JP3536585B2 - Workpiece plasma processing apparatus and plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a workpiece plasma processing apparatus and a workpiece plasma processing method for performing plasma processing on the surface of a workpiece.

[0002]

2. Description of the Related Art A plasma processing method is known as a method for performing various processes such as removal of foreign substances on a surface of a work such as a substrate and formation of a surface film. In the plasma processing, a processing chamber in a vacuum chamber is depressurized, and a high-frequency voltage is applied to one of two electrodes facing each other under the depressurized atmosphere to generate plasma. Particles of this substance are scattered by colliding electrons or ions with the substance that forms the surface film, by removing foreign substances on the surface or activating the surface by colliding ions or ions with the surface of the object to be treated. Is attached to the surface of the object to be treated.

[0003] Since plasma processing is performed under reduced pressure, a workpiece to be processed is usually housed in a vacuum chamber.
Vacuum suction is performed in the vacuum chamber by a vacuum suction means such as a vacuum pump, and after the plasma processing is completed, air is introduced into the vacuum chamber to return to normal pressure.

[0004]

It takes a required decompression time to vacuum-evacuate the inside of a vacuum chamber of a certain volume and to reach a required degree of vacuum in the processing chamber. This decompression time is generally about several tens of seconds. The time of several tens of seconds is considerably long as the tact time of the manufacturing process and the mounting process of the electronic component, and it has been required to reduce the decompression time in order to increase the productivity. However, in the conventional plasma processing apparatus, it is necessary to use a large-capacity vacuum pump in order to reduce the decompression time, and this causes a problem that the apparatus becomes large and the cost increases.

In general, when the vacuum pump is operated, oil used for lubricating the vacuum pump is mixed as fine particles into the exhaust gas and discharged as an oil mist. The amount of the oil mist is proportional to the volume of the vacuum chamber to be vacuum-sucked. When the large-volume vacuum chamber is frequently opened and closed, the air around the plasma processing apparatus is exhausted from the vacuum pump. The degree of contamination by oil mist will increase. Particularly in a production line for electronic components that require high cleanliness, air pollution by the oil mist is not allowed. Therefore, in a plasma processing apparatus having a large processing capacity, it is necessary to provide a large outdoor exhaust system around the plasma processing apparatus. There was a problem.

Further, in the case of performing the plasma processing, the optimum electrode distance is fixed in the conventional plasma processing apparatus despite the fact that the optimum inter-electrode distance varies depending on the type of the work. However, there is a problem that the plasma processing is not performed.

Accordingly, the present invention provides a vacuum chamber having a large volume, a vacuum pump of a small capacity can be used to vacuum the vacuum to a required degree of vacuum in a short time, the amount of oil mist generated can be reduced, and the type of workpiece can be reduced. It is an object of the present invention to provide a plasma processing apparatus and a plasma processing method in which optimum processing conditions can be set for each case.

[0008]

According to a first aspect of the present invention, there is provided a plasma processing apparatus comprising: a lower electrode disposed in a vacuum chamber; a high frequency power supply for applying a high frequency voltage to the lower electrode; and a ground provided above the lower electrode. A movable partition including electrodes, vacuum suction means for vacuum suctioning the processing chamber of the vacuum chamber, a plasma gas supply unit for supplying a plasma generation gas to the processing chamber, and an atmosphere opening device for opening the processing chamber to the atmosphere; The moving means for moving the movable partition and the processing chamber are changed so as to reduce the volume, and vacuum suction is continued by the vacuum suction means.
And a controller for controlling the moving means of the movable partition in order to increase the degree of vacuum by increasing the volume of the processing chamber while appropriately setting the inter-electrode distance according to the work.

[0009]

According to a second aspect of the present invention, in the plasma processing method, the workpiece is housed in the processing chamber of the vacuum chamber, and the movable partition including the ground electrode provided in the vacuum chamber is moved by the moving means controlled by the control unit. A process of vacuum-suctioning the processing chamber with vacuum suction means in a state where the volume of the processing chamber is reduced, and continuing vacuum suction by the vacuum suction means.
And setting the distance between the electrodes corresponding to the workpiece with increasing the degree of vacuum and while increasing the volume of the processing chamber by moving the movable partition wall by the moving means while, for generating plasma in the processing chamber from the plasma gas supply unit Supplying the gas, applying a high-frequency voltage to the lower electrode to generate plasma in the processing chamber to perform plasma processing on the surface of the work, and sending air to the processing chamber to return the processing chamber to normal pressure. And opening the vacuum chamber to take out the work.

[0011]

According to the first and second aspects of the present invention, suction at the time of vacuum suction is performed by changing the volume of a processing chamber formed in a vacuum chamber by moving a movable partition. Since the volume can be reduced, the required degree of vacuum can be reached in a short time even with a small-capacity vacuum pump, and the amount of oil mist generated by the vacuum pump can be reduced.

[0012]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side sectional view of a plasma processing apparatus according to an embodiment of the present invention, and FIGS. 2, 3, 4, 5, 6, 7, and 8 are partial sectional views of the plasma processing apparatus. .

First, the overall structure of the plasma processing apparatus will be described with reference to FIG. In FIG. 1, a box-shaped lid 2 is arranged on a base member 1. The base member 1 and the lid 2 constitute a vacuum chamber 3. A cylinder 4 is mounted on an end of the base member 1, and a rod 5
A block 6 is attached to the tip of the. Block 6
Is integrally connected to the lid 2. Therefore, when the rod 5 of the cylinder 4 protrudes and retracts, the lid 2 moves up and down on the base member 1, and the vacuum chamber 3 opens and closes.

An opening is provided at the center of the base member 1, and a lower electrode 7 is mounted through the opening.
An insulating plate 8 is provided between the lower electrode 7 and the lower surface of the base member 1. The lower electrode 7 is mounted on the lower surface of the base member 1 by bolts 11 with the insulating plate 8 interposed therebetween. A seal 12 is provided between the lower surface of the base member 1 and the insulating plate 8 and between the insulating plate 8 and the lower electrode 7. The electrode 7 is pressed against the lower surface of the base member 1, and the pressing force crushes the seal 12 to seal the seal surface.

On the upper surface of the lower electrode 7, a work 13 to be subjected to plasma processing is placed. The lower electrode 7 is electrically connected to a high-frequency voltage generator 14 which is a high-frequency power supply. The high-frequency voltage generator 14 applies a high-frequency voltage to the lower electrode 7.

Openings 19 and 20 are provided on the upper surface of the lid 2. The opening 19 is a ventilation hole that allows the inside of the lid 2 to communicate with the outside. A bearing block 21 is mounted on the upper surface of the opening 20. A bearing 22 is mounted inside the bearing block 21, and a nut 23 is inserted through the bearing 22. Nut 23 has feed screw 2
4 is screwed in, and a plate 25 is connected to the lower end of the feed screw 24. The lower end of a cylindrical bellows 26 for airtightness is attached to the peripheral edge of the plate 25, and the upper end of the bellows 26 is airtightly connected to the ceiling surface of the lid 2.

A pulley 27 is connected to an upper end of the nut 23. A motor 28 is provided on the upper surface of the lid 2, and a pulley 29 is mounted on a rotating shaft of the motor 28. A belt 30 is adjusted between the pulley 27 and the pulley 29. Therefore, by driving the motor 28, the nut 23 rotates, and the plate 25 connected to the lower end of the feed screw 24 moves up and down inside the lid 2. That is, the plate 25 and the bellows 26 are movable partitions that move while maintaining the airtightness in the space in the vacuum chamber 3, and the nut 23, the feed screw 24, and the motor 28 move the plate 25 in the vertical direction. It is a means. A space surrounded by the base member 1, the lid 2, the plate 25, and the bellows 26 forms a processing chamber P. Therefore, when the plate 25 moves up and down, the volume of the processing chamber P decreases, and when it rises, the volume increases. Further, the plate 25 is electrically grounded to the grounding portion 40 and serves as a ground electrode facing the lower electrode 7.

At the right end of the base member 1, a through hole 31 is provided. A pipe 32 is connected to the through hole 31. A vacuum pump 3 as a vacuum suction means is provided in the pipe 32.
5. The atmosphere opening device 36 and the vacuum gauge 37 are connected. A pipe 33 is connected to the left end of the base member 1, and a plasma gas supply unit 34 is connected to the pipe 33. The control unit 38 receives a signal from the vacuum gauge 37,
Motor 28, high-frequency voltage generator 14, air release device 3
6. The operation of each part of the vacuum pump 35 and the plasma generating gas supply unit 34 is controlled.

The plasma processing apparatus for a workpiece has the above-described configuration, and its operation will be described below with reference to the drawings. 2 to 7 show a series of operations in the order of operation. First, FIG. 2 shows the rod 5 of the cylinder 4 (see FIG. 1).
Are projected, the lid 2 is raised, and the vacuum chamber 3 is open. In this state, the work 13 is placed on the lower electrode 7. At this time, the plate 25 is at the lowered position.

Next, as shown in FIG. 3, the lid 2 is lowered and the vacuum chamber 3 is closed. Thereafter, vacuum suction in the vacuum chamber 3 is performed via the pipe 32 (see arrow a). In this state, the base member 1 and the lid 2
And a processing chamber P formed by a plate 25 serving as a movable partition
Is that the volume is reduced because the plate 25 is in the lowered position as described above (1/1 when compared to when the plate 25 is raised).
About 50). Therefore, the decompression time until the required degree of vacuum is reached is greatly reduced.

Next, as shown in FIG. 4, while continuing the vacuum suction, the motor 28 is driven to move the plate 25, which is a movable partition, upward (see the arrow b) to increase the volume of the processing chamber P. . Thereby, the degree of vacuum in the processing chamber P is further increased, and the inter-electrode distance H is set according to the work 13 to be subjected to the plasma processing.

Next, as shown in FIG. 5, the plasma generating gas supply unit 34 is driven to introduce a plasma generating gas such as argon gas from the pipe 33 into the processing chamber (arrow c).
reference). Next, the high-frequency voltage generator 14 is driven to apply a high-frequency voltage to the lower electrode 7. Thereby, plasma is generated in the space between the lower electrode 7 and the plate 25 functioning as a ground electrode (see the hatched portion in FIG. 5). In this case, the distance H between the lower electrode 7 and the plate 25 is set to a distance according to the target work 13, so that optimum plasma conditions according to the work 13 are realized.

Here, the relationship between the distance H between the electrodes and the optimum plasma conditions will be described with reference to FIG. FIG. 8 (a)
8 shows the state of plasma in the processing chamber when the work 13 is small and the distance H1 between the electrodes is small.
(B) shows the state in the processing chamber when the workpiece is large and the distance H2 between the electrodes is large. FIG. 8 (a),
In (b), the density of the hatching provided between the lower electrode 7 and the ground electrode 25 indicates the density of the plasma, and the graph f indicates the degree to which the surface of the processing target is shaved by electrons or ions generated by the plasma. 3 shows the distribution of the indicated etching rate.

As shown in FIG. 8A, the distance between the electrodes H1
When is small, the portion where the plasma density is high is concentrated in the center of the processing chamber, and the etching rate has a large value in the center of the processing chamber and decreases in the periphery. That is, when it is desired to process a small work 13 in a short time, the efficient plasma processing can be performed by positioning the work 13 near the center of the processing chamber and reducing the distance H1 between the electrodes.

On the other hand, as shown in FIG.
When the inter-electrode distance H2 is large, the plasma density in the processing chamber is low but uniform throughout the processing chamber, and the etching rate also shows a uniform distribution. That is, when a plurality of large works 13 or a plurality of small works are arranged and processed, uniform plasma processing can be performed over a wide range by increasing the distance H between the electrodes.

As described above, the optimum plasma processing conditions can be set by appropriately setting the inter-electrode distance H according to the difference in the size of the work 13 or the processing target portion.

Next, when the plasma processing of the work 13 is completed, the motor 28 is driven to lower the plate 25 (see arrow d) as shown in FIG. 6, and the volume of the processing chamber is reduced again. Next, the atmosphere release device 36 is driven to introduce the atmosphere into the processing chamber P through the pipe 32. Again,
Since the volume of the processing chamber P is reduced, the time required for introducing the atmosphere into the processing chamber P and returning the processing chamber P to normal pressure is greatly reduced.

Next, as shown in FIG. 7, the cylinder 4 is driven to raise the lid 2 to open the vacuum chamber 3. Next, the work 13 having been subjected to the plasma processing is taken out of the vacuum chamber 3, and one cycle of the plasma processing is completed.

[0030] The present invention has been not limited to the above embodiment, although the above SL embodiment For example uses a combination of plate 25 and the bellows 26 as a movable partition wall, short while maintaining the airtightness of the movable partition wall What is necessary is just to make the structure which can change the volume of the processing chamber of the vacuum chamber.

[0031]

According to the present invention, the suction volume at the time of vacuum suction can be reduced by changing the volume of the processing chamber formed in the vacuum chamber by moving the movable partition serving as the ground electrode. Therefore, even if the vacuum pump has a small capacity, the required degree of vacuum can be reached in a very short time. Therefore, the takt time can be shortened, and the amount of oil mist generated by the vacuum pump can be reduced, so that the surrounding air is not polluted and equipment costs for large-scale outdoor exhaust equipment are reduced. it can. In addition, the movable electrode is moved by the moving means so that the distance between the electrodes is reduced.
By changing the separation, the optimal plasma for the workpiece
Processing conditions can be set for efficient and
High quality plasma processing is realized.

[0032]

[Brief description of the drawings]

FIG. 1 is a side sectional view of a plasma processing apparatus according to an embodiment of the present invention.

FIG. 2 is a partial cross-sectional view of a plasma processing apparatus according to an embodiment of the present invention.

FIG. 3 is a partial sectional view of the plasma processing apparatus according to one embodiment of the present invention;

FIG. 4 is a partial cross-sectional view of the plasma processing apparatus according to one embodiment of the present invention;

FIG. 5 is a partial sectional view of the plasma processing apparatus according to one embodiment of the present invention;

FIG. 6 is a partial sectional view of the plasma processing apparatus according to one embodiment of the present invention;

FIG. 7 is a partial cross-sectional view of a plasma processing apparatus according to an embodiment of the present invention.

8A is a partial cross-sectional view of a plasma processing apparatus according to one embodiment of the present invention; FIG. 8B is a partial cross-sectional view of a plasma processing apparatus according to one embodiment of the present invention;

[Explanation of symbols]

1 Base member 2 Lid 3 vacuum chamber 4 cylinder 7 Lower electrode 13 Work 14 High frequency voltage generator 24 Lead screw 25 plates 26 Bellows 28 motor 34 Plasma gas supply unit 35 vacuum pump 36 Atmospheric release device 37 vacuum gauge 38 Control unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ identification code FI H01L 21/3065 H01L 21/302 C (58) Field surveyed (Int.Cl. ⁷ , DB name) H05H 1/46 C23C 14 / 54 C23C 16/50 C23F 4/00 H01L 21/203 H01L 21/3065

Claims (2)

(57) [Claims] A lower electrode disposed in a vacuum chamber, a high-frequency power supply for applying a high-frequency voltage to the lower electrode, a movable partition including a ground electrode provided above the lower electrode, and a processing chamber of the vacuum chamber. A vacuum suction means for vacuum suction, a plasma gas supply unit for supplying a plasma generation gas to the processing chamber, an atmosphere opening device for opening the processing chamber to the atmosphere, a moving means for moving the movable partition, and a volume of the processing chamber. And the vacuum suction is continued by the vacuum suction means.
And a control unit for controlling the moving means of the movable partition in order to increase the degree of vacuum by increasing the volume of the processing chamber while appropriately setting the inter-electrode distance according to the work. Features Plasma processing equipment for workpieces. 2. A work is stored in a processing chamber of a vacuum chamber.
And a step of vacuum suction by vacuum suction means the process chamber in a state of reduced volume of the processing chamber is moved by the moving means controlled by the movable partition wall control unit including a ground electrode provided in the vacuum chamber, the vacuum Vacuum suction by suction means
And setting the distance between the electrodes corresponding to the workpiece with increasing the degree of vacuum while increasing the volume of the processing chamber by moving the movable partition wall by while continuing and the moving means, the processing chamber from the plasma gas supply unit A step of supplying a plasma generating gas; a step of applying a high-frequency voltage to the lower electrode to generate plasma in the processing chamber to perform a plasma treatment on the surface of the work; Returning to pressure and opening the vacuum chamber to remove the workpiece.