JP2669660B2 - Flash fast atomic beam source - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to an LSI composed of a semiconductor, a metal, and an insulator.
A high-speed, high-convergence, high-power atomic beam that is suitable as a beam used in the case of producing an electronic element pattern by sputter etching on a material for use or performing composition analysis of an insulator in a pulsed manner. It is related to a flash fast atom beam source.

[Prior art] Atoms in thermal motion at room temperature are approximately 0.05 eV
(Electron volts) have kinetic energy before and after. Atoms and molecules that fly with much higher kinetic energy than this are collectively called "fast atoms", and when they flow in one direction in a beam, they are called "fast atom beams".

For LSI materials consisting of semiconductors, metals and insulators,
Until now, ion beam was used when manufacturing electronic element patterns by sputter etching or when analyzing the composition of insulators. Had become. However, if a fast atom beam having no charge is used instead of the ion beam, troubles due to charging can be avoided, and improvement in processing accuracy and analysis reliability can be expected. Therefore, conventionally, a high-speed atomic beam source with high convergence and high output has been demanded as a beam suitable for such an application.

FIG. 4 shows an example of a fast atom beam source that emits argon atoms having a kinetic energy of 0.5 to 10 keV among the fast atom beam sources that generate a fast atom beam of gaseous atoms that have been conventionally announced. In the figure, 1 is a cylindrical cathode, 2 is a donut-shaped anode, 3 is a high voltage DC power supply of 0.5 to 10 keV, 4 is a gas nozzle,
5 is an argon gas, 6 is a plasma, 7 is a fast atom beam emission hole, 8 is a fast atom beam, and 9 is a discharge stable resistance.

The operation of this conventional example is as follows. After components other than the DC high-voltage power supply 3 and the discharge stabilizing resistor 9 are put in a vacuum vessel and sufficiently evacuated, an argon gas 5 is injected into the inside of the cylindrical cathode 1 from a gas nozzle 4. Here, the DC high voltage power supply 3 causes the anode 2 to have a positive potential and the cathode 1 to have a negative potential,
Apply high DC voltage. As a result, a glow discharge occurs between the cathode 1 and the anode 2, and plasma 6 is generated, and argon ions and electrons are generated. Further, in this discharge, electrons emitted from the bottom surface 1a of the cylindrical cathode 1 are accelerated toward the anode 2, pass through the central hole of the anode 2, and reach the bottom surface 1b opposite to the cylindrical cathode 1, and Here, the vehicle loses its speed and reverses, and starts accelerating toward the anode 2 again. In this way, the electrons vibrate between the bottom surfaces 1a and 1b of the cylindrical cathode 1 through the central hole of the anode 2 at high frequency, and collide with the argon gas during that time to generate a large number of argon ions. The argon ions thus generated are accelerated toward the bottom surface of the cylindrical cathode 1 to obtain sufficient kinetic energy. This kinetic energy has a value of about 1 keV when the discharge sustaining voltage between the anode 2 and the cathode 1 is, for example, 1 kV. In the space near the bottom surface of the cylindrical cathode 1, the argon ions come into contact with the remaining argon gas and lose the charge, returning to neutral argon atoms. The space in the vicinity of the bottom surface of the cylindrical cathode 1 is a turning point of electrons that oscillate at a high frequency, and is a space where many low-energy electrons are present. Argon ions incident on this space are recombined with the electrons. Return to argon atom. The contact between the argon ion and the argon gas is not so severe that the kinetic energy of the argon ion changes drastically, so the kinetic energy of the argon ion is passed on to the neutral argon atom as it is, resulting in a high-speed atomic beam. Is born. Also, in the collision between argon ions and electrons, the mass of the electrons is so small as to be negligible compared to the argon ions, so that the kinetic energy of the argon ions is inherited by the argon atoms with little loss, and the argon atoms become It becomes a fast atom. Therefore, the kinetic energy of the fast atom in this case is 1k
It is about eV. The fast atoms generated in this manner are emitted from the emission hole 7 formed in one bottom surface 1b of the cylindrical cathode 1.
Is emitted as a fast atom beam 8.

[Problems to be Solved by the Invention] However, in the high-speed atomic beam source according to the above-mentioned conventional technique, the plasma 6 spreads to the inside of the cylindrical cathode 1, so that argon ions from the anode 2 toward the emission hole 7 are generated. It was difficult to converge, so the convergence of the fast atomic beam 8 was poor, and the discharge current was about 1 A at the maximum, which was not suitable for emitting a high-power beam.

The present invention was devised to solve the above problems, and is a flash high-speed device capable of generating a high-speed atomic beam source with high convergence and high output suitable for use in processing and analysis of minute regions. The purpose is to provide an atomic beam source.

[Means for Solving the Problems] One configuration of the flash high-speed atomic beam source of the present invention for achieving the above-mentioned object is to provide an opening through which an anode and a high-speed atomic beam arranged facing the anode pass in vacuum. Part, a gas nozzle for injecting gas into the inside of the cylindrical cathode, a capacitor charged from a DC high-voltage power supply, and connected in series with the capacitor between the anode and the cathode. And a switch means for generating an electric discharge in the gas, and the high-speed atomic beam is obtained by the electric discharge.

In addition, as another configuration, in a vacuum, a cylindrical cathode having an anode and an opening arranged to face the anode through which a high-speed atom beam passes, and a cylindrical cathode having a valve that opens and closes at high speed are provided. A gas nozzle for injecting gas in a pulsed manner and a capacitor connected between the anode and the cathode for charging from a DC high voltage power source and causing discharge of the gas are provided, and the high-speed atomic beam is obtained by the discharge. It is characterized by

[Operation] According to the present invention, the gas injected into the cathode is discharged by the switch means or the above-mentioned gas injected in a pulsed manner at a high DC voltage charged in the capacitor, and an extremely large discharge current is generated by the operation of the capacitor. A large amount of ions are generated by flowing. The ions are accelerated toward the cathode and lose contact with the gas to become a neutral high-speed atomic beam. However, the large amount of the ions generated increases the output of the high-speed atomic beam. Further, since the discharge current is extremely large, the ions are narrowed down by the pinch effect. As a result, the ions heading for the cathode are strongly converged, so that the fast atom beam also has high convergence.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a perspective structural view showing a first embodiment of the present invention. In the figure, 11 is a needle-like anode, 12 is a cathode having an opening through which fast atoms pass through a cylindrical end face and arranged so that the opening faces the anode 11, and 13 is a high withstand voltage capacitor of, for example, about 1 μF. , 14 is, for example, a DC high-voltage power supply having an output of about 30 kV for charging the capacitor 13, 15 is a high resistance for limiting the charging current, 16 is a gas nozzle for injecting gas into the cylindrical cathode 12. , 17 are switches connected in series with the capacitor 13 and connected between the anode 11 and the cathode 12,
Reference numeral 18 denotes a vacuum container which accommodates the anode 11, the cathode 12, the gas nozzle 16, and the like and is evacuated by a vacuum pump or the like (not shown). Reference numeral 19 denotes a high-speed atomic beam generated by a discharge generated in the gas by operating the switch 17.

The operation of the first embodiment configured as described above will be described.
First, the vacuum vessel 18 is sufficiently evacuated, and from the gas nozzle 16,
For example, oxygen gas is injected into the inside of the cylindrical cathode 12. The capacitor 13 has a capacitance of, for example, 1 μF and a high resistance 15 μF.
Is charged to a high voltage of, for example, 30 kV by the DC high-voltage power supply 14. The oxygen gas injected into the cylindrical cathode 12 diffuses and fills the space between the anode 11 and the cathode 12. When switch 17 is turned on in this state, anode 11 and cathode
Discharge occurs during 12 and plasma is generated. Switch 1
7, the inductance including the cathode 12, the anode 11 and the wiring connecting them is several to several tens of μH.
The amount of electricity charged to 13 (30 kV x 1 µF = 0.03 C) is completely discharged in a few µsec. Therefore, the plasma connection time is also about this, and the maximum discharge current when a discharge occurs is several tens to several
At 100 kA, the energy injected into the plasma can reach hundreds of MW, albeit momentarily. Therefore, the density of the plasma is extremely high, the temperature is also high, and a large amount of oxygen ions are generated. Since the discharge current is extremely large, the current is very narrowed by the pinch effect, so that the generated ion beam is also strongly focused. Oxygen ions are accelerated toward the cathode 12, enter the inside of the cylinder of the cathode 12, connect to oxygen gas, lose charge, and return to neutral oxygen atoms. Since oxygen gas is injected from the gas nozzle 16 into the cylindrical cathode 12, the inside of the cylinder has a higher gas pressure than the others, and the efficiency of contact between oxygen ions and oxygen gas is high. Since the contact between oxygen ions and oxygen gas is not so severe that the kinetic energy of the oxygen ions changes drastically, the kinetic energy of the oxygen ions is passed on to the neutral oxygen atoms as they are, and the oxygen ions have high convergence. An atomic beam 19 is created and emitted out of the opening of the cylindrical cathode 12. When the amount of electricity charged in the capacitor 13 is completely discharged, the plasma disappears and the emission of the fast atom beam also stops. Here, the capacitor 13 is charged again, and when the switch 17 is turned on next time, plasma is again generated and the fast atom beam 19 is emitted again. In this way, since the convergence is high and a large amount of oxygen ions are generated, a high-power fast atom beam can be repeatedly obtained in a pulsed manner. When the gas injected from the gas nozzle 16 is, for example, argon, an argon fast atom beam will be generated.

FIG. 2 is a perspective structural view showing a second embodiment of the present invention. In the present embodiment, a valve 21 that opens and closes at a high speed is provided on the gas supply side of the gas nozzle 16 in the first embodiment, and a control mechanism (not shown) replaces the switch 17 and turns on / off in synchronization with opening and closing of the valve 21. A switch 22 for turning off is provided. Other configurations are the same as those of the first embodiment shown in FIG. 1, and the elements indicated by 11 to 16, 18, and 19 in FIG. 2 are the same as the corresponding elements of the same numbers in FIG. Has operation and function.

The operation of the second embodiment having the above configuration is as follows. First, the valve 21 is opened for a short time and then immediately closed. This injects gas into the cylindrical cathode 12 and diffuses it into the anode 11
・ Fill between the cathodes 12. The switch 22 is closed (on) in synchronization with the valve 21 being “open”, and the switch 22 is opened (off) in synchronization with the valve 21 being “closed”. This causes a discharge, and by the same process as in the first embodiment, a fast atom beam with high convergence and high output is emitted in a pulsed manner. According to this second embodiment, the injected gas is
As soon as 13 is completely discharged and the emission of the fast atomic beam 19 stops, it is evacuated by a vacuum pump (not shown).
There is a merit that the inside of the vacuum vessel 18 can always be kept at a high vacuum. In other words, there is an advantage in that the environment such as an object using the high-speed atomic beam can be favorably maintained in use.

FIG. 3 is a perspective structural view showing a third embodiment of the present invention. In this embodiment, the switch 22 is removed from the second embodiment, and the capacitor 13 is connected between the cathode 11 and the anode 12. Other constructions are the same as those of the second embodiment shown in FIG. 2, and elements indicated by 11 to 16, 18, 19, and 21 in FIG. 3 are the same as corresponding elements of the same numbers in FIG. Has the operation and function of.

In this embodiment, when the valve 21 is opened and closed, gas is injected and diffused into the inside of the cylindrical cathode 12 in a pulsed manner, and when the gas pressure between the anode 11 and the cathode 12 rises, a discharge occurs due to dielectric breakdown of the gas. Then, the electric charge stored in the capacitor 13 is discharged at once, and a high-speed atomic beam with high convergence and high output is radiated in a pulse in the same process as in the second embodiment. In this embodiment, as in the second embodiment, the injected gas is immediately discharged by the vacuum pump (not shown) as soon as the emission of the fast atomic beam 19 is stopped by the termination of the discharge of the capacitor 13. The inside of the can always be kept in a high vacuum. Further, the present embodiment has an advantage that the device is simplified because the switch and its control mechanism are unnecessary.

It should be noted that the shapes of the components such as the anode and the cathode and the openings thereof in the above embodiments are merely examples, and the present invention is not limited to the above embodiments. As described above, the present invention can be variously applied according to the gist and can take various embodiments.

[Advantages of the Invention] Similar to the high-speed ion beam, the high-speed atomic beam can be used for processing and analysis such as thin film formation by sputter deposition, fine pattern processing by sputter etching, and material evaluation by secondary ion mass spectrometry. . In particular, since the fast atom beam is non-chargeable, it is effective not only for metals and semiconductors, but also for insulators such as plastics and ceramics, which are not good at the ion beam method.

According to the flash high-speed atomic beam source of the present invention, it is possible to generate a high-output high-speed atomic beam with high convergence, which was difficult to achieve with the conventional high-speed atomic beam sources, and in the above meaning, It has a very beneficial effect on the processing and analysis of those minute regions.

[Brief description of the drawings]

FIG. 1 is a perspective view of the first embodiment of the present invention,
FIG. 2 is a perspective configuration diagram showing a second embodiment of the present invention,
FIG. 3 is a perspective view showing a third embodiment of the present invention,
FIG. 4 is a perspective view showing a conventional example. 11 …… Anode, 12 …… Cathode, 13 …… Capacitor, 14 …… DC high voltage power supply, 16 …… Gas nozzle, 17 …… Switch, 18
…… Vacuum vessel, 19 …… High-speed atomic beam, 21 …… Valve, 22…
…switch.

Claims (3)

(57) [Claims] 1. A cylindrical cathode having an anode and an opening portion through which a high-speed atom beam passes through in a vacuum, a gas nozzle for injecting a gas into the inside of the cylindrical cathode, A capacitor that is charged from a voltage power supply; and a switch connected between the anode and the cathode in series with the capacitor to generate a discharge in the gas by turning on the capacitor. A flash high-speed atomic beam source characterized by the above. 2. The flash high-speed atomic beam source according to claim 1, wherein a valve provided in the gas nozzle to open and close at high speed to inject gas in a pulsed manner, and a mechanism to turn on / off the switch means in synchronization with the opening / closing. And a flash high-speed atomic beam source. 3. In a vacuum, an anode and a cylindrical cathode having an opening through which a high-speed atom beam passes, which is arranged so as to face the anode, and a valve that opens and closes at high speed, have a gas inside the cylindrical cathode. A gas nozzle for injecting the gas in a pulsed manner, and a capacitor that is connected between the anode and the cathode and that is charged from a DC high-voltage power source and causes discharge of the gas, and obtains the high-speed atomic beam by the discharge. Flash fast atomic beam source.