JPH05217979A - Removing method of adhered fine particle and removing device therefor - Google Patents

Abstract

PURPOSE:To permit the easy and sure removal of fine particles, adhered to the surface of a matter to be washed by electrostatic attractive force. CONSTITUTION:A magnetic field 23, orthogonal to the surface of a semiconductor water 14, is impressed on the wafer 14 while rotating the semiconductor wafer 14 by an upper electromagnet 15 and a lower electromagnet 16 to provide fine particles 21, adhered to the surface of the semiconductor wafer 14, with a kinetic energy through Fleming's left-hand rule whereby the adhered fine particles 21 are removed out of the surface of the semiconductor wafer 14.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for removing adhered particles, and more particularly to a method and apparatus for removing particles adhering to the surface of an object to be cleaned by electrostatic attraction. ..

[0002]

2. Description of the Related Art Conventionally, in order to remove particles or the like adhering to the surface of a semiconductor wafer, which is an object to be cleaned, the semiconductor wafer is rotated and supplied with cleaning water or the like on the surface of the wafer. It was done by moving the brush. A cup type brush scrubbing device shown in FIG. 5 and a cylindrical brush scrubbing device shown in FIG. 6 are known as typical surface treatment devices.

In the cup-type brush scrubbing apparatus, as shown in FIG.
The brush 53 made of nylon or the like is attached to the cup-shaped jig 54 while being rotated by being carried by the surface 2, and the surface treatment is performed while sweeping the brush 53 with the arm 56 while supplying the cleaning liquid 55 onto the semiconductor wafer 51. It is configured to do.

On the other hand, in the cylindrical brush scrubbing apparatus, as shown in FIG. 6, nylon jigs 58 are radially provided on the outer peripheral surface of a cylindrical jig 57 to rotate the semiconductor wafer 51. The cylindrical brush 58 is rotated and the cleaning liquid 55 is used to remove fine particles adhering to the semiconductor wafer 51.

Particle maps before and after brush scrubbing in these devices are shown in FIGS. 7 (a) and 7 (b). First, FIG.
The fine particle map of (a) is a fine particle map after a semiconductor wafer, for example, silicon is thermally oxidized and an oxide film thickness is grown to about 100 nm, and is 0.16 μm or more. FIG. 7B shows a fine particle map when this semiconductor wafer is brush scrubbed.

[0006]

In the method of removing fine particles by brush scrubbing, the adhered fine particles are mechanically removed by rotating the semiconductor wafer and rotating and pressing the brush, and are generated by the rotation of the semiconductor wafer. The cleaning liquid is discharged to the outside of the wafer by centrifugal force. FIG. 8 schematically shows this, and since the brush 60 causes friction on the oxide film surface of the insulator,
The adhered fine particles 59 and the oxide film 61 are charged with static electricity. Therefore, there is a drawback that the fine particles 59 once removed from the surface of the semiconductor wafer 62 immediately adhere to the semiconductor wafer 62 again.

Further, since the brush 60 is made of a dielectric material such as nylon, the fine particles also adhere to the brush 60 and are carried to the central portion of the wafer, and particles are also generated from the brush itself. In the central portion of the wafer, the centrifugal force generated by the rotation of the semiconductor wafer is small, and as a result, as shown in FIG.

FIG. 9 shows a map of the adhered particles before and after brush scrubbing the particles of the insulating material adhered to the back surface by the rubber belt conveyance. Immediately after the conveyance of FIG. 9A, the conveyance trace 63 of the conveyance belt is clearly shown. As shown in FIG. 9B, since the transfer trace 63 is mechanically separated from the wafer surface temporarily by the brush scrubbing process, the transfer trace 63 is small, but it is immediately charged with static electricity. Redeposit on the wafer. For this reason, there is a drawback in that the fine particles adhered in the transfer section are scattered only on the entire surface of the wafer and are not removed at all.

The present invention has been made in view of the above points, and is a method for removing adhered particles capable of easily and surely removing particles adhering to the surface of an object to be cleaned by electrostatic attraction. And its removal device.

[0010]

In order to achieve the above object, the method for removing adhered fine particles according to the present invention is such that an object to be cleaned is moved parallel to the surface thereof while being perpendicular to the surface of the object to be cleaned. A strong magnetic field is applied. Also,
An apparatus for removing adhered fine particles according to the present invention comprises a moving means for moving an object to be cleaned parallel to its surface, and a magnetic field generating means for generating a magnetic field perpendicular to the surface of the object to be cleaned. Is becoming

[0011]

[Function] By applying a magnetic field perpendicular to the surface of the object to be cleaned that is moving in a plane parallel to the surface, the particles adhering to the surface of the object to be cleaned are subjected to Fleming's left-hand rule. Kinetic energy is given. By giving kinetic energy to the adhered particles, the particles are removed out of the surface of the object to be cleaned.

[0012]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a block diagram of an embodiment of a particle removing device according to the present invention applied to a cup type brush scrubbing system. In the figure, a cup-shaped brush 11 is made of nylon or the like and supported by a brush supporting portion 12, and is driven by an upper arm 13 to swing on a semiconductor wafer (hereinafter, simply referred to as a wafer) 14 to perform a scrubbing process. .. Inside the brush supporting portion 12, an upper electromagnet 15 including a highly magnetic permeable material and a coil wound around the highly magnetic permeable material is installed.

On the other hand, below the wafer 14, a lower electromagnet 16 having the same structure as the upper electromagnet 15 is installed so as to correspond to the upper electromagnet 15. This lower electromagnet 16
Is fixed to the lower arm 18 via a cover 17 that prevents the washing water 22 from getting wet. The upper electromagnet 15 and the lower electromagnet 16 are supplied with a current in a direction in which the magnetic pole surfaces facing each other are the N pole and the S pole.
On the other hand, a magnetic field 23 perpendicular to the surface is applied.

The wafer 14 is attracted by the attraction plate 19 so as to be located between the upper electromagnet 15 and the lower electromagnet 16.
It is carried and rotated by a drive source (not shown) via the rotary shaft 20. Fine particles 21 are attached to the surface of the wafer 14, and cleaning water 22 is supplied onto the surface of the wafer 14 in order to remove the fine particles 21. Pure water is generally used as the cleaning water 22.

Next, the operation of the particulate matter removing device thus constructed will be described. First, in order to remove the fine particles 21 attached to the surface of the wafer 14, the wafer 14 is rotated by the rotating shaft 20 and the brush 11 is pressed against the wafer 14 to mechanically remove the fine particles 21 from the wafer 14.
A process of peeling from the surface is performed. Brush 1 at this time
1 is electrostatically charged by friction between the fine particles 21 and the wafer 14, and the charging polarity and the strength of the fine particles 21 are determined by the composition of the fine particles 21, the surface composition of the wafer 14, the rotation speed of the wafer 14, or the conductivity of the cleaning water 22. It depends on the situation.

In the following description, the operation will be described on the assumption that the particles 21 are charged to a negative potential. Particles 21 charged to the negative potential ^- is by traversing a medium magnetic field 23 at a rotational speed of the wafer 14, the kinetic energy given as described below. That is, in the operation principle diagram of FIG. 2, when the negatively charged fine particles 21 ⁻ pass through the magnetic field 23 created by the electromagnets 15 and 16 in the direction of arrow A, the current flows in the direction shown by arrow B. now, this by fine particles 21 ^-
Is given kinetic energy in the direction indicated by arrow C.

This is because, in FIG. 3, when a current flowing from the front surface side to the back surface side of the paper flows in the magnetic field 33 directed from the N extreme surface of the magnet 31 to the S extreme surface of the magnet 32, the magnetic field 33 enters the magnetic field 33. This is because the existing fluid 34 is given kinetic energy in the direction of arrow D in the figure according to Fleming's left-hand rule. In this embodiment, as a means for generating the magnetic field 33, as shown in FIGS.
Although 5, 16 are used, the present invention is not limited to this.
However, by using the electromagnets 15 and 16, the magnetic field direction and strength can be controlled according to the direction and magnitude of the current supplied to the coil of each electromagnet.

In this way, if the direction of the kinetic energy applied to the fine particles 21 is the same as the direction of the centrifugal force generated by the rotation of the wafer 14, that is, the end surface of the upper electromagnet 15 on the wafer 14 side is the N pole, and the lower electromagnet 16 is. Wafer 14
When the side end face is the S pole, the re-adsorption of the fine particles 21 due to static electricity can be suppressed in combination with the effect of discharging the fine particles by the cleaning water 22. Further, by disposing the upper electromagnet 15 inside the brush supporting portion 12, the mechanically removed fine particles 21 can be immediately removed to the outside of the surface of the wafer 14 by the magnetic field.

On the other hand, due to the surface composition of the wafer 14 and the composition of the adhered fine particles 21, when the fine particles 21 are charged to a positive potential, the direction of the current flowing through each coil of the upper electromagnet 15 and the lower electromagnet 16 is changed. Allows the upper electromagnet 15
Of the lower electromagnet 16 as the south pole and the wafer 14 side end surface of the lower electromagnet 16 as the north pole, the magnetic field direction is reversed by 180 °, and the movement direction of the fine particles 21 ⁺ charged to a positive potential is generated by the rotation of the wafer 14. Can be direction. Moreover, since the electromagnet is used, the magnetic field strength can be freely adjusted.

In the above-mentioned particulate removing device, the upper electromagnet 15 and the lower electromagnet 16 are moved so as to face each other by the upper arm 13 and the lower arm 18, but in a general brush scrubbing device, it is shown in FIG. Thus, the movement of the lower arm 18 will be limited by the rotation axis 20. Therefore, the attraction plate 19 is made of a highly magnetically permeable material such as permalloy coated with Teflon or the like to have substantially the same size as the wafer 14, so that the magnetic field generated by the upper electromagnet 15 and the magnetic field generated by the lower electromagnet 16 are buffered. Magnetic field 2 which becomes stronger and is incident on the wafer 14.
The efficiency of 3 can be improved.

In the above embodiment, the case where the object to be cleaned is a semiconductor wafer has been described, but the present invention is not limited to this, and it is applicable to all objects to be cleaned to which fine particles easily adhere due to electrostatic attraction. Is. Further, in the above embodiment, since the object to be cleaned is a semiconductor wafer, the magnetic field is applied while rotating the semiconductor wafer, but the invention is not limited to rotation, and rotation is included in the concept of movement. I shall.

[0022]

As described in detail above, according to the present invention, by applying a magnetic field perpendicular to the surface of the object to be cleaned while moving the object to be cleaned in parallel with the surface, Since the kinetic energy is given to the particles adhering to the surface of the object to be cleaned by the Fleming's left-hand rule, the adhering particles can be easily and surely removed by this kinetic energy.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a particle removing device according to the present invention.

FIG. 2 is a diagram showing the operating principle of the particle removing device according to the present invention.

FIG. 3 is a principle diagram of Fleming's left-hand rule.

FIG. 4 is a configuration diagram showing a modified example of the present invention.

FIG. 5 is a configuration diagram of a cup-type brush scrubbing device.

FIG. 6 is a configuration diagram of a cylindrical brush scrubbing device.

FIG. 7 is a particle map diagram in a conventional example.

FIG. 8 is a schematic view of a brush scrub.

FIG. 9 is a fine particle map diagram of adhesion on the back surface by a rubber belt.

[Explanation of symbols]

 11 cup type brush 13 upper arm 14 semiconductor wafer 15 upper electromagnet 16 lower electromagnet 18 lower arm 19 adsorption plate 21 fine particles 22 cleaning water

Claims (2)

[Claims] 1. A method for removing adhered fine particles for removing fine particles adhering to the surface of an object to be cleaned, which comprises moving the object to be cleaned parallel to the surface of the object to be cleaned. A method for removing adhered fine particles, which comprises applying a magnetic field perpendicular to the magnetic field. 2. A device for removing adhered fine particles for removing fine particles adhering to the surface of an object to be cleaned, comprising: a moving means for moving the object to be cleaned parallel to the surface thereof, And a magnetic field generating means for generating a magnetic field perpendicular to the surface thereof.