JP2004235434A - Plasma processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a plasma system having a slot plate for preventing variation of the characteristics of the microwave while reducing the thermal deformation strain by heat. <P>SOLUTION: The plasma processing system comprises a microwave generator 1, a circular slot plate 8 provided between the microwave generator 1 and a reactor 4b while having a plurality of slots in order to make the field strength distribution of the microwave substantially uniform along the processing surface of a sample 12, a first circular sealing dielectric 9 provided between the slot plate 8 and the reactor 4b in order to maintain or enhance the uniformity in the field strength distribution of microwave, and a means for processing the sample 12 using the plasma generated in the reactor 4b by the microwave. The slot plate 8 is made 1 mm thick or thicker. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a plasma processing apparatus that uses plasma generated by microwaves.
[0002]
[Prior art]
A plasma processing apparatus using a microwave (for example, 2.45 GHz) is used for forming an IC (integrated circuit). In this plasma processing apparatus using microwaves, high-density, low-electron-temperature plasma can be obtained by microwaves having a high frequency. Therefore, it is possible to suppress the influence of electrical or physical damage to a thin film such as a gate oxide film.
Furthermore, in recent years, the miniaturization of ICs and the increase in diameter of wafers have progressed, and accordingly, it has been required to uniformly form a large-diameter thin film. Therefore, such a plasma apparatus uses a slot plate for uniformly introducing microwaves into a dielectric. By using the slot plate, the microwave is made uniform, and the plasma generated by the microwave is made uniform. The uniformized plasma uniformly separates and excites the gas to form a uniform thin film. For the slot plate, a thin metal plate is used to prevent protrusions that occur when forming a rectangular slot that serves as a microwave introduction window, and to prevent disturbance of the microwave electrolytic intensity distribution due to the thickness of the slot plate. Have been. When this thin metal plate is used, if the degree of coupling of the microwaves introduced from the thin metal plate is too large, problems such as sparks and abnormal discharge occur. Therefore, the length of the slot plate in the long side direction (hereinafter, slot length) is set to be sufficiently shorter than half of the microwave wavelength at the upper part of the slot plate.
[0003]
Also, when microwaves are introduced into the dielectric from the slot of the antenna, to increase the electric field strength of the microwaves introduced into the dielectric from a slot whose slot length is sufficiently shorter than half the wavelength of the microwave propagating in the antenna. A technique for reducing the thickness of an antenna is disclosed (for example, see Patent Document 1).
[0004]
[Patent Document 1]
JP-A-2002-50615
[Problems to be solved by the invention]
However, since thin slot plates and antennas made of metal are used, the heat generated during plasma generation is difficult to dissipate, the temperature inside the plasma device rises, and the slot plates are deformed due to heat and distortion occurs. appear. Therefore, there is a problem that the characteristics change such as a change in microwave transmittance and a decrease in microwave uniformity due to the slot.
Thus, the present invention provides a plasma apparatus having a slot plate that prevents fluctuations in microwave characteristics while reducing thermal deformation distortion due to heat.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a first invention of the present application is a plasma processing apparatus for performing plasma processing on a sample in a reactor, comprising: a microwave generation unit configured to generate a microwave; A slot plate provided between the sample and a plurality of slots, the slot plate for making the electric field intensity distribution of the microwave generated from the microwave generation means substantially uniform along the processing surface of the sample, and the slot A first dielectric member provided between the plate and the reactor, for maintaining or further improving the uniformity of the electric field intensity distribution of the microwave supplied from the slot plate, and generated in the reactor by the microwave; Processing means for processing the sample using plasma, wherein the thickness of the slot plate is 1 mm or more.
[0007]
When the thickness of the slot plate is 1 mm or more, the heat radiation characteristics and rigidity of heat generated when plasma is generated are improved, and microwaves introduced from the slot are reduced, thereby causing sparks and abnormal discharge. The problem can be reduced, and the microwave can be easily kept substantially uniform along the processed surface of the sample (hereinafter, a microwave having a substantially uniform electric field intensity distribution is referred to as a uniform microwave. "" Means "substantially uniform in the direction along the processing surface of the sample").
The second invention of the present application provides the plasma processing apparatus according to the first invention, wherein a second dielectric is further provided between the microwave generating means and the slot plate.
[0008]
Since the non-uniformity of the microwave is reduced by the second dielectric, the slot plate, and the first dielectric, it is easy to uniform the microwave.
A third invention of the present application provides the plasma processing apparatus according to the first or second invention, wherein the thickness of the slot plate is 3 mm or more.
The heat dissipation characteristics and rigidity can be further improved by the slot plate having a thickness of 3 mm or more.
Fourth aspect of the present invention, in the first or second invention, wherein the slots of the slot plate has a rectangular shape, the length L ₁ in the long side direction of the slots, satisfies the following expression (1) substantially A plasma processing apparatus is provided.
[0009]
L ₁ ≧ (3/8) λ _A (1)
Here, λ _A is the wavelength of the microwave introduced into the slot plate.
With the above configuration, even when the thickness of the slot plate is large, it is easy to prevent the microwave from being attenuated by the slot, and the degree of coupling between the microwave passing through the slot plate and the microwave in the first dielectric can be improved. .
The present fifth invention, in the fourth invention, the length L ₁ in the long side direction of the slot, to provide a plasma processing apparatus which satisfies the following formula (2) substantially.
L ₁ ≧ (1/2) λ _A (2)
Here, λ _A is the wavelength of the microwave introduced into the slot plate.
[0010]
With the above configuration, even when the thickness of the slot plate is large, the attenuation of the microwave by the slot can be further prevented, and the transmission characteristics of the microwave can be improved. Therefore, it is possible to improve the degree of coupling between the microwave passing through the slot plate and the microwave in the first dielectric.
The present sixth invention, in the fifth invention, the length L ₁ in the long side direction of the slot is substantially to provide a plasma processing apparatus is _{L 1 = (1/2) λ A} . Here, λ _A is the wavelength of the microwave introduced into the slot plate.
[0011]
According to the above configuration, the length in the long side direction of the slot becomes substantially the resonance length of the wavelength of the microwave introduced into the slot plate. Therefore, even when the length of the slot in the short side direction is small, a high degree of coupling can be obtained without increasing the microwave transmittance and disturbing the microwave distribution. Further, substantially the center distance L ₂ of the slots adjacent in the longitudinal direction of the slot, when L 2 ₌ lambda _A, more preferably since the microwave phase are aligned to be introduced into the first dielectric from the slot.
A seventh invention of the present application provides the plasma processing apparatus according to the second invention, wherein a cross section of the first dielectric and the second dielectric along a processing surface of the sample is rectangular.
[0012]
By making the cross section of the first dielectric material and the second dielectric material along the processing surface of the sample rectangular, the distribution of the microwave electric field intensity becomes uniform as a whole along the processing surface of the sample. Plasma is generated uniformly by the uniform microwave, and a uniform thin film can be formed by gas molecules excited and activated by the plasma. In addition, even if the process conditions such as the flow rate and the composition ratio of the gas are changed or the process conditions are changed due to maintenance or the like, the microwave electric field intensity distribution is not easily biased because the region where the microwave propagates is rectangular. Therefore, the process margin can be expanded.
[0013]
The present eighth invention, in the seventh invention, the slot is approximately the same shape of the same size, generally provided along the same direction, the distance L ₅ between the centers of adjacent said slot is substantially , L ₅ = n _L5 λ ₂ . Here, λ ₂ : wavelength of the microwave in the second dielectric, n _L5 : an integer of 1 or more.
The microwave of the wavelength λ _{2 in} the second dielectric material has a distance between the centers equal to an integral multiple of λ ₂ and has a rectangular shape of the same size and is provided from the slot provided along the same direction to the first dielectric material. When the microwaves are introduced, the phases of the microwaves in the first dielectric at the center positions of the respective slots are aligned, so that the degree of coupling between the microwaves introduced into the first dielectric and the microwaves propagating in the first dielectric is increased. Can be increased.
[0014]
In a ninth aspect of the present invention, in the seventh aspect, the slots have substantially the same size and the same shape, are arranged in line symmetry with respect to any of axes perpendicular to each other along the slot plate, and are arranged between the centers of adjacent slots. distance _{L 6} of _{substantially,} to provide a plasma processing apparatus is _{L 6 = n L6 (λ 2} /2). Here, λ ₂ : wavelength of the microwave in the second dielectric, n _L6 : an integer of 1 or more.
As in the eighth aspect, the degree of coupling between the microwave introduced into the first dielectric and the microwave propagating through the first dielectric can be increased, and the mounting density of the slots can be further increased.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
<Plasma processing equipment>
The plasma processing apparatus has a microwave generator, a processing chamber, and a microwave propagation region above the processing chamber, and performs processing as described below.
Microwaves generated by the microwave generator propagate in the microwave propagation region, and an electric field is formed in the processing chamber in a gas atmosphere. Plasma is generated by the electric field and the gas, and processing such as film formation, etching, and gas-phase cleaning is performed on a sample in the processing chamber by the chemical species generated by the plasma.
[0016]
Examples of such a plasma processing apparatus using plasma include an apparatus that performs oxidation and nitridation using plasma (hereinafter, referred to as a plasma oxynitriding apparatus), a plasma CVD (Chemical Vapor Deposition) apparatus, a plasma etching apparatus, a plasma ashing apparatus, and a plasma cleaning apparatus. Equipment, plasma annealing equipment and the like.
Hereinafter, a plasma oxynitriding apparatus will be described as an example of the plasma processing apparatus of the present invention.
<First Embodiment>
[Constitution]
1 is an external view of a plasma oxynitriding apparatus according to a first embodiment, FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 in a direction perpendicular to a processing surface of a sample including AA ′ in FIG. 1, and FIG. FIG. 4 is an exploded perspective view of a main part of the plasma oxynitriding apparatus shown in FIG.
[0017]
The plasma oxynitriding apparatus according to the first embodiment includes a microwave generator 1, a waveguide 2, and a chamber 4. The chamber 4 is provided with a gas inlet 5 for introducing a gas such as a film forming gas and a gas outlet 6 for discharging the gas. The chamber 4 has a cylindrical chamber lid (hereinafter, circular chamber lid) 4a and a cylindrical processing chamber (hereinafter, circular processing chamber) 4b. The circular processing chamber 4b is provided with a sample stage 11 on which the sample 12 is placed at a position facing the circular chamber lid 4a. On the side surface of the circular processing chamber 4b, a gas introduction unit 10 for supplying a gas such as a film forming gas from the gas inlet 5 to the circular processing chamber 4b is provided. On the other hand, on the circular chamber lid 4a, a resonator 7, a cylindrical slot plate (circular slot plate) 8, and a cylindrical sealing dielectric (hereinafter referred to as a circular sealing dielectric) 9 are sequentially placed on the circular processing chamber 4b. It is provided so as to cover the upper part of. As shown in FIG. 4A, rectangular slots 8a are radially provided in the circular slot plate 8. FIGS. 4 (a) to the length W ₁ of the short side direction of the slot 8a shown is sufficiently shorter than the length L ₁ in the long side direction. As the circular slot plate 8, a radial line slot antenna shown in FIG. 4B may be used. In this case, the sum of the length _{L a2} of the long side direction of FIG. 4 the length of the long side direction of the slot 8a1 of (b) _{L a1} and slot 8a2 _includes those represented by _{L 1} = L a1 ₊ L _a2 I do. A coaxial antenna 3 provided in the waveguide 2 is provided on the chamber 4.
[0018]
Here, the thickness t of the circular slot plate 8 is preferably 1 mm or more from the viewpoint of rigidity and heat radiation characteristics. When the thickness of the circular slot plate 8 is 1 mm or more, the heat radiation characteristics and rigidity generated when generating plasma or the like are improved, and the microwaves introduced from the slots 8a are reduced. Problems such as generation can be reduced, and microwave uniformity can be easily maintained. It is preferable that the thickness t is 3 mm or more, because the above problem can be further reduced.
The slot length _{L 1} in the long side direction of the slot 8a is preferably _{L 1 ≧ (3/8) λ 7} , more preferably set to be _{L 1 ≧ (1/2) λ 7} . Here, λ ₇ is the wavelength of the microwave in the resonator 7. By thus setting the slot length L _1, easily preventing the attenuation of the microwave by the slots 8a, even if the thickness t of the slot plate is thick, microwaves and round in the resonator 7 having passed through the circular slot plate 8 The degree of coupling with microwaves in the sealing dielectric 9 can be improved. More preferably, it is set so that L ₁ = (１ ／) λ ₇ . By doing so, the slot length L ₁ becomes substantially the resonance length of the wavelength λ ₇ , and even in the case of the circular slot plate 8 having the thickness t of 1 mm or more, the length W _{1 of the} slot 8 a in the short side direction is small. Even in this case, a sufficient transmittance of microwaves to the circular sealing dielectric 9 can be obtained, and attenuation of microwaves by the circular slot plate 8 can be prevented. In addition, a high degree of coupling between the microwave introduced into the circular sealing dielectric 9 from the resonator 7 via the circular slot plate 8 and the microwave in the circular sealing dielectric 9 without disturbing the distribution of the microwave. Can be obtained. Therefore, a higher degree of coupling can be obtained while reducing generation of non-uniform microwaves due to deformation of the slot plate, abnormal discharge, microwave attenuation, and the like. Therefore, a uniform thin film can be uniformly generated on a large-diameter wafer by efficiently generating uniform plasma. (Hereinafter, a microwave having a substantially uniform electric field intensity distribution is referred to as a uniform microwave. In the following, "uniform" means "substantially uniform in a direction along the processing surface of the sample 12.")
Further, substantially the center distance L ₂ of the slots adjacent in the long side direction shown in FIG. 4, when L 2 ₌ lambda _7, phases of microwaves introduced into a circular sealing dielectric 9 each slot 8a is It is more preferable because they are aligned. Furthermore, it is preferable that the relative permittivity inside the slot 8a and the relative permittivity inside the circular sealing dielectric 9 be substantially the same, because the reflection of microwaves when passing through the slot 8a can be reduced.
[0019]
Since the relationship between the thickness t of the circular slot plate 8 and the thermal deformation strain is in a reciprocal relationship to the relationship between the thickness t and the transmittance, it is necessary to determine the relationship with the characteristics of the plasma oxynitriding apparatus.
Further, when a cylindrical antenna dielectric (hereinafter, “circular antenna dielectric”) 15 is provided on the upper part of the circular slot plate 8, the circular antenna dielectric 15, the circular slot plate 8 and the circular sealing dielectric 9 form a circular sealing dielectric. The distribution of the microwave electric field intensity in the body 9 is further uniformed. Further, other antennas such as a slot antenna and a rectangular waveguide may be provided instead of the coaxial antenna 3. Further, as the above-mentioned dielectric, a substance having a small dielectric loss such as quartz, fluororesin, polyethylene, and polystyrene is preferable. The dielectric includes a case where the relative dielectric constants of vacuum, air, and gas are “1”. Also, a case where at least a part of the surface of the dielectric is covered with a conductor is included. Further, as a material of the slot plate, a metal plate such as Cu or Al is used.
[processing]
In this plasma oxynitriding apparatus, for example, a film forming process is performed as follows.
[0020]
First, the inside of the circular processing chamber 4b is evacuated from the gas discharge port 6 to a predetermined degree of vacuum, and gas is introduced into the circular processing chamber 4b through the gas inlet 5 and the gas inlet 10. Next, the microwave generated by the microwave generator 1 is introduced into the circular sealing dielectric 9 via the circular slot plate 8 to make the electric field intensity distribution uniform. The microwave is introduced into the circular processing chamber 4b. The plasma generated by the introduced microwaves excites and activates gas molecules to generate chemical species, and forms a thin film on the surface of the sample 12.
[Experimental result]
Next shows the relationship between the distortion due to transmission and thermal deformation of the slot length L ₁ of the thickness t and slot 8a of the circular slot plate 8. FIG. 5 is an explanatory diagram showing the relationship between the thickness t of the circular slot plate 8 and the strain due to thermal deformation. FIG. 6 shows the relationship between the transmittance t and the thickness t of each of the circular slot plates 8 having slots of the slot lengths L ₁ = (）) λ ₇ , (３) λ ₇ , and (１ ／) λ _7. FIG.
[0021]
5 and 6 are experimental results when the wavelength lambda ₇ in the cavity 7 is filled with a dimension enough to be free-space wavelength, and quartz.
According to FIG. 5, when the thickness t of the circular slot plate 8 is 1 mm or more, the thermal deformation strain of the circular slot plate 8 is about 40 μm or more. Therefore, when the thickness t is 1 mm or more, the rigidity can be improved and good heat radiation characteristics can be obtained, so that the thermal deformation strain is sufficiently reduced to 1/10 or less of the thickness t of the circular slot plate 8, The effect on microwaves due to deformation can be reduced. Further, when the thickness t is in the range of 1 ≦ t ≦ 3 (mm), the thermal deformation strain is about 20 μm as shown in FIG. Further, the heat radiation characteristic of heat generated when generating plasma is further improved, and problems such as sparks and abnormal discharge can be further reduced.
[0022]
Transmittance thickness t of each slot length L ₁ of 1mm than 6, all have about 80% or more, no problem in both rigidity and permeability. In particular, it is preferable that L ₁ ≧ (3/8) λ ₇ because the transmittance becomes about 90% or more and the transmittance of microwaves can be improved. When the thickness t is in the range of 1 ≦ t ≦ 3 (mm), the transmittance becomes about 70% or more when L ₁ ≧ (3/8) λ _7, and when L ₁ ≦ (1/4) λ ₇ , The microwave transmittance can be sufficiently increased. Similarly, when the thickness t is 3 mm or more, the thermal deformation strain is as small as about 20 μm or less, and when L ₁ ≧ (3/8) λ ₇ , a decrease in transmittance can be suppressed. For example, when the thickness t is 5 mm, the thermal deformation strain is about 5 μm, and the transmittance is about 55% or more.
<First embodiment>
The plasma oxynitriding apparatus according to the first embodiment will be described more specifically with reference to FIGS. 7 is an external view of the plasma oxynitriding apparatus according to the first embodiment, FIG. 8 is a cross-sectional view of the apparatus of FIG. 7 perpendicular to the X-axis in FIG. 7 including BB ', and FIG. FIG. 10 is an exploded perspective view of a main part of the oxynitriding apparatus, FIG. 10 is a perspective view of a rectangular slot plate 36 having a plurality of slots 36a, and FIG.
[overall structure]
The plasma oxynitriding apparatus according to the present embodiment includes a rectangular waveguide 20, an H-plane slot antenna 30, and a chamber 25 (hereinafter, rectangular chamber) having a rectangular cross section along the processing surface of the sample 12. The rectangular chamber 25 has a rectangular processing chamber (hereinafter, rectangular processing chamber) 25b having a rectangular cross section along the processing surface of the sample 12 and a rectangular processing chamber 25b, and has a rectangular cross section along the processing surface of the sample 12. A chamber lid (hereinafter, rectangular chamber lid) 25a is provided.
[0023]
As shown in FIG. 9, the rectangular chamber lid 25a has an antenna dielectric (hereinafter, rectangular antenna dielectric) 34 having a rectangular cross section along the processing surface of the sample 12, and a cross section along the processing surface of the sample 12, in order from the top. Has a rectangular slot plate (hereinafter, rectangular slot plate) 36 and a sealing dielectric (hereinafter, rectangular sealing dielectric) 38 having a rectangular cross section along the processing surface of the sample 12.
The rectangular slot plate 36 is provided with a rectangular slot 36a. The length L ₃ of the slot 36a in the long side direction is L ₃ = (１ ／) λ ₃₄ , and the length W ₂ of the short side direction is sufficiently shorter than the length L ₃ in the long side direction. The thickness t of the rectangular slot plate is 1 mm. Preferred addition, the slot 36a, as shown in FIG. 11, so that the center distance L ₄ of the adjacent slots 36a slot is substantially L _{4 =} λ _34, and when provided along one direction . Here, lambda ₃₄ is the wavelength of the microwave in the rectangular antenna dielectric 34. The inclination angle of the slot 36a can be changed according to the microwave distribution in the rectangular sealing dielectric 38. In other words, considering the ratio of the propagation component of the microwave in the X direction and the propagation component in the Y direction in the rectangular sealing dielectric 38 in accordance with the processing method of the sample 12 and the processing conditions of the apparatus, the inclination of the slot 36a is considered. Change the angle. An H-plane slot antenna 30 is mounted on the rectangular antenna dielectric 34, and microwaves are introduced from the rectangular waveguide 20 into the rectangular antenna dielectric 34 by the H-plane slot antenna 30.
[0024]
The H-plane slot antenna 30 has an upper portion 30a, a side portion 30b, and a bottom portion 30c. On the bottom portion 30c, that is, on the H-plane of the H-plane slot antenna 30, a rectangular slot 30d is formed along the side direction of the H-plane slot antenna 30, as shown in FIG. The rectangular waveguide 20 is mounted above the H-plane slot antenna 30. Except for the other configuration described below, the configuration is the same as that of the first embodiment.
Hereinafter, each part of the plasma oxynitriding apparatus according to the present embodiment will be described in detail.
[Rectangular antenna dielectric]
The rectangular antenna dielectric 34 formed in a rectangular shape makes the microwave electric field intensity distribution uniform. The rectangular antenna dielectric 34 is separated from the microwave in the rectangular antenna dielectric 34 and the microwave reflected by the plasma in the rectangular processing chamber 25b by the rectangular slot plate 36 provided between the rectangular processing chamber 25b. Is suppressed. Therefore, the microwave propagating in the rectangular antenna dielectric 34 is hardly affected by the plasma, and the electric field intensity distribution of the microwave is easily uniformized.
[Rectangular sealing dielectric]
The rectangular sealing dielectric 38 is formed in a rectangular shape, and maintains or further enhances the uniformity of the electric field intensity distribution of the microwave introduced from the rectangular slot plate 36, and reduces the rectangular shape below the rectangular sealing dielectric 38. An electric field for generating plasma is formed in the processing chamber 25b. In addition, the rectangular sealing dielectric 38 isolates the vacuum processing chamber 25b from the atmosphere and keeps it in a clean space.
[Rectangular slot plate]
The rectangular slot plate 36 maintains or further enhances the uniformity of the electric field intensity distribution of the microwave introduced from the rectangular antenna dielectric 34 while keeping the slot 36a. The rectangular slot plate 36 does not necessarily need to have a rectangular cross section along the processing surface of the sample 12, and may have a shape that covers the rectangular antenna dielectric 34, the rectangular sealing dielectric 38, and the rectangular processing chamber 25b. It may be circular.
[0025]
If the relative permittivity inside the slot 36a and the relative permittivity of the rectangular antenna dielectric 34 are substantially the same, the reflection of microwaves when passing through the slot 36a can be reduced, and the design becomes easy. It is more preferable.
[Rectangular processing room]
In the rectangular processing chamber 25b, an electric field is formed by microwaves in the rectangular sealing dielectric 38. Since a uniform microwave is introduced from the rectangular sealing dielectric 38, a uniform plasma is generated in the rectangular processing chamber 25b. A uniform thin film is formed on the sample 12 by the gas molecules excited and activated by the plasma. The rectangular processing chamber 25b is not a region where microwaves normally propagate because microwaves are reflected and absorbed by plasma generated therein. Therefore, the cross section of the rectangular processing chamber 25b in the direction along the sample 12 processing surface does not necessarily have to be rectangular. However, since the microwave may propagate in the rectangular processing chamber 25b without being completely absorbed, the microwave may travel along the sample 12 processing surface of the rectangular processing chamber 25b so that the uniformity of the plasma is not disturbed by the non-uniform microwave. Preferably, the cross section is rectangular. By doing so, the uniformity of the plasma can be further improved, and a more uniform thin film can be formed.
[H-plane slot antenna]
As shown in FIG. 10, the H-plane slot antenna 30 has rectangular slots 30d at regular intervals along the side direction of the H-plane slot antenna 30 on the bottom 30c. Therefore, the rectangular antenna dielectric 34, the rectangular slot plate 36, and the rectangular sealing dielectric 38 are effective in making the microwave uniform and increasing the uniformity of the microwave electric field intensity distribution. Here, the H-plane slot antenna is used as the antenna, but an E-plane slot antenna, a circular waveguide, a coaxial waveguide, a coupling element other than the slot, or the like can also be used. In particular, when a slot antenna having a rectangular cross section is used, large power does not concentrate at one point, and characteristic fluctuations such as heat generation and abnormal discharge hardly occur. In addition, since the slot antenna has a rectangular shape, it is easy to fix the antenna to the rectangular antenna dielectric 34 and characteristic fluctuations are unlikely to occur, so that uniform plasma can be generated.
[0026]
The H-plane slot antenna 30 may be installed in at least one place, but a plurality of H-plane slot antennas may be provided or branched to introduce microwaves into the dielectric, corresponding to a large apparatus for processing a large-diameter sample. May be. At this time, it is preferable to provide an even number, because the design is easy. It is more preferable to provide 2 ⁿ (n is a natural number).
[Rectangular chamber]
The rectangular chamber 25 is preferably formed in a rectangular cross section along the processing surface of the sample 12 in accordance with the rectangular antenna dielectric 34, the rectangular sealing dielectric 38, and the like, because electrical and structural mismatches are reduced.
[0027]
Therefore, by making the rectangular antenna dielectric 34 and the rectangular sealing dielectric 38 of the plasma oxynitriding device rectangular in cross section along the processing surface of the sample 12, the microwave electric field intensity distribution is along the processing surface of the sample. It becomes uniform as a whole. Plasma is generated uniformly by the uniform microwave, and a uniform thin film can be formed by gas molecules excited and activated by the plasma. In addition, even if the process conditions such as the flow rate and the composition ratio of the gas are changed or the process conditions are changed due to maintenance or the like, the microwave electric field intensity distribution is not easily biased because the region where the microwave propagates is rectangular. Therefore, the process margin can be expanded.
[0028]
In addition, the rectangular antenna dielectric 34, the rectangular slot plate 36, and the rectangular sealing dielectric 38 further uniform the electric field intensity distribution of the microwave in the rectangular sealing dielectric 38, thereby reducing the non-uniformity of the microwave. It can be reduced and microwaves can be easily made uniform.
In the rectangular antenna dielectric 34 and the rectangular sealing dielectric 38, since the uniformed microwave can be attenuated by the plasma, it is not always necessary to satisfy the standing wave condition, and a substantially uniform electric field intensity distribution can be obtained. Any microwave may be used. However, it is preferable that the standing wave condition be satisfied, since the cancellation by multiple reflections is reduced, plasma is more easily generated, and a thin film is more uniformly formed on the surface of the sample 12. For the same reason, it is preferable that the rectangular processing chamber 25b, the rectangular slot plate 36, the H-plane slot antenna 30, and the rectangular waveguide 20 also satisfy the standing wave condition of the microwave.
<Second embodiment>
Hereinafter, the plasma oxynitriding apparatus according to the first embodiment will be described with reference to a second embodiment. However, the plasma oxynitriding apparatus according to the second embodiment has the same configuration as that of the first embodiment except for the slot shape of the rectangular slot plate 36 described below.
[0029]
FIGS. 12 (a) and 12 (b) show the slot shapes of the rectangular slot plate, and FIGS. 13 (a) and 13 (b) show the slot shapes shown in FIGS. FIG. 4 is an explanatory diagram showing a relationship between a microwave and a wavelength at a certain time in a Y direction.
In FIG. 12A, a plurality of rectangular slots 36a are provided in substantially the same size and the same direction. Further, the distance _{L 5} between the centers of adjacent slots 36a, _{substantially} set to satisfy L 5 _{= n L5} λ _34. Here, λ ₃₄ is the wavelength of the microwave in the rectangular antenna dielectric 34, and n _L5 is an integer of 1 or more. The inclination angle of the slot 36a can be changed according to the microwave distribution in the rectangular sealing dielectric 38. In other words, considering the ratio of the propagation component of the microwave in the X direction and the propagation component in the Y direction in the rectangular sealing dielectric 38 in accordance with the processing method of the sample 12 and the processing conditions of the apparatus, the inclination of the slot 36a is considered. Change the angle.
[0030]
When a microwave of wavelength λ ₃₄ propagating in the rectangular antenna dielectric 34 shown in FIG. 13A is introduced into the slot plate 36, the microwave in the hatched portion of FIG. Introduced into the sealing dielectric 38. Therefore, since the phases of the microwaves in the rectangular sealing dielectric 38 at the center position of each slot 36a are aligned, the microwaves introduced into the rectangular sealing dielectric 38 and propagate in the rectangular sealing dielectric 38. The degree of coupling with microwaves can be increased.
On the other hand, in FIG. 12 (b), a plurality of rectangular slots 36a having substantially the same size are provided, and are symmetrical with respect to any one of axes perpendicular to each other along the slot plate. Further, the distance _{L 6} between the centers of adjacent slots 36a, _{substantially,} is set to satisfy the _{L 6 = n L6 (λ 34} /2). Here, λ ₃₄ is the wavelength of the microwave in the rectangular antenna dielectric 34, and n _L6 is an integer of 1 or more. The inclination angle of the slot 36a is as described above.
[0031]
When a microwave having a wavelength λ ₃₄ propagating in the rectangular antenna dielectric 34 shown in FIG. 13B is introduced into the slot plate 36, the microwave in the hatched portion in FIG. Introduced into the sealing dielectric 38. Therefore, as described above, it is possible to increase the mounting density of the slots while suppressing the loss due to the interference between the microwaves, and to more uniformly excite the plasma.
[Other Embodiment Examples]
(A) The present invention is applicable to compounds other than the silicon process, FPD (Flat Panel Display) processes, and the like. Further, the present invention can be applied to a microwave irradiation device or a microwave heating device that does not use plasma.
(B) The above embodiments can be used in combination as needed.
[0032]
【The invention's effect】
According to the present invention, it is possible to provide a plasma device having a slot plate that prevents a change in the characteristics of microwaves while reducing thermal deformation distortion due to heat.
[Brief description of the drawings]
FIG. 1 is an external view of a plasma oxynitriding apparatus according to a first embodiment.
FIG. 2 is a cross-sectional view of the apparatus of FIG. 1 in a direction perpendicular to a processing surface of a sample including AA ′ of the plasma oxynitriding apparatus according to the first embodiment.
FIG. 3 is an exploded perspective view of a main part of the plasma oxynitriding apparatus shown in FIG.
FIG. 4A shows a slot shape of a slot plate (1).
(B) Slot shape of the slot plate (2).
FIG. 5 is an explanatory diagram showing a relationship between a thickness t of a circular slot plate 8 and a strain due to thermal deformation.
FIG. 6 is an explanatory diagram showing the relationship between the thickness t and the transmittance of each of the circular slot plates 8 having three types of slots having respective slot lengths.
FIG. 7 is an external view of a plasma oxynitriding apparatus according to the first embodiment.
FIG. 8 is a cross-sectional view of the device of FIG. 7 perpendicular to the X-axis in the drawing including BB ′ of FIG. 7;
9 is an exploded perspective view of a main part of the plasma oxynitriding apparatus shown in FIG.
FIG. 10 shows a slot shape of an H-plane slot antenna.
FIG. 11 is a perspective view of a rectangular slot plate 36 having a plurality of slots 36a.
FIG. 12A shows the shape of a slot in a rectangular slot plate (1).
(B) Shape of slot of rectangular slot plate (2).
13 (a) is an explanatory diagram showing the relationship between the slots in FIG. 12 (a) and the wavelengths of microwaves in the X and Y directions propagating in the antenna dielectric. FIG.
FIG. 13B is an explanatory diagram showing the relationship between the slots in FIG. 12B and the wavelengths of microwaves in the X and Y directions propagating in the antenna dielectric.
[Explanation of symbols]
REFERENCE SIGNS LIST 1 microwave generator 2 waveguide 3 coaxial antenna 4 chamber 4 a circular chamber lid 4 b circular processing chamber 7 resonator 8 circular slot plate 9 circular sealing dielectric 12 sample 20 rectangular waveguide 25 rectangular chamber 25 a rectangular chamber lid 25 b Rectangular processing chamber 30 H-plane slot antenna 34 Rectangular antenna dielectric 36 Rectangular slot plate 38 Rectangular sealing dielectric

Claims (9)

A plasma processing apparatus for performing plasma processing on a sample in a reactor,
Microwave generating means for generating microwaves,
A plurality of slots are provided between the microwave generating means and the reactor, and a plurality of slots are formed, and an electric field intensity distribution of the microwave generated from the microwave generating means is substantially uniform along a processing surface of the sample. A slot plate to
A first dielectric provided between the slot plate and the reactor, for maintaining or further improving the uniformity of the electric field intensity distribution of the microwave supplied from the slot plate;
Processing means for processing the sample using plasma generated in the reactor by the microwave,
A plasma processing apparatus wherein the thickness of the slot plate is 1 mm or more. 2. The plasma processing apparatus according to claim 1, wherein a second dielectric is further provided between said microwave generating means and said slot plate. 3. The plasma processing apparatus according to claim 1, wherein the thickness of the slot plate is 3 mm or more. The plasma processing apparatus L ₁ ≧ (3) according to claim 1, wherein the slot of the slot plate has a rectangular shape, and a length L ₁ of the slot in a long side direction substantially satisfies the following expression (1). 3/8) λ _A (1)
Here, λ _A : the wavelength of the microwave introduced into the slot plate. The plasma processing apparatus L ₁ ≧ (１ ／) λ _A (2) according to claim 4, wherein the length L ₁ of the slot in the long side direction substantially satisfies the following expression (2).
Here, λ _A : the wavelength of the microwave introduced into the slot plate. 6. The plasma processing apparatus according to claim 5, wherein the length L ₁ of the slot in the long side direction is substantially L ₁ = (１ ／) λ _A , wherein λ _A is introduced into the slot plate. The wavelength of the microwave to be applied. The plasma processing apparatus according to claim 2, wherein a cross section of the first dielectric and the second dielectric along a processing surface of the sample is rectangular. The same shape of the slot is approximately the same size, generally provided along the same direction, the distance L ₅ between the centers of adjacent said slot is _{substantially, L 5 = n L5 λ 2} , wherein Item 7. The plasma processing apparatus according to item 7, wherein [lambda] ₂ : a wavelength _nL5 of a microwave in the second dielectric: an integer of 1 or more. The slots are generally of the same size and shape, are arranged line-symmetrically with respect to any of the mutually orthogonal axes along the slot plate, and the distance L ₆ between the centers of adjacent slots is substantially L ₆ = a _{n L6 (λ 2/2)} , where the plasma processing apparatus according to claim 7, lambda _2: the second dielectric microwave wavelength _{n L6:} 1 or more integer.

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