JPS6116502B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for reducing an article and to an apparatus used to carry out the method.

2. Description of the Related Art Attempts to perform various surface treatments by irradiating an object to be treated with an activated gas obtained using plasma generated by vacuum discharge are already known. In this method, activated gas introduced into a reaction chamber located far away from the plasma region is applied to, for example, a semiconductor substrate to perform surface treatments such as etching. It is extremely useful in that it sprays gas.

The present invention changes the concept from the treatment using activated gas as described above, and provides a reduction method capable of reducing the object to be reduced at high temperature and preventing oxidation, and a processing apparatus used to carry out this method. be. That is, the feature is that the workpiece is directly exposed to plasma excited by microwaves, thereby raising the temperature to a high temperature, and then immediately cooled under an inert gas atmosphere.

The embodiment will be explained below with reference to FIG. An exhaust system 110 is connected to accommodate the object to be processed 106 at a predetermined position, and a reaction chamber 105a, a plasma generation tube 105 made of a dielectric material such as quartz, gas flow rate control valves 103 and 104, a hydrogen gas source 101, and an inert A gas source 102 is provided in communication. As a result, hydrogen gas is supplied to the reaction chamber 105a and the plasma generation tube 105 so as to maintain a predetermined degree of vacuum (in the range of 10 ^-2 to 10 Torr). In this case, lid 1
Needless to say, the reaction chamber 105a and the plasma generating tube 105 are kept airtight by the gasket 07 and the gasket 116. The object to be processed 106 is arranged close to the plasma generating section 105b at a distance of 20 cm or less, thereby directly exposing the object to be processed 106 to a plasma region excited by microwaves. The plasma generation tube 105 passes through a microwave cavity 114 made of a rectangular waveguide, and is supplied with microwave power generated by a microwave oscillator 111. Matching device 112 and sliding short circuit plate 1
14a is for efficiently absorbing the microwave power into the gas introduced into the plasma generating tube 105, and is adjusted to the optimum state while checking the degree of absorption of the microwave power with the indicator 113a of the power monitor 113. The activated reaction gas is discharged from the exhaust device 1.
10, and during the suction, it hits the object to be treated 106 and undergoes a reduction process. After the reduction by hydrogen plasma is completed, the flow control valve 103 is closed, and an inert gas such as nitrogen gas, helium, argon, etc. is introduced from the supply source 102 into the reactor 105 by opening the valve 104 to immediately cool the object 106. I'm starting to do that. Note that a microwave shield member 115 is provided around the reaction chamber 105a.

In order to process the object 106 using the above-described apparatus, the object 106 is placed in the reaction chamber 105a.
The gasket 116, lid 105a, etc. are depressurized to 10 ^-2 to ^{10 -1} Torr. Hydrogen gas, which is a reducing gas, is fed into the plasma generation tube 105 from the hydrogen gas source 101 and adjusted by the flow rate control valve 103 so that the pressure inside the plasma generation tube 105 is 10 to 10 ^-1 Torr. Valve 104 is closed to prevent inert gas from entering. Thereafter, the microwave oscillator 111 is operated to generate microwave power, which is transmitted into the microwave cavity 114 and the plasma generation tube 105.
to excite hydrogen gas. Naturally, the indicator 113 of the power monitor 113 is adjusted so that the reflected power is minimized by the sliding short circuit plate 114 and the matching box 112.
Adjust while watching a. As a result, the gas in the plasma generation tube centered around the plasma generation section 105b is turned into plasma, and the light is emitted in a whitish pink color in appearance. This plasma region also extends into the reactor 105a and also extends somewhat in the direction of the gas supply. In this way, the object to be processed 106 is placed in the plasma region, heated to a high temperature, and reduced by the activated gas in the plasma.

Immediately after the reduction treatment of the object 106 is completed, the supply of microwave power and hydrogen gas is stopped, and at the same time the valve 104 is opened to supply inert gas to the reaction chamber 1.
05 and applied to the object to be processed 106 and cooled down to below the oxidation temperature. After the processing is completed, the gas supply is stopped, the exhaust device 110 is stopped, the leak valve 108 is opened, the inside of the reaction chamber 105 is brought to atmospheric pressure, the lid 107 is opened, and the object to be processed 106 is taken out.

The present invention utilizes the device of the present invention as described above,
For example, when we treat oxidized copper pipes,
With a microwave output of 1350W at 2450MHZ, a hydrogen gas pressure of 1Torr in the plasma generation tube, and a processing time of 90 seconds, the color temperature of the copper pipe in the reaction chamber reached approximately 800℃. After the hydrogen plasma was stopped, nitrogen gas, an inert gas, was supplied to quickly cool the pipe to below the oxidation temperature (80°C), and the copper pipe was completely reduced.

In this way, by using the apparatus of the present invention for reduction treatment, the plasma generation tube can also be used as a cooling inert gas supply tube, so the apparatus can be made more compact. In addition to being able to perform reduction using activated gas, the object to be processed is cooled using inert gas, so there is almost no reoxidation after reduction processing. It should be noted that high-temperature hydrogen furnaces used for general reduction processing have the risk of explosion upon ignition, and tend to take a long time to rise to the processing temperature and to cool down after completion of the work. On the other hand, the method of the present invention has the advantage that there is no danger during ignition, and the time required to reach the processing temperature and the time required for cooling is very short, allowing rapid processing.

The apparatus shown in FIG. 2 is suitable for continuous processing of a thin wire 106, and has an inlet and an opening at both ends of a plasma generating tube 105, which also functions as a reaction chamber, through which the wire 106 can run in the direction of arrow 120 while keeping airtight. 121, 122, a heat-resistant partition wall 123, and a cooling chamber 124 are integrally and continuously provided. Reduction raw material gas is introduced from the left side of the plasma generation tube 105 and discharged near the partition wall 123, and inert gas can be introduced into the cooling chamber and is discharged from the right side. It's summery.
As a result, the wire is connected to the plasma generating part 105b.
Because it passes through directly, it is efficiently heated to high temperatures and reduced. Then, it is immediately exposed to an inert atmosphere in a cooling chamber and cooled. Therefore, it is ideal for continuous processing.

The apparatus of the embodiment shown in FIGS. 3 and 4 is suitable for continuous processing of sheet materials. In this device, a closed cylindrical reaction chamber 105a is provided in continuous proximity to a plasma generation tube, and a cooling chamber 124 is further provided in connection with this. Exhaust devices 110, 110 are independently connected to each. The two are separated by a heat-resistant partition wall 123. The sheet material 106 is moved through the plasma region in the direction of arrow 120 and subjected to reduction treatment in the same manner as described above. According to this apparatus, even a wide sheet-like material can be sufficiently processed, and even if the material is a conductor, stable processing can be performed without any influence on the microwave electric field of the plasma generation part.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention;
FIG. 2 is a sectional view of main parts showing another embodiment of the present invention;
FIG. 3 is a top view of the main part showing still another embodiment, and FIG. 4 is an enlarged sectional view of the main part. 101... Raw material gas source, 102... Inert gas source,
105a...Reaction chamber, 105...Plasma generation tube, 1
06...Processed object, 110...Exhaust device, 114...Microwave cavity, 111...Microwave oscillator, 10
5b...Plasma generation section, 124...Cooling chamber.

Claims (1)

[Claims] 1. A method of exposing a material to be reduced to a plasma region excited by microwaves to perform high-temperature treatment, and then feeding an inert gas into the plasma region to cool the material to be reduced. Characteristic reduction method. 2. The reduction method according to claim 1, wherein the plasma is hydrogen gas excited by microwaves. 3. A microwave oscillator, a microwave cavity connected to the oscillator, a plasma generation tube arranged to pass through the cavity and into which source gas is introduced, and a plasma generation tube in communication and proximity to the plasma generation tube. a reaction chamber in which a substance to be reduced is accommodated; and an inert gas cooling chamber provided integrally with or connected to the reaction chamber so that an inert gas can be selectively introduced into the reaction chamber. A processing device comprising: