JPH012321A - plasma etching equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Structure of the Invention] (Industrial Application Field) The present invention relates to a plasma etching apparatus for etching a workpiece such as a semiconductor wafer using plasma.

(Prior Art) Conventional plasma etching Wlt2: There is a parallel plate type plasma etching apparatus. Parallel plate forming plasma etching equipment generates plasma by applying a high-frequency electric field to the etching gas introduced between the top plate electrodes, and accelerates the generated plasma to etching 1 trillion lines of the top plate electrode. A workpiece placed on one side is etched. It is known that the etching rate in this plate type plasma etching apparatus depends on the type of etching gas, ion acceleration, and ion density. Therefore, in order to increase the etching speed when the type of etching gas is determined, it is necessary to increase the ion acceleration,
The ion density is increased.

(Problem to be solved by the invention) However, in an attempt to increase the etching rate in a conventional plasma etching apparatus, when the high-frequency voltage applied between the parallel plate electrodes is increased to increase the ion acceleration, high-speed ions are generated on the surface to be processed. There was a problem in that the crystals of the object to be processed were damaged due to collision and physical sputtering.

Another problem is that when the pressure of the etching gas is increased to reduce the etching speed, the accelerated ions and neutral particles collide, and the sides of the etching groove are etched by the collided neutral particles, making it impossible to form fine patterns. was there.

The present invention has been made with the above-mentioned circumstances in mind, and an object of the present invention is to provide a plasma etching apparatus that can perform high-speed etching without damaging the workpiece.

[Structure of the invention]

(Means for Solving the Problems) The above purpose is to provide a first plate electrode on which the object to be processed is placed, and a second plate electrode disposed approximately parallel to the first plate electrode.
A high-frequency power supply that applies a high-frequency electric field between the T row plate electrodes, the first and second row plate electrodes, and an etching gas between the first and second parallel plate electrodes. A microwave application means for applying microwaves, and a confining magnetic field that confines the generated plasma between the first and second parallel plate electrodes is applied to the etching gas between the first and second parallel plate electrodes. This is achieved by a plasma etching apparatus characterized in that it is equipped with a magnetic field applying means.

(Function) Since the present invention is configured as described above, the etching gas is generated by exciting it with microwaves, and the generated plasma is confined between the +2 row and the flat plate pole by the magnetic field applying means. Etching is performed using this confined plasma.

(Example) A plasma etching apparatus according to an example of the present invention was
As shown in the figure. In this plasma etching apparatus, a quartz tube 2 is provided on the inner surface of a vacuum container 1, and etching gas is introduced into the quartz tube 2 from a gas inlet pipe (not shown) and from a gas exhaust pipe (not shown). Etching gas is exhausted. Inside the quartz tube 2 is a parallel plate electrode 4.
．． It is provided for 6 tl. A wafer 5 to be etched is placed on the parallel plate electrode 4 on the side. A blocking capacitor 8 and a high frequency power source 9 connected in series are connected to the middle plate electrode 4.6 of the first row.
- A high frequency voltage (RF) is applied between the 1st row and the I4 temporary electrode 4.6. In this embodiment, the plate electrode 4.6
The bias voltage applied between them acts to accelerate the confined plasma ions.

In this example, the etching gas was heated using microwaves (2, 45
CIIZ) to generate plasma.

A magnetron 10 is provided for generating microwaves. In order to introduce the microwave from the magnetron 10 into the vacuum vessel 1, the waveguide 3 is connected to the magnetron 1.
0 to the vacuum container 1. Also, vacuum container 1
There are two coils 7 above and below to generate a magnetic field.
A and 7B are provided. The planes of the coils 7A, 7B are substantially parallel to the parallel plate electrodes 4.6, as shown in FIG. Plasma is generated by the action of the magnetic field generated by the coils 7A and 7B and the high frequency electric field generated by microwaves on the etching gas.

The magnetic field generated by the coils 7A, 7B is
When a current flows in the same direction through B, the dashed dotted line Mmi in Figure 1
It becomes a mirror magnetic field as shown by rror, and the coil 7A,
When a current in the opposite direction is passed through 7B, the two-dot chain line Mcu appears in Figure 1.
This results in a cusp magnetic field as shown by sp. Both the mirror magnetic field and the cusp magnetic field function as a confining magnetic field to confine the generated plasma between the parallel plate electrodes 4.7. Thereby, the concentration of plasma contributing to etching can be increased between the parallel plate electrodes 4.7.

The operation of this embodiment will be explained. First, etching gas is introduced into the quartz tube 2 having a vacuum volume S1. Coil 7A, 7B
A current is applied to generate a magnetic field, and a microwave is generated by the magnetron 10, and the magnetic field and high frequency electric field are applied to the etching gas to generate plasma. Further, a high frequency electric field is applied from a high frequency power source 9 between the parallel plate electrodes 4.7 to generate plasma. Since a bias voltage is applied between the parallel plate electrodes 4 and 6 by the blocking capacitor 8, plasma ions are accelerated by this bias voltage, and the wafer 5 placed on the parallel plate electrode 4 is etched.

At this time, the plasma is generated by the confining magnetic field MmirOr・Mcu
sp is confined between parallel plate electrodes 4.6.

As described above, according to this embodiment, plasma is generated by the action of microwaves and a magnetic field, and the generated plasma is confined between the parallel plate electrodes by the confining magnetic field, so that the ion density of the plasma used for etching can be reduced. It can be made higher. Then, the ions are accelerated by the bias voltage between the horizontal plate electrodes, and etching can be performed at high speed without damaging the wafer. Further, in this embodiment, since the magnetic lines of force are along the direction in which the ions are accelerated, there is an effect that the ions can easily move and be accelerated.

A plasma etching apparatus according to another embodiment of the invention is shown in FIG. Components that are the same as those in the embodiment shown in FIG. 1 are given the same reference numerals, and their explanations will be omitted. This embodiment differs from the previous embodiment in the coil that generates the magnetic field. The coils 11A111B in this embodiment are located on both sides of the parallel plate electrode 4.7, and the coil surfaces are perpendicular to the parallel plate electrode 4.7. When currents in the same direction flow through coils IIA and IIB, the magnetic fields generated by coils IIA and IIB become mirror magnetic fields as shown by the dashed line Mmirror in FIG. When flowing, a cusp magnetic field as shown by the two-dot chain line Mcusp in FIG. 2 is created. Both the mirror magnetic field and the cusp magnetic field function as a confining magnetic field to confine the generated plasma between the parallel plate electrodes 4.7.

In this way, the plasma generated in this example is also confined between the parallel plate electrodes by the confining magnetic field.
The density of ions contributing to etching can be increased, and etching can be performed at high speed.

The present invention is not limited to the above-mentioned embodiments, and can be modified in various ways. For example, in the embodiment described above, the confining magnetic field was generated and applied using two coils, but any magnetic field can be used as long as it can apply a magnetic field that can confine the plasma between 14 rows and 1 plate electrode. It can also be a configuration.

Further, in the above embodiment, microwaves were introduced by connecting a waveguide to the side surface of the vacuum container, but microwaves may be introduced from any direction as long as plasma can be generated by applying them to the etching gas. Furthermore, it goes without saying that what is etched is not limited to mid-conductor wafers.

〔Effect of the invention〕

As described above, according to the present invention, plasma is generated using microwaves and a magnetic field, and the generated plasma is confined between the parallel plate electrodes using a confining magnetic field and used effectively, so that no damage is caused to the object to be processed. It can be etched at high speed without giving any damage.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a plasma etching apparatus according to one embodiment of the invention, and FIG. 2 is a sectional view showing a plasma etching apparatus according to another embodiment of the invention. 1... Vacuum vessel, 2... Quartz tube, 3... Waveguide,
4.6...Parallel plate electrode, 5...Wafer, 7A,
7B, IIA, IIB...Coil, 8...Producting capacitor, 9...High frequency power supply, 10...Magnetron. Applicant's agent Mr. Sato

Claims (1)

[Claims] 1. A first parallel plate electrode on which an object to be processed is placed; a second parallel plate electrode disposed substantially parallel to the first plate electrode; and the first and second parallel plate electrodes. a high-frequency power source that applies a high-frequency electric field between the two parallel plate electrodes; a microwave applying means that applies microwaves to the etching gas between the first and second parallel plate electrodes; A plasma etching apparatus comprising: magnetic field applying means for applying a confining magnetic field to the plasma between the first and second parallel plate electrodes to confine it between the first and second parallel plate electrodes. . 2. The plasma etching apparatus according to claim 1, wherein the magnetic field applying means includes a pair of coils whose surfaces are substantially perpendicular to the first and second parallel plate electrodes. Etching equipment. 3. In the plasma etching apparatus as set forth in claim 2, the magnetic field applying means causes current to flow in the same direction through the pair of coils, and applies a mirror magnetic field as the confining magnetic field. Plasma etching equipment. 4. The plasma etching apparatus according to claim 2, wherein the magnetic field applying means applies currents in opposite directions to the pair of coils to apply a cusp magnetic field as the confining magnetic field. plasma etching equipment. 5. The plasma etching apparatus according to claim 1, wherein the magnetic field applying means includes a pair of coils whose surfaces are substantially parallel to the first and second parallel plate electrodes. Etching equipment. 6. In the plasma etching apparatus as set forth in claim 5, the magnetic field applying means causes current to flow in the same direction through the pair of coils, and applies a mirror magnetic field as the confining magnetic field. Plasma etching equipment. 7. In the plasma etching apparatus according to claim 5, the magnetic field applying means applies a cusp magnetic field as the confining magnetic field by passing current in opposite directions to the pair of coils. Plasma etching equipment.