JPH0732134B2 - Plasma equipment - Google Patents

Description

TECHNICAL FIELD The present invention relates to a plasma apparatus used as a CVD (Chemical Vapor Deposition) apparatus, an etching apparatus, a sputtering apparatus, or the like.

[Prior art]

Since the plasma device using electron cyclotron resonance can generate highly active plasma at low gas pressure and can draw out a large-diameter plasma flow, its research is applicable to thin film formation and etching in highly integrated semiconductor devices etc. ， Development is in progress.

FIG. 4 is a vertical cross-sectional view showing a conventional plasma apparatus configured as a thin film forming apparatus, and 31 in the figure shows a plasma generation chamber. The plasma generation chamber 31 is provided with a microwave introduction port 31c sealed with a quartz glass plate 31b at the center of the upper wall, and a plasma extraction window 31d at a position facing the microwave introduction port 31c at the center of the lower wall. One end of a waveguide 32 whose other end is connected to a high-frequency oscillator (not shown) is connected to the microwave introduction port 31c, and a reaction chamber 33 is disposed so as to face the plasma extraction window 31d, and plasma is further generated in the surroundings. An exciting coil 34 is arranged concentrically with the chamber 31 and one end of the waveguide 32 connected thereto so as to surround them.

A disk-shaped mounting table 37 is provided in the reaction chamber 33, and a sample S such as a disk-shaped wafer is mounted on the mounting table 37 as it is or detachably by means such as electrostatic adsorption. Further reaction chamber 33
An exhaust port 33a connected to an exhaust device (not shown) is opened in the lower wall of the. 31g and 33g are raw material gas supply pipes.

Thus, in such a thin film forming apparatus, the source gas is supplied into the plasma generation chamber 31 and the reaction chamber 33 which are set to a required degree of vacuum, and the excitation coil 34 forms a magnetic field while the plasma generation chamber is formed. Plasma is generated by introducing microwave into the plasma 31, and the generated plasma is generated by a divergent magnetic field whose magnetic flux density decreases toward the reaction chamber 33 side in front of the plasma extraction window 31d formed by the excitation coil 34. It is led out from the chamber 31 through the plasma extraction window 31d to the periphery of the sample S on the mounting table 37 in the reaction chamber 33, and a surface reaction is caused by the ions and radical particles in the plasma flow on the sample S surface to form a film on the sample S surface. (Japanese Patent Laid-Open No. 56-155535).

[Problems to be solved by the invention]

By the way, in the conventional plasma apparatus as described above, the plasma generated in the plasma generation chamber 31 passes through the plasma extraction window 31d along the magnetic field lines of the divergent magnetic field formed by the exciting coil 34 and passes through the sample S in the reaction chamber 33. Pulled out to the side.

The plasma is not uniformly generated in the plasma generation chamber 31, but is generated so that the plasma density becomes higher in the central portion of the plasma generation chamber 31, so that the unevenness in the plasma generation chamber 31 remains unchanged due to the divergent magnetic field. A phenomenon that the image is enlarged and projected toward the sample S is recognized. Therefore, the plasma density distribution of the plasma extracted from the divergent magnetic field is high in the central portion of the sample S and low in the peripheral portion, which causes a difference in the deposition rate in the sample S, and the nonuniformity of the film thickness cannot be avoided. was there.

Such non-uniformity of the film thickness or the etching depth varies not only in the thin film forming apparatus but also in the case where the film is used as an etching apparatus or a sputtered thin film forming apparatus (Japanese Patent Laid-Open No. 59-47728). The phenomenon is acknowledged.

The present invention has been made in view of such circumstances, the object is to make the magnetic flux density distribution on the surface uniform,
It is another object of the present invention to provide a plasma device having a uniform plasma density and capable of performing uniform film formation or uniform etching.

[Means for solving problems]

The plasma device according to the present invention is a plasma device in which plasma is generated using electron cyclotron resonance, and this is led out from a plasma extraction window to a sample chamber provided with a sample mounting table by using a magnetic field. A magnetic field generator for generating a magnetic field having a higher magnetic flux density in the peripheral portion of the sample than that in the central portion is arranged on the opposite side of the plasma drawing window with respect to the sample on the mounting table, and the magnetic field generator generates plasma on the sample surface. In order to make the density uniform, it is composed of a cylindrical magnetic body having an outer diameter substantially equal to or larger than the diameter of the sample, and a coil arranged concentrically around the magnetic body. Characterize.

[Action]

The present invention uses a magnetic field generator composed of a cylindrical magnetic body and a coil arranged concentrically around the magnetic body, so that the magnetic flux density at the peripheral portion of the sample is relatively high relative to the central portion, and With respect to the plasma drawn out, the portion having a low density in the peripheral portion of the plasma generation chamber 31 has a high density on the surface of the sample S, and conversely, the portion having a high density in the central portion of the plasma generation chamber 31 has the sample S. The density becomes low on the surface, and as a result, the plasma density distribution is made uniform on the surface of the sample S. Therefore, the processing speed such as the film forming speed and the etching speed, which have been non-uniform in the past, is made uniform.

〔Example〕

An embodiment in which the present invention is configured as a thin film forming apparatus will be specifically described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of a plasma device according to the present invention (hereinafter referred to as the device of the present invention), in which 1 is a plasma generation chamber, 2 is a waveguide, and 3 is a sample S.
On the other hand, a reaction chamber 4 which is a sample chamber for film formation shows an exciting coil.

The plasma generation chamber 1 has a microwave introduction port 1c closed by a quartz glass plate 1b at the center of the upper wall, and a circular plasma extraction window 1d at a position facing the microwave introduction port 1c at the center of the lower wall. One end of the waveguide 2 is connected to the microwave introduction port 1c, and the plasma extraction window 1d
A reaction chamber 3 is disposed so as to face this, and an exciting coil 4 is provided around the plasma generating chamber 1 and one end of a waveguide 2 connected to the plasma generating chamber 1.

The other end of the waveguide 2 is connected to a high-frequency oscillator (not shown) so that the emitted microwave is introduced into the plasma generation chamber 1 through the microwave introduction port 1c. The exciting coil 4 is connected to a DC power source (not shown), forms a magnetic field so that plasma can be generated by introducing microwaves into the plasma generation chamber 1 by flowing a DC current, and the excitation coil 4 is directed toward the reaction chamber 3 side. A divergent magnetic field that lowers the magnetic flux density is formed so that the plasma generated in the plasma generation chamber 1 can be led out to the reaction chamber 3.

At the center of the lower part of the reaction chamber 3, there is a plasma extraction window.
A mounting table 7 is arranged at a position facing 1d, and a sample S such as a disk-shaped wafer is mounted on the mounting table 7 as it is or detachably by means such as electrostatic adsorption. Yes,
Further, the bottom wall is provided with an exhaust port 3a which communicates with an exhaust device (not shown). 1g and 3g are raw material gas supply pipes.

In the apparatus of the present invention, the cylindrical magnetic body 5 is disposed below the mounting table 7 substantially concentrically with the plasma extraction window 1d, the mounting table 7 and the sample S mounted thereon. Has been done. The outer diameter D of the magnetic body 5 is set to be substantially equal to or larger than the diameter of the sample S, and the inner diameter d is set to a value other than zero, that is, 0 <d <D.

FIG. 2 is an explanatory diagram showing a state of magnetic force lines when the disk-shaped sample S and the cylindrical magnetic body 5 having the outer diameter D as described above are used, and the divergent magnetic field formed by the exciting coil 4 is shown. The magnetic lines of force are attracted to the magnetic body 5. That is, the magnetic field lines spreading outside the magnetic body 5 are pulled back inward, and the magnetic field lines inside the magnetic body 5 are pushed outward, so that the density distribution of the plasma drawn from the plasma generation chamber 31 on the surface of the sample S is Is equalized corresponding to.

This will be described in more detail below.

What is important in the present invention is that it is important to use a magnetic field generator that generates a magnetic field having a higher magnetic flux density in the peripheral portion of the sample than in the central portion, that is, the cylindrical magnetic body 5 in the above embodiment.

For example, Japanese Examined Patent Publication No. 58-13627 describes an etching device for generating a plasma by a microwave as in the present invention, and a magnet is provided on the opposite side of a coil for generating the magnetic field or a plasma extraction window from the sample. It is provided to form a mirror magnetic field. FIG. 6 is a schematic diagram showing a state of magnetic force lines when a mirror magnetic field is formed. In the figure, 61 is a coil that forms a divergent magnetic field, and 62 is a magnet that forms a mirror magnetic field. In such a mirror magnetic field, although the magnetic flux generated by the coil 61 converges without diverging due to the presence of the magnet 62, the magnetic flux density is high in the central part and remains low in the peripheral part, and the sample is placed in this magnetic field. However, even if the plasma can be used without waste, it is not possible to make the plasma density uniform on the sample surface.

FIG. 7 shows the relationship between the distance r (cm) from the center of the sample (see FIG. 6) and the magnetic flux density Bz distribution, which is a component in the direction perpendicular to the mounting table on the mounting table 7, showing the divergent magnetic field (broken line) and the mirror magnetic field. (One-dot diagonal line) and the magnetic field (solid line) by the magnetic field generator of the present invention are described. As is clear from this figure, in the apparatus of the present invention, by making the peripheral portion of the sample higher than the central portion, the plasma density distribution (the peripheral portion is low) in the plasma generating chamber is projected as it is in the divergent magnetic field or the mirror magnetic field. Can be corrected.

FIG. 3 is a schematic cross-sectional view showing another configuration of the magnetic body used in the device of the present invention, in which a thin insulating coated conductive wire 6 is closely packed many times on the outer peripheral surface of the cylindrical magnetic body 5. It is wound around, and a DC power supply (not shown) is connected between its ends so that a DC current of a required magnitude can be passed to finely adjust the magnetic flux density distribution on the surface of the sample S.

The electrically conductive wire 6 coated with insulation may be arranged in a ring shape around the magnetic body 5 instead of being wound directly on the outer peripheral surface of the magnetic body 5. The other structure is substantially the same as that of the magnetic body shown in FIGS.

Further, in each of the above-described embodiments, the magnetic body 5 is arranged below the mounting table 7, but the magnetic body 5 may be arranged on the mounting table 7 at any position below the sample S. Alternatively, the magnetic body 5 and the mounting table 7 may be integrally formed, or the magnetic body 5 may also serve as the mounting table 7.

Regarding the apparatus of the present invention as described above and the conventional apparatus shown in FIG. 4, O ₂ gas was supplied to the plasma generation chamber 1 and to the reaction chamber 3 respectively.
SiH ₄ gas was introduced as a source gas to generate plasma, which was deposited on a Si wafer having a diameter of 5 inches on the mounting table 7, and the variation in the film thickness distribution was measured. %, But ± 5 with the device of the present invention
Could be reduced to%.

The film thickness distribution was calculated by the following formula.

[Effects] As described above, in the device of the present invention, the sample is formed toward the sample chamber side by the cylindrical magnetic body on the side opposite to the plasma drawing window and the coil concentrically arranged around the magnetic body. Among the magnetic field lines of the divergent magnetic field, the magnetic field lines in the peripheral portion of the sample or in the vicinity thereof are curved in a direction intersecting the sample peripheral portion, that is, inward and outward directions, and the magnetic flux density in the peripheral portion of the sample is increased,
The present invention has excellent effects such that the magnetic flux density distribution on the surface of the sample is improved and the film can be formed into a film having a uniform thickness.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical cross-sectional view of the device of the present invention, FIG. 2 is an explanatory view showing lines of magnetic force in the device of the present invention, and FIG. 3 shows another structure of a magnetic body used in the device of the present invention. FIG. 4 is an enlarged cross-sectional view, FIG. 4 is a vertical cross-sectional view of a conventional apparatus, FIG. 5 is an explanatory view showing a relationship between a magnetic field line of a diverging magnetic field for plasma extraction in the conventional apparatus and a sample, FIG. 6 is an explanatory view of a mirror magnetic field, FIG. 7 is a magnetic flux density distribution diagram in various magnetic fields. 1 ... Plasma generation chamber, 2 ... Waveguide, 3 ... Reaction chamber,
4 ... Excitation coil, 5 ... Magnetic material, 6 ... Conductive wire, 7 ...
… Mounting table, S… Sample

Claims (1)

[Claims] 1. A plasma apparatus in which plasma is generated by utilizing electron cyclotron resonance, and the plasma is led out from a plasma extraction window to a sample chamber provided with a sample table by using a magnetic field. A magnetic field generator for generating a magnetic field having a higher magnetic flux density in the peripheral portion of the sample than that in the central portion is arranged on the side opposite to the plasma extraction window with respect to the sample, and the magnetic field generator controls the plasma density on the sample surface. In order to make it uniform, it is composed of a cylindrical magnetic body having an outer diameter substantially equal to or larger than the diameter of the sample, and a coil concentrically arranged around the magnetic body. Plasma device.