JPH11195500A - Surface treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surface treat a large area object uniformly by producing uniform plasma on a wide area using a low UHF band microwave. SOLUTION: A low UHF band microwave generate by a microwave generator 1 is introduced into a cavity resonator 2 by an antenna 13 arranged coaxially with a cylindrical cavity resonator 2 by an electric field coupling method. The microwave resonates in a TM010 mode in the cavity resonator 2, and has complete axial symmetry. The microwave is uniformly radiated to a treatment vessel 3 through plural circular radiation holes 23 axial symmetrically provided in the radiation plate 22 being one part of the cavity resonator 2, gas in the treatment vessel 3 is uniformly formed into plasma, and uniform treatment is conducted on a substrate 30 by the plasma.

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 by using plasma such as dry etching, plasma chemical vapor deposition (plasma CVD), and sputtering.

[0002]

2. Description of the Related Art Processing a surface of an object using plasma is frequently performed when manufacturing a semiconductor device such as an LSI (large-scale integrated circuit) or a display device such as an LCD (liquid crystal display). in use. Plasmas are broadly classified into non-equilibrium plasmas and equilibrium plasmas.
An equilibrium plasma is a plasma in which the temperatures of electrons, ions, and neutral particles (molecules or atoms) constituting the plasma are substantially equal and in a thermal equilibrium state. On the other hand, non-equilibrium plasma is plasma in which the average energy of electrons is larger than the average energy of ions and neutral particles. Non-equilibrium plasma is sometimes referred to as "cold plasma" because the thermal motion of charged particles (electrons and ions) is negligible compared to the motion due to Coulomb force. Non-equilibrium plasma or low-temperature plasma can generate necessary radicals and ions by decomposing a source gas with high-energy electrons. For this reason, it is actively applied to such surface treatments as microfabrication and thin film formation utilizing radicals and ions.

As a method for forming such non-equilibrium plasma or low-temperature plasma, a method using a high frequency has conventionally been adopted. 2. Description of the Related Art As one of surface treatment apparatuses for forming plasma using high frequency, apparatuses using microwaves have been conventionally developed. In this case, as a method of injecting energy into the electrons, a method in which the frequency at which the electrons perform cyclotron motion by the action of a magnetic field is matched with the frequency of the microwave to bring them into a resonance state, and a method of introducing the microwave into the cavity resonator, There is a method of increasing the amplitude. Hereinafter, the latter conventional device related to the present invention will be described.

A conventional example of a surface treatment apparatus using a cavity resonator is disclosed in Japanese Patent Application Laid-Open No. 56-96841. FIG. 5 shows this Japanese Patent Application Laid-Open No. 56-9684.
FIG. 1 is a view showing a conventional surface treatment device disclosed in Japanese Patent Publication No. 1 (JP-A) No. 1; In the surface treatment device disclosed in this publication, the microwave generated by the microwave generator 1 is introduced into the cavity resonator 2 and resonates. Due to the plasma formed by this,
The surface treatment is performed on the substrate 30 mounted on the substrate mounting table 31 in the processing container 3. The processing container 3 has a gas supply port 32.
And an exhaust port 33 are provided. A gas is introduced into the processing vessel 3 and microwave energy is applied to the gas to form the plasma.

In the conventional surface treatment apparatus shown in FIG.
Since plasma is formed inside the cavity 2, the resonance condition of the cavity 2 changes due to the influence of the plasma. As a result, there is a disadvantage that the plasma is unstable. In order to solve this drawback, the following appeared in Japanese Patent Application Laid-Open No. 8-246146 or Japanese Patent Publication No. 8-314.
44. FIG. 6 is a view showing a conventional surface treatment apparatus disclosed in Japanese Patent Publication No. 8-31444 as an example.

In the surface treatment apparatus shown in FIG. 6, a dielectric plate 41 is provided between the cavity resonator 2 and the processing vessel 3 to divide them. A container flange 34 is provided at the edge of the upper end opening of the processing container 3. The gas supply port 32 is
The container flange 34 is formed. Cavity resonator 2
Is joined to the container flange 34. A seal member 9 such as an O-ring is provided at the joint between the two to perform vacuum sealing.

The periphery of the dielectric plate 41 is held by a metal flange 42. Metal flange 42 and dielectric plate 4
1 is brazed and hermetically bonded. A gap is formed circumferentially between the container flange 34 and the metal flange 42. This gap is formed as a gas reservoir for the gas supplied from the gas supply port 32. The gas supplied from the gas supply port 32 enters the gap and diffuses circumferentially.

A gas diffusion plate 50 is provided below the dielectric plate 41.
Is provided. The inside of the gas diffusion plate 50 is hollow, and 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 via the gas diffusion plate 50.

On the surface of the dielectric plate 41 on the processing vessel 3 side,
A metal plating film 21 is formed. Metal plating film 21
Are patterned in a slit shape having a length of at least half the wavelength of the microwave of 2.45 GHz. Microwaves resonating in the cavity resonator 2 are radiated into the processing container 3 through the metal plating film 21, and plasma is formed in a gas atmosphere in the processing container 3.

[0010]

One of the recent demands for a surface treatment apparatus is to increase a processing area.
This demand arises from the need to increase the number of semiconductor circuit elements produced from one large semiconductor wafer in the case of manufacturing semiconductor elements. In the case of a display device such as an LCD, a large substrate is used to make a display device with a large display screen, and thus a large processing area is required.

In the above-described surface treatment apparatus for generating plasma using microwaves, if the processing area is to be increased, the frequency of the microwave is set to 2.
It is considered that it is preferable to set the frequency lower than 45 GHz. This is based on the following reasons.

The size of the cavity resonator is determined so as to match the area of the processing region. As the processing area increases, the capacitance of the cavity resonator also 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 resonator. In other words, the microwave resonates in a state in which a plurality of peaks of one wavelength or 1.5 wavelength or more are formed in the cavity resonator. When a plasma is generated using a microwave that has a plurality of peaks and resonates, the plasma density tends to be non-uniform. Non-uniform plasma densities result in non-uniform processing on the substrate. Therefore, it is better to use a lower frequency microwave as the processing area becomes larger.

For these reasons, the inventor of the present application has considered that a low UHF band (300 MHz to 1 GHz) having a longer wavelength than the conventional microwave of 2.45 GHz is more advantageous. The inventor of the present application prototyped a device using microwaves in such a band. FIG. 7 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. 7 has a microwave generator 1 for generating a microwave in a low UHF band.
The microwave generated by the microwave generator 1 is introduced into the cavity resonator 2 via the coaxial line 11 and the loop 12. More specifically, the loop 12 introduces microwaves into the cavity 2 by a magnetic field coupling method. That is, a magnetic field is circumferentially induced in the cavity 2 by the current flowing through the loop 12. Then, an electric field is generated in the cavity 2 via the magnetic field, and the electromagnetic field of the microwave resonates in the cavity 2. That is, the magnetic field mediates the coupling of the microwave into the cavity resonator 2.

The processing chamber 3 is connected to the cavity resonator 2 with a dielectric plate 41 interposed therebetween. The processing container 3 has a gas supply system 5 that supplies gas from the gas supply port 32 into the processing container 3. Further, the processing container 3 has an exhaust port 33.
And an exhaust system 6 for exhausting the processing container 3 from the inside. A substrate mounting table 31 is provided in the processing container 3.

The cavity resonator 2 transmits the microwave by TM (trans).
(verse magnetic) A cylindrical resonator that resonates in the ₀₁₀ mode. The axis of the cylinder is the vertical direction on the paper, and
, That is, the axis perpendicular to the center of the substrate 30. If the existence of the loop 12 is neglected, the _TM010 mode generates a substantially uniform plasma in a plane perpendicular to the central axis because the electromagnetic field distribution is completely axisymmetric. By mounting the substrate 30 in parallel with this surface, it is possible to perform substantially uniform processing on the surface of the substrate 30.

Further, in the apparatus shown in FIG.
6 is different from the apparatus shown in FIG. Cavity resonator 2 of dielectric plate 41
On the side, a radiation plate 22 that is the lower wall of the cavity resonator 2 is provided. The radiation plate 22 is a metal plate, and has a plurality of circular holes 23 provided in an axially symmetric manner. The microwave resonating in the cavity resonator 2 passes through the circular hole (hereinafter referred to as “radiation hole”) 23 and passes through the dielectric plate 41 and is radiated into the processing chamber 3. Then, the emitted microwave generates plasma in the processing container 3.

As a result of the study by the inventor, it has been found that the following problems are encountered in the prototype surface treatment apparatus shown in FIG. The electromagnetic field created in the cavity resonator 2 is pure TM
_In the case of the ₀₁₀ mode, it clearly has perfect axial symmetry. However, in the conventional cavity resonator shown in FIG. 7, one excitation loop 12 is attached near the side wall.
The loop 12 disturbs the electromagnetic field in the cavity 2 as much as possible, and furthermore, in order to secure necessary heat resistance and electrical coupling, a plate-like member having a thickness of about 2 mm and a width of about 15 mm is formed into a loop. It is made by molding.

However, the presence of the loop 12 causes a problem that the electromagnetic field in the cavity 2 is locally disturbed as shown in FIG. 8 and loses complete axial symmetry. FIG. 8 is a diagram showing this problem, and is a schematic diagram showing the resonance of the _TM010 mode magnetically coupled in the device of FIG. 8A is a sectional view in the axial direction of the cavity resonator 2, and FIG. 8B is a sectional view in a direction perpendicular to the axis. FIG. 8 shows a state of an electromagnetic field in the cavity resonator 2 at a certain moment. In FIG. 8, E is an electric field,
H indicates a magnetic field, and i indicates a current. The electric field E is parallel to the central axis of the cavity 2 and the magnetic field H is coaxial and circumferential about the central axis. Then, at a certain moment, the current i
Flows radially from the center of the bottom surface of the cavity 2 toward the periphery, flows upward on the side surface, and then flows toward the center on the upper surface.

As shown in FIG. 8 (particularly (B)), in the device shown in FIG. 7, the axial symmetry of the electromagnetic field is disturbed near the loop 12. This is clear from the following experimental results. That is, when the substrate 30 was etched by the conventional apparatus shown in FIG. 7, it was found that the etching rate immediately below the position where the loop 12 was located was about 5% higher than the etching rate of the other parts. Further, when the loop 12 was moved from the position shown in FIG. 8 to the opposite side by 180 degrees around the center axis, the rising portion of the etching rate also moved to the opposite side by 180 degrees. This result is interpreted that the plasma density in the processing chamber 3 is asymmetrical due to the asymmetry of the electromagnetic field in the cavity resonator 3 due to the presence of the loop 12.

The invention of the present application has been made to solve the above-mentioned problem, and generates a uniform plasma over a wide area by using a microwave in a low UHF band to uniformly apply an object over a large area. It is an object of the present invention to provide a practical device capable of performing various surface treatments.

[0022]

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 generating means for generating microwaves in a low UHF band of GHz, a cavity formed so that the microwaves generated by the microwaves resonate in the _TM010 mode, and a microwave generating means. Microwave introduction means for introducing the microwave into the cavity resonator;
An airtight processing container connected to the cavity resonator so that microwaves are radiated from the cavity resonator, and a gas supply system for supplying a gas that is turned into plasma by the emitted microwave energy into the processing container. Means for arranging the object to be processed at a position to be processed by the plasma, wherein the microwave introduction means has an antenna arranged coaxially with the center axis of the cavity resonator, and from this antenna It has a configuration in which microwaves are excited by an electric field coupling method and are introduced into the cavity resonator. According to a second aspect of the present invention, in order to solve the above problem, in the configuration of the first aspect, the processing target is a circular substrate, and the holding means is the cylindrical cavity resonator. This substrate is held at a position coaxial with the substrate. Further, in order to solve the above problem, the invention according to claim 3 is:
In the configuration of the first or second aspect, the cavity has a configuration of a reentrant type. Further, in order to solve the above problem, the invention described in claim 4 is:
In the configuration of the above-mentioned claim 1, 2 or 3, a dielectric plate for transmitting microwaves is provided between the cavity resonator and the processing container, and both are partitioned.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described. FIG. 1 is a front view showing a surface treatment apparatus according to an embodiment of the present invention, and FIG. 2 is a schematic view showing an electromagnetic field distribution in the cavity resonator shown in FIG. The surface treatment apparatus shown in FIG. 1 has a microwave generator 1 for generating a microwave in a low UHF band. The microwave generated by the microwave generator 1 is introduced into the cavity resonator 2 by the microwave introducing means 10. The cavity 2 is an airtight processing container 3
It is connected to the. The processing container 3 has a gas supply system 5 that supplies gas from the gas supply port 32 into the processing container 3.
Further, the processing container 3 has an exhaust system 6 that exhausts the inside of the processing container 3 from the exhaust port 33. The processing container 3 has a substrate mounting table 31 on which the substrate 30 is mounted.

As the microwave generator 1, a solid-state element is usually adopted, and the frequency is in a low UHF band, for example, 500 MHz.
It is. Specifically, a field effect transistor (FET)
Can be used. As such a solid-state element, for example, MRF-393 manufactured by Motorola is commercially available. The output of the microwave generator 1 is about 2 kW
It is said.

The microwave introducing means 10 includes a coaxial line 11 connecting the microwave generator 1 and the cavity resonator 2 and an antenna 13 provided at a portion where the coaxial line 11 is connected to the cavity resonator 2. It is mainly composed. The coaxial line 11
This is a two-wire circuit for transmitting microwaves, and includes an inner conductor and a coaxial outer conductor surrounding the inner conductor. A dielectric is loaded between the inner conductor and the outer conductor as necessary.

The antenna 13 is configured to introduce microwaves into the cavity 2 by an electric field coupling method. The antenna 13 is provided by extending the inner conductor of the coaxial line 11 and has a round bar shape with an outer diameter of about 17 mm.
The material of the antenna 13 is aluminum, copper, or the like. The antenna 13 slightly protrudes inside from the center opening of the upper wall of the cavity resonator 2. The protrusion length is, for example, about 17 mm.

The microwave transmitted by the coaxial line 11 is introduced into the cavity 2 through an antenna 13 by an electric field coupling method. The antenna 13 is not loop-shaped, and has an open end. Therefore, a microwave electric field is excited into the cavity 2 from the end of the antenna 13. Based on this electric field, a magnetic field is generated circumferentially in the cavity resonator 2, and the electromagnetic field of the microwave resonates in the cavity resonator 2. That is, the electric field from the antenna 13 mediates the coupling of the microwave into the cavity resonator 2.

The cavity resonator 2 is a cylindrical container made of metal such as aluminum or stainless steel. The cavity resonator 2 is a cylindrical resonator in which the microwave generated by the microwave generator 1 resonates in the lowest order _TM010 mode. The resonance frequency f _{0 in} this mode is calculated by the following equation, where a 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. Note that the axial length of the cavity resonator 2 may be approximately the same as the radius a, for example, 175 mm.

FIG. 2 is a schematic diagram showing _TM010 mode resonance excited by electric field coupling in the apparatus shown in FIG. 2A is a sectional view in the axial direction of the cavity resonator, and FIG. 2B is a sectional view in a direction perpendicular to the axis. FIG.
In the equation, E represents an electric field, H represents a magnetic field, and i represents a current. As shown in FIG. 2, T is excited by the electric field coupling method.
In the _M010 mode, the distribution of the electromagnetic field is perfectly axisymmetric,
A uniform plasma with good axial symmetry is formed. This point is significantly different from the magnetic field coupling system shown in FIG.

As shown in FIG. 2A, in the _TM010 mode, the direction of the electric field is the axial direction, and as shown in FIG. 2B, the direction of the magnetic field is the circumferential direction. At a certain moment, the high-frequency current flows from the center to the periphery in the lower plate portion of the cavity resonator 2, flows upward in the side plate portion, and flows from the periphery to the center in the upper plate portion.

Returning to FIG. 1, another structure of the apparatus according to the present embodiment will be described. First, the processing container 3 is connected to the cavity resonator 2 with the dielectric plate 41 interposed therebetween. The dielectric plate 41 is formed of quartz glass or alumina, and may have a thickness of about 30 mm. A radiation plate 22 which is a wall of the cavity 2 is provided on the side of the cavity 2 of the dielectric plate 41. The radiating plate 22 is a metal plate, and has a plurality of radiating holes 23 provided axially symmetrically. The microwave resonating in the cavity resonator 2 passes through the radiation hole 23 and passes through the dielectric plate 41 and is radiated into the processing container 3. Then, the emitted microwave is applied to the processing container 3
Generate plasma inside. The radiation hole 23 has a diameter of 90.
mm from the center axis of the cavity resonator 2.
6 so that the center is located at a radius position of about 0 mm.
About the number is provided.

The processing container 3 has a gas supply port 32 and an exhaust port 33. 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 radiation plate 22. This gap is formed as a gas reservoir for the gas supplied from the gas supply port 32. Gas supply port 32
Is supplied into the gap and diffuses circumferentially.

The above-described dielectric plate 41 has a flange 42 connected to a side surface thereof. This flange 42 is airtightly connected to the container flange 34. A seal member 9 such as an O-ring is provided between the flange 42 and the container flange 34 to form a vacuum seal.

The gas supply system 5 has a pipe 51 for connecting a gas cylinder (not shown) to the gas supply port 32, a valve 52 provided on the pipe 51, and a flow regulator (not shown). The exhaust port 33 is provided on the bottom surface of the processing container 3.
Further, the exhaust system 6 has a vacuum pump such as a turbo molecular pump that exhausts the inside of the processing container 3 from the exhaust port 33. The exhaust system 6 is configured to evacuate the processing vessel 3 from 1 Torr to 10 ^-3.
The pressure can be reduced to about Torr.

The processing vessel 3 is a cylindrical vessel having substantially the same inner diameter as the cavity resonator 2, and is made of a metal such as aluminum or stainless steel. Processing container 3
Substrate mounting table 31 as a holding means for holding substrate 30 to be processed at a position to be processed by plasma is provided at substantially the center of the inside. The substrate 30 is mounted and held on a substrate mounting table 31. The substrate mounting table 31
It is a metal such as stainless steel, and is supported by columns 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 constant bias potential to the substrate 30. The high frequency power supply 7 provided outside the processing container 3 is connected to the substrate mounting table 31. Due to the interaction between the high-frequency voltage provided by the high-frequency power supply 7 and the plasma, a negative bias potential for the plasma is generated in the substrate 30 on the substrate mounting table 31. An insulator 312 is provided so as to cover the substrate mounting table 31 and the column 311, and insulates the substrate mounting table 31 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. An electrostatic chucking mechanism is provided in the substrate mounting table 31 as needed, and electrostatically chucks the substrate 30. While a predetermined gas is supplied into the processing container 3 through the gas supply port 32 by the gas introduction system 5, the processing container 3 is
The inside is evacuated, and the inside of the processing container 3 is maintained at a set pressure. In this state, the microwave generator 1 generates a microwave in the low UHF band. The microwave is transmitted by the coaxial line 11 and introduced into the cavity resonator 2 via the antenna 13.

The microwaves are radiated into the processing vessel 3 through the radiation holes 23 of the radiation plate 22 while resonating in the cavity cavity 2 in the _TM010 mode. The emitted microwave
Plasma is formed by injecting the energy into the gas supplied into the processing chamber 3. Then, a desired process is performed on the surface of the substrate 30 using the plasma. For example, when performing plasma reactive ion etching,
A gas for generating an active species, for example, a fluorine-based active species is supplied in the plasma, and the substrate 30 is etched with the active species. In the case of performing plasma CVD, a source gas that causes a decomposition reaction in plasma is supplied to deposit a desired 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 ions incident on the substrate 30, is usually 20 to 30 V
It is about. In this case, the substrate 30 is
When a negative self-bias voltage is generated, ions are extracted from the plasma, and the collision with the substrate 30 is promoted. Such a configuration is suitable for reactive ion etching requiring relatively large energy.

In the above operation, the upper surface of the substrate mounting table 31 is parallel to the radiation plate 22 as shown in FIG. Therefore, the electric field between the radiation plate 22 and the substrate mounting table 31 is perpendicular to the substrate 30. For this reason,
Many ions in the plasma are vertically incident on the substrate 30.
This point is particularly suitable, for example, when it is necessary to allow a large amount of ions to reach the bottom of a groove or hole formed on the surface of the substrate 30. In addition, since the electric field to the substrate becomes vertical in combination with the uniformity of the plasma in the circumferential direction, the substrate 3
The amount of incident ions at zero becomes uniform in the circumferential direction. The parallel relationship between the upper surface of the substrate mounting table 31 and the radiation plate 22 also contributes to such uniform processing of the substrate 30.

FIG. 3 is a diagram showing the results of an experiment confirming the effects of the apparatus of the present embodiment shown in FIGS. 1 and 2. In this experiment, plasma etching was performed as an example of the surface treatment. Then, the distribution of the etching rate in the circumferential direction at a position having a radius of about 75 mm from the center of the substrate 30 was measured. In FIG. 3, the line plotted by ○ is the etching rate distribution in the apparatus of the present embodiment shown in FIG. 1, and the line plotted by X is the etching rate distribution in the apparatus of the prototype shown in FIG.

As shown in FIG. 3, in the apparatus shown in FIG. 7, the variation in the etching rate at the position in the circumferential direction is large, and it can be seen that uniform etching cannot be performed. On the other hand, FIG.
It can be seen that in the apparatus described above, the etching rate is uniform at the circumferential position, and uniform etching can be performed.

Next, another embodiment of the present invention will be described. FIG. 4 is a front view showing a surface treatment apparatus according to another embodiment of the present invention. In the embodiment shown in FIG.
A re-entrant type cavity resonator 2 is used. The reentrant cavity resonator 2 is obtained by cutting the center conductor of a coaxial resonator, and its resonance frequency can be adjusted by the length of the center conductor 25 (L1 and L2 in FIG. 4).

As described above, since the size of the cavity resonator 2 is an important parameter as a condition for determining the resonance frequency, if the resonance frequency is fixed, the size of the cavity resonator is also fixed accordingly. Will be done. The size of the cavity resonator 2 determines a region where plasma is formed. On the other hand, the size of the cavity resonator 2 depends on the substrate 30 to be processed.
Is limited by the size of Substrate 3 with cavity resonator 2
If the resonance frequency is designed to be equal to 0, the resonance frequency of the cavity resonator 2 may deviate from a desired frequency. The oscillating frequency of the microwave generator 1 may also be limited, and it is necessary to match the resonance frequency to such an oscillating frequency.

The embodiment shown in FIG. 4 has been made in consideration of such circumstances. 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 generator 1 is increased. In particular,
An upper conductor 25 is provided so as to surround the periphery of the antenna 13 protruding into the cavity resonator 2. The upper conductor 25 has a cylindrical shape coaxial with the antenna 13 and is made of the same metal as the material of the cavity resonator 2. A lower conductor 26 is provided at the center of the radiation plate 22 forming the lower wall of the cavity resonator. The lower conductor 26 is connected to the antenna 13
It is a columnar shape (the interior may be hollow) provided coaxially, and the material is the same metal as the cavity resonator 2.

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 total length (L1 + L2) of the upper conductor 25 and the lower conductor 26 is 100 mm, and The thickness (outer diameter) of the lower conductor 26 is about 70 mm. Note that the antenna 13 projects slightly (about 17 mm) from the lower end of the upper conductor 25. With such a configuration, an optimum resonance state can be obtained.

As described at the outset, the present invention is used when a surface reaction is advanced using non-equilibrium plasma, so-called low-temperature plasma. However, the present invention is not limited to this, and other plasmas may be used. It is needless to say that the present invention is also effective when the surface treatment is performed.

The substrate 30 to be processed is not limited to a circular shape, but may be a rectangular shape such as a liquid crystal substrate. In the case of a rectangular substrate, a cavity 2 having a diameter equal to or greater than the diagonal of the square is used, and the center of the substrate and the central axis of the cavity 2 are also aligned. . It is needless to say that a substrate having a shape other than a circular or square shape and a shape other than a plate shape may be used as an object to be processed.

[0049]

As described above, according to the invention of claim 1 of the present application, since a microwave in the low UHF band is used, a uniform surface treatment can be performed even when the treatment area becomes large. The use of the cavity resonator that resonates in the _TM010 mode enables more uniform surface treatment. The cavity resonator is excited by an electric field coupling method having perfect axial symmetry, which contributes to uniform surface treatment with uniform plasma. According to the second aspect of the present invention, in addition to the effects of the first aspect of the present invention, an optimum configuration is obtained when the object to be processed is a circular substrate such as a semiconductor wafer. According to the third aspect of the present invention, in addition to the effects of the first or second aspect, the size of the cavity and the oscillation frequency of the microwave generator are set because the cavity is of the reentrant type. The degree of freedom increases. Further, according to the invention of claim 4, according to claim 1, 2, or 3,
In addition to the effect of the above, the cavity is separated from the processing vessel, and plasma is generated in a different place from the inside of the cavity.
Changes in resonance conditions due to the presence or absence of plasma can be reduced.

[Brief description of the drawings]

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

FIGS. 2A and 2B are schematic views showing resonance in the electric field-coupled TM ₀₁₀ mode in the apparatus shown in FIG. 1, wherein FIG. 2A is an axial cross-sectional view of a cavity resonator 2, and FIG. FIG.

FIG. 3 is a diagram showing the results of an experiment confirming the effects of the device of the present embodiment shown in FIGS. 1 and 2.

FIG. 4 is a front view showing a surface treatment apparatus according to another embodiment of the present invention.

FIG. 5 is a view showing a conventional surface treatment apparatus disclosed in Japanese Patent Application Laid-Open No. 56-96841.

FIG. 6 is a view showing a conventional surface treatment apparatus disclosed in Japanese Patent Publication No. 8-31444.

FIG. 7 is a front view showing the structure of a conventional surface treatment apparatus prototyped by the inventor using microwaves in the low UHF band.

8A and 8B are schematic diagrams showing _TM010 mode resonance magnetically coupled in the device of FIG. 7, in which FIG. 8A is an axial cross-sectional view of the cavity resonator 2, and FIG. 8B is a direction perpendicular to the axis. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Microwave generator 10 Microwave introduction means 11 Coaxial line 13 Antenna 2 Cavity resonator 22 Radiation plate 23 Radiation hole 25 Central conductor 3 Processing container 30 Substrate 31 Substrate mounting table as holding means 311 Support 312 Insulator 32 Gas supply Port 33 exhaust port 34 container flange 41 dielectric plate 42 metal flange 43 mounting flange 5 gas supply system 51 piping 52 valve 6 exhaust system 7 high frequency power supply 9 sealing member

──────────────────────────────────────────────────の Continuation of the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/3065 H01L 21/31 C 21/31 21/302 B (72) Inventor Kim Keiyo 5-8 Yotsuya, Fuchu-shi, Tokyo No. 1 Anelva Co., Ltd. (72) Inventor Tsutomu Tsukada 5-7-1 Yotsuya, Fuchu-shi, Tokyo Anelva Co., Ltd.

Claims (4)

[Claims] 1. A microwave generating means for generating a microwave in a low UHF band from 300 MHz to 1 GHz, and a microwave generated by the microwave generating means is _TM010.
A cylindrical cavity formed so as to resonate in a mode, microwave introduction means for introducing microwaves generated by microwave generation means into the cavity, and microwaves from the cavity. An airtight processing container connected to the cavity resonator so that it is radiated, a gas supply system that supplies a gas that is turned into plasma by the emitted microwave energy into the processing container, and a position where the plasma is used for processing. Holding means for holding the object to be processed, the microwave introduction means has an antenna arranged coaxially with the center axis of the cavity resonator, from this antenna microwaves by the electric field coupling method A surface treatment apparatus characterized by being excited and introduced into a cavity resonator. 2. The processing object is a circular substrate,
2. A surface treatment apparatus according to claim 1, wherein said holding means holds the substrate at a position coaxial with the cylindrical cavity resonator. 3. The surface treatment apparatus according to claim 1, wherein the cavity resonator is of a reentrant type. 4. A microwave-transmitting dielectric plate is provided between the cavity resonator and the processing container, and the dielectric plate is partitioned between the cavity resonator and the processing container.
The surface treatment apparatus as described in the above.