JP2002192090A - Cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method by which dried stains do not remain in the subject to be cleaned. SOLUTION: This cleaning method comprises a step to clean the subject to be cleaned with a cleaning liquid, a step to rinse the cleaned subject with water, a step to finish rinsing the eater-rinsed subject with a rinse-finishing agent consisting of a poly basic alcohol capable of dissolving an inorganic compound, a step to subject the rinse-finished subject to solvent displacement with a volatile solvent for displacement having the compatibility with the rinse- finishing agent and a step to dry the solvent-displaced subject.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method, and more particularly, to a method for cleaning semiconductors, precision parts such as color filters for liquid crystals, optical lenses, etc., which require high surface cleanliness.

[0002]

2. Description of the Related Art Conventionally, in fields where precise drying is required, such as color filters for semiconductors and liquid crystals, after washing and rinsing with pure water, immersion in a hydrophilic solvent such as alcohol or exposure to steam is required. A method of draining and drying is performed.

At present, isopropyl alcohol (IPA) is mainly used as such a hydrophilic solvent.
That is, after the object to be cleaned is immersed in IPA and drained, hot air drying, lamp drying, reduced pressure drying, IPA steam drying, steam drying using a halogenated hydrocarbon, and the like are performed.

[0004] However, although a hydrophilic solvent such as IPA is excellent in drainage performance, since it has a large latent heat of vaporization and heat of vaporization compared to the previously used fluorocarbon, it takes more heat from the parts during drying, Cool the parts,
There is a problem that organic substances in the air are likely to be re-adsorbed, and moreover, dry spots become more noticeable due to moisture absorption.

[0005] Steam drying using a highly polar solvent such as IPA or a halogenated hydrocarbon tends to cause whitening and cracking of plastic parts and resin coatings referred to as solvent attack.

Further, in the IPA vapor drying, the introduced water has a ratio of water: IPA of 12.6: 87.4.
At this time, an azeotropic mixture is formed, having an azeotropic point of 80.3 ° C. As a result, the water concentration in the steam tank also tends to increase. This leads to the generation of watermarks and particles, which causes the drying property to decrease.

Further, as described above, since IPA takes in water, the reuse rate of IPA naturally decreases.

[0008] The water concentration in IPA is controlled by liquid exchange according to the lifetime of the liquid and the number of treatments, and the specific resistance of the liquid, but the water content that can exert the effect as IPA is small. . The development of an IPA playback device and the like is also being studied, but a large investment is required.

As an alternative to the IPA, it has been proposed to use a siloxane having excellent volatility. For example, JP-A-2000-38598 discloses a drying method using a mixed solution of a low-molecular siloxane and a hydrophilic solvent.

However, there is a problem that even when this method is used, dry spots appearing on the surface of the object to be cleaned cannot be completely eliminated.

[0011]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. That is, an object of the present invention is to provide a cleaning method in which dry spots do not remain on a cleaning target.

[0012]

According to the present invention, there is provided a cleaning method comprising the steps of: cleaning a body to be cleaned with a cleaning solution; rinsing the body to be cleaned with water; and dissolving the body to be cleaned in an inorganic compound. A step of finishing rinsing with a finishing rinse made of a polyhydric alcohol provided, a step of solvent-exchanging the object to be cleaned with a volatile substitution solvent having compatibility with the finishing rinse, Drying step.

In the above-mentioned washing method, the polyhydric alcohol having a solubility in the inorganic compound is a polyhydric alcohol having a solubility in an inorganic compound such as sodium chloride, zinc chloride, potassium carbonate, potassium hydroxide, and calcium hydroxide. Refers to a hydric alcohol. Examples include ethylene glycol and diethylene glycol.

When ethylene glycol is used as the finishing rinse, there is an advantage that it can be repeatedly used by passing it through an ion exchange resin.

In the above method, the step of rinsing with the water;
Between the final rinsing step and the final rinsing step, one or more preliminary rinsing steps of preliminary rinsing with a mixture of a polyhydric alcohol having solubility for the inorganic compound and water may be further provided. In this case, the mixing ratio of the polyhydric alcohol having solubility to the inorganic compound and water is, for example, a mixing ratio of polyhydric alcohol having water to the inorganic compound: water = 60: 30 to 80:20. Between is preferred. Further, two or more preliminary rinsing steps may be provided by changing the mixing ratio.

In the above method, the substitution solvent may be a hydrophilic solvent, a mixture of a volatile silicone composition and a hydrophilic solvent, a fluorinated solvent, or a mixture of a fluorinated solvent and a hydrophilic solvent. .

In the above method, the hydrophilic solvent is required to be compatible with the finish rinsing agent and to be volatile.

The hydrophilic solvent includes, for example, at least one selected from aliphatic alcohols, ketones, esters and glycols having a molecular weight of 130 or less.

Specific examples of the hydrophilic solvent include methanol, ethanol, 1-propanol (n-propanol), 2-propanol (isopropanol),
-Butanol, 2-butanol, isobutanol, te
rt-butanol, tert-pentanol, 3-methyl-2-butanol, cyclohexanol, acetone,
Methyl ethyl ketone (MEK), ethyl acetate, propyl acetate, butyl acetate, pentyl acetate, methyl propionate, ethyl propionate, butyl propionate, 2-pentanone, 2-methoxyethanol, 2-ethoxyethanol, 2- (methoxymethoxy) ethanol , 2-isopropoxyethanol, 2-butoxyethanol, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, dipropylene glycol dimethyl ether, polypropylene glycol monomethyl ether, and the like. . These hydrophilic solvents can be used alone or in combination.

In the above-mentioned cleaning method, examples of the fluorine-based solvent include perfluorocarbon, hydrofluoroether, and trifluoroethanol.

In the above method, the volatile silicone composition includes a low molecular weight polyorganosiloxane having 1 to 6 SiO units.

Further, the low molecular weight polyorganosiloxane is

Embedded image (Wherein, R represents the same or different substituted or unsubstituted monovalent organic group, l represents an integer of 0 to 5) and a linear polyorganosiloxane represented by the general formula:

Embedded image (Wherein, R represents the same or different substituted or unsubstituted monovalent organic group, and m represents an integer of 3 to 7) at least one low molecular weight polyorganosiloxane selected from the group consisting of: And organosiloxanes.

Examples of the low molecular weight polyorganosiloxane include octamethyltrisiloxane (MDM) and decamethyltetrasiloxane (MD2).
M), dodecamethylpentasiloxane (MD3M), octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6) and the like.
Among them, D4, D5, D6, MD2 having a high boiling point
M and MD3M are preferred. These low molecular weight polyorganosiloxanes can be used alone or in combination.

As the low molecular weight polyorganosiloxane, D4 and D5 are preferred because good solvent substitution can be obtained with a small blending amount.
It is preferably 0% by weight. D4 and D5 are preferably used in combination with an aliphatic alcohol since a good effect is obtained.

The silicone composition further comprises:
Organic solvents, surfactants and / or stabilizers may be included.

When a polyorganosiloxane having a higher molecular weight than the low-molecular-weight polyorganosiloxane used in the present invention is used, the siloxane tends to remain and the cleanliness of the surface to be cleaned is impaired.

The substitution solvent used in the present invention shows good solvent substitution property by immersion. Furthermore, since it has degreasing properties, it is possible to remove light oil and particles. It is more preferable to use ultrasonic and mechanical stirring together.

The solvent substitution immersion tank with the substitution solvent according to the present invention comprises a single layer or a plurality of tanks. When it is composed of a plurality of tanks, the same or different mixed liquids may be used. In addition, it is preferable to adopt a cascade system so that the substitution solvent overflows in the direction opposite to the transport direction.

When a mixture of a low-molecular-weight polyorganosiloxane and a hydrophilic organic solvent is used as the substitution solvent, a draining method can be used.

In the cleaning method of the present invention, in addition to immersing the cleaning object in the replacement solvent, the cleaning solvent is sprayed on the cleaning object, or the cleaning object is exposed to a gas in which the replacement solvent is vaporized. It is possible to solvent-replace the finishing rinse present on the surface of the cleaning body with the replacement solvent.

Further, by exposing to a vaporized gas in a nitrogen atmosphere, oxygen in the atmosphere can be shut off, the generation of watermarks can be further prevented, and the safety can be increased.

According to the cleaning method of the present invention, the surface of the object to be cleaned can be dried by quickly and uniformly drying after the solvent replacement by the above method.

In the cleaning method of the present invention, it is considered that the inorganic substance which is a source of dry spots is removed by the action of the finish rinsing agent used in the finish rinsing step. That is, if the components such as the cleaning liquid used in the preceding cleaning step and the ions contained in the water remain, salts such as NaCl and KCl are generated in the drying step, and this is considered to cause dry spots.

In the cleaning method of the present invention, various cations and chlorine ions are removed by the action of the finishing rinse made of a polyhydric alcohol having a solubility in inorganic compounds such as ethylene glycol used in the finishing rinsing step. It is considered that various cations and chlorine ions do not remain on the surface of the object to be processed, and therefore, no drying spots are formed on the surface of the object after drying.

Further, in the present invention, the solvent is replaced after the finish rinsing, and the finish rinsing agent is replaced with a volatile solvent, followed by drying.

The cleaning method of the present invention is applicable to various objects to be cleaned, and the material of the object to be cleaned is not particularly limited, and examples thereof include metals, metalloids, ceramics, and plastic materials. For example, metals, metalloids are iron, aluminum, silicon, copper, stainless steel, etc., ceramics are silicon nitride, silicon carbide, aluminum oxide, glass, porcelain, etc., and plastics are polyamide, polyimide, epoxy, polyolefin, polyester. , Acrylic resin and the like, and a composite material thereof may be used. Specific examples include electronic components such as printed circuit boards and mounting components, objects to be cleaned, semiconductor components, metal components, surface treatment components, precision equipment components, objects to be cleaned, glass components, ceramic components, plastic components, and the like.

[0037]

Embodiments of the present invention will be described below.

FIG. 1 is a flowchart showing the operation of each step of the cleaning method of the present invention. Tables 1 to 4 are tables summarizing the processing conditions of each step in FIG. 1 for each step.

[0039]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

In each of the steps 1 to 11, each step was performed while oscillating ultrasonic waves in the processing tank and mechanically oscillating the processing liquid to promote operations such as washing and rinsing.

As the test sample, a glass lens type test sample that conforms to the standard for a single-lens reflex lens is used.
With respect to this test sample, the glass lens was cleaned in accordance with the conditions described in Table 1 and the flow of FIG.

That is, a glass lens (material: glass for lens, thickness: 5 mm, diameter:
75 mm). For this test sample, Na
After alkali cleaning using OH (step 1), the substrate was rinsed with city water (step 2).

After this, a surfactant (Sunwash.
The test sample was immersed in an aqueous solution in which (trade name) / (Kao Co., Ltd.) was dissolved for 45 seconds (step 3), and transferred to a washing tank filled with a solution having the same composition, and subjected to the same washing ( Step 4).

After washing with the aqueous surfactant solution, rinsing with city water is performed twice by changing the treatment tank (steps 5 to 6).
Next, rinsing was performed using pure water (step 7).

Using this glass lens as a test sample, using each of the finishing rinses shown in Examples 1 to 4 and Comparative Examples 1 to 20 in Table 1, in the finishing rinsing step (Step 8), The pure water adhering to the object to be cleaned is removed by dissolution or elimination / sedimentation by immersion and rocking at 30 ° C. for 45 seconds, and then solvent replacement is performed twice with a replacement solvent (step 9). To 10), and then dried (step 11).

In the drying step of step 11, the lens is pulled up from the immersion tank filled with the replacement solvent, held vertically, and after the liquid has run out, the liquid pool at the end is removed. IPA, low molecular weight polysiloxane composition,
Using trifluoroethanol), steam drying was performed for 45 seconds while heating.

In the method of evaluating the dried test sample surface, the surface of the treated glass lens type test sample was exposed to light using a halogen lamp as a light source, and the condition of the lens surface was visually evaluated. Table 5 shows the substances used and the evaluation results.

[0048]

[Table 5]

(Examples 1 to 4) In Example 1, in the finishing rinsing step of Step 8, ethylene glycol was used as a finishing rinsing agent. In the subsequent solvent replacement process in steps 9 to 10, solvent replacement was performed using IPA (isopropyl alcohol) as a replacement solvent.

In Example 2, diethylene glycol was used as the finishing rinse. In the subsequent solvent replacement step, liquid removal was performed using IPA (isopropyl alcohol) as a replacement solvent.

In Example 3, ethylene glycol was used as the finishing rinse. In the subsequent solvent replacement, a low molecular weight polysiloxane composition was used as a replacement solvent. This substitution solvent is a mixture of 10 parts by weight of decamethylcyclopentasiloxane (D5) as a low molecular weight polysiloxane and 90 parts by weight of secondary butanol as a hydrophilic organic solvent. In the drying step after the solvent replacement, 8
It was dried with hot air at 0 ° C.

In Example 4, diethylene glycol was used as the finishing rinse. In the subsequent solvent replacement step, solvent replacement was performed using trifluoroethanol as a replacement solvent. In the drying step after solvent replacement, 7
Dry at 4 ° C. in a trifluoroethanol vapor atmosphere.

With respect to Examples 1 to 4, no dry spot was observed on any of the test samples. FIG. 1 shows a photograph of the lens cleaned by the cleaning method described in Example 1. As shown in FIG. 1, no dry spots were observed on the lens surface cleaned by the method of Example 1.

(Comparative Examples 1 to 20) In Comparative Examples 1 to 20,
In the finishing rinsing step of step 8, the substances listed in Table 2 were used as finishing rinsing agents. Subsequent steps 9-1
In the solvent replacement step of 0, solvent replacement was performed using IPA (isopropyl alcohol) as a replacement solvent.

In these Comparative Examples 1 to 20, solvent substitution was performed using IPA as a substitution solvent, but in each case, white spots appeared on the test sample. FIG. 2 shows a photograph of the lens cleaned by the cleaning method shown in Comparative Example 1. As shown in FIG. 2, dry stains appeared on the entire surface of the lens cleaned by the method of Comparative Example 1.

As described above, according to the results of Examples 1 to 4 and Comparative Examples 1 to 20, according to the cleaning method of the present invention, the object to be cleaned can be cleaned without causing dry spots.

In the cleaning method of the present invention, it is considered that the inorganic substance which is a source of dry spots is removed by the action of the finish rinsing agent used in the finish rinsing step. That is, if alkali such as NaOH used in the preceding alkali washing and chlorine contained in water remain, NaCl or KC
It is considered that an inorganic salt such as 1 is produced, which causes dry spots.

In the cleaning method of the present invention, alkali ions and chlorine ions are removed by the action of the finishing rinse agent comprising a low-viscosity polyhydric alcohol such as ethylene glycol used in the finishing rinsing step. It is considered that no ions or chlorine ions remain, so that no dry spots are formed on the surface of the object after drying.

[0059]

According to the cleaning method of the present invention, the inorganics which are the source of dry spots are removed in the step of finish rinsing with a finish rinsing agent having solubility for inorganic compounds. Dry spots can be eliminated.
Further, since the solvent is replaced after the final rinsing step and then the drying is performed, the drying can be performed quickly.

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps of a cleaning method of the present invention.

FIG. 2 is a photograph of a lens cleaned by the cleaning method of Example 1 of the present invention.

FIG. 3 is a photograph of a lens cleaned by the method of Comparative Example 1.

Continued on the front page F term (reference) 3B201 AA03 AB01 AB38 BB05 BB82 BB93 BB94 BB95 CA01 CB15 CC01 CC11 CC21 4D056 EA01 EA03 EA08

Claims (7)

[Claims] 1. A step of washing an object to be cleaned with a cleaning liquid; a step of rinsing the object to be cleaned with water; and a step of rinsing the object to be washed with a finishing rinse made of a polyhydric alcohol having solubility for an inorganic compound. A cleaning method comprising: a step of performing a final rinsing; a step of solvent-exchanging the object to be cleaned with a volatile substitution solvent having compatibility with the final rinsing agent; and a step of drying the object to be cleaned. . 2. The cleaning method according to claim 1, wherein the step of rinsing with water and the step of finishing rinsing include:
A cleaning method, further comprising at least one preliminary rinsing step of preliminary rinsing with a mixture of a polyhydric alcohol having water solubility with respect to the inorganic compound and water. 3. The cleaning method according to claim 1, wherein the volatile solvent is a hydrophilic solvent, a mixture of a volatile silicone composition and a hydrophilic solvent, a fluorinated solvent, or a fluorinated solvent. A cleaning method comprising a mixture of a solvent and a hydrophilic solvent. 4. The cleaning method according to claim 1, wherein the low-viscosity polyhydric alcohol is ethylene glycol or diethylene glycol. 5. The cleaning method according to claim 1, wherein the hydrophilic solvent is selected from aliphatic alcohols, ketones, esters, and glycols having a molecular weight of 130 or less. And the volatile silicone composition is a low molecular weight polyorganosiloxane having 1 to 6 SiO units, and the fluorine-based solvent is perfluorocarbon, hydrofluoroether, or trifluoroethanol. A cleaning method characterized by the above-mentioned. 6. The cleaning method according to claim 5, wherein
The low molecular weight polyorganosiloxane is represented by the following formula: (Wherein R represents the same or different substituted or unsubstituted monovalent organic group, and l represents an integer of 0 to 5), and a linear polyorganosiloxane represented by the general formula: (Wherein, R represents the same or different substituted or unsubstituted monovalent organic group, and m represents an integer of 3 to 7) at least one low molecular weight polyorganosiloxane selected from the group consisting of: A washing method, which is an organosiloxane. 7. The cleaning method according to claim 6, wherein the low molecular weight polyorganosiloxane is octamethyltrisiloxane, decamethyltetrasiloxane, dodecamethylpentasiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane. A cleaning method comprising at least one selected from siloxane and dodecamethylcyclohexasiloxane.