JP2008161739A - Substrate cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance washability by suppressing remaining and reattachment of washing liquid containing brush chips or removed foreign matter during roll-brush washing on a substrate surface. <P>SOLUTION: In this washing method of bringing rolling brushes into contact with the substrate surface for washing while conveying the substrate, the substrate surface washed with the roll brushes is washed with a liquid stream parallel to the brush shafts and the washing liquid containing foreign matter remaining on the substrate is rapidly discharged to the outside of the substrate, to prevent reattachment. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for cleaning a substrate (glass substrate or the like) used for manufacturing a flat panel display (hereinafter referred to as FPD) such as a liquid crystal display device, an organic electroluminescence (hereinafter referred to as organic EL) display, and a plasma display. The present invention relates to a cleaning method suitable for scrub cleaning in which a rotating brush is brought into contact with the surface of the substrate while transporting the substrate.

  With the miniaturization of pixels due to high definition of liquid crystal display devices, the size of process foreign matter that causes defects in liquid crystal display devices has also become smaller. In addition, in an organic EL display having a structure in which an organic thin film is laminated between an upper electrode and a lower electrode, the thickness of the organic thin film is as thin as about 200 nm. Micron-sized foreign matter causes a non-light emitting area (dark spot) that appears black in the pixel when the organic EL display panel is turned on.

  As described above, in the manufacturing process of FPDs such as liquid crystal display devices and organic EL displays, a submicron-size foreign matter causes a device failure, and therefore the substrate surface used for this is required to have higher cleanliness. The removal of minute foreign matters is essential for improving the product yield.

  Conventionally, wet cleaning using pure water or chemicals has been applied to remove foreign substances on the surface of a substrate. See “2001 FPD Technology Taizen”, Electronic Journal, pp. A horizontal conveying type cleaning method as described in 225 to 232 is known. Wet cleaning is a method of removing foreign substances by chemical action and physical action. The chemical action is to slightly etch the substrate surface with a chemical solution to lift (lift off) foreign matter adhering to the substrate. In addition, the physical action is to apply some energy from the outside to the foreign matter attached to the substrate and remove the foreign matter. Specifically, by applying ultrasonic waves to the substrate and ejecting ultrasonic waves on the substrate by the shock wave generated when the cavitation generated by the irradiation of the ultrasonic waves breaks, ultrasonic cleaning or mist or the like is removed. There are two-fluid cleaning in which particles are sprayed onto the substrate surface together with a high-speed fluid to remove foreign substances, scrub cleaning in which a rotating brush is brought into contact with the substrate and the substrate surface is rubbed for cleaning.

  Among the above-described cleaning methods, the scrub cleaning that cleans the substrate surface while rubbing the surface of the substrate with the brush is most excellent, and is applied to a cleaning process in receiving a substrate on a mass production line.

Here, the conventional scrub cleaning which rubs a glass substrate with a roll brush is demonstrated using FIG. The substrate 100 to be cleaned is transported in the horizontal direction by the rotation of the transport rollers 101 while being supported by the plurality of transport rollers 101 on the lower surface thereof. The plurality of shower nozzles 102 arranged to face the upper surface of the substrate 100 respectively inject the cleaning liquid 103 onto the upper surface so that the substrate 100 is not dried. As a result, a liquid film 104 of the cleaning liquid 103 is formed on the upper surface of the substrate 100. The roll brush 105 for cleaning the substrate 100 has a cylindrical shape, for example, and is rotated around its axis (for example, extending in the longitudinal direction of the cylinder) by a rotation mechanism (not shown) provided in the roll brush 105. . In FIG. 4, when the substrate 100 passes between the roll brushes 105 in a direction intersecting the rotation axis, the upper surface of the substrate 100 is rubbed with each of the rotating roll brushes 105 and scrubbed. FIG. 4 shows the case where only the upper surface of the substrate is cleaned. However, when the lower surface of the substrate 100 is cleaned simultaneously with the upper surface, another set of the shower nozzle and the roll brush as described above is attached to the substrate 100. It arrange | positions so that a lower surface may be opposed. That is, the substrate 100 is inserted between a pair of the shower nozzle and the roll brush, and the upper surface and the lower surface thereof are processed.
“2001 FPD Technology Encyclopedia”, e-journal separate volume, pp. 225〜232

  However, in scrub cleaning, the substrate surface is rubbed and cleaned while the brush rotates, so that brush dust generated due to brush wear and foreign matters once removed from the substrate surface during scrub cleaning adhere to the substrate surface. To do. In this way, brush dust, foreign matter, and the like adhering to the substrate surface are also called reattached foreign matter, and deteriorate the cleanability of the substrate surface.

  In normal brush cleaning, a cleaning liquid such as pure water is supplied from the shower nozzle to the substrate surface, and its main purpose is to prevent drying of the substrate surface. This is because when the substrate after scrub cleaning is dried, the above-mentioned foreign matter adheres to the substrate surface and is difficult to be removed by subsequent cleaning. As described above, in the conventional scrub cleaning, the cleaning liquid supplied from the shower nozzle to the substrate surface is mainly intended to keep the substrate surface in a wet state. Poor ability to discharge outside.

  Further, in the FPD manufacturing process, unlike the spin cleaning in the manufacturing process of the semiconductor device in which the cleaning liquid is supplied while rotating the substantially circular substrate, the substrate is cleaned while being held horizontally and transported. Accordingly, the cleaning liquid supplied to the substrate surface is not discharged from the substrate surface due to the action of centrifugal force and tends to stay on the substrate surface, so that foreign substances contained therein are likely to reattach to the substrate surface. Further, when the substrate conveyance speed is increased, the processing time (cleaning time) is shortened, and sufficient cleaning cannot be obtained with one brush. Therefore, a plurality of brushes are usually installed to clean the substrate. As described above, when cleaning the same surface of a substrate with multiple brushes, the substrate surface on which the cleaning liquid containing foreign matter generated in the previous brush cleaning remains is scrubbed with the subsequent brush, so re-adhesion occurs. There was a problem that it was easy to do. Therefore, in order to improve the cleanliness of the substrate in scrub cleaning with the brush of the substrate transported horizontally, the cleaning liquid containing the foreign material generated after scrub cleaning with the brush is quickly discharged out of the substrate. It is necessary to suppress the reattachment of the substrate to the substrate surface.

  The present invention has been made in view of the above problems, and when cleaning the surface of a substrate while conveying the substrate (glass substrate or the like), the substrate is quickly cleaned of foreign matter once removed by brush dust or brush cleaning. It is an object of the present invention to provide a cleaning method capable of suppressing the reattachment to the substrate and improving its cleaning power by discharging to the outside.

  The gist of the substrate cleaning method according to the present invention conceived in view of the above-described problems is described as follows.

  The invention according to claim 1 (first invention of the present application) is a method for cleaning a substrate by transporting a substrate while bringing a rotating roll brush into contact with the surface of the substrate, and cleaning the substrate surface cleaned with the roll brush. , And cleaning with a liquid flow formed along the axis of the roll brush (for example, parallel to the axis).

  Invention of Claim 2 (2nd invention of this application) forms the said liquid flow along the axis | shaft of the said roll brush by injecting a washing | cleaning liquid from a linear spray nozzle in the said invention of Claim 1. It is characterized by this. The line-shaped spray nozzle is, for example, a nozzle that ejects cleaning liquid from a linear or rectangular opening (line-shaped opening), and the longitudinal direction of the opening intersects (for example, orthogonally) with the axis of the roll brush. It arrange | positions so that each of a direction and the conveyance direction of a board | substrate may be followed.

  The invention described in claim 3 (the third invention of the present application) is characterized in that, in the above invention described in claim 2, the line-shaped spray nozzle is a two-fluid spray. In the two-fluid spray, for example, a liquid and a gas are jetted together to control the shape of the liquid particles sprayed on the substrate (for example, the particle diameter is adjusted to a preferable range).

  Invention of Claim 4 (4th invention of this application) provides the ultrasonic wave to the said washing | cleaning liquid injected from the said linear spray nozzle in the said invention of Claim 2. It is characterized by the above-mentioned. is there.

  The invention described in claim 5 (the fifth invention of the present application) is characterized in that, in the invention described in claim 4, the cleaning liquid is hydrogen water in which hydrogen gas is dissolved in pure water.

  The invention described in claim 6 (sixth invention of the present application) is characterized in that, in the above invention described in claim 5, the concentration of dissolved hydrogen gas in the hydrogen water is 0.5 ppm or more.

  The invention described in claim 7 (seventh invention of the present application) is characterized in that, in the invention described in claim 5 or 6, the frequency of the ultrasonic wave is 20 kHz or more.

  According to the first aspect of the present invention, in the method of cleaning the substrate by transporting the substrate while bringing the rotating roll brush into contact with the substrate surface, the substrate follows the axis of the brush after cleaning with the roll brush (for example, parallel to the axis). By cleaning the substrate surface with a liquid flow, the cleaning liquid containing the brush dust and the foreign matter removed by the brush cleaning can be quickly discharged from the substrate. This prevents brush dust and foreign matter from reattaching to the substrate surface, thereby improving the cleaning power of the substrate. The reason for forming the liquid flow (for example, the flow of the cleaning liquid) in the direction along the brush axis (preferably parallel to the brush axis) is as follows. The roll brush that contacts from the vertical direction of the substrate that is transported horizontally forms a “weir” that is orthogonal to the horizontal plane of the substrate. Therefore, in order to quickly discharge the liquid on the substrate to the outside, the liquid (cleaning liquid that may contain brush dust and foreign matter) is flowed to the edge of the substrate using the “weir” of the brush as a guide. That is, by forming a liquid flow along the brush (rotation axis) (preferably in parallel) on the substrate surface, it becomes possible to efficiently and quickly discharge the cleaning liquid out of the substrate.

  According to the second aspect of the present invention, it is possible to uniformly form a liquid flow along (in parallel with) the axis of the brush by injecting the cleaning liquid from the line-shaped spray nozzle. As a result, the cleaning liquid containing the foreign matter staying on the substrate is quickly and uniformly discharged to the outside of the substrate, and the effect of suppressing the reattachment of the foreign matter to the substrate surface occurs.

  According to the third aspect of the present invention, in the two-fluid spray, when the mist (cleaning liquid particles) collides with the substrate, a side jet flow is generated on the substrate surface. The liquid flow along the axis of the brush can be easily formed. Therefore, there is an effect that the cleaning liquid containing the foreign matter after the brush cleaning is discharged out of the substrate, and the reattachment of the foreign matter to the substrate surface is suppressed. Moreover, since the striking force when the cleaning liquid sprayed from the two-fluid spray collides with the substrate has a power to remove foreign substances adhering to the substrate, there is an effect of increasing the cleaning power of the surface.

  The effects of the inventions according to claims 4 to 7 are as follows. In the invention according to claim 4, by applying ultrasonic waves to the cleaning liquid sprayed from the line-shaped spray nozzle, an impact force at the time of collapse of cavities (bubbles) generated in the cleaning liquid is applied to the substrate surface. Since it is possible to remove foreign substances adhering to the substrate, it is possible to improve the cleaning power of the substrate surface. Furthermore, in the invention described in claim 7, by applying ultrasonic waves of 20 kHz or higher to a cleaning solution of hydrogen water in which hydrogen gas is dissolved in pure water, the ability to remove foreign substances adhering to the substrate surface is improved, and the liquid Since there is a function of suppressing the reattachment of the foreign matter dispersed therein to the substrate surface, an effect of improving the cleaning power of the substrate surface can be obtained. Further, in the invention described in claim 5, the detergency of hydrogen water to which ultrasonic waves are applied increases as the concentration of dissolved hydrogen increases, but in order to obtain a stable detergency, claim 6 As in the invention, the dissolved hydrogen gas concentration is preferably 0.5 ppm or more. As described above, by applying ultrasonic waves to the cleaning liquid sprayed from the line-shaped spray nozzle and further applying hydrogen water to the cleaning liquid, the effect of preventing re-adhesion and the effect of removing adhering foreign matter can be enhanced, and Detergency improves.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 shows an embodiment of a cleaning method according to the present invention. The object to be cleaned 1 is a substrate used for a liquid crystal display device, an organic EL display, a plasma display, and the like, and is provided as a glass substrate, a quartz substrate, a plastic substrate, or the like. In the following description, a glass substrate is exemplified as the article 1 to be cleaned, but the material is not limited in light of the essence of the present invention.

  The surface of the object to be cleaned 1 may be formed with a device such as a TFT, even if no device is formed as in the case of bare glass. The lower surface of the object to be cleaned 1 is in contact with the plurality of transport rollers 2 and is held horizontally. Further, the cleaning object 1 is transported in the horizontal direction by a transport roller 2 that is rotated by a drive mechanism (not shown). A shower nozzle 3 is installed on the upper surface of the object 1 to be cleaned, and the cleaning liquid 4 is sprayed toward the substrate. In this example, pure water was used as the cleaning liquid. In order to prevent static electricity, pure water in which carbon dioxide gas is dissolved in pure water to reduce the specific resistance value of pure water may be applied. Further, FIG. 1 shows a case where the cleaning liquid 4 is sprayed only on the object 1 to be cleaned, but it may be sprayed on the object 1 and the roll brush 5. In each of FIG. 1 and FIGS. 2 and 3 to be described later, a thick arrow indicates a conveyance direction of the object 1 to be cleaned, and a thin arrow indicates a flow direction (liquid flow direction) of the cleaning liquid.

  The object to be cleaned 1 is scrubbed and cleaned by a roll brush 5 that is rotated by a driving mechanism (not shown). In this example, a nylon brush was applied to the roll brush. The material of the brush is not particularly limited as long as it does not damage the upper surface of the article 1 to be cleaned, and a material such as PVA (polyvinyl alcohol) may be used. On the upper surface of the object to be cleaned 1 that has passed through the roll brush 5, cleaning liquid containing brush debris and foreign matters removed by brush cleaning remains, and these foreign matters reattach to the upper surface of the object to be cleaned 1. Therefore, detergency is reduced.

  In order to discharge the cleaning liquid containing the foreign matter from the object 1 to be cleaned, a short flow of the object 1 to be cleaned is made from the line spray nozzle 6 so as to flow preferably along the axis of the roll brush 5. The cleaning liquid 7 was sprayed in the side direction. The shape of the nozzle is not limited as long as it forms a water flow that is parallel to the axis of the brush, or a nozzle in which a plurality of spot nozzles are arranged in a straight line, or the same shape showing a diameter in the range of 20 μm to 2 mm. A nozzle in which a plurality of holes (openings) are arranged in a line can also be used (in this case, the direction in which the holes (openings) are arranged is the longitudinal direction of the line spray nozzle 6).

  In this example, pure water was used as the cleaning liquid 7, and when the pure water was jetted from the line nozzle 6, an ultrasonic wave having a frequency of 1 MHz was applied to the pure water. With a water flow parallel to the brush axis formed by the line spray nozzle, the cleaning liquid containing the foreign matter after the brush is quickly discharged from the surface of the object to be cleaned 1 and is attached to the surface by using ultrasonic waves together. The effect which removes the foreign material which has been acquired is also acquired, and the washability of the to-be-cleaned object 1 improves. Further, when hydrogen water, for example, hydrogen water having a hydrogen gas concentration of 1 ppm dissolved in pure water is used as the cleaning liquid 7, the cleaning power is further improved as compared with the case where pure water is applied. This is because, in hydrogen water to which ultrasonic waves are applied, the shock wave generated when micro bubbles of dissolved hydrogen are destroyed by ultrasonic vibration, the scrub effect of micro bubbles is greater than that of pure water, and Since there is an effect of suppressing reattachment of the foreign matter removed from the substrate surface, the foreign matter removal performance is improved. In addition, if the dissolved concentration of hydrogen gas is 0.5 ppm or more, preferably 1 ppm or more, a stable foreign substance removing power can be obtained.

  Further, as shown in FIG. 2, the object 1 to be cleaned may be conveyed while being inclined in a direction perpendicular to the conveying direction. In this case, when a liquid flow parallel to the brush axis is sprayed from the upper end of the object to be cleaned 1 onto the surface of the object 1 to be cleaned, the object 1 to be cleaned is inclined, so that it is faster than in the case of horizontal conveyance. In addition, the foreign matter remaining on the substrate surface can be discharged to the outside of the substrate, so that the cleaning power is further improved.

  FIG. 3 shows another embodiment of the cleaning method according to the present invention. This embodiment shows a case where a two-fluid spray nozzle is applied as the line spray nozzle 6. The two-fluid spray nozzle applied in the present embodiment has a slit-like opening, and the fine mist 7 (pure water particles) generated by mixing pure water and air inside or outside the nozzle is opened. To the surface of the object 1 to be cleaned together with high-speed air. The distance from the opening of the nozzle to the object to be cleaned 1 may be 10 mm or less, and is preferably used at 5 mm or less. The two-fluid spray nozzle 6 is disposed vertically above the object to be cleaned 1 and perpendicular to the roll brush 5. The nozzle 6 should just be arrange | positioned on the to-be-cleaned object 1 vertical. That is, the nozzle 6 may be fixed, or the nozzle may reciprocate in a direction perpendicular to the conveyance direction of the article 1 to be cleaned.

  The fine mist 7 ejected from the nozzle opening collides vertically with the surface of the object 1 to be cleaned, and then generates a side jet flow in the horizontal direction of the surface of the object 1 to clean the foreign matter staying on the surface. The contained cleaning solution is quickly discharged out of the substrate. Thereby, the cleaning performance is improved as compared with the conventional method.

  The present invention can be used for cleaning a substrate (such as a glass substrate) used for manufacturing a flat panel display such as a liquid crystal display device, an organic EL display, and a plasma display.

It is a conceptual diagram which shows one Embodiment of the washing | cleaning method which concerns on this invention. It is a conceptual diagram which shows one Embodiment of the washing | cleaning method which concerns on this invention. It is a conceptual diagram which shows one Embodiment of the washing | cleaning method which concerns on this invention. It is a conceptual diagram which shows the conventional brush cleaning method.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,100 ... Object to be cleaned (substrate), 2,101 ... Conveying roller, 3,102 ... Shower nozzle, 4,103 ... Cleaning liquid, 5,105 ... Roll brush, 6 ... Line nozzle spray, 7 ... Cleaning liquid (micro) 104) liquid film (cleaning liquid on the object to be cleaned 1).

Claims (7)

A method of cleaning a roll brush rotating while transporting a substrate in contact with the substrate surface,
A substrate cleaning method, wherein the substrate surface cleaned with the roll brush is cleaned with a liquid flow formed along an axis of the roll brush.   The substrate cleaning method according to claim 1, wherein the liquid flow along the axis of the roll brush is formed by spraying a cleaning liquid from a line-shaped spray nozzle.   3. The substrate cleaning method according to claim 2, wherein the line-shaped spray nozzle is a two-fluid spray.   The substrate cleaning method according to claim 2, wherein an ultrasonic wave is applied to the cleaning liquid sprayed from the line-shaped spray nozzle.   The substrate cleaning method according to claim 4, wherein the cleaning liquid is hydrogen water in which hydrogen gas is dissolved in pure water.   6. The substrate cleaning method according to claim 5, wherein the dissolved hydrogen gas concentration of the hydrogen water is 0.5 ppm or more.   The substrate cleaning method according to claim 5 or 6, wherein the ultrasonic frequency is 20 kHz or more.

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