoxide or alkali metal hydroxide). (See International Publication No. 2004/108644).
Examples of commercially available products of HFE-347pc-f include "Asahiclean (registered trademark) AE-3000" (manufactured by Asahi Glass Co., Ltd.).

HFE-254pc has a zero ozone depletion potential and a small global warming potential. The boiling point of HFE-254pc is 37 ° C. HFE-254pc can be produced, for example, by adding tetrafluoroethylene to methanol in the presence of a strong alkali (eg, potassium hydroxide).

HFE-356pcf has a zero ozone depletion potential and a small global warming potential. The boiling point of HFE-356pcf is 74 ° C. HFE-356pcf can be produced, for example, by adding chlorodifluoromethane (HCFC-22) to tetrafluoropropanol (TFPO) in the presence of a strong alkali (for example, potassium hydroxide).

HFE-449mec-f has a zero ozone depletion potential and a small global warming potential. The boiling point of HFE-449mec-f is 73 ° C. HFE-449mec-f is a method of reacting 2,2,2-trifluoroethanol with hexafluoropropene in the presence of, for example, an aprotic polar solvent and a catalyst (alkali metal alkoxide or alkali metal hydroxide). (Refer to JP-A-9-263559).

N-Methyl-2-pyrrolidinone and N, N-dimethylformamide in the cleaning composition have excellent solubility in any of the hydrofluoroethers in the rinse composition. Therefore, the cleaning composition is very easily removed by the rinsing composition. Further, the hydrofluoroether is not decomposed by any of N-methyl-2-pyrrolidinone and N, N-dimethylformamide contained in the cleaning composition. Therefore, fluorine ions do not remain on the mask surface after rinsing, and the mask can be washed extremely cleanly.

Here, the reason why the hydrofluoroether used in the rinse composition is not decomposed by N-methyl-2-pyrrolidinone and N, N-dimethylformamide contained in the washing composition is presumed as follows.

For example, hydrofluoroethers having a _{CF 3} − group with strong electron attraction, such as methyl-perfluoro-n-butyl ether (C ₄ F ₉ OCH ₃ , HFE-449 sl), are bonded to the _{CF 3 − group.} There is an electron deficiency in carbon. When an _{easily desorbed atom such as a halogen atom or an atomic group is bonded to the carbon to which the CF 3} -group is bonded, it is subjected to a nucleophilic attack by N-methyl-2-pyrrolidinone or N, N-dimethylformamide. It becomes easy to disassemble. In contrast, hydrofluoroether rinse composition used in the present embodiment, CF 3 _- or not have a group, or CF 3 _- have a group CF 3 _- is a leaving the carbon bonded Atoms or groups that are easily separated are not bonded. Therefore, the charge bias in the molecule is less likely to occur, and the nucleophilic attack from N-methyl-2-pyrrolidinone or N, N-dimethylformamide is less likely to occur.

The rinse composition used in the cleaning method of the present embodiment preferably contains HFE-347pc-f from the viewpoints that the cleaning composition can be sufficiently removed and the drying property is excellent.

The content ratio of the hydrofluoroether in the rinsing composition used in the washing method of the present embodiment is preferably 80 to 100% by mass, preferably 95 to 100% by mass, from the viewpoint of sufficiently rinsing the mask. More preferably, it is more preferably 98 to 100% by mass. When the rinsing composition contains two or more of the above hydrofluoroethers, the total content ratio thereof is preferably in the above-mentioned preferable range in that the mask can be sufficiently rinsed.

The rinse composition may contain components other than the above hydrofluoroether as long as the effects of the present invention are not impaired. Examples of the components other than the hydrofluoroether include, but are not limited to, the same components as those other than N-methyl-2-pyrrolidinone and N, N-dimethylformamide in the cleaning composition. Further, these components may be contained alone or in plurality.

When the rinse composition contains components other than the above hydrofluoroether, the content ratio of such components is preferably 20% by mass or less, more preferably 5% by mass or less, and preferably 2% by mass or less. More preferred.

As described above, if the cleaning composition contains water, the water may adhere to the surface of the mask and cause stains. When the rinse composition contains at least one alcohol selected from methyl alcohol, ethyl alcohol, normal propyl alcohol, and isopropyl alcohol, even if the cleaning composition contains water, the water is dissolved. It is preferable because it can be removed. When the rinse composition contains the above alcohol, the ratio of the alcohol content in the rinse composition is preferably 10% by mass or less, more preferably 1 to 8% by mass, from the viewpoint of sufficiently removing water. , 2-5% by mass, more preferably.

In the drying step of the washing method of the present embodiment, the mask after rinsing is dried in the rinsing step. As a drying method, a method of drying the mask after rinsing by natural drying, a method of drying by air blowing, a method of drying by decompression, or the like can be used. Among them, the method of drying under reduced pressure is preferable from the viewpoint that the mask can be dried more efficiently.

In the method of drying by air blowing, for example, it can be dried by blowing dry air at preferably 10 to 40 ° C, more preferably 20 to 30 ° C. As described above, since the mask can be dried at a relatively low temperature, the mask is not deformed or distorted due to heat.

When the mask is dried by depressurization, it takes time to depressurize, so a smaller degree of decompression is preferable. However, if the amount of the rinse composition adhered to the mask is small, it can be dried in the process of reducing the pressure. Therefore, it can be appropriately set according to the size of the mask and the amount of the rinse composition adhered to the mask. It is preferable to set the vapor pressure at ° C. or higher and 101.3 kPa or lower. For example, when the rinse composition is composed of HFE-347pc-f, it is preferable to reduce the pressure to a pressure of 25 to 101.3 kPa in the drying step.

According to the cleaning method of the embodiment described above, by using a specific hydrofluoroether as the rinsing composition, N-methyl-2-pyrrolidinone and N, N-dimethyl in the cleaning composition adhered to the mask during cleaning Neither of the formamides decomposes the hydrofluoroethers and does not generate fluorine ions. Therefore, the mask can be washed extremely cleanly. The cleaning method of the present embodiment is useful as a mask cleaning method when manufacturing an organic EL element by a vacuum vapor deposition method, and preferably a low molecular weight EL element is used in a vacuum vapor deposition step during manufacturing.

Next, experimental examples and examples will be described. The present invention is not limited to these experimental examples and examples.

(Experimental Example 1)
In this experimental example, the degradability of the rinse composition by NMP and DMF when heated for a predetermined time was investigated. A sample solution was prepared by adding 5% by mass of NMP or DMF to HFE-347pc-f (manufactured by Asahi Glass Co., Ltd., AE-3000) and 5% by mass of NMP or DMF to HFE-449sl (manufactured by 3M, Novec7100). .. Each sample solution was allowed to stand in a constant temperature bath at 55 ° C. for 3 days. The fluorine ion concentration in each solvent sample solution after standing was measured by a fluorine ion meter (manufactured by Toa DKK, IM-55G, fluorine ion electrode: manufactured by Toa DKK, F-2021). The detection limit of the fluorine ion concentration was 0.5 ppm. The results are shown in Table 1.

(Experimental Example 2)
In this experimental example, as an accelerated test, the degradability of the rinse composition by NMP when a sample solution containing HFE-347pc-f or HFE-449s and NMP was heated under reflux was investigated. To the same HFE-347pc-f (manufactured by Asahi Glass Co., Ltd., AE-3000), 250 g of a sample solution containing 5% by mass of NMP was placed in a flask and heated to a boiling state with a heater for 4 hours. Refluxed. Then, 175 g of the distillate was collected in 80 minutes, and the pH, fluorine ion concentration, and acid content of the remaining pot residue were measured. The results are shown in Table 2.

Further, 250 g of a sample solution prepared by adding 5% by mass of NMP to the same HFE-449sl (Novec7100 manufactured by 3M Ltd.) was placed in a flask, heated by a heater to boil, and refluxed for 4 hours. Then, 175 g of the distillate was collected in 80 minutes, and the pH, fluorine ion concentration, and acid content of the remaining pot residue were measured. The pH is measured with a pH meter (Toa DKK, HM-25R, electrode: Toa DKK, GST-5741C), and the fluorine ion concentration is measured with a fluorine ion meter (Toa DKK, IM-55G, Fluorine ion electrode: F-2021) manufactured by DKK-TOA CORPORATION, and the acid content was measured by titration using phenolphthaline as an indicator. The detection limit was 0.5 ppm for both the fluorine ion concentration and the acid content. The results are shown in Table 2.

From Tables 1 and 2, HFE-347pc-f in the rinse composition is not decomposed by NMP or DMF and does not generate fluorine ions even when heated for 3 days or heated and refluxed for 80 minutes, whereas HFE is not generated. It can be seen that -449sl was decomposed by NMP or DMF to generate fluorine ions.

(Example)
The detergency of the metal mask when HFE-347pc-f was used as the rinsing composition was investigated. A metal (SUS) piece to which a low-molecular-weight organic EL material is attached is immersed in NMP at room temperature (25 ° C.) for 1 minute. Then, the metal piece is rinsed and pulled up by immersing it in HFE-347pc-f (manufactured by Asahi Glass Co., Ltd., AE-3000) at room temperature (25 ° C.) for 1 minute. This metal piece is naturally dried and then immersed in pure water, and the extracted fluorine ion concentration is measured by a fluorine ion meter (IM-55G manufactured by DKK-TOA Corporation, fluorine ion electrode: F-2021 manufactured by DKK-TOA Corporation). To do. The detection limit of the fluorine ion concentration is 0.5 ppm. The results are shown in Table 3 as "detection" when fluorine ions are detected and "non-detection" when they are not detected.

(Comparison example)
The detergency of the metal mask when HFE-449sl was used as the rinsing composition was investigated. A metal (SUS) piece to which a low-molecular-weight organic EL material is attached is immersed in NMP at room temperature (25 ° C.) for 1 minute, and then immersed in HFE-449sl (manufactured by 3M Ltd., Novec7100) at room temperature (25 ° C.) for 1 minute. Rinse and pull up. After this metal piece is air-dried, it is immersed in pure water and the presence or absence of extracted fluorine ions is examined. The results are shown in Table 3.

From Table 3, it can be seen that the mask can be washed cleanly by using HFE-347pc-f as the rinsing composition. On the other hand, when HFE-449sl is used, it can be seen that fluorine ions are attached to the mask surface and the mask cannot be washed cleanly.

1 ... Glass substrate, 11 ... Transparent electrode, 20 ... Mask, 20h ... Opening, 21 ... Mask frame, 24 ... Holding stand, 30 ... Source.

Claims (9)

A method of cleaning masks for vacuum deposition,
The mask was washed with a washing composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide.
A washing method comprising rinsing the mask after washing with a rinsing composition containing a hydrofluoroether represented by _{CF 3} CH _2- O-CF ₂ CHF _2. The washing method according to claim 1, wherein the ratio of the content of the hydrofluoroether in the rinse composition is 80% by mass or more and 100% by mass or less. The cleaning method according to claim 1 or 2, wherein the cleaning composition contains N-methyl-2-pyrrolidinone. The cleaning method according to any one of claims 1 to 3 , wherein the mask is washed and rinsed at 10 ° C. or higher and 40 ° C. or lower. The cleaning method according to any one of claims 1 to 4 , wherein the mask is washed and rinsed at 20 ° C. or higher and 30 ° C. or lower. The cleaning method according to any one of claims 1 to 5 , wherein the vacuum vapor deposition is performed in the production of a low molecular weight organic EL device. The cleaning method according to any one of claims 1 to 6 , wherein the mask is dried after rinsing with the rinsing composition. A rinsing composition for rinsing a mask for vacuum deposition washed with a cleaning composition containing at least one selected from N-methyl-2-pyrrolidinone and N, N-dimethylformamide.
CF ₃ CH _2- O-CF ₂ A rinse composition comprising a hydrofluoroether represented by CHF _2. The rinse composition according to claim 8 , wherein the ratio of the content of the hydrofluoroether in the rinse composition is 80% by mass or more and 100% by mass or less.

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