JPH09223594A - Beam source and micro-working method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To extract a large amount of low energy high speed atomic beam and plasma jet, and utilize the same in a vacuum by introducing gas into a discharge vessel around which a high frequency coil is wound so as to produce plasma to extract from a plasma jet nozzle. SOLUTION: Gas 26 is introduced into a discharge vessel 21 made of insulating material and of 10 to 200mm in inner diameter in the vicinity of which a coil 25 is wound via a gas introduction pipe 22. A high frequency current is supplied from a high frequency power supply 24 to the coil 25 via a matching unit so as to produce high density plasma 27 in the discharge vessel 21. The plasma 27 is extracted from a supersonic nozzle or a hypersonic nozzle 23 whose nozzle throat portion hole-diameter is 10 to 20mm and whose nozzle outlet hole hole-diameter is 30 to 50mm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a beam source for generating a low-energy active particle beam and a low-damage microfabrication method using the energy beam source in a high vacuum.

[0002]

2. Description of the Related Art As a conventional technique, a conventional high-speed atomic beam source will be described. Atoms and molecules that are in thermal motion in the atmosphere at room temperature have a kinetic energy of about 0.05 eV. Atoms and molecules that fly with much higher kinetic energy than this are called fast atoms, and when emitted in a directional beam, they are called fast atom beams.

An example of the structure of a fast atom beam source which emits argon atoms having a kinetic energy of 0.5 eV to 10 keV among the fast atom beam sources which have been conventionally announced to generate a fast atom beam of gas atoms is shown in FIG. Shown in. The main structure is composed of a cylindrical cathode 1, a donut-shaped anode 2, a high voltage power source 3, a gas introduction pipe 4, an argon gas plasma 6, a fast atom emission hole 7, a fast atom beam 8 and the like.

After the components other than the power source of the high-speed atomic beam source and the discharge stabilization resistor (not shown) are put in a vacuum container and sufficiently evacuated, argon gas is injected into the cylindrical cathode 1 from the gas introduction pipe 4. To do. Here, a DC high voltage power supply applies a DC voltage so that the anode has a positive potential and the cathode has a negative potential. This causes discharge between the cathode and the anode, plasma is generated, and argon ions and electrons are generated.
Further, in this discharge, the electrons emitted from the bottom surface 1a of the cylindrical cathode are emitted toward the anode 2, pass through the central hole of the anode 2, and reach the bottom surface on the opposite side of the cylindrical cathode,
Here, it loses its speed and reverses, and begins to accelerate toward the anode 2 again. Thus, the electrons oscillate at a high frequency between the two bottom surfaces of the cylindrical cathode through the central hole of the anode 2, and during that time, they collide with the argon gas and generate a large number of argon ions.

The argon ions thus generated are accelerated toward the bottom surface 1a of the cylindrical cathode to obtain sufficient kinetic energy. This kinetic energy is 1 k when the discharge sustaining voltage between the anode and the cathode is, for example, 1 kV.
The value is about eV. The space near the bottom surface 1a of the cylindrical cathode is a turning point of electrons that vibrate at high frequency, and is a space where many low energy electrons are present. Argon ions incident into this space collide with electrons and recombine to return to argon atoms. In the collision between an ion and an electron, the mass of the electron is negligibly smaller than that of the argon ion, so that the kinetic energy of the argon ion is transferred to the atom as it is and becomes a fast atom with almost no loss. Therefore, the kinetic energy of fast atoms in this case is 1 ke
V or so. The argon fast atoms are emitted as fast atoms from the emission hole formed in one end face of the cylindrical cathode.

Next, an example of a conventional plasma jet generator is shown in FIG. This plasma jet generator includes a gas introduction unit 11, a cathode 12, an anode 13, a DC high voltage power supply 14
It is composed of As is clear from the figure, the introduced gas 15 generates plasma 17 by arc discharge occurring between the anode 13 and the cathode 12, and the plasma 17 is emitted as a plasma jet from the nozzle 13a provided in the anode. It Also, in order to suppress excessive heating,
In some cases, the cooling water 16 is caused to flow to perform water cooling on the electrode portion.

[0007]

In the above-described method of producing a high-speed atomic beam or plasma jet, the conventional high-speed atomic beam source, when performing a process of high beam density,
By performing high-voltage discharge of about 1 kV or more, a high-speed atom beam with high discharge current and high energy density was obtained. However, for example, when low-energy discharge is performed, only a low discharge current value can be obtained, and it is necessary to take some measures. This is the same even when a magnetic field from a magnet is used, and is a characteristic of direct current discharge. Therefore, a low discharge current means that the amount of generated ions is low, and that the emitted fast atom dose is low.

Further, in the conventional plasma jet generator, since arc discharge is used, there are
This is a major problem for processes that do not like the effects of contamination by impurities. Due to the arc discharge, the electrode material is excessively heated and the sputtered particles are emitted, whereby a large amount of particles of the electrode material are generated as impurities. In addition, since the plasma jet discharge nozzle is usually used at a low vacuum pressure, the plasma jet discharge nozzle may be a tapered nozzle, a pipe shape, or a cylindrical hole shape. However, in a high vacuum for fine processing, such a nozzle has a problem that the transport efficiency of plasma and active radical particles is significantly reduced.

The present invention has been made in view of the above-mentioned circumstances, and a beam source that can be used in a high vacuum and can extract a large amount of low-energy high-speed atom beams and plasma jets and the beam source thereof. An object of the present invention is to provide a microfabrication method using

[0010]

A beam source according to the present invention comprises a discharge vessel, a plasma generating mechanism, a gas introducing mechanism, and a plasma jet nozzle for emitting plasma generated by the plasma generating mechanism as a jet beam. It is characterized by having.

Further, the plasma jet nozzle is a supersonic nozzle or a hypersonic nozzle.

Further, the plasma jet nozzle is made of a conductive material, and an electrode is provided upstream of the plasma generating portion, and a DC voltage, a pulse voltage, or a DC voltage is applied between the electrode and a downstream electrode including the plasma jet nozzle. It is characterized in that a high frequency voltage is applied and the energy beam and the plasma jet that are electrically accelerated are emitted simultaneously or alternately.

Further, the downstream electrode including the electrode and the plasma jet nozzle is formed in a flat plate structure facing each other.

Further, the plasma generation mechanism uses an inductively coupled high frequency discharge mechanism.

Further, the beam source according to any one of claims 1 to 5 is used to perform fine processing in a high vacuum.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a plasma generating mechanism, a discharge vessel, a gas introducing mechanism, a plasma jet discharge nozzle, a beam source composed of electrodes, and a beam emitted from the beam source are The present invention relates to a microfabrication method for performing microfabrication by reaching a sample installed in a high vacuum container. Unlike ordinary plasma jet generation, in order to obtain low energy and high density plasma instead of arc discharge plasma, inductively coupled high frequency discharge, EC
A plasma generation mechanism such as R discharge, helicon wave discharge, and high voltage DC discharge is used. Then, by using a supersonic nozzle for discharging a plasma jet or a hypersonic nozzle, the generated plasma and radical particles are pressured to 10 ^−3.
It is possible to efficiently reach the sample surface in a high vacuum below Torr.

Further, an electrode is arranged upstream of the high-density plasma generated by the high-frequency electric field, and an electrode having a supersonic nozzle for plasma jet discharge is arranged downstream of the high-density plasma.
By applying a DC voltage between the downstream electrodes, the plasma jet from the plasma jet discharge nozzle,
A fast atom beam having energy corresponding to the applied voltage can be emitted. Therefore, the surface of the sample in the high vacuum can be irradiated with both the plasma jet and the high-speed atomic beam to perform the fine processing process.

A pipe for introducing gas and a supersonic nozzle or a hypersonic nozzle for emitting a plasma jet and a high-speed atomic beam are attached to the discharge vessel. The generated plasma is efficiently transported onto the sample surface in a high vacuum by a supersonic nozzle such as a Laval nozzle or a conical nozzle or a hypersonic nozzle. At this time, in a high vacuum,
The use of a tapered nozzle or a pipe-shaped nozzle such as a nozzle for a plasma jet in an incompressible fluid or a low vacuum results in very inefficient plasma transportation. This is because the pressure difference at the nozzle outlet is so large that the plasma jet from the pipe nozzle or the tapered nozzle outlet spreads over a very wide area, and only a small part of the plasma jet can reach the sample. .

As described above, in the high vacuum, the same as the efficiency of fluid transportation, the supersonic nozzle and the hypersonic nozzle are used to remove the ions and radical particles in the plasma.
As it can be accelerated and the velocity vectors can be made uniform, and the pressure difference at the nozzle outlet can be reduced, plasma and radical particles can be diffused in a wide area downstream of the nozzle, such as a tapered nozzle or a pipe nozzle. The plasma and radical particles can be efficiently transported to the sample surface.

In addition to the above-mentioned structure, a plate-like electrode is arranged upstream of the plasma generating part, electrodes having supersonic nozzles are arranged in parallel with each other, and the electrodes are arranged between the electrodes. Apply DC voltage. Then, not only the plasma jet can be efficiently discharged, but also the fast atom beam having the energy according to the applied voltage can be simultaneously discharged from the nozzle. When this DC voltage is applied in a pulsed form, a fast atom beam is emitted during the pulsed DC voltage application time.

In the fast atom beam in this case, the ions in the plasma are accelerated in the direction of the downstream electrode in accordance with the electric field based on the applied voltage, and charge exchange is performed with the residual gas particles in the nozzle to become fast neutral particles. , As a high-speed atomic beam, is emitted from the nozzle outlet. That is, since the plasma generation mechanism independently functions, the direct-current voltage that determines the fast atom beam energy can supply the fast atom beam with low energy even at a low voltage. Therefore, a low energy to high energy fast atom beam can be generated by selecting the DC voltage. When microfabrication is performed by simultaneously applying a low-energy fast atom beam and a highly reactive plasma jet to the sample surface, low energy and low damage, which was difficult with conventional microfabrication using only a DC discharge type fast atom beam. It enables fine processing. In addition, high-speed processing utilizing high reactivity by plasma jet is also possible.

[0022]

1 shows a beam source according to a first embodiment of the present invention. Discharge vessel 21 made of an insulating material such as ceramics
A gas introduction pipe 22 and a plasma jet supersonic nozzle 23 are arranged in the space. For example, the inner diameter of the cylindrical container is about 10 mm to 200 mm. Discharge vessel 21
In order to generate a glow discharge inside, an inductively coupled high frequency power source 24
When a coil 25 is wound in the vicinity of the container by using, and a high frequency (RF) current is applied to the coil through a matching device,
A high density plasma 27 can be generated in the discharge vessel 21. For example, chlorine gas 26 is introduced into the gas introduction pipe 22, and the discharge tube 21 having an inner diameter of 60 mm and a length of 100 mm is introduced.
In addition, a nozzle 22 having a nozzle throat hole diameter of 10 to 20 mm and a nozzle outlet hole diameter of 30 to 50 mm is used. A coil 25 in which a water-coolable copper tube is wound for 1 to 3 turns is used for glow discharge. By passing a high frequency current through the coil, a high density plasma 27 of chlorine gas particles is generated. The generated chlorine plasma 27 is generated by the supersonic nozzle 23.
As a result, a sample placed in a vacuum container in a high vacuum state of about 10 ⁻³ Torr or less is irradiated as a plasma jet 28 for fine processing.

FIG. 2 shows a beam source according to the second embodiment of the present invention. A plate-shaped electrode 29 having a gas passage hole and a supersonic nozzle 23 are arranged in a discharge tube made of an insulating material such as ceramics.
The nozzle 23 is a part of the downstream electrode 30 made of a conductive electrode material. The high-density plasma 27 is formed between the upstream electrode 29 and the downstream electrode 30 including the supersonic nozzle.
The coil 25 having 1 to 3 turns is installed in the discharge tube 21 so as to generate. 13.56M on the coil 25
High frequency plasma 27 by applying RF high frequency voltage of Hz
Is generated. As the gas 26, an inert gas such as argon, or a reactive gas such as chlorine or fluorine-containing gas when processing using a chemical reaction is used.

At this time, as shown in FIG.
9 is applied to the downstream electrode 30 including the nozzle, not only the plasma jet 28 is emitted from the nozzle, but also the fast atom beam 31 having energy corresponding to the applied voltage is emitted from the nozzle hole 23. It Therefore, a high-density plasma can be obtained even with low energy, so that a large amount of low-energy fast atom beams can be emitted and a highly reactive plasma jet can be emitted. It is possible to perform efficient processing by irradiating with a plasma jet. By applying a pulsed voltage between the upstream electrode and the downstream electrode, the high-speed atom beam can be intermittently ejected.

As samples, Si, SiO ₂ , GaAs
It is possible to process semiconductor materials such as glass, ceramics, and metals. Compared with conventional processing using only high-speed atomic beams, plasma jet processing can be used in combination, which is extremely efficient. In addition, since low energy and highly anisotropic processing are possible, it is effective for etching a high aspect ratio of an insulating thin film such as an LSI.

[0026]

As described above, the following excellent effects can be expected by using the present invention. That is, it is difficult to obtain high-density plasma when discharging with low energy in the microfabrication by the conventional DC discharge type high-speed atomic beam source,
It was difficult to generate a high-density, low-energy fast atomic beam. Also, when arc discharge or tapered nozzle used in plasma jet in low vacuum is used, heating of electrode material or contamination by spatter poses a problem, or when processing in high vacuum, plasma jet transport The efficiency is extremely poor.

The present invention solves such a problem and provides a beam source capable of efficiently performing fine processing of semiconductor materials and insulators in a high vacuum. A high density glow discharge is used to reduce it. In addition, a supersonic nozzle or a hypersonic nozzle is used in order to increase the transportation efficiency of the plasma jet. Furthermore, by using an electrode inside the discharge tube, where the electrode is placed upstream of the plasma and the supersonic nozzle is placed downstream of the plasma, a DC voltage is applied between both electrodes, so that low to high energy can be achieved. It is possible to emit a large amount of fast atom beams capable of controlling energy. In this case, since both the plasma jet and the high-velocity atomic beam can be emitted, it is possible to realize processing with high reactivity and excellent anisotropy and low damage. For example, semiconductor device or LS
The scientific and industrial significance of the present invention is very large and significant, such as being effective in the processing of I, the quantum effect element, the laser element using the quantum effect, and the production of the light emitting element / optical lens element.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a beam source according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of a beam source according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a conventional high speed atomic beam source.

FIG. 4 is an explanatory diagram of a conventional plasma jet generator.

[Explanation of symbols]

 21 Discharge Vessel (Discharge Tube) 22 Gas Inlet 23 Supersonic Nozzle 24 High Frequency Power Supply 25 Coil 26 Gas 27 Plasma 28 Plasma Jet Nozzle 29 Plate (Upstream) Electrode 30 Downstream Electrode 31 High Speed Atomic Beam 32 DC Power Supply

Claims (6)

[Claims] 1. A beam source, comprising: a discharge container, a plasma generating mechanism, a gas introducing mechanism, and a plasma jet nozzle that discharges the plasma generated by the plasma generating mechanism as a jet beam. 2. The beam source according to claim 1, wherein the plasma jet nozzle is a supersonic nozzle or a hypersonic nozzle. 3. The plasma jet nozzle is made of a conductive material, and an electrode is provided in an upstream portion of a plasma generation portion, and a DC voltage, a pulse voltage, or a DC voltage is provided between the electrode and a downstream electrode including the plasma jet nozzle. 3. The beam source according to claim 1, wherein a high frequency voltage is applied and the energy beam and the plasma jet electrically accelerated are emitted simultaneously or alternately. 4. The beam source according to claim 3, wherein the downstream electrode including the electrode and the plasma jet nozzle is formed in a flat plate structure facing each other. 5. The beam source according to claim 1, wherein the plasma generation mechanism uses an inductively coupled high frequency discharge mechanism. 6. A fine processing method using the beam source according to claim 1 to perform fine processing in a high vacuum.