JP2933507B2 - Plasma etching 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 plasma etching apparatus, and more particularly to a plasma etching apparatus for increasing the density of a plasma by a magnetic field.

[0002]

2. Description of the Related Art FIGS. 2A and 2B show a conventional plasma etching apparatus, wherein FIG. 2A is a top view and FIG. 2B is a side sectional view. In the figure, upper outer wall 12 and side outer wall 11
The magnetic field coil 8 is disposed in contact with the outer surface of the side outer wall 11 of the reaction chamber 2 surrounded by the above. A sample (for example, a semiconductor wafer) 7 to be plasma-etched is placed in the reaction chamber 2, the reaction chamber 2 is evacuated, an etching gas is introduced from a gas introduction pipe 3, and the electrode 4 is connected to the electrode 4 via a blocking capacitor 6. A predetermined etching is performed on the sample 7 by generating a plasma by applying a high frequency voltage from the high frequency power supply 5. Assuming that the magnetic field is B and the electric field is E, the generated plasma has a structure in which the density is increased by an E × B drift due to an electrically rotating one-way magnetic field.

FIG. 3 is a view showing another conventional plasma etching apparatus as disclosed in Japanese Patent Application Laid-Open No. Hei 4-236428, in which (A) is a top view and (B) is a side sectional view. It is. In the figure, a plurality of permanent magnets 9 are arranged in contact with the upper side of the outer surface of the side outer wall 11 of the reaction chamber 2 surrounded by the upper outer wall 12 and the side outer wall 11, and the density of the plasma is increased by the magnetic field B. It has a structure.

[0004]

In the prior art shown in FIG. 2, however, the magnetic field B (direction) acts on the sample 7 horizontally and the electric field E acts on the specimen in a vertical direction. B moves rightward with respect to B, and the plasma density in that portion increases. Thereby, the plasma density on the outer periphery of the inside of the reaction chamber increases. Therefore, there is a problem that the plasma density at the outer periphery of the inside of the reaction chamber is increased and a difference from the center at the inside occurs, and the etching rate is higher at the outer periphery of the sample than at the center. Further, there is also a problem that gate breakdown of a transistor formed in a semiconductor sample due to non-uniform plasma occurs.

In the prior art of FIG. 3 as well, the magnetic field B generated by adjacent permanent magnets is also concentrated on the outer periphery of the reaction chamber, and the E × B drift of the plasma also occurs on the outer periphery of the reaction chamber. 2 has the same problems as the prior art.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a plasma etching apparatus capable of obtaining a high-density plasma having a uniform distribution, thereby making the etching rate on a sample uniform and causing no damage in the sample.

[0007]

SUMMARY OF THE INVENTION The present invention is characterized in that a reaction chamber surrounded by an upper outer wall and a side outer wall, an electrode provided in the reaction chamber, and a gas for introducing an etching gas into the reaction chamber. A plasma etching apparatus , comprising: an inlet tube; and increasing the density of plasma by means of a magnetic field.
An elongated magnetic field coil that extends linearly from the center to the periphery
Of the same number of adjacent magnetic field coils
The plasma etching apparatus is arranged radially so that the magnetic fields are adjacent to each other, and an alternating current of opposite phase is applied to the adjacent magnetic field coils to generate the magnetic field.

[0008]

According to the structure of the present invention, an alternating current having an opposite phase is applied to the adjacent magnetic field coils, so that the plasma drift in the reaction chamber caused between the adjacent coils is reduced. In the opposite direction and alternately, so that the density of the plasma is offset as a whole and a high density plasma with a uniform distribution is obtained.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a plasma etching apparatus according to one embodiment of the present invention, in which (A) is a top view and (B) is a side sectional view.

The outer wall of the reaction chamber 2 surrounded by the upper outer wall 12 of the circular body and the side outer wall 11 of the cylindrical body is grounded, and the electrode 4 is provided therein, and the electrode 4 is processed by plasma etching. A sample 7 such as a semiconductor wafer to be mounted is placed,
The reaction chamber 2 is evacuated to vacuum, an etching gas is introduced into the inside through a gas introduction pipe 3 connected to the center of the upper outer wall 12, and a high-frequency voltage is applied from a high-frequency power supply 5 to the electrode 4 via a blocking capacitor 6. To generate plasma.

The means for increasing the density of the plasma in this embodiment is as follows.

That is, a plurality of magnetic field coils 1 are radially arranged along the outer upper surface of the upper outer wall 12 of the reaction chamber 2, and an alternating current of opposite phase is supplied to the adjacent magnetic field coils 1. Therefore, the number of magnetic field coils 1 needs to be an even number. In this embodiment, twelve magnetic field coils 1 are arranged at equal intervals of 30 °, and an alternating current is supplied from a source 13F to a certain magnetic field coil 1. An alternating current having a phase opposite to that of the alternating current source 13F flows from the alternating current source 13R to the magnetic field coil 1 adjacent thereto.

By arranging a plurality of magnetic field coils 1 radially and passing alternating currents of opposite phases to adjacent magnetic field coils, a magnetic field generated between adjacent magnetic field coils as shown in FIG. B alternates in the opposite direction.

As a result, in the reaction chamber 2, the E × B drift of the plasma due to the magnetic field B drifts from the center to the outer periphery under a certain coil, and from the outer periphery to the center under the adjacent coil. ExB drift. In this way, the direction is alternately reversed and drifts.

Next, when the coil current is shifted by a half cycle, it reverses, so that under one coil, the plasma drifts repeatedly from the center to the outer periphery and from the outer periphery to the center.

As a result, the density of the plasma at the center and the outer periphery of the reaction chamber 2 are offset, and a high-density plasma having a uniform distribution can be obtained.

The drift of the plasma is generated in the reaction chamber 2.
Since the process is performed only at the upper portion inside, the interval with the sample 7 can be easily maintained, and from this point, the sample is less likely to be damaged by the fluctuation of the plasma density.

[0019]

As described above, according to the present invention, a plurality of magnetic coils are radially arranged along the outer surface of the upper outer wall of the reaction chamber, and alternating currents of opposite phases are supplied to adjacent magnetic coils. As a result, the resulting drift of the plasma in the reaction chamber occurs between the adjacent coils in the opposite direction and alternately, and the direction alternates with time. As a result, the density of the plasma is offset as a whole, and a high-density plasma with a uniform distribution is obtained. As a result, the etching rate on the sample becomes uniform,
Etching within the sample is performed uniformly. Further, damage to the sample is reduced.

[Brief description of the drawings]

FIG. 1 is a view showing a plasma etching apparatus according to an embodiment of the present invention, wherein (A) is a top view and (B) is a side sectional view.

FIGS. 2A and 2B are views showing a conventional plasma etching apparatus, wherein FIG. 2A is a top view and FIG. 2B is a side sectional view.

3A and 3B are diagrams showing another conventional plasma etching apparatus, wherein FIG. 3A is a top view and FIG. 3B is a side sectional view.

[Description of Signs] 1 Magnetic field coil 2 Reaction chamber 3 Gas introduction tube 4 Electrode 5 High frequency power supply 6 Blocking capacitor 7 Sample 8 Magnetic field coil 9 Permanent magnet 11 Side outer wall 12 Upper outer wall 13F, 13R AC source

Claims (1)

(57) [Claims] A reaction chamber surrounded by an upper outer wall and a side outer wall; an electrode provided in the reaction chamber; and a gas introduction pipe for introducing an etching gas into the reaction chamber.
In a plasma etching apparatus for increasing the density of plasma by a magnetic field , the gas is placed on an upper outer wall of the reaction chamber.
Straight from the center to the periphery
The even number of elongated magnetic field coils
Are arranged radially so that the angles between the il are all the same ,
A plasma etching apparatus, wherein alternating currents having opposite phases are supplied to adjacent magnetic field coils to generate the magnetic field.