JPS6134942A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To upgrade the production efficiency of plasma by a method wherein reaction gas is made to blow off in a direction, which is parallel to the progressing direction of the micro wave in the waveguide, in a beam form. CONSTITUTION:Reaction gas is made to blow off in a waveguide 1 from a gas channel 2 and a beam 5 is formed. The reaction gas to blow off in a beam form is mainly brought into a plasmic state at the position of the loop of the electric field of micro wave in the waveguide 1, spreads in the interior of the waveguide 1 sectioned by a partition 3, the neutral gas including active species passes through an opening 6 and is guided into a plasma treating chamber 4. By this way, there is no need to match the position of the loop of the micro wave, the operation is simplified, and moreover, the rematching of the position can be dispensed with to a change of the impedance due to a modification of gas species and so forth.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus, and particularly to an improvement in a plasma processing apparatus in which plasma is generated stably with high efficiency using microwaves.

In the manufacturing process of semiconductor integrated circuit devices (hereinafter abbreviated as IC), the plasma process enables dry and low-temperature processes, and is suitable for finer patterns. )
It is widely applied to

In these processes that apply plasma, it is desired that plasma be generated stably and with high efficiency.

[Conventional technology]

To generate plasma, the required gas is placed in a vacuum container at, for example, 0. Introducing at a pressure of about 10 Torr to 10 Torr,
An electric field is applied to this. Free electrons that receive energy from the electric field collide with gas molecules or atoms, and in the case of elastic collisions, the kinetic energy of the neutral particles increases, but in the case of inelastic collisions, the internal energy of the gas molecules increases. excitation and dissociation.

Ionization occurs and a plasma state is formed.

Microwaves are often used in the electric field to generate this plasma. FIG. 2(a) is a schematic diagram showing a conventional example of an apparatus for exciting plasma by microwaves.

In the microwave oscillator 2, a microwave of 2.45 GH2 is normally generated by a magnetron, and this microwave is guided to the isolator 12. The isolator 12 allows the incident wave to pass through, but the reflected wave that returns due to mismatch is 90°
is deflected and absorbed by the pseudo load. Also, directional coupler 1
The power of the incident wave 1 and the reflected wave is monitored through 3.

A quartz tube 17 is inserted in the electric field direction of the microwave TEo mode waveguide 15, and gas is introduced into which quartz tube 17.
6, the antinode of the electric field 7 is aligned with the position of the quartz tube L7. Note that 18 is a cooling device.

In addition, in the conventional example shown in Fig. 2 ω), a partition wall 9 made of quartz or alumina, etc. is provided in the waveguide 15 to cut off the gas, and the gas is introduced into the waveguide 15. However, in this method as well, the antinode of the electric field of the microwave shown by diagonal lines where the gas flow is strong and the pressure is high is matched by the short-circuit plunger matching device 16 or the like.

The microwave matching described above is necessary to minimize the reflected waves and maximize plasma generation efficiency.

[Problem that the invention seeks to solve]

In plasma generation using microwaves in plasma processing equipment as explained above, tuning is performed to match the antinode of the microwave's electric field to the gas flow, but if the impedance changes due to a change in gas type, etc., the tuning must be done again. It is necessary to do this.

This not only reduces the workability of the plasma processing apparatus, but also complicates the microwave matching means of the plasma processing apparatus.

Note that when the gas pressure is about 2 Torr or less, the microwave absorption efficiency decreases, and microwave matching becomes even more important.

[Means for solving problems]

The above-mentioned problem is solved by the plasma processing apparatus according to the present invention, which generates plasma by blowing out a reactive gas in a beam shape in a direction parallel to the direction of propagation of microwaves at the internal pressure of a waveguide in which microwaves are propagated.

[Effect]

The plasma processing apparatus of the present invention has a structure in which a required reaction gas is blown out in a beam shape in a direction parallel to the direction of microwave propagation within a waveguide. However, the blowing direction of the gas may be the same as or opposite to the direction of incidence of the microwave.

The blown gas beam travels in the blowing direction to a long length, forming a state of higher density and higher pressure than its surroundings. Therefore, this gas beam passes through the antinode part where the electric field of the microwave is maximum, and plasma is generated here with high efficiency.

There is no need to adjust the position of the antinode even if the impedance changes due to a change in gas type and the microwave wavelength expands or contracts.

Further, the beam portion has a higher pressure than the plasma processing pressure, and when the pressure is about 2 Torr or less, an effect of improving efficiency can be obtained.

〔Example〕

The present invention will be specifically explained below by referring to an embodiment whose schematic cross-sectional view is shown in FIG.

In the figure, l is a microwave waveguide, 2 is a gas conduit, and 3 is a microwave waveguide.
4 indicates a partition wall, and 4 indicates a plasma processing chamber. A beam 5 as shown by the arrow is formed. Further, in this embodiment, microwaves having a frequency of 2.45 GH2, for example, pass through the partition wall 3 and simultaneously enter the gas outlet.

The reactant gas blown out in a beam shape turns into plasma mainly at the antinode of the electric field of the microwave and spreads into the waveguide l separated by the partition wall 3, and the neutral gas containing active species passes through the opening 6. It is guided into the plasma processing chamber 4.

A gas prepared by adding about 20% oxygen (02) to carbon tetrafluoride (CF'4') used for etching silicon (St) was blown into the apparatus of this example as described above, and plasma processing was performed. The pressure in the room is about 0.5 Torr.

When microwaves of 2.45 GHz and L KW are matched to the apparatus of this embodiment, the reflected waves of the gas are about 22 to 30%. In the conventional device shown in FIG. 2(a), the reflected waves reach approximately 45 to 55 inches even if the above-mentioned matching is performed, whereas this embodiment achieves a significant efficiency improvement. [Effects of the Invention] As explained above, according to the present invention, there is no need to align the position of the microwave antinode of the microwave plasma processing apparatus, and the operation is extremely simple and time-consuming, and it is easy to change the gas type, etc. does not require rematching due to impedance changes.

Further, the efficiency improvement of microwave power is particularly remarkable when the power is about 2 Torr or less. Therefore, plasma is generated stably with high efficiency and can contribute to plasma processes for semiconductor ICs and the like.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view showing an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a conventional example. In the figure, l is a microwave waveguide, 2 is a gas conduit, and 3 is a microwave waveguide.
4 indicates a partition wall, 4 indicates a plasma processing chamber, 5 indicates a gas beam, and 6 indicates an opening. Tai 1st v-2 Showa 1r Ia 0 hook Related Patent Applicant Address: 1015-8 Koguchi J-Naka, Nakaku-ku, Yosaki City, Kanagawa Prefecture (522) Name: Fujitsu Limited 4, Agent Address: 1015-8, Kami Elementary School, 81 Nakahara Ward, Yosakiyama, Kanagawa Prefecture, Contents of Amendment Attachment (1) "Figure 2 (a)" on page 6, line 16 of the specification
2(b)".

Claims (1)

[Claims] A plasma processing apparatus that generates plasma by blowing out a reactive gas in a beam shape in a direction parallel to the direction of propagation of microwaves in a waveguide that propagates microwaves.