WO2013099044A1

WO2013099044A1 - Ion beam processing device and neutralizer

Info

Publication number: WO2013099044A1
Application number: PCT/JP2012/002921
Authority: WO
Inventors: 翼深石; 行人中川; 公志辻山
Original assignee: キヤノンアネルバ株式会社
Priority date: 2011-12-28
Filing date: 2012-04-27
Publication date: 2013-07-04
Also published as: JP2015088218A

Abstract

The invention provides an ion beam processing device and a neutralizer that are capable of reducing a fall of a deposit that has accumulated on an anode of the neutralizer due to sputtering of a cathode of the neutralizer caused by plasma generated in the neutralizer, said fall being from the anode. The ion beam processing device of one embodiment of the invention is provided with: a structure that irradiates the interior of a processing chamber with an ion beam generated in a plasma generation chamber; and a neutralizer that discharges electrons. The neutralizer is characterized by comprising the cathode, the anode, a voltage application means, and a gas supply section, and the anode and the cathode being formed from materials that have the same thermal expansion ratio. The cathode has mutually facing portions, and the plasma is generated in a space between the mutually facing portions. The anode has an opening for extracting electrons from the plasma formed in the space. The voltage application means is a means for applying a positive voltage to the anode and extracting electrons from the plasma, and applying a voltage that is negative relative to the positive voltage to the cathode and generating the plasma. The gas supply section is a section for supplying discharge gas to the space.

Description

Ion beam processing device and neutralizer

The present invention relates to an ion beam processing apparatus and a neutralizer, and more particularly to a neutralizer as an electron gun and an ion beam processing apparatus including the neutralizer.

In the manufacture of electronic parts, various treatments using ion beams are applied. In particular, ion beam etching using an ion beam for etching is widely used for processing a substrate to be processed.

An ion beam is formed by extracting positive ions from a plasma source using a plurality of electrodes. At this time, in order to prevent the substrate to be processed from being charged up, it is necessary to supply a negative charge corresponding to the charge amount of the extracted ion beam. The negative charge is supplied by supplying electrons using a neutralizer (see Patent Document 1).

JP-A-4-351538

The neutralizer is an electron generator installed to neutralize the electric charge generated by the ion beam in the ion beam processing apparatus, and an example of the structure is a hollow cathode type as shown in FIG. It is done. A hollow cathode type neutralizer has a longer life than a neutralizer using a filament, and a large current density and efficiency can be obtained with a small plasma volume. 3 and 4 are diagrams created by the present inventor for explaining the problems of the conventional neutralizer.

In FIG. 3, reference numeral 201 denotes an anode (anode), reference numeral 202 denotes a cathode (cathode), and reference numeral 203 denotes an insulator for insulating the anode 201 and the cathode 202. The cathode 202 has a cylindrical shape, and one end of the cathode 202 is open and the other end is closed. An opening formed at one end of the cathode 202 faces the anode 201. The cathode 202 has a hollow portion 207 in which plasma is formed. The cross-sectional shape of the hollow portion of the cathode 202 is generally circular, but it is sufficient that a space where plasma can be formed exists, such as a regular octagon or a regular hexagon. The anode 201 and the cathode 202 are connected to a power source 206 in order to apply a predetermined voltage to each. Reference numeral 204 denotes a gas introduction path for introducing discharge gas into the neutralizer, and reference numeral 205 denotes a gas introduction control unit for controlling the flow rate and pressure of the discharge gas introduced into the gas introduction path 204. Yes, connected to a gas source (not shown).

Plasma is formed in the hollow portion 207 by introducing a discharge gas into the neutralizer through the gas introduction path 204 and applying a negative voltage to the cathode 202 by the power source 206. Further, when a positive voltage is applied to the anode 201 by the power source 206, electrons are extracted from the plasma from the opening of the anode 201 facing the hollow portion 207, and the ion beam is neutralized.
For example, titanium is preferably used for the anode 201 in consideration of heat resistance, and stainless steel is preferably used for the cathode 202 in consideration of processability and cost.

In the hollow cathode type neutralizer as described above, the vicinity of the opening of the cathode 202 is scraped (sputtered) by ions in the plasma. The portion scraped from the cathode 202 by the plasma is deposited in the vicinity of the opening of the anode 201 inside the neutralizer, as shown in FIG. For this reason, when an ion beam is used in the manufacture of electronic components, the deposit 208 in the neutralizer falls on the substrate during processing to generate particles, resulting in product defects and a decrease in yield. Arise.

The present invention has been made in view of such problems, and the object of the present invention is that the cathode of the neutralizer is sputtered by ions in the plasma generated in the neutralizer. An object of the present invention is to provide an ion beam processing apparatus and a neutralizer capable of reducing the fall of deposits deposited on the anode of the neutralizer from the anode.

The gist of the present invention is that, in a neutralizer as an electron gun provided in an ion beam processing apparatus, the anode and the cathode are made of the same material or the same material.

According to a first aspect of the present invention, there is provided a plasma forming chamber having an internal space, a processing chamber connected to the plasma forming chamber, power supply means for forming plasma in the plasma forming chamber, and the plasma forming chamber. An ion beam processing apparatus comprising: extraction means for extracting ions from a formed plasma and irradiating an ion beam toward the processing chamber; and a neutralizer provided in the processing chamber and emitting electrons. The neutralizer has opposed portions, a cathode in which plasma is generated in a space between the opposed portions, and an anode having an opening for extracting electrons from the plasma formed in the space And applying a positive voltage to the anode to extract the electrons from the plasma, and applying a voltage negative to the positive voltage to the cathode. It has a voltage application means for generating plasma and a gas introduction part for introducing a discharge gas into the space, and the anode and the cathode are made of a material having the same thermal expansion coefficient. And

According to a second aspect of the present invention, there is provided a neutralizer having opposed portions, a cathode in which plasma is generated in a space between the opposed portions, and electrons from the plasma formed in the space. An anode having an opening for extracting the positive electrode; and applying a positive voltage to the anode to extract the electrons from the plasma; and applying a negative voltage to the positive electrode to the cathode It has a voltage application means for generating and a gas introduction part for introducing a discharge gas into the space, and the anode and the cathode are made of a material having the same thermal expansion coefficient. .

According to the present invention, the plasma generated in the neutralizer is etched at the cathode of the neutralizer, thereby reducing the deposits deposited on the anode of the neutralizer from the anode. it can. Therefore, by using the present invention, even when an ion beam is used for processing an electronic component, the generation of particles from the neutralizer is reduced and the yield is improved.

It is a figure for demonstrating an example of the ion beam processing apparatus which concerns on one Embodiment of this invention. It is a figure for demonstrating the neutralizer which concerns on one Embodiment of this invention. It is a figure for demonstrating the conventional neutralizer. It is a figure for demonstrating the problem of the conventional neutralizer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited to this embodiment, In the range which does not deviate from the summary, it can change suitably. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof may be omitted.

FIG. 1 shows a schematic diagram of an ion beam etching apparatus as an example of an ion beam processing apparatus using a neutralizer according to an embodiment of the present invention.

The ion beam etching apparatus 100 includes a plasma forming chamber 102 in which mainly plasma is formed, and a processing chamber 101 connected to the plasma forming chamber 102. The plasma forming chamber 102 is a plasma forming means for forming plasma, a bell jar 104 as a discharge vessel, a gas introduction unit 105, an antenna 106 that generates an induced magnetic field in the bell jar 104, and a high frequency power (source power) to the antenna 106. A discharge power supply 112, a matching unit 107 provided between the discharge power supply 112 and the antenna 106, and an electromagnetic coil 108. In addition, the plasma formation chamber 102 has a grid 109 installed at the boundary with the processing chamber 101. That is, the ion beam etching apparatus 100 is configured such that high-frequency power supplied from the discharge power source 112 is supplied to the antenna 106 and plasma is formed in the plasma formation chamber 102 inside the bell jar 104. The bell jar 104 includes a Faraday shield 118 on its inner wall.

An exhaust pump 103 is installed in the processing chamber 101. The processing chamber 101 has a substrate holder 110, and the substrate 111 is held by the substrate holder 110. After the plasma is formed in the plasma formation chamber 102, the ion beam etching apparatus 100 applies a voltage to the grid 109 to extract ions in the plasma formation chamber 102 as a beam. The substrate 111 is etched by the extracted ion beam. The substrate 111 charged by the ion beam is electrically neutralized by electrons emitted from the neutralizer 113.

FIG. 2 shows a hollow cathode type neutralizer 113 according to an embodiment of the present invention. The basic structure of the neutralizer 113 according to this embodiment may be the same as that of the hollow cathode type neutralizer shown in FIGS.
In FIG. 2, the neutralizer 113 has a cylindrical shape having a hollow portion 17, and includes a cathode 12 having a circular cross section. Since the inner wall of the hollow cathode 12 is configured to form the hollow portion 17, the other portion of the inner wall is present at a position where any portion of the inner wall faces each other. That is, the space between the mutually facing portions of the inner wall of the cathode 12 becomes the hollow portion 17. The cross-sectional shape is not limited to a circular shape, and may be any shape such as a regular octagonal shape or a regular hexagonal shape as long as plasma can be generated in the hollow portion 17. One end of the cathode 12 is open and the other end is closed. That is, an opening 12 a that connects the outside and the hollow portion 17 is formed at one end of the cathode 12. The neutralizer 113 is further provided with a plate-like anode 11a provided opposite to the opening 12a and having an opening 11b, and a cylindrical base 11c connected to the anode 11a. One end of the substrate 11c is opened, and the anode 11a is disposed in the opening. Further, a cathode 12 is provided inside the base 11c so as to face the anode 11a. Note that the anode 11a and the base 11c may be separate members or may be integrated.

In the base body 11c, an insulator 13 for insulating the anode 11a, the base body 11c, and the cathode 12 is provided. The neutralizer 113 includes a gas introduction path 14 for introducing a discharge gas into the neutralizer 113. That is, the gas introduction path 14 is a plasma forming space (for example, including the hollow portion 17 between the anode 11a and the cathode 12 in which plasma is formed by applying a voltage to the anode 11a and the cathode 12 in the neutralizer 113. It is provided so as to supply the discharge gas to the space between them. The gas introduction unit 14 includes a mass flow controller (MFC) and a valve, and is connected to a gas introduction control unit 15 for controlling the flow rate and pressure of the discharge gas introduced into the gas introduction path 14.

Furthermore, the neutralizer 113 further includes a power source 16 that applies a positive voltage with respect to the ground voltage to the anode 11a, and applies a negative voltage to the cathode 12 with respect to the positive voltage. In the present embodiment, when a predetermined voltage is applied to the cathode 12 by the power supply 16, plasma is generated in the hollow portion 17 as a space between the opposed portions of the cathode 12, and the plasma is generated on the anode 11 a by the power supply 16. Is applied, the plasma is maintained and electrons can be extracted from the plasma. The anode 11a and the cathode 12 are provided so as to extract electrons from the plasma to the outside through the opening 11b. In the present embodiment, the voltage applied to the cathode 12 may be a negative voltage with respect to the positive voltage applied to the anode 11a as described above, and the positive voltage applied to the anode 11a. The voltage may be lower than that. Therefore, the sign may be a negative voltage, or the sign may be a positive voltage but a voltage lower than the positive voltage applied to the anode.

In this embodiment, the anode 11a and the cathode 12 of the neutralizer 113 are materials having the same thermal expansion coefficient.

In the present embodiment, with such a configuration, when the discharge gas is introduced into the neutralizer 113 from the gas introduction path 14, the discharge gas is supplied to the plasma forming space (particularly, the hollow portion 17). At the same time, when a predetermined voltage is applied from the power source 16 to the anode 11a and the cathode 12, plasma is generated in the plasma forming space, and electrons are attracted to the anode 11a from the plasma and neutralized through the opening 11b. The light is emitted to the outside of the vessel 113. At this time, the cathode 12 (particularly in the vicinity of the opening 12a) is sputtered by the action of the plasma generated in the hollow part 17, and a part of the sputtered cathode 12 is applied to the anode 11a (particularly in the vicinity of the opening 11b). Deposits may form deposits 18.

However, when the anode 11a and the cathode 12 are materials having the same thermal expansion coefficient as in the present embodiment, the deposit 18 is formed by particles sputtered from the cathode 12, and therefore the anode 11a and the deposit The thermal expansion coefficient with 18 is also equal. For this reason, even if the anode 11a and the deposit 18 are heated by the plasma generated in the neutralizer 113, the amounts of thermal expansion are equal, and the stress generated at the interface between the anode 11a and the deposit 18 is greatly reduced. Is done. For this reason, even if the deposit 18 accumulates on the anode 11a, the deposit 18 hardly falls on the substrate 111, and particles can be reduced.
In the present specification, the term “particle” refers to a fine particle having a diameter of approximately 0.01 μm or more and 1 μm or less made of metal or a material containing metal.

In this embodiment, when the anode 11a and the cathode 12 are made of the same material, it is possible to further reduce particles. That is, since the materials of the anode 11a and the deposit 18 are the same, the adhesion between the anode 11a and the deposit 18 is improved, so that the risk of the deposit 18 falling on the substrate 111 is further increased. This can be further reduced.

When the anode 11a and the cathode 12 are made of the same material, titanium, molybdenum, tantalum or the like may be used. In particular, titanium is preferable from the viewpoint of low sputtering rate, high discharge efficiency, and the like.

From the viewpoint of low sputtering rate, conductive ceramics can be used as the material of the anode 11a and the cathode 12. In particular, materials such as silicon carbide, titania, and zirconia are relatively easy to impart conductivity, and can be used as an anode and a cathode.

In the present embodiment, the neutralizer 113 is an electron gun that emits electrons for electrically neutralizing the ion beam emitted from the plasma forming chamber 102, and is obtained by being sputtered from the cathode 12. It is not an apparatus intended to emit elements (eg, sputtered particles, ions of the sputtered particles, deposits 18 etc.). In particular, it is not desirable to discharge the deposit 18 from the neutralizer 113. Conventionally, as described with reference to FIG. 4, the reason why the deposit 208 deposited on the anode 201 is released from the neutralizer is that the deposit 208 is peeled off from the anode. In contrast, in the present embodiment, the anode 11a and the cathode 12 are made of the same material, for example, so that the thermal expansion coefficient of the anode 11a and the thermal expansion coefficient of the cathode 12 are the same. The amount of thermal expansion between the anode 11a and the deposit 18 can be made substantially equal, and the deposit 18 can be prevented from peeling off from the anode 11a due to the temperature change.

In the present embodiment, the cathode 11 side portion of the anode 11a is made of a material having the same thermal expansion coefficient as that of the cathode 12a, and the other portions are made of materials other than the material having the same thermal expansion coefficient as that of the cathode 12. Also good. In the present invention, as described above, it is essential to make the thermal expansion amounts of the deposit 18 derived from the cathode 12 and the anode 11a formed by the plasma substantially equal even if the temperature changes. Therefore, in the anode 11 a, at least the portion facing the cathode 12 may be a material having the same thermal expansion coefficient as that of the cathode 12. For example, the portion of the anode 11a facing the cathode 12 and the opening may be made of a material having the same thermal expansion coefficient as that of the cathode 12, and the portion of the anode 11a not facing the plasma may be made of another material.

In this embodiment, a hollow cathode type neutralizer has been described, but the present invention is not limited to this form. In the present invention, in the neutralizer that draws and emits electrons from the plasma generated in the neutralizer having an anode having an opening for emitting electrons to the outside and a cathode, the plasma sputters the cathode. It is important to reduce the falling of the deposit formed on the anode by depositing the sputtered particles generated as a part of the cathode on the anode. For example, a flat plate electrode as an anode having an opening as an electron emission port of a neutralizer is provided. Two flat plate electrodes as cathode electrodes for applying a negative voltage to the anode are arranged opposite to each other. An anode electrode is provided on the side of the two cathode electrodes arranged opposite to each other. The plasma may be generated in a space formed between the facing cathode electrodes, and electrons may be emitted from the plasma to the outside through the opening of the anode. In this embodiment, the cathode is two plate electrodes arranged opposite to each other as opposed portions of the cathode. Therefore, plasma is generated in the space between the two plate electrodes arranged opposite to each other by applying a predetermined voltage to the cathode. The anode preferably faces a space where plasma is generated.

However, in the present embodiment, by applying the hollow cathode type neutralizer 113, it is possible to generate high-density plasma at a low voltage in the neutralizer 113 while making the inside of the processing chamber 101 a high vacuum. . That is, even if the pressure of the discharge gas in the neutralizer 113 is lowered, a sufficient amount of electrons can be emitted from the neutralizer 113. Therefore, a good process can be performed even for a process that requires a high vacuum process such as fine processing of the MRAM.

(Example)
An example of processing an electronic component by ion beam etching using the neutralizer 113 according to this embodiment will be described below.

First, the processing chamber 101 and the plasma forming chamber 102 are exhausted by the exhaust pump 103. Next, the substrate 111 is placed on the substrate holder 110, and then Ar as a discharge gas is introduced into the plasma forming chamber 102 from the gas introduction unit 105 at 10 sccm.

Next, plasma is formed in the plasma formation chamber 102 by applying 1 kW of power to the antenna 106. Thereafter, a voltage is applied to the grid 109. The grid 109 has three electrodes. When viewed from the plasma forming chamber 102 side, a voltage of +200 V is applied to the first electrode, and a voltage of −800 V is applied to the second electrode. The third electrode is grounded. An ion beam is extracted from the plasma forming chamber 102 to the processing chamber 101 from the grid 109. The processing chamber 101 is evacuated to about 1.0 × 10 ⁻² Pa by the exhaust pump 103.

At this time, electrons are supplied to the ion beam from the neutralizer 113 in order to neutralize the ion beam extracted from the grid 109. Both the cathode 12 and the anode 11a of the neutralizer 113 are titanium. First, the discharge gas is introduced into the neutralizer 113 through the gas introduction controller 15 from the gas introduction path 14 at 5 sccm. Ar is used as the discharge gas. A voltage is applied to the cathode 12 of the neutralizer 113 so that the potential difference with respect to the anode 11a becomes −200 V, and plasma is formed in the hollow portion 17 of the cathode 12. A voltage of + 24V is applied to the anode 11a with respect to the ground potential, and electrons are mainly extracted from the plasma formed in the hollow portion 17 and emitted toward the substrate 111 through the opening portion 11b.

In the above-described examples, the ion beam etching apparatus has been described. However, the neutralizer according to the present embodiment can be applied to other ion beam apparatuses such as a surface modification apparatus and an ion beam sputtering apparatus. . Moreover, the ion beam processing apparatus using the neutralizer according to the present embodiment can be applied to fine processing of various electronic components.

Claims

A plasma forming chamber having an internal space;
A processing chamber connected to the plasma forming chamber;
Power supply means for forming plasma in the plasma forming chamber;
Extraction means for extracting ions from the plasma formed in the plasma forming chamber and irradiating an ion beam toward the processing chamber;
An ion beam processing apparatus provided in the processing chamber and provided with a neutralizer that emits electrons,
The neutralizer is
A cathode having opposed portions, wherein plasma is generated in a space between the opposed portions;
An anode having an opening for extracting electrons from plasma formed in the space;
Voltage application means for applying a positive voltage to the anode to extract the electrons from the plasma, and applying a voltage negative to the positive voltage to the cathode to generate the plasma;
A gas introduction part for introducing a discharge gas into the space;
An ion beam processing apparatus, wherein the anode and the cathode are made of a material having the same thermal expansion coefficient.
The ion beam processing apparatus according to claim 1, wherein the cathode has a hollow portion corresponding to the space, and one end thereof is opened.
The ion beam processing apparatus according to claim 1, wherein the anode and the cathode are made of the same material.
The ion beam processing apparatus according to claim 3, wherein the anode and the cathode are titanium.
A cathode having opposed portions, wherein plasma is generated in a space between the opposed portions;
An anode having an opening for extracting electrons from plasma formed in the space;
Voltage application means for applying a positive voltage to the anode to extract the electrons from the plasma, and applying a voltage negative to the positive voltage to the cathode to generate the plasma;
A gas introduction part for introducing a discharge gas into the space;
The neutralizer characterized in that the anode and the cathode are made of a material having the same coefficient of thermal expansion.
The neutralizer according to claim 5, wherein the cathode has a hollow portion corresponding to the space, and one end is opened.
The neutralizer according to claim 5, wherein the anode and the cathode are made of the same material.
The neutralizer according to claim 7, wherein the anode and the cathode are titanium.