JPH05345990A - Microwave discharge reaction device - Google Patents

Abstract

PURPOSE:To additionally reduce the size of the device using flat planar electrodes in a vacuum vessel and to improve the treating capacity thereof by constituting these electrodes as a pair facing each other and symmetrically setting the positional relation of the magnetic poles of the magnetic circuits thereof. CONSTITUTION:Two plasma generating mechanisms 2, 3 constituted by combining the flat planar electrodes 7 to which microwaves are supplied through coaxial lines 9 and which have slits and the magnetic circuits 10 which consist of plural cylindrical permanent magnets are so provided that the respective electrodes 7 face each other apart a spacing. A substrate holding mechanism 14 is provided between the respective electrodes 7 and substrates 16, 17 are mounted on the front and rear surfaces of this substrate holder 15. The magnetic poles of the magnetic circuits 10 are so disposed that the magnetic poles facing each other are the same poles. Consequently, the magnetic fields by the respective magnetic poles are zero between the electrodes 7 and 7 and the spacing required for uniformizing the plasma is narrowed. The treatment of the substrates with the uniform and high-density plasma is possible and the treating speed is increased. Since the provision of two sheets of the substrates is possible, the treating capacity is increased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave discharge reactor, and more particularly to a microwave discharge reactor suitable for application to a dry etching apparatus, a plasma CVD apparatus, a sputtering apparatus, a surface reforming apparatus and the like.

[0002]

2. Description of the Related Art Conventionally, for example, JP-A-55-141729.
ECR (Electron Cyclotron Resonance) disclosed in Japanese Patent Publication
Various devices have been proposed as discharge reaction devices that utilize electromagnetic waves in the microwave range, such as devices. Generally, in order to efficiently generate plasma in the discharge chamber with this type of discharge reaction device, it is necessary to design the discharge chamber so that the discharge chamber acts as a resonator for the frequency of the microwave used. .. Therefore, the size of the discharge chamber is limited by the microwave wavelength (about 12 cm for 2.45 GHz microwave, which is often used), and the size of the discharge chamber cannot be determined by simply increasing the size of the discharge chamber. The plasma becomes non-uniform due to the generation of standing waves, etc., and it has been impossible to uniformly process a large-area substrate.

On the other hand, the size of the substrate to be processed has become larger and larger in recent years, and it becomes necessary to uniformly process a substrate having a size of several times the wavelength of the microwave of 2.45 GHz. Further, the conventional discharge reaction device generally employs a structure in which a microwave is introduced into the discharge chamber by using a waveguide. Since the size of the waveguide is determined depending on the frequency region used, there are large dimensional restrictions in the device design, and the reliability of the microwave introduction window was not sufficient.

On the other hand, a coaxial tube was used to introduce microwaves, and a cylindrical electrode having a large number of slits was used as an antenna for microwave radiation to achieve large-area processing. The device is also being developed.
This device is, for example, A. Yonesu et al. Production of a larg
e-diameter uniform ECR plasma with a Lisitanocoil "
Jpn.J.Appl.Phys., 27 (1988) L1746.). Further, as disclosed in JP-A-1-159397,
It has also been attempted to uniformly process a large area by using a plate-shaped electrode having a large number of slits as an antenna.

By the way, in order to generate a plasma with good uniformity over a large area by using the cylinder having a large number of slits as an electrode, the EC in the whole area of the cylinder is EC.
For the R condition, that is, for microwaves of 2.45 GHz, it is necessary to generate a magnetic field with a magnetic flux density of 875 Gauss in the direction parallel to the slit. For example, in order to process a substrate having a diameter of 300 mm with good uniformity, A. Yonesu et al. According to the above document, it is necessary to use a cylindrical electrode having an inner diameter of 400 mm. In order to generate a magnetic field of 875 Gauss in such a large electrode with good uniformity, a huge air-core coil is required, which is a major obstacle to practical use of the discharge reaction device using the cylindrical electrode. It was.

Further, in the discharge reaction device disclosed in Japanese Patent Laid-Open No. 1-159397, which uses a flat plate-shaped electrode having a large number of slits as an antenna, a large space is required to generate a magnetic field in a direction perpendicular to the electrode. A core coil is required, and the plasma generation efficiency cannot be said to be good in the conventional configuration that does not use such an air core coil.

Further, as a drawback common to the above-mentioned three types of conventional devices, since the magnetic field used for generating plasma is continuous up to the region where the substrate to be processed is installed, the magnetic field in the plasma generating region is large. The non-uniformity of the plasma density due to the conditions and standing waves is directly reflected in the distribution of the ion current density on the substrate to be processed, which is an obstacle to performing uniform processing. In addition, since the trajectories of the ions incident on the substrate to be processed are along the direction of the magnetic field, the uniformity of the magnetic flux density is uniform over the entire surface of the substrate to be processed, especially when performing fine processing by dry etching utilizing the reactivity of ions. It is necessary to arrange the coils so that the direction of the magnetic field is also vertical over the entire surface of the substrate to be processed. In order to realize this state, it is generally impossible with a single air-core coil, and the structure of the micro magnetic discharge reactor becomes very complicated. A recently proposed discharge reactor using plasma near the ECR condition region (S. Samukawa
et al. “Extremely high-selective electron cyclot
ron resonance plasma etching for phosphorus-doped
polycrystaline silicon. ”Appl.Phys.Lett.57 (1990) 4
Even in 03.), the above problems have not been essentially solved.

[0008]

SUMMARY OF THE INVENTION In order to solve each of the above problems, the present applicant previously applied for a microwave discharge reaction chamber that solves these problems (Japanese Patent Application No. 2-400904).
No., filed on December 7, 1990). This microwave discharge reactor does not require a huge air-core coil and does not require the coil, so that it can be manufactured in a small size and at a low cost with a simple structure, and a plasma with good uniformity can be obtained. Since it is generated and the generation efficiency is good, a substrate having a large area can be uniformly processed, which is extremely practical.

By the way, while the substrate processing is becoming finer, recently, the ratio of the manufacturing cost to the production cost tends to further increase, and it is smaller and more compact, and more substrates can be processed faster. There is a demand for a manufacturing apparatus whose manufacturing cost is kept low.

Therefore, in consideration of the above requirements, further improvement of the microwave discharge reactor proposed by the present applicant is required.

It is an object of the present invention to have a high substrate throughput.
An object of the present invention is to provide a microwave discharge reactor which can be manufactured at low cost and which is small and compact.

[0012]

A microwave discharge reactor according to the present invention comprises a vacuum container having a mechanism for holding the inside in a depressurized state and a mechanism for introducing gas, and a microwave supplied by a coaxial line for vacuuming. A flat plate-shaped electrode having at least one slit having a predetermined length and width radiating into the container, and a concentric position sharing a center with the electrode, and the magnetic field direction of the electrode is perpendicular to the electrode. A plurality of ring-shaped magnetic field generating means that generate magnetic fields in the same direction as the length direction of the slit are arranged in the vicinity, and a plasma generating mechanism is configured by combining the electrodes and the magnetic field generating means.
At least one set of plasma generating mechanisms is arranged so that one electrode is opposed to each other, and a substrate holding mechanism is disposed in the middle of each electrode so as to face each of the electrodes. The substrate is held on each surface of the substrate holding mechanism, and plasma is generated in the space around each surface.

In the above structure, preferably, the magnetic field generating means of the plasma generating mechanism have magnetic poles facing each other, and the magnetic poles facing each other have the same pole.

[0014]

In the microwave discharge reactor according to the present invention, a flat plate electrode is used in comparison with the device previously proposed by the applicant.
And the electrodes are arranged to face each other,
A plasma generating mechanism is configured corresponding to each electrode. Further, the two flat plate-shaped electrodes arranged to face each other are arranged at a predetermined interval, and the magnetic field generating means provided in each electrode, that is, the magnetic circuit, has a symmetrical magnetic pole positional relationship. Will be placed. As a result, the magnetic field generated by the opposed magnetic poles has a greater strength attenuation method than when there is no opposed magnet, and becomes zero in the middle of the two electrodes. Therefore, the distance required for the plasma to be uniform can be shortened, and even if the distance between the electrode and the substrate is narrow, it is possible to perform the substrate treatment with the uniform and high-density plasma. Therefore, the substrate processing speed is increased. Further, since the substrate holding mechanism can be equipped with two substrates corresponding to the respective electrodes, the substrate processing capability is enhanced.

[0015]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is an internal configuration diagram showing an embodiment of a microwave discharge reaction device according to the present invention. Reference numeral 1 denotes a vacuum container used as a microwave discharge reaction chamber, and the vacuum container 1 is actually shown in cross section. Plasma generation mechanisms 2 and 3 are installed on the upper wall portion and the lower wall portion of the vacuum container 1 in the figure.
Further, the vacuum container 1 is provided on the left side wall side of the vacuum container 1 in the figure.
An exhaust system 4 is installed to bring the inside of the chamber into a required decompressed state, and a reactive gas introduction mechanism 6 is provided through a valve 5 on the right wall side.
Is installed.

The plasma generating mechanisms 2 and 3 are basically composed of the same elements. FIG. 2 shows a front view of the electrode portion of each plasma generation mechanism. In each plasma generation mechanism, 7 is an electrode made by processing a slit 8 on a flat plate made of a conductive member such as metal. The overall shape of the electrode 7 is flat and has, for example, a circular shape. The electrode 7 is composed of an external electrode 7a and an internal electrode 7b which are located at a position sandwiching the slit 8. In practice, the external electrode 7a and the internal electrode 7b are made of a single metal plate. Due to its shape, the slit 8 is divided into the following three parts. One is a slit portion 8a radially extending from the center of the circular electrode 7 in the radial direction, and the other is a radial slit portion 8a.
There are two kinds of circumferential slit portions connecting the two, that is, a slit portion 8b connecting the radial slit portions 8a with a small radius near the electrode center and a slit portion 8c connecting with a large radius near the electrode periphery. In this embodiment, the slit 8 is a gap having a uniform predetermined width formed when the external electrode 7a and the internal electrode 7b are combined. In FIG. 1, illustration of members for assembling the external electrodes 7a and the internal electrodes 7b is omitted. The width of the slit 8 is practically determined to be an optimum value, but it is necessary to make it sufficiently shorter than the wavelength of the microwave. The length of the slit 2 is also set to an optimum value based on experiments. The shape pattern of the slit 8 described above is an example, and is not limited to this. In the above, the flat plate-shaped electrodes 7 of the two plasma generating mechanisms are arranged so as to face each other in parallel at a predetermined interval.

A coaxial line 9 is used to supply the microwave to the plate-shaped electrode 7. In the coaxial line 9, the internal electrode 7
A central conductor 9A is connected to the center of b, and power is supplied by grounding the external electrode 7b. Reference numeral 10 is a magnetic circuit including a plurality of cylindrical (including ring-shaped) permanent magnets. The magnetic circuit 10 is arranged at a slight distance from the portion of the electrode 7 to which the microwave is supplied, and in the illustrated example, the conductive flat plate 11 is held at the ground potential via the outer conductor 9B of the coaxial line 9. Fixed on one side. The cylindrical permanent magnets have different diameters and are arranged concentrically. Further, the positions of the N pole and the S pole in each of the permanent magnets are alternately inverted. Note that the configuration shown in FIG. 1 is conceptual,
As for the specific coupling structure of the coaxial line 9 and the mounting structure of the magnetic circuit 10, any known structure can be adopted. The magnetic poles in each magnetic circuit 10 of the plasma generating mechanisms 2 and 3 are arranged so that the facing magnetic poles have the same pole. Reference numeral 12 is a microwave power supply mechanism that supplies power to the electrode 7. Again 1
3 is disposed between the central conductor 9A and the outer conductor 9B,
It is an insulator for maintaining the degree of vacuum in the vacuum container 1.

The plasma generating mechanisms 2 and 3 configured as described above are arranged so as to have a symmetrical structure.

In order to operate the above-mentioned microwave discharge reactor, the inside of the vacuum vessel 1 is evacuated to a desired vacuum state by the exhaust system 4, and then a predetermined gas is evacuated from the reactive gas introducing mechanism 6 through the valve 5. It is introduced into the container 1. Next, the gas flow rate and the exhaust speed of the exhaust system 4 are appropriately adjusted to obtain a predetermined gas pressure. The gas pressure at this time is usually
It is desirable that the pressure is about 10 ^-2 to 10 ^-6 Pa. Under such conditions, microwave discharge is generated in the vacuum container 1.
A microwave is supplied from the microwave power supply mechanism 12 including a microwave circuit element such as an isolator, a power monitor and a tuner to the electrode 7 through the coaxial line 9. The outer conductor 9B of the coaxial line 9 penetrates the upper wall portion of the vacuum container 1 while maintaining the vacuum sealed state, and extends to the vicinity of the electrode 7.

With the above configuration and operation, the microwave is supplied to the electrode 7 via the coaxial line 9 and is radiated into the internal space of the vacuum container 1 by the action of the slit 8 to generate a strong vibration electric field. The reactive gas introduced into the vacuum container 1 is ionized by the electrons accelerated by this electric field and becomes a plasma state. The electrons in the plasma are heated resonantly by the interaction of the electric field with the magnetic field (heating by the ECR action), ionize other neutral particles one after another, and generate high-density plasma. A discharge reaction is performed using this plasma.

A substrate holding mechanism 14 is arranged at an intermediate position between the plasma generating mechanisms 2 and 3. Substrate holding mechanism 14
Has a substrate holder 15. The upper surface and the lower surface of the substrate holder 15 in the figure respectively face the respective electrodes 7 of the plasma generating mechanisms 2 and 3. The substrates 16 and 17 are attached to the upper surface and the lower surface of the substrate holder 15, respectively.
Power is supplied to the substrate holder 15 from an external power supply 18. The substrate holding mechanism 14 includes a substrate 16 and a substrate 17.
It is desirable to have a structure that also serves as a gate valve so that the vacuum container 1 can be sealed when it is installed between both electrodes 7 during the desorption. In this case, the substrate can be attached / detached and exchanged in a load lock chamber (not shown) in a vacuum, and the vacuum container 1 can be constantly kept in a vacuum.

According to the above construction, the electrodes 7 and 7 facing each other are arranged, and the substrates 16 and 17 are provided on both side surfaces of the substrate holder 15.
By holding, it is possible to process two substrates at a time. Also, each magnetic circuit 1 of the plasma generating mechanisms 2 and 3
Since the arrangement of 0's is symmetrical, the magnetic field strength in the discharge space in the front space of each substrate decays quickly, so that each electrode required to make the plasma that diffuses freely becomes uniform. Distance from. As a result, even if the distance between each substrate and the electrode is narrowed, the substrate 1
Plasma with high density and good uniformity can be generated in the front spaces 6 and 17. Therefore, the substrate processing time can be shortened. Furthermore, since the distance between the electrode and the substrate can be narrowed, the size of the entire microwave discharge reactor can be made small, compact, and inexpensive.

In the above embodiment, as a microwave supply method, one microwave power supply mechanism is used and the supply line is branched into two, so that one controller simultaneously supplies the microwaves to the two electrodes. It can also be powered. Further, in the above-mentioned embodiment, the two plasma generating mechanisms 2 and 3 are set as one set, and the one set of plasma generating mechanisms is provided in a predetermined arrangement relationship, but it is optional depending on the size of the vacuum container and the configuration of the apparatus. A set of plasma generation mechanisms can be provided.

[0024]

As is apparent from the above description, according to the present invention, two plasma generating mechanisms are provided in one discharge reaction chamber to process two substrates at the same time. Can be increased. Further, since the electrodes for generating plasma are symmetrically arranged, it is possible to perform the substrate processing with high plasma density and good uniformity at narrow intervals. Therefore, a small, compact, and inexpensive device can be manufactured, and a substrate having a large area can be efficiently processed, which is very practical.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an internal configuration of a microwave discharge reaction device according to the present invention.

FIG. 2 is a front view showing an example of a flat electrode.

[Explanation of symbols]

 1 Vacuum Container 2, 3 Plasma Generation Mechanism 4 Exhaust System 7 Plate Electrode 9 Coaxial Line 10 Magnetic Circuit 12 Microwave Power Supply Mechanism 14 Substrate Holding Mechanism 15 Substrate Holder 16, 17 Substrate

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[Procedure amendment]

[Submission date] November 6, 1992

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Fig. 2]

[Figure 1]

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location H01L 21/31 C H05H 1/46 9014-2G

Claims (2)

[Claims] 1. A vacuum container provided with a mechanism for maintaining a reduced pressure inside and a mechanism for introducing gas, and a slit having a predetermined length and width for radiating a microwave supplied by a coaxial line into the vacuum container. One plate-shaped electrode and a concentric position sharing the center with the electrode, the magnetic field direction being arranged in the vicinity of the electrode so as to be perpendicular to the surface of the electrode, A plurality of cylindrical magnetic field generating means for generating a magnetic field in the same direction as the length direction is provided, and a plasma generating mechanism is configured by a combination of the electrodes and the magnetic field generating means, and two plasma generating mechanisms are set as one set. As at least one set of plasma generating mechanisms are arranged so that the respective electrodes face each other, and a substrate holding mechanism is arranged in the middle of the respective electrodes, before facing the respective electrodes. A microwave discharge reaction device, wherein a substrate is held on each surface of the substrate holding mechanism, and plasma is generated in a space surrounding each surface. 2. The microwave discharge reaction device according to claim 1, wherein each of the magnetic field generating means of the plasma generation mechanism has magnetic poles facing each other, and the magnetic poles facing each other have the same magnetic pole. Microwave discharge reactor.