JP2706022B2 - ECR plasma processing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ECR plasma etching and coating method.

[0002]

2. Description of the Related Art In a conventional ECR plasma processing method, a constant magnetic field of 0.0875 T is applied in parallel with the direction of propagation of a microwave to generate circular motion of electrons, and its angular frequency ω _C and angular frequency of the microwave This is a method in which the entire surface of the sample is processed by electrons using the ECR phenomenon in which ω coincides.

[0003]

In THE INVENTION Problems to be Solved by conventional ECR plasma processing method, since the ion scattering by ECR phenomenon and angular frequency omega _C by circular motion of the angular frequency omega and the electronic microwave match, processed The point was a wide surface, and precise plasma processing of only the target portion could not be performed. Therefore, at the time of partial processing, a mask had to be used. However, as shown in FIG. 4, even when a mask is used, the processed portion of the sample spreads by θ ° due to ion scattering, and the processed bottom surface has a shallow center and a deep undulation at the periphery. In order to focus ions to reduce ion scattering, the mass of the ions is 1758 times larger than the mass of the electrons, and a considerable electromagnetic force is required.

Accordingly, an object of the present invention is to perform processing and coating of an extremely small portion by ECR plasma processing accurately, quickly, and efficiently.

[0005]

SUMMARY OF THE INVENTION The present invention relates to an electron cyclotron resonance (EC) generated by applying a magnetic field in a direction parallel to, or perpendicular to, or perpendicular to and parallel to the traveling direction of microwaves.
R) In an ECR plasma processing method using a phenomenon,
Magnetic field lines is rotated, the rotation diameter rotates the result lines of magnetic force applying becomes smaller like about the pulse voltage to the magnetic field lines rotating coil having funnel according closer to the object to be processed, ions in the plasma This is an ECR plasma processing method characterized by converging along a funnel shape, narrowing an ion flow, and processing the ion beam against a surface of a workpiece. The rotation of the magnetic flux is generated using, for example, a pulse magnetic field generating coil for ion focusing shown in FIG. That is, a plurality of coils 12 are wound around the yoke 11 to form a central portion in a funnel shape, and a pulse current is applied to the yoke 11 so that a rotating magnetic flux (indicated by a dotted line and an arrow in the drawing) is generated between the individual coils 12. generate. By passing the ion current through the center of the rotating magnetic flux, the ion current is focused on the center along the funnel shape. Therefore, it is necessary to change the peak voltage of the pulse width and the pause time by applying the center of this pulse magnetic field generating coil to the sample surface.
In the above, a pulse magnetic field of 1.7 T or more is applied, and the pulse width is set to 0.1.
When a pulse current of 01 to 500 ms is applied to the coil to generate a rotating magnetic flux, the ions are focused and precise processing can be performed.

That is, at the moment of the pulse τ _on, a rotating magnetic flux of several hundred times or more of the DC magnetic field is generated, so that the ions are focused and travel straight along the center thereof, reach the surface of the workpiece, and have a very small portion. Accurately high-speed processing and coating, and reducing the pulse width, increase the ion acceleration and improve the efficiency.

[0007] The present invention is also directed to a structure which is parallel to the traveling direction of microwaves.
Coil that generates a strong magnetic field, or the traveling direction of the microwave
When a pulse voltage is also applied to a coil that generates a magnetic field perpendicular to the magnetic field, a magnetic field exceeding the conventional constant magnetic field is generated, the plasma confinement effect is improved, and a high anisotropy is caused by a decrease in the ion rotation curvature and velocity and a decrease in the ion temperature. Accurate, high-speed, low-damage processing by processing can be performed.

[0008]

An embodiment will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a workpiece, 2 denotes a pulse magnetic field generating coil for ion focusing, and a center portion is formed in a funnel shape. 3 is a coil for generating a pulse magnetic field parallel to the direction in which the microwave travels, 5 is a coil for generating a pulse magnetic field in the ion source perpendicular to the direction in which the microwave travels,
4 is a yoke, 6 is an ion source, 7 is a cooling water drain,
8 indicates the traveling direction of the microwave of 2.45 GHz. 9
Is a reaction gas inlet, and 10 is a cooling water inlet. FIG.
Reference numeral 11 denotes a yoke having a section taken along the line AA ′ in FIG.
Is a coil.

Next, a specific processing example will be described.

For example, when SiO ₂ is used as a workpiece, CF ₄ + 20% H ₂ is flowed as an etching gas,
In order to generate highly ionized plasma in an atmosphere of 5 Torr, a constant magnetic field of 0.0 is applied in a direction parallel to the microwave traveling direction.
A magnetic field of 875T was applied to increase the ion concentration and further reduce the ion concentration. A constant magnetic field of 0.0875T was applied in the vertical direction as a confinement magnetic field for plasma stabilization. Then, a pulse current was applied to the ion focusing pulse magnetic field generating coil shown in FIG. 2 to apply a magnetic field having an average magnetic field of 1.7 T to measure ions.

As a result, high-speed etching at a maximum of 0.4 μm / min could be performed. This is eight times the etching rate of the conventional method. Also, the wraparound angle is the conventional 1
At least 0.8 ° for 4 °, and extremely excellent partial treatment was obtained without a mask. Table 1 shows the pulse width conditions and the results at this time.

[0013]

[Table 1]

When Al ₂ O ₃ was also processed as a workpiece, it was found that the effect of ion focusing was obtained as shown in Table 2, and that processing without a mask was possible.

[0015]

[Table 2]

Next, a thin film resistor coating of Al was performed using Si as a workpiece. Al (C ₂ H ₅ ) as gas
₂ and the coating treatment was performed in an atmosphere of 1 Torr. The magnetic field for generating highly ionized plasma and for enhancing the anisotropic effect was 0.0875T on average.

The coating was performed by applying an average magnetic field of 1.7 T as a magnetic field for ion focusing. Table 3 shows the results. For example, in the case of τ _on 0.005 ms, the coating speed is 3.
4 [mu] m / min, surface roughness is 0.08μH _max, the thickness difference is uniform was 0.026 / mm ^2.

[0018]

[Table 3]

Next, using SiO ₂ as a work material, flowing CF ₄ + 20% H ₂ as an etching gas, and applying 0.05 Torr
Table 4 shows the test results when a magnetic field was applied in a direction parallel to the traveling direction of the microwaves in order to generate highly ionized plasma in the atmosphere described above. Table 5 shows the test results when a magnetic field was applied in the direction perpendicular to the direction in which the microwaves traveled.

[0020]

[Table 4]

[0021]

[Table 5]

According to Tables 1, 2 and 3, an average pulse magnetic field of 0.0875T is applied to the parallel coil and the vertical coil.
Tables 6, 7, and 8 show the test results when the voltage was continuously applied.

[0023]

[Table 6]

[0024]

[Table 7]

[0025]

[Table 8]

[0026]

According to the present invention, by applying a pulse current to the ion focusing coil and applying a pulse magnetic field, the ions are focused and speeded up, and anisotropic etching and coating without a mask are performed. be able to. Therefore, a highly anisotropic ECR plasma treatment can be performed on a high-density substrate.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an embodiment of the present invention.

FIG. 2 is a sectional view taken along line A-A 'of FIG.

FIG. 3 is an explanatory diagram of a wraparound angle in plasma etching and coating processing.

FIG. 4 is an explanatory diagram of conventional ion scattering.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 workpiece 2 pulse magnetic field generating coil for ion focusing 3 pulse magnetic field generating coil parallel to microwave 4 yoke 5 pulse magnetic field generating coil perpendicular to microwave 6 ion source 7 cooling water drain pipe 8 microwave traveling direction 9 reaction Gas inlet pipe 10 Cooling water inlet pipe 11 Yoke 12 Coil

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yoshinori Shima 768-15 Ozenji Temple, Aso-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Akira Oba 3-205, 1-9-9 Hamasaki, Asaka-shi, Saitama JP-A-3-229859 (JP, A)

Claims (2)

(57) [Claims] 1. The method according to claim 1, wherein the direction is parallel to or perpendicular to the traveling direction of the microwave.
In an ECR plasma processing method using an electron cyclotron resonance (ECR) phenomenon generated by applying a magnetic field directly, or vertically and in parallel , a magnetic field line rotates so that a line of rotation becomes smaller as the diameter of rotation becomes closer to a workpiece. Pulse voltage is applied to the rotating magnetic coil with a funnel-shaped center
Thus by rotating the magnetic field lines to pressure, the ions in the plasma converging along the funnel, ECR plasma processing method characterized by machining against the workpiece body surface squeezing ion stream. 2. A magnetic field parallel to the traveling direction of the microwave is generated.
Coils or magnets perpendicular to the direction of microwave travel.
2. A pulse voltage is applied to a coil for generating a field.
The ECR plasma processing method described in the above.