JPH04120276A - Surface treating device - Google Patents

Abstract

PURPOSE:To improve the efficiency of utilizing the electric power of electromagnetic waves in plasma generation by improving the coupling between the electromagnetic waves and plasma generating chamber in an ECR device and introducing the electromagnetic waves in the state of linearly polarized waves into this chamber. CONSTITUTION:A magnetic field B parallel with the side wall of the plasma generating chamber 1 is produced by, for example, air core coils 8, 8'. A metallic plate 100 having a coupling hole 10 of a rectangular shape for introducing the electromagnetic waves into the chamber 1 is joined to the terminal of a square waveguide 9. The coupling hole 10 may be shaped to an oval, elliptic or cocoon shape. After the inside of the generating chamber 1 and a treating chamber 2 is evacuated to a vacuum by a discharge system 5, a gas for treatment is introduced by gas introducing systems 6, 7 into the chambers and prescribed pressures are maintained in the chambers 1, 2. The electromagnetic waves are then impressed to the chamber 1 and are introduced through a three-dimensional circuit element, such as tuner 9', into the waveguide 9. The electromagnetic waves are radiated through the coupling hole 10 into the generating chamber 1 and the high-density plasma is generated by the small electric power if the reflected waves from the coupling hole 10 are negated by the tuner 9'.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a surface treatment apparatus, for example, a plasma etching, plasma CVD apparatus, photoetching, photoCVD
It is highly effective when applied to single-stage etching, sputtering equipment, sputter etching equipment, and combination equipment thereof.

(Prior art and its problems) As the prior art of the present invention, for example, Japanese Patent Application Laid-Open No. 55-141729 by Matsuo et al.
There is an invention of an ion shower device disclosed in Japanese Patent No. 975. These inventions are widely put into practice as so-called ECR devices. A schematic diagram of the device is shown in FIG.

This conventional ECR device has several drawbacks. That is, when introducing electromagnetic waves into the plasma generation chamber 1 through the waveguide 9, a TE, rectangular waveguide (or TE,
The end face of the circular waveguide (9) is directly connected to the plasma generation chamber 1 via an introduction window 11 made of a dielectric plate such as quartz or alumina, which also serves as a vacuum window. Therefore, when the plasma generation chamber 1 is viewed as a resonator, this electromagnetic wave introduction part does not satisfy the optimum conditions as a coupling hole, and has a low Q value, that is, extremely poor power utilization efficiency.

Further, since a shift occurs in impedance matching at the electromagnetic wave introduction window 11, electromagnetic wave loss occurs, and the proportion of the electromagnetic wave power that effectively propagates into the plasma generation chamber 1 is small. The loss in the waveguide 9 and the three-dimensional circuit section is large. Due to this drawback, when the power of the electromagnetic waves applied to the plasma generation chamber 1 is increased in order to increase the density of the plasma 12, the loss of electromagnetic waves at the introduction window 11 is large, so the amount of heat generated increases. Various troubles, including destruction, are likely to occur.

In addition, in the conventional device, since the area of the window portion 11 is large, it is suitable for generating plasma 12 uniformly in the plasma generation chamber 1, but it is difficult to concentrate the plasma in a small volume of space to increase the density. It wasn't suitable for trying.

(Objective of the Invention) An object of the present invention is to provide a surface treatment apparatus that improves the utilization efficiency of electromagnetic wave power in plasma generation and enables generation of high-density plasma with small electric power.

(Means for Solving the Problems) The present invention provides a plasma generation chamber capable of introducing a processing gas and maintaining it in a reduced pressure state, and a means for introducing electromagnetic waves into the plasma generation chamber to generate plasma of the processing gas. and,
A means for generating a magnetic field having a component parallel to the direction of propagation of electromagnetic waves in a plasma generation chamber, and a means for placing an object to be processed in the plasma generation chamber or a processing chamber installed in connection with the chamber. The above object is achieved by a surface treatment apparatus configured such that electromagnetic waves are introduced into a plasma generation chamber in a linearly polarized state.

A conductive plate whose thickness is sufficiently smaller than the wavelength of the M electromagnetic wave is installed at right angles to the direction of propagation of the electromagnetic wave between the plasma generation chamber and the three-dimensional circuit element installed to introduce electromagnetic waves into it. In addition, the plate is configured to pass through a slit-shaped coupling hole with a long side in a direction perpendicular to the oscillating electric field on the waveguide side surface of the plate, and to introduce electromagnetic waves into the plasma chamber from the coupling hole. The length of the long side of the coupling hole should be approximately λ/2 (λ is the free space wavelength of electromagnetic waves), and the shape of the coupling hole should be selected to be rectangular, oval, elliptical, or cocoon-shaped. , an improved device is obtained in which improved processing uniformity is achieved.

Further, when an electromagnetic horn is installed between the coupling hole and the plasma generation chamber, the device becomes even more efficient.

(Operation) The gist of the present invention is to improve the coupling between electromagnetic waves and a plasma generation chamber that is a resonator thereof.

Several methods can be considered to improve the coupling between the waveguide and the plasma generation chamber, but this invention focuses on the fact that slot antennas efficiently radiate electromagnetic waves in the microwave region, and developed this method. This was used to improve the efficiency of supplying electromagnetic waves to the plasma generation chamber.

In the conventional device shown in FIG. 8, it is difficult to perfectly match the electromagnetic waves during discharge, and even when it appears that matching has been achieved, the window 11 and the waveguide 9
The generation of heat due to loss of electromagnetic waves is large in areas such as areas, and even if large amounts of power are injected, it has been impossible to generate plasma efficiently (high density).However, according to the configuration of the present invention, the efficiency of supplying electromagnetic waves can be improved As a result, the processing speed when applying the same power has been improved due to the improved power usage efficiency.

(Example) Figures 1a (front sectional view) and b (partial side view) schematically show an example of the present invention, in which 1 is a plasma generation chamber, 2 is a processing chamber, and 3 Reference numeral 4 indicates a holder for an object to be processed, 9 is a rectangular waveguide, and 11 is a vacuum window made of quartz, alumina, or the like.

A magnetic field B is created in the plasma generation chamber 1 by an air-core coil 8.8' (which may be one or more than two). In this embodiment, the magnetic field B is set in a direction parallel to the side wall of the plasma generation chamber 1 by two air-core coils in a so-called mirror magnetic field shape. At the end of the rectangular waveguide 9, there is a coupling hole 1 for introducing electromagnetic waves into the plasma generation chamber.
A metal plate 100 with 0 is joined. Note that this metal plate 100 may be installed on the vacuum chamber 1 side of the vacuum window 11. A typical example of the shape of the coupling hole 10 is shown in Figure 3 as
bs Shown in CXd. They are rectangular, oblong, oval, and cocoon-shaped. As shown in FIG. 1, this embodiment uses a rectangular coupling hole with a width h1 and a length α.

To operate this device, the plasma generation chamber 1 and the processing chamber 2 are evacuated using the exhaust system 5, and then a processing gas is introduced using the gas introduction system 6.7. The exhaust speed is adjusted to keep the inside of the plasma generation chamber 1 and the inside of the vacuum chamber 2 at a predetermined pressure. Next, electromagnetic waves are applied to the plasma generation chamber 1. Here, microwaves of 2.45 GHz are supplied as electromagnetic waves.

Electromagnetic waves output from an electromagnetic wave generator (not shown) are transmitted to an isolator (not shown) and a power monitor (not shown).
The light is then guided to the waveguide 9 through a three-dimensional circuit element such as a tuner 9'. Using this tuner 9', connect hole 1
If the reflected wave from 0 is canceled, the electromagnetic wave is radiated into the plasma generation chamber 1 through the coupling hole 10. If the propagation mode of the waveguide 9 at this time is the normally used TE or s mode, the coupling hole 10 is parallel to the E plane of the waveguide, as shown in the side view of FIG. It is best to set it up.

The best radiation efficiency can be obtained by selecting the length 1 of the coupling hole 10 to be approximately λ/2. The width of the coupling hole 10 is an arbitrary value smaller than λ/2, and is selected so as to provide the best radiation efficiency.

The best value for the width of the coupling hole varies depending on the shape of the plasma generation chamber 1 and other factors.

With the above operations, plasma 12 is generated in the plasma generation chamber 1.
The shape of the plasma 12 is shown in FIGS. 5a (front view) and 5b (sectional view taken along line AA').

The electromagnetic waves radiated into the plasma generation chamber 1 from the coupling hole 10 have directivity that depends on the shape of the coupling hole 10, and the shape of the plasma is flat. When the magnetic field is a mirror magnetic field as described above, the shape is bulged at the center as shown in FIG. 5a.

In this embodiment, if the uniformity of processing of the workpiece 4 is a problem, the shape of the coupling hole 10 may be changed, for example, as shown in FIGS. 3b-d.
It is also possible to change the shape of the plasma and improve its uniformity by making it into an oval shape, an ellipse shape, etc. as shown in FIG.

Also, by arranging the air-core coils 8,8' in a Helmholtz configuration, plasma with good uniformity can be obtained.

In addition, the plasma of the conventional device is! As shown in the cross-sectional view of FIG. 5C, it has a rotating curved surface shape.

Another embodiment of the present invention is shown in FIGS. 2a (front sectional view) and 2b (partial side view).

A movable shorting plate 13 is installed at the end of the plasma generation chamber 1 opposite to the electromagnetic wave introducing section, and the processing chamber 2 is installed at right angles to the plasma generation chamber 1, unlike the case shown in FIG. It is being The reason for configuring the apparatus in this way is to reduce the impact of charged particles incident on the substrate 4 from the generated plasma, and to reduce the impact on the substrate 4 by exclusively using the neutral active species in the plasma and the light emitted from the plasma. This is because we want to perform surface treatment.

In this case, the shape of the plasma should be flat so that it spreads with good uniformity in the direction parallel to the surface of the substrate 40 to be processed and is thinly concentrated in the perpendicular direction. This is desirable in terms of improving the efficiency of seed use.

In the case of the device of the present invention, by setting the width of the coupling hole 10 to be as small as possible, it is possible to easily obtain a plasma having a shape suitable for the above purpose. Since the position can be moved, the best plasma generation conditions can always be created even when the shape of the coupling hole 10 changes over a wide range.

In the apparatus shown in FIG. 2, a target 20 is further added on top of the target as shown by the dotted line, and a power source 21 (alternating, direct,
If power is supplied by RF or microwave (either RF or microwave), this can also be used as a sputtering device. In this case, since almost no charged particles flow into the substrate 4, a thin film with very little damage or change in film composition can be produced.

Further, if it is desired to obtain an appropriate charged particle impact according to the needs of the target process, the purpose can be achieved using the power source 22 (alternating current, direct power, RF, or microwave).

Further, the target may be placed on the movable shorting plate 13. In that case, the power source 22 may be moved to the movable shorting plate 13 and a bias voltage may be applied from there.

FIG. 4 further shows a front sectional view of another embodiment of the invention. The basic configuration is the same as in FIG. 2, but the vacuum window 11
An electromagnetic horn 14 is installed on the vacuum chamber side. By installing the electromagnetic horn 14, the plasma generation chamber 1 is connected to the waveguide 9.
The characteristic impedance changes continuously throughout the process, and the radiation efficiency of electromagnetic waves can be further improved compared to the device of the embodiment shown in FIG. 1.2. When the width of the inlet of the electromagnetic horn 14 is made the same as the optimum width of the coupling hole described above, the same characteristics can be obtained even if the coupling hole 10 is not provided and the electromagnetic horn is directly connected to the waveguide 9. is obtained.

Note that the width of the E plane at the entrance of the electromagnetic horn 14 at this time is set to be the same as or larger than the above 1. Electromagnetic horn 14
Ideally, the depth length S should be about 2λ, but sufficient effects can be obtained even if it is shorter.

The electromagnetic horn 14 may be constructed of a curved surface such as a paraboloid or the like, which is usually composed of four flat plates.

In the device of this embodiment, most of the charged particles in the plasma flow into the contact surface 23 where the plasma and the electromagnetic horn come into contact, and the flow into the window 11 is drastically reduced.

Therefore, there is almost no overheating or damage to the window 11 (and the surface of the object to be processed can be stably processed with high-density plasma.

Furthermore, by placing an object to be etched on the holder 3 and introducing a gas suitable for etching, this apparatus can be used as an active ion etching apparatus or a plasma etching apparatus. When it is desired to adjust the temperature of the object to be processed, it is heated or cooled by a device provided in the holder 3 (by passing a coolant instead of a heater).

To reduce the flow of charged particles toward the window (if desired, apply a local magnetic field 2 to that area, as illustrated in Figure 4).
Further effects can be obtained by providing 5.

FIG. 6 shows a front cross-sectional view of a coupling portion of still another embodiment. Although only the electromagnetic wave introducing section is shown, the configurations of the plasma generation chamber 1 and the processing chamber 2 are the same as those of the previous embodiment. In this embodiment, a cavity resonator 15 is newly provided, and a coupling hole 16 is opened between it and the waveguide 9.

The depth X of the cavity resonator 15 is set to (n/2) λg (where λg is the internal wavelength of the electromagnetic wave, and n is an integer), and the resonance mode is set to TE and lln. The point that electromagnetic waves are radiated from the coupling hole 10 to the plasma generation chamber 1 is the same as in the previous embodiments, but by installing the cavity resonator 15 in front of the coupling hole 10, the radiation efficiency is greatly improved. Incidentally, if the coupling hole 16 of the cavity resonator 15 is designed in an optimal coupling state, the tuner 9' becomes unnecessary. Further, the resonance mode of the cavity resonator 15 may be designed to be another mode.

FIG. 7 shows a front view of an electromagnetic wave introduction section of still another embodiment. 90 is a tapered waveguide provided at the tip of the rectangular waveguide 9. The width of the E plane at the portion where the tapered waveguide 90 contacts the window 11 is made to be the same as the width of the E plane of the electromagnetic horn 14 of the embodiment shown in FIG. Electromagnetic horn 14
Since the shape of the inlet of the tapered waveguide 90 and the outlet of the tapered waveguide 90 are the same, a coupling hole is not necessary (and the electromagnetic waves can be radiated into the plasma generation chamber 1 more efficiently).

(Effects of the Invention) According to the apparatus of the present invention, it is possible to improve the utilization efficiency of electromagnetic wave power in the plasma generation chamber and to change the shape of plasma according to the process. Therefore, it is possible to provide a surface treatment apparatus that has good power utilization efficiency, in other words, can perform faster processing with the same amount of power.

[Brief explanation of the drawing]

Figures a and b in Fig. 1.2.4 are a schematic front sectional view and a sectional view of the central part of the surface treatment apparatus according to the embodiment of the present invention, respectively. Figure 3 ASBS/CX d is an example of the shape of the coupling hole. FIG. 5a shows the shape of the plasma generated by the device of the invention. FIG. 5 is a similar diagram of a conventional device. Figure 6.7 is a front cross-sectional view of a joint according to another embodiment of the invention. FIG. 8 is a schematic front sectional view of a conventional ECR type surface treatment apparatus. 1... Plasma generation chamber, 2... Processing chamber, 3... Holder 4... Processed object, 5... Exhaust system, 6.7... Gas introduction system, 8.8'... Air core solenoid coil, 9... Rectangular waveguide, 9'... Tuner 10・・・・・・Connection hole, 11・・・・・・
・Vacuum window.

Claims (8)

[Claims] (1) A plasma generation chamber capable of introducing a processing gas and maintaining it in a reduced pressure state, a means for introducing electromagnetic waves into the plasma generation chamber to turn the processing gas into plasma, and a component parallel to the direction of propagation of the electromagnetic waves. A surface treatment apparatus comprising: means for generating a magnetic field within the plasma generation chamber; and means for placing a workpiece within the plasma generation chamber or a processing chamber installed in connection with the chamber; A surface treatment apparatus characterized in that electromagnetic waves are introduced into the plasma generation chamber in a linearly polarized state. (2) A conductive plate is installed between the plasma generation chamber and the three-dimensional circuit element installed to introduce electromagnetic waves therein, at right angles to the traveling direction of the electromagnetic waves; The surface according to claim 1, characterized in that the electromagnetic wave is introduced into the plasma chamber through a slit-shaped coupling hole having a long side in a direction perpendicular to the oscillating electric field in the front, and through the coupling hole. Processing equipment. (3) The surface treatment apparatus according to claim 2, wherein the length of the long side of the coupling hole is approximately λ/2 (λ is the free space wavelength of electromagnetic waves). (4) The surface treatment device according to claim 2 or 3, wherein the coupling hole has a rectangular shape. (5) The surface treatment device according to claim 2 or 3, wherein the coupling hole has an oval shape. (6) The surface treatment device according to claim 2 or 3, wherein the coupling hole has an elliptical shape. (7) The surface treatment device according to claim 2 or 3, wherein the shape of the coupling hole is a cocoon shape. (8) Claims 1, 2, and 3, characterized in that an electromagnetic horn is installed between the coupling hole and the plasma generation chamber.
, 4, 5, 6, 7 or 8.