JP2836888B2 - Cleaning method for plate - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Summary] The present invention relates to a method for cleaning a plate-like object, with the object of improving the cleaning efficiency of slurry-like foreign matter, by immersing slurry-like foreign matter adhering to the surface of the plate-like body in a cleaning liquid. In the cleaning method of the plate-like body to be washed, a configuration is adopted in which a solid material which is softer than the plate-like body in the cleaning liquid and formed in a granular form is sprayed on the surface of the plate-like body.

[Industrial Application Field] The present invention relates to a method for cleaning slurry-like foreign matter from the surface of a plate-like body, for example, a ceramic substrate.

[Conventional technology]

For example, plate-like bodies such as silicon wafers and ceramic substrates are housed in a housing, and the flatness of the surface is precisely adjusted in order to form a protective film, a surface multilayer film composed of an insulating layer and a metal thin film, etc. on the surface. May be required to form. Then, in order to increase the flatness of the outer shape of the hard-to-cut material having low machinability such as silicon and ceramic, precision grinding with a lapping machine or a honing machine is performed.

In these precision grinding processes, a slurry-like polishing liquid containing a fine-grained abrasive such as diamond is supplied between a plate-like body to be processed and a tool of a polishing machine,
This polishing liquid needs to be removed until a step after polishing, for example, a step of forming a surface multilayer film composed of an insulating layer and a metal thin film layer on the surface of the ceramic substrate.

By the way, the conventional cleaning method of removing foreign matter from the surface of the plate-like body is a method of flowing a cleaning liquid to the plate-like body,
The method can be roughly classified into a method of vibrating the cleaning liquid, a method of chemically separating foreign matter from the surface of the plate-like body, and a method of using two or more of the same or different types of these methods in combination.

Examples of the method include a method of swinging a plate-like body immersed in a cleaning liquid, a method of spraying a cleaning liquid toward the plate-like body, and the like. Examples of the method include a method of ultrasonically oscillating a cleaning liquid immersed in a plate-like body, and the method of mixing a surfactant in the cleaning liquid or a method of mixing a water-soluble solvent in the cleaning liquid. Method. As a further method, for example, a large amount of bubbles are jetted into the cleaning liquid in which the plate-shaped body is immersed to generate a flow in the cleaning liquid, and the cleaning liquid is superposed by bursting the bubbles, as a method in which the method is used in combination with the above method. As an example, a method of oscillating a sound wave is given.

Note that the above method is a method of mainly removing foreign matter from the surface of the plate-like body by the dynamic pressure of the cleaning liquid to separate the foreign matter from the surface of the plate-like body. Can be said to be a method in which the chemical bond between the foreign matter and the plate-like body is dissociated by the stronger chemical bond between the foreign matter and the cleaning solution.

[Problems to be solved by the invention]

However, when attempting to clean the slurry-like polishing liquid from the ceramic substrate by these conventional cleaning methods, the surface of the ceramic substrate has a rough surface with many micro cracks, so the cleaning efficiency is low and the surface is not clean. For example, 30 to wash until the degree meets the prescribed criteria
It has been found that a fairly long time, on the order of minutes to an hour, is required.

The present invention has been made in view of the above circumstances,
It is an object of the present invention to provide a method for cleaning a plate-like body, which enables a slurry-like foreign matter adhering to the plate-like body to form a latent image with high efficiency.

[Means for solving the problem]

The present invention achieves the above object in a method for cleaning a plate-like body, in which, as shown in FIG. 1, for example, a slurry-like foreign material 9 attached to the surface of a plate-like body 1 is immersed in a cleaning liquid 3 for cleaning. In order to do so, a means is employed in which the solid material 8 which is softer than the plate-like body 1 in the cleaning liquid 3 and formed in a granular form is sprayed on the surface of the plate-like body 1.

[Action]

In the present invention, when the injected solid 8 collides with the surface of the plate 1, the plate 1 is vibrated to make the slurry foreign matter 2 easily detach from the surface of the plate 1,
The solid matter 8 scrapes off the slurry-like foreign matter 2 which has easily separated from the surface of the plate-like body 1 by a so-called mechanical force.

〔Example〕

FIGS. 1 to 3 show an example of a method for cleaning a plate and a cleaning apparatus for performing the method according to an embodiment of the present invention, in which a ceramic substrate is used as the plate. It will be described based on.

As shown in FIG. 3, the cleaning apparatus includes a cleaning tank 3 for storing a cleaning liquid 2 used for cleaning the ceramic substrate 1, a washing tank 13 for storing pure water 12, and a volatile solvent 22 such as isopropyl alcohol. It has four tanks, a draining tank 23 and a volatilizing tank 33. A heating device 31 is provided at the bottom of the volatilization tank 33, and the volatile solvent 32 such as isopropyl alcohol stored in the bottom of the volatilization tank 33 is heated by the heating device 31 to evaporate.

The ceramic substrate 1 to be treated is immersed in the cleaning liquid 2 in the cleaning tank 3 to wash the slurry-like foreign substances 9 (a part of which is shown by double hatching in FIG. 1).
13 immersed in pure water 14 and washed with water, drained in a draining tank 23 by immersing it in a volatile solvent 24 such as isopropyl alcohol, and further drained in a volatile tank 33. The cleaning is performed according to the procedure of heating by applying the vapor of the solvent 34 to evaporate the volatile solvent 24 attached to the surface.

As shown in FIG. 1, the cleaning tank 3 contains a cleaning liquid 2 for cleaning the ceramic substrate 1, and a hanger frame 4 for suspending a jig 5 for holding the ceramic substrate 1 is disposed above the cleaning liquid 2. You.

A circulation pipe 7 with a circulation pump 6 interposed is connected to one side of the steam cleaning tank 3, and the ceramic substrate 1 is placed in the cleaning liquid 2 in the cleaning tank 3 and the discharge port 7 a of the circulation pipe 7 is provided.
Suspended in front of the

The washing liquid 2 contains a bowl 8 having a diameter of about
0 pieces are inserted. This ball 8 is, as shown in FIG.
It has a chemically stable property, a main body 8a made of a fluororesin softer than the ceramic substrate 1, and a lead ball 8b embedded in the main body 8a for adjusting the specific gravity. It is set to 1.00. When the circulation pump 6 is operated, the balls 8 are jetted onto the surface of the ceramic substrate 1 on the water flow generated in the circulation pipe 7 and the cleaning tank 3.

The diameter of the ball 8 may be freely changed in consideration of the cross-sectional area of the circulation pump 6 and the circulation pipe 7 within a range that does not significantly reduce the pumping ability of the circulation pump 6. Further, the main body 8a of the ball 8 only needs to be softer than the ceramic substrate 1, and may be formed of, for example, vinyl chloride, polypropylene, polyethylene or the like. Further, a non-spherical solid can be used instead of the ball 8.

As the cleaning liquid 2, a known cleaning liquid such as pure water, a water-soluble solvent, or an aqueous solution in which a surfactant is blended with these may be used. Here, pure was used as the cleaning liquid 2 so that the cleaning effect by the injection of the ball 8 could be easily confirmed.

The ceramic substrate 1 polished by the lapping machine was cleaned by using such a cleaning apparatus.

That is, the ceramic substrate 1 on which the slurry-like foreign matter 9 containing the water-soluble abrasive and the polishing debris used for the lapping machine adheres to the entire surface is held by the jig 5, and the jig 5 is attached to the hanger frame 4. Hang the ceramic substrate 1 in the cleaning solution 2
After being suspended so as to be located in front of the discharge port 7a of the circulation pipe 7, the circulation pump 6 is operated, and a water flow having a flow rate of about 1 to 10 m / min is formed over the circulation pipe 7 and the washing tank 3. The ball 8 is placed on this water flow and the ceramic substrate 1
Spouted toward.

The ball 8 collides with the surface of the ceramic substrate 1 and, at this time, vibrates the ceramic substrate 1 so that the foreign matter 9 of the slurry is easily separated from the surface of the ceramic substrate 1. In addition, when the ball 8 collides with the ceramic substrate 1, the foreign matter 9 that has easily separated from the surface of the ceramic substrate 1 is scraped off by the ball 8 with a so-called mechanical force, so that highly efficient cleaning is performed. The slurry-like foreign substances 9 attached to the balls 8 are scraped off by the balls 8 colliding with each other, and are mixed into the cleaning liquid 2.

Then, the surface of the ceramic substrate 1 in the cleaning liquid 2 was observed to determine whether the cleaning was sufficiently performed. Here, it was determined that the washing was sufficiently performed within 5 to 10 minutes from the start of the operation of the circulation pump 6. After making this determination, the ceramic substrate 1 was turned over and the back surface was cleaned in the same procedure, and it was determined whether the back surface was sufficiently cleaned. Here, after turning over the ceramic substrate 1, 5-10
It was determined that the back surface was sufficiently cleaned in minutes. After making this determination, the ceramic substrate 1 is removed from the cleaning tank 3.
Then, it was transferred to a washing tank 13 and washed with water, immersed in a solvent 22 of a draining tank 23 for draining, and furthermore, a vapor of a volatile solvent 32 was applied in a volatile tank 33 to volatilize the solvent on the surface of the ceramic substrate 1. .

A conventional method of ultrasonically oscillating the processing result and the cleaning liquid 2 made of pure water in the cleaning tank 3 or a conventional method of supplying pressurized air to the cleaning liquid 2 made of pure water in the cleaning tank 3 to generate bubbles. After cleaning for about 30 to 1 hour in the cleaning tank 3 by the method, the results of the processes of water washing, draining, and solvent volatilization were compared and observed, and the ceramic substrate cleaned according to the embodiment of steam was observed. It was found that the cleanliness of the surface of Sample No. 1 was superior to the cleanliness of the surface of the ceramic substrate 1 cleaned according to each conventional method. That is,
It was found that the cleaning time on both the front and back sides was 10 to 20 minutes, which was 2/3 of the conventional cleaning time, and that it could be cleaned as well as the conventional method.

The ceramic substrate has been described as an example of the plate-like body,
The present invention can be used for cleaning other plate-like bodies used for electronic components, for example, silicon wafers.

〔The invention's effect〕

As described above, according to the present invention, since a solid material which is softer and more granularly formed is sprayed on the plate-shaped body in the cleaning liquid, the solid matter hits the plate-shaped body, and the surface of the plate-shaped body is hit. Slurry-like foreign matter adhering to the plate is easily separated, and the foreign matter that is easily separated from the surface of the plate-like body is mechanically rubbed by solids, so to speak, so that highly efficient cleaning is performed, and the cleaning processing time is increased. Can be shortened.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main point of a method for cleaning a ceramic substrate according to one embodiment of the present invention, FIG. 2 is a sectional view of a ball used in the method, and FIG. It is. In the figure, 1 ... ceramic substrate (plate-like body), 2 ... cleaning liquid, 8 ... ball, 9 ... ball (foreign matter).

Claims (1)

(57) [Claims] In a method for cleaning a plate-like body, the surface of the plate-like body is washed by immersing the surface of the plate-like body in a cleaning liquid. A method for cleaning a plate-shaped body, characterized by: