JPS5927212B2 - plasma reactor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a parallel plate electrode type plasma reactor.

FIG. 1 is a schematic sectional view showing a conventional parallel plate electrode plasma reactor. In the figure, 1 is a chamber, 2 is an exhaust port for exhausting the inside of the chamber 1, 3 is an upper electrode, 4 is a lower electrode, and 5 is a 6 is a reaction gas inlet for introducing a reaction gas to be fed into the chamber 1 through the internal passage of the upper electrode 3; 6 is a reaction gas ejector L7 is a workpiece placed on the lower electrode 4; 8 is an upper and lower part; This is a high frequency power source that applies a high frequency voltage between electrodes 3 and 4.

This device evacuates the inside of the chamber 1 to a predetermined low pressure using a vacuum pump (not shown) from an exhaust port 2, and then injects a reaction gas corresponding to the required plasma reaction from a reaction gas inlet 5 into a reaction gas injection hole. 6 into the chamber 1, the high frequency plate power supply 8 is operated, a high frequency voltage is applied between the upper and lower electrodes 3 and 4, and plasma is generated between the two electrodes.

This device uses plasma etching. It is used for plasma deposition, etc., and in plasma etching, the reaction gas is changed depending on the material of the workpiece 7. For example, if the workpiece 7 is silicon Si or a Si compound, CF4
- C3F3 or C4F3 or a mixed gas of these and oxygen O2 is mainly used. Inorganic or organic gas such as CCT4, BCT3, trichlorethylene, etc. is used for etching aluminum Aι or At alloy. Further, in the case of depositing Si or a Si compound, gases such as SiH4, SiH4+NH3, and SiN4+N2 are used. The plasma generation conditions are the distance between the electrodes 3 and 4, and the gas pressure of the gas used. It is determined by the frequency of the applied high-frequency wave, and this condition is known as Patsien's law for high-frequency discharge. Now,
For example, when etching a SiO2 film, the main reactive species that precede the etching reaction are CF, Xy radicals and Cx.
It is thought to be Fy ion.

The concentration of these main reactive species in the plasma and the concentration and distribution near the surface of the workpiece 7 greatly influence the etching rate of the SiO2 film and the selective etching properties between the SiO2 film and the underlying Si substrate. Naturally, this greatly depends on the flow velocity distribution of the reactive gas near the surface of the workpiece 7. Therefore, in the conventional device shown in Fig. 1, in order to control these factors, it is necessary to adjust the reaction gas pressure [gas concentration between the opposing electrodes 3 and 4], the way the reaction gas flows, and the high-frequency power. However, it is not easy to maintain a stable plasma state, and the above-mentioned adjustment is critical, and it is practically impossible to control the factors. Therefore, artificial control of the above-mentioned main reactive species necessary for improving etching properties was not possible. This invention was made in view of the above points, and it is a parallel plate electrode type plasma that can control the plasma state by forming a static magnetic field in a direction parallel to the plane of the parallel plate electrodes and controlling this magnetic field. The purpose is to provide a reactor.

FIG. 2 is a schematic sectional view showing one embodiment of the present invention.
The same parts as in the conventional example in the figure are indicated by the same reference numerals, and the explanation thereof will be omitted.

In the figure, reference numerals 9a and 9b are control static magnetic field generating coils that are provided on both sides of the chamber 1 and generate a static magnetic field parallel to the electrode surface between the upper electrode 3 and the lower electrode 4. H shown by a dashed line in the figure is this static magnetic field. In order to perform plasma reaction treatment on the workpiece 7 using this embodiment apparatus, the workpiece 7 is placed on the lower electrode 4 and the inside of the chamber 1 is evacuated through the exhaust port 2, as in the conventional example. Then, the pressure inside the chamber 1 is made to be 10-2T0rr or less. Next, a reaction gas required for the plasma reaction is introduced into the chamber 1 from the reaction gas inlet 5, and the pressure inside the chamber 1 is maintained at a predetermined value, for example, 0.1 to 1.0T0rr. After the pressure within the chamber 1 is sufficiently stabilized, the high frequency power supply 8 is operated to supply high frequency power of a predetermined frequency and power, for example, 13 MHz, 11000 W, between the upper and lower electrodes 3 and 4. By supplying this high frequency power, plasma is generated between both electrodes 3 and 4. Next, a current is passed through the control static magnetic field generating coils 9a} and 9b to generate a static magnetic field H parallel to the electrode surfaces of both electrodes 3} and 4. The strength of the static magnetic field H, that is, the magnetic flux density, can be easily adjusted by adjusting the current flowing through the coils 9a and 9b.
By applying this parallel static magnetic field H, the plasma between the electrodes 3 and 4 can be stabilized, and by adjusting the strength of this static magnetic field H, the plasma state between the electrodes can be adjusted. It is possible to control the plasma state near the electrode surface, and it is also possible to control the concentration and distribution of the main reactive species that contribute to the plasma reaction, as well as the types of reactive species. This is because the static magnetic field H acts on the plasma, controls the spatial distribution of the plasma, and controls the movement of charged particles such as electrons and ions that contribute to various collision processes. For example, when plasma etching the aforementioned SiO2 film using C3F8 or C4F8 gas, the concentration and energy of CxFy radicals and CF ions can be controlled.

FIG. 3 is a schematic sectional view showing another embodiment of the present invention. In this embodiment, control static magnetic field generating coils 9a and 9b are provided near the lower electrode in the chamber 1, and near the surface of the lower electrode 4. This embodiment is the same as the embodiment shown in FIG. 2, except that the control static magnetic field is effectively formed only in the region where the control static magnetic field is generated.

Although plasma etching has been mainly described above, the present invention can also be applied to the production of various inorganic and organic films by plasma chemical vapor deposition (plasma CVD) and the control of their film quality.

As detailed above, in the plasma reactor according to the present invention, since a static magnetic field parallel to the opposing surfaces of the high-frequency electrodes is supplied between the high-frequency electrodes, the plasma state can be controlled.
It becomes possible to control the concentration and distribution of the main reactive species that contribute to the plasma reaction, as well as the types of reactive species, making it easy to adjust the plasma reaction.

[Brief explanation of drawings]

Fig. 1 is a schematic sectional view showing a conventional parallel plate electrode type plasma reactor, Fig. 2 is a schematic sectional view showing one embodiment of the present invention, and Fig. 3 is a schematic sectional view showing another embodiment of the invention. It is a diagram. In the figure, 1 is a chamber, 2 is an exhaust port, 3 is an upper electrode, 4 is a lower electrode, 5 is a reaction gas inlet, 7 is a workpiece,
8 is a high frequency power supply, 9a} and 9b are control static magnetic field generating coils, and H is a static magnetic field.

Claims (1)

[Claims] 1. Plasma is generated by applying a high frequency high voltage between two electrodes arranged parallel to each other and facing each other in a chamber maintained in a predetermined atmosphere, and plasma is generated between the two electrodes. A plasma reaction apparatus for subjecting a placed workpiece to plasma reaction treatment, characterized in that a static magnetic field is supplied between the two electrodes parallel to their opposing surfaces. 2. The plasma reaction apparatus according to claim 1, wherein the supplied static magnetic field has a variable magnetic flux density.