JP2515885B2 - Plasma processing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a plasma processing apparatus, and particularly to etching of a sample such as a semiconductor element substrate using plasma generated by the action of a microwave electric field and a magnetic field. The present invention relates to a plasma processing apparatus for performing.

[Conventional technology]

As a technique for processing a sample such as a semiconductor element substrate using at least plasma generated by the action of a microwave electric field, for example, a technique described in Japanese Patent Publication No. 58-13627 is known.

[Problems to be Solved by the Invention] For example, in the etching treatment of an insulator such as a silicon oxide film, the contribution of ions that are high-energy particles is larger than that of active neutral particles such as radicals in plasma. However, if the ion energy is too high, the sample is ion-damaged, which is not preferable. Therefore, the plasma is preferably energy enough to ionize the processing gas, and in order to improve the processing speed, it is necessary to improve the ionization rate, that is, the plasma density. Further, if the plasma density is not uniform on the surface to be processed of the sample, the uniformity of processing of the sample cannot be ensured.

In the above-mentioned prior art, no consideration is given to making the ion species in the plasma uniform on the surface to be processed of the sample, and there is a problem in ensuring the uniformity of processing of the sample.

An object of the present invention is to provide a plasma processing apparatus which ensures processing uniformity of a sample processed by using plasma generated by the action of a microwave electric field and a magnetic field and has a high processing speed.

[Means for solving the problem]

The above-mentioned object is to use a plasma processing apparatus to process a sample by using a plasma generating part in which plasma is generated by a synergistic effect of a microwave electric field and a magnetic field, and a plasma which is disposed in the vicinity of the plasma generating part and which is generated. And a means for shielding the magnetic field applied to the plasma processing section.

[Action]

In the plasma generation part, plasma is generated by the synergistic action of the microwave electric field and the magnetic field. The plasma is
The sample enters the plasma processing unit disposed in the vicinity of the plasma generating unit, and the sample is subjected to an etching process, a film forming process, or the like using the plasma. In this case, the magnetic field to the plasma processing unit is shielded by the magnetic field shield means. That is, since the magnetic field is applied to the plasma in the plasma generation unit, the charged particles in the plasma make a rotational motion around the magnetic lines of force and the plasma moves along the magnetic gradient. On the other hand, since the magnetic field is not applied to the plasma processing unit by the magnetic field shielding means, the charged particles in the plasma of the plasma processing unit are freely diffused, whereby the plasma processing unit is filled with uniform plasma.

〔Example〕

 Hereinafter, an embodiment of the present invention will be described with reference to FIG.

The means for forming the discharge space 70 in FIG. 1 is the discharge tube 10 in this case. In this case, the discharge tube 10 has a hemispherical closed end at one end and an open end with a circular opening at the other end, and is formed of an insulator such as quartz.

Microwaves from the magnetron 20 which is microwave oscillating means are propagated to the discharge tube 10 via the waveguides 30 and 31 which are microwave propagating means. In this case, air core coils 40 and 41 as magnetic field applying means are provided in two stages on the outer circumference of the discharge tube 10. The sample holding means is a sample table 50 having a sample mounting surface on its surface, and is arranged below the discharge tube 10 so that the sample can be horizontally mounted.

In FIG. 1, the container 60 has an open top wall,
It is fitted to the open end of the discharge tube 10.

The sample table 50 is provided on the bottom wall of the container 60, and the sample table shaft 51 is airtightly insulated from the container 60 (not shown) and protrudes out of the container 60. ,
A high frequency power supply 80 is connected.

A vacuum exhaust device 100 is connected to the container 60 via an exhaust pipe 101. Here, the sample space 90 refers to the space between the sample table 50 surrounded by the container 60 and the lower end of the discharge tube 10. A processing gas is supplied to the upper portion of the sample space 90 from the outside of the container 60 via a processing gas introduction device (not shown) and a processing gas introduction pipe 110.

The upper air-core coil 40 and the lower air-core coil 41, which are magnetic field applying means, are located at positions substantially corresponding to the discharge tube 10, and by the magnetic shields 120 to 122 such as pure iron that are magnetic field shielding means,
The upper surface of the upper coil 40, the lower surface of the lower coil 41, and the outer peripheral surfaces of the upper coil 40 and the lower coil 41 are shielded, and the magnetic field strength is considered to weaken from the spherical top of the discharge tube 10 toward the open end. Is set so that an electron cyclotron resonance condition exists in the discharge tube, and in particular, the magnetic field is not applied to the sample space 90 by the magnetic shield 122 on the lower surface of the lower coil 41.

Next, the operation will be described. In FIG. 1, the discharge space 70
The sample space 90 is decompressed and evacuated by the vacuum evacuation device 100, and a predetermined process gas, for example, an etching gas is introduced from the process gas supply device at a predetermined flow rate. A part of the gas introduced into the discharge space 70 and the sample space 90 is a vacuum exhaust device.
It is evacuated by 100, so that the pressure of the spaces 70, 90 is adjusted to a predetermined etching pressure. On the other hand, the sample 130 is installed on the sample installation surface of the sample table 50 with the surface to be processed facing upward. The microwave oscillated by the magnetron 20 is propagated to the discharge tube 10 by the waveguides 31 and 30, and the air-core coils 40 and 41.
The etching gas in the discharge tube 10 is turned into plasma due to the interaction with the magnetic field generated by. Due to the strong magnetic field action in the discharge space 70, the generated charged particles in the plasma are suppressed from diffusing in the direction perpendicular to the magnetic field, and diffuse to the open end side of the discharge tube 10 where the magnetic field is weak. The plasma generated in the discharge space 70 has a non-uniform density close to the electric field mode distribution of the microwave determined by the dimensions of the waveguide 30. For the above reason, the non-uniform density plasma causes the open end of the discharge tube 10. To the sample space 90. On the other hand, since the magnetic field does not exist in the sample space 90 due to the magnetic shield 122, the plasma emitted to the sample space 90 rapidly diffuses in the sample space 90, and the uniformed plasma is placed on the sample table 50. The processed surface of the sample 130 thus formed is covered, and the processed surface of the sample 130 is uniformly etched by the plasma. At this time, by applying a high-frequency bias voltage from the high-frequency power source 80 to the sample stage 50, the ion species in the plasma are attracted to the sample 130 at a negative cycle of the high-frequency bias and made incident on the processing surface thereof, and are uniformly Ion etching can be performed. Further, since the discharge space and the processing space are different, it is possible to generate plasma having different discharge energy in the discharge space, that is, plasma in which ion species and radical species are changed, without affecting the treatment space.

In the above-described one embodiment, the etching apparatus has been described as an example of the plasma processing apparatus, but the invention can be similarly applied to, for example, a CVD apparatus.

FIG. 2 shows a second embodiment of the present invention. The difference from FIG. 1 showing the above-mentioned one embodiment is that the container 60 'is formed of a magnetic shield material. That is, in this case, the magnetic shields 120 to 122 in FIG. 1 are unnecessary. Note that, in FIG. 2, the same devices and parts as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted.

In the present embodiment, the same operation as that of the above-described one embodiment occurs, and the same effect can be obtained.

FIG. 3 shows a third embodiment of the present invention. The point shown in FIG.
0 is that a porous cylinder 123 made of a magnetic shielding material is arranged. Note that, in FIG. 3, the same devices and parts as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted.

Also in this embodiment, the same operation and effect as those of the above-described one embodiment can be obtained. It should be noted that a mesh cylinder or the like may be used instead of the perforated cylinder in the present embodiment, and the cylinder is not necessarily required.

〔The invention's effect〕

According to the present invention, since high-density plasma can be generated by the interaction between a magnetic field and microwaves and its density distribution can be made uniform, there is an effect that the processing speed of a sample to be plasma-processed and uniformity can be secured.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a plasma processing apparatus according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a plasma processing apparatus according to a second embodiment of the present invention, and FIG. 3 is a third embodiment of the present invention. FIG. 3 is a configuration diagram of main parts of the plasma processing apparatus of the embodiment. 10 ...... Discharge tube, 20 ...... Magnetron, 30, 31 ...... Waveguide, 40, 41 ...... Air core coil, 50 ...... Sample stage, 60, 60 '......
Container, 80 ... High frequency power supply, 100 ... Vacuum exhaust device, 110 ...
… Processing gas introduction pipe, 120-122 …… Magnetic shield, 123…
… Perforated cylinder

Claims (2)

(57) [Claims] 1. A means for transmitting a microwave, a means for propagating the microwave, a waveguide having a closed wall end to which the means is connected, and a microwave provided in the waveguide for transmitting the microwave. A plasma generating part for generating plasma by the synergistic action of the electric field and magnetic field of the wave; a plasma processing part which is disposed in the vicinity of the plasma generating part and which processes a sample using the generated plasma; A means for shielding the magnetic field to the processing part, a means for decompressing and exhausting a space communicating with the plasma generating part where the plasma processing part is provided, and a means for supplying a processing gas to the decompressed space. Characteristic plasma processing device. 2. The means for shielding the magnetic field comprises a magnetic shield member for the means for generating the magnetic field so that the application region of the magnetic field can be limited to the plasma generating portion. The plasma processing apparatus according to claim.