JP2569739B2 - Oxygen atom generation method and apparatus - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for generating oxygen atoms capable of synthesizing oxides such as metals and completely decomposing organic substances at a high speed.

[Conventional technology]

As a means for generating oxygen atoms, there is a method and apparatus for decomposing oxygen molecules by ultraviolet irradiation and dissociating oxygen atoms into oxygen atoms by irradiating ozone with ultraviolet light, and is used for complete oxidative decomposition of organic substances. JP-A-58-165149, JP-A-58-250088, JP-A-62-2621 and the like are inventions made for this purpose.

For example, a conventional resist removing apparatus disclosed in Japanese Patent Application Laid-Open No. 622-2621 in FIG. 11 is composed of an ultraviolet light source (10), an ozone generator (11), and a vacuum chamber (12). This is a photo-assisting method in which light energy is used to generate ozone from oxygen molecules, or ozone is decomposed to generate more active oxygen atoms, and organic compounds are decomposed into carbon dioxide, water, and the like by the oxidizing action. In this case, a mechanism in which a chemical bond is broken by the direct action of ultraviolet light also occurs in parallel to promote the decomposition of the organic compound. (3) is a valve, and (13) is a vacuum pump.

[Problems to be solved by the invention]

However, in the conventional method using ultraviolet light and ozone, even if the concentration of generated oxygen atoms is small and the effect of direct decomposition of the organic compound by ultraviolet rays is combined, the removal rate of the resist which is an example of the organic substance is 2,000 A / min. And it takes a long time to remove the target organic compound.

This is because the emission density of the current ultraviolet light source is at most 0.6 watt / cm
² and the concentration of generated oxygen atoms remains at about 10 ¹³ particlescm ^-3 even if the concentration of supplied oxygen or ozone is increased,
Therefore, the removal rate of organic compounds was limited to 2,000 A / min even if oxygen atoms had high reactivity with organic compounds.

An object of the present invention is to efficiently generate high-concentration oxygen atoms. As a result, it is possible to avoid the limit of the oxygen removal rate of organic substances, which has been seen in the prior art, and to expand the field of use of oxygen atoms. It is an object of the present invention to obtain a method and apparatus for generating an oxygen atom.

[Means for solving the problem]

The method and apparatus for generating oxygen atoms according to the present invention are characterized in that the oxygen-containing gas pressure P in the discharge field is 0.1 to 10 Torr, and the value of the product P · d of the gas pressure P and the distance d between the discharge electrodes is 1 to 1000 Ton.
It is characterized in that an oxygen-containing gas is discharged through a dielectric within a range of rr · cm, and furthermore, a dielectric and an electrode capable of realizing the above conditions are provided.

[Action]

In the present invention, the pressure condition of the discharge field is such that the recombination reaction between oxygen atoms generated by the discharge or the relatively stable ozone generation reaction due to the reaction between oxygen atoms and oxygen molecules prevents the disappearance of oxygen atoms generated by the reaction. ^A high concentration of oxygen atoms up to ¹⁶ particles · cm ^-3 is obtained. Also,
An appropriate distance between the discharge electrodes makes the electric field strength of the discharge field sufficient for dissociation of oxygen molecules, prevents unnecessary ionization of oxygen, and allows oxygen atoms to be obtained with high efficiency.

〔Example〕

 An embodiment of the present invention will be described below.

FIG. 1 is a configuration diagram of an oxygen atom generator according to one embodiment of the present invention. In FIG. 1, (1) is a tubular dielectric made of glass, quartz, ceramic or the like, and (2) is made of a dielectric material such as a metal or an organic conductive material adhered to a dielectric tube. Electrodes, (3) a valve capable of adjusting the flow rate or pressure, (4) a vacuum pump, (5) a reaction chamber, (6) an AC power supply, (7) a high voltage transformer, and (8) a source gas source. It is.

Source gas source (8), regulating valve (3), tubular dielectric (1), reaction chamber (5) and vacuum pump (4)
Forms a series of flow paths, and the oxygen-containing gas supplied from the source gas source (8) flows into the inside of the tubular dielectric (1) through the regulating valve (3). At this time, the pressure inside the tubular dielectric (1) is set to a set pressure range of 0.1 to 1 by the adjusting valve (3).
Adjusted to 0 Torr. A high AC voltage is applied between the two electrodes (2) closely attached to the outside of the tubular dielectric (1),
Producing a discharge in the flowing gas through the tubular dielectric (1);
By this discharge, oxygen molecules in the source gas are excited, and as a result, dissociated into oxygen atoms. The oxygen atoms generated in this manner are introduced into the reaction chamber (5) and are used for oxidation of organic substances and oxidation of inorganic substances such as metals. Oxygen that has not been converted into oxygen atoms in the source gas and gases other than oxygen previously mixed in the source gas are discharged from the reaction chamber (5) to the outside of the system by the vacuum pump (4).

FIG. 2 shows the relationship between the gas pressure of the discharge field and the absolute value and relative value of the generated oxygen atom concentration when oxygen gas is used as a raw material. The absolute concentration indicates the number of oxygen atoms per unit volume under a set pressure, and the relative concentration indicates the ratio of the number of oxygen atoms to the total number of gases. As is apparent from FIG. 2, the relative oxygen atom concentration increases with a decrease in the gas pressure, and shows a substantially equilibrium value at a pressure of 0.1 Torr or less. On the other hand, the absolute oxygen atom concentration increases as the gas pressure decreases, but decreases at a pressure of 3 Torr. Conditions that can supply as much oxygen atoms as possible without increasing the capacity of the vacuum pump require that the relative oxygen atom concentration be high and that the pressure of the supplied gas be low. Further, a high absolute oxygen atom concentration is also required to maintain the oxidation reaction by oxygen atoms at high speed. It can be seen from FIG. 2 that these conditions are satisfied when the pressure of the gas to be discharged, that is, the oxygen-containing gas is limited to the range of 0.1 to 10 Torr. Although FIG. 2 shows the case where the gas to be discharged is oxygen gas, the absolute value (the height of the peak of the curve) in FIG. 2 is small even when oxygen gas contains impurities. The range from 0.1 to 10 Torr is almost unchanged.

FIG. 3 schematically shows the relationship between the product (P · d) of the pressure P of the gas to be discharged and the distance d between the discharge electrodes, the energy efficiency of dissociation (ionization) of oxygen molecules, and the relationship with the discharge sustaining voltage. There is something. When P · d is 1 Torr · cm or less, the electron energy of the discharge is large, and ionization of oxygen molecules occurs, which requires more discharge power than necessary. In addition, ionized oxygen molecules have sufficient energy and therefore exhibit almost the same oxidizing power as oxygen atoms, but they often cause fatal damage to a substance to be treated due to having an electric charge, and thus their generation is not preferable. On the other hand, when P · d is 1000 Torr · cm or more, the electron energy of the discharge is small and sufficient excitation of oxygen molecules cannot be performed, so that generation of oxygen atoms cannot be expected, and the voltage required to maintain the discharge is high and the dielectric constant is high. It is easy to cause dielectric breakdown of the body. From the above results, P · d is 1 to 1000 as the discharge condition.
Torr.cm is an essential condition for efficiently generating oxygen atoms.

FIG. 4 is a partial sectional view showing a main part of an oxygen atom generator according to another embodiment of the present invention. In FIG.
(1) is a tubular dielectric, and (2) is an electrode made of a conductive material such as a metal adhered to a dielectric tube or adhered with a conductive adhesive. One or more electrodes are provided inside the electrode. A through-hole (2A) is provided, and the cooled liquid flows through the through-hole (2A) to maintain the temperature of the discharge gas in an appropriate range via the electrode and the tubular dielectric (1). The energy used for dissociation of oxygen molecules is at most only tens of percent of the power input for discharging, and the rest is converted to thermal energy and used for heating the gas to be discharged. The heated gas heats the contacting tubular dielectric (1). Generally, the dielectric tends to cause dielectric breakdown at a high temperature, and cooling is indispensable to prevent this. For example, when borosilicate glass is used as a dielectric, the dielectric breakdown voltage decreases at 200 ° C. or higher due to the characteristics of borosilicate glass, so that cooling to at least this temperature is essential.

Also, the same effect can be obtained by adding a fin and performing gas cooling through this fin, even if the cooling of the electrode is not a method of flowing the cooled liquid through the through hole (2A) as shown in FIG. Needless to say.

FIG. 5 is a partial sectional view showing a main part of an oxygen atom generating apparatus according to another embodiment of the present invention. In the figure, (9)
Is a temperature control block made of a good heat conductive material such as a metal adhered to the dielectric tube (1) or bonded with a good heat conductive adhesive. The temperature control block (9) has a through hole (9A) through which the cooled liquid can flow, or has a fin outside. By passing the cooled liquid through the through hole (9A) of the temperature control block (9) or by passing the cooled fluid through an external fin, the temperature of the tubular dielectric (1) or the gas to be discharged can be adjusted. To prevent the dielectric breakdown of the tubular dielectric (1).

Incidentally, the configuration of the dielectric and the electrode only needs to satisfy the above-described conditions, and as shown in FIG.
And a structure in which a high voltage is applied alternately. A plurality of tubular dielectrics (1) are bundled as shown in partial sectional views and side views in FIGS. 7A and 7B, and an electrode (2) is provided on the outer periphery thereof. Further, as shown in FIG. 8, even in a configuration in which the tubular dielectric (1) is wound and provided with at least one pair of electrodes (2) to shorten the installation length of the tubular dielectric (1), FIG. , B, the same effect can be expected even in a configuration in which the electrode (2) is opposed to the tubular dielectric (1) as shown in the front view and the cross-sectional view. It is not necessary to provide both of the pair of electrodes (2) at the same time outside the dielectric, and one of them may be in contact with the gas to be discharged.

Further, the grounding of the discharge electrode may be performed by grounding one of the counter electrodes to which a high voltage is applied, another ground electrode may be provided in the middle of the counter electrode, or when a temperature adjustment block is provided between the electrodes. This temperature adjustment block may also serve as a ground electrode.

Furthermore, when ozone-containing oxygen is used as a source gas, ozone is easily decomposed to generate oxygen atoms, so that a higher concentration of oxygen atoms can be obtained than when oxygen is used as a raw material. FIG. 10 is a schematic configuration diagram of an oxygen atom generating apparatus showing an embodiment in which an ozone-containing gas is used as a raw material. In the figure, (11) is an ozone generator. Source gas source (8)
The oxygen-containing gas supplied from the ozone generator (11)
And a part of the contained oxygen is converted to ozone and sent to the tubular dielectric (2). Subsequent operations generate the same oxygen atoms as in the apparatus of FIG.

For reference, an oxygen-containing gas has been described above as a raw material gas. However, by using a gas other than oxygen as a raw material, a desired atomic gas can be obtained by the apparatus of the present invention. For example, when nitrogen is used as a source gas, nitrogen atoms can be efficiently obtained at a high concentration.

〔The invention's effect〕

As described above, according to the present invention, when the oxygen-containing gas pressure of the discharge field is 0.1 to 10 Torr, and the product of the oxygen-containing gas pressure and the distance between the discharge electrodes is 1 to 1000 Torrcm, the dielectric Since the discharge is performed on the oxygen-containing gas through the target, there is an effect that high-concentration oxygen atoms can be efficiently generated.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an oxygen atom generating apparatus according to one embodiment of the present invention, and FIG. 2 shows the relationship between the pressure of the gas to be discharged and the absolute and relative concentrations of generated oxygen atoms according to one embodiment of the present invention. FIG. 3 is a characteristic diagram showing the relationship between the product of the pressure of the gas to be discharged and the distance between the electrodes, the energy efficiency of oxygen molecule dissociation, and the discharge sustaining voltage. FIGS. 7A and 7B are a partial sectional view and a side view, respectively, showing main parts of an oxygen atom generator according to another embodiment of the present invention. FIG. 9 is a perspective view showing a main part of an oxygen atom generator according to another embodiment of the present invention. FIGS. 9A and 9B are front views showing main parts of an oxygen atom generator according to another embodiment of the present invention. FIG. 10 is a sectional view of an acid according to another embodiment of the present invention. Diagram showing an atomic generator, FIG. 11 is a schematic diagram of an oxygen atom generator according to a conventional ultraviolet irradiation. In the figure, (1) is a tubular dielectric, (2) an electrode, (2A)
Is a through hole, (3) is a valve, (4) is a vacuum pump,
(5) is a reaction chamber, (6) is an AC power supply, (7) is a high voltage transformer, (8) is a source gas source, (9) is a temperature control block, (9A) is a through hole, and (10) is ultraviolet. Light source, (1
1) is an ozone generator, and (12) is a vacuum chamber. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (2)

(57) [Claims] A method for producing atomic oxygen by discharging an oxygen-containing gas as a raw material through a dielectric, wherein the pressure of the oxygen-containing gas is 0.1 to 10 Torr, and the pressure of the oxygen-containing gas and the discharge electrode A method for generating oxygen atoms, wherein the product of the distance and the distance is 1 to 1000 Torr · cm. A pair of electrodes facing each other, a dielectric interposed between the electrodes and electrically coupled to at least one of the electrodes;
A means for adjusting the pressure of the oxygen-containing gas supplied between the electrodes, and an oxygen atom that dissociates oxygen into oxygen atoms by alternately applying a high voltage to the electrodes and discharging the oxygen-containing gas. In the generator, the pressure adjusting means and the interelectrode distance are set so that the pressure of the oxygen-containing gas is 0.1 to 10 Torr, and the product of the pressure of the oxygen-containing gas and the interelectrode distance is 1 to 1000 Torrcm. An oxygen atom generator characterized in that: