JPH0578849A - High magnetic field microwave plasma treating device - Google Patents

Abstract

PURPOSE:To provide a high magnetic field microwave plasma treating device which is capable of stably maintaining ECR discharge even when microwave electric power is large and also of reducing the gradient of RF current impressed to control energy of ions and, furthermore capable of lowering constraint based on wavelength of microwave and performing uniform treatment of large area in the device wherein microwave is introduced from the high magnetic field side and the electron cyclotron resonance conditions are realized in the inside of a vacuum vessel to perform plasma treatment. CONSTITUTION:A waveguide 8 for introducing microwave into a vacuum vessel 1 is formed into a flat angular cylinder and arranged in the high magnetic field side. Moreover, an electric conductor 9 described below is provided in the outlet side of the aperture 18a of this waveguide 8. The electric conductor 9 is formed of a plate opposed to a sample 4 and has a through-hole 9a passing microwave in one part thereof. The objective high magnetic field microwave plasma treating device is constituted so that RF current is allowed to flow in the direction of the electric conductor 9, namely in the direction parallel to the magnetic field even when RF current is impressed to the sample 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses CVs generated by microwaves with magnetic field to generate CVs.
The present invention relates to a magnetic field microwave plasma processing apparatus that performs plasma processing such as D (Chemical Vapor Deposition), etching, and sputtering.

[0002]

2. Description of the Related Art In a magnetic field microwave plasma processing apparatus, ionization is carried out by the interaction between a magnetic field and an electric field, and the energy of the electric field is absorbed only by the electrons, so that the energy for the ionization does not directly accelerate the ions. , The incident energy of ions can be lowered. Therefore, when a sample such as a wafer is electrically insulated from a vacuum container, low-energy (tens of eV) ions accelerated by only the sheath voltage generated in the sheath portion of the sample due to the difference in moving speed of electrons and ions. Can be obtained. Further, even when an RF bias is applied to a wafer, it is possible to perform processing without damaging the base with a minimum amount of incident ion energy in which the incident energy of ions is uniform, and therefore, attention has been paid in recent years.

On the other hand, in the plasma processing of an integrated circuit or the like, in which the diameter of a wafer is being increased for higher integration, high-density plasma is uniformly confined over a large area.
It is necessary to dispose a sample in this high-density plasma and perform uniform treatment with radicals generated by an ion flow whose directionality is controlled or plasma. In the case where the reaction is dominated by the reaction of ions, which are charged particles having a relatively short life in the plasma, the sample is processed in the vicinity of ECR plasma having a high ion density in order to improve the processing speed. In the case of performing isotropic processing, it is required to perform processing away from the ECR plasma in order to reduce the ion density and to carry out the reaction mainly of radicals. For example, in the case of CVD processing, it is required to uniformly confine high-density plasma over a large area and to form a film in a desired shape without damaging the underlayer by the ions or radicals in this high-density plasma. Further, for example, in the case of the sputtering process, the high-density plasma is uniformly confined over a large area, the target is sputtered by the ions in this high-density plasma, and the target material is reattached to the sample according to the purpose and sputtered. It is required that the positions be uniform, or that the sample be placed in this high-density plasma to perform uniform sputter etching. Further, for example, in the case of etching treatment, high-density plasma is uniformly confined over a large area, and the base is damaged by ions whose directionality is controlled or radicals generated by plasma in the confined high-density plasma. Instead, it is required to form a film in a desired shape. Generally, in a uniform magnetic field, highly anisotropic treatment can be performed by a controlled direction ion flow, and in a divergent magnetic field, the direction of the ions is disturbed, and radicals generated by plasma mainly react. A highly anisotropic process can be performed, and the etching shape can be continuously changed depending on the position of the sample.

As described above, when a sample such as a large-area wafer is to be processed with high quality, the high-density plasma is uniformly confined over a large area, and the sample is placed near the confined high-density plasma. Therefore, it is necessary to perform uniform treatment with radicals generated by ion flow or plasma whose directionality is controlled. Then, in order to perform such processing, for example, as in the plasma device disclosed in Japanese Patent Laid-Open No. 53-96398, microwaves are introduced into the vacuum container from the high magnetic field side of the magnetic field created by the magnetic field coil. The configuration to be introduced is considered advantageous. In the conventional plasma device of this example, an electromagnetic wave (microwave) synchronized with the angular frequency of electrons that are circularly moving (cyclotron motion) at a constant angular frequency in a plane perpendicular to the magnetic field lines by the magnetic field created by the air-core coil is used. Wave) is introduced into the vacuum vessel from the high magnetic field side to form a magnetic field microwave plasma (ECR plasma) by the excited electrons, and ions of high ion density can be directly used for processing, and RF Since high-speed processing can be performed without accelerating the ions due to the self-bias voltage applied, high-speed and low-damage processing can be performed.

[0005]

The plasma in the magnetic field is
As shown in FIG. 8 which is a schematic explanatory view of the electron (42)
Is strongly bound to the magnetic force line (41), and while moving itself along the magnetic force line (41) while performing cyclotron motion around the magnetic force line (41), the mobility is high in the direction parallel to the magnetic force line (41). However, the mobility in the direction orthogonal to this becomes small. Therefore, the movement of the electrons (82) in the direction orthogonal to the magnetic force lines (41) is reduced. In FIG. 8, (43) is an ion and (44) is a neutral particle. Further, in the divergent magnetic field formed by the magnetic field coil, as shown in the schematic explanatory view [Fig. 9], the magnetic field lines (51) diverge gently, and a high magnetic field remains on the sample (wafer) surface. ing. Thus, while traveling along the diverging magnetic field, the ions (53)
(53) Since it moves to neutralize the charge heterogeneity caused by the higher mobility electron (52), it behaves as if chasing the electron (52) moving along the magnetic field line (51). However, there is a problem that the directionality is disturbed and anisotropic processing cannot be performed. In addition, in [FIG. 9],
(54) is a neutral particle.

However, in a device of the type that introduces microwaves into the vacuum chamber from the high magnetic field side like the above-mentioned conventional plasma device, normally, as shown in the explanatory view (FIG. 10), Since it is introduced from the cylindrical waveguide (64) through the insulator such as quartz glass (63) into the vacuum vessel (61), the RF current (I) is in the direction orthogonal to the magnetic field line (B). Flowing. And, as described above, in the direction orthogonal to the magnetic field, the mobility of electrons becomes small, so that the resistance becomes high with respect to the RF current (I), and the gradient of the RF electric field is formed to treat the sample (65). Is non-uniform. Also,
Even if RF is not applied, microwave wavelength is more than 10 cm
Since the size is about the same as the sample (wafer), there is a problem that the processing becomes non-uniform. In addition, [Fig. 1
0], (62) is an electrode, (67) is an air-core coil, and (67) is an RF power supply. As described above, in the conventional plasma device in which microwaves are introduced into the vacuum chamber from the high magnetic field side, although high-speed and low-damage processing can be performed with ions having a high ion density, RF is used to control ion energy. When applied, an RF current flows in a direction orthogonal to the magnetic force lines, so that a gradient of the RF electric field is generated, resulting in non-uniform processing of the sample (wafer).

The present invention has been made to solve the above-mentioned problems of the prior art, and can stably maintain the ECR discharge even when the microwave power is large, and
To provide a magnetic field microwave plasma processing apparatus capable of reducing the gradient of an RF electric field applied to control the energy of ions and further reducing restrictions due to the wavelength of microwaves, and capable of performing uniform processing of a large area. The purpose is.

[0008]

In order to achieve the above object, the present invention has the following constitution. That is, the magnetic field microwave plasma processing apparatus according to the present invention forms a magnetic field such that the processing gas is introduced into the inside of the vacuum container and the sample container in the vacuum container and the magnetic field lines perpendicularly intersect the sample surface in the vacuum container. The electronic cycloton comprises a magnetic field generating means and a microwave introducing means having a waveguide for introducing microwaves into the vacuum vessel from the high magnetic field side of the magnetic field formed by the magnetic field generating means. In a magnetic field microwave plasma processing apparatus that performs plasma processing such as etching, sputtering, and CVD on a sample by establishing a resonance condition and converting the processing gas into plasma,
On the exit side of the waveguide of the microwave introducing means for introducing the microwave into the vacuum container, a plate-like member facing the sample is formed, and a through hole or an insulating material replacing portion through which the microwave passes is provided in a part thereof. It is characterized in that a conductor is provided.

[0009]

In the apparatus of the present invention, the microwave is vacuumed from the magnetic field generating means for forming the magnetic field so that the magnetic field lines intersect perpendicularly to the sample surface in the vacuum container and the high magnetic field side of the magnetic field formed by the magnetic field generating means. Since the microwave introduction means having a waveguide to be introduced into the container is provided, a microwave (electromagnetic wave) is introduced in the same direction as the magnetic lines of force by the magnetic field generated by the magnetic field generation means, and the excited electrons are generated. Thus, magnetic field microwave plasma (ECR plasma) is formed, and plasma processing can be performed in the vicinity of the place where this ECR plasma is generated. Moreover, since the ions generated in the formed ECR plasma reach the processing target site within a short time,
For example, as in the case of introducing microwaves into the vacuum chamber from the low magnetic field side, electrons and ions may collide and recombine during movement, causing the ions to disappear, or the plasma to be diluted by diffusion. However, ions having a high ion density can be directly used for processing, and high-speed processing can be performed without accelerating the ions due to the self-bias voltage generated by application of RF, so high-speed and low-damage processing can be performed. Also, from the high magnetic field side of the magnetic field formed by the magnetic field generating means,
A conductive material having a through hole or an insulating material replacement portion formed in a plate shape facing the sample on the exit side of the waveguide of the microwave introducing means for introducing the microwave into the vacuum container. Since the body is arranged, while microwaves are introduced into the vacuum container to form ECR plasma,
An RF current generated by RF application for controlling ion energy is made to flow toward a conductor arranged opposite to the sample, that is, in a direction parallel to the magnetic lines of force, and the gradient of the RF electric field is suppressed to be small. As a result, a large-diameter processed product can be uniformly processed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a magnetic field microwave plasma processing apparatus according to the present invention will be described below with reference to the schematic explanatory views [FIG. 1] to [FIG. 7].

FIG. 1 is a schematic explanatory view of a plasma processing apparatus according to a first embodiment of the present invention, in which (a) is a front sectional view of essential parts, and (b) is A in FIG. FIG. In FIG. 1, (1) is a vacuum vessel, and this vacuum vessel (1)
Is the gas inlet (1a) for introducing the processing gas to the side wall and the exhaust port
A disk-shaped quartz plate (2) that allows microwaves to pass through is placed on the upper part of the cylindrical body with (1b) and a disk-shaped electrode ( 3) is arranged to form a pressure vessel, and the inside of the vessel can be evacuated by a vacuum deaerator (not shown).

The electrode (3) is electrically insulated from the main body of the vacuum container (1) by the insulating member (5) being interposed,
This high frequency power supply (6) is connected to the high frequency power supply (6)
RF is applied from. Further, the electrode (3) has a cooling water passage (not shown) provided therein and is connected to a cooling water supply means (not shown) so that the temperature can be controlled.

(7) and (7 ') are a pair of permanent magnets, and the permanent magnets (7), (7') of the pair are disc-shaped with magnetic poles on the upper and lower surfaces, and have different magnetic poles. Parallel to each other in parallel with each other, above and below the vacuum container (1), and the sample (4) inside the vacuum container (1) is placed.
The magnetic field is formed so that the lines of magnetic force intersect perpendicularly to the surface of.

(8) is a waveguide, and this waveguide (8)
Is formed in the shape of a flat rectangular tube and is located on the quartz plate (2) between the upper permanent magnet (7) and the microwave (electromagnetic wave) from the microwave power source (not shown). , Permanent magnets (7)
And is introduced into the vacuum container (1) through a quartz plate (2) from a rectangular opening (8a) provided on the lower surface of the tip of the so-called slot antenna.

(9) is a conductor, and this conductor (9)
Is shaped like a flat disk that covers the lower surface of the quartz plate (2), is located directly below the quartz plate (2), and is a vacuum container.
It is disposed so as to be electrically connected to (1). The conductor (9) has a central portion corresponding to the position of the opening (8a) of the waveguide (8), in order to pass the microwave introduced from the opening (8a), the opening (8a) ) Same rectangular through hole (9a)
Is provided.

In the plasma device of this embodiment having the above structure,
Place the sample (4) on the electrode (3) and place it in the vacuum container (1).
After introducing chlorine gas as a processing gas from (1a), an electric field is supplied by applying RF to the electrode (3) by the high frequency power source (6), and at the same time, microwaves are supplied via the waveguide (8). 875Gau added by pair of permanent magnets (7), (7 ')
The ECR condition is formed on the sample (4) by the interaction with the magnetic field of ss, and the processing gas is turned into plasma, and the permanent magnets of the pair (7),
Plasma treatment such as CVD, etching, and sputtering is performed by the ions and radicals in the uniform plasma that is confined by the magnetic field formed by (7 ′).

By the way, the TE ₁₀ which is generally used
In the mode rectangular waveguide, when a microwave M is introduced as shown in (a) of FIG.
(b) As shown in the figure, the surface current S flowing on the inner surface of the waveguide
Then, a magnetic force line B orthogonal to the current S is generated. Therefore, in the rectangular waveguide, there is a limit in reducing the dimension w in the width direction, and it cannot be shorter than the cutoff wavelength (the length used industrially is 95 mm). On the other hand, on the other hand, the dimension t in the thickness direction is such that the strength of the electric field E generated between the opposing inner surfaces of this waveguide is
It can be shortened until the discharge start voltage in air is reached. Also,
Since the microwave power used for general plasma processing is at most several kW, the dimension t in the thickness direction can be shortened to about 1 cm. Further, even if the dimension w in the width direction is shorter than the cutoff wavelength, microwaves can be propagated if the distance is short. And when a hole is made in a part of the waveguide formed in such a flat rectangular tube shape, it is blocked by this hole, and between the blocked ends is shown in (d) and (e). Thus, the electric field E'is generated. Also, the generated electric field E '
Can change its direction in synchronism with the cycle of the microwave, so that the microwave can be radiated like a dipole antenna. Therefore, the flat rectangular tubular waveguide
In the plasma device of the present embodiment using (8), this waveguide
Even if (8) is arranged between the permanent magnet (7) and the quartz plate (2), the ECR condition can still be satisfied in the vacuum container (1).

Further, in the plasma device of this embodiment, the sample
Conductor (9) is placed on the upper part facing (4), and the parts other than through hole (9a) for introducing microwave have conductivity, so when applying RF to sample (4) However, as in the conventional device shown in (b) of FIG. 3 which is an explanatory view thereof, it is possible to suppress the flow of the RF current (I) in the direction perpendicular to the magnetic field lines (B). As shown in, the RF current (I) can easily flow in the direction toward the conductor (9), that is, in the direction parallel to the magnetic field lines (G), and thus the RF current (I) can flow in the direction parallel to the magnetic field. You can As described above, since the electron mobility is high and the resistance is low in the direction parallel to the magnetic field,
The distribution of the electric field is small, the plasma (P) is stable, and a large area can be uniformly processed.

Next, a second embodiment of the present invention will be described with reference to FIG. [FIG. 4] is a schematic explanatory view of a plasma processing apparatus according to a second embodiment of the present invention, in which (a) is a front sectional view of a main part and (b) is AA of (a). FIG. It is to be noted that the parts denoted by the same reference numerals in FIG. 1 and FIG. 1 are substantially equivalent, and therefore the description thereof will be omitted here.
In this embodiment, two flat rectangular tube-shaped waveguides (8) and (8 ') having the same structure as the example shown in FIG. 1 are connected to the upper permanent magnet (7) and the quartz plate (2). Between the two waveguides (8), on the conductor (9) below the quartz plate (2).
(8 ') Two rectangular through holes (9a), (9b) corresponding to the respective openings (8a), (8a') are provided.

In the plasma device of this embodiment having the above structure,
By introducing the microwaves from the plurality of microwave power sources by the two waveguides, the electric field distribution in the vacuum container can be made more uniform regardless of the wavelength of the microwaves. In this embodiment, two waveguides are arranged so as to face each other, but two or more waveguides are similarly arranged so as to face each other.
It is also possible to introduce microwaves from more than one microwave power source.

Next, a third embodiment of the present invention will be described with reference to FIG. [FIG. 5] is a schematic explanatory view of a plasma processing apparatus according to a third embodiment of the present invention, in which (a) is a sectional view of a main part and (b) is AA in (a). FIG. It is to be noted that the parts denoted by the same reference numerals in FIG. 1 and FIG. 1 are substantially equivalent, and therefore the description thereof will be omitted here.
In this embodiment, a circular opening (18a), a so-called round-hole antenna, is provided on the lower surface of the tip of the flat rectangular tube-shaped waveguide (18), while a conductor (below the quartz plate (2)) is provided. 19) is formed in a mesh shape.

In the plasma device of this embodiment having the above structure,
It is possible to reduce restrictions due to the wavelength of the microwaves due to mutual interference of the introduced microwaves or the like.

Next, a fourth embodiment of the present invention will be described with reference to FIG. [FIG. 6] is a schematic explanatory view of a plasma processing apparatus according to a fourth embodiment of the present invention, in which (a) is a sectional view of a main part and (b) is AA of (a). FIG. It is to be noted that the parts denoted by the same reference numerals in FIG. 1 and FIG. 1 are substantially equivalent, and therefore the description thereof will be omitted here.
In this embodiment, two rectangular quartz plates (22) that allow microwaves to pass through are embedded in the center of the disk-shaped conductor (29), and these are integrated, and then the vacuum container ( The upper part of 1) is airtightly closed, and the conductor (29) is directly connected to the flat rectangular tube-shaped waveguide (28).

In the plasma device of this embodiment having the above structure,
With the simplified configuration, it is possible to obtain the same effect as that of the example shown in FIG. In the present embodiment, two rectangular quartz plates (22) are embedded in the conductor (29) which plays the role of the upper lid, but the number and shape are selected according to its use and purpose. For example, a round shape may be used, and the number may be one or two or more.

In the first to fourth embodiments described above, in order to form a magnetic field so that magnetic lines of force intersect perpendicularly to the surface of the sample (4), a pair of permanent magnets (7), (7 ') The vacuum vessel
Although the magnets are arranged above and below (1), this magnet may be only the permanent magnet (7) on the microwave introduction side, and as in the fifth embodiment shown in FIG. A magnetic field can also be created. [FIG. 7] is a schematic explanatory view of a plasma processing apparatus of a fifth embodiment of the present invention, in which (a) is a front sectional view of a main part and (b) is AA of (a). FIG. It is to be noted that the components denoted by the same reference numerals in FIG. 4 and [FIG. 4] are substantially equivalent, and therefore description thereof will be omitted here.

In the present embodiment, the air-core coils (37), (3) are provided on the upper part of the vacuum container (1) and on the outer side surrounding the vacuum container (1).
7 ') are arranged, and a magnetic field is formed by the upper and lower air-core coils (37), (37') so that magnetic lines of force intersect perpendicularly to the surface of the sample (4). In the plasma device of this embodiment shown in FIG. 7, the arrangement of the waveguide and the conductor is the same as that of the example of FIG. 4, but the arrangement of the waveguide and the conductor is as follows. The same configurations as those of the above-described first and third to fourth embodiments can be adopted. Also, the lower air core coil (37 ') can be omitted.

[0027]

As described above, in the magnetic field microwave plasma processing apparatus according to the present invention, a through hole or an insulating material replacement portion for passing microwaves is provided on the exit side of the waveguide for introducing the microwaves. With a structure that is extremely easy to implement by arranging a conductor having an RF electric field, it is possible to stably maintain an ECR discharge even when the microwave power is large and to apply an RF electric field to control the energy of ions. Can be made smaller and the restriction due to the wavelength of the microwave can be alleviated, and a large effect that uniform processing of a large area can be performed can be obtained.

[Brief description of drawings]

1A and 1B are schematic explanatory views of a plasma processing apparatus according to a first embodiment of the present invention, in which FIG. 1A is a front sectional view of a main part, and FIG.
(a) It is an AA sectional view of a figure.

FIG. 2 is a schematic explanatory view of a waveguide according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram of a flow direction with respect to magnetic force lines of an RF current according to the first embodiment of the present invention.

4A and 4B are schematic explanatory views of a plasma processing apparatus according to a second embodiment of the present invention, in which FIG. 4A is a sectional view of a main part and FIG.
(a) It is an AA sectional view of a figure.

5A and 5B are schematic explanatory views of a plasma processing apparatus according to a third embodiment of the present invention, in which FIG. 5A is a front sectional view of a main part, and FIG.
(a) It is an AA sectional view of a figure.

6A and 6B are schematic explanatory views of a plasma processing apparatus according to a fourth embodiment of the present invention, in which FIG. 6A is a front sectional view of a main part, and FIG.
(a) It is an AA sectional view of a figure.

7A and 7B are schematic explanatory views of a plasma processing apparatus according to a fifth embodiment of the present invention, in which FIG. 7A is a sectional view of a main part and FIG.
(a) It is an AA sectional view of a figure.

FIG. 8 is a schematic explanatory diagram of plasma behavior in a magnetic field.

FIG. 9 is a schematic explanatory diagram of plasma behavior in a divergent magnetic field.

FIG. 10 is an explanatory diagram of a conventional plasma device configured to introduce microwaves into a vacuum chamber from the high magnetic field side.

[Explanation of symbols]

 (1) --Vacuum container (1a) --Gas inlet (1b) --Exhaust port (2) --Quartz plate (3) --Electrode (4) --Sample (5) --Insulating member (6 ) --High frequency power supply (7) --Permanent magnet (7 ')-Permanent magnet (8) --Waveguide (8a)-Aperture (9) --Conductor (9a)-Through hole

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H05H 1/46 9014-2G // H01L 21/31 C 8518-4M

Claims (1)

[Claims] 1. A vacuum container for introducing a processing gas therein and containing a sample, a magnetic field generating means for forming a magnetic field so that magnetic lines of force intersect perpendicularly to a sample surface in the vacuum container, and the magnetic field generating means. From the high magnetic field side of the magnetic field to be formed,
A microwave introducing unit having a waveguide for introducing a microwave into the vacuum container, and by making the processing gas into plasma by establishing electron cycloton resonance conditions in the vacuum container, etching the sample, Sputtering, C
In a magnetic field microwave plasma processing apparatus for performing plasma processing such as VD, a microwave is introduced into a vacuum container on the exit side of a waveguide of a microwave introducing means, which is formed in a plate shape facing the sample. Magnetic field microwave plasma processing apparatus characterized in that a conductor having a through hole or an insulating material replacement portion for passing microwaves is disposed