JP2015088218A - Ion beam processing apparatus and neutralizer - Google Patents

Abstract

When a hollow cathode type neutralizer is used, deposits are generated inside the neutralizer. When a neutralizer is used when an electronic component is manufactured by an ion beam, particles are generated by the deposit falling on the substrate during processing, resulting in product defects and a decrease in yield.
In order to neutralize an ion beam, a hollow cathode type neutralizer provided in an ion beam processing apparatus, wherein the anode and the cathode of the neutralizer are made of a material having the same coefficient of thermal expansion. It is configured.
[Selection] Figure 2

Description

  The present invention relates to an ion beam processing apparatus and a neutralizer.

  Various processes using an ion beam are applied in the manufacture of electronic components and the like. In particular, ion beam etching using an ion beam for etching is widely used for processing a substrate to be processed.

The ion beam is formed by extracting 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 equal to the charge amount of the extracted ion beam.
Neutralization of the ion beam is performed by supplying electrons to the ion beam using a neutralizer (see Patent Document 1).

Japanese Unexamined Patent Publication No. 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 its structure is a hollow cathode type as shown in FIG. Can be considered. The hollow cathode type 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, 201 is an anode (anode), 202 is a cathode (cathode), and 203 is an insulator for insulating the anode 201 and the cathode 202. The cathode 202 has a cylindrical shape, one end is opened facing the anode 201, and the other end is closed. The cathode 202 has a hollow portion 207 for forming plasma therein. The cross-sectional shape of the hollow portion of the cathode 202 is generally circular, but it is sufficient that there is a space where plasma can be formed, 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 a discharge gas into the neutralizer, and 205 denotes a gas introduction control unit for controlling the flow rate and pressure of the discharge gas, which is connected to a gas source (not shown).

Plasma is formed in the hollow portion 207 by introducing a discharge gas into the neutralizer and applying a negative voltage to the cathode 202. Further, by applying a positive voltage to the anode 201, electrons are extracted from the opening of the anode 201, 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 by plasma. As shown in FIG. 4, the scraped cathode 202 material is deposited near the opening of the anode 201 inside the neutralizer to form a deposit 208. 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 to solve such problems, and an object of the present invention is to provide a neutralizer suitable for manufacturing electronic components and the like.

  The gist of the present invention is that, in a hollow cathode type neutralizer provided in an ion beam processing apparatus, the anode and the cathode are made of a material having the same thermal expansion coefficient 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 having an extraction means for extracting ions from the formed plasma and irradiating an ion beam toward the processing chamber, and the processing chamber includes a neutralizer for emitting electrons, The neutralizer includes a cathode having a hollow portion where plasma is formed, an anode facing the cathode and extracting electrons from the plasma formed in the hollow portion, a negative voltage applied to the cathode, and a positive voltage applied to the anode. A voltage applying means for applying a voltage of 5 and a gas introducing part for introducing a discharge gas into the hollow part, wherein the anode and the cathode are the same Characterized in that it is composed of a material having a coefficient of expansion.

  A second aspect of the present invention relates to a neutralizer, a cathode having a hollow portion in which plasma is formed, an anode facing the cathode and extracting electrons from the plasma formed in the hollow portion, and the cathode A negative voltage, a voltage applying means for applying a positive voltage to the anode, and a gas introducing part for introducing a discharge gas into the hollow part, wherein the anode and the cathode are the same. It is made of a material having a coefficient of thermal expansion.

  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 suppressed, and the yield is improved.

It is a figure for demonstrating an example of the ion beam processing apparatus which can apply 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.

  Embodiments of the present invention will be described below 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 the neutralizer according to the present invention.

The ion beam etching apparatus 100 mainly includes a plasma forming chamber 102 in which plasma is formed, and a processing chamber 101 connected to the plasma forming chamber 102.
As plasma forming means for forming plasma in the plasma forming chamber 102, 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 high frequency power (source power) to the antenna 106. A discharge power supply 112 to be supplied, a matching unit 107 provided between the discharge power supply 112 and the antenna 106, and an electromagnetic coil 108 are installed, and a grid 109 is installed at the boundary with the processing chamber 101. The high frequency power supplied from the discharge power source 112 is supplied to the antenna 106, so that plasma is formed in the plasma forming 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. Further, a substrate holder 110 is provided in the processing chamber 101, and the substrate 111 is fixed by the substrate holder 110.
After the plasma is formed in the plasma forming chamber 102, a voltage is applied to the grid 109 to extract ions in the plasma forming chamber 102 as a beam. The extracted ion beam is electrically neutralized by the neutralizer 113 and irradiated onto the substrate 111.

FIG. 2 shows a neutralizer according to the present invention.
The basic structure is the same as that of the hollow cathode type neutralizer shown in FIGS.
In the present invention, the anode 201 and the cathode 202 of the neutralizer are made of a material having the same coefficient of thermal expansion.
When the anode 201 and the cathode 202 are made of a material having the same thermal expansion coefficient, the thermal expansion coefficients of the anode 201 and the deposit 208 are also equal. For this reason, even if the anode 201 and the deposit 208 are heated by the plasma, the mutual thermal expansion amounts are equal, and the stress generated at the interface between the anode 201 and the deposit 208 is greatly reduced. For this reason, even if the deposit 208 accumulates on the anode 201, it does not easily drop onto the substrate, and particles can be reduced.
In the present invention, 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 a metal or a material containing a metal.

  When the anode 201 and the cathode 202 are made of the same material, it is possible to further reduce particles. Since the materials of the anode 201 and the deposit 208 are the same, the adsorptivity between the anode 201 and the deposit 208 is improved, so that the risk of dropping onto the substrate can be further reduced. .

  In the case where the anode 201 and the cathode 202 are made of the same material, titanium, molybdenum, tantalum, or the like is used. In particular, titanium is preferable from the viewpoint of ease of processing, low sputtering rate, high discharge efficiency, and the like.

  From the viewpoint of a low sputtering rate, conductive ceramics can be used as the material of the anode 201 and the cathode 202. 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.

  An example of processing an electronic component by ion beam etching using the neutralizer according to the present invention is shown 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 is composed of three electrodes. When viewed from the plasma forming chamber 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 electrode is grounded.
An ion beam is extracted from the grid 109 to the processing chamber 101. The processing chamber 101 is evacuated to about 1.0 × 10 ⁻² Pa by the exhaust pump 103.

At this time, in order to neutralize the ion beam extracted from the grid 109, electrons are supplied from the neutralizer 113 to the ion beam.
Both the cathode 202 and the anode 201 of the neutralizer 113 are made of titanium. First, the discharge gas is introduced into the neutralizer 113 through the gas introduction control unit 205 from the gas introduction path 204 at 5 sccm. Ar is used as the discharge gas.
A voltage is applied to the cathode 202 of the neutralizer so that the potential difference with respect to the anode 201 becomes −200 V, and plasma is formed in the hollow portion 207 of the cathode 202. A voltage of +24 V with respect to the ground potential is applied to the anode, and electrons are extracted from the plasma formed in the hollow portion 207 and emitted toward the processing chamber 101. The ion beam extracted from the grid 109 by the electrons is neutralized.

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

DESCRIPTION OF SYMBOLS 100 Ion beam etching apparatus 101 Processing chamber 102 Plasma formation chamber 103 Exhaust pump 104 Belger 105 Gas introduction part 106 Antenna 107 Matching device 108 Electromagnetic coil 109 Grid 110 Substrate holder 111 Substrate 112 Discharge power supply 113 Neutralizer 118 Faraday shield 201 Anode 202 Cathode 203 Insulator 204 Gas introduction path 205 Gas introduction control unit 206 Power supply 208 Deposit

Claims (6)

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 comprising:
The processing chamber is equipped with a neutralizer that emits electrons,
The neutralizer is
A cathode having a hollow portion in which plasma is formed;
An anode facing the cathode and extracting electrons from the plasma formed in the hollow portion;
Voltage application means for applying a negative voltage to the cathode and a positive voltage to the anode;
A gas introduction part for introducing a discharge gas into the hollow part,
An ion beam processing apparatus, wherein the anode and the cathode are made of a material having the same coefficient of thermal expansion.   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 2, wherein the anode and the cathode are made of titanium. A cathode having a hollow portion in which plasma is formed;
An anode facing the cathode and extracting electrons from the plasma formed in the hollow portion;
Voltage application means for applying a negative voltage to the cathode and a positive voltage to the anode;
A gas introduction part for introducing a discharge gas into the hollow part,
The neutralizer is 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 4, wherein the anode and the cathode are made of the same material.   The neutralizer according to claim 5, wherein the anode and the cathode are made of titanium.