JPH0695500B2 - Microwave plasma processing method and apparatus - Google Patents

Description

DETAILED DESCRIPTION [Outline] The input to the magnetron is a pulse wave, and the traveling wave is monitored and the pulse width is automatically changed so that the output becomes constant, and the plasma is kept constant. A microwave plasma processing method and apparatus are provided.

[Industrial application field]

The present invention relates to a microwave plasma processing method and apparatus.

[Conventional technology]

Dry etching technology tends to be frequently used in the manufacture of semiconductor integrated circuit devices, and one of them is a microwave plasma etching method. An apparatus therefor is shown in a schematic cross-sectional view in FIG. 3, in which the central discharge chamber 31 is vacuum-sealed with a dielectric (quartz or alumina) discharge tube 32 for passing microwaves, and the discharge chamber 31 is placed below the discharge chamber 31. Is arranged so that the sample 33 is electrically insulated, a mirror magnetic field is applied from the discharge chamber 31 to the sample 33 by the solenoid coil 34 and the permanent magnet 35,
The discharge chamber 31 and the etching chamber 36 are evacuated to a high vacuum, the etching gas is introduced from the gas introduction pipe 37 at a predetermined gas pressure in the direction of the arrow, and the 2.45 GHz microwave generated by the magnetron 38 is a rectangular waveguide 39. Discharge chamber through a circular waveguide 40
Introduced in No. 31, microwave discharge is generated (Takuo Sugano, Semiconductor Plasma Process Technology, 1980, Sangyo Tosho, page 139). In the figure, air introduced from the inlet 41 (indicated by an outlined arrow) is guided to the outside from the end portion of the circular waveguide 40 as indicated by an outlined arrow, and the etching chamber is exhausted from the exhaust port 42. .

[Problems to be solved by the invention]

When plasma is generated by microwaves, the traveling wave power is not fed back to the power source and load variations to make the traveling wave power constant. On the other hand, such feedback was used in communication technology, etc., but it changed the peak current of the input. However, oscillation with a high peak is not preferable because it causes arc discharge and the like. There is also a problem that the load of plasma is severely changed and the life of the magnetron is not long.

The fluctuation of the microwave power source is caused by the deterioration of the magnetron and the fluctuation of the building power source at the installation site. If you try to cover it by changing the peak current and raise the peak value too high, there is a risk that discharge may occur in places with poor contact in the waveguide or in the protruding parts of the vacuum processing chamber (chamber). It is easy to break, so it is not preferable to deal with the power supply fluctuation by the change of the peak current.

The present invention was created in view of the above circumstances, and an object of the present invention is to provide a microwave plasma processing method and apparatus in which plasma processing is stable and the life of the magnetron is extended.

[Means for solving problems]

The above-mentioned problems are caused by inputting a pulse wave generated by a magnetron power supply 15 into a magnetron 14 that oscillates a microwave, and a directional coupler 16 in which a micro traveling wave is provided in a waveguide 11.
The result of such monitoring is fed back to the magnetron power supply 15, and the peak value of the pulse output from the magnetron power supply 15 is fixed to a predetermined value so that the output of the magnetron 14 becomes constant. Microwave processing method characterized by changing to
And magnetron 14, waveguide 11, microwave transparent window
In a microwave plasma processing apparatus including a processing chamber 13 and a processing chamber 13, a magnetron power source 15 for outputting a pulse wave is connected to the magnetron 14, and a directional coupler 16 arranged in the waveguide 11 for monitoring a microwave traveling wave is provided. Feedback line
By connecting to the first grid power supply (bias pulse) 22 of the magnetron power supply 15 by 17 and fixing the peak value of the pulse to a predetermined value, only the pulse width is automatically changed so that the output of the magnetron 14 becomes constant. It is solved by providing a microwave plasma processing apparatus characterized by:

[Action]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a block diagram of a magnetron power supply of the apparatus shown in FIG.

In FIG. 1 and FIG. 2, the input to the magnetron 14 is performed by a pulse wave, and the result of monitoring the micro traveling wave by the directional coupler 16 is fed back to the magnetron power supply 15 so that the output of the magnetron 14 becomes constant. Automatically change the pulse width.

In the present invention, the input to the magnetron for generating the plasma is a pulse wave, the traveling wave oscillated by the magnetron is monitored by the directional coupler, the value on the incident wave side is fed back to the magnetron power supply, and the pulse width is changed. It automatically changes so that a constant traveling wave can always be obtained, and the output from the magnetron is made constant even if there are load fluctuations, deterioration of the magnetron, voltage drop of the building power supply, etc.

〔Example〕

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

FIG. 1 is a sectional view showing an apparatus used for carrying out the method of the present invention, in which 11 is a waveguide, 12 is a microwave transmission window, 13 is a processing chamber, 14 is a magnetron, and 15 is a magnetron. A power supply, 16 is a directional coupler.

In the use of the apparatus shown in FIG. 1, the input to the magnetron 14 for generating plasma is a pulse wave, and the micro traveling wave oscillated by the magnetron 14 is monitored by the directional coupler 16 to obtain information obtained as a feedback line. At 17, feedback is made to the magnetron power supply 15, and the pulse width of the pulse wave supplied from the power supply 15 to the magnetron 14 is changed so that a constant traveling wave is always obtained.

The configuration of the magnetron power supply 15 is shown in FIG. 2, which includes a (3 to 5.5 KV) DC power supply 21, a first grid power supply (bias pulse) 22, a second grid power supply (bias) 23, and a quadrupole heater power supply 24. , Heater power supply 25 for magnetron, sequencer relay circuit and protection circuit 26, constant current circuit (quadrupole tube) 27, DC power supply 21 arranged in parallel from sequencer relay circuit and protection circuit 26 AC20
Power is supplied from 0V3φ (or AC220V3φ) power supply 29,
DC power supply 21, first grid power supply 22, second grid power supply 23,
A pulse wave is supplied to the magnetron 14 from a constant current circuit 27 connected to the heater power supply 24.

From the experiment using the apparatus shown in FIG. 1, it was confirmed that the stability of the plasma treatment was increased and the life of the magnetron was extended to about 3 to 5 times.

〔The invention's effect〕

As described above, according to the present invention, in the microwave plasma processing, it is possible to keep the output of the magnetron constant by automatically changing the pulse width of the pulse wave input to the magnetron. The treatment is stable, and it is effective in extending the life of the magnetron.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, FIG. 2 is a block diagram of a magnetron power supply, and FIG. 3 is a sectional view of a conventional microwave plasma etching apparatus. 1 and 2, 11 is a waveguide, 12 is a microwave transmission window, 13 is a processing chamber, 14 is a magnetron, 15 is a magnetron power supply, 16 is a directional coupler, 17 is a feedback line, and 21 is DC power supply, 22 first grid power supply, 23 second grid power supply, 24 quadrupole heater power supply, 25 magnetron heater power supply, 26 sequencer / relay circuit and protection circuit, 27 constant current circuit, 28 It is a detection amplifier.

Front page continued (72) Inventor Shozo Noda 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (56) References JP-A-59-171491 (JP, A) JP-A-60-126835 (JP) , A) JP-A-53-29672 (JP, A) JP-A-60-16424 (JP, A) JP-A-61-241922 (JP, A)

Claims (2)

[Claims] 1. A magnetron (14) for oscillating microwaves
The input to the magnetron power supply (15) is generated by the pulse wave, the micro traveling wave is monitored by the directional coupler (16) provided in the waveguide (11), and the result of the monitoring is monitored by the magnetron power supply (15). ), The peak value of the pulse output from the magnetron power supply (15) is fixed to a predetermined value and only the pulse width is automatically changed so that the output of the magnetron (14) becomes constant. Microwave treatment method. 2. A microwave plasma processing apparatus comprising a magnetron (14), a waveguide (11), a microwave transmission window (12) and a processing chamber (13), which outputs a pulse wave to the magnetron (14). The directional coupler (16) connected to the magnetron power supply (15) and monitoring the micro traveling wave arranged in the waveguide (11) is connected to the first grid power supply (15) of the magnetron power supply (15) by the feedback line (17). Bias pulse) (22), the peak value of the pulse is fixed to a predetermined value, and only the pulse width is automatically changed so that the output of the magnetron (14) becomes constant. Processing equipment.