JPH07299426A - Fine cleaning method and cleaning device - Google Patents

Abstract

PURPOSE:To provide a cleaning method and device capable of cleaning regardless of the shape and material of a material to be cleaned, cleaning any part at a high yield, improving heat efficiency to reduce the consumption of heat and securing the quality of fine cleaning and excellent in work efficiency. CONSTITUTION:This cleaning device is constituted of a process for dipping the material 3 to be cleaned into a cleaning solution 1 essentially consisting of an organosilicon compound and a process for pulling up the material 3 dipped into the cleaning solution 1 from the boundary of the cleaning solution 1 at <=70mm/sec pulling up speed. As the organosilicon compound, a low molecular weight polydiorganosiloxane being at least one kind selected from a linear polydiorganosiloxane and a cyclic polydiorganosiloxane is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the field of precision cleaning technology, and more particularly to a precision cleaning method and a cleaning device for optical lenses used in cameras, microscopes, lasers and the like, and semiconductor parts such as wafers.

[0002]

2. Description of the Related Art In the precision field, a precision cleaning process is an indispensable process, and is in the most important position along with the processing process. Conventionally, in the cleaning process in the precision field, a halogen-based solvent such as CFC or trichloroethane, which has high safety for human body, is easy to reproduce the purity, and has good workability, has been used. However, in recent years, the halogen-based solvent has been prohibited or reduced in use worldwide due to the danger of ozone layer depletion.

For this reason, recently, a cleaning method substituting for a halogen-based solvent is being developed. However, the development of a cleaning method in line with the rapid superprecision of the industry requires the cleaning degree and the cost of workability. It is tough and extremely difficult. Among them, a system using pure water has been developed, and in Japanese Patent Laid-Open No. 1-210092, a precision cleaning in the preceding stage is performed on an object to be cleaned, followed by a final cleaning with pure water, and then a dry gas is used. In a cleaning method for removing water from the surface to be cleaned of a cleaning object, there is described a drying method of precision cleaning in which an object to be cleaned immersed in cleaning water of pure water is pulled up from the water surface into the gas at an extremely low speed. .

[0004]

In the conventional method described in the above publication, precision cleaning is possible by using water, which is the most common cleaning liquid, in the form of pure water. However, water has very unique properties in terms of physical and chemical properties as compared with other substances, and therefore its working efficiency is very poor in the precision cleaning field. In fact, in the above method, since the specific heat of water is high, a large amount of heat was required during heating and cooling during cleaning. Furthermore, since water has a high latent heat of vaporization, decontamination during evaporation causes reattachment of pollutants, which is likely to cause quality defects. Also,
Since the surface tension of water is very large, it is not possible to get in and out of the non-through holes such as small gaps and screw parts of the object to be cleaned, and it is impossible to drain liquid even for members with complicated shapes with severe unevenness,
In addition, the quality of the dirt was constantly brought out by picking up and adsorbing the dirt, and the effect could not be exhibited at all. Further, even if pure water is pure water, it has an attacking property against metal materials, and it is impossible to clean mirror-polished aluminum or magnesium alloy.

The inventions according to claims 1 to 4 have been made in view of the above-mentioned conventional problems, and can be cleaned regardless of the shape and material of the object to be cleaned, and any part can be cleaned with good yield, and further, thermal efficiency can be improved. It is an object of the present invention to provide a precision cleaning method and a cleaning device with improved work efficiency, which can reduce heat consumption and ensure the quality of precision cleaning. In particular, the invention according to claims 2 and 3 aims to provide a precision cleaning method having further improved cleaning ability in addition to the above objects.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is such that in performing precision cleaning,
The step of immersing the object to be cleaned in a cleaning liquid containing an organic silicon compound as a main component, and the object to be cleaned immersed in the cleaning liquid to 70 mm
and a step of pulling up from the cleaning liquid interface at a pulling rate of / s or less.

According to a second aspect of the present invention, in the precision cleaning method according to the first aspect, the linear polyorganosiloxane represented by the general formula 1 and the cyclic group represented by the general formula 2 are used as the organosilicon compound. At least one low molecular weight polyorganosiloxane selected from polyorganosiloxanes was used.

[0008]

[Chemical 1]

[0009]

[Chemical 2]

According to a third aspect of the present invention, in the precision cleaning method according to the second aspect, the cleaning liquid has a purity of 99.9 wt% or more.

The invention according to claim 4 is a tank for storing a cleaning liquid containing an organic silicon compound as a main component, a circulation device for performing microfiltration treatment while circulating the cleaning liquid, and supplying a clean liquid, and an object to be cleaned. A precision cleaning device equipped with a lifting mechanism for lifting the liquid from the liquid surface at a lifting speed of 70 mm / s or less, a drying assisting means for promoting the drying of the lifted object to be cleaned, and a control unit for controlling the cleaning device. Configured.

In other words, as a result of many studies on problems that could not be overcome by conventional water, a conceptual diagram is shown in FIG.
As described above, in the invention according to claims 1 to 3, a step of injecting a cleaning liquid 1 containing an organosilicon compound as a main component into a cleaning tank 2 and immersing an object to be cleaned 3 in the cleaning liquid 1, and the cleaning liquid 1 Provided is a precision cleaning method comprising a pulling-up step of pulling the object to be cleaned 3 dipped in the substrate at a low speed from the cleaning liquid interface, and the pulling-up speed of the pulling step is 70 mm / s or less.

[0013]

The present inventors have studied various materials to solve the conventional problems, and as a result, they have been mainly used as a mold release agent, cosmetics, lubricants, defoaming agents, etc. in recent years and also used as a cleaning agent in recent years. A cleaning method suitable for precision cleaning was found using the known organosilicon compound. Organosilicon compounds are safe for the human body and can be purified with high purity as they are used in cosmetics.
Furthermore, it is also suitable for precision cleaning as compared with water in terms of its physical properties and other properties. Thus, even an organosilicon compound, which has properties considerably superior to water, cannot exert its ability depending on the method of use. Therefore, it is necessary to set the cleaning conditions according to the properties of the organosilicon compound, and as a result of the investigation, the precision cleaning method of the present invention was achieved.

The point that the organosilicon compound is suitable for precision cleaning is that, firstly, the organosilicon compound has a specific heat of 0.3.
~ 0.5cal / g ℃, 1/2 to 1/3 compared to water
And very low. Therefore, the amount of heat applied for heating can be suppressed to half or less. Second, the surface tension of the organosilicon compound is about 20 dyne / cm, and the surface tension of water is 72.75 dy.
Very low compared to ne / cm. Therefore, it is possible to easily get in and out of a small gap that cannot be put in and out with water and a non-through hole such as a screw portion, and it is possible to cope with a complicated shape having a large unevenness without any problem. Thirdly, the latent heat of vaporization of organosilicon compounds is 25 to 50 cal / g, and that of water is 539 cal / g.
It is about 1/10 to 1/20 compared with g. Usually, a large amount of heat of evaporation is removed from the member after the water is evaporated, and the surface temperature is instantly lowered, and the water vapor existing in the surrounding atmosphere is condensed there. Although this condensation causes the final quality of the object to be cleaned to deteriorate, the organosilicon compound belongs to the one with the lowest latent heat of vaporization among many materials,
Since there is almost no decrease in the surface temperature of the member after the actual evaporation, there is no problem of dew condensation of water vapor on the surface, and no accompanying deterioration in final quality is observed. Further, since the latent heat of vaporization is low, it is easy to evaporate, and the distillation regeneration is also easy.

As described above, as a result of the examination of setting the cleaning conditions in accordance with the property of the organosilicon compound, which has properties considerably superior to those of water, the present cleaning method was obtained. The operation will be described below. Usually, when an object to be cleaned that has been dipped in the cleaning liquid is pulled out from the cleaning liquid, the cleaning liquid remains on the surface in the form of spots or blocks, and dust adheres due to concentration in the drying process or stains due to the remaining liquid in the previous stage. That leads to quality deterioration as the actual cleaning residue. However, like the cleaning method of the present invention, by pulling the object to be cleaned at a low speed, by the balance of the cohesive force and viscosity of the cleaning liquid and the surface tension, the liquid is drained without remaining in a spot or block on the surface of the object to be cleaned. It was confirmed to be done. further,
By the same action, the liquid is discharged from the gap between the objects to be cleaned and the non-through holes such as screw holes, and the liquid remains. As a result, there was no dust adhesion due to the concentration of the liquid or stains due to the remaining liquid in the previous stage, and it was possible to always obtain a uniform clean surface.

This operation will be described with reference to FIG. 2. In the process of immersing the object to be cleaned 3 in the cleaning liquid 1 and then lifting it from the cleaning liquid 1, the cleaning surface of the object to be cleaned 3 above the liquid surface 1a, that is, the cleaning liquid. 1 on the boundary surface between the cleaning object 1 and the surface of the cleaning object 3
The cleaning liquid 1 adheres in the form of a thin film due to the viscosity of, and rises with the object to be cleaned 3. However, naturally, on the other hand, since the cohesive force and surface tension of the cleaning liquid 1 itself act, a lifting height h of the cleaning liquid 1 is generated at the liquid surface 1a. If the speed of pulling up the object to be cleaned 3 is slower than the falling speed of the cleaning liquid 1 due to the cohesive force and the viscosity, a thin film of the cleaning liquid 1 is uniformly formed and draining is performed, so that a defect does not occur on the cleaning surface. Absent. However, if the pulling speed of the cleaning object 3 is faster than the falling speed of the cleaning liquid 1, as shown in FIG. 3, a uniform thin film of the cleaning liquid 1 is not formed on the surface of the lifted cleaning object 3,
The cleaning liquid 1 remains in the form of spots or blocks on the surface of the object to be cleaned 3, and stains 4 are generated due to the adhesion of dust and the remaining liquid in the previous stage.

The speed at which a clean surface can be obtained by this lifting method depends on the physical properties of the cleaning liquid, the object to be cleaned, and the like. The present inventors have conducted various studies using metal, resin, glass, ceramic, and elastomer for the object to be cleaned, and organic silicon compounds for the cleaning liquid, and as a result, if the pulling rate is 70 mm / s or less, It was confirmed that it is possible to obtain a clean surface with any material.
On the other hand, when the film was pulled up at a speed exceeding 70 mm / s, the film thickness on the surface of the object to be cleaned was not formed uniformly, and a stain-like residue was confirmed. Therefore, in this cleaning method, the pulling rate was set to 70 mm / s or less. Of course, it is desirable that the pulling speed is uniform, but it may be varied by shortening the cleaning process. In that case, if the speed is 70 mm / s or less only when the object to be cleaned is on the surface of the cleaning liquid, No problem. Further, the slower the pulling rate is, the less the amount of the cleaning liquid taken out is, and the running cost is lowered.

As the cleaning liquid containing an organosilicon compound as a main component used in the present invention, it is most desirable to use a low molecular weight polyorganosiloxane as a simple substance, but a mixture of a low molecular weight polyorganosiloxane and a hydrocarbon, or a low molecular weight polyorganosiloxane. Either a mixture of polyorganosiloxane and alcohol or a mixture of low molecular weight polyorganosiloxane and esters may be used, and particularly, an azeotropic composition is preferable.

The hydrocarbons used here include paraffinic, isoparaffinic, and naphthenic hydrocarbons having 6 to 12 carbon atoms, and the alcohols include alcohols having 2 to 10 carbon atoms and esters. Examples thereof include esters of carboxylic acids having 1 to 6 carbon atoms and alcohols having 1 to 4 carbon atoms.

Further, in order to obtain a clean surface for precision cleaning, the concentration of impurities in the cleaning liquid is preferably less than 0.1 wt%, and for ultra-precision cleaning, the concentration of impurities in the cleaning liquid is desired. It is preferably 0.01 wt% or less. When it is 0.1 wt% or more, the film thickness on the surface of the object to be cleaned is not formed uniformly, and stain-like residues are generated, which is unsuitable for the present cleaning method. Here, the impurities mean a component having a boiling point higher than that of the cleaning liquid component and a non-volatile component.

In the present cleaning method, ultrasonic waves and jets are used as physical means for cleaning in the cleaning tank when the cleaning target is immersed in the cleaning liquid, so that the clearances and screw holes of the cleaning target are not removed. It is also possible to impart an effect of further improving the permeability to the through holes. Further, since the organosilicon compound used in the cleaning method of the present invention has a small latent heat of vaporization as described above, it can be vaporized with a small amount of energy, and is dried by applying warm air when pulling it up by the method of the present invention. It is also possible to promote.

[0022]

First Embodiment A first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, as the cleaning liquid 1 in the dipping process, a cleaning tank 2 filled with octamethyltrisiloxane is dipped with an object to be cleaned 3 including an optical lens, and is slowly pulled up using a pulse motor (not shown). And washed. The octamethyltrisiloxane used as the cleaning liquid 1 had a purity of 99.99 wt% or less as a result of measurement by gas chromatography. The liquid temperature of the cleaning liquid 1 is 25 ° C. The optical lens used as the object to be cleaned 3 is processed for an ultra-precision measuring machine, and has a shape of φ7.0 mm, thickness of 1.5 mm,
With a concave shape with a radius of curvature of 25.3 mm and a plano-concave lens with one plane,
As the glass material, a lens with double-sided polished surface of SK11 was used. As shown in FIG. 4, the article to be cleaned 3 was attached to a toy 5 which supports the outer peripheral portion of the article to be cleaned 2 at two points and was cleaned. The pulling speed was four types of 5 mm / s, 10 mm / s, 15 mm / s, and 20 mm / s.

As a comparative example, the cleaning liquid 1 has an electric conductivity of 5 μS.
Pure water was used at 25 ° C. and four pulling-up methods were performed as in this example.

The cleaning was evaluated by visual evaluation of the optical lens after cleaning with reflected light and transmitted light under fluorescent light, and breath evaluation with visual evaluation by applying breath to the optical lens surface with reflected light under fluorescent light. , Magnesium fluoride (Mg
With coatings of F ₂₎ is performed in 3 Evaluation of coating evaluation for evaluating visually under a fluorescent lamp reflected light, which foreign matter was observed was determined that all defective. The number of evaluations is n = 20
I went there. The weight of the cleaning liquid carried out was measured when n = 20 using a lens toy with an optical lens.

The above results are shown in Table 1.

[0026]

[Table 1]

As shown in Table 1 above, no defects occurred at all in this embodiment. On the other hand, in the comparative example, all of the samples having a low pulling rate passed the visual evaluation only, but almost half of them were defective in the coating evaluation, which was clearly different from the present example. As shown in FIG. 5, the stains on the defective lens were mostly stains 6 in the vicinity of the supporting portion of the toy. This is because the pure water used in the comparative example has a large surface tension, so that a liquid pool is generated in the yatoy support part, and the concentration of dirt in that part, the adsorption of dirt in the air, etc. occur, resulting in a defect. It is a thing. On the contrary, when cleaning is performed by the method shown in the present embodiment, the cleaning liquid octamethyltrisiloxane has a small surface tension, and therefore, liquid pool does not occur in the yatoy support portion, so that the cleaning is completed. . Furthermore, in this example, it was confirmed that the amount of the cleaning liquid taken out was small, and that it could be considerably reduced by slowing the pulling rate. In addition, the pulling rate is 30 with the same experimental method.
n = 20 even at mm / s, 50 mm / s, 70 mm / s
It was also confirmed that there was no problem in the evaluation.

As described above, by using the cleaning method of this embodiment, it was confirmed that the optical lens for ultra-precision can be cleaned, and that it is very effective as compared with the conventional one. In other words, you can wash regardless of the shape and material of the object to be washed, you can wash any part with a good yield, further improve thermal efficiency to reduce heat consumption, and ensure the quality of precision cleaning and work efficiency .

Further, in addition to the cleaning method of this embodiment, a method of applying ultrasonic waves to the step of immersing the object to be cleaned was also performed. However, ultrasonic waves were stopped in the pulling up process in order to keep the liquid surface stationary. By applying ultrasonic waves, the cleaning liquid can easily penetrate into the fine gaps, and the dipping process time can be shortened. As for this method, the same effect can be obtained by using a physical force such as a jet flow or oscillation in addition to ultrasonic waves. Further, as an example of the cleaning liquid, an azeotropic cleaning liquid shown in Table 2 was used as the cleaning liquid, and the same evaluation as in Table 1 was carried out at the number of cleanings of n = 20. There was no occurrence.

[0030]

[Table 2]

[0031]

Example 2 In this example, in addition to the cleaning method of Example 1, the temperature of the cleaning liquid was raised to 40 ° C. for cleaning. The immersion time was 1 minute, and hexamethyldisiloxane, which is an organosilicon compound, was used as the cleaning liquid. The purity of hexamethyldisiloxane is 9 as measured by gas chromatography.
It was purified to 9.995 wt% or less. As a comparative example, cleaning was performed using pure water as in Example 1. Cleaning was performed in the same cleaning tank, but since the specific heat of hexamethyldisiloxane of the cleaning liquid used in this example was small, in this example, it was 40 ° C. in about half the time of the comparative example. I was able to warm to. Further, hexamethyldisiloxane was easily evaporated, and the drying time after washing was shortened by 5 times or more as compared with the comparative example. Furthermore, since this cleaning liquid has a low latent heat of vaporization, it was dried without condensation of moisture in the air when dried with cold air, but the product washed by the cleaning method using the pure water of the comparative example was condensed with cold air. Could not be dried.

Therefore, the present embodiment has the same effects as those of the first embodiment, the thermal efficiency is better than that of the comparative example, the drying time is shorter, and there is no dew condensation during the drying. . By applying this embodiment to the actual cleaning process, the utility cost can be reduced and the cleaning process time can be shortened.

Further, the aluminum alloy was cleaned by the cleaning method of the present example, and the attack test was conducted. The aluminum alloy has a plate shape of 50 × 50 × 2 mm, and the square surface is mirror finished. After washing, leave it for 1 hour,
When the surface was confirmed by a stereoscopic microscope with a magnification of 20 times, the aluminum alloy washed by this cleaning method did not show any attack on the clean surface, but in the comparative example, the aluminum surface was attacked and the mirror surface was clouded. Therefore, it was confirmed that the precision mirror surface aluminum material which could not be conventionally cleaned by the cleaning method of the present embodiment can also be cleaned.

Incidentally, in Example 1 and Example 2,
When an experiment was performed with the pulling speed of the object to be cleaned exceeding 70 mm / s, the cleaning liquid remained in the form of spots or blocks on the surface of the object to be cleaned, and dust adhesion due to concentration in the drying process and Spots and the like due to the remaining liquid have occurred.

[0035]

[Embodiment 3] This embodiment is an example of a cleaning machine using the cleaning method of the present invention and will be described with reference to FIG. (Structure) A main tank 24 that stores a cleaning liquid 11 containing an organic silicon compound as a main component, and is connected to an overflow drain pipe 12, a drain drain pipe 13, and a liquid supply pipe 14, respectively, and this main tank 24 and a closed pipe System connected, heating coil 1
The main piping including the auxiliary tank 16 containing the cleaning solution 11 and the auxiliary tank 16 for auxiliary storage of the cleaning liquid 11 and the safety booster pump 18 which circulates between the main tank 24 and the auxiliary tank 16 by the filter 17 at a submicron level. It constitutes the system.

A heating medium is circulated in the heating coil 15 in the preliminary tank 16 so that the cleaning liquid 11 can be heated without a sudden thermal shock. A cleaning / transporting jig 19 holding an object to be cleaned can be mounted on the servo motor 20.
There is an elevating table 22 which moves up and down by a feed screw 21 which converts the rotational movement into a linear movement in the vertical direction, so that it operates at an optimum pulling speed depending on the shape of the liquid surface of the object to be cleaned. The control box 23 manages the moving distance (current position) and the pulling speed.
Further, in order to accelerate the drying of the thin film-shaped drying liquid formed on the object to be cleaned after being pulled up from the cleaning liquid 11, an air blow 25 as a drying assisting means for applying warm air is also installed.

(Operation) The cleaning / transporting jig 19 is transported to the delivery height above the main tank 24 by the transporting system of the main body of the cleaning machine, and the cleaning / transporting jig 19 in which the object to be cleaned is set is washed at this location. From the main body transport system to the lifting platform 22 of the dryer
And the soaking and drying work is started. The rotating force of the servo motor 20 is converted into a reciprocating motion by the feed screw 21, and as a result, the lifting table 2 on which the cleaning and transporting jig 19 is mounted.
2 descends, and the object to be cleaned is immersed in the cleaning liquid 11. At this time, the cleaning liquid 11 is heat-transfer-heated by the heating coil 15 through which the heating medium flows and is heated to a predetermined temperature, and impurities such as dust at the submicron level are also removed by the circulation pump 18 and the filter 17 of 0.5 μm mesh. It is in the state of being

The soaked lift table 22 is soaked for a predetermined time and then
The ascending speed is controlled while being controlled by the control box 23 so as to have an optimum ascending speed for each height. Further, the lifting speed of the lift table 22 is optimally set by the control box 23 according to the shape and material of the object to be cleaned. After completely rising, an air blow 25 is performed to accelerate the drying of the thin film-shaped drying liquid attached to the object to be cleaned.

(Effects) The same effects as in Example 1 are obtained, and timely changes with respect to changes in the optimum pulling rate from the dry liquid surface due to the properties (surface area, surface roughness, etc.) of the object to be cleaned. It is possible to reduce the number of defects in the drying process.

In the above examples, octamethyltrisiloxane and hexamethyldisiloxane were used as the cleaning liquid. However, in addition to such organosilicon compounds, a mixture of low molecular weight polyorganosiloxane and hydrocarbon, or low molecular weight polysiloxane. Either a mixture of an organosiloxane and an alcohol or a mixture of a low molecular weight polyorganosiloxane and an ester may be used, and in this case, an azeotropic composition is particularly preferable.

The hydrocarbons used here include paraffinic, isoparaffinic and naphthenic hydrocarbons having 6 to 12 carbon atoms, and the alcohols include alcohols having 2 to 10 carbon atoms and esters. Examples of the class include esters of carboxylic acids having 1 to 6 carbon atoms and alcohols having 1 to 4 carbon atoms.

[0042]

As described above, according to the precision cleaning method and the cleaning apparatus of the present invention according to claims 1 to 4, it is possible to clean any portion with good yield regardless of the shape and material of the object to be cleaned. The heat efficiency is improved, the heat consumption is reduced, the precision cleaning quality can be secured, and the work efficiency is improved. Further, in particular, by defining the composition of the cleaning liquid used as in the invention according to claim 2, in addition to the above effect,
Further, the cleaning ability can be improved. Further, in particular, as in the invention according to claim 3, by defining the purity of the cleaning liquid to be used, in addition to the above effects, the cleaning ability can be further improved.

[Brief description of drawings]

FIG. 1 is a process diagram conceptually showing the precision cleaning method of the present invention.

FIG. 2 is a side view of the lifting step for explaining the operation of the precision cleaning method of the present invention.

FIG. 3 is a front view of a pulling step by a conventional cleaning method.

FIG. 4 is a front view showing a supported state of an object to be cleaned according to the first embodiment.

FIG. 5 is a front view of an object to be cleaned showing a cleaning result according to a comparative example.

FIG. 6 is a schematic configuration diagram showing a cleaning device according to a third embodiment.

[Explanation of symbols]

 1, 11 Cleaning liquid 2 Cleaning tank 3 Cleaning object 4 Stain 5 Dirt 16 Preliminary tank 17 Filter 19 Cleaning and conveying jig 20 Servo motor 22 Elevating table 23 Control box 24 Main tank 25 Air blow

Claims (4)

[Claims] 1. A step of immersing the object to be cleaned in a cleaning solution containing an organic silicon compound as a main component, and a step of lifting the object to be cleaned immersed in the cleaning solution from the interface of the cleaning solution at a lifting speed of 70 mm / s or less. A precision cleaning method characterized by the above. 2. The precision cleaning method according to claim 1, wherein
Organosilicon compounds have the general formula 1 The linear polyorganosiloxane represented by A precision cleaning method comprising at least one low molecular weight polyorganosiloxane selected from the cyclic polyorganosiloxanes represented by 3. The precision cleaning method according to claim 2, wherein
A precision cleaning method, wherein the cleaning liquid has a purity of 99.9 wt% or more. 4. A tank for storing a cleaning liquid containing an organosilicon compound as a main component, a circulation device for performing microfiltration while circulating this cleaning liquid to supply a clean liquid, and an object to be cleaned of 70 mm / s or less. A precision cleaning device comprising: a lifting mechanism for lifting from the liquid surface at a lifting speed; a drying assisting means for promoting drying of the lifted object to be cleaned; and a control unit for controlling the cleaning device.