JP5116628B2 - Cleaning method - Google Patents

Description

The present invention is a cleaning object such as parts and products relates to cleaning how the object to be cleaned for cleaning by immersion in the washing solution, in particular, the washing liquid is flowed in the cleaning tank body in a substantially horizontal direction in a laminar flow state The present invention relates to an object to be cleaned by arranging an object to be cleaned in the middle of this flow.

Conventionally, the object to be cleaned such as parts and products is immersed in the cleaning liquid for cleaning, and the object to be cleaned is placed in the cleaning tank body having an opening in the upper part, and the cleaning liquid is supplied from the lower part of the cleaning tank body. On the other hand, there has been proposed a cleaning apparatus that performs cleaning by overflowing a cleaning liquid containing foreign matters such as dirt from the upper edge of the side wall of the cleaning tank body (see, for example, FIG. 2 of Patent Document 1).
JP 2008-114155 A

  However, in the cleaning apparatus as described above, the shape and specific gravity of foreign matters such as dirt adhering to the object to be cleaned are various, so depending on the specific gravity and viscosity of the cleaning liquid, or the flow rate (overflow speed, etc.) There are things that stagnate in the main body of the washing tank or settle at the bottom, and in particular, foreign substances with large specific gravity have a large tendency to settle. It is necessary to consider physical properties such as liquid specific gravity and viscosity, the types of cleaning liquids that can be used are naturally limited, and there is a problem that it is necessary to perform cleaning over time while increasing the overflow rate.

  The present invention has been made to solve the above-described problems.

The invention according to claim 1 is a method of cleaning an object to be cleaned such as a part or product immersed in a cleaning liquid, and has an inner wall erected in a substantially rectangular shape in a plan view and in a vertical direction. , In the cleaning tank body that holds the object to be cleaned and is filled with the cleaning liquid, each of the pair of opposed first inner walls and second inner walls of the inner walls of the cleaning tank body, A plurality of through holes for allowing the cleaning liquid to pass at predetermined intervals are provided over substantially the entire inner wall, and the cleaning liquid is introduced into the cleaning tank body through the first inner wall through the holes. By discharging the cleaning liquid out of the main body of the cleaning tank through the through-hole of the inner wall of 2, the cleaning liquid flows in a laminar flow state in a substantially horizontal direction from the first inner wall toward the second inner wall, Place the object to be cleaned in the middle of this flow and wash it. Is intended to, wherein the second inner wall, a liquid level substantially the same height of the washing liquid overflowing holes provided along the liquid surface, the cleaning tank body through the overflow hole A part of the cleaning liquid is discharged while overflowing, and a discharge port for discharging the cleaning liquid to the outside of the cleaning tank body is provided at the bottom in the cleaning tank body, and the cleaning tank body in the cleaning tank body is provided through this discharge port. In the case where the object to be cleaned is washed while discharging a part of the washing liquid, and there is no foreign matter that settles on the bottom of the washing tank body, the washing tank body in the washing tank body can be ignored through the discharge port. A portion of the cleaning liquid cannot be discharged, and the cleaning liquid is allowed to flow in a laminar flow state in a substantially horizontal direction from the first inner wall toward the second inner wall. the wash to wash arranged to It is a method of cleaning a thing.

According to a second aspect of the present invention, in the method for cleaning an object to be cleaned according to the first aspect, when cleaning is completed, a laminar flow state in which the cleaning liquid flows in a substantially horizontal direction from the first inner wall toward the second inner wall is maintained. It will be extracted while .

According to the method for cleaning an object to be cleaned according to claim 1, the inner wall of the cleaning tank body is predetermined on the pair of first inner wall and second inner wall facing each other over substantially the entire inner wall. A plurality of through holes for allowing the cleaning liquid to pass therethrough, and introducing the cleaning liquid into the cleaning tank body through the through holes in the first inner wall, and the cleaning liquid through the through holes in the second inner wall. Is discharged out of the main body of the cleaning tank so that the cleaning liquid flows in a laminar flow state in a substantially horizontal direction from the first inner wall toward the second inner wall, and the object to be cleaned is disposed in the middle of the flow. Therefore, the foreign matter removed from the object to be cleaned floats when the specific gravity of the foreign matter is smaller than that of the cleaning liquid, does not float when the specific gravity is equal, and sinks when the specific gravity is large. Move to the inner wall side of the second It can be discharged out of the main body of the cleaning tank through a through-hole provided over almost the entire inner wall, reducing the concentration of foreign substances in the main body of the cleaning tank and simplifying the reattachment of foreign objects to the object to be cleaned It can be reliably suppressed by a method,
The second inner wall is provided with an overflow hole along the liquid surface that is substantially the same height as the liquid surface of the cleaning liquid, and overflows a part of the cleaning liquid in the cleaning tank body through the overflow hole. Therefore, foreign matter with a small specific gravity that is removed from the object to be cleaned and floats near the surface of the cleaning liquid can be discharged to the outside of the cleaning tank body more reliably.
An outlet for discharging the cleaning liquid to the outside of the main body of the cleaning tank is provided at the bottom of the main body of the cleaning tank, and the object to be cleaned is cleaned while discharging a part of the cleaning liquid in the main body of the cleaning tank through this outlet. Therefore, even if the specific gravity of the foreign matter is larger than that of the cleaning liquid and settles on the bottom of the cleaning tank body, it can be reliably discharged out of the cleaning tank body through the discharge port.

  An embodiment of the present invention will be described with reference to FIGS. In FIG. 1, A is an embodiment of a cleaning apparatus for use in the method for cleaning an object to be cleaned according to the present invention. The cleaning apparatus A converts an object to be cleaned b such as parts and products into an organic solvent or pure water. It is immersed in a cleaning liquid m such as ultrapure water or an alkaline detergent for cleaning, and generally includes a cleaning tank body 1, a circulation pump 3, and a filter 4. The cleaning liquid m indicates the cleaning liquid before cleaning the object to be cleaned b, and the cleaning liquid m ′ indicates the cleaning liquid discharged from the cleaning tank main body 1 after cleaning the target object b and not filtered by the filter 4. Yes.

  As shown in the perspective view of FIG. 2, the cleaning tank main body 1 has an inner wall that is substantially rectangular in a plan view and is erected in the vertical direction. The cleaning tank main body 1 holds an object to be cleaned b and can store a cleaning liquid m. Is. As the cleaning object b, for example, a silicon wafer, a camera lens, a glass substrate or the like used for a semiconductor, a flat thin plate that does not hinder the laminar flow of the cleaning liquid m as described later is suitable. . Of the inner wall of the cleaning tank body 1, a pair of opposed inner walls is constituted by a first inner wall 11 and a second inner wall 12.

  Further, the cleaning liquid m can be circulated through the first inner wall 11 in a laminar flow state from the first inner wall 11 toward the second inner wall 12 over a substantially entire length of the inner wall 11. A plurality of through holes 11a, 11a,... For introducing the cleaning liquid into the cleaning tank body 1 at a certain interval, for example, arranged in a lattice shape and forming the through holes 11a at each intersection of the lattice) Similarly, the cleaning liquid m can be circulated through the second inner wall 12 in a laminar flow state from the first inner wall 11 toward the second inner wall 12 over substantially the entire inner wall 12. A plurality of through holes 12a, 12a for discharging the cleaning liquid m to the outside of the cleaning tank body 1 at such intervals, for example, through holes 12a are formed in a lattice pattern at positions facing the through holes 11a of the first inner wall 11).・ ・ Is provided. Further, the second inner wall 12 has an overflow hole that is substantially the same height as the liquid level m1 of the cleaning liquid m and that overflows a part of the cleaning liquid m outside the cleaning tank body 1 along the liquid level m1. 12b, 12b, ... (the overflow hole 12b may be plural or single).

  A discharge port 1 a for discharging the cleaning liquid m to the outside of the cleaning tank body 1 is provided at the bottom of the cleaning tank body 1.

  Meanwhile, as shown in FIGS. 1 and 2, an ultrasonic oscillator 2 that outputs ultrasonic waves for cleaning can be provided in the cleaning tank body 1. The ultrasonic oscillator 2 outputs a cleaning ultrasonic wave into the cleaning liquid m, while the cavitation effect (the foreign matter from the object to be cleaned using the shock wave generated by the bursting of the vacuum bubbles generated in the cleaning liquid by the ultrasonic wave). The object to be cleaned b is cleaned by, for example, peeling, and the cleaning effect can be further enhanced.

  The circulation pump 3 receives the cleaning liquid m ′ discharged from the through hole 12a and the overflow hole 12b of the second inner wall 12 and the discharge port 1a, and the received cleaning liquid m ′ into the cleaning tank body 1 in the first tank. The liquid is fed through the through hole 11a of the inner wall 11, for example, a known liquid feed pump.

  The filter 4 is connected to the sending side or the receiving side of the cleaning liquid m of the circulation pump 3 (in FIGS. 1 and 4 to 6 exemplarily those on the sending side of the circulation pump 3) and discharged to the outside of the washing tank body 1. The foreign matter present in the washed liquid m ′ is removed by filtration, and various filters (for example, PTFE membrane (tetrafluoroethylene resin membrane for the purpose of removing fine particles) in accordance with the properties of the foreign matter are removed. ) Etc.) can be employed.

  Next, an example of a method of cleaning the object to be cleaned b performed by the cleaning apparatus A configured as described above will be described with reference to FIGS. In this example, the object to be cleaned b is a flat and thin silicon wafer. Note that before the operation of the cleaning apparatus A, it is assumed that the valves b1 to b11 are all closed.

  First, as shown in FIG. 3, an object to be cleaned b (a plurality of silicon wafers) is placed in alignment with a jig 15 such as a washing basket, and the jig 15 is mounted in the washing tank body 1. At this time, the position of the object to be cleaned b in the cleaning tank body 1 is between the first inner wall 11 and the second inner wall 12. Moreover, the to-be-cleaned object b follows the laminar flow of the cleaning liquid m in the cleaning tank body 1 and is arranged so that the flat surface is in the vertical direction. Here, the object to be cleaned b is disposed as described above, and the object to be cleaned b is disposed and cleaned in the flow of the cleaning liquid m, and a suitable shape of the object to be cleaned b is a flat plate. In combination with this, the cleaning liquid m is prevented from disturbing the laminar flow state by the object to be cleaned b, and the foreign matter removed by promoting the flow of the cleaning liquid m in the substantially horizontal direction is removed from the second inner wall 12. This is to facilitate rapid discharge out of the cleaning tank body 1 through the through holes 12a and the overflow holes 12b. As long as the flow in the laminar flow state is not obstructed, an object other than the flat thin plate may be used as the object to be cleaned b, and the arrangement direction with respect to the flow of the cleaning liquid m is not necessarily restricted.

  Then, the opening of the cleaning tank body 1 is closed with a lid 16 to seal the cleaning tank body 1, and the valves b9 and b10 are opened and the vacuum pump 6 is operated to decompress the inside of the cleaning tank body 1. Thereafter, the valves b1 and b4 are opened in this reduced pressure state, the circulation pump 3 is operated, and the cleaning liquid m stored in the first storage tank 51 is passed through the through hole 11a of the first inner wall 11. It is introduced into the cleaning tank body 1. When the lid 16 is closed, a packing 161 may be provided between the cleaning tank body 1 and the lid 16 in order to maintain an airtight state. Further, the pressure reduction by the vacuum pump 6 is mainly for degassing the cleaning tank body 1 as shown in FIG. 4. After the cleaning liquid m is introduced into the cleaning tank body 1, the vacuum pump 6 is operated. You may deaerate.

  Thereafter, the valves b2 and b3 are opened to discharge the cleaning liquid m from the through hole 12a, the overflow hole 12b and the discharge port 1a. The cleaning liquid m ′ discharged from the through hole 12a and the overflow hole 12b is d4 by the circulation pump 3. The cleaning liquid m ′ discharged from the discharge port 1a is circulated by the circulation pump 3 along the route d5 → d2 → d3 (see FIG. 5) along the route → d1 → d2 → d3 (see FIG. 5).

  Among these, the former path is such that the cleaning liquid m flows in a laminar flow state from the first inner wall 11 toward the second inner wall 12 in a substantially horizontal direction, and mainly has a specific gravity smaller than or equal to that of the cleaning liquid m ( The cleaning tank main body 1 includes foreign substances that do not settle at the bottom of the cleaning tank main body 1 even if the specific gravity is heavy) and rides on this flow and overflows through the through hole 12a or partially through the overflow hole 12b. Discharged outside. On the other hand, in the latter path, foreign matters whose specific gravity is larger than that of the cleaning liquid m ride on the cleaning liquid m, and a part of the cleaning liquid m in the cleaning tank body 1 is discharged through the discharge port 1a. Therefore, even if the specific gravity of the foreign matter is smaller, equivalent or larger than the specific gravity of the cleaning liquid m, the foreign matter can be reliably discharged out of the cleaning tank body 1, and the concentration of foreign matter in the cleaning tank body 1 It is possible to reduce as much as possible the reattachment to the object to be cleaned b.

  Note that the flow rate ratio of the cleaning liquid m passing through these circulation paths (arrow d4 side, d5 side) can be changed as appropriate by adjusting the degree of opening of the valves b2 and b3, and the cleaning tank settles in the cleaning liquid m. If there is no foreign matter that settles at the bottom of the main body 1 or can be ignored, the valve b3 may be closed and circulated only through the former circulation path (arrow d4 side). Further, when the cleaning liquid m passes through the filter 4 located in the middle of the circulation path, foreign matters (solid matter, impurity ions dissolved in the cleaning liquid m, etc.) contained in the cleaning liquid m are removed. Therefore, the cleaning liquid m introduced into the cleaning tank body 1 is always kept in a clean state.

  When the cleaning is completed, as shown in FIG. 6, the cleaning liquid m is extracted from the cleaning tank body 1, and the valve b5 is opened to allow a part of the cleaning liquid m to flow in the direction of the arrow d6. And the valve b6 is opened, a part of the cleaning liquid m ′ is circulated in the direction of the arrow d7 and returned to the second storage tank 52. At this time, the liquid level of the cleaning liquid m in the cleaning tank body 1 gradually decreases, but in the cleaning tank body 1, the cleaning liquid m is substantially horizontally directed from the first inner wall 11 toward the second inner wall 12. Since the extraction is performed while maintaining the flowing laminar flow state, the foreign matter can be reliably discharged out of the cleaning tank main body 1 even in this extraction process, and the concentration of the foreign matter in the cleaning tank main body 1 is reduced. It is possible to minimize the reattachment to the object to be cleaned b.

  Then, when the cleaning liquid m is extracted from the cleaning tank body 1, the cleaning is generally completed, but the following steam cleaning and / or vacuum drying can be additionally performed. That is, FIGS. 7 and 8 show a steam cleaning process. The cleaning liquid m stored in the third storage tank 53 is heated by the heater 81 to be vaporized, and this steam is passed through the steam port 17. Introduced into the cleaning tank body 1 while being diffused by the baffle plate 18, the steam is brought into contact with the object to be cleaned b, cooled and liquefied, and cleaned by washing away the foreign matter remaining on the object to be cleaned b. The effect can be further enhanced. The liquefied cleaning liquid m is stored in the second storage tank 52 with the valve b6 opened (see arrow d7 in FIG. 7).

  FIG. 9 shows the vacuum drying process. The vacuum pump 6 is operated with the valves other than the valves b9 and b11 closed to depressurize the inside of the washing tank body 1, and the inside of the washing tank body 1 is shown. Evaporate and remove the remaining cleaning liquid m, etc. (including other liquids if other liquids remain). The vapor such as the cleaning liquid m removed by the vacuum pump 6 is condensed by the aggregator 7 and stored in the second storage tank 52.

  Then, the operation of the vacuum pump 6 is stopped, the valve b7 is opened, the outside air is taken into the cleaning tank body 1 and returned to the atmospheric pressure, and the lid 16 is opened as shown in FIG. b is taken out and cleaning is completed. When taking in the above-mentioned outside air, a filter f may be provided on the outside air side of the valve b7 and taken in through this filter f in order to prevent foreign matter from entering.

  By the way, in the above-described embodiment, the steam cleaning process and the vacuum drying process are performed. However, both of these processes are usually performed when an organic solvent is used in the steam cleaning process. For those that do not use a solvent (for example, those in which the cleaning liquid m is pure water), the vacuum drying step may be omitted. In such a case, the lid body is formed after the vapor cleaning step is completed. The object to be cleaned b may be taken out by opening 16.

  In FIG. 1, 82 is a heater attached to the cleaning tank body 1. When the cleaning liquid m is used at a high temperature, the cleaning tank body 1 is heated by the heater 82 to raise the temperature of the cleaning liquid m. You may make it do.

  Further, as shown in FIG. 1, when the pressure switch 61 is connected to the cleaning tank body 1 and the pressure in the cleaning tank body 1 exceeds a certain value during cleaning, the vacuum pump 6 is operated to operate the cleaning tank. It is preferable to depressurize the inside of the main body 1 to perform deaeration in the cleaning liquid m and to prevent the gas in the cleaning tank main body 1 from leaking outside.

It is the figure which showed the schematic of the washing | cleaning apparatus of the to-be-cleaned object which concerns on this invention. It is the schematic perspective view which cut and showed a part of washing tank main part of FIG. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state equipped with the to-be-cleaned object. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state which introduce | transduced the washing | cleaning liquid in the washing tank main body. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state in process of washing | cleaning of a to-be-cleaned object. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state currently discharging | emitting the washing | cleaning liquid out of the washing tank main body. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state which is performing steam cleaning additionally. It is the schematic for demonstrating a washing | cleaning process, and is partial sectional drawing cut | disconnected by the XX line of FIG. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state which is additionally performing vacuum drying. It is the schematic for demonstrating a washing | cleaning process, and is the figure which showed the state which took out the to-be-cleaned object.

Explanation of symbols

A Cleaning device b Object to be cleaned m, m 'Cleaning liquid 1 Cleaning tank body 2 Ultrasonic oscillator 3 Circulating pump 4 Filter 6 Vacuum pump 7 Aggregator

Claims (2)

In the cleaning method of the object to be cleaned, in which the object to be cleaned such as parts and products is immersed in the cleaning liquid.
It has a substantially rectangular shape in plan view and has an inner wall erected in the vertical direction, and in the cleaning tank body that holds the object to be cleaned and is filled with the cleaning liquid,
A plurality of through holes for allowing the cleaning liquid to pass through the entire inner wall of the pair of opposed first inner wall and second inner wall of the cleaning tank main body at predetermined intervals are provided in each of the pair of opposing first inner wall and second inner wall. ,
The cleaning liquid is introduced into the cleaning tank body through the through hole of the first inner wall, and the cleaning liquid is discharged out of the cleaning tank body through the through hole of the second inner wall. The cleaning liquid is made to flow in a laminar flow state in a substantially horizontal direction from the first inner wall toward the second inner wall, and the object to be cleaned is arranged and cleaned in the middle of the flow ,
The second inner wall is provided with an overflow hole along the liquid surface that is substantially the same height as the liquid surface of the cleaning liquid, and a part of the cleaning liquid in the cleaning tank body is formed through the overflow hole. Discharging while overflowing,
A discharge port for discharging the cleaning liquid to the outside of the cleaning tank body is provided at the bottom of the cleaning tank body, and the object to be cleaned is discharged while discharging a part of the cleaning liquid in the cleaning tank body through the discharge port. Wash and
When there is no foreign matter that precipitates at the bottom of the cleaning tank body or can be ignored, the cleaning liquid in the cleaning tank body is not allowed to be discharged through the discharge port, and the cleaning liquid is A cleaning method for an object to be cleaned, wherein the object is cleaned in a laminar flow state in a substantially horizontal direction from the first inner wall toward the second inner wall, and the object to be cleaned is disposed in the middle of the flow. . 2. The method for cleaning an object to be cleaned according to claim 1 , wherein when the cleaning is completed, the cleaning liquid is extracted while maintaining a laminar flow state in which the cleaning liquid flows in a substantially horizontal direction from the first inner wall toward the second inner wall. .

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