JPH0640542B2 - Microwave plasma processing equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus which can be used for etching, vapor phase growth method and the like in the semiconductor industry.

2. Description of the Related Art In recent years, microwave plasma processing apparatuses have been applied to etching and vapor phase growth.

An example of the microwave plasma processing apparatus described above will be described below with reference to the drawings.

FIG. 4 shows a sectional view of a conventional microwave plasma processing apparatus.

The vacuum chamber 1 has a gas inlet 2 and a microwave inlet 3, and a magnet coil 4 for obtaining a uniform magnetic field in the axial direction is installed around the vacuum chamber 1. Reference numeral 5 is a waveguide for introducing microwaves, and 6 is a quartz glass plate for keeping the vacuum chamber 1 in vacuum by using an O-ring and for introducing microwaves. Reference numeral 7 is a sample table on which the processing substrate 8 is placed, and 9 is a vacuum exhaust port.

The operation of the microwave plasma processing apparatus configured as described above will be described below in the case of etching polysilicon.

The vacuum chamber 1 has about 1 when the gas is supplied from the gas inlet 2.
Maintained at 0 ^-4 Torr.

S as an etching gas introduced from the gas inlet 2
The F ₆ gas is a magnetic field in the axial direction (875) generated by the microwave introduced from the microwave introduction port 3 and the magnet coil 4.
Gauss) discharges when electron cyclotron resonance is satisfied. The electrons, ions and radicals generated by this plasma discharge reach the processing substrate 8 on the sample stage 7 by the action and diffusion of the magnetic field and etch the polysilicon.

Problems to be Solved by the Invention However, in the above-mentioned configuration, since ions and radicals diverge from the central portion toward the outside, the amount of ions and radicals reaching the processed substrate increases as the center increases and the distance toward the outside increases. Less. In the case of actual etching, the etching rate in the center was higher than that in the outside, and there was a problem that the uniformity was poor.

In view of the above problems, the present invention provides a microwave plasma processing apparatus that improves processing uniformity of a processing substrate.

Means for Solving the Problems In order to solve the above problems, a microwave plasma processing apparatus of the present invention is a vacuum chamber having a gas inlet and a microwave inlet, and a magnetic field that is uniform in the axial direction in the vacuum chamber. And a sample table on which a substrate to be surface-treated is placed in the vacuum chamber, and only the outer peripheral portion of the substrate is provided on the surface of the sample table opposite to the surface on which the substrate is placed. It is provided with a structure in which a plate of a high magnetic permeability material or a permanent magnet is provided at a position facing each other.

Action According to the present invention, the plasma generated by the microwave and the magnetic field is transported in the magnetic field direction by the configuration described above. The electrons and ions that have reached the vicinity of the substrate are further magnetized by the magnet coil into a ring-shaped high-permeability material or permanent magnet, and the magnetic field of the magnet coil is directed toward the ring-shaped high-permeability material or permanent magnet near the substrate. As a result, the amount of ions concentrated and incident on the surface of the substrate will increase on the outside as compared with the case where there is no high-permeability material or permanent magnet, and the uniformity is improved over the entire surface of the substrate.

Embodiment A microwave plasma processing apparatus according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a microwave plasma processing apparatus according to the first embodiment of the present invention. In FIG. 1, the vacuum chamber 9
Has a gas inlet 10 and a microwave inlet 11, and a magnet coil 12 for obtaining a uniform magnetic field in the axial direction is installed around the vacuum chamber 9. Reference numeral 13 is a waveguide for introducing a microwave, and 14 is a quartz glass plate for maintaining a vacuum in the vacuum chamber 9 via an O-ring and for introducing a microwave. 15 is the processing substrate 1
Non-magnetic material for mounting 6 (eg SUS331)
It is a sample stand consisting of. Reference numeral 17 is a ring-shaped plate made of a high magnetic permeability material (for example, SUS440A).
18 is a vacuum exhaust port. FIG. 2 is a diagram showing the direction of the magnetic field near the processing substrate 16.

With regard to the microwave plasma processing apparatus configured as described above, the case of etching polysilicon will be described below with reference to FIGS. 1 and 2. The vacuum chamber 9 is maintained at a vacuum of about 6 × 10 ⁻⁴ Torr with 5 SCCM of SF ₆ gas flowing from the gas inlet 10. Gas inlet 1
The gas introduced from 0 is discharged when the electron cyclotron resonance is satisfied by the microwave introduced from the microwave introduction port 11 and the axial magnetic field (875 Gauss) by the magnet coil 12. The electrons, ions and radicals generated by this plasma discharge move toward the processing substrate 16 by the action or diffusion of the magnetic field. Also, the electrons and ions that have moved toward the processing substrate 16 are
As shown in the figure, depending on the direction of the magnetic field, the processing substrate 16 is etched so as to be concentrated in the outer peripheral direction of the processing substrate 16.

As described above, according to this embodiment, below the sample table 15,
By providing the ring-shaped plate 17 made of a high-permeability material, the ions are concentrated in the outer peripheral direction of the processing substrate 16, and the uniformity is improved and the outer diameter is 5 inches as compared with the case where the ring-shaped plate 17 is not provided. Variation of ± 8% with respect to the processing substrate 16 of
To ± 6%.

A second embodiment of the present invention will be described below with reference to the drawings. The difference from the configuration of FIG. 1 is that instead of the ring-shaped plate 17 having high magnetic permeability, a ring-shaped permanent magnet 19 having an S pole on the upper side is provided.
It is exactly the same as the figure. FIG. 3 is a diagram showing the direction of the magnetic field near the processing substrate 16. Explaining this case, as in the case of FIG. 1, when the electron cyclotron resonance is satisfied by the magnet coil 12 and the microwave, the gas introduced from the gas inlet 10 is discharged.
The electrons, ions and radicals generated by this plasma discharge move toward the processing substrate 16 by the action or diffusion of the magnetic field. The electrons and ions that have moved toward the processing substrate 16 etch the processing substrate 16 as if they were concentrated in the outer peripheral direction of the processing substrate 16 depending on the direction of the magnetic field as shown in FIG.

As described above, when the ring-shaped permanent magnet 19 having the south pole on the upper side is provided below the sample table 15, ions are concentrated in the outer peripheral direction of the processing substrate 16, and the ring-shaped permanent magnet 19 is not provided. Compared to, the uniformity is improved, and the variation is ± 8% to ± for the processing substrate 16 having an outer diameter of 5 inches.
It improved to 5%.

In addition, in the first embodiment, the ring-shaped plate 17 is
Although S440A is used, a high magnetic permeability material may be used.

In addition, in the second embodiment, the ring-shaped permanent magnet 19
Is the S pole above, but this is the case when the direction of the magnetic field of the magnet coil 12 is toward the permanent magnet 19,
In the opposite case, the upper side should be the N pole.

Further, although the case of the etching apparatus has been described in the present embodiment, it can be similarly applied to a vapor phase growth (CVD) apparatus.

As described above, according to the present invention, a plate of a ring-shaped high magnetic permeability material having a size equal to or larger than the outer diameter of the substrate is formed on the side opposite to the surface of the sample table on which the substrate is mounted, or By providing the permanent magnet below the sample table, the uniformity of the amount of ions incident on the substrate can be improved, and as a result, the processing uniformity of the substrate can be improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a microwave plasma processing apparatus according to the first embodiment of the present invention, FIG. 2 is a diagram showing the direction of a magnetic field near the processing substrate of FIG. 1, and FIG. 3 is a second embodiment. FIG. 4 is a diagram showing the direction of the magnetic field near the processing substrate in FIG. 4, and FIG. 4 is a diagram of a conventional microwave plasma processing apparatus. 9 ... Vacuum chamber, 10 ... Gas inlet, 11 ... Microwave inlet, 12 ... Magnet coil (magnetic field applying means), 16 ... Processing substrate, 17 ... Ring-shaped plate made of high-permeability material , 19 ... Ring-shaped permanent magnet.

Claims (1)

[Claims] 1. A sample in which a vacuum chamber having a gas inlet and a microwave inlet, magnetic field applying means for applying a uniform magnetic field in the axial direction in the vacuum chamber, and a substrate to be surface-treated in the vacuum chamber are mounted. And a table, and a plate of a high magnetic permeability material or a permanent magnet is provided at a position facing only the outer peripheral portion of the substrate on the surface of the sample table opposite to the surface on which the substrate is mounted. Wave plasma processing equipment.