JPH046267A - Microwave plasma treating device - Google Patents

Abstract

PURPOSE:To stably output high reliable and high-velocity impulsive microwaves by forming the microwave generating means of the plasma treating device which generates plasma by microwaves and execute a surface treatment into a specific construction. CONSTITUTION:The microwave oscillator 1, as represented by an electromagnetic tube, etc., in the plasma treating device which generates the plasma by using the microwaves and execute the surface treatment is driven by a microwave source driving section 10 and the generated microwave electric power is inputted through a waveguide 13 then through glass 20 for vacuum sealing into a reaction chamber 14 to generate the plasma in the chamber. A sample 15 is subjected to the etching surface treatment by this plasma. The microwave generating means is constituted of the microwave generator 1, a filament circuit including a power source 4, a high-voltage constant current power source 2', and a current switching section 5 between the output thereof and a filament circuit for microwave oscillation to stably output the high-velocity impulsive microwaves.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to plasma processing equipment that generates plasma using microwaves and performs etching, deposition, polymerization, oxidation, sintering, surface modification, etc. In particular, the present invention relates to a plasma processing apparatus equipped with suitable plasma generating means for use in each of these processing apparatuses.

[Conventional technology]

2. Description of the Related Art Conventionally, as a method for plasma processing an object to be processed such as a semiconductor wafer, a method has been known in which a microwave is used to generate a buzzing plasma. As a method for further improving the second plasma processing performance, a method of applying microwaves in the form of pulses is also described in Japanese Patent Laid-Open No. 1-21422.

[Problem to be solved by the invention]

In the above-mentioned prior art, there is no difference in the method of pulsing microwaves.

A magnetron is generally used as a source of microwaves.

FIG. 1 shows the high voltage flow (I)-high voltage (V) characteristics of the magnetic tube. The microwave output power is almost proportional to the high voltage current, and the microwave output power is
As stated in Publication No. 2, when turning on/off, switching is performed between points A and B in FIG. In this case, the magnetic tube has a large voltage change of O←VH for every l pulse and ON10 F F of microwave oscillation.
will be repeated.

By the way, when the magnetic tube turns the oscillation from OFF to ON,
It has a tendency to deteriorate due to abnormal mode oscillation, etc.
If ON/OFF is repeated in short cycles, the life of the magnetic tube will be significantly shortened (there was a drawback that 0) Also, since a large voltage change occurs with each pulse, there is The light/discharge of the filter capacitor (several hundred picofarads) [fL increases,
Rapid change was difficult.

As the second factor, 100 examples of conventional drive power sources for magnetron tubes 1 are shown. Filament electric #4. Current detector 3. It consists of a high voltage control power source 2, and the voltage fLHk output 7g3 and the high voltage control IE source 2 constitute a high voltage constant current power source #2'. High voltage constant current power supply 2
The output of ' is connected to one side of the filament circuit. It is possible to obtain pulsed microwave output by adding an ON/OFF pulse repetition signal as a setting signal for the high voltage control power supply 2, but as mentioned earlier, the lifetime of the magnetic tube is short and the response is fast. There was a drawback that it was difficult to

An object of the present invention is to provide a microwave plasma processing apparatus capable of generating highly reliable pulsed microwaves.

[Means to solve the problem]

In order to achieve the above object, a pulsed microwave generation means, a transmission means for introducing the microwave from the microwave generation means into a reaction chamber, and a gas supply means and an exhaust means connected to the reaction chamber are provided. , and four INCI units installed in the reaction chamber, and generates plasma in the reaction chamber to process a sample,
The microwave generating means is a microwave generator for generating microwaves.

It is composed of a microwave generator filament circuit, a high voltage constant current circuit, and a current switching section provided between the output of the high voltage constant current circuit and the microwave generator filament circuit.

[For production]

As described above, a current switching section is provided between the high voltage constant current circuit for the magnetic tube (microwave generator) and the electric tube filament circuit, and the current is changed between the high level potential and the low level potential at a predetermined synchronization. As a result, the oscillation of the &f'WL tube is not interrupted, and changes in the voltage applied between the anode and cathode of the magnetron tube are reduced, making it possible to output pulsed microwaves at high speed and with high reliability. This makes it possible to perform highly reliable and high-performance plasma processing using this technology.

In other words, by changing the high-voltage current applied to the magnetic tube (microwave generator) between high and low levels, the oscillation of the magnetic tube is not interrupted, and the change in the high voltage applied to the magnetic tube is minimized. This will greatly extend the longevity of the old man.

Here, the high voltage current I at the high output level of the microwave
By setting the ratio IL/IH of the high voltage current It at the low output level of the microwave (point C in Figure 1) to H (point C in Figure 1), the pulse property can be improved. Stable operation of the magnetron tube can be achieved without losing the process performance improvements made by microwaves. IL/IH is 1/2
Below oo, it is difficult for the magnetic tube to operate stably, and the IL
When /IH is 1/3 or more, the improvement in process performance by pulsed microwaves is significantly lost.

Further, as shown in Fig. 3, a current switching unit 5 is provided between the output of the high voltage constant current power supply 2' and the filament circuit of the magnetic tube. A low-level current control circuit 6 that flows a high-level current and a high-level current control circuit 7 that flows a high-level current are provided in parallel, and at least the high-level current control circuit 7 has an ON10 at a predetermined pulse period.
It has a function to perform F
Set IH to 1/3 to 1/3.

In addition, ON10 FF in the high level current control circuit 7,
FIG. 5 shows the anode voltage (V) waveform and anode current (1) waveform of the magnetic tube.

Although we have described the case where there are two levels of ttiL flowing through the magnetic tube, even when using three or more levels of current, the lowest level current and highest level current are the same as the above-mentioned high level current and low level current. Of course, if it has the properties, it is included in the present invention.

〔Example〕

An embodiment of the present invention is shown in FIG. 6 below.

The magnetic tube 1 is supplied with filament current by a filament electric current j14. A current switching section 5 is provided between the output of a high voltage constant current power supply 2' consisting of a current detector 3 and a high voltage control voltage #2 and the filament circuit. The current switching section 5 includes a high-level current control circuit 7 that turns on/off a high-level current by a pulse generating section 8, and a low-level current control circuit 6 that sets a low-level current. A high voltage capacitor 9° is installed to match the current switching unit 5 which controls current changes at high speed and the high voltage constant current power supply 2' which controls average current at relatively low speed. Although the high-voltage capacitor 9 can be built into the high-voltage constant-current power supply 2', it is preferably installed near the high-level current control circuit 6 because it absorbs pulsed current.

Low level current control circuit6. High level current control circuit7. An actual example of the pulse generator 8 is shown in No. 7 (2). The low level current control circuit 6 is composed of a resistor 6a. The high level current control circuit 7 is composed of a high voltage MOS transistor 7a, a surge absorbing element 7b, and a resistor 7C. Note that the resistor 7C can also be omitted by utilizing the internal resistance of the magnetic tube l itself.

The signal from the pulse signal ffi8a is amplified by a transistor, then inputted to the primary side of the isolation transformer 7d, and an insulated pulse output is output from the secondary side of the transformer 7d. In addition to the connection between the sources, the high voltage MO8 transistor 7a is turned on/off.

FIG. 7 shows a high voltage MOS transistor 7a that stores the current during the OFF period of the high voltage MOS transistor 7a in a capacitor 7e.
The power supply for the gate circuit of transistor 7a is omitted. Note that a capacitor U is installed between the filament circuits in order to prevent abnormal voltage from occurring between the filaments when switching high-voltage currents.

Further, FIG. 8 shows another example of the high voltage level current control circuit 7 and pulse generator 8 in FIG. 6. By using a light-emitting diode and a light-excited MOS transistor 7f, which has the function of activating the MO8h run transistor 10FF by this light and the function of insulating between the light-emitting diode and the MOS transistor, pulses can be generated with a simple configuration by inputting a signal from the pulse source signal source 8a. The generating section 8 and the high level [fi control circuit 7] can be configured.

An example of operation is shown below.

1H=l)QQaλIL =10 +aA IL
=IH=1/60vH=4xv, vH-VL=200V
, Frequency: 2.45 GHzTR=500p8.
The optimal values of TIy=100, 11TR, and Tw vary greatly depending on the process conditions used.

An example of a plasma processing apparatus to which the microwave source driving section 10 shown in FIGS. 6 to 8 is applied is shown in FIGS. 9 and 10.

A microwave source drive unit IO drives a microwave [1 represented by a magnetron, etc., and the generated microwave power is passed through a waveguide B, through a vacuum sealing glass X, and then into a reaction chamber 14.
is input. A sample chamber for processing is installed in the anti-seed chamber, and is connected to a gas supply section and an exhaust device 17. In order to efficiently generate plasma with low gas pressure, the magnetic field coil 16 is used to generate electron cyclotron resonance 1.
GB) may occur. In addition, there are cases where a resonator for resonating microwaves is configured in a part of the waveguide 13 or the reaction chamber 14, and in the filo diagram, a reflector plate is installed for that purpose. This will be explained with reference to FIG. FIG. 11 is a diagram when a plurality of magnetic tubes are used to improve process performance. It consists of a plurality of magnetic tubes 1a, Lb, a plurality of filament power supplies 4a, 4b, a plurality of current switching parts 5a, 5b, and one high voltage constant current electric current jli2'. Magnetic tube 1m
The output is input to waveguide B' via waveguide 13a. Similarly, the output of the magnetic tube 1b is input to the waveguide 13' via the waveguide L3b.

By making the phase of the current pulse generated by the current switching section 5a and the phase of the current pulse generated by the current switching section 5b different, a single high voltage constant current power source can be used for a plurality of magnetrons. High-voltage constant-current power supplies are expensive, so being able to reduce their number is a big advantage.

Although a magnetron has been described as a microwave source, the present invention can be similarly applied to cases where other microwave sources are used.

〔Effect of the invention〕

According to the present invention, a highly reliable and high-speed pulsed microwave output can be obtained, so a highly reliable and high-performance plasma processing apparatus can be obtained.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the magnetron tube driving section of the microwave plasma processing apparatus of the present invention, Fig. 2 is a block diagram of the current switching section of the microwave plasma processing apparatus of the present invention, and Fig. 3 is the voltage applied to the magnetron tube. - Current pulse pattern diagram, Figures 1 and 4 are configuration diagrams showing an embodiment of the present invention combining Figures 1 and 2, Figure 5 is a configuration diagram showing details of Figure 4, and Figures 9J6 and 9J6 are FIG. 4 is a configuration diagram showing another embodiment of the high-pressure level IE flow control circuit and the pulse generation section; FIGS. 187 to 9 are diagrams showing configuration examples of the microwave plasma processing apparatus of the present invention;
FIG. 0 is a diagram showing the characteristics of a magnetic tube, and FIG. 11 is a configuration diagram showing a conventional magnetic tube drive section. l...Magnetic tube, 2...High voltage control power supply,
2'... High voltage constant current power supply, 4... Filament power supply, 5... Current switching unit, 6...
...Low level current control circuit, 7...High level current control circuit, 10...Microwave source drive section, super...
...Waveguide, 14...Reaction chamber, 17...
...Exhaust equipment, field...-Katsuo Ogawa, Patent Attorney, Gas Supply Department Agent-Electricity. Ono diagram 42 Figure / 7

Claims (1)

[Claims] 1. A pulsed microwave generating means, a transmitting means for introducing the microwave from the microwave generating means into a reaction chamber, and a gas supply means and exhaust means connected to the reaction chamber. and a sample stage provided in the reaction chamber, and the plasma processing apparatus processes a sample by generating plasma in the reaction chamber, wherein the microwave generation means includes a microwave generator n for generating microwaves, a microwave generator n for generating microwaves, A microwave plasma processing apparatus comprising: a wave generator filament circuit; a high voltage constant current circuit; and a current switch provided between the output of the high voltage constant current circuit and the microwave generator filament circuit. 2. The plasma processing apparatus according to claim 1, wherein the microwave plasma has a pulse current generation circuit that is turned on and off at a predetermined period in parallel with a circuit for setting the minimum current as a predistribution current switching section. Processing equipment. 3. In the plasma processing apparatus according to claim 1, the lowest current (I
_L) to the maximum current (I_H) (I_L/I_H)
A microwave plasma processing apparatus in which the ratio is 1/200 to 1/3. 4. The plasma processing apparatus according to claim 1, wherein the microwave plasma has a plurality of microwave generators, a plurality of microwave generator filament circuits, a plurality of current switching sections, and one high voltage constant current circuit. Processing equipment. 5. A microwave plasma processing apparatus in which a high voltage capacitor is installed in the current switching section in the plasma processing installation according to claim 1. 6. The microwave plasma processing apparatus according to claim 1, wherein the response time constant of the high voltage constant current circuit is longer than the period of the current pulse generated by the current switching section.