JPH10106796A - Plasma treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment device with high surface uniformity of the plasma treatment by giving a concentric circle-shaped electric field with almost equal electric field intensity to the inside of a treatment container. SOLUTION: Microwaves generated in a microwave generator 60 are introduced into a plane antenna member 56 through a wave guide 62, then introduced into a treatment container 16 for plasma-treating a material. A microwave introducing port 58 extending in the central direction is formed in the antenna member 56, arranged on a concentric circle, branched wave guides 68A-68D branched from the wave guide 62 are individually connected to the microwave introducing port 58, and a concentric circle-shaped electric field is formed inside the treatment container 16. By producing almost concentric circle-shaped electric field inside the treatment container, the surface uniformity of plasma density is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus in which energy for generating plasma is supplied from the antenna surface by microwaves to generate plasma.

[0002]

2. Description of the Related Art In recent years, a plasma processing apparatus has been used for processing such as film formation, etching, ashing, and the like in a semiconductor product manufacturing process in accordance with high density and high miniaturization of a semiconductor product. , 0.1 to several tens mTorr
A microwave plasma apparatus that generates high-density plasma by combining a microwave and a magnetic field from a ring-shaped coil is used because a plasma can be stably generated even in a high vacuum state having a relatively low pressure of about r. There is a tendency.

Conventionally, as this kind of microwave plasma apparatus, an apparatus as disclosed in Japanese Patent Application Laid-Open No. HEI 3-17273 is known. In this device, a waveguide for introducing microwaves is connected to a plasma generation chamber having a magnetic field forming means, and the microwaves introduced from the waveguides cause electron cyclotron resonance to generate high-density plasma. It is supposed to. FIG. 9 is a schematic configuration diagram showing an example of a conventional plasma processing apparatus of this type, in which a processing vessel 2
A microwave introduction window 4 is provided in the ceiling of the microwave oven, and the microwave generated by the microwave generator 6 is transmitted to, for example, a rectangular waveguide 8.
And, it is guided to the microwave introduction window 4 through the conical waveguide 10 and introduced into the processing vessel 2. The microwave introduced into the processing container 2 is combined with a horizontal magnetic field generated by a magnet 12 provided outside the upper portion of the processing container 2 and an ECR (Electron Cyclot).
ron Resonance), and a high-density plasma is generated.

[0004]

By the way, in the above-mentioned device example, the microwave oscillating in the rectangular waveguide 8 in the TE10 mode is transmitted through the conical waveguide 10 to the TE1.
Since the mode is converted into one mode and introduced into the processing chamber, for example, when looking at a certain cross section on the semiconductor wafer, the electric field density at the center is high, and the electric field density gradually decreases toward the periphery. In this state, the film thickness is also formed substantially in proportion to the density, which causes a problem that the in-plane uniformity of the sputtering rate and the film forming rate is deteriorated. In particular, as the wafer size increases from 8 inches to 12 inches, it becomes more difficult to increase the uniformity of the plasma density, and it is strongly desired to solve the above problems.

In order to solve such a problem, a plurality of independent microwave generators are provided as shown in, for example, Japanese Patent Application Laid-Open No. 2-170530, and microwaves from these generators are separately introduced into a processing vessel. However, in this case, due to the fact that the phases of the microwaves from the respective microwave generators are not aligned with each other, the plasma density is not so much given that a plurality of microwave generators are provided. In addition, the in-plane uniformity of the film thickness cannot be increased, and the cost of the apparatus is inevitably increased due to the plurality of microwave generators.
The present invention has been devised in view of the above problems and effectively solving them. It is an object of the present invention to provide a plasma processing apparatus in which a substantially concentric electric field having a uniform electric field intensity is provided in a processing container, thereby improving the in-plane uniformity of the plasma processing.

[0006]

According to the present invention, in order to solve the above-mentioned problems, a microwave generated by a microwave generator is guided to a planar antenna member through a waveguide, and the object to be processed is thereby obtained. In a plasma processing apparatus for introducing microwaves into a processing vessel for performing plasma processing, microwave introduction ports extending in the center direction are formed in the planar antenna member and arranged concentrically, and the microwave introduction ports are connected to the respective microwave introduction ports. The branch waveguides branched from the waveguides are individually connected to form a concentric electric field in the processing container.

[0007] Thereby, the microwave generated from one microwave generator is branched into a plurality of pieces by a branch waveguide on the way, guided to the corresponding microwave introduction ports, and introduced into the processing vessel. You. Here, since each microwave introduction port is formed so as to extend in the center direction of the planar antenna member and is arranged on a concentric circle, a substantially concentric electric field is generated in the processing container, and a substantially uniform electric field is generated in the plane direction. It is possible to form a distribution. Therefore, the plasma density in the in-plane direction can be made uniform, so that
It is possible to improve the in-plane uniformity of the plasma processing.
Here, by providing the position of the microwave introduction port so that the position can be adjusted in the radial direction of the planar antenna member, it is possible to have a certain degree of distribution in the plasma density according to the type of plasma processing. It is possible to cope with various plasma processes. Also, outside the processing vessel,
By providing a magnet for ECR, it becomes possible to generate electron cyclotron resonance in the processing chamber to improve the plasma density.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG.
FIG. 2 is a configuration diagram illustrating a plasma processing apparatus according to the present invention, FIG. 2 is a perspective view illustrating a junction state between a branch waveguide and a planar antenna member, and FIG. 3 is a plan view illustrating a planar antenna member.

In this embodiment, a case where the plasma processing apparatus is applied to a plasma etching apparatus will be described. As shown in the figure, the plasma etching apparatus 14 as a plasma processing apparatus has, for example, a side wall and a bottom portion formed of a conductor such as aluminum, and is formed into a cylindrical shape as a whole and the upper portion is reduced in diameter into a stepped shape. It has a processing vessel 16 and the inside is configured as a sealed processing space S. The upper part of the processing space S is formed as a plasma generation space S1.

In the processing container 16, a mounting table 18 on which, for example, a semiconductor wafer W as an object to be processed is mounted is accommodated. The mounting table 18 is formed in a substantially columnar shape with a central portion made of, for example, anodized aluminum or the like, and the lower portion thereof is supported by a supporting table 20 also formed in a columnar shape by aluminum or the like. In addition, the support base 20 is installed on the bottom of the processing container 16 via an insulating material 22.

On the upper surface of the mounting table 18, an electrostatic chuck or a clamping mechanism (not shown) for holding the wafer by suction is provided. The mounting table 18 is connected to a matching box 26 via a power supply line 24. And for example 13.56 MH
z is connected to a bias high frequency power supply 28. A cooling jacket 3 for flowing cooling water or the like for cooling a wafer during plasma processing is provided on a support 20 for supporting the mounting table 18.
0 is provided. A processing gas supply nozzle 32 made of, for example, a quartz pipe for introducing an etching gas into the container, for example, is provided in a side wall of the processing container 16 and defining a processing space S. The mass flow controller 36 and the on-off valve 3
8 is connected to a processing gas source 40. Etching gas as a processing gas is CF ₃ , CHF ₃ , CF
₄ , C ₄ F ₈ gas or the like can be used as a single gas or a mixed gas of these gases and hydrogen gas. Further, a gas nozzle 42 made of quartz for supplying an inert gas such as argon as a plasma gas is provided so as to face the plasma generation space S1.
The r gas is supplied here.

Then, outside the step portion of the processing container 16,
A ring-shaped magnet 44 for ECR is provided, and a magnetic field for ECR generation is applied to the plasma generation space S1. A gate valve 46 is provided on the outer periphery of the side wall of the container to open and close when a wafer is loaded and unloaded from the inside of the container. An exhaust port 48 connected to a vacuum pump (not shown) is provided at the bottom of the container so that the inside of the processing container 16 can be evacuated to a predetermined pressure as needed.

On the other hand, in the ceiling portion of the processing container 16, an opening 5 having a size substantially equal to or slightly larger than the diameter of the object to be processed W for introducing microwaves into the container is provided.
0 is formed, and O
A microwave transmission window 54 made of, for example, quartz is hermetically provided via a seal member 52 such as a ring.

On the upper surface side of the transmission window 54, a disc-shaped planar antenna member 56 which is a feature of the present invention is installed. The antenna member 56 is made of a conductive material such as copper or aluminum. As shown in FIGS. 2 and 3, the antenna member 56 has a plurality of slits extending in the radial direction, and four slits in the illustrated example. A long and narrow microwave introduction port 58 is formed. These four microwave introduction ports 58 are arranged on concentric circles and are point-symmetric with respect to the center. Here, the antenna member 56
The distance between the transmission window 54 and the transmission window 54 is preferably set to a length approximately equal to the guide wavelength of the microwave. On the other hand, a microwave generator 60 for supplying a microwave to the microwave inlet 58 generates a microwave of, for example, 2.45 GHz. From now on, the microwave is initially transmitted through a rectangular waveguide 62. Is transmitted, and the transmission form is converted by the converter 64 on the way, and as shown in FIG.
Is transmitted to the antenna member 56 by the coaxial waveguide 68 having

The coaxial waveguide 68 is branched on the way into four branch waveguides 68A to 68D. The tip of each of the branch waveguides 68A to 68D is connected to the four micro waveguides provided on the antenna member 56. It is connected so as to cover the wave inlet 58. The coaxial line 66 is also branched into four, and each of the branched coaxial lines 66A to 66D is connected to the corresponding branch waveguide 6.
8A to 68D, and connected to the antenna member 56. Thus, the microwave generator 60
The microwaves generated at are generated through the rectangular waveguide 62, the coaxial waveguide 68, and the branch waveguides 68A to 68D, and are introduced into the inside of the processing chamber 16 from the respective slit-like microwave introduction ports 58. ing. The microwave vibration mode at the time of the introduction forms a substantially concentric electric field similar to the TE01 mode, and the center portion of each of the microwave introduction ports 58 and the center point O1 of the antenna member 56 is also formed. By adjusting the distance L1 between them, a considerably strong electric field is generated.

Further, as shown in FIG. 2, the distances from the branch point O2 of the branch waveguide 68 to the corresponding microwave inlets 58 through the respective branch waveguides 68A to 68D are set to be the same. And each microwave inlet 5
The phase of the microwave introduced from 8 is set to be in phase with high accuracy. Here, when the diameter of the semiconductor wafer W is 12 inches (about 30 cm), the diameter of the planar antenna member 56 is about 20 to 30 cm as shown in FIG.
The width L2 and length L3 of the slit-like microwave introduction port 58 are set to about 2 to 10 mm and about 40 to 80 mm, respectively. Further, the length L4 of the branch waveguide is set to, for example, about 100 mm, but these numerical values are merely examples, and may be variously changed in accordance with the microwave excitation state and the like. Of course.

Next, the operation of the present embodiment configured as described above will be described. First, the semiconductor wafer W is accommodated in the processing chamber 16 by the transfer arm via the gate valve 46, and the lifter pins (not shown) are moved up and down to place the wafer W on the mounting surface on the upper surface of the mounting table 18. I do.
Then, the inside of the processing container 16 is maintained at a predetermined process pressure, for example, within a range of 0.1 to several tens mTorr, and an etching gas such as CF _{4 is} supplied from the processing gas supply nozzle 30 while controlling the flow rate. Ar gas is supplied from the gas nozzle 42 as a plasma gas. In some cases, the Ar gas is not supplied. At the same time microwave generator 6
Microwaves from 0 to the rectangular waveguide 62 and the coaxial waveguide 6
8 and to the antenna member 56 via the branch waveguides 68A to 68D to generate a plasma generation space S1 and a processing space S1.
Then, an electric field is formed, thereby generating a plasma and performing an etching process.

Here, the microwave of, for example, 2.45 GHz generated by the microwave generator 60 propagates in the rectangular waveguide 62 in the TE10 mode, and is converted into the coaxial mode by the converter 64. Then, the microwave propagated in the coaxial waveguide 68 is divided into four branch waveguides 6 at a branch point O2.
8A to 68D and propagate therethrough, and from each of the slit-like microwave introduction ports 58, the plasma generation space S1
Side, and the magnetic field applied by the magnet 12 causes electron cyclotron resonance. here,
As shown in FIG. 4, the microwave introduction port 58 is formed in an elongated slit shape in the radial direction of the disk-shaped antenna member 56, and is arranged on a concentric circle centered on the center point O1 of the antenna member 58. Therefore, a mode-excitation mode similar to the TE01 mode is generated, and a substantially concentric intersecting electric field generated in the circumferential direction of the antenna member 58 is generated. And
Since the distance from the branch point O2 (see FIG. 2) of the coaxial waveguide 68 to each of the microwave introduction ports 58 is set to be the same, the phases of the microwaves introduced from each of the microwave introduction ports 58 are uniform and in-phase. This makes it possible to generate a substantially uniform electric field in the circumferential direction.

In this case, the central portion of the antenna member 56 in which the electric field strength tends to decrease has an appropriate distance L1 (see FIG. 3) between the center point O1 and each microwave introduction port 58. An electric field can be prevented from dropping. FIG. 5 is a graph showing the intensity distribution of the electric field on the semiconductor wafer, wherein curve A shows the electric field curve of the conventional device, and curve B shows the electric field curve of the device of the present invention. Curve A of the conventional apparatus shows that the electric field intensity decreases from the central portion of the wafer to the peripheral portion. In particular, in the case of a 12-inch wafer having a large wafer size, there is a large difference in the plasma processing between the central portion and the peripheral portion. Will occur. On the other hand, in the case of the curve B according to the present invention, although the electric field intensity slightly decreases at the central portion of the wafer, the electric field intensity does not decrease much at the peripheral portion of the wafer. It is also found that the plasma processing can be performed substantially uniformly over the surface.

As described above, since a high-density plasma can be formed substantially uniformly in the in-plane direction of the wafer, plasma processing, here, uniform etching processing can be performed in the plane. Also, when performing plasma sputtering film formation, uniform film formation can be similarly performed over the surface. In the case of the above embodiment, four slit-like microwave introduction ports are formed in the planar antenna member 56. However, as long as a substantially concentric electric field can be formed, the present invention is not limited to the above numerical values. As shown in FIG. 6, three microwave inlets 58 may be provided on concentric circles at equal intervals of 120 degrees, or five or more microwave inlets may be provided at equal intervals.

In the above embodiment, the mounting position of each microwave inlet 58 is fixed, but depending on the type of process, there may be a case where it is desired to have a slight distribution in the plasma density. In order to cope with such a case, the mounting position of each microwave introduction port 58 may be configured to be movable in the radial direction of the antenna member. 7 and 8 are partial enlarged views showing such a configuration. FIG. 7A is a partially enlarged view of a planar antenna member to which a branch waveguide, for example, 68A is connected. A rectangular auxiliary inlet 70, which is considerably large in the longitudinal direction, is formed. Then, as shown in FIG. 7 (B), a slide plate 72 made of, for example, a copper plate, which is configured to sufficiently cover the auxiliary introduction port 70 and have a certain length in its length direction, is prepared.
This slide plate 72 has a slit-like microwave introduction port 5.
8 is formed in advance. Then, as shown in FIG. 8, the slide plate 72 is superimposed on the auxiliary introduction port 70 and provided so as to be slidable in the radial direction of the antenna member 56 as indicated by an arrow 74.

By providing the mounting position of the microwave introduction port 58 in the radial direction of the antenna member 56 as described above, the amount of drop of the electric field at the central portion of the wafer of the curve B shown in FIG. A desired plasma distribution state corresponding to the type of plasma processing can be obtained. In the above-described embodiment, the case where the antenna member is provided outside the processing container is described as an example. However, the antenna member may be coated with quartz or the like and provided inside the processing container. Although the plasma etching process has been described as an example here, it is needless to say that the present invention can be applied to a plasma film forming process, a plasma sputtering process, a plasma ashing process, and the like. Further, the object to be processed is not limited to a semiconductor wafer, and may be applied to an LCD substrate, a glass substrate, and the like.

[0023]

As described above, according to the plasma processing apparatus of the present invention, the following excellent operational effects can be exhibited. By introducing microwaves having the same phase from a plurality of microwave inlets provided in the flat plate antenna member, a substantially concentric electric field can be formed in the processing container, and the plasma density can be made uniform over a large area. it can. Therefore, the in-plane uniformity of the plasma processing can be improved. In addition, by providing the microwave introduction port so that the position can be adjusted in the radial direction, a desired plasma density distribution state can be obtained in accordance with the type of plasma processing.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a plasma processing apparatus according to the present invention.

FIG. 2 is a perspective view showing a joint state between a branch waveguide and a planar antenna member.

FIG. 3 is a plan view showing a planar antenna member.

FIG. 4 is a diagram showing a state of an electric field at a certain moment formed by a planar antenna member.

FIG. 5 is a graph showing a state of distribution of an electric field above a semiconductor wafer.

FIG. 6 is a plan view showing a planar antenna member when three microwave introduction ports are provided.

FIG. 7 is a diagram showing a configuration for adjusting the position of a microwave introduction port.

FIG. 8 is a view showing a state when the members shown in FIG. 7 are combined.

FIG. 9 is a schematic configuration diagram illustrating an example of a conventional plasma processing apparatus.

[Explanation of symbols]

 Reference Signs List 14 plasma processing apparatus 16 processing container 18 mounting table 44 magnet for ECR 54 microwave transmission window 56 planar antenna member 58 microwave introduction port 60 microwave generator 62 rectangular waveguide 66, 66A to 66D coaxial line 68 coaxial waveguide 68A to 68D Branch waveguide 70 Auxiliary inlet 72 Slide plate W Semiconductor wafer (workpiece)

──────────────────────────────────────────────────の Continued on front page (51) Int.Cl. ⁶ Identification code FI C23F 4/00 C23F 4/00 G H01L 21/203 H01L 21/203 S 21/205 21/205 21/3065 21/302 B

Claims (4)

[Claims] In a plasma processing apparatus, a microwave generated by a microwave generator is guided to a planar antenna member through a waveguide, and the microwave is introduced into a processing container for performing a plasma processing on an object to be processed. A microwave introduction port extending in the center direction is formed in the planar antenna member, and the microwave introduction ports are arranged concentrically. Branch waveguides branched from the waveguides are individually connected to the respective microwave introduction ports to perform the processing. A plasma processing apparatus, wherein a concentric electric field is formed in a container. 2. The plasma processing apparatus according to claim 1, wherein the microwave introduction port is provided so as to be adjustable in a radial direction of the antenna member. 3. The plasma processing apparatus according to claim 1, wherein the length from the branch point of the branch waveguide to each of the microwave introduction ports is set to be the same. 4. The plasma processing apparatus according to claim 1, wherein an ECR magnet is provided outside the processing container.