JPH0830275B2 - Rotating magnetic field type magnetron etching device - Google Patents

Description

The present invention relates to a rotating magnetic field type magnetron etching apparatus.

[Prior Art] Conventionally, as a magnetic field forming method in a magnetron etching apparatus, an electromagnetic coil type and a permanent magnet type are known.

In principle, the electromagnetic coil type magmetron etching apparatus is constructed as shown in FIG. 6 of the accompanying drawings. That is, as shown in FIG. 6, a high frequency power source C is connected to one of the electrodes A and B arranged opposite to each other so that a high frequency discharge is generated between these parallel plate electrodes. Helmholtz coils D and E whose magnetization directions are aligned are arranged in pairs on both left and right sides of B, and an alternating current is applied to these coils from an AC power source F to generate an alternating magnetic field on a substrate G.

Since the generated alternating magnetic field and the high frequency electric field are orthogonal to each other, electrons are confined in the vicinity of the etching electrode A, and high-density plasma can be formed. That is, in FIG. 7, the magnetic field is generated toward the front or back direction perpendicular to the plane of the drawing, and the electric field vibrates between the electrodes, that is, in the vertical direction. In the combined electromagnetic field of these magnetic and electric fields, the electrons drift to the right when the direction of the magnetic field is I, and to the left when the direction of the magnetic field is II. The glow discharge generated by the electrons can be present at a uniform concentration on the electrodes.

[Problems to be Solved by the Invention] By the way, in the above-mentioned conventional electromagnetic coil type magnetron etching apparatus, since an alternating magnetic field is used, the strength of the magnetic field changes with time, and a discharge for generating plasma is generated. The voltage will change greatly. For example, the frequency of the alternating magnetic field is 50Hz and the frequency of the high frequency power supply is 13.56M.
At Hz, the discharge voltage becomes as shown in FIG. As can be seen from this figure, the discharge voltage strongly depends on the alternating magnetic field strength, and when the magnetic field is 0 gauss, the discharge voltage becomes maximum, and as a result, the energy of the ions colliding with the substrate becomes maximum and ion damage becomes a problem. Become. That is, in the conventional device, since the discharge voltage for maintaining the plasma changes greatly, there is a problem that ion damage may occur when the discharge voltage is high.

Therefore, an object of the present invention is to provide a rotating magnetic field type magnetron etching apparatus capable of always performing dry etching with a relatively low discharge voltage in order to solve the above problems.

[Means for Solving the Problems] In order to achieve the above-mentioned object, a rotating magnetic field type magnetron etching apparatus according to the present invention includes an etching electrode in a vacuum container, and the etching electrode and the periphery of the etching electrode at right angles to each other. The two pairs of electromagnetic coil devices arranged and the coils of each pair of the above two pairs of electromagnetic coil devices are supplied with currents with a 90 ° phase shift, and the electromagnetic coil device is rotated in parallel with the surface of the etching electrode. An alternating current power supply for generating a magnetic field is provided.

A plurality of electromagnetic coil devices that generate a magnetic field that is parallel to the surface of the electrodes and that rotates can consist of two pairs of electromagnetic coils arranged at right angles to each other, in which case each pair of coils has a 90 ° angle. Phase-shifted currents flow.

In one form of the present invention, each of the two pairs of electromagnetic coil devices that generate a rotating magnetic field parallel to the surface of the electrode includes a magnetic pole portion disposed around the electrode and an iron core portion around which the coil is wound. And can be provided.

Further, according to one aspect of the present invention, each of the plurality of electromagnetic coil devices that generate a rotating magnetic field parallel to the surface of the electrode includes a magnetic pole portion arranged around the electrode and an iron core portion around which the coil is wound. And can be provided.

[Operation] In the operation of the apparatus of the present invention configured as described above, each electromagnetic coil device provided around the electrode is energized by an electric current having a predetermined phase angle different from that of an adjacent electromagnetic coil device. The magnetic field vector on the surface of the electrode shows as if the motion of the rotation vector, a stable magnetic field is formed on the surface of the electrode, and the discharge voltage is stable and can be kept relatively low. Further, the plasma formed by the discharge does not become unevenly distributed due to the rotating magnetic field, and can be made uniform and averaged.

[Embodiment] An embodiment of the present invention will be described below with reference to FIGS. 1 to 5 of the accompanying drawings.

1 and 2 schematically show the configuration of the main part of a rotating magnetic field type magnetron etching apparatus according to an embodiment of the present invention, in which reference numeral 1 denotes a disk-shaped etching electrode which faces the electrode 2 and is parallel to each other. It is located in. Etching electrode 1
Supports the substrate 3 to be etched and is connected to a high frequency power supply 4. As shown in FIG. 2, two pairs of electromagnetic coils 5a, 5b and 6a, 6b are arranged around these electrodes 1, 2 at right angles to each other. Each pair of electromagnetic coils 5a, 5b and 6a, 6b is composed of, for example, an air-core Helmholtz coil and is connected to different AC power supplies 5c and 6c, respectively, and these AC power supplies 5c and 6c respectively supply currents 90 ° out of phase with each other. The alternating magnetic fields B1 and B2 are generated by supplying them to a pair of electromagnetic coils which are combined with each other, whereby the magnetic field B1 generated by the electromagnetic coils 5a and 5b of one pair and the electromagnetic coils 6a and 6b of the other pair are generated. Combined magnetic field B2 with the generated magnetic field B2
As shown in FIG. 2, the magnetic field vector on the surface of the electrode becomes as if it were a motion of the rotation vector.

The temporal changes in the magnetic field strength on the electrode surface due to the AC power E1, E2 from the AC power supplies 5c, 6c for each pair of electromagnetic coils 5a, 5b and 6a, 6b are shown in FIG. As described above, the change in magnetic field strength is small and almost constant, and as a result, the discharge voltage for generating plasma can be stable.

4 and 5 schematically show a modified embodiment of the present invention. In this case, in order to save the magnetizing current, a cross-shaped iron yoke 6 and magnetic pole pieces P1 to P4 at the tip of each yoke are formed. And the magnetic pole pieces P1 to P4 are positioned around the etching electrode 7 so as to reduce the gap length. Each of the electromagnetic coils C1 to C4 is wound around a cross-shaped iron yoke 6 as shown in FIG. 5, and the electromagnetic coils C1, C2 and C3, C4 which are diametrically opposed to each other are shown in FIGS. 1 and 2. Similar to the case of the embodiment, they are respectively connected to two different AC power supplies (not shown) which supply currents which are 90 ° out of phase with each other. In this case, a silicon steel plate can be preferably used as the iron core material in order to reduce the distortion rate of the magnetic field waveform.

By the way, in the illustrated embodiment, the case where four electromagnetic coils are used to form the rotating magnetic field has been described, but naturally the number of electromagnetic coils can be increased by appropriately selecting the phase of the alternating current supplied to each coil. It is also possible to form three or four or more to form a rotating magnetic field.

Also, if a sputter target is placed on the electrode instead of the substrate, it can be used as a magnetron buttering cathode and the use efficiency of the target can be improved. Further, in the illustrated embodiment, it is possible to dispose the substrate on the counter electrode and use it as plasma CVD.

[Effects of the Invention] As described above, according to the present invention, a plurality of electromagnetic coil devices are provided around an electrode, and each adjacent electromagnetic coil device is excited by an alternating current having a phase shift to generate an electrode. Since it is configured to form a rotating magnetic field on the surface, the discharge voltage can be kept relatively low, etching processing with less ion damage can be performed, and non-uniform plasma can be averaged. Therefore, the etching treatment with high uniformity can be performed.

[Brief description of drawings]

FIG. 1 is a schematic front view of a main part of a rotating field type magnetron etching apparatus according to an embodiment of the present invention, FIG. 2 is a plan view in which a part of the apparatus of FIG. 1 is omitted, and FIG. A graph showing changes in the rotating magnetic field by the apparatus shown in FIG. 2, FIG. 4 is a perspective view schematically showing a modified embodiment of the present invention, and FIG. 5 is an electromagnetic coil, an iron core and a pole piece in the apparatus of FIG. 6 is a schematic diagram of the structure of FIG. 6, FIG. 6 is a schematic diagram showing a conventional electromagnetic coil type magnetron etching apparatus, FIG.
FIG. 8 is an enlarged explanatory view showing the behavior of electrons on the electrodes in the device of FIG. 6, and FIG. 8 is a graph showing the relationship between the magnetic field strength and the discharge voltage in the device of FIG. In the figure 1, 2: electrodes 5a, 5b: a pair of electromagnetic coils 6a, 6b: a pair of electromagnetic coils 5c, 6c: AC power supply

Claims (2)

[Claims] 1. An etching electrode, two pairs of electromagnetic coil devices arranged at right angles to each other around the etching electrode in a vacuum container, and 90 ° phase for each pair of coils of the two pairs of electromagnetic coil devices. A rotating magnetic field type magnetron etching apparatus, which is provided with an alternating current power source for supplying a current deviated from the electromagnetic coil apparatus to generate a rotating magnetic field parallel to the surface of the etching electrode. 2. The rotating magnetic field type magnetron according to claim 1, wherein each of the two pairs of electromagnetic coil devices comprises a magnetic pole portion arranged around the electrode and an iron core portion around which the coil is wound. Etching equipment.