JPH09171900A - Plasma generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To minimize a plasma loss and improve active seed density by exciting a medium gas within a plasma chamber by a microwave, and extending it to a microwave guide window lower surface and the side and lower surface of dielectrics to generate a plasma. SOLUTION: The microwave generated in a microwave generating circuit is propagated in a microwave guide 4, released through a microwave releasing hole 5, transmitted by a microwave guide window 3, and guided into a plasma chamber 1. This microwave is radially extended from the microwave releasing hole 5, propagated to the surface of dielectrics 30 as a surface wave, and extended to the lower surface of the microwave guide window 3 and the side and lower surfaces of the dielectrics 30. Thus, a medium gas sealed in the plasma chamber 1 is excited by this microwave to generate a plasma extended to the lower surface of the microwave guide window 3 and the side and lower surfaces of the dielectrics 30. Thus, the active seed density of the plasma can be uniformed and increased within a wide area.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generator for a process in which a plasma generation region is improved.

[0002]

2. Description of the Related Art Examples of process plasma devices using microwaves include etching devices and ashing devices. In such a process plasma apparatus, a medium gas is introduced into a reaction container at a pressure of several Pa to several tens Pa, and microwave power is introduced into the reaction container to excite the medium gas into plasma, which is generated by this plasma. In addition, the substrate to be processed, such as a substrate, is etched or ashed by active species such as radicals and ions.

In this process plasma device,
For example, in order to process a large area on a substrate, it is required to generate a uniform plasma over a large area.
FIG. 6 is a block diagram of such a process plasma apparatus.

At the top of the plasma chamber 1 is an opening 2
Are formed. The opening 2 of this plasma chamber 1
Is provided with a plasma wave introduction window 3 and a microwave waveguide 4 for introducing microwaves into the plasma chamber 1.

The microwave waveguide 4 is provided with a microwave emission port 5 at a position corresponding to the opening 2 of the plasma chamber 1 through the plasma wave introduction window 3. A microwave generation circuit (not shown) is connected to the microwave waveguide 4.

The plasma wave introducing window 3 is made of, for example, a dielectric material such as quartz or alumina ceramic in order to efficiently introduce the microwave into the plasma chamber 1.
On the side surface of the plasma chamber 1, for example, O ₂ , CF
A gas supply port 6 for supplying a medium gas such as ₄ into the plasma chamber 1 is provided.

On the other hand, below the plasma chamber 1, a process chamber 7 is connected. A processing stage 8 for mounting a processing target is provided in the process chamber 7, and a gas exhaust port 9 for exhausting gas is provided in the lower portion.

With such a configuration, the microwave generated by the microwave generation circuit propagates through the microwave waveguide 4 and is emitted from the microwave emission port 5, and passes through the plasma wave introduction window 3 to generate plasma. It is introduced into the chamber 1.

The microwave excites the medium gas sealed in the plasma chamber 1 to generate plasma 10. The generation of the plasma 10 produces active species, and the active species are carried by the gas flow toward the exhaust port 9 of the process chamber 7 and process the substrate mounted on the processing stage 8.

Here, the size of the plasma 10 generated by the microwave is smaller than that of the opening 2. this is,
Since the plasma chamber 1 is made of metal, the electric field on the metal surface becomes zero, plasma is not generated on the metal surface, and ions in the plasma generated near the opening 2 are transmitted to the metal surface. By recombining and disappearing.

Since the area where the plasma 10 exists is smaller than the opening 2, the distribution of the density of active species on the surface of the processing stage 8 is high in the central portion as shown in FIG. 6 and around the opening 2. In the part, the loss of the plasma 10 becomes large and becomes low.

Since the density of the active species of the plasma 10 is thus distributed, the processing amount and shape of the workpiece in the process are determined by the density of the active species. The problem of becoming uniform occurs.

In order to avoid this, the region where the process is performed is limited to the region where the active species density does not decrease, that is, the region E within the dotted line shown in FIG. Therefore, the processing range of the process is smaller than the apparatus size, and a large apparatus is required to perform processing in a large area.
Further, the plasma loss on the surface of the opening 2 is large, and the generated plasma cannot be effectively utilized.

On the other hand, as a plasma processing apparatus using microwaves, for example, there is a technique described in Japanese Patent Laid-Open No. 6-104210. FIG. 7 is a block diagram of such a plasma processing apparatus. A processing chamber 23 is provided in the opening of the waveguide 21 provided with the magnetron 20 through a quartz window 22.

A coil 24 is arranged outside the side surface of the processing chamber 23, and a sample table 26 for mounting a sample 25 is provided inside thereof. Also, on the side surface of the processing chamber 23,
A gas pipe 27 is provided.

The quartz window 22 in the processing chamber 23 is provided with a plurality of dielectrics 28 protruding so as to divide the inside of the processing chamber 23. With such a configuration, the microwave generated by the magnetron 20 propagates in the waveguide 21, passes through the quartz window 22, and enters the processing chamber 23.

In this case, each dielectric 28 in the processing chamber 23
Is connected to the quartz window 22 and is arranged in a state of being largely protruded, so that the plasma generated by the microwave is divided, and thereby the plasma density becomes substantially uniform without being significantly attenuated.

However, the existing area of the plasma 10 is not increased, but only the uniformization is achieved in a narrow area. Therefore, a large device is required to perform processing in a large area.

[0019]

As described above, since the region where the plasma 10 exists is smaller than the opening 2, the region where the process is performed is limited to the region where the active species density does not decrease. The processing range of the process is smaller than the device size, and a large device is required to perform processing in a large area. Further, the plasma loss on the surface of the opening 2 is large, and the generated plasma cannot be effectively utilized.

Further, even one of the apparatuses does not increase the area where the plasma 10 exists, a large apparatus is required to perform processing in a large area. Therefore, it is an object of the present invention to provide a plasma generator capable of uniformly increasing the active species density of plasma over a wide area.

[0021]

According to a first aspect of the present invention, a plasma is generated by introducing a microwave into a reaction vessel through a microwave introduction window and exciting a medium gas enclosed in the reaction vessel to generate plasma. In the apparatus, a plasma generator is provided with a dielectric attached to an inner wall of a reaction container at least in the vicinity of a microwave introduction window.

With such a plasma generator, when microwaves are introduced into the reaction container through the microwave introduction window, the microwaves are generated on the inner wall of the reaction container adjacent to the microwave introduction window. Propagating as a surface wave along the surface of the dielectric provided on the substrate, thereby expanding the plasma existing region. Also, because the dielectric is not conductive,
Electrons are not supplied from the surface, recombination is less likely to occur, and plasma loss is extremely small.

According to a second aspect of the present invention, in the plasma generator of the first aspect, a taper portion that widens toward the inside of the reaction vessel is formed at the opening of the reaction vessel connected to the microwave introduction window. A dielectric was attached to a portion including this taper portion.

In such a plasma generator, since the opening of the reaction container is formed in the tapered portion and the dielectric is provided, the plasma existing region is further expanded. According to claim 3, in the plasma generator according to claim 1, a slot antenna is formed in the microwave introduction window.

With such a plasma generator, since microwaves propagate radially from the narrow groove of the slot antenna, the plasma existing region is more likely to spread than the dielectric surface.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION

(1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a plasma generator corresponding to claim 1. An opening 2 is formed in the upper part of the plasma chamber 1. A plasma wave introduction window 3 is provided in the opening 2 of the plasma chamber 1, and a microwave waveguide 4 for introducing a microwave into the plasma chamber 1 is further provided.

In the microwave waveguide 4, the microwave emission port 5 is provided at a position corresponding to the opening 2 of the plasma chamber 1 through the plasma wave introduction window 3. A microwave generation circuit (not shown) is connected to the microwave waveguide 4.

The plasma wave introducing window 3 is made of, for example, a dielectric material such as quartz or alumina ceramic in order to efficiently introduce the microwave into the plasma chamber 1. A dielectric 30 is attached to the inner wall of the plasma chamber 1 adjacent to the plasma wave introduction window 3.

As the material of this dielectric 30, for example, glass, ceramic or the like is used. This dielectric 30
The mounting method may be, for example, any of a screw-fastening method, a fitting method, and an adhesive method. Alternatively, a dielectric such as ceramic may be coated or may be welded by thermal spraying.

It is preferable that the dielectric 30 and the dielectric forming the plasma wave introducing window 3 have the same dielectric constant and the same material. A gas supply port 6 for supplying a medium gas such as O ₂ or CF ₄ into the plasma chamber 1 is provided on the side surface of the plasma chamber 1.

On the other hand, below the plasma chamber 1, a process chamber 7 is connected. A processing stage 8 for mounting a processing target is provided in the process chamber 7, and a gas exhaust port 9 for exhausting gas is provided in the lower portion.

Next, the operation of the device configured as described above will be described. The microwave generated by the microwave generation circuit propagates through the microwave waveguide 4, is emitted from the microwave emission port 5, passes through the plasma wave introduction window 3, and is introduced into the plasma chamber 1.

This microwave spreads radially from the microwave emission port 5 and propagates on the surface of the dielectric 30 as a surface wave. That is, the microwave is transmitted through the microwave introduction window 3
Of the dielectric 30 and the sides and bottoms of the dielectric 30.

Therefore, the medium gas enclosed in the plasma chamber 1 is excited by the microwave, and the medium gas shown in FIG.
As shown in Fig. 3, the lower surface of the microwave introduction window 3 and the dielectric 3
Plasma 31 spreading to the side and the bottom of 0 is generated.

In this case, since the dielectric material 30 is not conductive, electrons are not supplied from its surface, and recombination of these electrons and ions in plasma is unlikely to occur.
Plasma loss is extremely small. That is, the active species density of plasma increases.

The generation of such plasma 30 produces active species, which are carried by the gas flow toward the exhaust port 9 of the process chamber 7 to process the substrate mounted on the processing stage 8. To do.

From the above, the active species density (a) on the upper surface of the processing stage 8 is more uniform in a wider area than the conventional active species density (b) as shown in FIG. The absolute value of the density is also high.

As described above, in the first embodiment, the dielectric 30 is attached to the inner wall of the plasma chamber 1 which is in contact with the microwave introduction window 3, so that the microwave is generated along the surface of the dielectric 30. Propagation as a surface wave makes it possible to make the active species density of the plasma uniform over a wide area and increase the absolute value of the density.
Since 0 has no conductivity, electrons are not supplied from its surface, recombination with ions in plasma is less likely to occur, and plasma loss can be made extremely small.

Therefore, the range suitable for the machining process is shown in FIG.
The area E can be expanded from the conventional area E shown in FIG. In other words, if the processing size is the same, the device itself can be downsized, and the cost of the device can be reduced accordingly.

Furthermore, since the density of active species in the entire region can be increased, the processing speed can be increased. Further, since only the dielectric 30 is attached, it is possible to easily attach the dielectric 30 to an existing plasma generator to make the active species density of plasma uniform over a wide area and increase the absolute value of the density. (2) Next, a second embodiment of the present invention will be described.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 3 is a block diagram of a plasma generator corresponding to the second aspect. Opening 32 of plasma chamber 1
Are formed in a tapered shape (hereinafter referred to as a tapered portion 32) that spreads in a direction from the microwave waveguide 4 to the inside of the plasma chamber 1.

A dielectric 33 is attached to the tapered portion 32 and the inner wall of the plasma chamber 1 which is continuous with the tapered portion 32. As the material of the dielectric 33,
Similarly to the above degree, for example, glass, ceramics, etc. are used, and the mounting method thereof is, for example, a screwing type,
Any method such as a fitting method or an adhesive method may be used.
Also, a dielectric such as ceramic may be coated or welded by thermal spraying.

With such a configuration, the microwave generated by the microwave generation circuit propagates through the microwave waveguide 4 and is emitted from the microwave emission port 5, and passes through the plasma wave introduction window 3 to generate plasma. It is introduced into the chamber 1.

This microwave spreads radially from the microwave emission port 5, propagates as a surface wave on the surface of the dielectric 33, the medium gas enclosed in the plasma chamber 1 is excited, and plasma 34 is generated. .

In this case, the opening 3 of the plasma chamber 1
Since 2 is formed in a tapered shape, the plasma 34 is
It spreads on the lower surface of the microwave introduction window 3, the sides and the lower surface of the dielectric 33, and further spreads laterally along the tapered shape.

The generation of such plasma 33 produces active species, which are carried by the gas flow toward the exhaust port 9 of the process chamber 7 to process the substrate mounted on the processing stage 8. To do.

As described above, in the second embodiment, the opening portion 32 of the plasma chamber 1 is formed in the tapered portion 32 that expands toward the inside of the plasma chamber 1, and the tapered portion 32 and the tapered portion 32 are continuous with each other. Since the dielectric 33 is attached to the inner wall of the plasma chamber 1, the microwave propagates as a surface wave along the surface of the dielectric 33 having a tapered shape, thereby making the active species density of plasma uniform over a wide area. And the absolute value of the density can be increased. Further, since the dielectric material 30 is not conductive, electrons are not supplied from the surface of the dielectric material 30 and recombination with ions in plasma is less likely to occur, resulting in plasma loss. Can be made extremely small.

Therefore, the range suitable for the processing process can be widened as compared with the conventional area, and the active species density in the entire area can be increased, so that the processing speed can be increased. Further, since only the dielectric 30 is attached, it is possible to easily attach the dielectric 30 to an existing plasma generator to make the active species density of plasma uniform over a wide area and increase the absolute value of the density. (3) Next, a third embodiment of the present invention will be described.
The same parts as those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 4 is a block diagram of a plasma generator corresponding to the third aspect. The microwave waveguide 4 is provided with a kerf called a slot antenna 35 as a microwave emission port.

FIG. 4B is a sectional view as seen from the direction CC 'in FIG. 4, in which a plurality of slot antennas 35 are formed, for example, at four locations. With such a configuration, the microwave generated by the microwave generation circuit propagates through the microwave waveguide 4, is radially emitted from the cut groove of each slot antenna 35, and passes through the plasma wave introduction window 3. It is introduced into the plasma chamber 1.

As described above, since the microwaves are radiated radially from the slot antenna 35, the microwaves are more easily spread on the surface of the dielectric 30. This microwave spreads radially from the slot antenna 35, and becomes a surface wave of the dielectric material 30.
Of the medium, the medium gas enclosed in the plasma chamber 1 is excited, and plasma 36 is generated.

The generation of such plasma 36 produces active species, which are carried by the gas flow toward the exhaust port 9 of the process chamber 7 to process the substrate mounted on the processing stage 8. To do.

As described above, in the third embodiment, since the kerf called the slot antenna 35 as the microwave emission port is formed in the microwave waveguide 4, the microwaves are radiated radially from the slot antenna 35. As a result, it becomes easier to spread on the surface of the dielectric 30. As with the first and second embodiments, the active species density of plasma can be made uniform over a wide area, and the absolute value of the density can be increased. Further, since the dielectric material 30 has no conductivity, electrons are not supplied from the surface thereof, recombination with ions in plasma is less likely to occur, and plasma loss can be made extremely small.

Therefore, the range suitable for the processing process can be widened as compared with the conventional area, and the active species density in the entire area can be increased, so that the processing speed can be increased. Further, since only the dielectric 30 is attached, it is possible to easily attach the dielectric 30 to an existing plasma generator to make the active species density of plasma uniform over a wide area and increase the absolute value of the density. (4) Next, a fourth embodiment of the present invention will be described.

FIG. 5 is a block diagram of the plasma generator.
This plasma generator has a configuration in which a first plasma generator main body 40 and a second plasma generator main body 50 are arranged.

In the first plasma generator main body 40, a plasma wave introduction window 43 is formed in the opening 42 of the plasma chamber 41.
And a microwave waveguide 44 is provided in the plasma wave introduction window 43.

A dielectric 45 is attached to the inner wall of the plasma chamber 41 adjacent to the plasma wave introducing window 43. As the material of the dielectric 45, for example, glass, ceramics or the like is used, and the method of attaching the dielectric 45 may be any of screw fastening type, fitting type and adhesive type. Also, a dielectric such as ceramic may be coated or welded by thermal spraying.

On the other hand, the second plasma generator main body 50
A plasma wave introduction window 53 is provided in the opening 52 of the plasma chamber 51, and a microwave waveguide 54 is provided in the plasma wave introduction window 53.

A dielectric material 55 is attached to the inner wall of the plasma chamber 51 adjacent to the plasma wave introducing window 53. The material of the dielectric 55 is the dielectric 5
Similar to 5, glass, ceramic, etc. are used,
In addition, the method of attachment may be any of screw fastening, fitting, and adhesion. Also, a dielectric such as ceramic may be coated or welded by thermal spraying.

A process chamber 7 is provided below the plasma chambers 41 and 51. The processing target is processed inside the process chamber 7. With such a configuration, each microwave waveguide 44, 45
Of the dielectrics 45, 5 as surface waves.
5 surface.

Therefore, the medium gas enclosed in the plasma chambers 41 and 51 is excited by the microwaves, and the lower surfaces of the microwave introduction windows 43 and 53 and the dielectrics 4 are excited.
Plasmas 46 and 56 are generated which spread to the sides and the lower surfaces of 5, 55.

The generation of such plasmas 46 and 56 produces active species, which are carried by the gas flow toward the exhaust port 9 of the process chamber 7 and cause the substrate mounted on the processing stage 8 to move. Process process.

From the above, the active species density on the upper surface of the processing stage 8 is uniform over a wide area as shown in FIG. 5, and the absolute value of the density is high. Further, since only the dielectric 30 is attached, it is possible to easily attach the dielectric 30 to an existing plasma generator to make the active species density of plasma uniform over a wide area and increase the absolute value of the density.

The present invention is not limited to the above embodiments, but may be modified as follows. For example, in the fourth embodiment, the same effect can be obtained even if only one plasma generator main body is provided and two microwave emission ports are provided by the microwave waveguide.

[0065]

As described in detail above, according to the first aspect of the present invention, it is possible to provide a plasma generator capable of uniformly increasing the active species density of plasma in a wide area. or,
According to the second aspect of the present invention, the plasma can be spread to the lower surface of the microwave introduction window, the side and the lower surface of the dielectric, and can be further spread laterally along the tapered shape, so that the active species density of the plasma is wide. It is possible to provide a plasma generator that can be made uniform and high in area.

According to the third aspect of the present invention, microwaves are radiated radially from the slot antenna and are more easily spread on the dielectric surface, so that plasma active species density can be made uniform and high in a large area. A device can be provided.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing the uniformity of plasma active species density over a wide area and the absolute value of the density.

FIG. 3 is a configuration diagram showing a second embodiment of a plasma generator according to the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of a plasma generator according to the present invention.

FIG. 5 is a configuration diagram showing a fourth embodiment of a plasma generator according to the present invention.

FIG. 6 is a configuration diagram of a conventional plasma generator.

FIG. 7 is a configuration diagram of a conventional plasma generator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plasma chamber, 2 ... Opening part, 3 ... Plasma wave introduction window, 4 ... Microwave waveguide, 5 ... Microwave emission port,
30 ... Dielectric material, 6 ... Gas supply port, 7 ... Process chamber, 8 ... Processing stage, 9 ... Gas exhaust port, 32 ... Tapered portion, 33 ... Dielectric material, 35 ... Slot antenna, 40 ... First plasma generator Main body, 50 ... Second plasma generator main body, 41, 51 ... Plasma chamber, 42, 52
... Openings, 43,53 ... Plasma wave introduction windows, 44,54
... microwave waveguide, 45, 55 ... dielectric.

Claims (3)

[Claims] 1. A plasma generator that introduces microwaves into a reaction vessel through a microwave introduction window to excite a medium gas enclosed in the reaction vessel to generate plasma, at least in the microwave introduction window. A plasma generator characterized in that a dielectric is attached to the inner wall of the reaction vessel in the vicinity thereof. 2. A taper portion that expands toward the inside of the reaction vessel is formed at an opening of the reaction vessel connected to the microwave introduction window, and a dielectric is attached to a portion including the taper portion. The plasma generator according to claim 1, wherein: 3. The plasma generator according to claim 1, wherein a slot antenna is formed in the microwave introduction window.