JP2000299199A - Plasma generating device and plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a plasma state, prevent impedance from lowering without increasing the size of a slot antenna, generate a plasma in a relatively lower frequency, and reduce manufacturing cost and running cost. SOLUTION: This plasma generating device comprises a vacuum container 1 capable of controlling internal pressure, gas supply means 2 for supplying gas in the vacuum container 1, and plasma generating means for generating plasma by radiating an electromagnetic wave in the vacuum container 1 introduced with the gas. The plasma generating means comprises a slot antenna 4 having a slot 41 for radiating an electromagnetic wave formed on a conductor and an ac power source 5 for feeding the slot antenna 4. The slot antenna 4 is formed in a shape having impedance capable of generating plasma in a case of a low feeding frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma generating apparatus and a plasma processing apparatus, and more particularly to an inductively coupled plasma generating apparatus for obtaining high-density plasma, which is used in a process of manufacturing a semiconductor device or a liquid crystal display. Dry etching equipment, ashing equipment, etc. and other fine processing etching, ashing, cleaning,
The present invention relates to a technique suitable for use in a field where high-density plasma can be used, such as surface modification.

[0002]

2. Description of the Related Art In the field of plasma processing apparatuses such as dry etching apparatuses and ashing apparatuses used in the manufacturing process of semiconductor devices and liquid crystal displays, in recent years, plasma generated in a processing chamber has become larger as processing substrates have become larger. Larger diameters are required. On the other hand, it is also required to increase the density of plasma in order to secure a predetermined processing speed such as an etching rate and an ashing rate and a throughput of the apparatus. Among them, with regard to increasing the density of plasma, in order to promote the plasma excitation efficiency, inductively coupled plasma (Inductively Coupled Plasm
a, hereinafter referred to as ICP).

[0003] In the ICP, a high-frequency current is mainly passed through an antenna excitation coil, thereby generating an induction electromagnetic field in a vacuum to generate plasma. And
Its feature is ECR (Electron Cyclotron Resonance)
Equipment, microwave plasma generator, magnetron RI
While the structure of the apparatus is relatively simple as compared with the E apparatus and the like, it is to generate high-density plasma in a vacuum vessel with high uniformity under high vacuum.

When the ICP is used under high pressure, the distribution of the plasma density strongly depends on the externally applied electromagnetic field, that is, the distribution of the electromagnetic field generated by the antenna. Here, in an antenna having a single (Single Design) structure, only the electromagnetic field near the antenna becomes strong,
Localization of the plasma density distribution strongly depends on the shape of the antenna. When the frequency of the high-frequency oscillator is increased in order to increase the plasma excitation efficiency, the antenna having a single structure increases the antenna impedance or localizes the spatial distribution of an electromagnetic field generated by the antenna. On the other hand, shortening the antenna length to suppress an increase in antenna impedance is a contradiction to increasing the plasma diameter. And even if the diameter can be increased, the spatial non-uniformity of the electromagnetic field causes the non-uniformity of the plasma density.

In a single-structure antenna, when the antenna is excited by a high-frequency oscillator, a strong oscillating electric field is generated in a direction perpendicular to the surface of a metal conductor constituting the antenna. On the other hand, a force acts on the plasma, which is a charged particle, by an electric field created by the antenna. Normally, plasma is composed of heavy positive ions and electrons whose mass ratios are different by about 1000 times, so that the sensitivity to an electric field is different. For example, in the case of a frequency band of about 13.56 MHz of industrial frequency,
Heavy ions cannot follow the electric field oscillating at high frequencies, and their position does not change, whereas light electrons can follow enough at this frequency, so only the electrons immediately respond to the electric field and the position changes. A plasma system that changes the temperature is constructed. In such a case, there is no problem if the electric field generated by the antenna is parallel to the antenna coil surface.However, if it is oscillating perpendicular to the antenna coil surface, only electrons are attracted to or separated from the antenna. The electric charge changes between the antenna and the plasma in synchronization with the vibration of the electric field. If this state is viewed in the order of a long time, the result is that electrons are excessively present in the vicinity of the antenna on average, and this excess electron causes the potential of the surface of the dielectric (vacuum vessel) separating the antenna and the plasma to become higher. Induces a relatively low drop effect on plasma and ground potential. Specifically, for example, in the case of a linear antenna, a strong electrostatic field proportional to the inverse cube of the distance r from the antenna is generated, so that a strong Vdc is induced. Here, Vdc is defined as "the time-average potential of the surface of the dielectric separating the antenna and the plasma on the vacuum vessel side".

In addition, since the generation of Vdc causes positive ions to be sputtered on the surface of the vacuum vessel, there is a serious problem in substrate processing that the vacuum vessel surface is hit and impurities are generated. One method of suppressing Vdc is to insert a shielding plate serving as a Faraday shield between the antenna and the plasma. However, the use of the Faraday shield causes attenuation of the radiated electromagnetic field, and energy cannot be supplied to the plasma efficiently, resulting in a plasma processing apparatus with low energy efficiency.

Further, Japanese Patent Application Laid-Open No. 3-79025 discloses a plasma processing apparatus provided with a planar coil for generating an electromagnetic field. This plasma processing apparatus is intended to generate plasma inductively coupled by an electromagnetic field generated by a planar coil, thereby realizing uniform and high density plasma. However, also in this plasma processing apparatus, the above-described Vdc generation mechanism applies exactly, and it is difficult to avoid this problem, such as using a dielectric lens together.

[0008] In order to solve the above-mentioned problem, a technique using a slot antenna has been proposed. A slot antenna is defined as a radiating element composed of an elongated groove or slot formed on a metal conductor surface. This slot antenna has a feature that it does not have an electrostatic field effect that is proportional to the inverse cube of a distance important in a near field, which a linear antenna has. Therefore, the above-described problem of the Vdc generation mechanism can be easily avoided. When plasma is generated using such a slot antenna, a slot opening is provided in a microwave waveguide that can be fed by an oscillator, and electromagnetic waves are radiated using the slot opening as a slot antenna. Techniques for generating plasma are known.

However, when a waveguide is used, the size and shape of the waveguide are limited by the wavelength of the electromagnetic wave to be fed. For example, when an electromagnetic wave having a frequency of 300 MHz is used, the wavelength is 1 m. However, when an electromagnetic wave having a frequency of 3 MHz is used, the wavelength is 100 m. Since the shape becomes huge, it is practically difficult to feed a slot antenna using a waveguide in a region longer in wavelength than a microwave. In the method using a waveguide, the state of the generated plasma is strongly affected by the shape of the electromagnetic wave in the microwave waveguide, such as the shape and arrangement of the slot antenna. There is a problem that these may not be formed into a shape necessary for obtaining a plasma generation area and a plasma generation density required for plasma processing. Furthermore, since an electromagnetic wave having a shorter wavelength than that of the vacuum container in the plasma processing apparatus is used, an interference phenomenon of waves in the vacuum container may be caused, and the generation of plasma may be non-uniform. For this reason, when the aim is to generate large-diameter uniform plasma, the method of using a slot antenna using a waveguide is subject to the above-described restrictions.

[0010] In order to solve the above problem, the present inventors have disclosed a "plasma" having a slot antenna and a high-frequency power supply for feeding power to the slot antenna as described in Japanese Patent Application Laid-Open No. 10-074597. Generator and plasma processing apparatus. " This Japanese Patent Laid-Open No. 10-
No. 0745597 discloses a “plasma generating apparatus and a plasma processing apparatus” that include a processing chamber for accommodating a substrate therein and performing processing on the substrate using plasma, and a processing chamber in which a processing gas is introduced. And plasma generating means for generating plasma by radiating a laser beam.The plasma generating means forms a slot antenna provided in a conductor plate supplied with a high-frequency power supply as a slot antenna, and is provided on both sides of the slot opening. A method of directly providing a power supply point is adopted.Moreover, in this plasma processing apparatus, a plurality of slot openings are formed on the conductor, a power supply point is provided in each of the slots, and a space between the slots is provided. A matching box or the like is provided as phase control means for controlling the power supply phase. In the slot antenna used in this feeding method, the waveguide is not required, and the shape of the slot opening can be prevented from being restricted by the form of the electromagnetic wave generated at that time. Further, since an electromagnetic wave having a relatively low frequency, that is, an electromagnetic wave having a long wavelength can be used, it is possible to prevent wave interference in a vacuum vessel. Therefore,
Since the shape and arrangement of the slot antenna can be designed based on the necessity such as the state of the plasma to be generated, it is preferable as a method for generating a large-diameter uniform plasma.

[0011]

In the plasma generating apparatus to which the above-mentioned slot antenna is applied, in order to reduce the energy required for plasma generation, 100 MHz
There is a demand to use a relatively low frequency, such as: However, when plasma is generated by using a relatively low frequency in the slot antenna, the slot antenna is likely to be short-circuited due to insufficient impedance, and the slot antenna is large in size due to weak magnetic coupling with the plasma. Was required. Further, as described in JP-A-10-074597, the length of the folded slot antenna is about 200 mm when the power supply frequency is 300 MHz, and an annular slot antenna when the power supply frequency is 500 MHz. Can be set as small as about 300 mm, but when the power supply frequency is about 100 MHz or less, the length of the required slot opening becomes large and the entire device becomes large, so there has been a demand to improve this. . Since the cost of an oscillator of about 100 MHz or more and a matching box for synchronizing the phase thereof are high, in order to reduce the manufacturing cost of the device, a standard industrial frequency of 13.56 MHz or 27.12 is used.
There is a demand to use an oscillator of 40 MHz and 40.68 MHz and a corresponding matching box. In this case, since the wavelength of the generated electromagnetic field is large, if the slot antenna has a necessary length, the device is as large as about 13 m. There was a problem that it could not be put to practical use.

Further, in the technique described in Japanese Patent Application Laid-Open No. 10-074597, a plurality of slot openings are formed on the conductor in order to improve the generation area and generation density of the generated plasma. In this case, there is a problem that it may be difficult to control the synchronization of the power supply frequency for a large number of slots. By forming the part on the conductor, there is a problem that the impedance as an antenna is reduced and short-circuit is likely to occur, and the cost of the phase corrector is high, thereby reducing the manufacturing cost of the device. Therefore, there was a request to take some measure.

Further, as shown in FIG. 34, the arrangement relationship between the slot antenna and the vacuum container is, as shown in FIG. 34, outside the vacuum container C2 in which the slot antenna C1 is disposed below.
That is, while being placed in the atmosphere, the vacuum vessel C2 has an opening C21 near the lower side of the slot C11, and a dielectric C such as quartz closing the opening C21.
3 were arranged. Here, the dielectric C3 guides the AC electromagnetic field generated from the slot antenna C1 from the opening C21 to the inside of the vacuum container C2, and also connects the vacuum container C2 to the O.
It is provided to seal with the ring C22 and the like to maintain the vacuum inside the vacuum vessel C2.

However, in such an arrangement, the opening C2
In order to increase the area of the slot antenna C1 secured inside the vacuum vessel C2 through
When the area of 1 is increased, it is necessary to increase the thickness of the dielectric C3 in order to maintain the structural strength against the atmospheric pressure outside the vacuum vessel C2 and maintain the vacuum. Such an increase in the thickness of the dielectric C3 lowers the osmotic potential fed to the antenna feeder and also lowers the line density of magnetic force intersecting with the plasma P. As a result, the lighting start power of the plasma P increases and the magnetic coupling with the plasma P decreases. That is, the thickness of the dielectric C3 cannot be reduced, the thickness of the dielectric C3 is limited, and the distance between the slot antenna C1 and the inside of the vacuum vessel C2 cannot be arbitrarily adjusted. There is a problem that it is difficult to control the penetration of the voltage supplied to the power supply. Further, since the metal conductor surface of the slot antenna C1 secured in the vacuum vessel C2 through the opening C21 of the vacuum vessel C2 is restricted by the size of the dielectric C3, the electromagnetic field emission of the slot antenna C1 is restricted. This limits the opening area of the surface, which impairs energy efficiency and prevents the plasma P from increasing in diameter. In the slot antenna, a point to be connected to the ground is required as a feeding point, but other points need to be insulated, and there may be a case where it is difficult to achieve compatibility with sealing conditions in a vacuum vessel.

The present invention has been made in view of the above circumstances, and aims to achieve the following objects. Improvement of the plasma state, such as enlargement of the plasma generation area, uniformization and improvement of the plasma generation concentration, prevention of an increase in plasma lighting start power, and improvement of magnetic coupling with the plasma. To prevent a drop in impedance without increasing the size of the slot antenna, and to enable plasma to be generated at a relatively low frequency. Reduce manufacturing and running costs.

[0016]

According to the present invention, there is provided a plasma generating apparatus comprising: a vacuum vessel having a controllable internal pressure; gas supply means for supplying a gas into the vacuum vessel; and a vacuum vessel into which a gas is introduced. Plasma generating means for generating plasma by radiating electromagnetic waves into the plasma generating apparatus, wherein the plasma generating means supplies a slot antenna having a slot for radiating electromagnetic waves to a conductor, and feeds the slot antenna. The above problem has been solved by providing an AC power supply for performing the above-mentioned operation, wherein the slot antenna has an impedance capable of generating plasma even at a low power supply frequency. Here, in the present invention,
The low power supply frequency is a frequency at which an electromagnetic wave having a wavelength larger than the size in the vacuum vessel is generated, that is, the vertical, horizontal, height, diagonal, radius, and 1 of a portion of the vacuum vessel into which a gas is introduced.
This means a frequency smaller than the frequency of an electromagnetic wave having a wavelength equal to one dimension selected from dimensions such as side lengths. In the plasma generator of the present invention, the slot antenna as a magnetic current source antenna uses the duality of an electromagnetic field between the conductor shape and the slot shape, and a linear antenna based on the Babinet principle. Thus, it is possible to set a two-dimensional structure or a three-dimensional structure. In the plasma generator of the present invention, the shape of the conductor and the shape of the slot in the slot antenna as a magnetic current source antenna may be a linear antenna based on Babinet's principle, such as a cylindrical surface structure, a spherical structure, and a refraction surface. It is preferable to set the shape to increase the density of the plasma generated inside by utilizing the duality of the electromagnetic field between them. In the plasma generator of the present invention, the conductor of the slot antenna can be configured as a part or all of the vacuum vessel. In the plasma generator according to the present invention, two feeding points to the slot antenna are provided.
It is possible to set three or four places, or to set the feed point to one place and set the conductor to the ground potential, and to set the feed point to a position where the radiation state in the slot antenna is optimized. It is. In the plasma generator of the present invention, it is possible to provide the slot at one location, or at two or more locations connected in parallel or in series. The plasma processing apparatus of the present invention, a processing chamber for accommodating a substrate therein and processing the substrate using plasma, a gas supply unit for supplying a processing gas into the processing chamber,
In a plasma processing apparatus having plasma generation means for generating plasma by radiating electromagnetic waves into the processing chamber into which the processing gas has been introduced, and an exhaust means for exhausting the processing chamber to a desired pressure, the plasma generation means includes: It has a slot antenna in which a slot for radiating electromagnetic waves is formed in a conductor, and an AC power supply for feeding power to the slot antenna, and the slot antenna is shaped to have an impedance capable of generating plasma even at a low feeding frequency. This has solved the above-mentioned problem. Here, the plasma generating means has substantially the same configuration as that described in the plasma generating apparatus.

A slot antenna is defined as a radiating element composed of a groove or a slot formed on a metal conductor surface. The slot antenna is also called a magnetic current antenna, and the magnetic current is regarded as a source of electromagnetic wave motion. Unlike a linear antenna, a magnetic field parallel to the opening surface at the slot opening cancels out on the front and back surfaces to zero. It has the following physical characteristics. Also, based on the Babinet principle based on the duality of the electromagnetic field, the slot antenna has the duality of the electromagnetic field (the property that the electric field and the magnetic field alternate).
Although there is a corresponding linear antenna having the following characteristics, the characteristics can be easily analyzed. However, the slot antenna has a static electric field effect that is proportional to the inverse cube of the distance that is important in the near field. The feature is that it does not have. When a slot antenna is used to generate plasma, an elongated slit is usually formed on a metal conductor plate. By adopting a deformed form or a twisted form while maintaining the characteristics of the magnetic current source antenna while maintaining the characteristics of the magnetic current source antenna, the impedance of the slot antenna and the magnetic coupling with plasma are improved. On this occasion,
By making the slot antenna have an impedance capable of generating plasma without increasing the size of the slot antenna even at a low power supply frequency, it is possible to prevent wave interference in the vacuum vessel. In addition, taking advantage of the fact that the slot antenna is a planar antenna, the slot antenna can be part or all of the vacuum vessel, and at the same time, the antenna conductor has a cylindrical planar structure, hemispherical structure, refraction surface, etc. By increasing the density of the plasma generated in the slot antenna and appropriately selecting the shape of the slot, it is possible to set the feed point for the slot antenna to one point and to set the conductor to the ground potential. This also eliminates the need to provide a dielectric between the slot antenna and the vacuum vessel for the purpose of maintaining and sealing the vacuum. The distance between the plasma and the antenna, the surface area of the antenna can be freely set, and magnetic or static Controllability of electrical coupling is improved. As a result, the electromagnetic radiation surface is increased, the coupling between the antenna and the plasma is increased, and the power supply efficiency can be improved and the diameter of the plasma can be increased. Further, it is possible to effectively supply power to the slot antenna by setting the feeding points to the slot antenna at two, three, and four locations corresponding to the shape of the slot. In addition, by setting the slot antenna as a part or the whole of the vacuum vessel and supplying power to the floating island type slot from one power supply point, it is not necessary to set the conductor to the ground potential, that is, to insulate the conductor. Further, by setting the frequency for feeding the slot antenna to be variable and changing the setting position of the feeding point with respect to the slot in accordance with the frequency, the feeding point optimizes the radiation state in the slot antenna. It is possible to plan. In addition, the slot is located at one place or
It is possible to improve the power supply efficiency and increase the diameter of the plasma by providing two or more portions connected in parallel or in series.

[0018]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a plasma generator and a plasma processing apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a plasma processing apparatus according to the present embodiment, and specifically, is an example of an ICP ashing apparatus used for removing a resist in a semiconductor device manufacturing process. In the figure, reference numeral 1 denotes a vacuum chamber (processing chamber), 2 denotes an O ₂ gas supply source (gas supply means), 3 denotes a vacuum pump (exhaust means), 4 denotes a slot antenna (plasma generation means), and 5 denotes an RF oscillator ( W is a semiconductor wafer (substrate),
It is.

As shown in FIG. 1, the present plasma processing apparatus includes a vacuum chamber 1 (a vacuum vessel whose internal pressure can be controlled), an O ₂ gas supply source 2 (gas supply means), and a slot antenna 4 (plasma generation means). ), And a plasma generator comprising an RF oscillator 5 (high-frequency power supply, plasma generating means).

An exhaust port 8 is provided at the lower part of the metal vacuum chamber 1, and the vacuum pump 3 is connected to the exhaust port 8 via an exhaust pipe 10 having a valve 9. And
The inside of the vacuum chamber 1 is evacuated to about several Pa to several hundred Pa through the exhaust port 8 by the operation of the vacuum pump 3. Further, a process stage 11 for holding a semiconductor wafer W to be processed is provided below the vacuum chamber 1, for adjusting the position (height) of the process stage 11 in the vacuum chamber 1. Stage elevator 12 is installed. Here, in the vacuum chamber 1, an internal shape into which gas is introduced can be selected from those having a rectangular parallelepiped shape, a cylindrical shape, a hemispherical shape, a structure having a refraction surface, and the like. The dimensions, such as the length, width, height, diagonal, radius, and length of one side, of the portion into which the gas is introduced are set to values ranging from several cm to several tens of meters.

A gas inlet 1 is provided above the vacuum chamber 1.
3 and a gas introduction pipe 1 provided with valves 14 and 15
6 consists of O ₂ gas cylinder or the like via the O ₂ gas supply source 2
Is connected. Then, O ₂ gas are configured to be introduced is a process gas for the resist removal in the vacuum chamber 1 from the O ₂ gas supply source 2. Further, a purge gas introduction pipe 17 is connected in the middle of the gas introduction pipe 16, through which, for example, N ₂ gas or the like for purging the inside of the vacuum chamber 1 is introduced.

In the upper part of the vacuum chamber 1, an electromagnetic wave is emitted into the vacuum chamber 1 to excite the plasma P,
A slot antenna 4 for generating the light is provided, and an opening 1a for transmitting an electromagnetic wave radiated from the slot antenna 4 is provided. Slot antenna 4
Is, for example, a flat conductor made of aluminum or the like, and as shown in FIGS.
And constitutes a part of the vacuum vessel 1 whose internal pressure can be controlled. Sealing means such as an O-ring 1b is provided between the slot antenna 4 and the vacuum chamber 1 around the opening 1a, and the opening 1a is adjusted with the osmotic potential and the surface of the slot antenna 4 is hit by plasma. A dielectric 18 made of quartz, ceramics, or the like is provided to prevent impurity diffusion due to antenna contamination in which impurities are generated. On the upper side of the slot antenna 4, an aluminum shield 4a is provided on the slot antenna 4 so as to cover the slot antenna 4. A slot 41 is provided at the center of the slot antenna 4 in a plan view, and feed points 43 and 44 to the slot antenna 4 are provided near the slot 41.

As will be described later, the slot 41 has a shape capable of generating plasma even in the case of a low power supply frequency.
As shown in the figure, a seal dielectric (dielectric) 25 continuously arranged from the position covering the slot 41 to the inside of the slot 41 in a plan view at a position outside the vacuum chamber 1.
Is provided. The dielectric seal dielectric 25 made of quartz, ceramics or the like maintains and seals the vacuum of the vacuum chamber 1 together with sealing means such as an O-ring 4b provided on the surface of the slot antenna 4 outside the slot 41 in plan view. It is a sealing means. Further, as shown in FIG. 2, feeding points 43 and 44 can be provided inside the slot 41. For example, power can be fed to the slot antenna 4 from inside the slot 41. Thereby, when viewed from the side of the slot antenna 4 where the plasma P is generated, the high-frequency current is distributed on the surface side, and the effect of efficiently transmitting the power supplied to the slot antenna 4 to the plasma P can be obtained. As shown in FIG. 1, the slot antenna 4 is insulated from the metal vacuum chamber 1 by an insulating portion 1c of the vacuum chamber 1 to which the O-ring 1b is attached.
Attached to. The matching box 26 and the RF oscillator 5
Are sequentially connected, and the feeding point 44 is grounded to be at the ground potential.

As shown in FIG. 1, a box-shaped conductor aluminum shield 4a is arranged above the slot antenna 4, and this aluminum shield 4a is connected to the slot antenna 4 via a dielectric 4c made of quartz, ceramics or the like. It is provided in an insulated state. With this configuration, the electromagnetic field radiated from the slot 41 is transmitted to only the lower part without reaching the upper part, so that the electromagnetic wave can be efficiently sent into the vacuum chamber 1 and the slot antenna 4
Can be insulated. Further, the aluminum shield 4 and the vacuum chamber 1 are connected to each other so that the electromagnetic waves inside the aluminum shield 4 do not escape to the outside. The insulator 4c may not be provided as long as the aluminum shield 4a and the slot antenna 4 are in an insulated state. And the feeding point 4 inside the slot 41
3, the power is supplied by a coaxial tube following the matching box 26 and the RF oscillator 5 while penetrating the aluminum shield 4a in an insulated state. Further, a matching box 27 for stage bias and an RF oscillator 28 are also sequentially connected to the processing stage 11. The RF oscillators 5 and 28 have a frequency of several kHz to 100M.
It is possible to oscillate a low power supply frequency of about Hz. Preferably, the industrial frequency is 13.56 MHz, or 27.12 MHz or 40.68 M which is an integral multiple thereof.
It is possible to oscillate a frequency selected from Hz.

The above-structured plasma processing apparatus is
When used for photoresist ashing process
A few MT in the vacuum chamber 1 using the vacuum pump 3
After exhausting to about Torr to several Torr, O_TwoIntroduce gas
And the RF oscillator 5
Apply frequency. Then, the slot of slot antenna 4
Electromagnetic wave is radiated from the vacuum chamber 1
Razuma P occurs and O _TwoGas is dissociated in plasma P
Oxygen radicals formed and resist on semiconductor wafer W formed
Chemical reaction causes the resist to decompose and vaporize
Removed.

In the plasma processing apparatus of the present embodiment, as described later, a slot 41 is formed on one conductor plate (slot antenna) 4 so as to have an impedance capable of generating plasma even at a low power supply frequency. In addition, the electromagnetic radiation surface is increased as in the case where a plurality of slot antennas are arranged in parallel. Therefore, since the intensity distribution of the electromagnetic field in the vacuum chamber 1 can be made uniform, the uniformity of the plasma density can be easily controlled, and the plasma density can be maintained while maintaining the uniformity of the plasma density. The diameter can be increased. As a result, according to the plasma processing apparatus of the present embodiment, a large-diameter semiconductor wafer can be processed with good uniformity, and a favorable plasma processing apparatus for increasing the diameter can be obtained. Also,
Since the slot antenna 4 is a planar antenna, the slot antenna 4 is made a part of the vacuum chamber 1 and at the same time,
By making the antenna conductor a cylindrical surface structure, a hemispherical structure, a refraction surface, or the like, the density of the plasma P generated inside is increased, and by appropriately selecting the shape of the slot 41, power is supplied to the slot antenna 4. With the point 43 as one location, the conductor can be at ground potential. This eliminates the need to provide a dielectric between the slot antenna 4 and the vacuum chamber 1 for the purpose of maintaining and sealing the vacuum.
, And the surface area of the slot antenna 4 can be freely set, and the controllability of magnetic or electrostatic coupling between the plasma P and the slot antenna 4 is improved. As a result, the electromagnetic radiation surface is increased, the coupling between the slot antenna 4 and the plasma P is increased, and the power supply efficiency can be improved and the diameter of the plasma P can be increased.

FIGS. 3 to 33 show pairs of a slot antenna (a) and a dual linear antenna (b). The slot 41 is shown in FIG.
A basic rectangular slot 41 provided in the conductor of the planar slot antenna 4 shown in FIG.
By utilizing the duality of the electromagnetic field between the linear antenna and the linear antenna based on the Babinet principle, the linear antenna 41 ′ shown in FIG.
Based on the analysis shown in FIG. 4, while having topological congruency and maintaining the characteristics of the magnetic current source antenna, a two-dimensional structure or a three-dimensional structure as shown in FIGS. It has a deformed structure, and has a shape capable of generating plasma even at a low power supply frequency. Here, the feeding points 23 and 24 to the slot antenna 4 are set at two or four places depending on the shape of the slot 41 set respectively, or the feeding point 23 is set to one place and the conductor is set to the ground potential. Is set. This allows
The impedance of the slot antenna 4 and the magnetic coupling with plasma are improved.

Hereinafter, each configuration example will be described. In the configuration example shown in FIG. 4, the slot 41 has a horizontally long, substantially U-shape, and a feeding point 43 is provided inside near the bottom and a feeding point 44 outside. As an example of this configuration, FIG.
The length dimension can be set to approximately half or less of the basic shape shown in FIG. In the configuration example shown in FIG. 5, the slot 41 is substantially H-shaped, and feed points 43 and 44 are provided at the center position. Also in this configuration example, as in the case of FIG. 4, the length dimension can be set to approximately half or less of the basic shape shown in FIG. In the configuration example shown in FIG. 6, the slot 41 spirals in a substantially lightning pattern in a rectangular shape, and feed points 23 and 24 are provided at the center position. In this configuration example, by setting the number of bent portions in one slit 41, the required length of the slit 41 is obtained, the electromagnetic radiation surface is increased, and the density of the slit 41 in the plane is improved. Therefore, the density of the generated plasma P can be increased, and the plasma P generated almost uniformly in a rectangular shape in plan view can be obtained. Therefore, when the planar shape of the vacuum chamber 1 is rectangular,
The density of the plasma P inside the vacuum chamber 1 can be made uniform. In the configuration example shown in FIG. 7, a slot 41 connects three-quarter arcs in opposite directions to form a substantially S-shape, and feed points 23 and 24 are provided at the center position. In this configuration example, since there is no bent portion, the intensity density uniformity of the radiated radio wave is improved, and the length dimension can be set to approximately half or less of the basic shape shown in FIG. . In the configuration example shown in FIGS. 8 and 9, the slot 41 has a shape that is twisted around the feeding points 43 and 44 from the configuration example shown in FIG. 7. Here, in the configuration example of FIG. 8, a semi-arc and a quadrant having a radius equal to the diameter of the semi-arc are connected to each other.
In the configuration example of FIG. 8, a quadrant of the same shape is connected to the configuration example of FIG. 8, and a semi-arc whose radius is the diameter of the quadrant is connected. In these configuration examples, in addition to exhibiting the same performance as the configuration example shown in FIG. 7, the density in the plane of the slit 41 can be further improved, and the intensity density uniformity of the radiated radio wave can be improved, and the intensity density uniformity can be improved. Can be achieved. In the configuration examples shown in FIGS. 4 to 9 described above, it is possible to contribute to the improvement of the impedance and the magnetic coupling with the plasma. If the representative length of the slot antenna 4 is on the order of several tens of cm, the number of RFs is 1
It can be used for plasma generation applications at relatively low RF frequencies on the order of 0 MHz.

In the configuration example shown in FIG. 10, the slot 41 has a cross shape, and four feeding points 43, 43, 44, and 44 are provided at the center thereof. here,
The feeding points 43 are connected to the matching box 26 and the RF oscillator 5. This configuration example has a structure in which two linear slots 41 shown in FIG. 3 are parallelized, the output is increased, and each feeding point 43, 43, Since the positions 44 and 44 are close to each other, there is no need to provide a phase corrector or the like. In the configuration examples shown in FIGS. 11 to 13, the slot 41 has a cross shape, as in the configuration example shown in FIG. 10, and the lightning pattern is substantially similar to the configuration examples shown in FIGS. 6 to 9. It is shaped to be twisted around the feeding points 43 and 44 in a spiral or spiral shape. In this configuration example, FIG.
3 has a structure in which two linear slots 41 shown in FIG. 3 are arranged in parallel, and the output is increased. As in the case of the configuration examples shown in FIGS. , The intensity density uniformity of the radiated radio wave can be improved, and the intensity density uniformity can be improved.

In the configuration examples shown in FIGS. 14 and 15,
7 and 12, they are formed by circular arcs, but the end portions are extended and the feeding points 43,
An arc having a radius equal to the diameter of the semicircular arc near 44 is connected. In this configuration example, since there is no bent portion, the intensity density uniformity of the radiated radio wave is improved, and the outer shape is circular. Therefore, when the planar shape of the vacuum chamber 1 is circular, the vacuum chamber The density of the plasma P inside 1 can be made uniform up to its peripheral portion. FIG. 16 shows a conventional folded slot antenna, and FIGS. 14, 15, 17 to
This is the base shape for setting the shape of the configuration example 9. This has a rectangular loop shape in which the ends of the groove are connected to each other, and there are a conductor outside the slot and a conductor inside the slot. The configuration example shown in FIG. 14 has a structure in which one outer conductor and two middle conductors are arranged via slots 41 like a pattern of a thick pole. Since the conductor is divided into three parts, two-pole power supply or two-pole power supply at two power supply points is possible. 17 and 18 are floating island types in which a conductor outside the slot 41 and a conductor inside the slot 41 are present, as in the configuration example of FIG. 16, FIG. 17 is a circle, and FIG. With an outer shape of In this configuration example, similar to the configuration examples of FIGS.
1 can be improved, the intensity density uniformity of the radiated radio wave can be improved, the intensity density uniformity can be improved, and the feeding point 43 is connected to the matching box 26 and the RF oscillator 5. However, the feeding point 44 may not be provided. In this case, the slot antenna 4
May be set to the ground potential on the outermost side. Therefore, the slot antenna 4 constituting a part of the vacuum chamber 1 does not need to consider the insulating property, so that the configuration can be further simplified and the manufacturing cost can be reduced. 17 and FIG.
Is an example in which the slots 41 are nested and arranged like a maze. In this structure, a large impedance can be obtained with a small area. FIG.
Also has the same features as the above-described floating island type configuration example shown in FIG. The configuration examples shown in FIGS. 14 to 19 can use the slot antenna 4 in a self-resonant state, and if the representative length of the slot antenna 4 is on the order of several tens of cm, the RF number 10
It is suitable for use of a slot antenna at a relatively high frequency on the order of 0 MHz.

In the configuration examples shown in FIGS. 20 to 25, the conductor constituting the slot antenna 4 has a three-dimensional cylindrical shape. The configuration example shown in FIG. 20 is a modified example of the configuration example shown in FIG. 3, the configuration example shown in FIG. 21 is a modified example of the configuration example shown in FIG. 16, and the configuration example shown in FIG. 23 is a modification example of the configuration example shown in FIG. 9, the configuration example shown in FIG. 24 is a modification example of the configuration example shown in FIG. The configuration example shown in FIG. 25 is a modified example of the configuration example shown in FIG. The configuration examples shown in FIGS. 20 to 25 have the same features as the configuration example which is the basis of the deformation shown in FIGS. 3 to 19, and generate plasma inside the cylinder, thereby obtaining the structure shown in FIGS. The plasma generation density can be more spatially improved than the planar shape (two-dimensional structure) shown in FIG.

In the configuration examples shown in FIGS. 26 to 29, the conductor forming the slot antenna 4 has a three-dimensional spherical shape. The configuration example shown in FIG. 26 is a modified example of the configuration example shown in FIG. 9, the configuration example shown in FIG. 27 is a modified example of the configuration example shown in FIG. 10, and the configuration example shown in FIG. 29 is a modification of the configuration shown in FIG. 29, and the configuration shown in FIG. 29 is a modification of the configuration shown in FIG. The configuration examples shown in FIGS. 26 to 29 have the same features as those of the configuration example based on the modifications shown in FIGS. 3 to 19, and generate plasma inside the cylinder, thereby obtaining the configuration examples shown in FIGS. 20 can improve the plasma generation density more spatially than the planar shape (two-dimensional structure) shown in FIG. 1, and can further improve the plasma generation density more spatially than the configuration examples shown in FIGS. Can be. In particular, in the configuration examples shown in FIG. 28 and FIG.
And the structural properties of the vacuum chamber 1 as a structural material can be made extremely excellent.

In the configuration examples shown in FIGS. 30 to 33, the conductor forming the slot antenna 4 is formed by combining two-dimensionally structured planes into a three-dimensional refraction plane shape. The configuration example shown in FIG. 30 is a modified example of the configuration shown in FIG. 3, in which a slot 41 is arranged so as to straddle the polygonal line L on four conductors of the slot antenna refracted by the polygonal line L and made two planes. Feed points 43 and 44 are arranged on L. This configuration example has the same features as the configuration on which the modification shown in FIG. 3 is based, and
As compared with the planar shape (two-dimensional structure) shown in FIG. 3, the plasma generation density can be spatially improved. FIG.
5 is a modified example of the configuration example shown in FIG. 5, in which a slot antenna 4 is bent over a broken line L and made into two planes so that a slot 4 extends over the broken line L.
1 and the feeding points 43 and 44 on the polygonal line L. This configuration example has the same features as the configuration example which is the basis of the deformation shown in FIG. 5, and also has a more spatially reduced plasma generation density than the configuration example of the planar shape (two-dimensional structure) shown in FIG. Can be improved. FIG.
The configuration example shown in FIG. 2 is a modification of the configuration example shown in FIG.
The slit 41 has a rectangular outer shape, and is arranged so as to straddle the broken line L on the four conductors of the slot antenna refracted from the broken line L and made two planes, and feed points 43 and 44 are arranged on the broken line L. is there. This configuration example has the same features as the configuration that is the basis of the deformation shown in FIG. 14 and also has the same features as those having a square outer shape, and is thus smaller than the planar shape (two-dimensional structure) shown in FIG. In addition, the plasma generation density can be spatially improved.
In the configuration examples shown in FIGS. 30 to 32, for example, in the vacuum chamber 1 having a rectangular parallelepiped shape, the vacuum chamber 1 is used by being arranged on the peripheral portion in combination with a slot antenna 4 having another configuration provided in the center thereof. In this case, it is possible to further increase the diameter of the generated plasma and make the plasma density uniform. The configuration example shown in FIG. 33 is a modification of the configuration example shown in FIG. 10. In the slot antenna 4 conductor refracted by the broken line L2 and formed into a so-called four pyramid-shaped four planes, the center of the slit 41 is positioned at the vertex. It is arranged so that.
This configuration example has the same features as the configuration that is the basis of the deformation shown in FIG. 10, and can further improve the plasma generation density more spatially than the planar shape (two-dimensional structure) shown in FIG. 10. it can.

The configuration examples shown in FIGS. 4 to 33 are examples of the form change of the slot antenna according to the present invention, and the shape of the conductor and the shape of the slot in the slot antenna as the magnetic current source antenna are Babinet. Utilizing the duality of the electromagnetic field between the antenna and the linear antenna based on the principle of the above, it is set to a shape structure that increases the density of the plasma generated inside, and the impedance that can generate the plasma even at low power supply frequency Other structures are possible as long as the slot antenna has the shape, and the deformation of the slot antenna can be applied to various other forms.

According to this embodiment, even at a relatively low frequency, it is possible to prevent the impedance from lowering without increasing the size of the slot antenna, and to improve the magnetic coupling with the plasma. Can be given. This makes it possible to use a transmitter that generates an electromagnetic wave having a relatively long wavelength, and also suppresses non-uniformity of plasma generation due to interference of the electromagnetic wave in the vacuum vessel. In addition, since there is no need to provide a dielectric between the plasma and the slot antenna in order to seal the vacuum vessel, the distance between the plasma and the slot antenna can be set arbitrarily, and the osmotic potential related to the lighting of the plasma can be reduced. The controllability is suppressed, the magnetic coupling between the plasma and the antenna is improved, the coupling area is increased, the power supply efficiency is improved, and the diameter of the plasma can be increased.

In this embodiment, the power supply frequency to the slot antenna 4 is set to about 100 MHz or less. However, the present invention is not limited to this range, and the generated electromagnetic wave may be a high frequency in the UHF band. In the floating island type slot antenna 4 described above, the feeding point 43
The non-connected portion is set to the ground potential, and the structure without the dielectrics 1c and 4c for insulating the slot antenna 4 can be adopted. Further, the oscillation frequency of the RF oscillator 5 is made variable so that the frequency for feeding power to the slot antenna 4 is set to be changeable. In this case, the position where the feeding points 43 and 44 in the slot antenna 4 are provided with the change of the feeding frequency. By setting to move, the state such as the intensity of the electromagnetic wave radiated from the slot antenna 4 is optimized, the diameter of the generated plasma is increased, and the plasma generation state such as the density is improved. It becomes possible. In addition to the above-described configuration, the configuration can be modified within the scope of the present invention. A configuration in which the vacuum vessel is hermetically sealed by the dielectric 18, and two or more slots 41 are formed in the slot antenna , These are connected in series or in parallel, aluminum shield 4
A configuration in which a is formed integrally with the slot antenna 4 is applicable.

[0037]

According to the plasma generating apparatus and the plasma processing apparatus of the present invention, the following effects can be obtained. (1) Since the slot antenna has an impedance capable of generating plasma without increasing the size of the slot antenna even at a low power supply frequency, the plasma generation area is increased and the plasma generation concentration is uniform. Improvement of plasma state, such as improvement and improvement, prevention of increase of plasma lighting start power, improvement of magnetic coupling with plasma, etc., and suppression of non-uniformity of plasma generation due to interference of electromagnetic waves in a vacuum vessel be able to. (2) When the shape of the conductor and the shape of the slot in the slot antenna as a magnetic current source antenna are electromagnetic, such as a cylindrical surface structure, a spherical structure, a refraction surface, etc., between a linear antenna based on Babinet's principle. Using the duality of the world,
By setting the shape to increase the density of plasma generated inside, it is possible to prevent a decrease in impedance without increasing the size of the slot antenna and to generate plasma at a relatively low frequency. . (3) Since the conductor of the slot antenna is configured as a part or the whole of the vacuum vessel, and a plasma can be generated by a low power supply frequency, a high-frequency oscillator, a matching box, and the like that are costly , The production cost and the running cost can be reduced. (4) Because the conductor of the slot antenna is configured as a part or the whole of the vacuum container, it is not necessary to provide a dielectric between the plasma and the slot antenna to seal the vacuum container. , The distance between the plasma and the slot antenna can be set arbitrarily, suppressing the controllability of the osmotic potential related to the lighting of the plasma, improving the magnetic coupling between the plasma and the antenna, increasing the coupling area,
The power supply efficiency can be improved, and the diameter of the plasma can be increased.

[Brief description of the drawings]

FIG. 1 is a front view showing an embodiment of a plasma generator and a plasma processing apparatus according to the present invention.

FIG. 2 is a front view showing the vicinity of a slot in FIG. 1;

FIG. 3 is a plan view showing a slot antenna.

FIG. 4 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 5 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 6 is a plan view showing a structural example of a slot antenna of the plasma generating apparatus and the plasma processing apparatus according to the present invention.

FIG. 7 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 8 is a plan view showing a configuration example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 9 is a plan view illustrating a structural example of a slot antenna of the plasma generating apparatus and the plasma processing apparatus according to the present invention.

FIG. 10 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 11 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 12 is a plan view showing a configuration example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 13 is a plan view showing a structural example of a slot antenna of the plasma generating apparatus and the plasma processing apparatus according to the present invention.

FIG. 14 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 15 is a plan view illustrating a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 16 is a plan view showing an example of a folded slot antenna.

FIG. 17 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 18 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 19 is a plan view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 20 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 21 is a perspective view showing an example of the structure of a slot antenna of a plasma generator and a plasma processing apparatus according to the present invention.

FIG. 22 is a perspective view showing a configuration example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 23 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 24 is a perspective view showing an example of a structure of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 25 is a perspective view showing a structural example of a slot antenna of a plasma generator and a plasma processing apparatus according to the present invention.

FIG. 26 is a perspective view showing a structural example of a slot antenna of a plasma generating apparatus and a plasma processing apparatus according to the present invention.

FIG. 27 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 28 is a perspective view showing a structural example of a slot antenna of a plasma generator and a plasma processing apparatus according to the present invention.

FIG. 29 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 30 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 31 is a perspective view showing a structural example of a slot antenna of a plasma generator and a plasma processing apparatus according to the present invention.

FIG. 32 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 33 is a perspective view showing a structural example of a slot antenna of the plasma generator and the plasma processing apparatus according to the present invention.

FIG. 34 is a front view showing a conventional plasma generator.

[Explanation of symbols]

1 ... vacuum chamber (processing chamber, the vacuum chamber) 1a ... opening 2 ... O ₂ gas supply source (gas supply means) 3 ... vacuum pump (evacuation means) 4 ... slot antenna (plasma generation means) 5 ... RF oscillator (RF Power supply, plasma generating means) 18, 25 Dielectric 41 Slot 43, 44 Feed point P Plasma W Semiconductor wafer (substrate)

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kenichi Kojima 992 Taniyasu, Kunitachi, Tokyo F-term in Plasma System Co., Ltd. (reference) 4K057 DA16 DD01 DM31 DM37 DM38 DM40 DN01 5F004 AA01 BA20 BB13 BC08 BD01 DA26 DB26

Claims (7)

[Claims] 1. A vacuum vessel whose internal pressure can be controlled, gas supply means for supplying a gas into the vacuum vessel, and plasma is generated by radiating electromagnetic waves into the vacuum vessel into which the gas has been introduced. And a plasma generating device, comprising: a slot antenna in which a slot for radiating electromagnetic waves is formed in a conductor; and an AC power supply for feeding power to the slot antenna. A plasma generator having an impedance capable of generating plasma even at a low power supply frequency. 2. The slot antenna as a magnetic current source antenna, wherein the shape of the conductor and the shape of the slot are determined by utilizing the duality of an electromagnetic field between the antenna and a linear antenna based on the Babinet principle. 2. The plasma generator according to claim 1, wherein the plasma generator is set to have a three-dimensional structure or a three-dimensional structure. 3. The shape of the conductor and the shape of the slot in the slot antenna as a magnetic current source antenna are internally formed by utilizing duality of an electromagnetic field between the antenna and a linear antenna based on the Babinet principle. 3. The plasma generating apparatus according to claim 1, wherein the plasma generating apparatus is configured to increase the density of generated plasma. 4. The plasma generator according to claim 1, wherein the conductor of the slot antenna is configured as a part or the whole of the vacuum vessel. 5. The power supply point to the slot antenna is 2
Or three or four places, or one feed point and the conductor is set to the ground potential, and the feed point is set to an optimized position of the radiation state in the slot antenna. The plasma generator according to any one of claims 1 to 4, wherein the plasma generation is performed. 6. The plasma generator according to claim 1, wherein the slot is provided at one location or at two or more locations connected in parallel or in series. 7. A processing chamber for accommodating a substrate therein and processing the substrate using plasma, a gas supply means for supplying a processing gas into the processing chamber, and the processing chamber into which the processing gas is introduced. In a plasma processing apparatus having plasma generating means for generating plasma by radiating electromagnetic waves to the plasma processing means and exhaust means for exhausting the processing chamber to a desired pressure,
The plasma generation means includes a slot antenna having a conductor formed with a slot for emitting an electromagnetic wave, and an AC power supply for supplying power to the slot antenna, and the slot antenna can generate plasma even at a low power supply frequency. A plasma processing apparatus having a shape having impedance.