JP2002086088A - Plasma cleaner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma cleaner free from the problem on a friction produced between a tray and a lower electrode when the tray enters or leaves the chamber. SOLUTION: There is provided a plasma cleaner provided with an airtightly sealable chamber 2, a lower electrode 9 placed in the chamber 2, an upper electrode 10 placed over the lower electrode 9 in the chamber 2, and an electroconductive tray 8 attached to the chamber 2 in such a manner that it can freely and horizontally enter or leave the chamber 2 and coming into contact with the top of the electrode 9 in the state in which it is placed within the chamber 2, wherein the tray 8 moves in the state in which a clearance exists between it and the top of the electrode 9, and it descends just before it is placed in the chamber 2 so as to come into contact with the top of the electrode 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art Conventionally, the surface of a substrate has been cleaned by wet cleaning using chlorofluorocarbon or an organic solvent. However, there are problems in terms of environment and toxicity. The dry cleaning process for cleaning the substrate has been widely performed. Representative examples of such a plasma processing method include a reactive ion etching (RIE) method and a plasma etching (PE) method.

In the RIE method, for example, as shown in FIG.
Lower electrode 2 arranged in a chamber that can be hermetically sealed
01 is connected to the high-frequency power supply 203, the upper electrode 202 disposed above the lower electrode 201 in the chamber is connected to the ground potential, and the chamber is sealed with the substrate A placed on the lower electrode 201. In a vacuum state, a plasma reaction gas (Ar, O _2, etc.) is supplied into the chamber, and high frequency power is supplied to the lower electrode 201.

Then, plasma is generated in the chamber,
Lower electrode 20 in which positive ions in plasma are negatively charged
1, the positive ions collide with the surface of the substrate A to remove impurities on the surface of the substrate A. Such a process is suitable for, for example, a pre-process when performing wire bonding to a substrate.

On the other hand, in the PE method, as shown in FIG. 8, for example, a lower electrode 201 is connected to a ground potential, an upper electrode 202 is connected to a high-frequency power source 203, and a substrate A is mounted on the lower electrode 201. In this state, the chamber is sealed and evacuated, and plasma reaction gas (Ar, O
₂ ) to supply high frequency power to the upper electrode 202.

Then, plasma is generated in the chamber,
Upper electrode 20 in which positive ions in plasma are negatively charged
2, the positive ions hardly collide with the surface of the substrate A, and the radicals in the plasma mainly collide with each other, and the surface of the substrate A is chemically modified. Such a process is suitable for, for example, a pre-process when sealing a component mounted on the surface of the substrate with a resin.

Some of these plasma processing apparatuses have a mechanism for automatically taking a substrate into and out of the chamber. In the conventional mechanism, the top wall of the chamber and the upper part of one of the side walls are arranged. The substrate can be opened and closed, and a substrate is moved into and out of the chamber by a transfer member that moves in and out of the chamber from one side of the chamber over one side wall of the chamber.

In this mechanism, when an unprocessed substrate is loaded into the chamber, the top wall of the chamber and the upper part of one of the side walls are opened, and the substrate is disposed at a substrate transfer position set on one side of the chamber. The unprocessed substrate is transferred onto the lower electrode by the transfer member. Then, after carrying out the plasma processing with the chamber sealed, when unloading the processed substrate, the top wall of the chamber and the upper part of one of the side walls are opened, and the processed substrate on the lower electrode is moved by the transfer member. Is transferred to the substrate transfer position.

In the case of such a mechanism, as shown in FIG. 9, one side wall 301 of the chamber exists between the substrate mounting table 302 arranged at the substrate transfer position and the lower electrode 303. Since the distance L between the portion between the lower electrode 302 and the lower electrode 303 is long and the bottom surface of the substrate A is not supported at this portion, when the substrate A is very thin, as shown in FIG. There is a problem that the substrate A cannot be transferred onto the lower electrode 303 because it is bent by its own weight.

In view of the above problems, as shown in FIG. 10, a tray 402 on which a substrate is placed is mounted in a chamber 401 so as to be able to freely enter and exit in a horizontal direction, and the substrate is transferred on the tray 402 protruding from the chamber 401. Such a mechanism has been devised. In this mechanism, the chamber 40
When loading an unprocessed substrate into the tray 1, a direction (arrow Y direction) orthogonal to the moving direction of the tray 402 (arrow X direction)
The transfer member 403 reciprocatingly transfers the unprocessed substrate A disposed at the substrate transfer position set on one side of the tray 402 onto the tray 402, and thereafter, transfers the unprocessed substrate A to the tray 40.
2 is housed in the chamber 401 and the chamber 401 is sealed. When the plasma processing is completed, the tray 402 projects from the chamber 401, and the processed substrate A on the tray 402 is transferred to the substrate transfer position by the transfer member 403.

In such a mechanism, the substrate mounting table (not shown) at the substrate transfer position can be arranged close to the tray 402. Therefore, even if the substrate is a thin substrate, the leading end portion of the substrate is connected to the substrate mounting table. The substrate on the substrate mounting table can be transferred onto the tray 402 without bending between the trays 402. In order to effectively perform the plasma processing on the substrate, it is preferable that the tray 402 be conductive and be in contact with the top of the lower electrode when housed in the chamber 401.

[0012]

In this case, the tray 40
2 only moves horizontally, the tray 40
2 moves while being in contact with the lower electrode, so that there is a problem that the lower electrode is damaged and fine dust is generated, and a load on an actuator for driving the tray 402 is increased.

An object of the present invention is to provide a plasma cleaning apparatus which solves the above-mentioned problems.

In order to solve the above-mentioned problems, a plasma cleaning apparatus according to the present invention comprises a chamber which can be hermetically sealed, a lower electrode provided in the chamber, An upper electrode disposed above the lower electrode and a conductive tray that is attached to the chamber so as to be able to move in and out of the chamber in a horizontal direction and is in contact with the top of the lower electrode when housed in the chamber. In the plasma cleaning apparatus provided, the tray is moved with a gap between the tray and the top of the lower electrode, and is lowered just before being housed in the chamber so as to contact the top of the lower electrode. It is characterized by having been constituted.

[0014] More specifically, the plasma cleaning apparatus of the present invention comprises a chamber having an opening formed in the front surface, a lower electrode disposed in the chamber, and an upper part of the lower electrode in the chamber. An upper electrode, a lid attached to the chamber so as to approach and separate from the front surface of the chamber, and a front end fixed to an inner surface of the lid, and in a horizontal direction together with the lid. A flexible tray that moves into and out of the chamber, wheels mounted on both sides of the rear end of the tray, guide members provided on both sides of the lower electrode, and guiding the wheels,
A wheel dropper formed at the rear end of each guide member, and when the tray moves, each wheel pushes up the rear end of the tray to move between the tray and the top of the lower electrode. When the tray is housed in the chamber, each wheel enters the wheel dropping portion so that the tray contacts the top of the lower electrode. In this case, since it has a simple structure, it can be manufactured at low cost.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, specific embodiments of the present invention will be described with reference to the drawings. FIG. 1 shows a chamber 2 and a tray 8 of a plasma cleaning apparatus according to an embodiment of the present invention.
FIG. 2 is a longitudinal sectional view of the chamber 2 and the tray 8 in the front-rear direction, showing a state where the tray 8 protrudes from the chamber 2. FIG. 3 is a plan sectional view of the chamber 2 and the tray 8. FIG. 4 shows a state in which the tray 8 is housed in the chamber 2, and FIG. 5 shows a state in which the tray 8 is housed in the chamber 2. FIG. 6 is a plan sectional view of the tray 8, showing a state in which the tray 8 is housed in the chamber 2. FIG. 6 is a perspective view of a lower insulator 11 provided between the tray 8 and the bottom wall of the chamber 2. is there.

In this plasma cleaning apparatus, for example, when a bare chip is directly wire-bonded, the bonding pads of the substrate are dry-cleaned in order to improve the bonding strength between the bonding pads and the bonding wires in bonding. That is, a plasma reaction gas such as argon is filled in a chamber that is a vacuum container,
A high frequency voltage is applied to this to generate plasma, and ions charged in the plasma are accelerated toward the negatively charged bonding pad, and particles on the surface of the bonding pad (in the case of the embodiment, organic substances, oxides, etc.) This is washed by knocking out).

As shown in FIG. 1, the plasma cleaning apparatus 1 includes a chamber 2 in which plasma is generated and the introduced substrate A is cleaned. The chamber 2 has a box-shaped chamber main body 3 having an opening formed on the front surface, and a lid 4 provided to face the front surface of the chamber main body 3. The lid 4 is configured to be able to advance and retreat in the horizontal direction with respect to the chamber main body 3 by lid guides 5 (only one is shown) provided on both sides, and a chamber opening / closing cylinder (air cylinder) 6 provided on a side surface of the chamber main body 3. Of the piston rod 7.

A tray 8 on which two substrates A are placed is mounted inside the lid 4. The tray 8 is made of a conductive material, and moves forward and backward together with the lid 4. When the chamber opening / closing cylinder 6 is driven to move the lid 4 forward, the chamber body 3 is opened and the tray 8 on which the substrate A is placed is pulled out. When the lid 4 is retracted, the tray 8 is moved into the chamber body 3. Pushed and chamber body 3
Is closed. Although not shown, between the chamber body 3 and the lid 4, an O is provided to maintain the airtightness of the chamber 2.
A seal member such as a ring is interposed.

As shown in FIGS. 2 and 3, a rectangular plate-shaped lower electrode 9 disposed below and a rectangular plate-shaped upper electrode 10 disposed above the lower electrode 9 are provided in the chamber 2. I have. The lower electrode 9 is arranged below the tray 8, is attached to the inner surface of the bottom wall of the chamber body 3 via a rectangular plate-shaped lower insulator 11, and is fixed to the outer surface of the bottom wall of the chamber body 3. The connection terminal 12 is electrically connected. On the other hand, the upper electrode 10 is attached to an upper inner surface of the chamber main body 3 via a rectangular plate-shaped holder 13 and is electrically connected to a connection terminal 14 fixed to an outer surface of a top wall of the chamber main body 3.

The connection terminals 12 and 14 are connected to a high-frequency power supply (not shown) and a ground potential via a plurality of vacuum relays (not shown). These vacuum relays are connected to a control device. According to a switching command from the control device, one of the upper electrode 10 and the lower electrode 9 is connected to a high-frequency power source, and the other of the lower electrode 9 and the upper electrode 10 is grounded. Connect to potential.

A gas introduction hole 15 is provided in the top wall of the chamber body 3.
Are formed, and the gas introduction hole 15 is provided in the holder 1.
3, reaches the upper electrode 10, has a larger diameter below the upper electrode 10, and is open to the bottom surface of the upper electrode 10. A plate 16 is fitted into the lower end of the gas introduction hole 15, and a plurality of gas ejection holes 17 penetrating in the thickness direction are formed in the plate 16. Gas introduction hole 1
A gas supply pipe 18 is connected to the upper end of the gas supply pipe 5, and the gas supply pipe 18 supplies an argon gas as a plasma reaction gas and a nitrogen gas for leakage alternately into the chamber 2. (Not shown) is connected.

A gas exhaust hole 19 is formed in the bottom wall of the chamber body 3 so as to face the center of the lower electrode 9, and the gas exhaust hole 19 evacuates the chamber 2. A vacuum suction device (not shown) is connected.
A concave portion 20 is formed on the bottom surface of the lower insulator 11 so as to be aligned with the gas discharge hole 19. The concave portion 20 communicates with a groove 21 formed in a grid pattern over the entire bottom surface of the lower insulator 11. ing. The grooves 21 are open on four sides of the lower insulator 11.

The lower insulator 11 has a concave portion 22 for accommodating the lower electrode 9, and the top surface of the lower electrode 11 accommodated in the concave portion 22 is formed by the concave portion 22 of the lower insulator 11.
Is located slightly above the top surface of the surrounding area. As shown in FIG. 6, the top surfaces of both end portions (guide members) 23 of the lower insulator 11 are formed horizontally from the front end portion to just before the rear end portion, and thereafter inclined rearward and downward. Later, it is formed so as to be horizontal again, whereby a wheel dropping portion 24 is formed at the rear end of both side end portions (guide members) 23.

The tray 8 is formed of a flexible metal plate. As shown in FIG. 4, the front end of the tray 8 has a fixing member 25 so that the bottom surface is flush with the top surface of the lower electrode 9. The cover 4 is fixed to the inner surface of the cover 4. Also, tray 8
Wheels 26 are rotatably mounted on both sides of the rear end of the lower insulator 11. The lower portions of these wheels 26 project downward from the bottom surface of the tray 8, and are attached to the top surface of the side end 23 of the lower insulator 11. In contact. When the tray 8 is housed in the chamber 2, each wheel 26 enters the wheel dropping section 24, and the tray 8 is flat and the bottom surface is in contact with the top surface of the lower electrode 9.

When the tray 8 moves in a direction protruding from the chamber 2, the wheels 26 move out of the wheel dropping section 24 and move forward as shown in FIG. As a result, the wheels 26 push the rear end of the tray 8 upward, so that the tray 8 bends upward with the front end as a fulcrum, and a gap is generated between the bottom surface of the tray 8 and the top surface of the lower electrode 9. When the tray 8 moves in this state, no friction occurs between the tray 8 and the lower electrode 9, so that the tray 8 can be moved with a small force and the load on the chamber opening / closing cylinder 6 can be reduced. Further, the lower electrode 9 is not damaged, and generation of dust can be prevented.

As shown in FIG. 1, the plasma cleaning apparatus includes a substrate transfer mechanism 27. The substrate transfer mechanism 27 moves in a direction (direction indicated by an arrow X ') perpendicular to the moving direction of the tray 8 (the direction of the arrow X'). The transfer member 28 reciprocates in the direction of the arrow Y ′), and transfers the substrate A between the substrate transfer position set on one side of the chamber 2 and the tray 8. .

Next, the operation of the plasma cleaning apparatus of this embodiment will be described. Here, the case where the RIE processing is performed will be described. First, the rod 7 of the chamber opening / closing cylinder 6 advances, and the tray 8 stored in the chamber 2 projects from the chamber 2. At this time, the tray 8 moves with a gap between the tray 8 and the top surface of the lower electrode 9 as shown in FIG. When the tray 8 moves by a predetermined stroke and stops, the substrate transfer mechanism 27 transfers the unprocessed substrate A at the substrate transfer position onto the tray 8.

Next, the rod 7 of the chamber opening / closing cylinder 6 is retracted, and the tray 8 is stored in the chamber 2. At this time, the tray 8 moves horizontally with a gap between the tray 8 and the top surface of the lower electrode 9 immediately before being housed in the chamber 2, and immediately before being housed in the chamber 2,
When the vehicle reaches the inclined surface on the front end side of the wheel dropping portion 24, it descends while moving in the horizontal direction, and each wheel 26
At the same time when the horizontal plane 4 is reached, the tray 8 comes into contact with the top surface of the lower electrode 9 and the lid 4 comes into contact with the front surface of the chamber body 3 to stop the tray 8 (see FIG. 4).

Next, the vacuum suction device is driven to evacuate the chamber 2, and the plasma reaction gas is supplied into the gas introduction hole 15 through the gas introduction pipe 18. The plasma reaction gas supplied to the gas introduction hole 15
The gas is ejected into the chamber 2 through the gas ejection holes 6.
Then, the high-frequency power supply is driven, and high-frequency power is supplied to the lower electrode 9. As a result, plasma is generated in the chamber 2, and positive ions in the plasma are mainly attracted to the negatively charged tray 8, so that the positive ions collide with the surface of the substrate A and scrape impurities on the surface of the substrate A.

The plasma reactant gas ejected into the chamber 2 spreads in the entire circumferential direction after hitting the surface of the substrate A, and flows downward along the side surfaces of the tray 8 and the lower insulator 11, so that the lower insulating gas flows. The gas flows into a groove 21 opened on each side surface of the body 11, and is sucked into a gas exhaust hole 19 through a concave portion 20 formed in the lower insulator 11. When the plasma processing is completed, nitrogen gas is introduced into the chamber 2 through the gas introduction pipe 18, and the plasma reaction gas in the chamber 2 is discharged to the outside through the gas discharge holes 19.

Then, the rod 7 of the chamber opening / closing cylinder 6 advances, the tray 8 projects from the chamber 2, and the processed substrate A on the tray 8 is transferred to the substrate transfer position by the substrate transfer mechanism 27. The next unprocessed substrate A waiting at the substrate transfer position is transported onto the tray 8. Then, the above-described steps are repeated.

The present invention is not limited to the above-described embodiment, and various modifications can be made to the above-described embodiment without departing from the gist of the present invention.

[0033]

As described above, in the plasma cleaning apparatus according to the present invention, the tray moves while leaving a gap between the tray and the top of the lower electrode, and descends immediately before being housed in the chamber. As the tray moves, no friction occurs between the lower electrode and the lower electrode, so that the load on the actuator that drives the tray can be reduced, and Can be prevented from generating fine dust due to scratches.

[Brief description of the drawings]

FIG. 1 is a perspective view of a chamber 2 and a tray 8 of a plasma cleaning apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal cross-sectional view of a chamber 2 and a tray 8 in a front-rear direction, showing a state where the tray 8 protrudes from the chamber 2;

FIG. 3 is a plan sectional view of the chamber 2 and a tray 8, showing a state where the tray 8 protrudes from the chamber 2. FIG.

FIG. 4 is a longitudinal cross-sectional view of the chamber 2 and a tray 8 in the front-rear direction, showing a state where the tray 8 is stored in the chamber 2;

FIG. 5 is a plan sectional view of the chamber 2 and a tray 8, showing a state where the tray 8 is housed in the chamber 2.

FIG. 6 is a perspective view of a lower insulator 11 provided between the tray 8 and a bottom wall of the chamber 2.

FIG. 7 is a diagram illustrating the principle of RIE plasma processing.

FIG. 8 is a diagram for explaining the principle of a PE type plasma process.

FIG. 9 is an explanatory diagram of a problem of the conventional technique.

FIG. 10 is a perspective view of a main part of a conventional plasma processing apparatus.

[Explanation of symbols]

 2 Chamber 4 Lid 8 Tray 9 Lower electrode 10 Upper electrode 23 Side end of lower insulator (guide member) 24 Wheel dropper 26 Wheel

Claims (2)

[Claims] 1. A chamber that can be hermetically sealed, a lower electrode disposed in the chamber, an upper electrode disposed above the lower electrode in the chamber, and a horizontal direction with respect to the chamber. Attached freely,
A plasma cleaning apparatus comprising: a conductive tray in contact with the top of the lower electrode when housed in the chamber; wherein the tray moves with a gap between the tray and the top of the lower electrode. A plasma cleaning apparatus configured to be lowered immediately before being housed in the chamber and to contact the top of the lower electrode. 2. A chamber having an opening formed on a front surface thereof;
A lower electrode disposed in the chamber, an upper electrode disposed above the lower electrode in the chamber, and a lid attached to the chamber so as to approach and separate from a front surface of the chamber. A flexible tray having a front end fixed to the inner surface of the lid, moving in a horizontal direction together with the lid to enter and exit the chamber, wheels attached to both sides of the rear end of the tray, A guide member provided on both sides of the lower electrode, for guiding the wheels, and a wheel dropper formed at a rear end of each guide member, wherein each wheel is provided with a tray when the tray moves. The rear end is pushed up to form a gap between the tray and the top of the lower electrode, and when the tray is stored in the chamber, each wheel enters the wheel dropper. Plasma cleaning apparatus characterized by serial tray is in contact with the top of the lower electrode.