JPH08311668A - High frequency plasma processing equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to adjust the plasma density distribution of a high-frequency plasma processing apparatus, suppress wall deviation, and enable high-speed cleaning of the plasma generation chamber. [Composition] Only in the region near the side wall 31 of the plasma generation chamber 3,
A magnetic field coil 1 having a local magnetic field configuration having a main component in the central axis direction
a and 1b, the magnetic field strength distribution in the plasma 10 is adjusted, thereby adjusting the degree of plasma diffusion in the plasma 10 in the horizontal direction and adjusting the plasma density distribution in the horizontal direction. During discharge cleaning with the cleaning gas, cleaning is accelerated by eliminating the main magnetic field on the wall surface and strengthening the interaction between the gas and the wall. This makes it possible to adjust the plasma density distribution,
It is possible to suppress the generation of foreign matter due to the wall surface deviation to a small extent, and at the same time, to secure the plasma confinement property and to perform high-speed cleaning of the inner wall of the plasma generation chamber.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency plasma processing apparatus for forming a thin film on a substrate or etching processing by using plasma generated by high frequency discharge, and particularly suitable for uniformly processing a large-diameter substrate. Plasma processing apparatus.

[0002]

2. Description of the Related Art A plasma processing apparatus is composed of a plasma processing chamber having an inlet for introducing a raw material gas and an exhaust outlet for evacuating, and an apparatus for supplying electromagnetic energy for generating plasma. There is. In order to uniformly process a large-diameter substrate using such a plasma processing apparatus, it is necessary to generate a uniform plasma over a large area.

As a conventional technique of a high frequency plasma processing apparatus capable of processing such a large area substrate, for example, PLG
Ventzek et al., Appl. Phys. Lett. Vol.63 (5) pp.605
-607 "Two-dimensional hybrid model of inductively c
There is "upled plasma sources for etching".
In this conventional device, a spiral electromagnetic induction coil is arranged on the upper surface of the plasma generation chamber, and a large number of permanent magnets are arranged on the side wall to improve the plasma confinement performance. Is formed.

[0004]

In the conventional plasma processing apparatus shown in FIG. 12 described above, the plasma density distribution changes depending on the degree of vacuum and the high frequency power, so that the plasma processing characteristics on the substrate are made uniform. The degree of vacuum and the value of high frequency power are limited to a certain area. Moreover, since there is no mechanism for adjusting the plasma density distribution, there is a problem that the plasma density distribution cannot be adjusted while the vacuum degree and the high frequency power value are kept constant.

In order to improve the plasma confinement property and further flatten the plasma density distribution, a permanent magnet is installed outside the plasma side wall. Due to this permanent magnet,
When the discharge cleaning is performed with the cleaning gas, the cleaning effect due to the interaction between the plasma generated by the cleaning gas and the entire side wall surface is significantly reduced, which causes a problem that the cleaning speed cannot be increased.

Further, since an electromagnetic induction coil installed near the upper surface of the plasma generating chamber induces a high-frequency high frequency electric field just below the upper wall surface, a high-density plasma is generated immediately below the upper wall surface, and the upper wall surface is displaced, resulting in a plasma. There is also a problem that foreign matter is generated in the generation chamber, and the foreign matter adheres to the substrate as dust, which reduces the yield of substrate processing.

A first object of the present invention is to provide a plasma processing apparatus capable of adjusting the plasma density distribution.

A second object of the present invention is to provide a plasma processing apparatus capable of high-speed cleaning while maintaining good plasma confinement.

A third object of the present invention is to provide a plasma processing apparatus capable of preventing the upper wall surface from being scraped.

[0010]

The first and second objects are to form a local magnetic field having a main component in the central axis direction (perpendicular to the surface of the substrate) only in the outer peripheral portion of the plasma generation chamber. At the same time, it is achieved by providing means for forming a weak magnetic field or no magnetic field inside the plasma generation chamber and means for adjusting the magnetic field strength in the plasma generation chamber.

The above first and second objects can be further achieved by adding a plurality of plasma generating means.

The above third object is achieved by providing a means for forming a local magnetic field substantially parallel to the wall of the plasma generating chamber close to the plasma generating electromagnetic coil and increasing the magnetic field strength closer to the wall. It

[0013]

Function: A local magnetic field having a main component in the central axis direction is formed only in the outer peripheral portion of the plasma generation chamber to secure the plasma confinement property, and a weak magnetic field formed in the plasma generation chamber in the substantially central axis direction. The degree of lateral diffusion of plasma can be adjusted by adjusting the intensity of. Thereby, the lateral density distribution of plasma in the equilibrium state can be adjusted. Further, since such a magnetic field can be formed by the magnetic field coil, the magnetic field disappears when the current flowing through the magnetic field coil is cut off, and the plasma generated by the cleaning gas can effectively interact with the side wall, thereby achieving high-speed cleaning.

Further, a local magnetic field is formed substantially parallel to the wall of the plasma generating chamber adjacent to the plasma generating electromagnetic coil,
If the magnetic field strength is increased closer to the wall, the high electric field near the wall near the electromagnetic coil for plasma generation locally generates plasma at high density.However, since the magnetic field strength is strong near the wall, plasma is generated from the wall. In the equilibrium state, the plasma density near the wall becomes low and the deviation on the wall surface is suppressed.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 is a configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention. In the plasma generation chamber 3 equipped with a substrate holder 51 for mounting the substrate 50, magnetic field coils 1a and 1b of a plurality of systems, for example, two systems inside and outside, are arranged on the outer peripheral portion. Reverse currents are respectively applied to the two upper and lower magnetic field coils 1a and 1b connected to the magnetic field coil power supply 11 and the coil current adjusting device 12. In the present embodiment, the magnetic field coils 1a and 1b form a local magnetic field generating means.

The magnetic field configuration at this time is shown in FIG. As shown in FIG. 2, if the respective current values are made approximately the same, the magnetic fields generated by the magnetic field coils 1a and 1b of the two internal and external systems are
Nearly cancel each other on the inner circumference side of the magnetic field coil 1a,
A weak magnetic field or no magnetic field is formed in the inner space (space on the central axis side) of the coil 1a in the plasma generation chamber 3. On the other hand, 2
In the ring-shaped space sandwiched between the magnetic field coils 1a and 1b of the system, that is, the space along the outer peripheral wall of the plasma generation chamber 3, the magnetic fields of the respective coils 1a and 1b reinforce each other, and therefore, along the central axis of the plasma generation chamber 3. A magnetic field is generated in this ring-shaped space. Further, on the outside of the magnetic field coil 1b, the time by the two coils 1a and 1b cancels each other out to form a weak magnetic field, similarly to the inside. That is, the side wall 31 of the plasma generation chamber 3 sandwiched between the magnetic field coils 1a and 1b.
A strong magnetic field can be locally formed in the region along the line.

This magnetic field distribution is shown in FIGS. Both figures show the radial distribution of the axial magnetic field component inside and outside the plasma generation chamber, and FIG. 3 shows the case of a weak magnetic field.
Indicates the case of no magnetic field. In this magnetic field configuration,
As is clear from the direction of the coil, the magnetic field has the main component in the direction parallel to the central axis in the plasma generation chamber 3. When such a magnetic field configuration is formed, the local magnetic field at the outer periphery secures the plasma confinement property, and then the weak magnetic field strength formed in the plasma generation chamber 3 is adjusted, whereby the plasma in the horizontal direction is adjusted. It is possible to adjust the degree of diffusion of the plasma and the plasma density distribution in the equilibrium state.

Since the maximum magnetic flux density of the local magnetic field on the side wall may be several tens of Gauss or about 100 to 200 Gauss, a strong magnetic field of 875 Gauss as used in a plasma processing apparatus using a microwave of 2.45 GHz is used. There is no need, and the operating cost is almost determined only by the high frequency power, and the operating cost for forming the magnetic field can be ignored.

In this embodiment, the ring-shaped high-frequency electromagnetic induction coil 2 for plasma generation has a plasma generation chamber 3
It is externally fitted to the outer peripheral part of the device and is closely attached to the side wall 31, and is connected to the high frequency power source 21 and the high frequency power adjusting device 22. As a result, as described above, although a high electric field is induced in the vicinity of the side wall 31, the plasma is diffused to the inner peripheral side, so that the plasma density in the vicinity of the side wall 31 is suppressed to be low and the abrasion of the wall is suppressed.

FIG. 5 is a block diagram of a plasma processing apparatus according to the second embodiment of the present invention. In this embodiment, the first
In addition to the configuration of the embodiment, a ring-shaped high-frequency electromagnetic induction coil 2a for plasma generation is installed on the upper surface opposite to the substrate 50 such that its central axis is concentric with the substrate holder 51. Ring-shaped permanent magnets 6a and 6b having upper and lower magnetic poles are arranged on the inner peripheral portion and the outer peripheral portion of the induction coil 2a, respectively. In this case, the polarities of the magnetic poles are opposite to each other. As a result, as shown in FIG. 6, in the upper surface wall near the high frequency electromagnetic induction coil 2a, the magnetic field strength is stronger as it is closer to the wall, and a magnetic field substantially parallel to the wall can be formed, so that deviation of the wall can be suppressed. As described above, by providing the plasma generating means at a plurality of locations, it is possible to adjust the magnetic field strength in the plasma generating chamber and to adjust the plasma density distribution with a higher degree of freedom.

The ring-shaped permanent magnets 6a and 6b are
As shown in FIG. 7, two pairs of 2 having different current directions are used.
The heavy loop coils 61a and 61b may be used instead. In this way, the discharge cleaning with the cleaning gas can reach the entire upper surface by cutting off the electric current of the double loop coils 61a and 61b at the time of cleaning, so that high speed cleaning of the upper surface can be achieved.

FIG. 8 is a block diagram of a plasma processing apparatus according to the third embodiment of the present invention. In the present embodiment, a plurality of (three in the illustrated example) double loop magnetic field coils 62 having mutually different current directions are externally arranged outside the side wall 31 of the plasma generation chamber 3. A magnetic field coil power supply 11 and a coil current adjusting device 12 are connected to each double loop magnetic field coil 62. In this case, the amount of current flowing in each coil of each double loop magnetic field coil 62 is independently changed by using the coil current adjusting device 12, so that no magnetic field is generated in the inner peripheral portion of the plasma generation chamber, and from several Gauss. A weak magnetic field of about a dozen Gauss can be formed. This is not possible with permanent magnets. Furthermore, a small-diameter high-frequency electromagnetic induction coil 41 for plasma generation
A large-diameter high-frequency electromagnetic induction coil 42 is arranged concentrically with the substrate holder 51 on the upper wall of the plasma generation chamber. In this embodiment, permanent magnets are arranged on the inner and outer circumferences of the coils 41 and 42, respectively, as in the embodiment of FIG. Even in this case, the same function as in FIG. 5 can be provided.

It is needless to say that a single high-frequency electromagnetic induction coil may be provided instead of a plurality, and the high-frequency electromagnetic induction coil may be installed at a position on the upper surface or side surface. In this case, the degree of freedom in adjusting the plasma density distribution is reduced, but the configuration is simplified.

FIG. 9 is a block diagram of a plasma processing apparatus according to the fourth embodiment of the present invention. In this embodiment, the high frequency electromagnetic induction coil 2 and the magnetic field coil 1a are integrally formed. The details are shown in FIG. Insulation coating for magnetic field coil 1a
Electromagnetic shield 23 covered with 13 and made of metal plate
Coat with a. Immediately next to it, the high frequency electromagnetic induction coil 2 casing with the electromagnetic shield 23b is installed. By eliminating the electric coupling between the magnetic field coil 1a and the high-frequency electromagnetic induction coil 2 from the electromagnetic shields 23a, 23b, etc., it is possible to provide a structure that functions as an integrated type. According to this embodiment, since the magnetic field coil and the electromagnetic induction coil are integrated,
The whole structure can be made simpler.

The high frequency electromagnetic induction coil shown in the above-mentioned embodiment is required to shield the high frequency in order to prevent the high frequency from leaking to the outside. This high frequency shield will be described with reference to FIG. In order to efficiently send the high frequency waves to the plasma generation chamber 3, the inductance of the high frequency electromagnetic induction coil 2 must be reduced. The reason is that if the inductance is large, the high frequency resistance becomes large, and that extra high frequency power is required. Further, it is necessary to localize the high frequency induction electric field inside the plasma generation chamber 3 in order to enhance the adjusting function of the plasma density distribution. Therefore, in order to reduce the inductance and enhance the locality of the high frequency induction electric field,
As shown in FIG. 11, the number of turns of the high frequency electromagnetic induction coil 2 is reduced and the high frequency shield 23 is brought close to the high frequency electromagnetic induction coil 2. As a result, the high-frequency magnetic field excited by the high-frequency electromagnetic induction coil 2 is confined inside the high-frequency shield 23, and the high-frequency magnetic field leaking from the high-frequency shield 23 into the plasma generation chamber 3 causes the high-frequency electric field to be immediately below the high-frequency electromagnetic induction coil 2. Locally induced.

The magnetic field coil 1 shown in the above embodiment is used.
The currents to be passed through the a, 1b and the double magnetic field coils 61, 62 are assumed to be DC currents, but the function can be achieved by an AC current or a synergistic combination of a DC current and an AC current. Further, as in the first to fourth embodiments, the method of forming the local magnetic field having the main component in the central axis direction along the side wall of the plasma generation chamber is performed by the high-frequency plasma treatment by the high-frequency electromagnetic induction coil. Needless to say, it can be applied not only to the apparatus but also to a general plasma processing apparatus using microwaves.

[0027]

According to the present invention, the plasma density distribution can be adjusted in a state where the plasma confinement property is improved, the plasma generation chamber can be cleaned at high speed, and the wall deviation can be suppressed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a magnetic field configuration of the plasma processing apparatus shown in FIG.

3 is a diagram showing a radial distribution of an axial magnetic field component in a weak magnetic field of the plasma processing apparatus shown in FIG.

FIG. 4 is a diagram showing a radial distribution of an axial magnetic field component in the plasma processing apparatus shown in FIG. 1 without a magnetic field.

FIG. 5 is a configuration diagram of a plasma processing apparatus according to a second embodiment of the present invention.

6 is a diagram showing a magnetic field configuration in the plasma processing apparatus shown in FIG.

FIG. 7 is a diagram showing a modification of the second embodiment of the present invention.

FIG. 8 is a configuration diagram of a plasma processing apparatus according to a third embodiment of the present invention.

FIG. 9 is a configuration diagram of a plasma processing apparatus according to a fourth embodiment of the present invention.

FIG. 10 is a parts diagram of the fourth embodiment of the present invention.

FIG. 11 is a diagram illustrating a high frequency shield.

FIG. 12 is a diagram showing a typical conventional example.

[Explanation of symbols]

1 ... magnetic field coil, 2, 41, 42 ... high frequency induction electromagnetic coil,
3 ... Plasma generation chamber, 6 ... Permanent magnet, 11 ... Magnetic field coil power supply, 12 ... Coil current adjusting device, 13 ... Insulation coating, 21 ... High frequency power supply, 22 ... High frequency power adjusting device, 23 ... High frequency shield, 10 ... Plasma, 31 ... Side wall, 50 ... Substrate, 51 ... Substrate holder, 61, 62 ... Double loop magnetic field coil.

Claims (10)

[Claims] 1. A plasma generation chamber which is composed of a metal wall and an insulator wall and into which a discharge gas is introduced, and a plasma generation chamber which is arranged near the insulator wall outside the plasma generation chamber and induces a high-frequency electric field in the plasma generation chamber. In a high-frequency plasma apparatus comprising a plasma generating means for generating plasma and a substrate holder placed in the plasma generating chamber for placing a substrate to be plasma-processed, the surface of the substrate is provided only in the space near the peripheral wall surface in the plasma generating chamber. A high-frequency plasma processing apparatus characterized in that it is provided with a local magnetic field generating means for forming a local magnetic field having a main component in a direction perpendicular to the above. 2. The high frequency plasma processing apparatus according to claim 1, wherein the local magnetic field generating means is at least one pair of magnetic field coils having different current directions. 3. The high frequency plasma processing apparatus according to claim 2, wherein at least one pair of magnetic field coils having different current directions are arranged on the upper wall, the lower wall or the side wall of the plasma generation chamber. 4. The high frequency plasma processing apparatus according to claim 1, further comprising a plurality of plasma generating means. 5. The high frequency plasma processing apparatus according to claim 4, wherein a magnetic field generating means is provided in the vicinity of the plasma generating means, and the magnetic field generating means forms a magnetic field substantially parallel to the wall of the plasma generating chamber. 6. The high frequency plasma processing apparatus according to claim 4, wherein the plasma generating means is formed by a coil and the magnetic field generating means is formed by a coil, and both coils are integrated. 7. A plasma generation chamber which is composed of a metal wall and an insulator wall and into which a discharge gas is introduced, and a plasma generation chamber which is arranged near the insulator wall outside the plasma generation chamber and induces a high-frequency electric field in the plasma generation chamber. In a high-frequency plasma apparatus comprising a plasma generating means for generating plasma and a substrate holder placed in the plasma generating chamber for mounting a substrate to be subjected to plasma processing, a multipolar magnetic field is formed only near the inner side wall of the plasma generating chamber, A high-frequency plasma processing apparatus, comprising a plurality of double-loop magnetic field coils arranged on an outer peripheral portion of a side wall of a generation chamber and having different current directions. 8. The local magnetic field according to claim 1, wherein a local magnetic field is formed only in the vicinity of an outer peripheral wall of the plasma generation chamber when the substrate is plasma-processed, and the local magnetic field is not formed when the plasma chamber is discharge-cleaned with a cleaning gas. A high frequency plasma processing apparatus comprising a control means. 9. A metal high-frequency shield wall for shielding a high frequency generated by a high-frequency electromagnetic induction coil as a plasma generating means to the outside of the apparatus according to claim 1, A high-frequency plasma processing apparatus, wherein the high-frequency shield wall is provided close to a high-frequency electromagnetic induction coil. 10. A plasma generation chamber configured by a metal wall and an insulator wall into which a discharge gas is introduced, plasma generation means for introducing microwaves into the plasma generation chamber to generate plasma, and the plasma generation. In a high-frequency plasma apparatus provided with a substrate holder placed in a chamber for mounting a substrate to be subjected to plasma processing, means for forming a local magnetic field having a main component in a direction perpendicular to a surface of the substrate only in the vicinity of a peripheral wall surface in the plasma generation chamber. A high-frequency plasma processing apparatus comprising: