JP2658963B2 - Cleaning device for charged particles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning apparatus, and in particular, applies a DC voltage and ultrasonic waves in a cleaning tank so as not to charge an object to be cleaned such as a glass or a silicon wafer to remove charged particles adsorbed on the surface. It is a cleaning device that removes and prevents re-adhesion after removal to obtain a clean surface.

[0002]

2. Description of the Related Art As a conventional cleaning apparatus used for cleaning a semiconductor substrate, an electrode is provided in a water bath, an object to be cleaned such as a semiconductor substrate (referred to as "substrate to be cleaned") is immersed, and an electric field is applied thereto. An apparatus for removing impurities on the surface of a cleaning object has been proposed (see, for example, JP-A-3-82029, JP-A-4-75339, JP-A-2-303027, etc.). FIG. 3 is a view for explaining the principle of cleaning a particle removing device using a DC applied voltage as a conventional cleaning device.

As shown in FIG. 3, electrodes 34 and 35 are placed in a cleaning tank 30 filled with pure water 37, an object 33 to be cleaned is placed between them, and a voltage is applied to the electrodes 34 and 35 from a power supply 36. , Electrodes 34, 35
By applying an electric field between them, the positively charged particles 31 adsorbed on the surface of the object 33 to be cleaned move to the negative electrode 35 (in the direction of the arrow in the figure), and the negatively charged particles 32 move to the positive electrode 34. (In the direction of the arrow in the figure) to clean the surface of the object 33 to be cleaned.

[0004]

However, in the above-described conventional cleaning apparatus, first, charging of the surface of the object 33 to be cleaned is not considered. When a voltage is applied to the electrode, as shown in FIG. 3, the object 33 itself is polarized and the surface on the positive electrode side becomes negative,
The surface on the negative electrode side is positively charged.

In this state, for example, the negatively charged particles 32 can be removed from the surface of the cleaning object 33 on the positive electrode side, but the remaining positively charged particles 31 are more strongly bound on the surface by Coulomb force, and are removed. However, there is a concern that new positively charged particles may adhere.

Next, in the conventional cleaning apparatus, since only one direction of electric field is applied, only one of positive and negative charged particles can be removed from the surface of one of the objects to be cleaned 33. That is, the positive charged particles 31 remain on the positive electrode 34 side,
The negative charged particles 32 remain on the negative electrode 35 side.

[0007] Even if the direction of the electric field is reversed, only one cleaning tank is provided, so that the charged particles once trapped on the surface of each electrode migrate due to the reverse electric field, and again. It adheres to the surface of the object 33 to be cleaned.

Accordingly, the present invention solves the above-mentioned problems of the prior art, prevents the surface of the object to be cleaned from being charged, promotes the desorption of the adsorbed species by applying ultrasonic waves, and reduces An object of the present invention is to provide a cleaning apparatus that can remove all charged particles by applying both positive and negative electric fields.

[0009]

In order to achieve the above object, the present invention comprises one or more pairs of electrodes parallel to each other,
The apparatus includes at least first and second liquid tanks that are immersed in a cleaning liquid and disposed between the electrodes to perform cleaning.
In the liquid tank, an electric field in a predetermined direction is applied between the pair of electrodes to wash the object to be cleaned. In the second liquid tank, an electric field opposite to the direction of the first liquid tank between the pair of electrodes in the second liquid tank. And a cleaning device configured to clean the object to be cleaned.

In the present invention, preferably, an ultrasonic wave generating means is provided in the liquid tank, and ultrasonic waves are applied to the surface of the object to be cleaned to separate charged particles.

In the present invention, preferably, the object to be cleaned is grounded.

[0012]

According to the present invention, all the charged particles on the surface of the object to be cleaned can be removed by performing two-stage cleaning in two tanks to which electric fields in opposite directions are applied. Also,
By applying ultrasonic waves, both positive and negative charged particles adsorbed on the surface of the object to be cleaned can be efficiently desorbed from the surface of the object to be cleaned. Furthermore, according to the present invention,
By providing the ground to the object to be cleaned, the surface is prevented from being charged, and the reattachment of charged particles is avoided, so that an extremely clean surface can be obtained.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a view showing a schematic configuration of a cleaning apparatus according to one embodiment of the present invention, and FIG. 2 is a view for explaining the principle of cleaning.

Referring to FIG. 1, in this embodiment, two cleaning tanks 10 and 11 are provided for performing two-step cleaning. First tank 10
The second tank 11 and the second tank 11 are both filled with pure water 12, and a plurality of pairs of flat electrode 2 and negative electrode 3 are provided. In FIG. 1, the electrodes are arranged in parallel in the horizontal direction, but may be arranged in the vertical direction.

The surfaces of the electrodes 2 and 3 are covered with an insulating film (not shown) to prevent electrochemical reactions such as electrolysis of water. The object to be cleaned 1 is placed in parallel between the positive electrode 2 and the negative electrode 3, and a ground 5 is connected to the object to be cleaned 1.

Further, an ultrasonic wave generating plate 4 is provided on the wall surface of the container to promote desorption of charged particles.

As shown in the figure, as the number of electrode sets is increased, the number of objects to be cleaned 1 which can be cleaned at one time increases.

After the cleaning in the first tank 10 is completed, the object 1 to be cleaned is maintained in the second tank 10 while maintaining the positional relationship with the electrodes in the first tank 10.
Move to tank 11. For example, the object to be cleaned at the top of the first tank 10 in FIG. 1 is placed between the electrodes at the top of the second layer 11. Second
The direction of the applied electric field in the tank 11 is opposite to that in the first tank 11.

Referring to FIG. 2, the principle of cleaning in this embodiment will be described. FIG. 2 shows only a pair of electrodes 2 and 3 among a plurality of sets of electrodes of the present embodiment shown in FIG.

It is assumed that positively charged particles 21 and negatively charged particles 22 adhere to the surface of the object 1 to be cleaned. Since the direction of the electric field in the first tank 10 is from the positive electrode 2 to the negative electrode 3, the object to be cleaned 1
On the surface on the side of the positive electrode 2, the negatively charged particles 22 are desorbed by receiving a force in the direction of the positive electrode 2, migrate to the positive electrode 2 and are held there. On the surface of the cleaning object 1 on the side of the negative electrode 3, the positively charged particles 21 are desorbed by receiving a force in the direction of the negative electrode 3.
And is retained there. Further, in the present embodiment, an ultrasonic wave is applied from the ultrasonic wave generating plate 4 of FIG. 1 in order to promote the desorption of the charged particles.

At this stage, positive charged particles remain on the surface of the object 1 to be cleaned on the positive electrode 2 side, and negative charged particles remain on the surface of the object 1 to be cleaned 1 on the negative electrode 3 side.

In the above-described conventional cleaning apparatus, cleaning has been completed here. In addition, as shown in FIG. 3, in the conventional cleaning apparatus, since the ground is not attached to the cleaning target 33, the surface of the cleaning target 33 is charged, so that the adsorption power with the residual charged particles is reduced. Had become stronger.

On the other hand, in the present embodiment, as shown in FIG. 2, the object 1 to be cleaned proceeds to the second tank 11 in order to remove residual charged particles. Further, since the ground 1 is attached to the object 1 to be cleaned, the surface of the object 1 to be cleaned is not charged, so that the adsorption power of the residual charged particles is weaker than that of the conventional cleaning apparatus.

In the second tank 11, an electric field in a direction opposite to that of the first tank 10 is applied to the object 1 to be cleaned. As a result, the positive charged particles 27 remaining on the surface of the object 1 to be cleaned on the negative electrode 7 side become negative. The negatively charged particles 28 remaining on the surface on the opposite side of the object 1 to be cleaned are desorbed by receiving a force in the direction of the positive electrode 8.

As described above, according to this embodiment, all charged particles on the surface of the object to be cleaned can be removed by performing the two-stage cleaning. Further, by providing a ground to the object to be cleaned, charged particles are prevented from re-adhering to prevent charging of the surface, and a clean surface can be obtained.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited to only the above embodiments.
Various modes according to the principle of the present invention are included.

[0027]

As described above, according to the present invention,
By performing two-stage cleaning in two tanks to which electric fields in opposite directions are applied, all charged particles on the surface of the object to be cleaned can be removed, and by applying ultrasonic waves, the surface of the object to be cleaned can be removed. This has the effect that both the positive and negative charged particles adsorbed on the surface can be efficiently desorbed from the surface of the object to be cleaned. Furthermore, according to the present invention, since the surface is prevented from being charged by providing the ground to the object to be cleaned, there is no re-attachment of charged particles, and a very clean surface can be obtained.

[Brief description of the drawings]

FIG. 1 is a view showing a cleaning apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating a cleaning principle of one embodiment of the present invention.

FIG. 3 is a diagram illustrating a conventional cleaning device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 To-be-cleaned object 2,8 Positive electrode 3,7 Negative electrode 4 Ultrasonic generation plate 5 Ground 6,6 'Power supply 10 1st tank 11 2nd tank 12 Pure water 21,27 Positive charged particles 22,28 Negative charge particle

Claims (6)

(57) [Claims] 1. An apparatus according to claim 1, further comprising one or more pairs of electrodes parallel to each other, at least first and second liquid tanks for immersing in a cleaning liquid and arranging an object to be cleaned between said electrodes for cleaning. In the liquid tank, an electric field in a predetermined direction is applied between the pair of electrodes to wash the object to be cleaned, and in the second liquid tank, an electric field opposite to the direction of the first liquid tank between the pair of electrodes in the second liquid tank. And a cleaning device configured to clean the object to be cleaned by applying pressure. 2. After the object to be cleaned is cleaned in the first liquid tank, the object to be cleaned is cleaned in the second liquid tank in the same arrangement state as that in the first liquid tank. The cleaning device according to claim 1, wherein 3. The cleaning apparatus according to claim 1, wherein an ultrasonic wave generating means is provided in the liquid tank, and charged particles are desorbed by applying ultrasonic waves to the surface of the object to be cleaned. . 4. The cleaning apparatus according to claim 1, wherein the object to be cleaned is grounded. 5. The cleaning apparatus according to claim 1, wherein a DC electric field is applied between said pair of electrodes. 6. The cleaning apparatus according to claim 1, wherein the cleaning liquid is pure water.