JPH10298786A - Surface treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical device capable of executing uniform surface treatment of an object of a large area, by using microwaves of a low UHF zone. SOLUTION: Microwaves of a low UHF zone generated by a microwave generator 1 are resonated in a TM010 mode in a hollow resonator 2, microwaves are radiated into a treating vessel 3 through plural circular radiating holes 23 provided axially symmetrically on a radiating board 22 which is a part of the hollow resonator 2, a gas in the treating vessel 3 is converted into plasma by the microwaves, and prescribed treatment is executed to a substrate 30 as an object by the plasma. Each radiating hole 23 is provided with a cover board made of dielectrics airtightly clogging each radiating hole 23 and maintains the airtightness of the treating vessel 3 while the microwaves are transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface treatment apparatus for performing a predetermined treatment on the surface of an object using plasma.
For example, the present invention relates to a surface treatment apparatus used when manufacturing a semiconductor element such as dry etching, CVD, and sputtering.

[0002]

2. Description of the Related Art Performing a predetermined process on the surface of an object using plasma is frequently used for manufacturing a semiconductor device such as an LSI (large-scale integrated circuit) or a display device such as an LCD (liquid crystal display). It is used. Non-equilibrium plasma, so-called low-temperature plasma, is widely used as a means for efficiently proceeding a surface reaction using chemically active radicals or the like while keeping the temperature of an object low. As a method of generating such low-temperature plasma, a method of generating plasma by using a high frequency has conventionally been adopted.

[0003] As one of the surface treatment apparatuses for generating plasma using high frequency, those using microwaves have been studied and developed. In this case, as a method of supplying energy to the electrons, a method in which the frequency at which the electrons perform cyclotron motion by the action of a magnetic field matches the frequency of the microwaves to bring them into a resonance state, and a method of introducing the microwaves into the cavity resonator To increase the amplitude. Hereinafter, the prior art will be described with respect to the latter device related to the present invention.

A conventional surface treatment apparatus using a cavity resonator is disclosed in Japanese Patent Application Laid-Open No. 56-96841. FIG. 8 shows this Japanese Patent Application Laid-Open No. 56-9684.
FIG. 1 is a view showing the structure of a conventional surface treatment apparatus disclosed in Japanese Patent Publication No. 1-No. In the surface treatment apparatus disclosed in this publication, the microwave generated by the microwave generator 1 is introduced into the cavity resonator 2 to resonate, and the plasma generated thereby causes
A predetermined surface treatment is performed on the substrate 30 mounted on the substrate mounting table 31 in the processing container 3. The processing container 3 is provided with a gas supply port 32 and an exhaust port 33. A gas having a predetermined pressure is introduced into the processing container 3, and the gas is used to generate the plasma to perform a predetermined process. Has become.

However, in the conventional surface treatment apparatus shown in FIG. 8, since the plasma is generated inside the cavity 2, the resonance condition of the cavity 2 changes depending on the presence or absence of the plasma. Has the disadvantage of being unstable. The next issue to solve this shortcoming was
JP-A-8-246146 or JP-B-8-31
No. 444. FIG. 9 is a view showing the structure of a conventional surface treatment apparatus disclosed in Japanese Patent Publication No. 8-31444 as an example.

In the surface treatment apparatus shown in FIG. 9, a dielectric plate 41 is provided between the cavity resonator 2 and the processing container 3 to partition them. At the edge of the upper end opening of the processing container 3,
A container flange 34 as shown in FIG. 9 is provided,
The gas supply port 32 is formed in the container flange 34. The edge of the lower end opening of the cavity resonator 2 is joined to the container flange 34. In addition, a sealing member 9 such as an O-ring is provided at a joint portion between the two to perform vacuum sealing.

The dielectric plate 41 is formed of a metal flange 4.
2, the metal flange 42 and the dielectric plate 41 are brazed and hermetically joined. A gap is formed circumferentially between the container flange 34 and the metal flange 42. This gap is the gas supply port 32
It is formed as a gas reservoir for the gas supplied from.
That is, the gas supplied from the gas supply port 32 enters the gap and diffuses circumferentially.

[0008] A gas diffusion plate 50 is provided below the dielectric plate 41. The inside of the gas diffusion plate 50 is hollow, and has a configuration in which a number of gas blowing holes (not shown) are uniformly provided so as to face the space in the processing container 3. The gas diffused circumferentially in the gap is blown into the processing vessel 3 through the gas diffusion plate 50.

A metal plating film 21 formed in a predetermined pattern is formed on the surface of the dielectric plate 41 on the processing container 3 side. The metal plating film 21 forms a part of the cavity 2, and microwaves resonating in the cavity 2 are radiated into the processing container 3 through the metal plating film 21, and The gas is turned into plasma. The metal plating film 21 has a shape having a slit having a length of at least half the wavelength of the microwave. Also,
The microwave of 2.45 GHz is used.

[0010]

One of the recent demands for a surface treatment apparatus is to increase the area of a treatment area. This requirement arises, for example, from the need to improve the productivity by increasing the number of devices produced from one wafer using a large wafer in the case of manufacturing semiconductor devices. In the case of a display device such as an LCD, a large substrate is used in order to obtain a large display screen, and a surface treatment device having a large processing area is required.

Here, in the above-described surface treatment apparatus for generating plasma using microwaves, if the treatment area is to be increased, the frequency of the microwaves should be lower than the conventional 2.45 GHz. It is considered preferable. This is based on the following reasons.

That is, since the size of the cavity is determined to match the size of the processing area, the size of the cavity increases as the processing area increases. In this case, in the case of a high-frequency microwave, the wavelength of the microwave becomes relatively shorter than the size of the cavity, and a plurality of peaks having one wavelength or 1.5 wavelength or more are contained in the cavity. The microwaves resonate in a state where is formed. When a plasma is generated using a microwave that has a plurality of peaks and resonates in this manner, the plasma density tends to be non-uniform, and there is a problem in terms of uniform processing. Therefore, it is better to use a lower frequency microwave as the processing area becomes larger.

From the above, the inventor of the present application considers that a low UHF band (300 MHz to 1 GHz) shorter than the above-described conventional microwave of 2.45 GHz is more advantageous, and that such a band is used. A prototype device using microwave was made. FIG. 10 is a front view showing the structure of a surface treatment apparatus prototyped by the inventor using microwaves in the low UHF band.

The surface treatment apparatus shown in FIG. 10 has a microwave generator 1 for generating a microwave in the low UHF band and a microwave generated by the microwave
, A processing vessel 3 connected to the cavity 2 with a dielectric plate 41 interposed therebetween, a substrate mounting table 31 provided in the processing vessel 3, A gas supply system 5 that supplies a predetermined gas into the processing container 3 from a gas supply port 32 provided in the container 3, an exhaust system 6 that exhausts the inside of the processing container 3 from an exhaust port 33 provided in the processing container 3, It is mainly composed of

The cavity resonator 2 is specifically a cylindrical resonator operating in the _TM010 mode. The axis of the cylinder is the vertical direction on the paper. Since the distribution of the electromagnetic field is completely axisymmetric in the _TM010 mode, a substantially uniform plasma can be generated in a plane perpendicular to the central axis, and the substrate 30 is placed parallel to this plane. Thus, the surface of the substrate 30 can be uniformly processed.

The apparatus shown in FIG. 10 differs from the apparatus shown in FIG. 9 in that the microwave is radiated from the cavity resonator 2 to the processing vessel 3. That is, the cavity resonator 2 of the dielectric plate 41
On the side, a radiation plate 22 constituting the wall of the cavity resonator 2 is provided. The radiating plate 22 is a metal plate.
As shown in FIG. 5, the shape is such that a plurality of circular holes 23 are provided in an axially symmetric manner. The microwave resonating in the cavity resonator 2 passes through the circular hole (hereinafter referred to as a radiation hole) 23 and passes through the dielectric plate 41 and is radiated into the processing vessel 3, and the gas in the processing vessel 3 is emitted. Is turned into plasma.

The inventors of the present invention have found that the conventional surface treatment apparatus shown in FIG. 9 and the prototype surface treatment apparatus shown in FIG. 10 have the following problems. That is,
As described above, when processing a large-area substrate 30 as an object, the size of the cavity resonator 2 increases accordingly. In this case, in the device shown in FIGS. 9 and 10,
Increasing the size of the cavity resonator 2 leads to increasing the size of the dielectric plate 41 that separates the cavity 2 from the processing chamber 3. For example,
When the diameter of the substrate increases to about 300 mm,
The processing container 3 also needs to be cylindrical with an inner diameter of about 400 mm. In this case, the dielectric plate 41 also has a disk shape with a diameter of about 400 mm.

Here, since the inside of the processing vessel 3 is evacuated by the exhaust system 6 to be in a vacuum and the inside of the cavity resonator 2 remains at the atmospheric pressure, a force due to this pressure difference is applied to the dielectric plate 41. become. In this case, when the diameter becomes about 400 mm, it is necessary to use a dielectric plate 41 having a thickness of about 30 mm to withstand the pressure difference. However, when such a thick dielectric plate 41 is used, the rate at which microwaves radiated from the cavity resonator 2 are attenuated when passing through the dielectric plate 41 increases, and the plasma generation efficiency (input microwave frequency) increases. Ratio of plasma density generated to electric power)
Is reduced.

When the dielectric plate 41 becomes large,
The problem of the heat resistance of the brazed portion between the dielectric plate 41 and the metal flange 42 also becomes apparent. That is, the brazing portion between the dielectric plate 41 and the metal flange 42 is 1000
Heated to about ° C. Further, when plasma is generated in the processing chamber 3, the plasma is also heated by heat from the plasma. In this case, since the coefficient of thermal expansion is different between the dielectric plate 41 and the metal flange 42, the area of the brazed portion increases as the size of the dielectric plate 41 increases, and the difference in the amount of thermal expansion between the two increases. As a result, there is a problem that the brazed portion is peeled off or a gap is formed, and the vacuum seal is damaged. To prevent this, it is necessary to increase the amount of brazing material and braze it carefully, but if too much brazing material is used, the thermal stress on the dielectric plate 41 increases and the dielectric material 4
Cracking may occur, and the difficulty of brazing work increases.

The invention of the present application has been made to solve such a problem, and a uniform plasma is generated in a large area by using a microwave in a low UHF band, so that an object having a large area can be formed. It is an object of the present invention to provide a practical device capable of performing a uniform surface treatment.

[0021]

Means for Solving the Problems In order to solve the above problems, the invention described in claim 1 of the present application is to increase the frequency from 300 MHz to 1 MHz.
A microwave generator for generating microwaves in the low UHF band of GHz, a cavity resonator in which the microwaves generated by the microwave generator are coupled to resonate in the _TM010 mode, and connected to the cavity resonator A hermetically sealed processing container, a gas supply system for supplying a predetermined gas into the processing container, and an exhaust system for exhausting the inside of the processing container, and the microwave inside the processing container is radiated from the cavity resonator. Gas into plasma,
In a surface treatment apparatus that performs a predetermined treatment by plasma on an object placed in a treatment container, a part of the cavity resonator is configured by a radiation plate disposed at a portion where the treatment container is connected. The radiation plate has a plurality of circular radiation holes provided symmetrically with respect to the axis of the cavity resonator, and microwaves are radiated from the holes toward the processing container. Further, each of the plurality of radiation holes has a configuration in which a dielectric cover plate for hermetically closing the radiation holes is provided. Further, in order to solve the above-mentioned problems, the invention according to claim 2 is based on claim 1.
Has a configuration in which the cavity resonator is of a reentrant type. Also, in order to solve the above problems,
According to a third aspect of the present invention, in the configuration of the first or second aspect, the distance from the central axis of the cavity to the center point of the plurality of radiation holes is 70 ± 10% of the radius of the cavity. It has a configuration that is within the range. Further, in order to solve the above-mentioned problem, the invention according to claim 4 is based on claims 1 and 2
Or in the configuration of 3, for each of the plurality of radiation holes,
A configuration is provided in which a metal adjustment plate is provided to close a part of the radiation hole and adjust the degree of microwave coupling between the cavity resonator and the processing container.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. FIG. 1 is a front view showing the structure of the surface treatment apparatus according to the embodiment of the present invention, and FIG. 2 is a plan view illustrating the configuration of a radiation plate of the apparatus shown in FIG.

The surface treatment apparatus shown in FIG. 1 is, like the apparatus shown in FIG. 9, a microwave generator 1 for generating a microwave in the low UHF band, and a microwave generated by the microwave generator 1 being a coaxial line. Cavity resonator 2 coupled via
An airtight processing container 3 connected to the cavity resonator 2, a substrate mounting table 31 provided in the processing container 3,
A gas supply system 5 for supplying a predetermined gas into the processing vessel 3 from a gas supply port 32 provided in the processing vessel 3, and an exhaust system 6 for exhausting the inside of the processing vessel 3 from an exhaust port 33 provided in the processing vessel 3. Is configured.

As the microwave generator 1, a magnetron is often used, and the frequency is in a low UHF band, for example, 500M.
Hz. The output is about 2 kW. The coaxial line 11 is a two-wire circuit for transmitting microwaves, and is formed from an inner conductor and a coaxial outer conductor surrounding the inner conductor. A dielectric is filled between the inner conductor and the outer conductor as necessary. Note that a coupling loop 12 is provided at a portion connected to the cavity resonator 2, and the microwave is coupled to the cavity resonator 2 via the coupling loop 12.

The cavity resonator 2 is a cylindrical container formed of a metal such as aluminum or stainless steel. The cavity resonator 2 is a cylindrical resonator configured so that the microwave generated by the microwave generator 1 resonates in the lowest order _TM010 mode. The resonance frequency of this mode is a
Is calculated by the following formula, where is the cavity radius. λ ₀ = 2.61a = c / f _{0 From} this equation, when a = 200 mm, f ₀ = 575 MH
z. Here, c is the speed of light in vacuum, and λ ₀ is the wavelength of the microwave.

FIG. 3 is a diagram for explaining _TM010 mode resonance. 3A is a cross-sectional view in the axial direction of the cavity resonator 2, and FIG. 3B is a cross-sectional view in a direction perpendicular to the axis. In FIG. 3, E represents an electric field, H represents a magnetic field, and i represents a current. As shown in FIG. 3, in the _TM010 mode, the distribution of the electromagnetic field is axially symmetric, and uniform plasma with good axial symmetry is formed.

As shown in FIG. 3A, TM ₀₁₀
In the mode, the direction of the electric field is the axial direction, and the direction of the magnetic field is the circumferential direction as shown in FIG. At a certain moment, the high-frequency current flows radially from the center to the periphery in the lower plate portion of the cavity resonator, then flows upward in the side plate portion, and then flows in the upper plate portion from the periphery to the center. .

A radiation plate 22 is provided at a portion of the cavity resonator 2 on the processing container 3 side as described above. This radiating plate 22 has a circular radiating hole 23 as in the device shown in FIG.
Are axially symmetrically provided. Specifically, as shown in FIG. 2, six radiation holes 23 are provided on the circumference concentric with the central axis. However, it is not necessary to be limited to six pieces.
Or 12 pieces may be used. Each radiation hole 23 radiates a microwave resonating in the cavity resonator 2 to the processing container 3. Since the diameter of each radiation hole 23 is at most the radius of the cavity 2 or less, it is at most 1/4 wavelength.

The formation position of the radiation hole 23 is important from the viewpoint of microwave generation efficiency. In the case of the cylindrical cavity resonator 2 operating in the _TM010 mode, the circumferential magnetic field is maximum at about 70% of the cavity radius from the central axis. Therefore,
It is preferable that the center point of the radiation hole 23 is within a range of 70 ± 10% of the radius of the cavity resonator 2 from the central axis of the cavity resonator 2 in terms of plasma generation efficiency.

The radiation hole 23 is provided with a dielectric cover plate 43 for hermetically closing the radiation hole 23. Cover plate 4
The configuration of No. 3 will be described with reference to FIG. FIG.
FIG. 2 is a front sectional view illustrating a configuration of a lid plate 43 mounted on the apparatus of FIG. 1. As can be seen from FIG. 2, the cover plate 43 is a circular plate, and is made of quartz glass, alumina, or the like. The cover plate 43 has a diameter slightly smaller than the diameter of the radiation hole 23 and is mounted on the radiation plate 22 by a mounting flange 44 as shown in FIG. The mounting flange 44 is made of metal such as aluminum or stainless steel, and is brazed to a side end surface of the cover plate 43. The upper end portion of the mounting flange 44 has a flange-like shape bent outward.

On the other hand, a step is provided at the edge of the radiation hole 23 as shown in FIG. 4, and a flange-shaped portion of the mounting flange 44 is placed on the step. Then, the lid plate 43 is held by the radiating plate 22 via the mounting flange 44 by pressing the flange-shaped portion against the radiating plate 22 with a force due to a pressure difference. Note that a seal member 9 such as an O-ring is provided between the flange-shaped portion of the mounting flange 44 and the radiation plate 22. The seal member 9 achieves vacuum sealing of the radiation hole 23.

Next, returning to FIG. 1, another configuration of the apparatus of this embodiment will be described. The processing container 3 is provided with a gas supply port 32 and an exhaust port 33 as in the apparatus shown in FIG. A container flange 34 is provided at the edge of the upper opening of the processing container 3, and the gas supply port 32 is formed in the container flange 34.

As shown in FIG. 1, a gap is formed between the container flange 34 and the end face of the radiation plate 22. The gap is formed as a gas reservoir for the gas supplied from the gas supply port 32, and the gas supplied from the gas supply port 32 enters the gap and diffuses circumferentially. Further, a flange portion 24 is formed on the side surface of the cavity resonator 2, and the flange portion 24 is
Connected to the airtight. That is, a sealing member 9 such as an O-ring is provided between the flange portion 24 and the container flange 34.
Are provided to achieve a vacuum seal.

The gas supply system 5 includes a pipe 51 for connecting a gas bottle (not shown) and the gas supply port 32, a valve 52 provided on the pipe, a flow controller (not shown), and the like. The exhaust port 33 is provided on the bottom surface of the processing container 3. The exhaust system 6 that exhausts the inside of the processing container 3 from the exhaust port 33 is configured by an exhaust system provided with a vacuum pump such as a turbo molecular pump, and can exhaust the inside of the processing container 3 to a pressure of about 1 to 10 ⁻³ Torr. It has become.

The processing vessel 3 is a cylindrical vessel having substantially the same inner diameter as the cavity resonator 2, and is made of metal such as aluminum or stainless steel. A substrate mounting table 31 on which a substrate 30 to be processed is mounted is provided substantially at the center of the processing container 3. The substrate mounting table 31 is made of metal such as stainless steel, and is supported by a support 311. The column 311 penetrates the bottom surface of the processing container 3 in an airtight manner.

The substrate mounting table 31 also functions as an electrode for applying a predetermined bias potential to the substrate 30. That is, the substrate mounting table 31 is connected to a high frequency power supply 7 provided outside the processing chamber 3, and the substrate mounting table 31 is interacted with the high frequency voltage supplied by the high frequency power supply 7 and the plasma.
A negative bias potential is applied to the substrate 30 above the plasma. Note that an insulator 312 is provided so as to cover the substrate mounting table 31 and the columns 311, and is insulated from the processing container 3 that is grounded.

Next, the operation of the apparatus shown in FIG. 1 will be described. The substrate 30 is carried into the processing container 3 through a gate valve (not shown) provided in the processing container 3, and is mounted on the substrate mounting table 31. Note that an electrostatic chucking mechanism is provided in the substrate mounting table 31 as needed, and electrostatically sucks the substrate 30. While supplying a predetermined amount of gas into the processing vessel 3 through the gas supply port 32 by the gas introduction system 5, the inside of the processing vessel 3 is exhausted by the exhaust system 6, and the inside of the processing vessel 3 is maintained at a predetermined pressure.
In this state, the microwave generator 1 operates to generate a microwave in the low UHF band. Microwave is coaxial line 11
And is coupled to the cavity resonator 2.

The microwaves are radiated into the processing vessel 3 through the radiation holes 23 of the radiation plate 22 closed by the cover plate 43 while resonating in the cavity mode 2 in the _TM010 mode. The emitted microwave gives the energy to the gas supplied into the processing container 3, and the gas is turned into plasma to generate plasma. Then, a predetermined process is performed on the surface of the substrate 30 by the action caused by the plasma. For example, when performing plasma etching, a gas for generating an active species such as a fluorine-based active species in plasma is supplied, and the etching is performed by causing the active species to act on the substrate 30. When plasma CVD (chemical vapor deposition) is performed, a source gas that causes a decomposition reaction or the like in plasma is supplied to deposit a predetermined thin film on the substrate 30.

In the low-temperature plasma as in this embodiment, the electron temperature of the plasma is low, and the plasma potential, which is the acceleration voltage of the ions incident on the substrate 30, is usually 20 to 3 times.
It is about 0V. In this case, when the high-frequency power supply 7 is operated to apply a bias voltage to the substrate 30, ions are extracted from the plasma and are likely to collide with the substrate 30. This is suitable for the case of reactive ion etching or the like that requires relatively large energy.

In the operation described above, the substrate mounting surface of the substrate mounting table 31 is parallel to the radiation plate 22 as shown in FIG. For this reason, the electric field between the radiation plate 22 and the substrate mounting table 31 becomes perpendicular to the substrate 30, and the amount of ions incident on the substrate 30 becomes uniform. This configuration also contributes to uniform processing of the substrate 30.

In the above-described apparatus according to the present embodiment, as shown in FIG. 9, the entire boundary surface between the cavity resonator 2 and the processing vessel 3 is not isolated by the dielectric plate 41, but is radiated by the cover plate 43. By hermetically closing the 22 radiation holes 23, airtight isolation between the cavity resonator 2 and the processing vessel 3 is achieved. In this configuration, each cover plate 43 can be made considerably smaller than the dielectric plate 41 shown in FIG. Therefore, the mechanical strength required for each lid plate 43 is considerably lower than that of the dielectric plate 41 shown in FIG. 9, and the thickness can be considerably reduced.

For example, when the cavity resonator 2 has an inner diameter of 400
mm, one cover plate 43 has a diameter of 100 mm.
About 7 mm is enough. Accordingly, the attenuation of the microwave when passing through the cover plate 43 is considerably smaller than that of the dielectric shown in FIG. 9, and the plasma generation efficiency is greatly improved. As a specific improvement example, when the output of the microwave generator 1 is 2 kW, the ion current density in the plasma is about 20 mA / cm ^2, which is about 10% higher than the prototype shown in FIG. 9. Value.

As another effect, when the cover plate 43 is brazed to the mounting flange 44, the area of the brazed portion and the difference in the amount of thermal expansion are considerably smaller than those in FIG. For this reason,
Problems such as peeling and leakage of the brazed portion due to the difference in the amount of thermal expansion are also reduced, and the brazing operation becomes very easy.

Next, another embodiment of the present invention will be described. FIG. 5 is a front sectional view illustrating the configuration of the cover plate 43 in the device according to the second embodiment of the present invention. FIG.
In the embodiment shown in FIG. 7, the mounting flange 44 is not used, and the cover plate 43 is mounted in a state of being simply fitted into the radiation hole 23. That is, the radiation hole 23 of the radiation plate 22 has a step having a size adapted to the outer diameter of the cover plate 43, and the cover plate 43 is directly dropped on the step. Note that a seal member 9 is provided between the lid plate 43 and the step to achieve vacuum sealing.

In the embodiment shown in FIG. 5, since the mounting flange 44 is not used, the production is easy and the cost is advantageous. However, when an O-ring is used as the seal member 9, there is a problem that the O-ring is exposed to microwaves through the cover plate 43 and deteriorates. Therefore, the configuration of the embodiment shown in FIG. 5 is suitable when the power of the microwave is small. Alternatively, if a metal member such as a gasket is used as the seal member 9, the above problem is reduced.

FIG. 6 is a front view illustrating the structure of a surface treatment apparatus according to a third embodiment of the present invention. In the embodiment shown in FIG. 6, a reentrant cavity resonator 2 is used. Reentrant cavity resonator 2
Is a shortened central conductor of the coaxial resonator, and its resonance frequency can be adjusted by the length of the central conductor 25 (L1 and L2 in FIG. 6).

As described above, the size of the cavity resonator 2 is an important parameter as a condition for achieving resonance.
If the resonance frequency is fixed, the size of the cavity resonator is also fixed accordingly, and the degree of freedom in design is low.
The size of the cavity 2 determines the area in which the plasma is formed, and is therefore limited by the size of the substrate 30 to be processed. If the size is designed to match the size of the substrate 30, the resonance frequency of the cavity resonator 2 may deviate from a desired value. Also, the microwave generator 1 may have a limited oscillating frequency in some cases, and it is necessary to match the resonance frequency to such an oscillating frequency.

The configuration shown in FIG. 6 is made in view of such circumstances. That is, the resonance frequency can be adjusted by appropriately setting the length of the center conductor 25, and the degree of freedom in designing the size of the cavity resonator 2 and the oscillation frequency of the microwave oscillator 1 is increased, so that more practical use is possible. It is a device. The center conductor 25 is a columnar member and is formed of the same metal as the cavity resonator 2. As an example of specific dimensions, when the inner diameter of the cavity resonator 2 is 350 mm and the oscillation frequency of the microwave generator 1 is 500 MHz, the center conductor 25 has a length (L1 + L2) of 100 mm and a thickness of 70 mm.
Degree, whereby a resonance state can be obtained.

FIG. 7 is a front view showing the structure of a surface treatment apparatus according to a fourth embodiment of the present invention. In the apparatus shown in FIG. 7, for each of the plurality of radiation holes 23, a metal adjustment for adjusting the degree of microwave coupling between the cavity resonator 2 and the processing container 3 by closing a part of the radiation holes 23. A plate 26 is provided.

In the apparatus of each embodiment described above, the microwave resonating in the cavity 2 is radiated to the processing vessel 3 through the radiation hole 23.
This means that the microwaves inside and the microwaves radiated to the processing container 3 are coupled through the radiation holes 23.

Here, when plasma is generated by the microwave radiated into the processing vessel 3, the spatial impedance in the processing vessel 3 changes, and this impedance change is caused by microwave coupling through the radiation hole 23. This also affects the resonance condition in the cavity resonator 2. That is, radiation hole 2
The greater the coupling of the microwaves through 3, the greater the power applied to the processing vessel 3, which increases the plasma generation efficiency. However, if the coupling is large, the resonance condition of the cavity 2 changes depending on the state of plasma generation. The rate at which they do it will also increase.

The magnitude of the microwave coupling through the radiation hole 23 is appropriately set in consideration of such matters. In this case, the adjusting plate 26 of the present embodiment is an effective means for setting the degree of coupling. That is, the apparatus is operated while sequentially preparing the adjusting plates 26 of various sizes and sequentially exchanging them, and measuring the plasma generation efficiency at that time, thereby selecting the degree of coupling that maximizes the plasma generation efficiency. You can do it.

In this embodiment, one circular plate is used as the adjusting plate 26. However, a ring-shaped plate that covers the peripheral portion of each of the radiation holes 23 is provided in each of the radiation holes 23. You may. Further, a plate mechanism that can continuously adjust the size of the aperture used in the aperture of a camera may be adopted. In addition, the present invention,
As described at the beginning, it is used when the surface reaction is advanced using non-equilibrium plasma, so-called low-temperature plasma, but is not limited to this, and when other plasma is used or other surface treatment is performed Needless to say, it is also effective.

[0054]

As described above, according to the first aspect of the present invention, since microwaves in the low UHF band are used,
Even when the processing area becomes large, uniform surface treatment can be performed. Further, since a cavity resonator that resonates in the _TM010 mode is used, a more uniform surface treatment can be performed. Then, the cavity and the processing container are separated from each other, and plasma is generated at a place different from the inside of the cavity. Therefore, a change in resonance condition due to the presence or absence of plasma can be reduced. In addition, microwave coupling between the cavity resonator and the processing chamber is performed through a plurality of axially symmetrically formed circular radiation holes, which also contributes to uniform surface treatment with uniform plasma. . Furthermore, as a dielectric member that balances the transmission of microwaves and the airtightness of the processing container, a lid plate that covers each radiation hole is adopted, so that microwave attenuation in the dielectric portion can be reduced. As a result, practically significant effects such as improvement of the plasma generation efficiency can be obtained. Claim 2
According to the invention, in addition to the effect of the above-mentioned claim 1, since the cavity resonator is of the reentrant type, the degree of freedom in designing the size of the cavity resonator and the oscillation frequency of the microwave generator is increased, so that practical use is possible. It is possible to obtain a simple surface treatment apparatus. Also,
According to the third aspect of the present invention, in addition to the effects of the first or second aspect, the radiation hole is formed at an optimum position, the microwave is efficiently radiated from the cavity resonator to the processing vessel, and the plasma generation efficiency is good. Becomes According to the fourth aspect of the invention, in addition to the effects of the first, second, or third aspect, a part of each radiation hole is closed to adjust the degree of microwave coupling between the cavity resonator and the processing container. Since the metal adjusting plate is provided, the degree of coupling that maximizes the plasma generation efficiency can be easily set.

[Brief description of the drawings]

FIG. 1 is a front view showing a structure of a surface treatment apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view illustrating a configuration of a radiation plate of the device shown in FIG.

3A and 3B are diagrams illustrating _TM010 mode resonance, wherein FIG. 3A is a cross-sectional view in the axial direction of the cavity resonator 2, and FIG. 3B is a cross-sectional view in a direction perpendicular to the axis.

FIG. 4 is a front sectional view illustrating a configuration of a lid plate mounted on the apparatus of FIG. 1;

FIG. 5 is a front sectional view illustrating a configuration of a cover plate in the device according to the second embodiment of the present invention.

FIG. 6 is a front view illustrating the structure of a surface treatment apparatus according to a third embodiment of the present invention.

FIG. 7 is a front view illustrating a structure of a surface treatment apparatus according to a fourth embodiment of the present invention.

FIG. 8 is a diagram showing the structure of a conventional surface treatment apparatus disclosed in Japanese Patent Application Laid-Open No. 56-96841.

FIG. 9 is a view showing a structure of a conventional surface treatment apparatus disclosed in Japanese Patent Publication No. 8-31444.

FIG. 10 is a front view showing the structure of a surface treatment apparatus prototyped by the inventor as using microwaves in the low UHF band.

FIG. 11 is a plan view illustrating a configuration of a radiation plate of the apparatus shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave generator 2 Cavity resonator 22 Radiation plate 23 Radiation hole 25 Center conductor 26 Adjustment plate 3 Processing container 30 Substrate 31 Substrate mounting table 32 Gas supply port 33 Exhaust port 42 Cover plate 43 Mounting flange 5 Gas supply system 6 Exhaust System 7 High frequency power supply 9 Seal member

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // H01L 21/31 H01L 21/302 B (72) Inventor Tomoaki Koide 5-1-1 Yotsuya, Fuchu-shi, Tokyo Anelva Shares In-company (72) Inventor Tsutomu Tsukada 5-1-1 Yotsuya, Fuchu-shi, Tokyo Anelva Co., Ltd.

Claims (4)

[Claims] 1. A microwave generator for generating a microwave in a low UHF band from 300 MHz to 1 GHz, and a microwave generated by the microwave generator are combined to form a T
A cavity resonator that resonates in the _M010 mode, an airtight processing container connected to the cavity resonator, a gas supply system that supplies a predetermined gas into the processing container, and an exhaust system that exhausts the processing container. A surface processing apparatus that converts a gas in the processing container into plasma by microwaves radiated from the cavity resonator and performs a predetermined process on an object disposed in the processing container by the plasma; A part of the resonator is constituted by a radiation plate disposed at a portion where the processing container is connected,
The radiation plate has a plurality of circular radiation holes provided symmetrically with respect to the axis of the cavity resonator, and microwaves are radiated from the holes toward the processing container. The surface treatment apparatus according to claim 1, wherein each of the radiation holes is provided with a dielectric cover plate for airtightly closing the radiation hole. 2. The surface treatment apparatus according to claim 1, wherein said cavity resonator is of a reentrant type. 3. The distance from the central axis of the cavity to the center of the plurality of radiating holes is equal to 70 mm of the radius of the cavity.
3. The surface treatment apparatus according to claim 1, wherein the value is within a range of ± 10%. 4. A metal adjusting plate is provided for each of the plurality of radiation holes, and covers a part of the radiation holes to adjust the degree of microwave coupling between the cavity resonator and the processing vessel. The surface treatment apparatus according to claim 1, 2 or 3, wherein: