JP3122430B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus and a plasma processing method.

[0002]

2. Description of the Related Art Generally, in a semiconductor product manufacturing process, a semiconductor wafer is subjected to a CVD process, an etching process, a sputtering process, and the like. A plasma processing device is used as an apparatus for performing such various processes. May be FIG. 8 is a cross-sectional view showing an example of this type of conventional magnetron type plasma processing apparatus. For example, two flat electrodes are placed in a processing vessel 2 made of aluminum or the like.
That is, the upper electrode 4 and the lower electrode 6 are arranged in parallel, and the lower electrode 4 is used as a mounting table to support a semiconductor wafer W as an object to be processed. Then, for example, 1
A 3.56 MHz high frequency power supply 8 is applied to form an electric field in the processing space, and the processing gas is supplied from the processing gas source 12 via the mass flow controller 14 and the upper electrode 4 to the container 2.
The plasma is introduced into the processing space. Further, a permanent magnet 16 is disposed above the container 2 so as to apply a magnetic field to the processing space to efficiently generate plasma.

[0003]

The above-described electric field introduction type plasma processing apparatus has the following improvements. In other words, when plasma is generated in the processing space and the processing proceeds and the plasma density reaches a certain level, for example, a region with many ions, that is, a sheath is generated immediately above the lower electrode, and this exerts a shielding function against an electric field to be introduced. In some cases, the density could not be further increased, and as a result, sufficient throughput could not be obtained.

In this electric field introduction type device,
Since the same high-frequency power supply for forming plasma and the same high-frequency power supply for performing etching use the same power supply, for example, it is possible to independently control the power during plasma formation and the offset voltage (bias voltage) during etching. Not. The present invention has been devised in view of the above problems and effectively solving them. An object of the present invention is to provide a plasma processing apparatus and a plasma processing method that can efficiently generate plasma by forming an alternating magnetic field and an alternating electric field with a high-frequency current.

[0005]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a processing container in which an object to be processed can be placed, and a mounting table for mounting the object in the processing container. A first high-frequency power supply for applying high-frequency power to the mounting table, a conductive member provided outside the processing container, and a second high-frequency power supply for applying high-frequency power to the conductive member to generate plasma. In the plasma processing apparatus having the high-frequency power source of claim 2, the conductive member is disposed on the upper surface side of the ceiling of the processing container, and a plurality of the conductive members are formed so as to extend from substantially the center to the periphery of the ceiling. And the plurality of conductive members are electrically coupled at the central portion to electrically connect the second high frequency power supply to the central portion.

[0006]

Since the present invention is constructed as described above, an alternating magnetic field is generated in the processing container by passing a current through a plurality of conductive members, and a direction perpendicular to the alternating magnetic field, that is, in a radial direction of the container. An alternating electric field is generated. The action of the alternating magnetic field and the alternating electric field makes it possible to increase the plasma generation efficiency.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a plasma processing apparatus and a plasma processing method according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a partially cutaway perspective view showing an embodiment of a plasma processing apparatus according to the present invention, FIG. 2 is an explanatory view for explaining movement of electrons in the apparatus shown in FIG. 1, and FIG. 3 is an apparatus shown in FIG. FIG. In this embodiment, a case where the plasma processing apparatus is applied to an etching apparatus will be described.

As shown, the plasma processing apparatus 18
Has a processing container 20 whose ceiling is formed flat and the whole is shaped into a cylindrical body, and the inside of the container is configured as a processing space S. At the lower part in the container, a mounting table 22 formed in a disk shape by, for example, aluminum or the like is installed insulated from the container side, and an object to be processed, for example, a semiconductor wafer W is mounted on the upper surface of the mounting table 22. It is configured so that it can be placed. The mounting table 22 is connected to a high-frequency power source 26 for etching, for example, at 13.56 MHz as a first high-frequency power source via a first matching circuit 24. It draws enough power for use.

Further, a gas introduction path 28 for supplying a processing gas for etching such as CHF ₃ or CF _{4 to the} inside of the processing vessel 20 is connected to the side wall of the processing vessel 20, and this introduction path 28 is shown in the middle. Not connected to a gas source via a mass flow controller. Further, a gas exhaust path 30 for evacuating the inside of the processing container is connected to the side wall of the container bottom, and a vacuum exhaust system having a vacuum pump and the like (not shown) is connected to the exhaust path 30.

On the other hand, the processing vessel 20 constructed as described above
On the outer surface of the flat ceiling portion 32, there is provided a high-frequency antenna means 34 which is a feature of the present invention. More specifically, the antenna means 34 includes a plurality of antennas 34 extending radially outward from the center portion 36 of the ceiling portion 32 in the radial direction.
For example, a 13.56 MHz plasma is provided as a second high-frequency power source through a second matching circuit 41 that performs impedance matching using a lead wire 40. Connected to a high-frequency power supply 42 for use.

Each of the conductive members 38 has a cross-sectional area of a predetermined size or more or a width of a predetermined size or more in the case of a thin film in order to flow a current of a predetermined value or more. Each conductive member 3
8 are connected in common by a ring-shaped conductor 44, and the conductor 44 is connected to the second
Is connected to the high frequency power source for plasma 42 via the matching circuit 41 of FIG. Accordingly, the plasma high-frequency power supply 42 flows from the center point 36 toward the conductor 44 at the peripheral portion of the conductive member 38, or conversely, flows from the conductor 44 at the peripheral portion toward the center point 36. It is configured to flow an alternating high-frequency current.

In the illustrated example, the lead wire 46 is drawn from one point of the conductor 44 which connects the ends of the conductive members 38 in common. However, in order to make the high-frequency current flowing through each conductive member 38 uniform, The lead wires 46 may be drawn out from many points evenly distributed in the circumferential direction of the ring-shaped conductor 44. By passing the alternating high-frequency current through each conductive member 38 in this manner, alternating magnetic fields 48A and 48B concentrically extending in the circumferential direction are generated in the processing space S in the container 20,
At the same time, alternating electric fields 50A and 50B oscillating in a direction orthogonal to the alternating magnetic fields 48A and 48B, that is, in a radial direction from the center of the container are generated.

On the other hand, a magnet means 52 composed of, for example, a ring-shaped electromagnet is provided at a portion outside the processing vessel 20 and corresponding to the processing space S, and the alternating magnetic field 48A, 48B and an alternating electric field of 50A,
Direction orthogonal to each of 50B. That is, in the illustrated example, it is configured such that a downward static magnetic field 54 can be formed. The static magnetic field 54 may be formed in the upward direction. Therefore, a Lorentz force acts on the plasma generating electrons E located in the processing space S in the circumferential direction, and concentrically drifts as shown in FIG. Is confined. If the static magnetic field 54 can be formed as described above, a permanent magnet may be used instead of the electromagnet. Further, a vacuum chamber (not shown), for example, a load lock chamber, for loading and unloading the wafer into and from the processing container 20 is connected to the processing container 20.

Next, the operation of the embodiment constructed as described above will be described. First, the wafer W is placed on the mounting table 22.
And the inside of the processing container 20 is changed from 1 mTorr to 3 mTorr, for example.
The processing gas is introduced from the gas introduction path 28 in a state where the vacuum state is set to the range of 00 mTorr. When the high-frequency power supply 42 for plasma and the high-frequency power supply 26 for etching are driven, the conductive members 3 radially provided on the ceiling 32 are driven.
8, a high-frequency current flows, thereby generating concentric circumferentially alternating magnetic fields 48A and 48B in the processing space S as shown in FIGS. An alternating electric field 50A in the radial direction about the axis,
50B occurs. Here, the electrons E in the processing space S tend to accelerate at high speed in the directions of the electric fields 50A and 50B, but in this embodiment, the magnet means 5 provided outside the container is used.
Since the static magnetic field 54 is applied in the vertical direction by 2, the electrons E are concentrically drifted by the Lorentz force acting on the electrons E, and the electrons E are efficiently confined in the static magnetic field 54. The electrons confined and drifting here collide with neutral atoms of the processing gas to generate plasma, and thus plasma can be formed efficiently.

In this case, the strength of the static magnetic field 54 is preferably as small as possible within a range where the drift electrons E do not collide with the inner wall of the container, and is preferably 1 K gauss or less, for example. In addition, since the high-frequency power supply for plasma 42 is provided separately from the high-frequency power supply 26 for etching, it is possible to independently control the amount of supplied power, for example, to independently control the offset voltage or the like during etching. Can be. Each high-frequency power supply is not limited to 13.56 MHz, but may have any frequency as long as it is, for example, 100 KHz or more.

Further, unlike the conventional electric field introduction type apparatus, the introduction of the electric field by the sheath is not obstructed, and the plasma density can be greatly improved. In the above embodiment, the ends of the conductive members 38 are commonly connected by a ring-shaped conductor 44, but the present invention is not limited to this. For example, as shown in FIG. The auxiliary lead wires 56 may be pulled out from the ends in a state of being floated from the ceiling 32, and the auxiliary lead wires 56 may be commonly connected to the lead wires 46. Further, as shown in FIG. 5, each of the conductive members 38 may be branched in the middle toward the outside in the radial direction to have a substantially radial structure.

Further, the entire surface of the ceiling may be covered with a sheet-like thin film made of a conductive material, and the periphery may be folded back so as to rise above the ceiling and coupled to a lead wire connected to a high-frequency power supply. Good. Also in this case, the other leads are connected to the conductive member at the center of the ceiling. In the above embodiment, when the mounting table for mounting and holding the wafer is disposed above the processing space, the conductive member 38 for generating plasma may be formed on the outer surface of the bottom of the container.

Further, in the above embodiment, the ceiling 3
2 has been described as being flat and provided with a conductive member in this portion, but the present invention is not limited to this. For example, as shown in FIG. It can also be applied to containers. That is, when the processing container 20 is formed in a tube shape in this manner, the conductive member 38 for plasma generation is not provided on the ceiling, but a large number of members are provided in the height direction over the entire outer periphery of the container side wall. The conductive member 38 is formed. The conductive member 38
May be formed of, for example, one conductive plate so as to cover the entire side wall of the container. Then, the upper end of each conductive member 38 is commonly connected by a ring-shaped upper connecting member 58, and one lead wire 46 from the high frequency power supply 42 is connected to this. Further, the lower ends of the conductive members 38 are commonly connected by a ring-shaped lower connecting member 60, and another lead wire 40 from the high frequency power supply 42 is connected thereto.

A ring-shaped magnet means 52 made of, for example, an electromagnet is provided on the side of the processing vessel 20 so as to surround the processing vessel 20 as in the embodiment shown in FIG.
The vertical static magnetic field 54 is formed in the processing space in the container 20. The entire container is hermetically mounted and held on a base 64 made of, for example, stainless steel via a seal member 62.

In this embodiment, a high-frequency current is applied to a plurality of conductive members 38 surrounding the side wall of the container, so that alternating magnetic fields 48A, 48B concentrically extending in the circumferential direction are formed in the processing space S in the same manner as shown in FIG. Occurs, and at the same time, an alternating electric field oscillating in the radial direction of the container is also generated, thereby accelerating the electrons. The accelerated electrons drift concentrically due to the action of the static magnetic field 54 in the vertical direction, and confinement is performed well as in the previous embodiment, so that the plasma generation efficiency can be increased. Although not shown, it is a matter of course that a mounting table connected to a high frequency power supply for etching is provided in the container.

In the example of the device shown in FIG. 6, the upper end and the lower end of each conductive member 38 are commonly connected by a ring-shaped connecting member. However, the present invention is not limited to this. For example, FIG. As shown, the upper end and the lower end of the adjacent conductive members 38 are sequentially connected in series except for one point by a connection lead wire 66, and the plasma is applied from the upper end and the lower end of the remaining one conductive member. Lead wires 40 and 46 extending to the high-frequency power supply 42 for use. The connection lead wire 66 is of course floated away from the container side wall. In the case of this embodiment, the same operation and effect as the device shown in FIG. 6 can be exhibited. In the above embodiment, the case where the present invention is applied to a plasma etching apparatus has been described. However, the present invention is not limited to this. For example, any apparatus using plasma such as a plasma CVD apparatus and a plasma LCD apparatus can be used. It can also be applied to things.

[0022]

As described above, according to the plasma processing apparatus of the present invention, the following excellent effects can be obtained. Since a concentric alternating magnetic field is formed by the high-frequency current to induce a radially alternating electric field in the radial direction to generate plasma, the plasma generation efficiency can be greatly improved. Further, unlike the electric field introduction type device, the plasma density can be greatly improved, so that the throughput can be improved. When the present invention is applied to an etching apparatus, the power of plasma and the power of etching can be controlled independently.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view showing one embodiment of a plasma processing apparatus according to the present invention.

FIG. 2 is an explanatory diagram for explaining movement of electrons in the device shown in FIG.

FIG. 3 is a schematic sectional view of the apparatus shown in FIG.

FIG. 4 is a schematic perspective view showing a modification of the conductive member used in the processing apparatus shown in FIG.

FIG. 5 is a schematic plan view showing another modification of the conductive member used in the processing apparatus shown in FIG.

FIG. 6 is a schematic configuration diagram showing another embodiment of the plasma processing apparatus of the present invention.

FIG. 7 is a schematic configuration diagram showing still another embodiment of the plasma processing apparatus of the present invention.

FIG. 8 is a schematic sectional view showing an example of a conventional plasma processing apparatus.

DESCRIPTION OF SYMBOLS 18 Plasma processing apparatus 20 Processing vessel 22 Mounting table 26 High frequency power supply for etching 34 High frequency antenna means 38 Conductive member 42 High frequency power supply for plasma 48A, 48B Alternating magnetic field 50A, 50B Alternating electric field 52 Magnet means 54 Static magnetic field E electron S processing space W semiconductor wafer (workpiece)

Claims (9)

(57) [Claims] 1. A processing container in which an object to be processed can be placed, a mounting table for mounting the object in the processing container, and a first high-frequency power supply for applying high-frequency power to the mounting table And a conductive member provided outside the processing container, and a plasma processing apparatus having a second high-frequency power supply that applies high-frequency power to the conductive member to generate plasma, wherein the conductive member includes: A plurality of the conductive members are disposed on the upper surface side of the ceiling of the processing container and extend from a substantially central portion of the ceiling to a peripheral portion thereof, and the plurality of conductive members are electrically connected at the central portion. Wherein the second high frequency power supply is electrically connected to the central portion. 2. The plasma processing apparatus according to claim 1, wherein the plurality of conductive members are arranged radially. 3. The plasma according to claim 1, wherein the conductive member has a predetermined cross-sectional area or a predetermined width or more for passing a predetermined current or more. Processing equipment. 4. The plasma according to claim 1, wherein the plurality of conductive members are configured to branch off radially outward of the ceiling partway. Processing equipment. 5. A tubular processing container in which a processing object can be arranged, a mounting table for mounting the processing object in the processing container, and a first table for applying high-frequency power to the mounting table.
A high-frequency power supply, a conductive member provided outside the processing container, and a second high-frequency power supply that applies high-frequency power to the conductive member to generate plasma. A plurality of members are arranged on a side wall of the processing container, and are formed in plural numbers so as to extend in a longitudinal direction of the processing container. A plasma processing apparatus characterized in that a plasma is applied. 6. The plasma processing apparatus according to claim 1, wherein the first and second high-frequency power sources have a frequency of 100 KHz or more. 7. The first high frequency power supply is connected to the mounting table via a first matching circuit, and the second high frequency power supply is connected to the second high frequency power supply.
The high-frequency power supply is connected to the conductive member via a second matching circuit, and the first and second high-frequency power supplies are individually and independently controllable. Item 7. The plasma processing apparatus according to any one of Items 1 to 6. 8. The plasma processing apparatus according to claim 1, wherein:
8. The plasma processing apparatus according to claim 1, wherein the apparatus is any one of a D apparatus, a plasma LCD apparatus, and a plasma etching apparatus. 9. A step of mounting a target object on a mounting table in a processing container and introducing a processing gas with a predetermined vacuum state in the processing container, a high-frequency power supply for plasma generation and a high-frequency power for etching A step of driving a power supply, and applying a high-frequency power to a plurality of conductive members disposed on the upper surface side of the ceiling portion of the processing container to flow a high-frequency current alternately between a substantially central portion and a peripheral portion of the ceiling portion And a plasma processing method, wherein the object to be processed is processed by plasma generated in the step.