JP5636931B2 - Electron beam irradiation apparatus, electron beam irradiation processing apparatus using the same, and collector electrode used therefor - Google Patents

Description

  The present invention relates to an electron beam irradiation apparatus, an electron beam irradiation processing apparatus using the same, and a collector electrode used therefor, and more specifically to an ion collector electrode of a neutralizer for a high frequency ion source.

  As a film forming technique for manufacturing a semiconductor device and an optical element, an apparatus is used in which a current is passed through a coiled antenna to generate plasma with an induced electric field, and an electron beam is extracted and irradiated.

  In the ion-assisted film deposition apparatus, if ions are continuously irradiated from the ion source to the target substrate, the ions cannot reach the film by the positively charged substrate and cannot be assisted. If the potential exceeds the tolerance, abnormal discharge occurs between the positively charged substrate and the other member, which causes film defects. For this reason, it is necessary to neutralize the substrate by irradiating the substrate with electrons from an electron beam irradiation device (neutralizer).

  As a conventional technique, an electron beam irradiation apparatus as shown in FIG. 3A is widely used. The electron beam irradiation apparatus 1 includes a gas inlet 2, a high frequency induction coil 3, a chamber 4, a collector electrode 5 (cathode electrode), a nut 6, a chamber plate 7, and a keeper electrode 8 (anode electrode). In some cases, a trigger electrode (not shown) is provided in the collector electrode for improving the ignitability of plasma, particularly for initial discharge.

  When an electron beam irradiation apparatus is used as a neutralizer, when a high frequency current is passed from a high frequency power source to a high frequency induction coil in a state where gas is introduced into the chamber 4 through the gas introduction port 2, a high frequency induction electric field is generated inside the chamber 4. Is generated and plasma is generated. When plasma is generated and a voltage is applied to the keeper electrode 8 so as to be more positive than the collector electrode 5, electrons in the plasma are attracted to the keeper electrode 8 side due to a potential difference between the collector electrode 5 and the keeper electrode 8. . The attracted electrons are extracted as an electron beam from a hole formed in the keeper electrode 8 and are irradiated onto a positively charged substrate.

  In the electron beam irradiation apparatus of FIG. 3A, the collector electrode 5 installed inside the chamber 4 made of an insulator acts as a shield against the induced electric field, so that the ignitability of the plasma is remarkably deteriorated. Many of the problems with high-frequency ion sources are that the electron beam irradiation device does not ignite. In order to ignite plasma, it is necessary to supply a high voltage to the high-frequency induction coil, and it is necessary to increase the current capacity of the high-frequency power source, as well as problems such as dielectric breakdown such as arc discharge and power failure. is there.

  The electron beam irradiation apparatus disclosed in Patent Document 1 includes: (1) a collector electrode made of a hollow, substantially cylindrical conductor having a space for focusing plasma and having a plurality of slits formed on its side surface; And (2) having a trigger electrode connected within the collector electrode for applying a high voltage for initial discharge.

JP 2003-242917 A

  However, even when a plurality of slit-like openings are provided in the collector electrode as in Patent Document 1, sufficient plasma ignitability cannot be ensured unless a high voltage is supplied from the trigger electrode. In addition, if the trigger electrode is installed, a new electrode and a power source different from the collector electrode and the keeper electrode are required, which complicates the apparatus configuration and increases the cost. Furthermore, since a plurality of slit-shaped openings are formed, there is a problem that the collector electrode is easily deformed.

  When a plurality of openings are provided in order to improve plasma ignitability, the emission current flowing through the collector electrode is reduced. The emission current represents the amount of emitted electrons and depends on the surface area of the collector electrode. The larger the surface area, the larger the emission current obtained. Accordingly, the plurality of openings reduce the amount of emitted electrons.

  Accordingly, an object of the present invention is to greatly reduce the high-frequency power required for ignition by increasing the ignitability of plasma. It is another object of the present invention to provide a collector electrode structure in which the obtained emission current is not impaired, an electron beam irradiation apparatus and an electron beam processing apparatus provided with the collector electrode structure.

  A first aspect of the present invention is an electron beam irradiation apparatus comprising a cylindrical collector electrode made of a conductor and a high-frequency induction coil wound around the collector electrode, and the collector electrode has an opening on the side surface. , An electron beam irradiation apparatus in which the opening is disposed corresponding to the high-voltage side end of the high-frequency induction coil.

  A second aspect of the present invention is a cylindrical collector electrode for an electron beam irradiation apparatus, which is disposed inside a high-frequency induction coil and is made of a conductor, and has an opening on the side, and the opening is the high-frequency induction coil. It is the collector electrode for electron beam irradiation apparatuses arrange | positioned corresponding to a high voltage | pressure side edge part.

According to a third aspect of the present invention, in the first and second side surfaces, the opening includes a first portion and a second portion extending in a longitudinal direction, and the first portion is a high-pressure side of the high-frequency induction coil. It arrange | positioned corresponding to an edge part and comprised so that the average opening width of a 1st part might become larger than the average opening width of a 2nd part.
Further, the maximum width of the first portion may be larger than the maximum width of the second portion, and the area of the opening is 5% or more and 20% or less with respect to the area of the collector electrode. It is preferable to configure.

  According to a fourth aspect of the present invention, there is provided an electron beam irradiation processing apparatus comprising: a vacuum chamber that maintains a vacuum inside; a substrate holding unit that holds a substrate in the vacuum chamber; and an electron beam irradiation apparatus according to the first and third aspects. is there.

It is a figure which shows the electron beam irradiation apparatus of the Example of this invention. It is a figure which shows the structure of the collector electrode and high frequency induction coil in FIG. 1A. It is a figure which shows the collector electrode in FIG. 1A. It is a figure which shows the modification of the collector electrode in FIG. 1A. It is a figure which shows the modification of the collector electrode in FIG. 1A. It is a figure which shows the electron beam irradiation processing apparatus containing the electron beam irradiation apparatus of this invention. It is a figure which shows the conventional electron beam irradiation apparatus. It is a figure which shows the collector electrode in FIG. 3A.

  Embodiments of the present invention will be described below with reference to the drawings. The embodiments described below are the most preferred examples of the present invention, and various modifications can be made within the scope of the gist of the present invention.

Example.
FIG. 1A is a diagram showing an electron beam irradiation apparatus according to an embodiment of the present invention, and FIG. 1B is a diagram showing a configuration of a collector electrode and a high-frequency induction coil in FIG. 1A. 1C is a view showing the collector electrode of FIG. 1A, and FIGS. 1D and 1E are views showing modifications of the collector electrode of FIG. 1A. 1A and 3A are the same except for the shape of the collector electrode.

As shown in FIG. 1A, the electron beam irradiation apparatus 11 includes a gas inlet 12, a high frequency induction coil 13, a chamber 14, a collector electrode 15 (cathode electrode), a nut 16, a chamber plate 17, and a keeper electrode 18 (anode electrode). It consists of
The principle of electron beam irradiation is that when a high-frequency current is passed from a high-frequency power source to a high-frequency induction coil in a state where gas is introduced into the chamber 14 through the gas inlet 12, a high-frequency induction electric field is generated inside the chamber 14 and plasma is generated. Will occur. When plasma is generated and a voltage is applied to the keeper electrode 18 so as to have a positive potential with respect to the collector electrode 15, electrons in the plasma are attracted toward the keeper electrode 18 due to a potential difference between the collector electrode 15 and the keeper electrode 18. The attracted electrons are extracted as an electron beam from a hole formed in the keeper electrode 18.

  The gas inlet 12 is for introducing a gas for generating plasma into the chamber 14. For example, argon (Ar) gas is used as the plasma generating gas.

  The chamber 14 is not limited to being in contact with the high frequency induction coil 13 and the collector electrode 15 as long as the high frequency induction coil 13 and the collector electrode 15 are separated and insulated.

  The keeper electrode 18 is used to extract electrons from the plasma in the collector electrode 15 when a voltage is applied, and is formed of a known material used for the electrode. The gas inlet is fixed in the collector electrode 15 with the nut 16, and the whole is fixed by being connected to the chamber 14 with the chamber plate 17.

  The high-frequency induction coil 13 is a high-frequency radio wave radiator and is wound around the collector electrode 15 via the chamber 14. As shown in FIG. 1B, the high voltage side end of the high frequency induction coil 13 is connected to a high frequency power source 19, and the low voltage side end of the high frequency induction coil 13 is grounded. A device that controls the high-frequency induction coil 13, a capacitor, and the like may be connected therebetween.

  The collector electrode 15 focuses the generated plasma and controls the amount of the electron beam to extract the electron beam, and is formed from a known material used for the electrode. For example, nickel (Ni) is used as a known material. The collector electrode 15 has an opening on the side surface, and the opening is disposed corresponding to the high-voltage side end of the high-frequency induction coil 13 as shown by the dotted line portion in FIG. If the collector electrode 15 has a space inside, the shape is not necessarily cylindrical (for example, a polygonal column).

  Since the low voltage side end of the high frequency induction coil 13 is grounded, the electric field at the high voltage side end of the high frequency induction coil 13 is the highest. That is, it is possible to strengthen the capacitive coupling of the high frequency induction electric field by opening only the lower part of the collector electrode 15 corresponding to the position where the voltage applied to the high frequency induction coil 13 is the highest, so that the capacitive coupling of the high frequency induction electric field can be strengthened. The ignitability can be improved and the amount of emission current obtained can be prevented from decreasing.

In the inductively coupled plasma as in this configuration, capacitive coupling due to the coil electric field is dominant in the ignition to low plasma density region, and then there is a mode jump that shifts to the inductive coupling mode as the density increases.
In other words, since the ignition of such a plasma generator causes capacitive coupling of the coil electric field, combining the high-voltage side end of the high-frequency induction coil with the opening of the collector electrode improves the plasma ignitability and further increases the opening. It becomes possible to ignite reliably by widening the width of the part.

For the following three collector electrodes, an experiment was conducted to verify the ignitability of plasma at the collector electrode opening and the position of the high frequency induction coil. Electric power that can be ignited under the following conditions was measured and compared.
(1) When the opening is not formed (when the collector electrode of FIG. 3B is configured as shown in FIG. 1B), (2) When the opening is formed so as to correspond to the low voltage side end of the high frequency induction coil (FIG. 1B collector electrode is turned upside down), and (3) the opening is formed so as to correspond to the high voltage side end of the high frequency induction coil (when configured as shown in FIG. 1B). The gas flow rate was kept constant at 20 sccm. The results are shown in Table 1.

As shown in Table 1, in the case of (3), it was recognized that ignition was performed with a small amount of electric power. In other words, it has been found that the ignitability of the plasma is greatly improved by making the opening of the collector electrode correspond to the high voltage side end of the high frequency induction coil.

  When the area of the opening was 5% or more and 20% or less of the area of the collector electrode, a sufficient improvement in plasma ignitability was observed. Further, if the opening of the collector electrode is made to correspond to the high-voltage side end of the high frequency induction coil, the shape of the opening is not limited. For example, as shown in FIG. 1E, the shape of the opening is circular. Even if it exists, the same effect is acquired.

  Since the collector electrode has sufficient plasma ignitability, the electron beam irradiation apparatus can be operated without requiring a trigger electrode in the collector electrode. Therefore, problems such as dielectric breakdown due to high voltage supply can be prevented, the device configuration can be simplified, and the cost can be reduced.

  Also, by making the collector electrode opening correspond to the high-voltage side end of the high-frequency induction coil, it is possible to suppress a reduction in emission current caused by forming a plurality of slits in the collector electrode and reducing the surface area of the collector electrode. I can do it. That is, not only can the plasma ignitability be improved efficiently, but also the emission current can be prevented from decreasing.

  As shown in the dotted line part of FIG. 1B, another aspect of the present invention has an opening made of a first part and a second part extending in the longitudinal direction on the side surface of the collector electrode. Is arranged corresponding to the high-voltage side end of the high-frequency induction coil, and the average opening width of the first part is larger than the average opening width of the second part.

  As described above, since the lower portion of the collector electrode 15 corresponding to the position where the voltage applied to the high frequency induction coil 13 is the highest is opened moderately, the capacitive coupling of the high frequency induction electric field can be strengthened. Plasma ignitability is improved. That is, the ignitability of plasma is improved by forming the opening corresponding to the first portion.

  However, if a plurality of openings corresponding to the second part are formed in a slit shape, the amount of emission current is greatly reduced, so the average opening width of the second part is the average opening of the first part. It is desirable to form it smaller than the width to suppress a decrease in the amount of emission current.

  If the first part of the opening of the collector electrode is made to correspond to the high-voltage side end of the high-frequency induction coil, the shape of the first part and the second part of the opening is not limited. The same effect can be obtained even with the shape of the opening as shown in FIGS. 1D and 1E.

  Since the collector electrode has sufficient plasma ignitability, the electron beam irradiation apparatus can be operated without requiring a trigger electrode in the collector electrode.

  Further, the first portion of the collector electrode opening is concentrated on the high-voltage side end of the high-frequency induction coil, and the second electric field is sufficiently introduced into the collector electrode from a direction different from the direction in which the electron beam is extracted. By forming the portion, it is possible to suppress a reduction in emission current caused by forming a plurality of slits in the collector electrode and reducing the surface area of the collector electrode, and to further improve the ignitability of plasma.

  FIG. 2 is a diagram showing an electron beam irradiation processing apparatus having the electron beam irradiation apparatus of the present invention. The electron beam irradiation processing apparatus 21 is provided with a vacuum chamber 22, a substrate holding unit 23, an electron beam irradiation apparatus 24, a charged particle irradiation apparatus 25, and the like.

  As shown in FIG. 2, the electron beam irradiation device 24 is installed to irradiate a target 26 such as a substrate, and corresponds to the electron beam irradiation device of the present invention. The charged particle irradiation device 25 is also installed so as to irradiate a target 26 such as a substrate, and the electron beam irradiation device 24 neutralizes the charged particles. The vacuum chamber 22 is connected to a vacuum pump (not shown) so that the inside of the vacuum chamber 22 is evacuated. The substrate holding unit 23 holds the target 26 in the vacuum chamber, and may be formed independently, or in conjunction with the charged particle irradiation apparatus and the electron beam irradiation apparatus via the control unit 27. Also good.

  By using such an electron beam irradiation processing apparatus, it is possible to carry out heating of a sample such as metal, removal of impurities, neutralization and the like while securing the benefits of the electron beam irradiation apparatus of the present invention.

1,11. Electron beam irradiation device 2, 12. Gas inlet 3, 13. High-frequency induction coils 4, 14. Chambers 5, 15. Collector electrodes 6, 16. Nuts 7, 17. Chamber plates 8, 18. Keeper electrode 19. High frequency power supply 21. Electron beam irradiation processing device 22. Vacuum chamber 23. Substrate holding means 24. Electron beam irradiation device 25. Charged particle irradiation device 26. Target 27. Control unit

Claims (9)

A cylindrical collector electrode made of a conductor and a high-frequency induction coil wound around the collector electrode,
The collector electrode has an opening on a side surface, and the opening is disposed corresponding to the high-voltage side end of the high-frequency induction coil. The electron beam irradiation apparatus according to claim 1.
The opening includes a first portion and a second portion extending in a longitudinal direction, the first portion is disposed corresponding to a high-voltage side end portion of the high-frequency induction coil, and the first portion An electron beam irradiation apparatus in which an average aperture width is larger than an average aperture width of the second portion. The electron beam irradiation apparatus according to claim 2,
An electron beam irradiation apparatus wherein the maximum width of the first portion is larger than the maximum width of the second portion. The electron beam irradiation apparatus according to claim 1 .
An electron beam irradiation apparatus in which the area of the opening is 5% or more and 20% or less with respect to the area of the collector electrode. A cylindrical collector electrode for an electron beam irradiation device disposed inside a high frequency induction coil and made of a conductor,
The collector electrode for electron beam irradiation apparatuses which has an opening part in a side surface and the said opening part is arrange | positioned corresponding to the high voltage | pressure side edge part of the said high frequency induction coil. The collector electrode of claim 5, wherein
The opening includes a first portion and a second portion extending in a longitudinal direction, the first portion is disposed corresponding to a high-voltage side end portion of the high-frequency induction coil, and the first portion A collector electrode having an average opening width larger than the average opening width of the second portion. The collector electrode of claim 6.
A collector electrode wherein the maximum width of the first portion is greater than the maximum width of the second portion. The collector electrode of claim 5 ,
The collector electrode whose area of the said opening part is 5% or more and 20% or less with respect to the area of a collector electrode. A vacuum chamber that maintains a vacuum inside,
Substrate holding means for holding the substrate in the vacuum chamber;
An electron beam irradiation device for irradiating the substrate;
The said electron beam irradiation apparatus is an electron beam irradiation processing apparatus which is an electron beam irradiation apparatus as described in any one of Claims 1 thru | or 4.

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