JPS6354727A - Ion beam etching system - Google Patents

Abstract

PURPOSE:To inhibit the diffusion of ion beams projected from an ion source, and to utilize ion beams effectively by installing a cylindrical compensating electrode between the ion source and a material to be etched. CONSTITUTION:A compensating electrode 14 for suppressing the diffusion of an ion current and compensating the ion current in the direction of focusing is mounted into an etching chamber 9 between an ion source 2 and a material to be etched 10. The compensating electrode 14 is constituted of a continuous wall body consisting of a non-porous material such as a metallic band material. Positive ions generated by the ion source 2 are accelerated toward the material to be etched 10 by an ion accelerating electrode 8. The accelerated positive ion current is reflected in the central direction by the compensating electrode 14 to which positive potential is applied by a power supply 15, and projected to the material to be etched 10 without being diffused. Since the compensating electrode 14 takes a conical shape, it compensates the ion current in the direction that the ion current is focussed effectively toward the material to be etched 10.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to an ion beam etching apparatus for patterning a semiconductor integrated circuit or the like by irradiating the surface of a semiconductor wafer or the like with an accelerated ion beam.

[Background of the Invention] Ion beam etching is used instead of chemical etching to etch fine patterns on the submicron order of semiconductor integrated circuits. This ion beam etching method uses ions generated by electron bombardment, which are accelerated with high voltage, to irradiate a sample (semiconductor wafer) placed in a vacuum, and utilizes the sputtering of surface atoms that originate from the ions. It is something. In such an ion beam etching system, it is necessary to efficiently irradiate the semiconductor wafer with the generated ions and effectively and uniformly etch the semiconductor wafer with a small diameter ion source, thereby reducing the size of the system. or desired.

[Prior Art] The configuration of a conventional ion beam etching apparatus is shown in FIG. Ions are generated in an ion source 2 having a thermionic emitting filament l. 3 is a power supply for the filament; 4 is a power supply for applying a potential to the filament with respect to the ion source;
5 is a power source for applying a potential to the entire ion source, and 7 is a magnetic coil. An ion acceleration electrode 8 is provided adjacent to the ion source 2 . 6 is a power source for the ion accelerating electrode. Etching chamber 9 facing ion acceleration electrode 8
A material to be etched 10 such as a semiconductor wafer is provided inside.
or placed. II has an exhaust port and is connected to a vacuum device (not shown).

Etching gas is introduced into the ion source 2 at a predetermined vacuum pressure, and thermionic electrons are generated from the thermionic emission filament l. The etching gas is ionized by collision with thermoelectrons, passes through the ion acceleration electrode 8, is accelerated by the electrode 8, becomes an ion beam, and irradiates the material 10 to be etched.

FIG. 5 shows a club for measuring the current density of ions irradiated onto the material to be etched in such a conventional ion beam etching apparatus. In the club, the horizontal axis represents the distance fax from the center of the material to be etched, and the vertical axis represents the ion current density. As can be seen from the graph, the ion current density decreases symmetrically from the center of the material to be etched radially outward. Therefore, the etching rate is large at the center of the material to be etched and becomes smaller as it moves away from the center. Therefore, in order to obtain a uniform etching rate over the entire surface of the material to be etched, it is necessary to use an ion source with a larger diameter than the material to be etched, and use only the part where the ion current density is uniform at the center of the ion flow. I had to. For this reason, there was a problem in that the ion source became large and the device became large.

[Object 1 of the Invention] The present invention has been made in view of the drawbacks of the prior art described above, and is aimed at correcting the ion beam by suppressing the diffusion of the ion beam irradiated from the ion source and correcting the ion beam in the direction of convergence. It is an object of the present invention to provide an ion beam etching device that effectively utilizes the diameter of an ion source to reduce its diameter.

[Example] FIG. 1 shows the configuration of an ion beam etching apparatus according to the present invention. In this embodiment, a correction electrode 14 is provided in the etching chamber 9 between the ions Kt 2 and the material to be etched 1O for suppressing the diffusion of the ion flow and correcting the ion flow in the direction of convergence. The correction electrode 14 is independently provided with an electrode 15 for applying a potential.

In this embodiment, a positive potential is applied to the correction type Th+4,
The ion beam of positive ions generated by the ion source 2 is focused toward the center and corrected. The correction electrode 14 has a conical cylindrical shape with its central axis in the ion beam irradiation direction, and the diameter reduction direction of the cone is directed toward the material to be etched IO. The correction electrode 14 is constituted by a rapidly extending wall made of a non-porous material such as a metal strip. Instead of the continuous wall, the correction electrode 14 may be constructed of a porous wall made of a porous plate, a wire mesh material, or the like.

In this case, particles whose direction cannot be controlled by the electrode, such as neutral particles, pass through this electrode, so that they are prevented from impacting the electrode, scattering their direction, and impinging on the material to be etched.

The structure and operation other than the ion flow correction electrode 14 are the same as the conventional structure shown in FIG. 4. Positive ions generated by the ion source 2 are accelerated by the ion accelerating electrode 8 toward the material to be etched lO. This accelerated positive ion flow is applied to a correction electrode 1 to which a positive potential is applied by a power source 15.
4 and irradiates the material 10 to be etched without being diffused. Furthermore, since the correction electrode 14 has a conical shape, it corrects the ion flow in a direction that effectively converges the ion flow toward the material 10 to be etched.

FIG. 2 shows another embodiment of the present invention, in which a power source 15 that applies a potential to the correction electrode 14 is electrically connected to a power source 5 that applies a potential to the ion source 2. Such a wiring structure makes it easy to set the potential of the correction electrode corresponding to the potential of the ion source. Other structures, functions, and effects are the same as those of the embodiment shown in FIG.

FIG. 3 shows yet another embodiment of the present invention, in which the correction electrode 1
A power source 15 that applies a potential to 4 or a heavy source 6 for the ion accelerating electrode
It is electrically connected to the interlocking LTf function. Such a wiring structure makes it easy to set the potential of the correction electrode corresponding to the potential of the ion accelerating electrode. Other structures, functions, and effects are the same as those of the embodiment shown in FIG.

[Effects of the Invention] As explained above, in the ion beam etching apparatus according to the present invention, since the cylindrical correction electrode is installed between the ion source and the material to be etched, the material to be etched from the ion source is The material to be etched is irradiated with good uniformity by preventing the diffusion of the ion flow. Therefore, by making the diameter of the ion source relative to the material to be etched smaller than in the past, the size of the etching apparatus can be reduced.

[Brief explanation of drawings]

FIGS. 1 to 3 are block diagrams of different embodiments of the present invention, FIG. 4 is a block diagram of the prior art, and FIG. 5 is a diagram of the ion current density of a conventional ion beam etching apparatus. . 2: Ion source, 5, 6. Is: power supply, 8: accelerating electrode, 9: etching chamber. 10: Material to be etched, 14: Correction electrode. Patent Applicant Canon Co., Ltd. Agent Patent Attorney Tatsuo Ito Agent Patent Attorney Satoshi Ito Kozutsu 1 Figure @ 2 Figure

Claims (1)

[Claims] 1. An ion source, an accelerating electrode that accelerates ions generated by the ion source, an etching chamber in which a material to be etched to be irradiated with the ions accelerated by the accelerating electrode is placed; An ion beam etching apparatus characterized by a correction electrode for correcting ion flow provided in an etching chamber. 2. The ion beam etching apparatus according to claim 1, wherein the correction electrode has a cylindrical shape having a central axis in the ion irradiation direction. 3. The ion beam etching apparatus according to claim 2, wherein the cylindrical correction electrode has a conical shape whose diameter decreases in the direction of the ion flow. 4. The ion beam etching apparatus according to any one of claims 1 to 3, wherein the correction electrode is constituted by a continuous wall made of a non-porous material. 5. The ion beam etching apparatus according to any one of claims 1 to 3, wherein the correction electrode is constituted by a porous wall made of a porous plate or a wire mesh material. 6. The ion beam etching apparatus according to any one of claims 1 to 5, characterized in that a correction electrode power source for applying a potential to the correction electrode is provided independently. 7. The correction electrode power source that applies a potential to the correction electrode is:
6. The ion beam etching apparatus according to claim 1, wherein the ion beam etching apparatus is electrically connected to a power source that applies a potential to the ion source. 8. The correction electrode power supply that applies a potential to the correction electrode is:
6. The ion beam etching apparatus according to claim 1, wherein the ion beam etching apparatus is electrically connected to a power source that applies a potential to the accelerating electrode. 9. Any one of claims 1 to 8, wherein a positive potential is applied to the correction electrode to correct the positive ion flow that has passed through the ion accelerating electrode in a direction of convergence. The ion beam etching apparatus described in Section 1.