JPS5812346B2 - plasma etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma etching apparatus for dry etching in the manufacturing process of semiconductor devices.

Conventionally, two types of facing electrode type (for example, parallel plate type) plasma etching apparatuses have been used: a cathode couple type apparatus and an anode couple type apparatus.

FIG. 1 is a diagram illustrating the principle of the main part structure of the cathode couple facing electrode type plasma etching apparatus.

In the figure, 1 is an object to be etched, 2 is a cathode (on the side where the object to be etched is placed), 3 is an anode electrode, 4 is a high frequency power source, and 5 is a blocking capacitor.

High frequency power source 4 (e.g. 13.56MHz)
When plasma is generated using an electric field, the ions cannot follow the high-frequency electric field, so a self-bias voltage is generated on the side to which the high-frequency wave is applied (cathode electrode). It corresponds to the application side.

Therefore, etching becomes directional, and fine processing without side etching is performed.

FIG. 2 is a diagram illustrating the principle of the main part configuration of the anode couple facing electrode type plasma etching apparatus.

In the figures, the same reference numerals as those mentioned above indicate the same or equivalent parts.

6 is a high frequency power source, which is connected to the anode electrode 3.

When plasma is generated using a low frequency power source 6 (for example, 500 kHz), the sulfur oxide moves following changes in the electric field. If you leave it on, you can perform directional etching.

In both the cathode-coupled type (Fig. 1) and anode-coupled type (Fig. 2) devices described above, if you try to increase the plasma density in order to increase the etching rate, you will inevitably have to reduce the applied power. This has the disadvantage that the ion energy increases, causing damage to the element (semiconductor device) and deterioration of the resist of the mask.

In addition, in the anode-coupled type, ions are accelerated on the θ side of the high frequency, but electrons are accelerated on the ■ side, and the incidence of the electrons on the object to be etched 1 also causes damage to the element and deterioration of the resist of the mask. was there.

The present invention eliminates the drawbacks of the conventional technology described above, and provides a plasma etching apparatus that increases the etching rate and improves work efficiency while preventing damage to elements (semiconductor devices) and deterioration of resist. The purpose is to

In order to achieve the above object, the plasma etching apparatus of the present invention includes an anode electrode, a cathode electrode on which an object to be etched is placed, and a device for generating plasma by gas discharge and accelerating ions on the cathode electrode side. In the apparatus of the present invention configured in this way, the apparatus is equipped with an opposed electrode type plasma etching region equipped with a high frequency power source, and an introduction plasma generation section for additionally introducing plasma into the plasma etching region. By introducing the plasma generated in the area (introduced plasma generation part) into the etching area, the density of the plasma, that is, the ion current density reaching the object to be etched, and the energy of the ions incident on the object to be etched can be independently controlled. Can be controlled.

Therefore, by changing the density of the introduced plasma, it is possible to freely change the ion energy while keeping the plasma density constant.

The present invention will be explained in detail below using examples.

FIG. 3 shows a first embodiment of the apparatus of the present invention, and is a diagram for explaining the principle of the configuration of its main parts.

In the figure, 7 is a cathode electrode for generating introduced plasma, 8
Reference numeral 9 indicates a common anode electrode serving both for the plasma etching region and for generating introduced plasma, and 9 indicates a high frequency power source for generating introduced plasma, and these constitute an introduced plasma generation section.

The common anode electrode 8 is a mesh or a perforated plate, and plasma is generated between the electrode 8 and the cathode electrode 7 by drawing a high frequency power supply, and the plasma passes through the holes of the common anode electrode 8 into the plasma etching area space. (between the common anode electrode 8 and the cathode electrode 2).

The operation of the apparatus of the present invention configured as described above is as follows.

The inside of the apparatus is evacuated by a vacuum pump, a reactive gas such as freon, carbon tetragonide, etc. is introduced, and the pressure is maintained at a predetermined pressure, for example, Pa to several tens of Pa.

Since the plasma generated in the introduced plasma generating section is introduced into the plasma etching area space through the hole of the common anode 8, the density of the plasma generated by the high frequency power source 4 in that space is higher than before the introduced plasma is generated. do.

Therefore, the power of the high frequency power source 4 can be kept low compared to the case where plasma of the same density is generated alone in the etching region space (corresponding to the case of FIG. 1).

FIG. 4 shows a second embodiment of the apparatus of the present invention, and is a principle explanatory diagram of the main structure thereof.

10 is a microwave generation source, 11 is a waveguide, and 12 is a magnet coil for plasma generation by electron cyclotron resonance.

This device diffuses and introduces plasma generated by microwaves (for example, 2.45 GHz) into a cathode couple facing electrode type (parallel plate type) device with a structure similar to the conventional type shown in Figure 1. The operation is similar to that of the first embodiment (FIG. 3) in that the plasma density is increased.

As explained above, in the plasma etching apparatus of the present invention, by introducing plasma generated in another system into the opposed electrode type plasma etching region space, the plasma density in the space can be increased.

Therefore, in order to obtain the same plasma density, less power needs to be applied between the opposing electrodes than in the conventional device.

The self-bias voltage that determines the energy of ions incident on the object to be etched depends on the high-frequency power applied between opposing electrodes, so if the plasma density is the same, the incident ion energy can be lower than with conventional equipment. .

This has the advantage that the ion energy can be kept low even under high-density plasma that increases the etching rate, minimizing damage to the element (semiconductor device) and deterioration of the resist. It turns out.

[Brief explanation of drawings]

The drawings are all principle explanatory diagrams of the main parts of the plasma etching device, and Fig. 1 shows the conventional cathode couple facing electrode type, Fig. 2 shows the conventional anode couple facing electrode type, and Fig. 3 shows the present invention. FIG. 4 shows an apparatus according to a second embodiment of the present invention. 1... Etched object, 2... Cathode electrode, 3... Anode electrode, 4, 6, 9...
...High frequency power supply, 5 ... Blocking capacitor, 7 ... Cathode electrode, 8 ...
Common anode electrode, 10...Microwave generation source, 11... Waveguide, 12... Magnet coil.

Claims (1)

[Claims] 1. A facing electrode type plasma etching region comprising an anode electrode, a cathode electrode on which an object to be etched is placed, and a high frequency power source for generating plasma by gas discharge and accelerating ions toward the cathode electrode; 1. A plasma etching apparatus comprising an introduction plasma generating section for additionally introducing plasma into a plasma etching region.