JPH07155714A - Ultrasonic washing device - Google Patents

Abstract

PURPOSE:To apply ultrasonic vibrations to a wash without attenuating the energy of these vibrations by applying the ultrasonic vibrations by a vibrating means via a holding means for holding the wash in a washing chamber to the wash and injecting the liquid to the surface of the wash by an injecting means. CONSTITUTION:A substrate 1 supported by a substrate supporting arm 4 is transported to an upper position of a washing chamber 5 by a transporting device and is then lowered via an aperture 20 of the washing chamber 5 so that the substrate 1 is positioned in the prescribed position in the washing chamber 5. An ultrasonic signal transmitter is driven in this state to transmit the ultrasonic vibrations generated by ultrasonic vibrator transducers 3a to 3d to the substrate 1 via substrate holding parts 2a and 2b, thereby peeling the foreign matter stuck far on the substrate surface or putting the foreign matter in an easily peelable state. Next, pure water is injected from liquid injection nozzles 6a, 6b to remove the foreign matter on the substrate surface and simultaneously to cool the substrate holding parts 2a, 2b where the heat is liable to be generated. The injection liquid after the injection is discharged together with the foreign matter from a liquid discharge port 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic cleaning device,
In particular, it relates to an ultrasonic cleaning apparatus for various substrates such as photomasks and reticles.

[0002]

2. Description of the Related Art If foreign substances such as dust adhered to a glass substrate such as a reticle or a photomask are left as they are, these foreign substances are transferred onto the wafer and cause defects in the manufactured wafer. Therefore, a cleaning method utilizing ultrasonic vibration has been conventionally proposed as one method for cleaning the contaminants attached to the substrate.

FIG. 4 is a diagram schematically showing the structure of a so-called liquid immersion type ultrasonic cleaning device. The apparatus of FIG. 4 includes a cleaning chamber 10. An ultrasonic transducer 12 is provided at the bottom of the cleaning chamber 10, and a liquid 11 as an ultrasonic transmission medium is stored in the cleaning chamber 10. In this apparatus, when the ultrasonic oscillator 12 is operated while the substrate 1 which is the object to be cleaned held by the substrate support arm 4 is immersed in the liquid 11, the ultrasonic waves use the liquid 11 as a medium to cause the surface of the substrate 1 to be exposed. Be transmitted to. Due to the action of this ultrasonic vibration, the foreign matter attached to the surface of the substrate 1 is removed.

On the other hand, FIG. 5 is a diagram schematically showing the construction of a so-called liquid jet type ultrasonic cleaning apparatus. The device of FIG.
A cleaning chamber 10 is provided. An ultrasonic transducer 13 and a nozzle 14 having a slit-shaped opening are provided on the wall of the cleaning chamber 10. In this apparatus, the substrate 1 which is the object to be cleaned held by the substrate supporting arm 4 is held at a predetermined position in the cleaning chamber 10, and ultrasonic waves are superposed while operating the ultrasonic transducer 13 (on the surface of the substrate 1). The ejected liquid is ejected from the slit-shaped opening of the nozzle 14 toward the surface of the substrate 1. Due to the action of the liquid on which the ultrasonic waves are superposed, the foreign matter attached to the surface of the substrate 1 is removed.

[0005]

In the conventional ultrasonic cleaning device as described above, since the ultrasonic transmission medium is a liquid,
The kinetic energy due to ultrasonic vibration is easily absorbed by liquid molecules and attenuated, so that a desired cleaning effect cannot be obtained. Particularly, in the above liquid immersion type ultrasonic cleaning, the foreign matter separated from the substrate surface by the cleaning floats in the liquid. For this reason, there is a disadvantage that the foreign matter once peeled off adheres to the substrate surface again.

Also in the above liquid jet ultrasonic cleaning, it is difficult to apply ultrasonic vibration to the liquid to superimpose ultrasonic waves on it, and especially when a large amount of liquid is jetted and cleaned. It is more difficult to superimpose ultrasonic waves, and the cleaning effect is significantly reduced.
The present invention has been made in view of the above problems, and the energy of ultrasonic vibration can be applied to the object to be cleaned without substantially attenuating it, and recontamination by the removed foreign matter does not occur. Another object of the present invention is to provide an ultrasonic cleaning device.

[0007]

In order to solve the above problems, in the present invention, a cleaning chamber, holding means for holding an object to be cleaned in the cleaning chamber, and the holding means for holding the object to be cleaned are provided. There is provided an ultrasonic cleaning apparatus comprising: a vibrating unit for applying ultrasonic vibration to a cleaning target; and an ejecting unit for ejecting a liquid onto the surface of the cleaning target.

According to a preferred embodiment, the holding means is made of a material having a cubic close-packed structure such as aluminum, nickel or copper or a hexagonal close-packed crystal structure such as zinc or magnesium and having a high atomic packing ratio. Further, it is preferable that the vibrating means is an ultrasonic transducer arranged so as to apply ultrasonic vibration in two directions substantially parallel to the surface of the object to be cleaned.

[0009]

In the ultrasonic cleaning apparatus of the present invention, ultrasonic vibration is applied to the substrate through the holding means for holding the substrate which is the object to be cleaned. That is, by using a solid such as the holding means, the ultrasonic vibration energy of the vibrator can be efficiently transmitted to the substrate without being substantially attenuated. The holding means is made of a material having a crystal structure with a high atomic packing rate, that is, a solid crystalline material having a hexagonal close-packed structure or a cubic close-packed structure so that the attenuation of ultrasonic vibration energy due to vibration absorption is minimized. preferable.

As described above, the liquid is jetted toward the surface of the substrate while applying the ultrasonic vibration to the substrate through the holding means, so that the liquid is separated from the surface of the substrate or is about to be separated by the action of the ultrasonic vibration. The foreign matter is promptly removed and discharged from the substrate surface. This avoids recontamination as occurs in the prior art. Also, regarding the problem of heat generated when ultrasonic vibration is applied to a solid,
This can be solved by the cooling effect of the ejected liquid. That is, it is possible to avoid harmful heat transfer to the substrate by spraying a liquid such as pure water on at least the holding portion of the substrate holding means that is in contact with the substrate to cool the substrate. Further, for example, by configuring the ultrasonic vibration so that it can be applied in two directions parallel to the substrate surface (simultaneously or alternately), compared with the conventional case where the ultrasonic vibration is applied in only one direction. As a result, foreign matter is easily peeled off from the substrate surface, and the so-called peeling effect is doubled.

[0011]

Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a diagram schematically illustrating the configuration of an ultrasonic cleaning device according to an embodiment of the present invention. Further, FIG. 2 is a diagram schematically illustrating the configuration of the substrate holding means of FIG.
The apparatus of FIG. 1 comprises a cleaning chamber 5. An opening 20 is provided in the upper portion of the cleaning chamber 5, and the opening 2
A substrate 1 such as a reticle, which is an object to be cleaned, is supported by a substrate supporting arm 4 and is introduced into the cleaning chamber 5 via 0. The substrate support arm 4 is a driving device 7
And is configured to be able to reciprocate up and down in the drawing in the cleaning chamber 5.

An exhaust port 8 is provided on the upper side wall of the cleaning chamber 5, and a drain port 9 is provided on the lower part. Also,
In the cleaning chamber 5, two liquid jet nozzles 6a and 6a are provided.
b is provided. Each liquid ejecting nozzle 6 is connected to a liquid supply device (not shown) for supplying a liquid such as pure water so that the liquid can be ejected toward the surface of the substrate 1 held at a predetermined position. Has become. As shown in FIG. 2, the substrate holding means includes a pair of substrate support arms 4a.
And 4b. Substrate holders 2a and 2b are provided inside the lower ends of the pair of substrate support arms 4a and 4b, respectively, and the substrate 1 can be held by the substrate holders 2a and 2b.

The substrate holders 2a and 2b are made of a material having a high atomic packing rate, such as N, so that ultrasonic vibration energy can be transmitted to the substrate 1 without being substantially attenuated.
i, Al, Cu cubic close-packed structure or Zn,
It is preferably made of a material having a hexagonal close-packed structure such as Mg. The substrate holder 2a is provided with an ultrasonic transducer 3a in the vertical direction in the figure and an ultrasonic transducer 3c in the horizontal direction in the figure. On the other hand, in the substrate holding portion 2b, the ultrasonic transducers 3b are arranged in the vertical direction in the figure and the ultrasonic transducers 3b are arranged in the horizontal direction in the figure.
d is provided. Thus, the substrate 1 becomes the substrate holder 2
It is configured to vibrate ultrasonically in the vertical direction (indicated by arrow A) and the horizontal direction (indicated by arrow B) in the figure via a and 2b.

The operation of the ultrasonic cleaning apparatus of this embodiment having the above construction will be described below. The substrate 1 supported by the substrate support arm 4 is transferred to a position above the cleaning chamber 5 by a transfer device (not shown). Then, the substrate supporting arm 4 is lowered by the driving device 7 through the opening 20 of the cleaning chamber 5, and the substrate 1 supported by the substrate supporting arm 4 is held at a predetermined position in the cleaning chamber 5. When the substrate 1 is held at a predetermined position in the cleaning chamber 5, the ultrasonic oscillator 3 starts ultrasonic vibration by an ultrasonic oscillator (not shown). The ultrasonic vibrations of the ultrasonic oscillator 3 are efficiently transmitted to the substrate 1 via the substrate holding portions 2a and 2b, and the substrate 1 is vertically (indicated by arrow A) and horizontally (indicated by arrow B) in the figure. It vibrates ultrasonically.

Due to the action of ultrasonic vibration, the foreign matter adhering to the surface of the substrate is peeled off or easily peeled off. On the other hand, the substrate supporting arm 4 repeats the vertical reciprocating movement in the figure by the driving device 7 so as to be interlocked with the ultrasonic vibration of the ultrasonic oscillator 3, and the pure water is discharged from the liquid jet nozzle 6 onto the surface of the substrate 1 and the substrate. It is jetted toward the holding portions 2a and 2b. Thus, the foreign matter that has already been separated from the surface of the substrate 1 and is floating around the periphery of the substrate surface and the foreign matter that is about to be separated from the substrate surface are removed by the action of the liquid jet, and at the same time, the ultrasonic vibration causes heat to be generated. The substrate holders 2a and 2b, which are likely to occur, are effectively cooled.

The foreign matter separated from the surface of the substrate 1 and dropped and the foreign matter taken into the jet liquid and removed from the substrate surface are discharged to the outside of the cleaning chamber 5 through the drain port 9. Further, the mist generated in the cleaning chamber 5 is discharged to the outside of the cleaning chamber 5 via the exhaust port 8. In this way, so-called recontamination, in which foreign matter once removed from the surface of the substrate 1 reattaches to the surface of the substrate 1, is avoided.

As the liquid jetted from the jet nozzle, it is preferable to use pure water in which C0 ₂ or O ₃ is dissolved in order to prevent the electrification of the substrate. Further, a chemical solution having a chemical dissolving power such as ammonia water or a solvent may be used. The injection nozzle may be of a type having a slit-shaped opening, or may be of a type having a fan-shaped opening. Further, it is possible to avoid the reciprocating movement of the substrate during the cleaning process by appropriately disposing a plurality of fan-shaped jet nozzles so as to cover the entire surface of the substrate and the substrate holding portion.

Next, a modified example of the substrate holding means will be described.
FIG. 3 is a view showing a modified example of the substrate holding means of FIG.
It is a figure which shows the board | substrate holding means which can give an ultrasonic vibration to all four sides of a board | substrate. In the above-described embodiment, the vibrators 3c and 3d for applying ultrasonic vibration in the vertical direction are provided only on the upper surface of the substrate. However, as shown in FIG. 3, the vibrators 3e and 3f may be added to the lower surface of the substrate. Thereby, the cleaning effect can be enhanced. Further, in the above-described embodiment, the oscillator having a constant frequency is used, but two types of oscillators, a low frequency oscillator and a high frequency oscillator, may be used.
For example, in FIG. 3, a low frequency oscillator of 20 to 40 kHz and a high frequency oscillator of 400 kHz to 1 MHz are
They can be attached to the left and right and the upper and lower sides of the board in the figure, respectively. In this way, it is possible to remove relatively large foreign matter by operating the low-frequency oscillator and remove fine foreign matter by operating the high-frequency oscillator. In this case, the two types of vibrators may be operated separately or simultaneously.

In the embodiment shown in FIG. 2, ultrasonic vibrations are simultaneously applied in two orthogonal directions substantially parallel to the surface of the substrate, but in the case of FIG. 2 it may be applied alternately in the two orthogonal directions. Further, in any of the cases shown in FIGS. 2 and 3, the other two appropriate crossing directions may be simultaneously or alternately applied. In addition, after the substrate surface is made hydrophilic by irradiation with ultraviolet rays or the like, a higher cleaning effect can be exhibited by using the ultrasonic cleaning device of the present invention.

[0020]

As described above, in the ultrasonic cleaning apparatus of the present invention, since the solid that has little vibration absorption is used as the ultrasonic transmission medium, the ultrasonic vibration energy can be applied to the substrate extremely efficiently. . Further, since the liquid is jetted onto the substrate surface and the substrate holding means at the same time as the ultrasonic vibration is applied, the foreign matter separated by the ultrasonic vibration is taken into the liquid and discharged to the outside of the cleaning chamber. Therefore, recontamination of the substrate by the foreign matter once removed is avoided, and the substrate holding means is effectively cooled. Furthermore, since ultrasonic vibration is applied to the substrate in two directions simultaneously or alternately, the effect of removing foreign matter is doubled.

[Brief description of drawings]

FIG. 1 is a diagram schematically illustrating a configuration of an ultrasonic cleaning device according to an embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a configuration of a substrate holding unit of FIG.

FIG. 3 is a diagram showing a modification of the substrate holding means.

FIG. 4 is a diagram schematically showing a configuration of a conventional liquid immersion type ultrasonic cleaning device.

FIG. 5 is a diagram schematically showing a configuration of a conventional liquid jet ultrasonic cleaning device.

[Explanation of symbols]

 1 Substrate 2 Substrate Holding Unit 3 Ultrasonic Transducer 4 Substrate Support Arm 5 Cleaning Chamber 6 Liquid Injection Nozzle 7 Driving Device 8 Exhaust Port 9 Drainage Port 20 Opening

Claims (3)

[Claims] 1. A cleaning chamber, holding means for holding an object to be cleaned in the cleaning chamber, vibrating means for applying ultrasonic vibration to the object to be cleaned via the holding means, and An ultrasonic cleaning device, comprising: an ejecting unit for ejecting a liquid onto the surface of the object to be cleaned. 2. The ultrasonic cleaning apparatus according to claim 1, wherein the holding means is made of a material having a cubic close-packed crystal structure or a hexagonal close-packed crystal structure and having a high atomic packing rate. 3. The vibrating means is an ultrasonic transducer arranged so as to apply ultrasonic vibrations in two directions substantially parallel to the surface of the object to be cleaned.
Or the ultrasonic cleaning device according to 2.