JPH10242097A - Plasma cleaning equipment of substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma cleaning equipment having an inside observing means which can excellently observe the whole in a vacuum chamber at the time of plasma generation, and is not affected by plasma. SOLUTION: In the ceiling face of a lid 12 of a vacuum chamber 13, an aperture 12a is formed, on which a transparent plate 15 is fixed. In the lower part isolated from the transparent plate 5 by a specified interval H, a counter electrode 19 constituted of a mesh plate 19b is arranged. Gas is sent in the vacuum chamber 13, and plasma is generated by applying a high frequency voltage to an electrode 17. Thereby the surface of a substrate 8 is subjected to cleaning. In this case, the state of plasma generation is observed through the transparent plate 15, which is shielded from plasma by the mesh plate 19b and so not damaged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a substrate plasma cleaning apparatus used for cleaning the surface of a substrate or the like.

[0002]

2. Description of the Related Art As a method of mounting a chip, a method of mounting a chip directly on a substrate such as a printed circuit board or a lead frame is known. In this method, after the chip is mounted, wire bonding for connecting the electrode of the chip and the electrode of the substrate with a wire is performed. To perform this wire bonding satisfactorily, it is required that the electrode surface of the substrate to which the wires are connected be clean. Therefore, before the wire bonding step, cleaning for cleaning the electrode surface is performed. In the case of a flip chip, since the bumps are directly bonded to the electrodes of the substrate, the surface of the electrodes of the substrate is also cleaned before bonding the bumps to the electrodes of the substrate.

As a method for cleaning such a substrate, a method using plasma cleaning is known.
According to this method, cleaning is performed by generating plasma in a reduced-pressure atmosphere and causing ions and electrons to collide with the surface of a substrate to be cleaned.

Hereinafter, a conventional substrate plasma cleaning apparatus will be described with reference to the drawings. FIG. 3 is a sectional view of a conventional substrate plasma cleaning apparatus. In FIG. 3, reference numeral 1 denotes a base plate. A lid 2 is mounted on the base plate 1 so as to be opened and closed by opening and closing means (not shown). The base plate 1 and the lid 2 constitute a vacuum chamber 3. A viewport 5 including a glass plate 4 and a pressing member 4a is provided on a side surface of the lid 2. The viewport 5 is for observing the inside of the vacuum chamber 3 from outside. An electrode 7 is mounted on the center of the base 1 via an insulator 6.

[0005] The upper surface of the electrode 7 constitutes the bottom surface of the vacuum chamber 3. The vacuum chamber 3 is connected to an intake / exhaust unit (not shown) and a gas supply unit for generating plasma. A substrate 8 to be cleaned is placed on the upper surface of the electrode 7. A counter electrode 9 is mounted on the ceiling of the lid 2 above the substrate 8, and the counter electrode 9 is electrically grounded. The electrode 7 is connected to a power supply 10.

Hereinafter, the operation of the conventional substrate plasma cleaning apparatus will be described. In FIG. 3, a substrate 8 is placed on an electrode 7. In this state, the lid 2 is closed by opening / closing means (not shown), and the vacuum chamber 3 is sealed. Next, the inside of the vacuum chamber 3 is depressurized by an exhaust means (not shown), and then a plasma generating gas such as an argon gas is introduced into the vacuum chamber 3. Next, when a high frequency voltage is applied to the electrode 7 by the power supply 10, plasma is generated between the electrode 7 and the counter electrode 9. As shown by broken arrows in FIG. 3, the surface of the substrate 8 is cleaned by collision of ions and electrons with the surface of the substrate 8.

[0007]

The cleaning of the substrate 8 by the plasma cleaning apparatus is based on the precondition that plasma is normally generated inside the vacuum chamber 3. Therefore, a viewport 5 for observing the state inside the vacuum chamber 3 is provided to confirm the state of generation of the plasma.

However, the view port 5 for observing the inside of the conventional plasma cleaning apparatus is provided on the side surface of the vacuum chamber 3 as shown in FIG. 3, and is viewable due to its location and size restrictions. There is a problem that the visual field range is limited.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plasma cleaning apparatus for a substrate provided with an internal observation means capable of satisfactorily observing the inside of a vacuum chamber.

[0010]

According to the present invention, there is provided a plasma cleaning apparatus for a substrate, comprising: a base plate; a vacuum chamber provided on the base plate and serving as a ground electrode; and an opening / closing means for opening and closing the cover. A plasma cleaning apparatus for a substrate, comprising: an electrode provided at a lower portion of a vacuum chamber; suction / exhaust means for reducing the pressure in the vacuum chamber; and plasma supply gas supply means for supplying a plasma generation gas into the vacuum chamber. A transparent plate is mounted on the ceiling of the lid, and a metal mesh plate for shielding the transparent plate is provided below the transparent plate, and the mesh plate conducts with the lid to form a ground electrode. I tried to double.

[0011]

According to the present invention having the above structure, a wide area inside the vacuum chamber can be visually recognized from the ceiling surface of the lid through the transparent plate and the mesh plate. Further, since the transparent plate is shielded by the mesh plate, it is not adversely affected by the plasma in the vacuum chamber.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention, and FIG. 2 is a sectional view of the plasma cleaning apparatus for the same substrate.

First, the overall structure of a plasma cleaning apparatus for a substrate will be described with reference to FIG. In FIG. 1, reference numeral 11 denotes a base plate, which is mounted on a frame 11b.
A substantially box-shaped lid 12 is provided on the base plate 11, and the base plate 11 and the lid 12 constitute a vacuum chamber 13. The lid 12 is mounted on a lifter 14 serving as an opening / closing unit.
The lifter 14 is provided with a motor 14a. By driving the motor 14a, the lid 12 moves up and down, and the vacuum chamber 13 is opened and closed.

A transparent plate 15 is mounted on the ceiling surface of the lid 12 by a pressing member 15a. A gasket 21 is mounted on the upper surface of the base plate 11, and a contact portion between the upper surface of the base plate 11 and the lid 12 is vacuum-sealed. An electrode 17 is mounted at the center of the base plate 11. Electrode 17
A substrate 8 to be cleaned is placed on the upper surface of the substrate.

An intake / exhaust port 22 and a plasma gas supply port 23 are opened in the base 11 plate of the vacuum chamber 13. The intake / exhaust port 22 is connected to an intake / exhaust unit 24 via a pipe 22a, and performs intake / exhaust for reducing the pressure in the vacuum chamber 13 and breaking the vacuum. The plasma gas supply port 23 is connected to a gas supply means 25 for plasma generation such as argon gas through a pipe 23a,
A gas for generating a plasma is supplied into 3.

On the upper surfaces of the base plate 11 and the electrodes 17, there are provided transfer grooves 26a and 26b for continuous substrates. A transfer arm 27 for the substrate 8 is disposed in front of the base plate 11. The transfer arm 27 is mounted on a slider 28. The slider 28 is connected to a belt 29. Therefore, when the belt 29 is driven by a driving unit (not shown), the transport arm 27 moves in the horizontal direction.
The base end of the transfer arm 27 is pivotally mounted on a pin 30 provided on a slider 28, and is rotated about the pin 30 by driving means (not shown). The tip of the transfer arm 27 is bent downward to form a claw 27a. When the transfer arm 27 is moved horizontally with the claw 27a lowered, the claw 27a pushes the end of the substrate 8 on the transfer grooves 26a and 26b. Thereby, the substrate 8 is carried into the vacuum chamber 13 and sent out of the vacuum chamber 13.

Next, the structure of the vacuum chamber 13 will be described with reference to FIG. In FIG. 2, a through hole 11 a is provided in the center of the base plate 11. An electrode 17 is inserted into the through-hole 11a from the lower surface of the base 11 plate.
Is mounted on the lower surface of the base 11 plate via the. The contact surfaces of the base plate 11, the insulator 16, and the electrode 17 are sealed by a seal 31. The upper surface of the electrode 17 also serves as a transfer groove 26 for transferring the substrate 8, and the substrate 8 is placed in the transfer groove 26. The electrode 17 is connected to a power supply 20, and a high-frequency voltage is applied when necessary.

An opening 12a is provided in the ceiling of the lid 12. The opening 12a is made as large as possible within an allowable range in size. A transparent plate 15 is attached to the opening 12a by a pressing member 15a. The contact surface between the transparent plate 15 and the lid 12 is sealed by a seal 32. Below the transparent plate 15 at a predetermined distance H,
The counter electrode 19 is mounted according to the shape of the opening 12a. The counter electrode 19 has a structure in which a mesh plate 19b is fixed to a metal frame 19a. The mesh plate 19b is provided with a large number of holes in a thin metal plate and can be sufficiently seen through. The counter electrode 19 is electrically grounded via the lid 12, and functions as a ground electrode.

The plasma cleaning apparatus for a substrate has the above-described configuration, and its operation will be described below. In FIG. 1, a substrate 8 is placed on an electrode 17.
In this state, the lid 12 is closed by the lifter 14, and the vacuum chamber 13 is sealed. Next, the intake / exhaust means 24 is driven, and the pressure inside the vacuum chamber 13 is reduced. Next, the plasma generating gas supply means 25 is driven, and a plasma generating gas such as an argon gas is introduced into the vacuum chamber 13. Next, when a high-frequency voltage is applied to the electrode 17 by the power supply 20 shown in FIG. 2, a plasma is generated between the electrode 17 and the counter electrode 19. 2, the surface of the substrate 8 is cleaned by the collision of ions and electrons with the surface of the substrate 8, as indicated by the downward dashed arrows.

During operation of the plasma cleaning device,
As described above, it is necessary to observe the state of generation of plasma in the vacuum chamber 13. As shown in FIG. 2, in the plasma cleaning apparatus for a substrate, an opening 12 a in which a transparent plate 15 is mounted is provided on the ceiling of the lid 12. For this reason, the plasma generation state of the entire vacuum chamber 13 can be visually recognized from above through the transparent plate 15 and the see-through mesh plate 19b.

Further, a mesh plate 1 serving as a counter electrode is provided.
9b is mounted with an interval H between it and the transparent plate 15 provided thereon. For this reason, the plasma generated between the electrode 17 and the mesh plate 19b as the counter electrode 19 is shielded by the mesh plate 19b and does not reach the transparent plate 15. In addition, scattered matter (see the upward dashed arrow in FIG. 3) generated by the collision of ions and electrons with the surface of the substrate 8 is also applied to the mesh plate 1.
9b. Therefore, the transparent plate 15 is not adversely affected by the plasma, such as damage caused by the collision of the plasma and the scattered objects, and thermal influence.

[0022]

According to the present invention, over a wide area inside the vacuum chamber through the transparent plate and the mesh plate,
The state of plasma generation can be observed. Further, since the transparent plate is shielded by the mesh plate, the plasma in the vacuum chamber does not reach the transparent plate. Therefore, the transparent plate is less damaged, and the transparent plate can be used for a long time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a substrate plasma cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a plasma cleaning apparatus for a substrate according to an embodiment of the present invention.

FIG. 3 is a sectional view of a conventional substrate plasma cleaning apparatus.

DESCRIPTION OF SYMBOLS 11 Base 12 Lid 13 Vacuum chamber 14 Lifter (opening / closing means) 15 Transparent plate 17 Electrode 19 Counter electrode (ground electrode) 19b Mesh plate 24 Intake / exhaust means 25 Plasma gas generation means

Claims (1)

[Claims] A vacuum chamber comprising a base plate and a lid provided on the base plate and serving also as a ground electrode;
Opening and closing means for opening and closing the lid, an electrode provided at the lower part of the vacuum chamber, and a suction and exhaust means for reducing the pressure in the vacuum chamber,
What is claimed is: 1. A plasma cleaning apparatus for a substrate, comprising: a plasma generating gas supply means for supplying a plasma generating gas into a vacuum chamber, wherein a transparent plate is mounted on a ceiling of said lid, and said transparent plate is provided below said transparent plate. A plasma cleaning apparatus for a substrate, comprising: a metal mesh plate that shields a transparent plate; and the mesh plate conducts with the lid and also serves as a ground electrode.