JPH02205020A - Microwave plasma treatment equipment - Google Patents

Abstract

PURPOSE:To treat a sample uniformly with plasma at high speed by disposing magnetic field shielding plates onto the upper and lower surfaces of the outsides of two ring-shaped coils and increasing magnetic field intensity working to a plasma generating region while rationalizing a coil current value for generating a magnetic field. CONSTITUTION:Magnetic field shielding plates 46, 47 for preventing divergence to the outside of a magnetic field generated by ring-shaped coils 50 are inserted to the upper and lower surfaces of the two ring-shaped coils 50. The opening diameters of the magnetic field shielding plates 46, 47 are brought to approximately the same as those of a microwave waveguide 60 and a discharge tube 30, thus making the passage areas of the magnetic lines of force on the top faces and undersides of the ring-shaped coils smaller than conventional devices, then effectively increasing magnetic field intensity on a coil central axis working to a plasma generating region. Accordingly, plasma having a density higher than those of conventional devices can be acquired while the uniformity of plasma is obtained by properly setting the current values of the two ring-shaped coils.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave plasma processing apparatus, and particularly to a magnetic field type microwave plasma processing apparatus.

[Conventional technology]

An apparatus for etching a sample such as a semiconductor element substrate as a conventional microwave plasma processing apparatus 547 will be explained with reference to FIG.

In FIG. 4, a vacuum evacuation device 10 is connected to a vacuum vessel having an open end on the upper side, and a discharge tube I having an open end on one side.
In this case, the structure is airtight in the vertical direction. Discharge tube (
A waveguide tube is installed on the outside of the tube, including between the discharge tubes.
On the outside of the equal-wave tube, magnetic field generating means, for example, a coil-shaped coil, is installed in two stages in the horizontal direction. Further, a magnetic field shield plate 6 is arranged around the outer periphery of the annular coil.

The waveguide is connected to the microwave generation means 70 via a microwave waveguide.

A nozzle 21 for introducing discharge gas is provided in the vacuum container, and a discharge gas supply device is connected to the nozzle 4 via a gas conduit. It is connected to the sword. A sample electrode 110 is provided in a space 100 formed by the vacuum container (9) and the discharge tube. A high frequency power source 120 is connected to the sample electrode 110, and a ground electrode 130 is provided on the grounded vacuum vessel.

A sample 140 is attached to the sample electrode 110 using a sample holder 1 made of an insulating material.
50, and the space 100 is equipped with a vacuum exhaust system [1
0, the pressure is reduced to a predetermined pressure. then space 10
0 is a gas conduit (material) from the discharge gas supply device f9fJ,
The discharge gas is introduced at a predetermined temperature through the nozzle 21, and the pressure in the space 100 is appropriately adjusted to a predetermined processing pressure by the evacuation device 10.

On the other hand, an electric field due to microwaves generated by the microwave generator 70 and a magnetic field generated by the ring-shaped coil are applied to the space 100, and the discharge gas present in the discharge area in the discharge tube is turned into plasma, and the sample High frequency power is applied to the electrode 110 from a high frequency power supply 120, thereby generating a high frequency bias.

The sample 140 is etched with high precision by controlling the ion energy by appropriately adjusting the high frequency power.

The M alloy film is etched using a chlorine-based gas using the microwave plasma etching apparatus described above, and the underlying film, for example, the 8i02 film, is etched when performing so-called over-etching for the purpose of removing the remaining M film. An example is shown in the fifth factor.

The values in Figure 5 indicate the etching rate of the 5i02 film per minute, and the average etching rate is 8211.
Although an etching uniformity of approximately ±12% was obtained, there was considerable variation in the etching speed. Furthermore, in areas where the etching rate was low, a large amount of etching residue was observed during etching of the M alloy film. Etching residue and non-uniform etching of the underlying film cause variations in electrical properties and defects in LSI devices, which pose problems in device manufacturing.

Note that related devices of this type include, for example,
JP-A-60-103618, JP-A-60-15462
No. 0, JP-A-60-158629, and the like.

[Problem to be solved by the invention]

In the above conventional technology, no consideration is given to improving the magnetic field shield plate to achieve a high magnetic field and making the plasma even more dense and uniform. I have a problem with this.

An object of the present invention is to provide a microwave plasma processing apparatus capable of processing a sample at high speed and with good uniformity.

[Means to solve the problem]

The above purpose is to create a high-density, uniform plasma by installing magnetic field shield plates on the top and bottom surfaces of the two annular coils to increase the magnetic field strength that acts on the plasma generation area, and to increase the coil current value for generating the magnetic field. This can be achieved by providing a means for making it appropriate.

[For production]

The present invention is achieved by appropriately arranging magnetic field shield plates on the upper and lower surfaces of the outside of two sets of annular coils and appropriately controlling the annular coil current value in order to obtain high-density and uniform plasma.

High-density plasma is created by inserting a magnetic field shield plate to replace the magnetic field that was conventionally emitted from the top and bottom surfaces of the coil, making the area through which the lines of magnetic force pass approximately the same as the diameter of the microwave waveguide and discharge tube, increasing the magnetic flux density. This is achieved by dynamically increasing the magnetic field strength acting on the plasma generation region.

On the other hand, uniform plasma can be achieved by appropriately setting the current values of the two annular coils.

〔Example〕

An embodiment of the present invention will be explained with reference to FIGS. 1, 2, and 3. It should be noted that the processing operations for samples such as semiconductor element substrates in the microwave plasma etching apparatus of this embodiment are the same as those in the prior art, and therefore the explanation thereof will be omitted. Further, the same members in the apparatus configuration of FIG. 1 as those of the conventional apparatus shown in FIG. 4 are designated by the same reference numerals, and the explanation thereof will be omitted.

In FIG. 1, magnetic field shield plates 46 and 47 are inserted on the upper and lower surfaces of the two annular coils to prevent the magnetic field generated by the annular fill from dispersing to the outside. Magnetic field shield plate 4
By making the aperture diameter of 6.47 approximately the same as the aperture diameter of the microwave waveguide ω and the discharge tube, the area through which the lines of magnetic force pass on the top and bottom surfaces of the annular coil can be made smaller than before, effectively allowing the plasma generation region to The magnetic field strength on the acting coil central axis can be increased.

Figure 2 shows the current value of the circular coil father at the upper coil 25A.

The magnetic field strength distribution a in the vertical direction on the coil center axis when the lower coil 15A is used is shown together with the distribution in the conventional example. According to the present invention, since a higher magnetic field strength can be obtained in the plasma generation region than in the past, higher density plasma can be obtained than in the past. On the other hand, plasma uniformity can be obtained by appropriately setting the current values of the two annular coils.

In Figure 3'! The etching rate distribution of the underlying 5i02 film is shown when the M alloy film is etched using the apparatus configured as shown in Figure J1, and then M overetching is performed for the purpose of removing the remaining M film. As a result, an average etching rate of 901 ul/mln and an etching uniformity of about ±6 were obtained, and the etching uniformity of the base film was much improved compared to the conventional method.

In addition, by forming a high-density and uniform plasma, the amount of ions in the plasma increases, and the etching residue caused by the Cu component in the M alloy film, which has often occurred and caused problems in the past, is a problem in terms of the electrical characteristics of the device. We were able to sufficiently reduce this to a level of zero.

Note that since the etching rate of the underlying film increases, the etching rate ratio with respect to the M alloy film, the so-called selectivity (1'-1t
/8 i 02 ), but as the plasma density increased, the number of radical species increased and the etching rate of the M alloy film also increased, so a value equivalent to the conventional value was obtained.

According to this embodiment, since the M alloy film can be etched evenly with no residue, a product with stable electrical characteristics of an LSI element can be obtained, and an etching apparatus with a high product yield can be obtained.

Although this embodiment shows the case where the present invention is applied to etching an M alloy film, it goes without saying that the present invention can be applied to various types of etching by changing the material to be etched and the etching conditions.

Further, for example, even when a sample is subjected to a film forming process such as a plasma CVD process, the present invention can be effectively applied if the processing apparatus is a magnetic field type microwave plasma processing apparatus.

〔Effect of the invention〕

According to the present invention, since high-density and uniform plasma can be obtained, there is an effect that a sample can be plasma-treated at high speed and with good uniformity.

[Brief explanation of the drawing]

Figure 1 shows an example of microwave plasma etching according to the present invention! 582 is a magnetic field distribution diagram showing a comparison of the effect when using the apparatus shown in Fig. 1 and the conventional example, and Fig. 3 is the etching rate of 8i02 film using the apparatus shown in Fig. 9161. Distribution diagram, Figure @4 is a vertical cross-sectional view of a conventional microwave plasma etching apparatus, and FIG. 5 is an etching rate distribution diagram when etching 8i02 using the conventional apparatus.

Claims (1)

[Claims] 1. A microwave electric field is applied by a microwave generator, and a discharge gas is introduced into a discharge region to which an external magnetic field is applied to generate a microwave discharge, and the emitted plasma is used to generate a sample. A microwave plasma processing apparatus for surface processing, characterized in that the means for generating the external magnetic field is provided with a magnetic field shield plate made of a magnetic material. 2. Providing a magnetic field shield plate on the external magnetic field generating means,
The microwave plasma processing apparatus according to claim 1, wherein the opening area of the lower magnetic field shielding plate is larger than that of the upper magnetic field shielding plate. 3. The microwave plasma processing apparatus according to claim 2, wherein the opening diameter of the upper magnetic field shield plate is approximately equal to the microwave waveguide diameter, and the opening diameter of the lower magnetic field shield plate is approximately equal to the discharge tube diameter.