JP4114770B2 - Vacuum processing equipment for oxygen ion generation - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a vacuum processing apparatus for generating oxygen ions.
[0002]
[Prior art]
FIG. 1 is a schematic plan view of a conventional oxygen ion generator. Referring to FIG. 1, an oxygen ion generator 1 includes a metal ion source chamber 2, a charge conversion cell chamber 4 having a charge conversion cell 3, and an ion irradiation chamber 5. Further, the ion source chamber 2, the charge conversion cell chamber 4 and the ion irradiation chamber 5 are provided with an opening 7 of the ion source chamber 2 formed of a circular hole having a diameter of about 4 to 8 mm through an insulating cylinder 6 made of alumina or epoxy resin. And the ion source chamber side opening 8 and the irradiation chamber side opening 8 ′ of the charge conversion cell 3 communicate with each other.
[0003]
Inside the ion source chamber 2, a filament 10 made of a refractory metal such as tungsten, tantalum, or rhenium can be operated by an external filament power source 9, and the ion source chamber 2 itself has an arc power source 11 or The container potential is set by conducting to the extraction electrode power source 12. Further, the gas inlet 13 of the ion source chamber 2 is connected to a gas flow rate regulator 16 and a decompressor 17 communicating with the oxygen cylinder 15 via an inlet valve 14. These gas introduction parts are made of metal in order to prevent ignition due to static electricity.
[0004]
On the other hand, in the vicinity of the ion source chamber side opening 8 of the charge conversion cell 3 inside the charge conversion cell chamber 4, an extraction electrode 19 that is insulated from the cell 3 by the insulating sleeve 18 and is formed in a tapered shape is provided. At this time, the minus side of the lead electrode power supply 12 is grounded, and the lead electrode 19 is set to the ground potential. A tip hole 20b of the nozzle portion 20a of the vaporizer 20 is provided in a substantially central portion of the charge conversion cell 3 so as to protrude into the cell 3 from below. Then, coil heaters 21a and 21b are wound around the charge conversion cell 3 and the vaporizer 20 from the outside in order to keep warm.
[0005]
In the irradiation chamber 5, an irradiated body 23 made of an oxide held on the substrate stage 22 is provided so that the current flowing from the substrate stage 22 can be measured by an ammeter 24.
[0006]
When oxygen ions are generated by the conventional apparatus configured as described above, the entire apparatus 1 is previously evacuated by a vacuum exhaust pump (not shown) through the exhaust port 25 of the ion source chamber 2 and the exhaust port 26 of the irradiation chamber 5. A low pressure state of 1.3 × 10 ⁻³ Pa or less is set, and then the filament power supply 9 is operated to start thermionic emission from the surface of the incandescent filament 10. In this state, a voltage of 40 to 130 V is applied by the arc power supply 11 and the gas flow rate regulator 16 and the decompressor 17 are operated to introduce the introduction valve so that the oxygen gas has a flow rate of 2 to 10 sccm and is about 1 atm. 14 is opened, and oxygen gas is introduced into the ion source chamber 2. At this time, oxygen plasma is generated by the thermoelectrons from the incandescent filament 10 and the introduced oxygen gas. In this state, a voltage of 15 to 20 kV is applied by the extraction electrode power source 12 to emit positively charged oxygen ions from the opening 7 of the ion source chamber 2, and the flight trajectory is maintained through the opening 8. To enter the charge conversion cell 3.
[0007]
On the other hand, in the charge conversion cell 3, 3 to 5 grams of metal sodium is filled in the vaporizer 20 disposed in the lower portion thereof, and the cell 3 and the vaporizer 20 are heated and kept at about 200 to 400 ° C. An air flow from the cell 3 to the irradiation chamber 5 is generated by sodium vapor.
[0008]
At this time, as described above, the positively charged oxygen ions incident on the charge conversion cell 3 collide with sodium atoms or sodium molecules in the sodium vapor, and in the process, the electrons of the sodium atoms are deprived. Ions are converted into negative charges (see FIG. 2).
[0009]
The oxygen ions obtained in this way are useful for oxidation processes for semiconductor manufacturing and oxidation processes for transparent conductive films for display devices, and can also be used in sterilization applications utilizing the oxidizing power in the chemical field. .
[0010]
[Problems to be solved by the invention]
By the way, in the above conventional oxygen ion generator, positively charged oxygen ions are first generated and then converted into negatively charged ions to obtain desired oxygen ions. For this reason, the apparatus becomes complicated corresponding to the multi-step process, and it becomes difficult to change the oxygen ion generation conditions.
[0011]
For example, in order to increase the amount of ions, immediate effect can be expected by widening the opening 7 of the ion source chamber 2, but in order to perform plasma ignition of the filament 10 in the ion source chamber 2 at this time, 1. It is necessary to maintain a pressure condition of about 3 × 10 Pa. For this purpose, it is required to introduce a large amount of oxygen gas into the ion source chamber 2 with high accuracy. Further, in order to sufficiently emit positively charged oxygen ions generated in the ion source chamber 2 and reach the conversion cell 3, it is necessary to stably maintain the potential difference between the opening 7 serving as the anode and the extraction electrode 19. For this purpose, the pressure condition between the two electrodes is preferably 1.3 × 10 ⁻³ Pa or less. Therefore, a powerful vacuum exhaust pump is required for the ion source chamber 2.
[0012]
Such inconveniences in handling are the same in the irradiation chamber 5. For example, when the irradiation chamber side opening 8 ′ of the charge conversion cell 3 is widened to increase the amount of ions, this increases. Therefore, in order to emit oxygen ions as an ion beam against sodium vapor flowing out, it is necessary to set the inside of the conversion cell 3 to 1.3 × 10 ⁻³ Pa or less so as to ensure an average free process of oxygen ions. There is. For this reason, as in the case of the ion source chamber 2, the irradiation chamber 5 is also equipped with a powerful vacuum pump.
[0013]
Further, for example, if the voltage applied to the extraction electrode 19 for generating oxygen ions (about 20 kV in the apparatus of FIG. 1) is reduced for the purpose of power saving, the amount of positively charged oxygen ions generated in the ion source chamber 2 is reduced. Therefore, the charge conversion efficiency is reduced when negatively charged oxygen ions are generated using this as a conversion species.
[0014]
In addition, the conversion loss in the process in which oxygen ions are converted from positive to negative charges in the conversion cell 3 cannot be ignored.
[0015]
In view of the above problems, the present invention can obtain a desired amount of negatively charged oxygen ions with a simple structure. For example, the irradiation area of an ion beam for increasing the amount of ions and the voltage applied to the extraction electrode can be reduced. It is an object of the present invention to provide an oxygen ion generator that can be easily changed in conditions such as increase and is useful in handling.
[0016]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention comprises a porous ceramic substrate, a heating means comprising a lamp and a reflecting plate for reflecting the heat of the lamp, and an oxygen introduction means, and the oxygen introduction means The oxygen is supplied to the space surrounded by the reflector through a gas introduction pipe inserted into the reflector, and the heating means is operated in an oxygen atmosphere by operating the oxygen inlet. The porous ceramic substrate was heated to 600 to 900 ° C. to generate oxygen ions in the process of oxygen permeating through the porous ceramic substrate.
[0017]
With such an apparatus, oxygen species can be desorbed from the porous ceramic substrate as negatively charged oxygen ions, and the amount of negatively charged oxygen ions generated in this way is reduced by the heating means. Handling has been improved in that the conditions can be easily changed, such as an increase / decrease by adjustment.
[0018]
In this case, the above-described vacuum processing apparatus for oxygen ion generation is performed with the porous ceramic substrate facing the porous ceramic substrate through the electrically insulating material, the porous ceramic substrate as the negative electrode, and the porous conductive plate as the ground potential. When configured to irradiate ions to the substrate stage side that holds the irradiated body, the irradiation direction of negatively charged oxygen ions generated from the porous ceramic substrate is focused toward the porous conductive plate, so it passes through the conductive plate. After that, the resulting ion beam has a high density. Therefore, it becomes easy to ensure a desired amount of oxygen ions.
[0019]
Furthermore, in this case, when the porous conductive plate is grounded and a voltage is applied with the porous ceramic substrate as the negative electrode, the generated oxygen ions can be reliably charged to a negative charge.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 3 is a schematic plan view of the vacuum processing apparatus for generating oxygen ions according to the present invention. Parts having functions equivalent to those in FIG. 1 are denoted by the same reference numerals. Referring to FIG. 3, an ion source chamber 2 and a substrate stage 22 holding an irradiated body 23 are arranged in an irradiation chamber 5 provided with an exhaust port 26, and an ammeter outside the apparatus is disposed on the substrate stage 22. 24 is connected.
[0021]
In the ion source chamber 2, a lamp 27 operated by a filament power source 9, a reflecting plate 28 for reflecting heat generated thereby, and a disk-shaped porous ceramic substrate 29 having a diameter of about 5 cm are disposed. The ceramic substrate 29 is fixed by a holder 30 provided on the wall surface of the ion source chamber 2. Further, an extraction electrode 19 made of a porous metal plate is attached to the porous ceramic substrate 29 on the substrate stage 22 side through the electrical insulating material 6 at an interval of about 3 mm from the substrate 29. At this time, the metal constituting the extraction electrode 19 is made of an antioxidant such as molybdenum. Further, a gas introduction pipe 31 is provided in a space surrounded by the reflection plate 28.
[0022]
The irradiation chamber 5 and the ion source chamber 2 are made of metal in order to ensure conductivity, but both are electrically insulated by an insulator 32, and the extraction electrode 19, the irradiation chamber 5 and the ground cover 33 having a ground potential are electrically insulated. And keep the potential difference.
[0023]
In order to generate oxygen ions using the apparatus of FIG. 3, the inside of the irradiation chamber 5 is previously maintained at 1.3 × 10 ⁻³ Pa or less by an unillustrated vacuum exhaust pump connected to the exhaust port 26, and in this state, The lamp 27 is turned on by the filament power supply 9. At this time, light emitted from the lamp 27 is reflected by the reflecting plate 28 and the porous ceramic substrate 29 is heated. The substrate temperature at that time is preferably in the range of 600 to 900 ° C. by adjusting the filament power supply 9.
[0024]
Then, by opening the inlet valve 14, while introducing oxygen gas at a flow rate 0.01~0.1sccm at through the gas inlet pipe 31, the reflecting plate 28 surrounded by a space 1.3 × 10 ^- Keep at about ³ Pa.
[0025]
In this way, a voltage of −300 V is applied to the ion source chamber 2 by the extraction electrode power source 12. At this time, the porous ceramic substrate 29 becomes a negative electrode, and as a result, oxygen species in the space surrounded by the reflector 28 are charged with a negative charge in the process of passing through the porous ceramic substrate 29, and thus inside the irradiation chamber 5. A current is generated by landing on the irradiated object 23.
[0026]
The current value measured by the ammeter 24 of the apparatus of FIG. 3 is about 2 mA (about 100 μA / cm ² ), which is much better than the current value of ^{2 to} 15 μA obtained by the measurement of the ammeter 24 of FIG. can get.
[0027]
【The invention's effect】
As is clear from the above description, in the oxygen ion generating vacuum processing apparatus of the present invention, the oxygen species that are the source of oxygen ions are directly charged with negative charges without undergoing charge conversion from positive to negative, and oxygen ions Is generated. Since the oxygen ion generation process is simplified in this way, the charge conversion loss during oxygen ion generation can be suppressed, the amount of ions can be secured efficiently, and the device structure is also simplified for handling. Improves usability. For this reason, it can be expected that the conditions for oxygen ion generation can be easily changed.
[Brief description of the drawings]
1 is a conventional oxygen ion generator. FIG. 2 is a process for generating negatively charged oxygen ions in the oxygen ion generator of FIG. 1. FIG. 3 is a vacuum processing apparatus for generating oxygen ions according to the present invention. [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum processing apparatus for oxygen ion generation 6 Electrical insulation material, insulation cylinder 12 Power supply 19 for extraction electrodes Porous conductive plate 27 Lamp (heating means)
28 Reflector (heating means)
29 Porous ceramic substrate 31 Gas introduction pipe

Claims (2)

A heating means comprising a porous ceramic substrate, a lamp and a reflecting plate for reflecting the heat of the lamp, and an oxygen introducing means ; oxygen from the oxygen introducing means is inserted into the reflecting plate The porous ceramic substrate is heated to 600 to 900 ° C. by the heating means in an oxygen atmosphere that is supplied to the space surrounded by the reflecting plate through the gas introduction pipe and operates the oxygen introduction means. A vacuum processing apparatus for generating oxygen ions, wherein oxygen ions are generated in the process of oxygen permeating through the porous ceramic substrate. A porous conductive plate is opposed to the porous ceramic substrate through an electrically insulating material, the porous ceramic substrate is set as a negative electrode, the porous conductive plate is set as a ground potential, and the substrate stage side holding the irradiated object is irradiated with ions. The vacuum processing apparatus for generating oxygen ions according to claim 1.

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