JP3233575B2 - Plasma processing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing apparatus which forms an electrostatic field which decays exponentially with distance from an antenna surface by microwaves, thereby generating plasma.

[0002]

2. Description of the Related Art In recent years, a plasma processing apparatus has been used for processing such as film formation, etching, ashing, and the like in a semiconductor product manufacturing process in accordance with high density and high miniaturization of a semiconductor product. , 0.1 to several tens mTorr
A microwave plasma apparatus that generates high-density plasma by combining a microwave and a magnetic field from a ring-shaped coil is used because a plasma can be stably generated even in a high vacuum state having a relatively low pressure of about r. There is a tendency.

Conventionally, as a microwave plasma apparatus of this type, a microwave introduction port is provided in a plasma generation chamber having a magnetic field forming means to form an electron cyclotron resonance cavity, and ions are extracted from the plasma generation chamber to extract semiconductor wafers in the reaction chamber. For irradiating the ion beam to
JP-A-8-13626), or a discharge tube that generates plasma by introducing microwaves has a structure that extends from the direction of microwave introduction toward the sample in a portion beyond the main discharge portion, enabling plasma processing with a large area. (JP-A-59-202635) and the like are known.

However, the apparatus disclosed in Japanese Patent Publication No. 58-13626 has a plasma generating chamber and a reaction chamber, so that not only the entire apparatus becomes large and the cost becomes high, but also the plasma In order to efficiently irradiate the wafer with the electric field, a high voltage of about 1000 V is required.

Further, in an apparatus as disclosed in Japanese Patent Application Laid-Open No. 59-2026353, the lines of magnetic force generated by applying a current to a ring-shaped coil are not perpendicular to the wafer surface but are inclined. The etching state also inclines in the direction of the lines of magnetic force, and vertical etching cannot be performed.

In order to solve these problems, according to the apparatus disclosed in Japanese Patent Application Laid-Open No. 4-361529 by the present inventor, a specific space between a microwave introduction surface and a wafer mounting surface in a reaction chamber is specified. A cavity resonator structure for exciting electron cyclotron resonance was formed here at a distance, and a relatively compact and high-density plasma could be formed.

[0007]

However, in the above-described apparatus, since a magnetic field is required for generating plasma, a magnetic field generating means such as a permanent magnet or an electromagnetic coil must be provided. There is a problem that not only the device itself is relatively large, but also the cost is high.

Further, in the above-described apparatus, a uniform plasma can be generated to some extent over the entire processing region in the case of a relatively small wafer such as a 6-inch wafer. However, when the diameter of the wafer is increased to 8 inches or 12 inches as in today, the electric field in the vicinity of the central portion of the wafer or in the peripheral portion becomes strong, and the electric field distribution becomes uniform over the entire processing region. And the electric field distribution becomes non-uniform, so that in-plane uniformity cannot be expected even in plasma processing.

Therefore, the present inventor has filed an earlier application (Japanese Patent Application No.
No. 248767) has proposed a plasma processing apparatus capable of generating plasma only by microwaves without using a magnetic field. This processing apparatus irradiates an electromagnetic wave from the antenna member toward the inside of the processing container by supplying a microwave to a planar antenna member having a large number of slits arranged to generate an electromagnetic wave, and the electromagnetic energy This dissociates the plasma gas to generate plasma.

According to this, the gas can be dissociated by the action of the electromagnetic wave radiated from the antenna member to form a plasma having a high density to some extent. Since it is impossible to supply a certain amount of power even if a large power is to be supplied, the supplied power is limited. For example, it is necessary to obtain a plasma density of about 7 × 10 ¹⁰ / cm ³ or more. Turned out to be impossible. The reason is that as the power is turned on, the plasma frequency increases and the plasma density also increases, but in general, the relative permittivity of the plasma in the absence of a magnetic field tends to gradually approach zero, and therefore the plasma This is because the radiated electromagnetic wave without being able to apply more than a certain amount of energy to the antenna is reflected with the energy back to the antenna member.

The present invention focuses on the above problems,
It was created to solve this effectively. It is an object of the present invention to provide a plasma processing capable of forming an electric field that exponentially attenuates as the distance from an antenna surface is increased by a microwave and using the electric field to generate plasma.

[0012]

Means for Solving the Problems As a result of intensive studies on the mechanism of plasma generation, the inventor of the present invention has found that when electromagnetic waves are used as a power input mode, the relative dielectric constant of generated plasma gradually becomes zero as described above. There is a limit to the amount of power input from approaching, but the shape of the slit of the antenna member is slightly changed, and instead of electromagnetic waves as the power input mode,
The present invention has been made based on the finding that the input electric power can be greatly increased by utilizing an electrostatic field generated so as to attenuate exponentially as the distance from the antenna surface increases.

According to a first aspect of the present invention, there is provided an airtight processing container having a mounting table for mounting an object to be processed therein, a microwave generator, and a microwave generated by the microwave generator. A waveguide for guiding to the waveguide, a planar antenna member connected to the waveguide and disposed opposite to the mounting table, a number of slits formed in a number of loops in the antenna member, Means for supplying gas into the processing container, wherein the length of the slit is formed in the processing container so as to form an electrostatic field that attenuates exponentially with distance from the antenna surface. And the distance between the slits in the radial direction of the antenna member is set to a length shorter than the guide wavelength of the microwave , and the length of the slit is
Located radially outward from the center of the antenna member
Are set to be slightly larger in sequence according to
The plasma density at the periphery of the material is larger than that at the center
It is configured so that According to a second aspect of the present invention, there is provided an airtight processing container provided with a mounting table for mounting an object to be processed therein, a microwave generator, and a device for guiding microwaves generated by the microwave generator to the processing container. A planar antenna member connected to the waveguide and arranged opposite to the mounting table, a large number of slits formed in the antenna member in a large number of loops, and Means for supplying gas to the processing vessel, wherein the length of the slit is shorter than the guide wavelength of the microwave in order to form an electrostatic field that attenuates exponentially with distance from the antenna surface in the processing container. And the distance between the slits in the radial direction of the antenna member is set to a length shorter than the guide wavelength of the microwave , and
The outermost periphery of the planar antenna member is propagated here.
To convert the microwave to an electrostatic field almost completely
The alignment slit set longer than the slit length of
Formed inside and located inside the alignment slit
The lengths of the slits are all substantially the same .

According to the first aspect of the present invention, as described above, no radio wave is emitted from the antenna member, but instead, the radio wave attenuates exponentially in the processing container as the distance from the antenna surface increases, as described above. An electrostatic field will be formed. The plasma gas is excited and turned into plasma by this electrostatic field. However, unlike the case of the electromagnetic field, the input power amount does not have a limit and more power can be input. Therefore, the density of the generated plasma can be greatly improved, and the plasma density in the processing space can be made uniform. Also, if the length of the slit located on the peripheral edge side from the central portion side of the antenna member is set to be slightly longer, the plasma density on the peripheral edge side is higher than that on the antenna member center side in the plasma forming space. Therefore, in a processing apparatus in which the plasma density at the periphery of the process space tends to decrease as a result of the separation of the plasma formation space from the process space, the plasma density in the process space can be widened. Can be made substantially uniform. According to the second invention, the slits in the respective branch waveguides are formed so as to be parallel to each other, and the length and the distance between the adjacent slits are the same as in the first invention. Therefore, no radio wave is emitted from the antenna member, and instead, an electrostatic field is formed in the processing container such that the static electric field attenuates exponentially as the antenna member moves away from the antenna surface. A similar effect will be exhibited. In the first and second aspects of the present invention, it is preferable that the length of the slit is set to a value within a range of ± 30% of the guide wavelength around a half of the guide wavelength of the microwave. Further, the distance between the slits adjacent to each other in the radial direction of the planar antenna member is preferably set to a length in the range of 5% to 50% of the guide wavelength of the microwave. Also, by forming a dielectric covering the surface of the planar antenna member opposite to the surface facing the object to be processed, the wavelength of the microwave supplied thereto can be shortened to shorten the guide wavelength. preferable.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the plasma processing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG.
FIG. 2 is a sectional view showing an example of the plasma processing apparatus according to the first invention, FIG. 2 is a plan view showing an antenna member used in the processing apparatus shown in FIG. 1, and FIG. 3 is an enlarged plan view of the antenna member shown in FIG. .

In this embodiment, a case where the plasma processing apparatus is applied to a plasma etching apparatus will be described. As shown in the figure, the plasma etching apparatus 2 as a plasma processing apparatus has a processing container 4 in which the side walls and the bottom are formed of a conductor such as aluminum, for example, and the whole is formed in a cylindrical shape. It is configured as a closed processing space S.

In the processing container 4, a mounting table 6 on which, for example, a semiconductor wafer W as an object to be processed is mounted is accommodated on the upper surface. The mounting table 6 is formed, for example, in an approximately columnar shape in which the central portion is made convex and flat with aluminum or the like which has been anodized, and its lower portion is supported by a support table 8 also formed in a columnar shape with aluminum or the like. In addition, the support table 8 is installed on the bottom of the processing container 4 via an insulating material 10.

On the upper surface of the mounting table 6, an electrostatic chuck or a clamp mechanism (not shown) for holding a wafer is provided. The mounting table 6 For example, it is connected to a 13.56 MHz bias high frequency power supply 16. On the support table 8 that supports the mounting table 6, a cooling jacket 18 through which cooling water or the like for cooling a wafer during plasma processing is provided.

A plasma gas supply nozzle 2 made of a quartz pipe for supplying a plasma gas, for example, an argon gas, into the container is provided on a side wall of the processing container 4 as a gas supply means.
For example, a processing gas supply nozzle 22 made of, for example, a quartz pipe for introducing a processing gas, for example, an etching gas, is provided.
4 and 26 through the mass flow controllers 28 and 30 and the on-off valves 32 and 34, respectively.
And a processing gas source 38. As an etching gas as a processing gas, CF ₃ , CHF ₃ , CF ₄ gas, or the like can be used. Further, a gate valve 40 that opens and closes when a wafer is loaded into and unloaded from the inside of the container is provided on the outer periphery of the container side wall.

An exhaust port 42 connected to a vacuum pump (not shown) is provided at the bottom of the container so that the inside of the processing container 4 can be evacuated to a predetermined pressure as required. On the other hand, a flat antenna member 44 for forming an electrostatic field, which is a feature of the present invention, is provided at an upper portion in the processing container 4. Specifically, the planar antenna member 44 is configured as a bottom plate of a radial waveguide box 46 formed of a hollow cylindrical container having a low height, and is supported by the ceiling of the processing container 4 so as to face the mounting table 6. Provided. The waveguide box 46 is formed of a conductive material, for example, aluminum, and its surface is subjected to alumite treatment to improve the durability against plasma. A quartz glass 48 having a thickness of, for example, about 2 mm is hermetically provided as a protective plate over the entire lower surface of the antenna member 44, and protects the antenna member 44 from plasma while maintaining the inside of the conductive box 46 airtight. I have. Instead of the quartz glass 48, a ceramic thin plate or the like may be used as a protective plate.

At the center of the upper surface of the disc-shaped radial waveguide box 46, an outer tube 52A of a waveguide 52 whose other end is connected to a microwave generator 50 of, for example, 2.45 GHz is connected.
The inner cable 52B is connected to the center of the disk-shaped antenna member 44 or is slightly separated therefrom. In the example shown in the figure, the connection is shown.
As the waveguide, a waveguide having a circular or rectangular cross section or a coaxial waveguide can be used. In this embodiment, a coaxial waveguide is used. A sealing member 56 such as an O-ring is interposed in the penetrating portion of the processing vessel ceiling portion 54 of the waveguide 52 to maintain airtightness. At the connection between the waveguide 52 and the conductive box 46, a sealing material 58 made of, for example, a ceramic seal is provided airtight by brazing or the like in the tube, and the inside of the conductive box 46 is maintained in a vacuum state. I have.

The disk-shaped antenna member 44 is made of a disk made of a conductive material having a diameter of, for example, 50 cm and a thickness of 1 mm or less, for example, a copper plate. Starting from a position slightly outward, for example, about several cm away, a number of slits 60 are formed in a number of loops, for example, concentrically, gradually toward the periphery. In the illustrated example, a case where the slit 60 is formed in a concentric shape is shown.
The slit 60 may be formed in a spiral shape as shown in FIG. That is, in FIG. 2 (B), on a large number of loops in which a large number of slits 60 gradually increase from the center of the conductive disk toward the outer periphery, the longitudinal direction is aligned with the loop so that the longitudinal direction is along the loop. They are arranged at predetermined intervals in the width direction. Such a loop is formed as a spiral wound from the center to the outer periphery.

In this embodiment, the length L of each slit 60
Is set to about 1/2 of the guide wavelength of the microwave from the microwave generator 50 and has a width of about 1
mm. Further, the distance S1 between the slits 60 provided adjacent to each other in the radial direction of the antenna member 44 is preferably set to a length shorter than the guide wavelength of the microwave, particularly, in a range of 5% to 50% of the guide wavelength. . A group of slits is formed over the entire surface of the antenna member 44 so as to satisfy such conditions.

The allowable range of the length L of the slit 60 is as follows:
Less than the guide wavelength λ, preferably １ ／ of the guide wavelength.
Is within a range of about ± 30% of the guide wavelength.
If the length L of the slit 60 is too short, an electrostatic field is only partially generated, which is not preferable. On the other hand, if the length L is equal to or longer than the guide wavelength, the efficiency of generating an electrostatic field is undesirably reduced. . Considering the efficiency, の of the guide wavelength is most preferable, and the longer or shorter the wavelength, the lower the efficiency. In particular, when the length L of the slit is longer than the guide wavelength, other modes are superimposed on the electric field distribution, so that the efficiency is further reduced.
If the distance S1 between the slits adjacent to each other in the radial direction of the antenna member is equal to or longer than the guide wavelength of the microwave, the electromagnetic wave oscillates from the plane of the antenna member. Since the oscillation occurs in the direction, the generation efficiency of the electrostatic field is reduced, which is not preferable.
Further, when the distance S1 is set to approximately の of the guide wavelength, the electrostatic fields generated between the slits have opposite phases, which is preferable.

As described above, by strictly defining the slit length and the distance between the slits, when microwaves are passed through the antenna member 44, unlike the technique of the previous application by the present inventor who emitted electromagnetic waves, In the processing space, it is possible to form an electric field that decays exponentially with distance from the antenna surface. For this reason, even if the relative dielectric constant approaches zero due to an increase in the plasma density due to the power supply, further power supply becomes possible.

In this case, the lengths L of the slits 60 formed over the entire surface of the antenna member 44 are made equal to each other so that the slits 60 are formed immediately below the antenna member and attenuate exponentially with distance from the antenna surface. The strength of the electric field may be made uniform in the horizontal direction. However, in order to cause a bias in the strength of the formed electrostatic field, the length of the slit between the center portion and the peripheral portion of the antenna member 44 is reduced. May be slightly changed within the allowable range described above. For example, as shown in an enlarged view in FIG. 3, the length of the slit may be set so as to gradually increase gradually from the center of the antenna member toward the outside in the radial direction,
For example, the length L1 of the slit 60A located at the innermost circumference is (1/2/10) λ (λ: the guide wavelength of the microwave).
Set to about the length, slit 60B located at the outermost circumference
Can be set to a length of about (1 to 4/10) λ. This makes it possible to form a stronger electrostatic field on the peripheral edge than on the center. It is to be noted that a matching slit for converting the microwave propagating here almost completely into an electrostatic field is provided on the outer circumference of the slit and on the outermost circumference of the antenna member so as to improve the antenna efficiency. You may.

On the other hand, in the radial waveguide box 46, a dielectric 62 having a predetermined permittivity is accommodated in order to shorten the wavelength of the microwave supplied to the antenna member to a short guide wavelength. . Al ₂ O ₃ ,
A material having a small dielectric loss such as SiN can be used. Further, the distance D between the lower surface of the antenna member 44 and the upper mounting surface of the mounting table 6 is set to, for example, about 5 to 7 cm.
It is separated into a process region S20 in which processing is actually performed with active species by plasma diffused from this space.

Next, the operation of the present embodiment configured as described above will be described. First, the semiconductor wafer W is housed in the processing container 4 by the transfer arm via the gate valve 40, and the lifter pins (not shown) are moved up and down to place the wafer W on the mounting surface on the upper surface of the mounting table 6. I do.

Then, while maintaining the inside of the processing vessel 4 at a predetermined process pressure, for example, in the range of 0.1 to several tens mTorr, the argon gas is supplied from the plasma gas supply nozzle 20 while controlling the flow rate, and the processing gas supply nozzle is provided. From 22, an etching gas such as CF _{4 is} supplied while controlling the flow rate. At the same time, the microwave from the microwave generator 50 is supplied to the antenna member 44 via the waveguide 52 to form an electric field in the processing space S that exponentially attenuates as the distance from the antenna surface increases. To generate plasma to perform an etching process.

Here, the microwave of, for example, 2.45 GHz generated by the microwave generator 50 propagates in the coaxial waveguide 44 in the TEM mode, reaches the antenna member 44 of the radial waveguide box 46, and During radial propagation from the center of the disk-shaped antenna member 44 to which the cable 52B is connected to the peripheral portion, an electrostatic field is generated between the slits 60 formed concentrically in the antenna member 44, and An electrostatic field is formed in the upper part of the processing space S immediately below the antenna member, specifically, in the plasma forming region S10, such that the static electric field attenuates exponentially as the distance from the antenna surface increases. The argon gas excited by the electrostatic field is turned into plasma, diffuses into the process region S20 located below, and activates the processing gas to form active species, and the surface of the wafer W is processed by the action of the active species. For example, etching is performed.

Here, in the present invention, since the length L of the slit 60 and the distance S1 between the slits adjacent to each other in the radial direction of the antenna member 44 are defined as described above, almost no electromagnetic waves are emitted from the antenna member 44. Instead, only an electric field is formed that decays exponentially with distance from the antenna surface. Therefore, in the case of a structure that emits an electromagnetic wave as in the prior application technology, when the plasma density increases with the application of power, the vibration frequency also increases, the relative dielectric constant becomes substantially zero, and it is not possible to apply power further. As described above, the plasma density generated from the above has a limit, but by applying power using an electrostatic field as in the present invention, such an upper limit is eliminated, and power can be supplied efficiently. And more power can be input.

Therefore, the plasma density can be increased in accordance with the amount of input power, and the antenna member 44
, A high-density plasma can be stably formed over the entire region of the plasma forming region S <b> 10 below. When the present inventors supply power in the form of an electromagnetic wave in the slit shape proposed earlier, the maximum density of the plasma is approximately 7 × 10 ¹⁰ / c.
m ³ , where a cut-off occurred and no more high-density plasma could be formed, but approximately 1 × 1 when power was applied using an electrostatic field as in the present invention.
The plasma density could be increased to 0 ¹² / cm ³ , and good results could be obtained.

In an apparatus having a structure capable of separating the inside of the processing chamber S into a plasma forming region S10 and a process region S20 therebelow, the plasma forming region S10 is formed in the plasma forming region S10 as shown in FIG. The plasma or dissociated gas diffuses into the lower process region S20, where active species of the processing gas are formed. Therefore, as shown in FIG. 5, when the intensity of the electrostatic field in the plasma formation region S10 is formed uniformly in the plane, the generated plasma diffuses and flows downward as described above, so that the plasma density (active species density) in the process region S20 is generated. (Equivalent to the same as above) at the peripheral portion 64 to cause sagging, so that in-plane uniform processing of the wafer may not be performed.

Therefore, as shown in FIG. 3, by gradually increasing the length L of the slit 60 gradually from the center to the peripheral side of the antenna member 44, the length L of the slit immediately below the antenna member is reduced. The strength of the electrostatic field can be greater than at its center. The state at this time is shown in FIG. 6, in which the intensity of the electrostatic field in the plasma forming region S10 is slightly higher at the peripheral portion 66 than at the center portion thereof, and therefore, is located below the peripheral portion 66. The sagging of the shoulder (peripheral portion) of the electrostatic field in the process region S20 is suppressed,
By compensating the sagging, the density becomes uniform over the entire process region, and high-density plasma (active species) can be stably generated.

In the above embodiment, an apparatus having a structure in which the height of the processing space S is large and two regions having different functions vertically can be formed has been described as an example. However, the present invention is not limited to this type of apparatus. Of course, the present invention can be applied to an apparatus in which the distance between the antenna member and the mounting table is narrowed and the plasma forming region and the process region are integrated. Here, specific shapes of the planar antenna member used in the device of the present invention are shown in FIGS.

FIGS. 7 to 10 are plan views showing the planar antenna members of the first to fourth embodiments, respectively. In each of the embodiments, a matching slit 100 is formed at the outermost periphery for almost completely converting the microwave propagated so far into an electrostatic field. Improving efficiency. here,
The microwave frequency uses a high frequency of 2.45 GHz,
Considering the relative permittivity of ceramic material, the guide wavelength is about 40m
m. Table 1 shows the parameters of the antenna members.
Is shown in

[0037]

[Table 1]

Here, Rmax indicates the diameter up to the outermost slit, and Rmin indicates the diameter up to the innermost slit. In Examples 3 and 4, the slit length other than the alignment slit was 29.5 mm.
２３23.2 mm, which indicates a state in which the slit length gradually increases within this range as going outward in the radial direction as described above. It should be noted that each parameter here is merely an example as a matter of course, and is not limited to this.

In the first aspect of the present invention, microwaves are supplied to the center of the disk-shaped antenna member 44 using a coaxial waveguide as a radial structure by arranging slits concentrically or spirally, and supplying the microwave to the center. The structure is such that when microwaves propagate radially outward from the antenna, energy is emitted downward, but this is not a limitation. For example, each slit may be formed in the antenna member so as to be parallel to each other. You may. FIG. 11 is a cross-sectional view showing an antenna member of such a device of the second invention, FIG. 12 is a plan view thereof, and FIG. 13 is a schematic diagram showing a state of introduction of microwaves in a plan view. In the illustrated example, only the vicinity of the antenna member is shown, and the description of other parts is omitted.

As shown in the drawing, in the second embodiment, a microwave is propagated by using a normal rectangular waveguide 70 instead of a coaxial waveguide, and a circle accommodated in a waveguide box 72 is provided. A plurality of copper partition walls 74 of the same material are erected from the surface of the plate-shaped antenna member 44 and are provided at equal intervals, three in the illustrated example. Thereby, the inside of the waveguide box 72 becomes 4
A plurality of, ie, four, branch waveguides 76 whose upper ends communicate with the rectangular waveguide 70 are formed.

In each of the branch waveguides 76 defined by the partition walls 74, a number of slits 60 arranged in parallel with each other are formed in the corresponding antenna member. The length L of each slit and the distance S1 between adjacent slits are formed in exactly the same manner as in the first embodiment. That is, the length L of the slit is shorter than the guide wavelength of the microwave, for example, is set to about 略 of the guide wavelength, and the distance S1 between the slits is also shorter than the guide wavelength of the microwave, for example, the guide wavelength. Is set to approximately 1/2. The distance L5 between the two partition walls 74, 74
Is 1 / の of the guide wavelength λg of the microwave as in the following equation.
The number is set to be 2 or more and is set to be equal to or less than the guide wavelength so that a higher-order mode electrostatic field is not generated. 1 / 2.lambda.g.ltoreq.L5.ltoreq.g In the illustrated example, the partition wall 7 is provided for easy understanding.
Although only three are formed, many are actually formed. Further, the slits formed in each branch waveguide 76 are illustrated in a single row, but may be in a plurality of rows, and may not be parallel to each other or may not be at equal intervals. Further, the slit 60 may not be parallel to the partition wall 74,
It does not necessarily need to be orthogonal.

Then, the inside of the waveguide box 72 is evacuated by hermetically interposing a sealing member 58 made of a ceramic material in the middle of the rectangular waveguide 70 at a point where the ceramic material 62 is filled as a dielectric material. The point that the state is maintained is the same as in the first invention. In addition, the ceramic material 62 as a dielectric also serves as a vacuum shield. In the illustrated example, the antenna member has a disk shape. However, the antenna member may be formed into a rectangular shape such as a square or a rectangle large enough to cover the entire upper part of the processing space. .

In the case of the second invention, the same operation and effect as those of the first invention are exhibited. That is, the microwave propagating through the rectangular waveguide 70 is sequentially introduced into each branch waveguide 76 as shown by the arrow, and
Each time, the input power is input from the slit group into the processing space as an electrostatic field that attenuates exponentially as the distance from the antenna surface increases.

Therefore, unlike the prior art in which the electromagnetic wave is emitted, even if the plasma density is increased by the power input and the relative dielectric constant approaches zero, further power input becomes possible. In each of the above-described embodiments, the plasma etching process of the semiconductor wafer has been described as an example. However, the present invention is not limited to this, and can be applied to any device using plasma, such as a plasma ashing device, The present invention can be applied to a plasma CVD apparatus or the like. Further, the object to be processed is not limited to a semiconductor wafer, and can be applied to processing of another object to be processed, for example, an LCD substrate which is expected to have a large size. . The distribution of the slits of the planar antenna member is not limited to a concentric shape or a spiral shape. What kind of distribution can be obtained as long as an electrostatic field can be formed in the processing space without substantially oscillating electromagnetic waves. But ok
Preferably, it can be arbitrarily selected according to the shape of the object to be processed. For example, when a rectangular LCD substrate is used as the object to be processed, the slits can be arranged along a number of rectangular lines having a common center.

[0045]

As described above, according to the plasma processing apparatus of the present invention, the following excellent operational effects can be exhibited. Microwaves flow through the planar antenna member to form an electric field in the processing space that exponentially decays away from the antenna surface to generate plasma, so power is applied regardless of the plasma density. Therefore, a plasma having a much higher density can be formed uniformly and stably over a wide range as compared with the case where electric power is supplied by utilizing electromagnetic waves. In particular, in the case of a radial structure in which the slit is formed in a concentric or spiral shape, the length of the slit is set to be slightly longer as it is positioned radially outward of the antenna member, so that the peripheral portion of the antenna member is The electromagnetic field can be strengthened, and therefore, a decrease in the plasma density at the periphery of the process region corresponding to the periphery can be compensated, and the in-plane uniformity of the plasma density can be further improved. Also, the outermost circumference is longer than the inner slit.
Provide a slit and substantially reduce the length of this inner slit
By setting the same, the outer circumference of the antenna member
The antenna efficiency can be improved by eliminating reflected waves.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of a plasma processing apparatus according to a first invention.

FIG. 2 is a plan view showing an antenna member used in the processing apparatus shown in FIG.

FIG. 3 is an enlarged plan view of the antenna member shown in FIG.

FIG. 4 is a diagram schematically showing a plasma formation region and a process region in a processing space.

FIG. 5 is a diagram illustrating a plasma density in a process region when the electrostatic field intensity in the plasma formation region is uniform.

FIG. 6 is a diagram showing a plasma density in a process region when the intensity of an electrostatic field at a peripheral portion of a plasma formation region is increased.

FIG. 7 is a plan view illustrating a planar antenna member according to the first embodiment.

FIG. 8 is a plan view illustrating a planar antenna member according to a second embodiment.

FIG. 9 is a plan view illustrating a planar antenna member according to a third embodiment.

FIG. 10 is a plan view illustrating a planar antenna member according to a fourth embodiment.

FIG. 11 is a sectional view showing an antenna member of the plasma processing apparatus of the second invention.

FIG. 12 is a plan view of the antenna member shown in FIG. 11;

FIG. 13 is a schematic diagram illustrating a state of introduction of microwaves in a plan view.

[Explanation of symbols]

 Reference Signs List 2 plasma etching apparatus (plasma processing apparatus) 4 processing container 6 mounting table 44 antenna member 50 microwave generator 52 waveguide 60 slit 70 rectangular waveguide 72 waveguide box 74 partition wall 76 branch waveguide 100 matching slit L Slit length S Processing space S1 Distance between adjacent slits S10 Plasma formation area S20 Process area W Workpiece (semiconductor wafer)

──────────────────────────────────────────────────続 き Continuing from the front page (73) Patent holder 591076763 Junichi Takada 1-1-24- 204 Sagamihara, Sagamihara-shi, Kanagawa (73) Patent holder 594169385 Yasuhiro Horiike 3-2-1 Higashifushimi, Nishi-Tokyo, Tokyo ( 72) Inventor Nobuo Ishii 5-36 Akasaka, Minato-ku, Tokyo Inside Tokyo Electron Co., Ltd. (72) Inventor Naohisa Goto 6-15-1-1-A, Dobashi, Miyamae-ku, Kawasaki City, Kanagawa Prefecture A514 (72) Inventor Ando Shin 1-1, I-312, Ogura, Sachi-ku, Kawasaki City, Kanagawa Prefecture (72) Inventor Junichi Takada 5-36-8-102, Niwahigashi, Funabashi City, Chiba Prefecture (72) Inventor Yasuhiro Horiike 3-chome Higashifushimi, Hoya City, Tokyo JP-A-3-1911073 (JP, A) JP-A-5-129095 (JP, A) JP-A-3-20460 (JP, A) JP-A-1-283359 (JP) , A) -117437 (JP, U) (58 ) investigated the field (Int.Cl. ^7, DB name) H01L 21/3065 C23C 16/507 H01L 21/205

Claims (10)

(57) [Claims] An airtight processing container having a mounting table for mounting an object to be processed therein, a microwave generator, and a microwave generator for guiding microwaves generated by the microwave generator to the processing container. A waveguide, a planar antenna member connected to the waveguide and arranged opposite to the mounting table, a large number of slits formed in a large number of loops in the antenna member, and into the processing container. Means for supplying gas, and the length of the slit is set shorter than the guide wavelength of the microwave in order to form an electrostatic field that attenuates exponentially with distance from the antenna surface in the processing container. And the distance between the slits in the radial direction of the antenna member is set to a length shorter than the guide wavelength of the microwave , and the length of the slit is set to the length of the antenna unit.
From the center of the material to the radially outer side
Next, set slightly larger, the periphery of the antenna member
The plasma density at the center to be greater than at the center
The plasma processing apparatus characterized by being configured to. 2. An airtight processing container having a mounting table for mounting an object to be processed therein, a microwave generator, and a microwave generator for guiding microwaves generated by the microwave generator to the processing container. A waveguide, a planar antenna member connected to the waveguide and arranged opposite to the mounting table, a large number of slits formed in a large number of loops in the antenna member, and into the processing container. Means for supplying gas, and the length of the slit is set shorter than the guide wavelength of the microwave in order to form an electrostatic field that attenuates exponentially with distance from the antenna surface in the processing container. At the same time, the distance between the slits in the radial direction of the antenna member is set to a length shorter than the guide wavelength of the microwave , and the outermost periphery of the planar antenna member is
Microwaves propagated here are almost completely converted into electrostatic fields
To be set longer than the length of the inner slit
Alignment slit is formed,
The lengths of the inner slits located on the sides are all substantially the same
A plasma processing apparatus characterized by being performed . Wherein the loop is a plasma apparatus according to claim 1 or 2, characterized in that a concentric or spiral. 4. The method according to claim 1, wherein the phases of the electric fields formed by the slits adjacent in the radial direction of the antenna member are set to be opposite to each other .
The plasma processing apparatus according to any one of the above. 5. The longitudinal direction of the slit, the plasma processing apparatus according to any one of claims 1 to 4, characterized in that along a substantially tangential direction of the concentric circle or spiral of the slit. 6. An airtight processing container provided with a mounting table for mounting an object to be processed therein, a microwave generator, and a microwave generator for guiding microwaves generated by the microwave generator to the processing container. A waveguide, a plurality of branch waveguides connected to the waveguide, a planar antenna member connected to the branch waveguide and arranged opposite to the mounting table, and A multiplicity of slits formed so as to be parallel to each other in each branch waveguide, and means for supplying gas into the processing container, wherein the length of the slit is set to an antenna surface in the processing container. In order to form an electrostatic field that attenuates exponentially with distance from the microwave, the distance between the slits in a direction orthogonal to the longitudinal direction of the slits is set shorter than the guide wavelength of the microwaves, and wave The length is set to be shorter than the length , and the outermost periphery of the planar antenna member is
Converts the transmitted microwave almost completely into an electrostatic field
Is set longer than the length of the inner slit.
A mating slit is formed, inside the matching slit
The lengths of the inner slits located are all substantially the same.
The plasma processing apparatus characterized by being. 7. Each of the slits has a wavelength of ± 30% of a guide wavelength around a half of a guide wavelength of the microwave.
7. The plasma processing apparatus according to claim 1, having a length in the range of%. 8. A distance between slits adjacent in the width direction of the slit is 5% to 50% of a guide wavelength of the microwave.
8. The plasma processing apparatus according to claim 1, wherein the length is set within a range of%. 9. A dielectric which covers the surface of the planar antenna member opposite to the surface facing the object to be processed and shortens the wavelength of the microwave supplied from the waveguide to a guide wavelength. The plasma processing apparatus according to claim 1, further comprising: 10. The branch waveguide has a plurality of partition walls erected by an antenna member and extending in parallel with each other, and each branch waveguide is defined between adjacent partition walls, and 7. The plasma processing apparatus according to claim 6, wherein the plasma processing apparatuses are arranged along the partition wall so as to be adjacent in the width direction.