JPS5927213B2 - plasma reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in the etching characteristics and film forming characteristics of a parallel plate type plasma etching and plasma CVl) film forming apparatus.

Conventional parallel plate plasma etching and plasma CV
A schematic diagram of the D film forming apparatus is shown in FIG.

In the conventional device, all-polar high-frequency electrodes 1 and 2 are arranged in a vacuum chamber 3 in a counter-electrode structure, and, as shown in FIG. 1 and 2, gas plasma 6
is generated between electrodes 1 and 2. The plasma generation conditions are determined by the distance between electrodes 1 and 2, the gas pressure between the electrodes, and the frequency of the applied high frequency. This condition is known as Patsien's law for high frequency discharges. Now, when performing so-called plasma etching using such a parallel plate type plasma generator, for example, the material to be etched 5
For example, a silicon substrate or a silicon compound formed on the silicon substrate is placed on one surface of the counter electrode, as shown in FIG. For example, it is widely used in the production of semiconductor devices.
When etching a silicon oxide film or a silicon oxide film containing phosphorus or arsenic to be used, the gas used is C9F8 gas, CHF3 gas, CF4+H2 gas, or the like. In order to perform etching stably, the plasma 6 between the opposing electrodes 1 and 2 must be stably formed,
Moreover, it is necessary to stabilize the plasma state near the surface T of the material 5 to be etched. The plasma state near the surface 1 depends on the way the gas flows between the opposing electrodes 1 and 2, the concentration distribution of the gas, and especially the concentration distribution and flow velocity distribution of the gas near the surface of the material 5 to be etched. Usually the first
In the apparatus shown in the figure, it is difficult to maintain a stable plasma state. For example, instabilities such as changes in etching characteristics each time etching is unavoidable in the structure shown in FIG. 1. The purpose of this invention is to
A magnetic field generating member is embedded in a part or the entire surface of the opposing electrodes 1 and 2, and the plasma state between the electrodes 1 and 2 is stabilized by the effect of applying a magnetic field. The detailed contents of this invention will be explained below according to the embodiment shown in FIG.

The embodiment shown in FIG. 2 is composed of metal counter electrodes 1, 2, a vacuum chamber 3, a high frequency power source 4, and a magnet 9 embedded in the counter electrodes 1, 2. In this embodiment, permanent magnets are embedded in the electrodes 1, 2 corresponding to the location of the material 5 to be etched. Next, the operation and effects of this embodiment will be explained. As in the case of FIG. 1, the counter electrode 1,
After operating the exhaust system 8 to evacuate the inside of the vacuum chamber 3 in which the etching material 2 is placed to a predetermined pressure, a gas matching the material 5 to be etched, for example, in the case of a silicon oxide film, is added to the vacuum chamber 3. C3F8 gas is introduced, and the gas pressure in the vacuum chamber 3 is maintained at a predetermined value, for example, 0.1 t0rr. Next, the high frequency power source 4 is operated to apply high frequency power at a predetermined frequency (for example, 1 KW at 13 MHz) between the opposing electrodes 1 and 2 to generate plasma between the opposing electrodes 1 and 2. In the case of FIG. 2, a static magnetic field 10 exists in the direction perpendicular to the surfaces of the opposing electrodes 1 and 2 due to the magnet 9 embedded in the electrode 1 or both electrodes 1 and 2 in advance. This static magnetic field is applied to the corresponding electrode 1
When a high-frequency discharge is generated between Since the direction of movement of electrons and ions in the plasma, which contribute to maintaining a stable plasma state, is controlled by magnetic lines of force, it serves to form a stable plasma state between the opposing electrodes 1 and 2. FIG. 3 shows the plasma stability and plasma maintenance time by comparing the conventional device shown in FIG. 1 with the embodiment shown in FIG. 2 of the present invention. In the case of FIG. 2 (indicated by a broken line), it was confirmed that the stability of the plasma was clearly better than in FIG. 1 (indicated by a solid line), and the time required to reach a stable state was significantly shorter. Furthermore, by using the embodiment shown in FIG. 2 for etching a silicon oxide film, for example, the uniformity of the etching amount within the substrate 5 was significantly improved. For example, uniformity was improved by about 3 times under the same plasma conditions. The above explanation shows that the plasma between the opposing electrodes 1 and 2 can be stabilized by embedding the magnetic field generating magnet 9 in the opposing electrodes 1 and 2.

The plasma state, especially the plasma state near the surface of the material 5 to be etched, influences the etching characteristics. Therefore, in another embodiment, instead of the recessed permanent magnet 9,
FIG. 4 shows an example in which a magnetic field generating coil 11 for forming an electromagnet is embedded in the opposing electrodes 1 and 2. In this case, a direct current is applied to the recessed coil 11 from the outside to generate a static magnetic field between the opposing electrodes 1 and 2, but the strength of this static magnetic field can be changed depending on the value of the direct current flowing through the coil 11. It can change to Therefore, the plasma state between the opposing electrodes 1 and 2 and near the surface of the material 5 to be etched can be greatly changed by the direct current flowing through this coil 11, and the etching characteristics can be controlled arbitrarily from the outside. .
Furthermore, the apparatus of the present invention can be applied not only to plasma etching but also to film formation by plasma CVD (chemical vapor deposition).

[Brief explanation of the drawing]

Fig. 1 is a conceptual diagram of a conventional device, Fig. 2 is a conceptual diagram showing an embodiment of the device of the present invention, Fig. 3 is a diagram for explaining the operation of the present invention, and Fig. 4 is a conceptual diagram of another embodiment of the device of the present invention. It is a conceptual diagram showing an example. In the figure, 1 and 2 are high frequency electrodes, 3 is a vacuum chamber, 4 is a high frequency power supply, 5 is a material, 6 is a plasma, 7 is near the surface, 8 is an exhaust system, 9 is a permanent magnet, 10 is a static magnetic field, and 11 is a The coil is shown.

Claims (1)

[Claims] 1. A plasma reaction device characterized in that a magnetic field generating member is embedded in a part or the entire surface of parallel plate type high frequency electrodes that are arranged oppositely in a vacuum chamber.