Plasma processing equipment

Abstract

To suppress the propagation of electromagnetic waves in a top plate that constitutes a top wall of a processing vessel that a plasma processing device has.SOLUTION: The plasma processing device has: a processing vessel; a top plate that constitutes a top wall of the processing vessel, is formed from a first dielectric substance, and has an opening in the first dielectric substance; a transmission window disposed in the opening and formed from a second dielectric substance having a dielectric constant greater than that of the first dielectric substance; and an electromagnetic wave supply unit configured to supply electromagnetic waves toward the transmission window.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] Patent Document 1 discloses a plasma processing apparatus having an antenna that radiates microwaves into a processing chamber and a dielectric member that transmits the microwaves radiated from the antenna and forms surface waves. It proposes that the length of the closed circuit through which the surface current and displacement current flow be nλ0±δ (n is a positive integer, λ0 is the microwave wavelength, and δ is a fine-tuning component (including 0)). This increases the surface current and improves the plasma absorption efficiency, thereby increasing the rate of increase in electron density with increasing input power.

[0003] Patent Document 2 discloses a plasma processing apparatus comprising a processing chamber, a flat dielectric window, an induction coil, a flat electrode, a high-frequency power supply, a gas supply means, and a sample stage on which a sample is placed. A high-permittivity dielectric material is provided between the dielectric window and the processing gas supply plate. The generated electric field is absorbed by the high-permittivity dielectric material, resulting in a decrease in effective voltage and non-uniform electric field distribution. To prevent this, a notch is created in the Faraday shield above the dielectric window, weakening the electric field directly below the notch and uniforming the electric field distribution. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-175430 [Patent Document 2] Japanese Patent Application Laid-Open No. 2013-254723 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides a technique capable of suppressing propagation of electromagnetic waves within a top plate that constitutes a top wall of a processing chamber of a plasma processing apparatus. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a processing chamber including: a top plate constituting a top wall of the processing chamber, the top plate being made of a first dielectric and having an opening in the first dielectric; a transmission window being disposed in the opening and being made of a second dielectric having a dielectric constant greater than that of the first dielectric; and an electromagnetic wave supply unit configured to supply an electromagnetic wave toward the transmission window. The electromagnetic wave supply unit has an antenna unit that radiates the electromagnetic waves into the processing vessel, and the antenna unit is installed only on the transmission window. A plasma processing apparatus is provided. [Effects of the Invention]

[0007] According to one aspect, it is possible to suppress propagation of electromagnetic waves within a top plate that constitutes a top wall of a processing vessel of a plasma processing apparatus. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view showing an example of a plasma processing apparatus according to an embodiment; [Figure 2] FIG. 2 is a diagram showing an example of a microwave plasma source used in the plasma processing apparatus of FIG. [Figure 3] 2 is a diagram showing an example of the lower surface of the top plate of the plasma processing apparatus of FIG. 1. [Figure 4] 3A and 3B are diagrams schematically showing the arrangement of a transmission window and localization of plasma according to the embodiment. [Figure 5] 10A and 10B are diagrams illustrating the periphery of a top plate according to a reference example and an embodiment. [Figure 6] 10A and 10B are diagrams showing the electric field intensity distribution in the top plate according to the reference example and the embodiment. [Figure 7] 10A and 10B are diagrams showing the radius of the transmission window and the microwave propagation suppression effect according to the embodiment. [Figure 8] 10A and 10B are diagrams showing an example of the radius of the transmission window and the electric field intensity at the outer edge of the top plate according to the embodiment. [Figure 9]5A and 5B are diagrams showing an example of the dielectric constant of the transmission window and the electric field intensity at the outer edge of the top plate according to the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0010] In this specification, deviations in directions such as parallel, right angles, orthogonal, horizontal, vertical, up / down, left / right, etc. are permitted to the extent that they do not impair the effects of the embodiments. The shape of the corners is not limited to right angles and may be rounded like an arch. Parallel, right angles, orthogonal, horizontal, vertical, circle, cylinder, disk, and coincidence may also include approximately parallel, approximately right angles, approximately orthogonal, approximately horizontal, approximately vertical, approximately circle, approximately cylinder, approximately disk, and approximately coincidence.

[0011] [Plasma processing equipment] First, a configuration example of a plasma processing apparatus 100 according to an embodiment will be described with reference to Fig. 1 to Fig. 3. Fig. 1 is a cross-sectional view showing an example of the plasma processing apparatus 100 according to an embodiment. Fig. 2 is a diagram showing an example of a microwave plasma source 2 used in the plasma processing apparatus 100 of Fig. 1. Fig. 3 is a diagram showing an example of the underside of a top plate 111 of the plasma processing apparatus 100 of Fig. 1.

[0012] The plasma processing apparatus 100 performs plasma processing such as etching and film formation on a substrate W, e.g., a wafer. The plasma processing apparatus 100 includes an airtight processing chamber 1 made of a metal such as aluminum or stainless steel, and a microwave plasma source 2 configured to generate microwave plasma within the processing chamber 1. The processing chamber 1 is cylindrical and grounded. The top of the processing chamber 1 is open, and a support ring 29 is provided surrounding the opening. The microwave plasma source 2 is provided so as to face the interior of the processing chamber 1 through the opening.

[0013] A mounting table 11 for horizontally supporting a substrate W is provided within the processing vessel 1 and is supported by a cylindrical support member 12 that stands via an insulating member 12a at the center of the bottom of the processing vessel 1. The mounting table 11 and the support member 12 can be made of, for example, aluminum whose surface has been anodized (anodized).

[0014] Although not shown, the mounting table 11 is also provided with an electrostatic chuck for electrostatically attracting the substrate W, a temperature control mechanism, a heat transfer gas flow path for supplying a heat transfer gas to the backside of the substrate W, and lifting pins for lifting and lowering the substrate W. Furthermore, a high-frequency bias power supply 14 is electrically connected to the mounting table 11 via a matching box 13. When high-frequency power is supplied from the high-frequency bias power supply 14 to the mounting table 11, ions in the plasma are attracted toward the substrate W.

[0015] An exhaust pipe 15 is connected to the bottom of the processing vessel 1, and an exhaust device 16 including a vacuum pump is connected to the exhaust pipe 15. By operating the exhaust device 16, the processing vessel 1 is evacuated, and the pressure inside the processing vessel 1 can be quickly reduced to a predetermined vacuum level. In addition, a sidewall of the processing vessel 1 is provided with a load / unload port 17 for loading / unloading the substrate W, and a gate valve 18 for opening / closing the load / unload port 17.

[0016] The top plate 111 is supported by the support ring 29 at the top of the processing vessel 1 and closes the opening at the top of the processing vessel 1. As a result, the top plate 111 forms the ceiling wall of the processing vessel 1, and the processing vessel 1 and the top plate 111 define a plasma generation space U. The top plate 111 is made of a dielectric material with high plasma resistance. This prevents the top plate 111 from being damaged by microwaves radiated from the microwave plasma source 2, thereby suppressing the generation of particles and contamination.

[0017] The top plate 111 is disk-shaped (circular flat plate) and is made of a dielectric (hereinafter also referred to as a "first dielectric"). The first dielectric has a plurality of openings 111b. Into the openings 111b, there are fitted transmission windows 112 made of a dielectric (hereinafter also referred to as a "second dielectric") having a dielectric constant larger than that of the first dielectric.

[0018] The thickness of the second dielectric forming the transmission window 112 is the same as the thickness of the first dielectric forming the top plate 111. In other words, the surface of the second dielectric exposed to the plasma generation space U (i.e., the lower surface 111a) is flush with the surface of the first dielectric adjacent to the second dielectric exposed to the plasma generation space U. However, the entire surface of the first dielectric exposed to the plasma generation space U does not have to be flat; for example, a recess or the like may be present on a surface of the first dielectric other than the surface adjacent to the second dielectric. In addition, the surface opposite to the surface of the second dielectric exposed to the plasma generation space U is flush with the surface opposite to the surface of the first dielectric adjacent to the second dielectric exposed to the plasma generation space U.

[0019] Since the dielectric constant of the second dielectric is greater than that of the first dielectric, the transmission window 112 functions to confine the electromagnetic field of the microwave within the second dielectric when transmitting the microwave. For example, the first dielectric may be alumina (Al2O3) with a dielectric constant of about 9.6 or quartz with a dielectric constant of about 3.7 to 4, and the second dielectric may be a high-dielectric material such as zirconia with a dielectric constant of 30. The radius of the second dielectric and the range of possible dielectric constants will be described later.

[0020] The microwave plasma source 2 is disposed above the top plate 111. More specifically, the electromagnetic wave supply unit 43 included in the microwave plasma source 2 is disposed above the transmission window 112 formed of a second dielectric. With this configuration, the electromagnetic wave supply unit 43 supplies microwaves, which are an example of electromagnetic waves, toward the transmission window 112.

[0021] The periphery of the top plate 111 is covered with a backing member 110 made of a metal such as aluminum, except for the lower surface 111a and the portion supported by the support ring 29. The space between the support ring 29 and the backing member 110 is airtightly sealed.

[0022] As shown in Figures 1 and 2, the microwave plasma source 2 has a microwave output unit 30 that outputs microwaves by distributing them to multiple paths, and an antenna module 41 that transmits the microwaves output from the microwave output unit 30 and radiates them into the processing vessel 1.

[0023] As shown in FIG. 2, the microwave output unit 30 includes a microwave power supply 31, a microwave oscillator 32, an amplifier 33 that amplifies the oscillated microwave, and a distributor 34 that distributes the amplified microwave into multiple parts.

[0024] The microwave oscillator 32 generates microwaves of a predetermined frequency (for example, 915 MHz) by, for example, PLL oscillation. The distributor 34 distributes the microwaves amplified by the amplifier 33 while matching the impedance between the input and output sides to minimize microwave loss. Note that, in addition to 915 MHz, frequencies between 700 MHz and 3 GHz can also be used as the microwave frequency.

[0025] A plurality of antenna modules 41 are provided, and guide the microwaves distributed by distributor 34 into processing vessel 1. Each antenna module 41 has an amplifier unit 42 that mainly amplifies the distributed microwaves, and an electromagnetic wave supply unit 43. Furthermore, electromagnetic wave supply unit 43 has a tuner 60 (see FIG. 1) for impedance matching, and an antenna unit 113 that radiates the amplified microwaves into processing vessel 1. As shown in FIG. 1, the microwaves are radiated into processing vessel 1 from slits 113S of antenna unit 113 of each electromagnetic wave supply unit 43 in antenna module 41 through transmission window 112.

[0026] The amplifier section 42 includes a phase shifter 46, a variable gain amplifier 47, a main amplifier 48 constituting a solid-state amplifier, and an isolator 49. The phase shifter 46 is configured to change the phase of the microwave, and adjusting this phase shifter 46 can modulate the radiation characteristics. For example, adjusting the phase of each antenna module can control the directivity and change the plasma distribution. Also, by shifting the phase of adjacent antenna modules by 90°, circular polarization can be obtained. The phase shifter 46 can also be used to adjust the delay characteristics between components within the amplifier and for spatial synthesis within the tuner. However, if such modulation of the radiation characteristics or adjustment of the delay characteristics between components within the amplifier is not required, the phase shifter 46 is not necessary.

[0027] The variable gain amplifier 47 is an amplifier that adjusts the power level of the microwave input to the main amplifier 48 to adjust for variations in the individual antenna modules or to adjust the plasma intensity. By changing the variable gain amplifier 47 for each antenna module, it is also possible to create a distribution in the generated plasma.

[0028] The main amplifier 48, which constitutes a solid-state amplifier, can have, for example, an input matching circuit, a semiconductor amplifying element, an output matching circuit, and a high-Q resonant circuit. The isolator 49 separates the reflected microwaves that are reflected by the antenna unit 113 and head toward the main amplifier 48, and has a circulator and a dummy load (coaxial terminator). The circulator guides the microwaves reflected by the antenna unit 113 to the dummy load, and the dummy load converts the reflected microwaves guided by the circulator into heat.

[0029] 1, the electromagnetic wave supply unit 43 will be described. The electromagnetic wave supply unit 43 has a coaxial waveguide (microwave transmission line) 44 that transmits microwaves, and an antenna unit 113 that radiates the microwaves transmitted through the waveguide 44 into the processing vessel 1. The microwaves are radiated from the electromagnetic wave supply unit 43 into the processing vessel 1 through the antenna unit 113 and the transmission window 112, and are combined in the space within the processing vessel 1, thereby forming a surface wave plasma within the processing vessel 1.

[0030] The waveguide 44 is configured by arranging a cylindrical outer conductor 43b and a rod-shaped inner conductor 43a at the center of the outer conductor 43b coaxially, and an antenna unit 113 is provided at the tip of the waveguide 44. The inner conductor 43a is on the power feeding side, and the outer conductor 43b is on the ground side.

[0031] Microwave power is supplied to the space between the outer conductor 43b and the inner conductor 43a. Then, the microwave power propagates toward the antenna unit 113. In addition, a tuner 60 is provided in the waveguide 44. The tuner 60 matches the impedance of the load (plasma) in the processing vessel 1 to the characteristic impedance of the microwave power source in the microwave output unit 30. Specifically, the impedance is matched by moving two slugs 61a and 61b up and down between the outer conductor 43b and the inner conductor 43a.

[0032] The first dielectric forming the top plate 111 has a plurality of through holes. For example, when the bottom surface 111a of the top plate 111 is divided into a central portion that is a region including the center of the bottom surface 111a and an outer peripheral portion that is a region surrounding the central portion, a plurality of through holes open in the bottom surface 111a at equal intervals between the transmission window 112 in the central portion and the transmission window 112 in the outer peripheral portion, as shown in FIG.

[0033] As shown in FIGS. 1 and 3, a plurality of gas supply pipes 114 are fitted into the plurality of through holes. The gas supply pipes 114 are formed from a dielectric (hereinafter also referred to as a "third dielectric") having a smaller dielectric constant than the second dielectric of the transmission window 112. For example, the dielectric constant of the third dielectric is the same as that of the first dielectric. The third dielectric is hollow and may be formed from alumina, for example. The gas supply pipes 114 cause gas to flow through the hollow gas flow path, supplying the gas to the plasma generation space U. The plurality of gas supply pipes 114 penetrate the backing member 110 and are connected to a gas supply line 28, which is then connected to a gas supply unit 27.

[0034] The processing gas is supplied from the gas supply unit 27, passes through the gas supply line 28, and is introduced into the processing vessel 1 from the plurality of gas supply pipes 114. The introduced processing gas is excited in the plasma generation space U by the surface waves of the microwaves introduced into the processing vessel 1 from the microwave plasma source 2, and plasma of the processing gas is formed.

[0035] The electromagnetic wave supply unit 43 and the transmission window 112 are provided in one or more, and the same number of them are provided. FIG. 4 is a diagram schematically showing the arrangement of the transmission windows 112 and the localization of plasma according to the embodiment. In the example of FIGS. 3 and 4, the plasma processing apparatus 100 has seven electromagnetic wave supply units 43 and transmission windows 112, but the number is not limited to this. The electromagnetic wave supply unit 43 and the transmission window 112 are provided in the center and / or outer periphery of the top plate 111. In the example of FIGS. 3 and 4, six electromagnetic wave supply units 43 and six transmission windows 112 are arranged circumferentially on the outer periphery and one is arranged in the center.

[0036] [High dielectric constant transmission window] Conventionally, the top plate of a plasma processing apparatus 100 is made of a metal such as aluminum, and has a dielectric transmission window disposed in the opening of the top plate. In this case, when microwaves propagate through the transmission window, they also propagate to the metal surface of the top plate near the transmission window, causing a strong electric field, particularly at the corners of the metal surface of the top plate, damaging the top plate and causing metal peeling, resulting in particle generation and contamination. One method for eliminating the generation of particles and other contaminants is to construct the entire top plate 111 from a highly plasma-resistant dielectric material such as alumina. FIG. 5(a) is an enlarged view of the periphery of the top plate 111 according to a reference example, in which the entire top plate 111 is constructed from a dielectric material. This prevents electric field concentration on the top plate surface compared to a metal top plate, thereby reducing particle generation and contamination. Note that FIG. 5(a) is a diagram of a reference example used to facilitate understanding of the plasma processing apparatus 100 of this embodiment and is not intended to explain the prior art.

[0037] However, with the configuration of the top plate 111 of the reference example, the electromagnetic field of the microwaves transmitted through the dielectric material spreads radially within the top plate 111, making it difficult to generate plasma locally at the desired location, as shown in FIG. 4. In contrast, in this embodiment, a high-permittivity transmission window 112 is fitted into the opening of the top plate 111. FIG. 5(b) is an enlarged view of the periphery of the top plate 111 according to the embodiment. This configuration allows plasma to be generated locally at the desired location where the electric field directly below the multiple electromagnetic wave supply units 43 (antenna modules 41) is to be concentrated. For example, in the example of FIG. 4, plasma P1 is generated locally under one transmission window 112 located in the center, and plasmas P2 to P7 are generated locally under six transmission windows 112 arranged circumferentially and equidistantly around the periphery. As a result, plasmas P1 to P7 can be individually adjusted and independently controlled, allowing the distribution ratio of plasmas P1 to P7 to be controlled. This allows the desired plasma to be generated at the desired location in the plasma generation space U as a whole.

[0038] Hereinafter, local plasma generation will be described using as an example a plasma processing apparatus 100 in which the first dielectric of the top plate 111 is made of alumina and the second dielectric of the transmission window 112, where the microwave electric field is to be concentrated, is made of zirconia, which has a high dielectric constant. However, the materials of the first dielectric and the second dielectric are not limited to these. By embedding the second dielectric, which has a higher dielectric constant than the first dielectric, in the top plate 111, the microwave electromagnetic field can be confined within the transmission window 112, which has a high dielectric constant. This makes it possible to provide a plasma processing apparatus 100 that can concentrate the microwave electric field directly below the transmission window 112 and generate local plasma below the transmission window 112 (see FIG. 4).

[0039] [Simulation result 1] The radius r and the dielectric constant ε of the second dielectric material of the transmission window 112 r The results of a simulation for obtaining an appropriate value in this range will be described with reference to FIG. 6. FIG. 6 is a diagram showing the results 1 of simulating the electric field strength distribution in the tabletop 111 according to the reference example of FIG. 5(a) and the embodiment of FIG. 5(b). FIG. 6(b) is an enlarged view of the dotted frame in FIG. 6(a). (1) shown in FIGS. 6(a) and (b) shows the results of simulating the electric field strength in the tabletop 111 of the reference example of FIG. 5(a). In the reference example, the entire tabletop 111 is made of alumina with a dielectric constant of approximately 9.6.

[0040] 6(a) and 6(b) show the results of simulating the electric field intensity within the top plate 111 of the embodiment shown in FIG. 5(b). In this embodiment, the first dielectric of the top plate 111 is made of alumina with a dielectric constant of approximately 9.6, and the second dielectric of the transmission window 112 is made of zirconia with a dielectric constant of approximately 30. The radius r of the second dielectric is set to 60 mm. As shown in FIG. 5(b), the radius r of the second dielectric is the radius of the surface of the transmission window 112 (second dielectric) exposed to the plasma generation space U. In FIGS. 1 and 5(b), the transmission window 112 has a step on its side so that the radius of the upper part is larger than the radius of the lower part. However, the transmission window 112 may be cylindrical without any step. Other simulation conditions include setting the frequency of the supplied microwave to 860 MHz.

[0041] 6 indicates the radial position of the top plate 111, with axis Ax passing through the center of the central electromagnetic wave supply unit 43 (and the transmission window 112) shown in FIGS. 5(a) and (b) at a position 200 mm from the end of the top plate 111 (the center of FIG. 6(a)). Axis Ax coincides with the central axis of the top plate 111.

[0042] The vertical axis in Fig. 6 shows the electric field strength on line L drawn in the radial direction within tabletop 111 shown in Figs. 5(a) and (b), normalized to "1" as the electric field strength at the position where line L intersects with axis Ax, which has the highest electric field strength. Line L is an imaginary line (straight line) extending in the radial direction of tabletop 111 at approximately the center in the thickness direction of tabletop 111. However, line L does not have to be a straight line drawn at approximately halfway through the thickness of tabletop 111, as long as it is a straight line extending horizontally in the radial direction within tabletop 111.

[0043] In the simulation results of Fig. 6(a), in the embodiment (2), the transmission window 112 (second dielectric) with a radius r of 60 mm has a diameter of 120 mm and is located in the range of approximately 140 mm to approximately 260 mm shown on the horizontal axis of Fig. 6(a). In the range of 140 mm to 260 mm shown on the horizontal axis of Fig. 6(a), the electric field strength of the embodiment (2) is higher than that of the reference example (1). On the other hand, in Fig. 6(b), which shows an enlarged view of one outer edge (0 mm to 140 mm) shown in Fig. 6(a), the electric field strength of the embodiment (2) is lower than that of the reference example (1).

[0044] As a result, in the configuration of the top plate 111 according to this embodiment, by embedding the transmission window 112 formed from the second dielectric material with a high dielectric constant inside the top plate 111, it is possible to confine the microwave electromagnetic waves inside the transmission window 112. This makes it possible to prevent the microwave electromagnetic waves supplied from the electromagnetic wave supply unit 43 from leaking beyond the transmission window 112 to the top plate 111 side of the outer edge.

[0045] [Simulation result 2] Next, the results of the microwave propagation suppression effect when the radius r of the second dielectric is set to be variable will be described with reference to FIG. 7. FIG. 7 is a diagram showing result 2 obtained by simulation of the microwave propagation suppression effect when the radius r of the second dielectric of the transmission window 112 according to the embodiment is set to be variable. The other simulation conditions are the same as those for obtaining the results of FIG. 6. FIG. 7(b) is an enlarged view of the area within the dotted line frame in FIG. 7(a). The horizontal and vertical axes of FIGS. 7(a) and 7(b) are the same as those of FIG. 6. In FIGS. 7(a) and 7(b), (1) shows the electric field intensity at line L (see FIG. 5(b)) when the radius r of the second dielectric of the transmission window 112 is 50 mm, and (2) shows the electric field intensity at line L when the radius r of the second dielectric is 70 mm.

[0046] This shows that the electric field distribution changes depending on the radius r of the second dielectric of the transmission window 112. However, in both cases where the radius r is 50 mm and 70 mm, embedding the transmission window 112 of the second dielectric in the top plate 111 results in a high electric field distribution inside the second dielectric and a significantly low electric field distribution at its outer edge. In other words, microwave electromagnetic waves can be confined inside the second dielectric. For example, when the radius r of the second dielectric is 50 mm, the electric field strength inside the second dielectric at a diameter of 100 mm (150 mm to 250 mm) is high, and the electric field strength inside the first dielectric at an outer edge of 250 mm is suppressed. Similarly, when the radius r of the second dielectric is 70 mm, the electric field strength inside the second dielectric at a diameter of 140 mm (130 mm to 270 mm) is high, and the electric field strength inside the first dielectric at an outer edge of 270 mm is suppressed.

[0047] This makes it possible to prevent the microwaves supplied from the electromagnetic wave supply unit 43 from leaking toward the top plate 111 of the first dielectric at the outer edge of the transmission window 112. As described above, when multiple transmission windows 112 are arranged on the top plate 111, the electromagnetic waves are confined within the high-dielectric body of each transmission window 112, so there is no influence from microwaves passing through adjacent transmission windows 112. Therefore, adjacent transmission windows 112 only need to be separated from each other by the first dielectric, and the thickness of the first dielectric provided between adjacent transmission windows 112 does not matter. In other words, when multiple transmission windows 112 are arranged in the opening 111b of the top plate 111, the thickness of the first dielectric of the top plate 111 between the multiple transmission windows 112 may be thin.

[0048] [Simulation result 3] Next, the results of a simulation for obtaining an appropriate value for the radius r of the second dielectric will be described with reference to Fig. 8. The horizontal axis of Fig. 8(a) represents the dielectric constant ε of the second dielectric of the transmission window 112. r8(b) shows the radius r of the second dielectric when it is made of zirconia with a diameter of 30. The horizontal axis of FIG. 8(b) shows the normalized electric field intensity at the outer edge 188 mm from the center (12 mm from the edge of the top plate 111), with the axis Ax being the center (200 mm) of the top plate 111 and the electric field intensity at the position of the axis Ax being 1. The simulation conditions for FIG. 8 differ from those for FIG. 6 only in that the material of the second dielectric was changed; the other simulation conditions were the same as the simulation conditions for obtaining the results of FIG. 6.

[0049] λ shown on the horizontal axis of FIG. 8(a) is the effective wavelength of the microwave in the second dielectric of the transmission window 112, and the dielectric constant ε r When the second dielectric is made of zirconia with a diameter of 30 mm, the effective wavelength λ of the microwaves in the second dielectric is 63.7 mm. According to the simulation results of FIG. 8(a), it is preferable to configure the zirconia second dielectric so that its radius r is in the range of λ / 2≦r≦3λ / 2. This sufficiently suppresses the spread of microwave electromagnetic waves from the second dielectric of the transmission window 112 to the first dielectric at the outer edge, thereby sufficiently reducing the electric field strength at the outer edge.

[0050] In Fig. 8(b), the dielectric constant ε r This figure shows the relationship between the radius r of the second dielectric and the normalized electric field strength when the second dielectric is made of titanium oxide with a surface roughness of 100. In Figure 8(b), the horizontal axis shows the radius r of the second dielectric made of titanium oxide, and the vertical axis shows the normalized electric field strength at the outer edge 188 mm from the center, with the electric field strength at the center position of the axis Ax being 1.

[0051] Dielectric constant ε rAs the radius r increases, the effective wavelength λ of the microwaves propagating through the second dielectric becomes shorter. In the case of titanium oxide, the effective wavelength λ of the microwaves in the second dielectric is 34.9 mm. According to the simulation results of FIG. 8(b), it is preferable that the radius r of the second dielectric made of titanium oxide is also configured to be in the range of λ / 2≦r≦3λ / 2. This sufficiently suppresses the spread of microwave electromagnetic waves from the second dielectric of the transmission window 112 to the first dielectric at the outer edge, thereby sufficiently reducing the electric field strength at the outer edge.

[0052] 8(a) and 8(b), when the radius r of the second dielectric satisfies the condition λ / 2≦r≦3λ / 2, it is possible to prevent the electromagnetic field of the microwave from spreading from the second dielectric of the transmission window 112 to the first dielectric at the outer edge. This increases the electric field intensity below the transmission window 112, making it possible to generate localized plasma.

[0053] [Simulation result 4] FIG. 9 shows the dielectric constant ε of the second dielectric constituting the transmission window 112 according to the embodiment. r 9(a) shows an example of the electric field intensity at the outer edge 188 mm from the position of the axis Ax. The horizontal axis of FIG. 9(a) is the dielectric constant ε of the second dielectric of the transmission window 112. r 8(b), the horizontal axis represents the normalized electric field intensity at the outer edge 188 mm from the center, when the electric field intensity at the center position (200 mm) of the tabletop 111 on the axis Ax is set to 1. The simulation conditions in FIG. 9 differ from those in FIG. 8 only in that the dielectric constant of the second dielectric was changed, and the other simulation conditions are the same as those for obtaining the results in FIG. 8.

[0054] According to this, the dielectric constant ε of the second dielectric material constituting the transmission window 112 r By making the dielectric constant ε of the second dielectric material 30 or more, rCompared to when the value is set to 20, the microwave electromagnetic waves can be confined within the transmission window 112. This makes it possible to prevent the electromagnetic field from spreading to the outer edge of the transmission window 112, concentrate the electric field below the transmission window 112, and generate localized plasma below the transmission window 112.

[0055] Therefore, from the simulation results of FIG. 9, for the first dielectric of alumina with a dielectric constant of 9.6, the dielectric constant ε r is required to be at least three times the dielectric constant of the first dielectric of the top plate 111, and is preferably at least three times but no more than ten times, since this can prevent the electromagnetic field generated by the microwaves from spreading to the outer edge outside the transmission window 112.

[0056] The second dielectric of the transmission window 112 is preferably a high dielectric constant material having a dielectric constant of 30 or more and 100 or less. Therefore, the second dielectric of the transmission window 112 may be zirconia having a dielectric constant of 30 or titanium oxide having a dielectric constant of 100. Depending on the first dielectric, sapphire may also be used for the second dielectric of the transmission window 112.

[0057] Furthermore, the dielectric constant ε of the second dielectric of the transmission window 112 r It is more preferable that the dielectric constant of the first dielectric of the top plate 111 is three to four times that of the first dielectric of the top plate 111, since this can more sufficiently prevent the electromagnetic field from spreading to the outer edge portion outside the transmission window 112. Therefore, the transmission window 112 may be made of zirconia with a dielectric constant of 30 to 40.

[0058] As described above, according to the plasma processing apparatus 100 of this embodiment, the transmission window 112 made of a high dielectric constant material is provided at a location where the electric field is desired to be concentrated inside the top plate 111 constituting the top wall of the processing chamber 1. That is, the second dielectric of the transmission window 112 is made of a high dielectric constant material having a dielectric constant greater than the dielectric constant of the first dielectric of the top plate 111. This confines the electric field generated by the microwave within the transmission window 112, and prevents the microwave propagation from spreading outside the transmission window 112. Therefore, the electric field strength can be suppressed at the outer edge outside the transmission window 112.

[0059] The plasma processing apparatus according to the presently disclosed embodiments should be considered in all respects as illustrative and not restrictive. The embodiments can be modified and improved in various ways without departing from the spirit and scope of the appended claims. The features described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0060] The plasma processing apparatus of the present disclosure can be applied to a radial line slot antenna apparatus. [Explanation of symbols]

[0061] 1. Processing container 2. Microwave plasma source 27 Gas Supply Section 41 Antenna Module 43 Electromagnetic wave supply section 100 Plasma processing device 110 Backing member 111 Top plate 112 Transparent window 114 Gas supply pipe

Claims

1. A processing vessel; a top plate that constitutes a top wall of the processing vessel and is formed from a first dielectric material, the top plate having an opening in the first dielectric material; a transmission window disposed in the opening and formed from a second dielectric material having a dielectric constant greater than that of the first dielectric material; an electromagnetic wave supply unit configured to supply an electromagnetic wave toward the transmission window; and the electromagnetic wave supply unit has an antenna unit that radiates the electromagnetic wave into the processing vessel, The plasma processing apparatus is such that the antenna unit is installed only on the transmission window.

2. the processing chamber and the top plate define a plasma generation space; a surface of the second dielectric exposed to the plasma generation space is flush with a surface of the first dielectric adjacent to the second dielectric exposed to the plasma generation space; The plasma processing apparatus according to claim 1 .

3. The electromagnetic wave supply unit and the transmission window are one or more, and the same number of them are installed.

3. The plasma processing apparatus according to claim 1 or 2.

4. The electromagnetic wave supply unit and the transmission window are installed in the central portion and / or the outer periphery of the top plate. The plasma processing apparatus according to claim 3 .

5. When an effective wavelength of the electromagnetic wave in the second dielectric is λ, the transmission window is configured so that a radius r of a surface of the second dielectric exposed to a plasma generation space is in a range of λ / 2≦r≦3λ / 2. The plasma processing apparatus according to claim 1 .

6. The dielectric constant of the second dielectric is three times or more the dielectric constant of the first dielectric. The plasma processing apparatus according to claim 1 .

7. The dielectric constant of the second dielectric is 3 times or more and 10 times or less than the dielectric constant of the first dielectric. The plasma processing apparatus according to claim 6 .

8. The dielectric constant of the second dielectric is three to four times the dielectric constant of the first dielectric. The plasma processing apparatus according to claim 7 .

9. The transmission window is provided in plurality, the thickness of the first dielectric interposed between the second dielectrics forming the transmission windows is a thin film; The plasma processing apparatus according to claim 1 .

10. the second dielectric is a high dielectric constant material having a dielectric constant of 30 or more and 100 or less; The plasma processing apparatus according to claim 1 .

11. The first dielectric has a plurality of through holes; a plurality of gas supply pipes arranged in the plurality of through holes, each gas supply pipe being formed from a hollow third dielectric having a dielectric constant smaller than that of the second dielectric, and configured to cause a gas to flow within the third dielectric; The plasma processing apparatus according to claim 1 .

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