Radial line slot antenna structure in plasma surface treatment device for semiconductor substrate

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to a structure of a radial line slot antenna for generating the plasma by microwaves in a plasma surface treatment apparatus in which a semiconductor substrate such as a silicon wafer is surface-treated with plasma.

【0002】

[Conventional technology]

In general, a plasma surface treatment device using this type of radial line slot antenna forms a flat recess on the lower surface of a metal antenna guide such as aluminum, as is well known in the past. A metal slot plate formed by laterally loading a dielectric plate formed of quartz or alumina ceramic into a disk shape in the recess and drilling a large number of slot holes on the lower surface side of the dielectric plate. Is arranged so as to extend parallel to the dielectric plate, and a microwave waveguide having a built-in conductor wiring to the slot plate is connected to the central portion of the upper surface of the antenna guide to form a radial line slot antenna. Then, by introducing microwaves into the antenna guide, the microwaves are spread outward by the dielectric plate in the radial direction so as to cover the entire area, and then from each slot hole in the slot plate. By ejecting downward, plasma is generated between the semiconductor substrate and the semiconductor substrate arranged below the semiconductor substrate, and the plasma forms various coatings on the surface of the semiconductor substrate, or the surface of the semiconductor substrate. Surface treatment such as etching is performed.

【0003】

In this case, in the radial line slot antenna in the conventional plasma surface treatment apparatus, the slot plate arranged on the lower surface side of the dielectric plate is extended outward until the outer peripheral edge portion thereof is brought into close contact with the lower surface of the antenna guide. It is configured to be attached to the antenna guide by fastening a plurality of points on the circumference with set screws.

【0004】

[Problems to be Solved by the Invention]

However, since the slot plate is heated to a high temperature due to heat from plasma or the like, the throttle plate is attached to the antenna guide at a plurality of locations on the outer peripheral edge of the slot plate as described above. Since the dielectric plate on the upper surface of the slot plate is made of quartz or alumina ceramic having low thermal conductivity, heat release from the slot plate is exclusively used for the antenna guide. On the other hand, the contact is limited to the outer peripheral edge only, and thermal expansion occurs in the inner portion due to heat storage, so that the inner portion of the slot plate than the outer peripheral edge is downward due to the thermal expansion. It is distorted and deformed into a bulging shape, and the space between it and the semiconductor substrate arranged below it is narrow and wide, so that the emitted microwaves become non-uniform. Therefore, the plasma formed in the process area of the semiconductor substrate becomes non-uniform and unstable, so that the surface of the semiconductor substrate can be unevenly processed.

【0005】

Therefore, in recent radial line slot antennas, in addition to screwing the outer peripheral edge portion of the slot plate to the antenna guide, a plurality of locations inside the slot plate are also screwed to the dielectric plate. However, even with this configuration, the slot plate is distorted and deformed so as to bulge downward in the portion between the set screws. Therefore, the strain deformation due to thermal expansion in this slot plate is fundamental. There was a problem that it could not be eliminated.

【0006】

An object of the present invention is to provide an apparatus capable of reliably reducing strain deformation due to thermal expansion in the slot plate.

【0007】

[Means for solving problems]

In order to achieve this technical problem, the present invention presents "a metal antenna guide having a flat recess formed on the lower surface, a disk-shaped dielectric plate loaded in the recess, and a lower surface of the dielectric plate. In a radial line slot antenna composed of a metal slot plate arranged so that an outer peripheral edge portion is attached to the antenna guide on the side, and a waveguide for introducing microwaves is connected to the antenna guide. Expansion absorption formed by drilling a punch hole in at least a portion of the slot plate adjacent to the inside of the attachment portion with respect to the antenna guide so as to leave a deformable narrow piece connecting the outer portion and the inner portion. The part is provided so as to extend in a ring shape over the entire circumference. "

【0008】

[Action / Effect of Invention]

Since the slot plate is attached to the antenna guide at the outer peripheral edge of the slot plate, the slot plate is an inner part due to thermal expansion in the radial direction when it receives heat. Will be distorted and deformed so that it swells downward.

【0009】

On the other hand, as described above, at least in the portion of the slot plate adjacent to the inside of the attachment portion with respect to the antenna guide, a narrow piece that connects the outer portion and the inner portion and is deformable is left. In the case where the expansion / absorption portion formed by drilling a hole is provided so as to extend in a ring shape over the entire circumference, the thermal expansion in the radial direction when receiving heat is the expansion. Since it can be absorbed by the deformation of each narrow piece in the absorbing portion and the thermal expansion can be significantly reduced to the outside, the portion of the slot plate inside the expansion absorbing portion is directed downward. It is possible to surely reduce the distortion and deformation so as to swell.

【0010】

Therefore, according to the present invention, when the surface treatment of the semiconductor substrate with plasma is performed, there is an effect that the occurrence of treatment unevenness due to the strain deformation of the slot plate can be surely and significantly reduced.

【0011】

By the way, when a punch hole for forming a narrow piece in the expansion / absorption portion is formed in the slot plate, microwaves are also ejected from the punch hole. The homogenization of microwaves will be hindered, but as described in claim 2, the punch hole in the expansion / absorption portion is closed with an antenna guide or provided in a slot plate. By configuring it so that it is closed with a metal plate, it can be solved very easily.

【0012】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described with reference to the drawings of FIGS. 1 to 4.

【0013】

In this figure, reference numeral 1 indicates a chamber in a plasma surface treatment apparatus, and reference numeral 2 indicates an aluminum antenna guide attached to the upper surface of the chamber 1 via an insulator 3, and the lower surface of the antenna guide 2 is shown. A flat recess 4 is formed in the antenna guide 2, and a waveguide 5 for introducing microwaves into the recess 4 is connected to the upper surface of the antenna guide 2.

【0014】

Reference numeral 6 indicates a disk-shaped dielectric plate loaded in the recess 4 in the antenna guide 2, and a metal slot plate 7 in which a large number of slot holes 8 are bored is formed on the lower surface side thereof. The outer peripheral portion is arranged so as to be in close contact with the lower surface 2a of the antenna guide 2, and the slot plate 7 is fastened to the antenna guide 2 with the outer peripheral portion with a plurality of screws 9. It is detachably attached by fastening it.

【0015】

Further, the conductor wiring 10 inserted in the waveguide 5 is configured to pass through the dielectric plate 6 and be connected to the slot plate 7 arranged on the lower surface side thereof.

【0016】

Below the slot plate 7, as shown by the alternate long and short dash line, a lower electrode 12 on which the semiconductor substrate 13 to be processed is placed is arranged on the upper surface.

【0017】

Then, in the present invention, as shown in FIG. 3 or 4, a portion of the slot plate 7 inside and adjacent to the attachment portion by the plurality of screws 9 to the antenna guide 2 is formed. An expansion / absorption portion 11 formed by drilling a punching hole 11b so as to leave a deformable narrow piece 11a connecting the outer portion and the inner portion is provided so as to extend in an annular shape over the entire circumference. ..

【0018】

With this configuration, the thermal expansion in the radial direction when heat is received by the slot plate 7 can be absorbed by the deformation of each narrow piece 11a in the expansion absorption unit 11, and this thermal expansion can be absorbed. Since it is possible to reduce the extent to which it extends to the outside of the expansion / absorption portion 11, it is possible to reliably reduce the distortion and deformation of the slot plate 7 inside the expansion / absorption portion 11 so as to bulge downward. is there.

【0019】

In this case, it goes without saying that the annular expansion / absorption unit 11 is not limited to one as shown in the drawing, and may be double or triple.

【0020】

Further, by providing the expansion / absorption portion 11 of the slot plate 7 in a portion of the outer peripheral portion of the slot plate 7 that abuts on the lower surface 2a of the antenna guide 2, each punching hole 11b in the expansion / absorption portion 11 is provided as an antenna. It is configured to be closed by the guide 2, or each punching hole 11b in the expansion / absorbing portion 11 is closed by a metal body provided on either one or both of the front surface and the back surface of the slot plate 7. Since it is possible to prevent the leakage of microwaves from each of the extraction holes 11b, it is possible to avoid disturbing the ejection flow of microwaves from each of the slot holes 8 in the slot plate 7.

[Simple explanation of drawings]

[Figure 1]

It is a vertical sectional front view which shows the embodiment of this invention.

[Figure 2]

It is a figure which shows the disassembled state of FIG.

[Fig. 3]

FIG. 2 is a magnified bottom view of III-III in FIG.

[Fig. 4]

It is an enlarged bottom view which shows another form.

[Explanation of symbols]

1 chamber 2 Antenna guide 4 recesses 5 Waveguide 6 Dielectric plate 7 slot board 8 slot holes 9 screws 10 Conductor wiring 11 Expansion absorber 11a narrow piece 11b Drilling hole