JPH1012594A - Plasma treatment device with slot antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To plasma treatment device, allowing easy control of plasma uniformity in a microwave plasma treatment device. SOLUTION: In a plasma treatment device utilizing a microwave, a coaxial type hollow resonator 8 is used to provided a slot antenna tilted at an angle neither parallel nor vertical to the direction of a surface current flowing on the wall surface, arranged with a slot antenna 9. A microwave of a TEM mode is easily excited inside the coaxial type hollow resonator 8, and a ratio in the microwave of the TEM mode is changed, so as to control uniformity of generated microwave plasma.

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 having a slot antenna, and more particularly to a plasma processing apparatus having a slot antenna suitable for etching and film-forming a sample such as a semiconductor element substrate using microwave plasma. The present invention relates to a plasma processing apparatus having the same.

[0002]

2. Description of the Related Art A conventional device using a slot antenna uses a cylindrical cavity resonator as described in Japanese Patent Application Laid-Open No. 6-48287, for example, and is perpendicular to the surface current flowing through the bottom of the cavity resonator. The slot antenna was arranged in the direction of. Thus, the microwaves in the same mode as the microwave mode in the cavity resonator are radiated by the slot antenna to generate plasma.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a plasma processing apparatus having a slot antenna which can easily control the uniformity of plasma.

[0004]

In order to achieve the above object, a TEM mode microwave is excited in a coaxial cavity resonator, and a slot antenna provided at the bottom of the cavity resonator is provided at the bottom of the cavity resonator. They are arranged in a ring at an angle that is neither parallel nor perpendicular to the direction of the flowing surface current.

A surface current flows radially, that is, in the radial direction on the bottom wall surface of the cavity resonator in the TEM mode. If the slot antenna is arranged so as to intersect at a certain angle that is neither parallel nor perpendicular to the direction of the surface current, and is arranged in a ring shape, radial and circumferential microwave electric fields are radiated from the slot antenna. That is, microwaves in which the TE _on mode and the TM _om mode (m and n are positive integers) are mixed are emitted. Therefore, by changing the angle at which the slot antenna and the surface current intersect, T
Since E (is m, n a positive integer) _on mode and TM _om modes can change the ratio of, it can be easily controlled uniformity of the generated microwave plasma.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. FIG. 1 shows a magnetic field microwave dry etching apparatus which is an embodiment of the plasma processing apparatus of the present invention. The inside of the processing chamber 1 partitioned by the container 1a, the discharge tube 1b and the quartz window 2 is evacuated (not shown).
After the pressure is reduced, an etching gas is introduced into the processing chamber 1 by a gas supply device (not shown) and adjusted to a desired pressure. Further, the processing chamber 1 is in a magnetic field region generated by the coil 3. In this case, the microwave of 2.45 GHz oscillated from the magnetron 4 propagates through the waveguide 5, the coaxial waveguide converter 6, the matching chamber 7, and is introduced into the coaxial cavity resonator 8. . A slot antenna 9 is provided on the bottom surface of the coaxial cavity resonator 8. The microwave radiated from the slot antenna 9 transmits through the quartz window 2, forms a specific mode while transmitting through the quartz window 2, and then enters the processing chamber 1. The quartz window 2 is provided with a microwave locally radiated from the slot antenna 9.
Has a thickness necessary to form a specific mode while passing through the inside. In order to form a microwave of a specific mode, the thickness of the quartz window 2 is not necessarily increased because it is sufficient that the processing chamber has a propagation space of a necessary distance until the microwave is introduced into the processing chamber. It is not necessary to use only means. The wafer 11 placed on the sample stage 10 is etched by the plasma generated by the microwave. To control the etching shape of the wafer 11, a high frequency power supply 12 is connected to the sample stage 10 via a matching device so that a high frequency voltage can be applied.

In this embodiment, the use of the coaxial cavity resonator 8 has an effect that the TEM mode can be easily excited in the cavity resonator.

As shown in FIG. 2, a radial surface current flows radially from the center of the TEM mode coaxial cavity resonator 8 as shown in FIG. As shown in FIG. 4, when the relative direction of the surface current is arranged at right angles to the slot antenna 9 longitudinally since the electric field in the radial direction is generated in the slot antenna 9, it is to the processing chamber 1, TM ₀₁ mode Microwaves are emitted. Although illustration is omitted, when the slot antenna 9 is arranged in parallel with the surface current, the electric field intensity generated in the slot antenna 9 is weak, and the microwave is hardly radiated to the processing chamber 1. As shown in FIG. 2, when the slot antenna 9 is arranged at an angle that is neither perpendicular nor parallel to the surface current, a radial electric field Er and a circumferential electric field Eθ are formed in the slot antenna 9. Antenna 9
And the surface current at a rate corresponding to the angle. Therefore, a microwave in which the TM ₀₁ mode and the TE ₀₁ mode are mixed is radiated to the processing chamber 1. TE ₀₁ mode microwave, for most field intensity at about 1/2 of the portion of the waveguide diameter increases, the processing chamber 1 the ring diameter φc of placing the slot antenna 9 in a ring shape as shown in FIG. 2 About 1 / of inner diameter
When the 2 efficiently, microwaves TE ₀₁ mode is emitted. A 45-degree angle between the slot antenna 9 and the surface current, have a about 1/2 and the electric field intensity distribution of the TM ₀₁ mode and the TE ₀₁ mode are both axisymmetric to the processing chamber 1 of the inner diameter of the processing chamber 1 the φc As described above, by supplying a microwave mixed with these modes to the processing chamber 1, there is an effect that plasma having an axially symmetric distribution can be easily generated. The generated plasma has a large loss on the outer peripheral wall surface of the processing chamber 1, but has a small loss on the central axis. Therefore, by providing the ring-shaped plasma generation region, uniform plasma over a wide range can be easily generated. By placing the mixed microwave of TM ₀₁ mode and the TE ₀₁ mode, can be provided with a plasma generation region in a ring shape, and by changing the ratio of TM ₀₁ mode and the TE ₀₁ mode, the ring-shaped plasma generation The ring diameter of the region can be changed, and the plasma uniformity can be controlled. As described above, TM ₀₁ mode and TE ₀₁
The mode ratio can be changed by changing the angle at which the slot antenna 9 intersects with the surface current, or by changing the shape of the slot antenna 9 or the position of the slot antenna 9.

A second embodiment of the present invention will be described with reference to FIG. In this embodiment, a high frequency power supply 13 is used instead of the magnetron 4. The high frequency power supply 13 is connected to the matching unit 14 and the matching room 7 using a coaxial cable. In this embodiment, there is an effect that the device can be downsized. The frequency of the high-frequency power supply 13 is not limited to 2.45 GHz, but may be, for example, 500 MHz, 100 MHz, 13.5.
2.45 GHz such as 6 MHz, 2 MHz, 800 kHz
Other frequencies may be used. As the frequency is lower, there is an effect that a high-output power supply can be easily manufactured at lower cost.

In each of the above embodiments, a magnetic field microwave dry etching apparatus has been described. However, the present invention can be applied to a magnetic field microwave CVD apparatus. A plasma processing apparatus such as a CVD apparatus or an ashing apparatus has a similar effect.

[0011]

According to the present invention, a TEM mode is easily generated in a cavity using a coaxial cavity resonator, and the surface current flowing on the wall surface of the cavity into which microwaves are introduced and the surface current are measured. By changing the angle of intersection with the slot antenna installed on the wall, the ratio of various microwave modes radiated from the slot antenna can be changed, so that the uniformity of the generated microwave plasma can be easily controlled. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a magnetic field microwave dry etching apparatus according to a first embodiment of the present invention.

FIG. 2 is a plan view showing the shape of the slot antenna in FIG.

FIG. 3 is a vertical sectional view showing a magnetic field microwave dry etching apparatus according to a second embodiment of the present invention.

FIG. 4 is a plan view showing a conventional slot antenna shape.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Processing chamber, 1a ... Container, 1b ... Discharge tube, 2 ... Quartz window,
3 ... coil, 4 ... magnetron, 5 ... waveguide, 6 ... coaxial waveguide converter, 7 ... matching chamber, 8 ... coaxial cavity resonator, 9
... Slot antenna, 10 ... Sample table, 11 ... Wafer, 1
2: High frequency power supply, 13: High frequency power supply, 14: Matching device.

Claims (4)

[Claims] 1. A processing chamber to which an evacuation device is connected and whose inside can be decompressed, a gas supply device into the processing chamber, and plasma generated inside the processing chamber using microwaves radiated from a slot antenna. A plasma generating apparatus comprising: a plasma generating means having a microwave coaxial cavity resonator; and a slot antenna provided at the bottom of the coaxial cavity resonator. A plasma processing apparatus having: 2. A plasma processing apparatus according to claim 1, wherein a slot antenna is provided at an angle that is not parallel or perpendicular to a surface current flowing through the bottom of the TEM mode coaxial cavity resonator. A plasma processing apparatus having an antenna. 3. The plasma processing apparatus according to claim 1, wherein the TE _om mode and the TM _on mode (m,
A plasma processing apparatus having a slot antenna, characterized in that plasma is generated by a microwave mixed with (n is a positive integer). 4. The plasma processing apparatus according to claim 2, wherein the angle of the slot antenna is 45 °.