JP3088504B2 - Microwave discharge reactor - Google Patents

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, Japanese Patent Application Laid-Open No. 55-141729.
(Electron Cyclotron Resonance) disclosed in Japanese Patent Publication
Various devices have been proposed for a discharge reaction device using an electromagnetic wave in a microwave region, such as a device. Generally, in order to efficiently generate plasma in a discharge chamber in this type of discharge reaction apparatus, it is necessary to design the discharge chamber such that the discharge chamber acts as a resonator with respect to the frequency of the microwave to be used. . Therefore, the size of the discharge chamber is dimensionally limited by the wavelength of the microwave (about 12 cm for a commonly used 2.45 GHz microwave). The plasma becomes non-uniform due to the generation of standing waves and the like, and it is impossible to process a substrate having a large area with good uniformity.

On the other hand, the size of a substrate to be processed has been increasing in recent years, and it has become necessary to process a substrate having a size several times the wavelength of a microwave of 2.45 GHz with good uniformity. Further, a conventional discharge reaction apparatus generally employs a structure in which microwaves are introduced into a discharge chamber using a waveguide. Since the size of the waveguide is determined depending on the frequency region to be used, dimensional restrictions in the design of the device are large, and the reliability of the window for introducing microwave is not sufficient.

On the other hand, a coaxial tube has been introduced for introducing microwaves, and a cylindrical electrode having a large number of slits has been used as an antenna for radiating microwaves. Equipment is also being developed.
This device is, for example, A.Yonesu etal. Production of a larg
e-diameter uniform ECR plasma with a Lisitanocoil "
Jpn. J. Appl. Phys., 27 (1988) L1746.). Also, as disclosed in JP-A-1-15997,
Attempts have been made to uniformly treat a large area by using a plate-like electrode having a large number of slits as an antenna.

By the way, in order to generate plasma with good uniformity over a large area using a cylinder having a large number of slits as an electrode, an EC must be formed in the entire cylinder in the cylinder.
For the R condition, that is, for a microwave of 2.45 GHz, it is necessary to generate a magnetic field having a magnetic flux density of 875 gauss in a direction parallel to the slit. For example, in order to process a substrate having a diameter of 300 mm with good uniformity, the above-mentioned A. Yonesu et al. According to the reference, 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 inside such a large electrode with good uniformity, a huge air-core coil is required, which poses a serious obstacle in putting a discharge reactor using the cylindrical electrode into practical use. Had become.

In the discharge reactor disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 1-159397, in which a flat electrode having a large number of slits is used as an antenna, a large space is generated to generate a magnetic field perpendicular to the electrodes. A core coil is required, and the conventional configuration that does not use such an air core coil does not provide good plasma generation efficiency.

Further, a drawback common to the above three types of conventional apparatuses is that the magnetic field used for generating plasma is continuous up to the area where the substrate to be processed is installed. The non-uniformity of the plasma density due to the condition and the standing wave is directly reflected in the distribution of the ion current density on the substrate to be processed, which is an obstacle to performing a uniform processing. In addition, since the trajectory of ions incident on the substrate follows the direction of the magnetic field, the uniformity of the magnetic flux density over the entire surface of the substrate is particularly large 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. This state is generally impossible with a single air-core coil, and the configuration of a micromagnetic discharge reactor becomes very complicated. 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]

In order to solve the above-mentioned problems, the present applicant has previously filed an application for a microwave discharge reaction chamber for solving the 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 can be manufactured in a small configuration at a low cost with a simple configuration in the sense that the coil is not required. It is produced and has good production efficiency, and can perform a uniform treatment on a substrate having a large area, and is extremely practical.

By the way, while the substrate processing has been miniaturized, the ratio of the manufacturing cost to the production cost has recently tended to increase further, and it has been further reduced in size and size, and can process many processing substrates more quickly. There is a demand for a manufacturing apparatus in which the manufacturing cost is kept low.

In view of the above requirements, there is a need for further improvement of the microwave discharge reactor proposed by the present applicant.

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

[0012]

SUMMARY OF THE INVENTION A microwave discharge reactor according to the present invention comprises a vacuum vessel having a mechanism for holding the inside of the reactor at a reduced pressure and a mechanism for introducing a gas, and a microwave supplied by a coaxial line. A plate-like electrode having at least one slit of a predetermined length and width to radiate into the container, and a concentric position sharing the center with the electrode, wherein the magnetic field direction is perpendicular to the electrode. A plurality of ring-shaped magnetic field generating means for generating a magnetic field in the same direction as the length direction of the slit; a plasma generating mechanism comprising a combination of the electrode and the magnetic field generating means;
At least one set of plasma generating mechanisms is provided such that each of the electrodes faces each other, and a substrate holding mechanism is provided in the middle of each electrode, and each of the plasma generating mechanisms faces each of the electrodes. The substrate is held on each surface of the substrate holding mechanism, and plasma is generated in a space around each surface.

In the above-mentioned configuration, preferably, each magnetic field generating means of the plasma generating mechanism has magnetic poles facing each other, and the magnetic poles facing each other have the same polarity.

[0014]

In the microwave discharge reaction device according to the present invention, compared with the device previously proposed by the present applicant, two flat electrodes are used.
And these electrodes are arranged facing each other,
A plasma generation mechanism is configured for each electrode. Further, the two plate-shaped electrodes arranged opposite to each other are arranged at a predetermined interval, and the magnetic field generating means provided for each electrode, that is, the magnetic circuit is arranged such that the positional relationship of the magnetic poles is symmetric. Be placed. As a result, the magnetic field generated by the opposed magnetic poles has a greater attenuation in intensity 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 when the distance between the electrode and the substrate is small, the substrate can be processed with the uniform and high-density plasma. Therefore, the substrate processing speed is increased. Further, since two substrates can be provided in the substrate holding mechanism corresponding to each electrode, the substrate processing ability can be 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 one embodiment of a microwave discharge reaction device according to the present invention. 1 is a vacuum vessel used as a microwave discharge reaction chamber, and the vacuum vessel 1 is actually shown in a cross section. Plasma generating mechanisms 2 and 3 are installed on the upper wall and the lower wall of the vacuum vessel 1 in the drawing.
A vacuum vessel 1 is provided on the left side wall side of the vacuum vessel 1 in the drawing.
An exhaust system 4 for setting the inside of the inside to a required reduced pressure state is installed, and a reactive gas introduction mechanism 6 is provided via a valve 5 on the right side wall side.
Is installed.

The above-mentioned plasma generating mechanisms 2 and 3 are basically composed of the same components. FIG. 2 shows a front view of an electrode portion of each plasma generating mechanism. In each plasma generating mechanism, reference numeral 7 denotes an electrode formed by processing a slit 8 on a flat plate made of a conductive member such as a metal. The overall shape of the electrode 7 is flat and has, for example, a circular shape. The electrode 7 includes an external electrode 7a and an internal electrode 7b located at positions sandwiching the slit 8. In practice, the external electrode 7a and the internal electrode 7b are made from one metal plate. The slit 8 is divided into the following three parts according to its form. 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.
The slits 8b connect the radial slits 8a with a small radius near the center of the electrode and the slits 8c connect with a large radius near the periphery of the electrode. 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, members for assembling the external electrode 7a and the internal electrode 7b are not shown. The width of the slit 8 is actually determined to be an optimum value by an experiment, but needs to be 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 above-mentioned slit 8 is an example, and is not limited to this. In the above description, the respective plate-like electrodes 7 of the two plasma generating mechanisms are arranged at predetermined intervals so as to face each other in parallel.

A coaxial line 9 is used to supply microwaves to the flat electrode 7. In the coaxial line 9, the internal electrode 7
The center conductor 9A is connected to the center of b, and power is supplied by grounding the external electrode 7b. Reference numeral 10 denotes a magnetic circuit including a plurality of cylindrical permanent magnets (including a ring shape). The magnetic circuit 10 is disposed at a slight distance from a 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. Is fixed to one side. The plurality of cylindrical permanent magnets have different diameters and are arranged concentrically. The positions of the N pole and the S pole in each of the permanent magnets are alternately reversed. Note that the configuration shown in FIG. 1 is conceptual,
As a specific coupling structure of the coaxial line 9 and a mounting structure of the magnetic circuit 10, a known arbitrary structure can be adopted. The magnetic poles in the magnetic circuits 10 of the plasma generating mechanisms 2 and 3 are arranged such that the magnetic poles facing each other have the same pole. Reference numeral 12 denotes a microwave power supply mechanism for supplying power to the electrode 7. Also one
3 is disposed between the center conductor 9A and the outer conductor 9B,
It is an insulator for maintaining the degree of vacuum in the vacuum vessel 1.

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

In order to operate the microwave discharge reactor, a predetermined gas is evacuated from the reactive gas introducing mechanism 6 through the valve 5 after the inside of the vacuum vessel 1 is evacuated to a required vacuum state by the exhaust system 4. It is introduced into the container 1. Next, a predetermined gas pressure is obtained by appropriately adjusting the gas flow rate and the exhaust speed by the exhaust system 4. The gas pressure at this time is usually
It is desirable to be about 10 ^-2 to 10 ^-6 Pa. A microwave discharge is generated in the vacuum vessel 1 under such conditions.
A microwave is supplied to the electrode 7 through the coaxial line 9 from a microwave power supply mechanism 12 including a microwave circuit element such as an isolator, a power monitor, and a tuner. The outer conductor 9 </ b> B of the coaxial line 9 penetrates the upper wall of the vacuum vessel 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 inner space of the vacuum vessel 1 by the operation of the slit 8 to generate a strong oscillating electric field. The reactive gas introduced into the vacuum vessel 1 is ionized by the electrons accelerated by the electric field, and becomes a plasma state. Electrons in the plasma are heated resonantly by the interaction of the electric field with the magnetic field (heating by the ECR effect), and ionize other neutral particles one after another to generate high-density plasma. A discharge reaction is performed using this plasma.

A substrate holding mechanism 14 is disposed 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 drawing face the respective electrodes 7 of the plasma generating mechanisms 2 and 3, respectively. The substrates 16 and 17 are mounted on the upper and lower surfaces 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 functions as a gate valve so that the vacuum vessel 1 can be sealed when it is installed between the two electrodes 7 at the time of desorption. In this case, the substrate can be detached and replaced in a vacuum in a load lock chamber (not shown), and the vacuum vessel 1 can be constantly kept in a vacuum.

According to the above-described structure, the opposed electrodes 7, 7 are provided, and the substrates 16, 17 are provided on both side surfaces of the substrate holder 15.
, Two substrates can be processed at a time. Also, each magnetic circuit 1 of the plasma generating mechanisms 2 and 3
Since the arrangement of 0 is symmetrical, the manner in which the magnetic field intensity in the discharge space in the front space of each substrate is attenuated faster is increased. The distance from is shortened. As a result, even if the distance between each substrate and the electrode is reduced, the substrate 1
It is possible to generate high-density and uniform plasma in the front space 6 and 17. Therefore, the substrate processing time can be reduced. Further, since the distance between the electrode and the substrate can be reduced, the entire size of the microwave discharge reaction device can be made small, compact, and inexpensive.

Further, in the above-mentioned 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 can simultaneously apply microwaves to two electrodes. Power can also be supplied. Further, in the above-described embodiment, the two plasma generating mechanisms 2 and 3 are set as one set, and this one set of plasma generating mechanisms is provided in a predetermined arrangement relationship. A number of plasma generating 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, and two substrates are processed simultaneously, so that the film forming capacity is improved. Can be enhanced. In addition, since the electrodes for generating plasma are arranged symmetrically, substrate processing with high plasma density and good uniformity can be performed at narrow intervals. Therefore, a compact, compact and inexpensive apparatus can be manufactured, and in addition, a substrate having a large area can be efficiently processed, which is very practical.

[Brief description of the 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]

 DESCRIPTION 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

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ identification code FI H05H 1/46 H05H 1/46 M (58) Field surveyed (Int.Cl. ⁷ , DB name) C23F 4/00 C23C 14 / 35 C23C 16/511 H01L 21/205 H01L 21/31 H05H 1/46

Claims (2)

(57) [Claims] 1. A vacuum vessel having a mechanism for keeping the inside in a reduced pressure state and a mechanism for introducing gas, and a slit having a predetermined length and width for radiating microwaves supplied by a coaxial line into the vacuum vessel. A plate-like electrode having one, a concentric position sharing a center with the electrode, and disposed at a position near the electrode such that the magnetic field direction is 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; a plasma generating mechanism comprising a combination of the electrode and the magnetic field generating means; At least one set of plasma generating mechanisms is disposed such that the respective electrodes face each other, and a substrate holding mechanism is disposed in the middle of the respective electrodes. A microwave discharge reaction apparatus, wherein a substrate is held on each surface of the substrate holding mechanism, and plasma is generated in a space around each of the surfaces. 2. The microwave discharge reactor according to claim 1, wherein each of the magnetic field generating means of the plasma generating mechanism has magnetic poles facing each other, and the magnetic poles facing each other have the same polarity. Microwave discharge reactor.