JP2871266B2 - Plasma equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a plasma device,
In particular, the present invention relates to an apparatus structure for facilitating the start of discharge of an ECR plasma apparatus.

[0002]

2. Description of the Related Art In an ECR plasma apparatus, microwaves (usually using an industrial frequency of 2.45 GHz) generated by a magnetron oscillation tube or the like are introduced into a plasma generation chamber using a waveguide, and formed in the plasma generation chamber. External magnetic field (875 when the microwave frequency is 2.45 GHz)
G) is a plasma device that continuously accelerates electrons by electron cyclotron resonance (ECR) in G) and maintains plasma by the impact ionization action (α action) of high-energy electrons generated thereby. Electrons until the electron to continue to accelerate while swirling motion strikes the plasma generating chamber wall surface high probability of collision with the gas molecules, difficult 10 ^-3 to 10 ^-1 Pa in the plasma apparatus of a parallel plate electrode type Plasma is generated stably even at a relatively low gas pressure. Also,
Since electrons can be continuously accelerated over one or more cycles of the microwave, plasma is efficiently generated even at a low microwave electric field strength. Further features are that the sheath voltage is relatively small, damage to the substrate due to ion irradiation is small, there is no need to insert an electrode into the plasma generation chamber, and there is no contamination by electrode metal. Utilizing these features, E
The CR plasma apparatus is applied to a dry etching apparatus capable of performing anisotropic processing with low damage, a plasma CVD apparatus having low damage and good coverage, and the like.

FIG. 2 shows the structure of a conventional ECR plasma apparatus. The external magnetic field 15 required for ECR is formed by a permanent magnet or an electromagnetic coil. However, the electromagnetic coil 6 is frequently used because of its advantage that the magnetic field shape and the magnetic field strength can be freely changed. When the shape of the magnetic field is a divergent magnetic field, positive ions are extracted by an electric field generated by electron drift. In this case, the substrate support 7 is usually placed at a position away from the ECR point 16. In some cases, the shape of the magnetic field may be substantially a parallel magnetic field, and only the acceleration of ions by the sheath voltage generated on the surface of the substrate 8 may be used without using the extraction of positive ions by the divergent magnetic field. In this case, in order to minimize the acceleration of ions due to the magnetic field gradient, the ECR point 16 where plasma is most easily generated is disposed immediately above the substrate 8. As described above, the relative position of the ECR point 16 with respect to the substrate support 7 is finely adjusted according to the purpose.

In FIG. 2, 1 is a microwave oscillation tube, 2 is a waveguide, 3 is a tapered waveguide, 4 is a microwave introduction window, 5 is a plasma generation chamber, 6 is a coil, 9 is a microwave, 10 is a standing wave.

[0005]

SUMMARY OF THE INVENTION As described above, ECR
Once the plasma device starts discharging, microwave power is efficiently converted to electron energy at the ECR point, and plasma is continuously generated even at low gas pressure and low electric field strength. However, depending on conditions, such as when the gas pressure is particularly low or when the applied microwave power is small, the start of discharge itself may not easily occur depending on conditions.

It is an object of the present invention to provide a plasma apparatus which solves the problem that discharge initiation is unlikely to occur under such conditions.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an electron cyclotron resonance (EC) of electrons moving in a magnetic field and microwaves.
R) in a plasma apparatus for generating plasma
Position with magnetic field strength at which ECR occurs (ECR point)
Is present in the region where the microwave coincides with the position of the antinode of the standing wave formed before the start of discharge, or in the region where the electric field intensity is 70% or more of the electric field intensity of the antinode in the vicinity of the antinode. It is characterized by the following.

[0008]

In the conventional apparatus structure shown in FIG. 2, the microwave 9 introduced into the plasma generating chamber 5 is almost reflected by the substrate support 7 until plasma is generated in the plasma generating chamber 5. In many cases, the standing wave 10 is formed on the front surface of the substrate support. As shown in FIG. 2, when the ECR point 16 is located around the nodes 12 and 14 of the standing wave, the ECR point 1
6, the intensity of the electric field acting on the electrons is small, and the electrons are not efficiently accelerated. On the other hand, ECs
With the R point, an electric field that is twice as large as that in the case of only the incident wave acts on the electrons at the ECR point, so that the electrons are efficiently accelerated and the discharge starts easily.

[0009]

FIG. 1 is a view for explaining an embodiment of the present invention, and shows a state before the start of discharge. From a microwave introduction window 4 made of quartz, a microwave 9 of 2.45 GHz and 100 W
When introduced into the plasma generation chamber 5 filled with 0 ^-3 Pa Ar gas, the microwave 9 is applied to the aluminum substrate support 7.
And standing waves 10 are formed on the front surface of the substrate support 7. The antinode of the standing wave closest to the substrate support 7 (first antinode 1)
The position 1) is a position 3.1 cm away from the substrate support. EC corresponding to microwave frequency of 2.45 GHz
The R point 16 (magnetic field intensity 875 G) is adjusted to the position of the first antinode 11 by adjusting the current of the coil 6. Electrons at the position of the first antinode 11 are efficiently accelerated by the ECR, so that a low gas pressure of 10 ⁻³ Pa, 10
Even with a small power of 0 W, the discharge is started without delay at the same time as the application of the microwave power.

[0010]

As described above, according to the present invention, the EC
The start of discharge in the R plasma device can be always stably performed even at the time of low gas pressure or low microwave power,
Higher control of the plasma process is achieved. As a result, a dry etching process using this plasma
Higher control and stabilization of the process can be achieved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of an ECR plasma device according to the present invention.

FIG. 2 is an explanatory diagram of a conventional ECR plasma device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 microwave oscillation tube 2 waveguide 3 tapered waveguide 4 microwave introduction window 5 plasma generation chamber 6 coil 7 substrate support 8 substrate 9 microwave 10 standing wave 11 first antinode 12 first node 13th 2 belly 14 2nd node 15 external magnetic field 16 ECR point

Claims (1)

(57) [Claims] In a plasma apparatus for generating plasma by electron cyclotron resonance (ECR) of electrons moving in a magnetic field and a microwave, a position (ECR point) having a magnetic field intensity at which the ECR occurs is determined by a point at which the microwave starts discharging. Either the position of the antinode of the standing wave coincides with the position of the antinode of the standing wave formed before, or the electric field intensity around the antinode is 7
A plasma device, wherein the plasma device is present in an area of 0% or more.