Plasma generating device and cooling case

Abstract

The plasma generating apparatus according to the present invention comprises: a microwave generating source for generating microwaves; a plasma generation tube having a cylindrical shape in which the gas, which has been ionized by the microwaves, flows; a waveguide tube that transmits the microwaves generated from the microwave generation source to the plasma generation tube; the matcher is arranged on the waveguide tube between the microwave generation source and the plasma generation tube; the cooling sleeve is arranged on the peripheral surface of the outer side of the plasma generating tube and is used for cooling the plasma generating tube; and a housing having a cylindrical shape and accommodating the plasma generation tube and the cooling jacket, the cooling jacket having: three slits extending in the traveling direction of the gas flowing in the plasma generation tube and allowing the microwaves to pass through the plasma generation tube; and a cooling flow path provided between the slits adjacent to each other, in which a cooling fluid that cools the plasma generation tube flows.

Description

Technical Field

[0001] The present invention relates to a plasma generating device and a cooling jacket. Background Art

[0002] Conventionally, when processing a workpiece or forming a thin film using a gas in a plasma state, a plasma generating device that makes a specified gas into a plasma state by microwaves is used.

[0003] Examples of the plasma generating device include a plasma generating device including a plasma generating tube through which a gas to be plasmaized flows and a microwave generating source that generates microwaves for plasmaizing the gas flowing in the plasma generating tube.

[0004] When a gas is plasmaized, heat is generated, and there is a risk that the plasma generating tube is damaged by being heated by this heat. Therefore, as shown in Patent Document 1, for example, this type of plasma generating device also includes a cooling jacket for cooling the plasma generating tube. The cooling jacket includes: four or more slits formed along the traveling direction of the gas flowing in the plasma generating tube, allowing microwaves irradiated from the outside of the plasma generating tube to pass through; and a plurality of columnar flow channels formed between adjacent slits for a cooling fluid to flow through. With this structure, the microwaves generated from the microwave generating source pass through the slits to plasmaize the gas flowing in the plasma generating tube, and the plasma generating tube is cooled by the cooling fluid flowing in the columnar flow channels. Therefore, it is possible to prevent the plasma generating tube from being damaged by the heat during plasmaization. Prior Art Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2020-205172

[0006] Conventionally, it has been considered that if the number of slits of the cooling jacket increases, the area through which microwaves pass to the plasma generating tube increases, so that plasma can be generated efficiently.

[0007] On the other hand, for example, in a cooling jacket having eight slits, as Figure 6 shown, the resonance frequency of the cooling jacket and the housing is 4 GHz. Since this resonance frequency deviates from the frequency of the microwaves, it takes time to adjust the resonance impedance of the cooling jacket and the housing to match the impedance of the microwave generating source, and there is a burden during the matching adjustment by the matcher. Summary of the Invention

[0008] Here, the main object of the present invention is to enable the matcher to operate quickly and reduce the burden on the matcher in a plasma generating device that plasmaizes a gas using microwaves.

[0009] In order to solve the above problems, as a result of the earnest exploration by the present inventors, it has been first discovered that if a cooling sleeve having three slits is used, the resonance frequencies of the cooling sleeve and the housing are near the frequency of microwaves, thus achieving the present invention.

[0010] That is, the plasma generating device of the present invention includes: a microwave generating source that generates microwaves; a plasma generating tube that is cylindrical and through which a gas to be plasmaized by the microwaves flows inside; a waveguide that connects the microwave generating source and the plasma generating tube and transmits the microwaves to the plasma generating tube; a matcher that is provided in the waveguide between the microwave generating source and the plasma generating tube; a cooling sleeve that is provided on the outer circumferential surface of the plasma generating tube and is used to cool the plasma generating tube; and a housing that is cylindrical and houses the plasma generating tube and the cooling sleeve. The cooling sleeve has: three slits that extend along the traveling direction of the gas flowing in the plasma generating tube or extend obliquely with respect to the traveling direction, allowing the microwaves to pass through to the plasma generating tube; and a cooling flow path that is formed between the adjacent slits and through which a cooling fluid for cooling the plasma generating tube flows.

[0011] According to such a plasma generating device, since the cooling sleeve has three slits, the resonance frequencies of the cooling sleeve and the housing exist near 2.45 GHz. As a result, the deviation between the frequency of the microwaves and this resonance frequency is smaller than before, so the adjustment time for making the resonance impedance of the cooling sleeve and the housing consistent with the impedance of the microwave generating source can be shortened, and the burden during the matching adjustment of the matcher can be reduced.

[0012] Preferably, the slits extend along a direction perpendicular to the vibration direction of the electric field of the microwaves or extend obliquely with respect to the perpendicular direction, and the cross section of the waveguide is rectangular, and the long side forming the rectangle extends along the direction in which the slits extend or extends obliquely with respect to the extending direction.

[0013] According to such a structure, the slits are formed along a direction perpendicular to the vibration direction of the electric field of the microwaves, and the long side of the rectangle forming the cross section of the waveguide extends along the direction in which the slits extend. Therefore, the reflection of the microwaves on the cooling sleeve is suppressed, and the microwaves can pass through the slits efficiently. As a result, the microwaves are appropriately irradiated on the plasma generating tube, so that the gas flowing inside the plasma generating tube can be plasmaized efficiently.

[0014] Preferably, at least two of the three slits face the microwave generating source.

[0015] According to this structure, at least two slits face the microwave generation source. Therefore, compared with the case where only one slit faces the microwave generation source, the microwaves generated from the microwave generation source can be efficiently transmitted to the plasma generation tube. As a result, the gas flowing inside the plasma generation tube can be efficiently ionized.

[0016] In the circumferential direction of the plasma generation tube, in order to uniformly ionize the gas flowing inside, it is also necessary to make the microwaves pass from the side opposite to the microwave generation source. Here, it can be cited that a reflector is further provided, which is disposed in the waveguide opposite to the microwave generation source with the plasma generation tube interposed therebetween, reflects the microwaves from the microwave generation source toward the plasma generation tube, at least one of the three slits is formed facing the reflector, and at least one of the other slits is formed facing the microwave generation source.

[0017] According to this structure, in the cooling jacket having three slits, one slit formed facing the reflector allows the microwaves reflected from the reflector to pass through to the plasma generation tube, and the other slit allows the microwaves generated from the microwave generation source to pass through to the plasma generation tube. As a result, in the circumferential direction of the plasma generation tube, the gas flowing inside can be uniformly ionized.

[0018] Preferably, the housing is formed with an observation window for observing the internal state of the plasma generation tube.

[0019] According to this structure, by forming an observation window for observing the internal state of the plasma generation tube on the housing, the plasma generated inside the plasma generation tube, for example, can be visually recognized through the observation window, and the temperature of the plasma generation tube can be confirmed by, for example, setting a thermometer on the observation window. As a result, both the prevention of microwave emission to the outside and the observation of the internal state of the plasma generation tube can be achieved.

[0020] Preferably, the housing is configured to be divisible into a plurality of components.

[0021] According to this structure, since the housing is configured to be divisible into a plurality of components, the loading, unloading, and assembly of the housing become easy.

[0022] Preferably, the plasma generation tube is composed of yttrium oxide, quartz coated with yttrium oxide, and / or a sapphire tube, or a combination thereof.

[0023] According to this structure, when fluorine-containing gas is ionized, the generation of by-products can be prevented.

[0024] Preferably, the plasma generating device further includes a plurality of plasma detection units, which are arranged opposite to the direction of the slit opening, and detect the light emission intensity of the plasma generated inside the plasma generating tube.

[0025] With this structure, the plurality of plasma detection units are arranged opposite to the direction of the slit opening. Therefore, the plurality of plasma detection units can detect the light emission intensity of the plasma generated inside the plasma generating tube through the slit. Moreover, based on the light emission intensity of the plasma detected by the plurality of plasma detection units, the distribution state of the plasma inside the plasma generating tube can be known. Thus, the user can detect the defective lighting state of the plasma according to the distribution state of the plasma.

[0026] Inside the plasma generating tube, the non-uniformity of the plasma distribution state in the direction along the gas traveling direction is greater than that in the direction intersecting the gas traveling direction. Here, it is preferable that the plurality of plasma detection units are arranged along the gas traveling direction.

[0027] With this structure, the plurality of plasma detection units are arranged along the gas traveling direction. Therefore, it is possible to reliably grasp the plasma distribution state in the direction where the possibility of greater non-uniformity is higher, and thus the defective lighting state of the plasma can be reliably detected.

[0028] In the plasma distribution state inside the plasma generating tube along the gas traveling direction, in order to detect the defective lighting state of the plasma, it is important to detect the light emission intensity of the plasma in the central part of the plasma generating tube. Here, it is preferable that the plurality of plasma detection units respectively detect the light emission intensity of the plasma in the upper part, the central part, and the lower part of the plasma generating tube in the gas traveling direction.

[0029] With this structure, at least a part of the plurality of plasma detection units detect the light emission intensity of the plasma in the central part of the plasma generating tube. Therefore, the defective lighting state of the plasma can be detected more reliably. In addition, other plasma detection units detect the light emission intensity of the plasma in the upper and lower parts of the plasma generating tube. Therefore, in the gas traveling direction, the plasma distribution state of the entire inside of the plasma generating tube can be accurately grasped.

[0030] In addition, the cooling sleeve provided by the present invention is disposed on the outer circumferential surface of the plasma generation tube. The plasma generation tube is cylindrical, and the gas that is plasmaized by microwaves flows inside. The cooling sleeve is used to cool the plasma generation tube, and is characterized in that it includes: three slits formed along the traveling direction of the gas flowing in the plasma generation tube, allowing the microwaves to pass through to the plasma generation tube; and cooling channels formed between the adjacent slits, and the cooling fluid for cooling the plasma generation tube flows in the cooling channels.

[0031] According to this structure, the same effects as those of the above-described plasma generation device can be obtained.

[0032] In addition, the cooling sleeve provided by the present invention is disposed on the outer circumferential surface of the plasma generation tube. The plasma generation tube is cylindrical, and the gas that is plasmaized by microwaves flows inside. The cooling sleeve is used to cool the plasma generation tube, and is characterized in that it includes: a slit extending along a direction perpendicular to the vibration direction of the electric field of the microwaves or extending obliquely with respect to the perpendicular direction, allowing the microwaves to pass through to the plasma generation tube; and a cooling channel provided separately from the slit, and the cooling fluid for cooling the plasma generation tube flows in the cooling channel. The cross-section of the waveguide is rectangular, and the long side forming the rectangle extends along the direction in which the slit extends or is inclined with respect to the extending direction.

[0033] According to this structure, the microwaves pass through by means of the slit, and thus the microwaves can be efficiently irradiated to the plasma generation tube.

[0034] In the plasma generation device of the present invention according to this structure, in the plasma generation device in which gas is plasmaized by microwaves, the matcher can be operated quickly, thereby reducing the burden on the matcher. Description of the Drawings

[0035] Figure 1 is a schematic diagram of a plasma generation device according to an embodiment of the present invention. Figure 2 is a front view of the plasma generation device of the same embodiment. Figure 3 is a cross-sectional view taken along line A-A of the plasma generation device of the same embodiment. Figure 4 is a cross-sectional view taken along line B-B of the plasma generation device of the same embodiment. Figure 5 is a schematic diagram (a) when the housing is installed and (b) when the housing is removed of the plasma generation device of the same embodiment. Figure 6 shows the measurement results of the relationship between the number of slits and the resonance frequency. Figure 7 It is a diagram comparing the etching rate in a cooling sleeve with three slits and the etching rate in a cooling sleeve with eight slits. Figure 8 It is a diagram showing a cooling sleeve with three slits in various ways. Figure 9 It is a side view of a plasma generating device in other embodiments. Figure 10 It is a C-C cross-sectional view of a plasma generating device in other embodiments. Detailed Embodiment

[0036] Hereinafter, an embodiment of the plasma generating device of the present invention will be described with reference to the accompanying drawings. In addition, for ease of understanding, any of the diagrams shown below may be schematically depicted with appropriate omissions or exaggerations. The same reference numerals are assigned to the same structural components and the description is appropriately omitted.

[0037] The plasma generating device 100 of the present embodiment plasmatizes the gas by irradiating the gas with microwaves.

[0038] Specifically, as shown in Figure 1 or Figure 3 The plasma generating device 100 includes: a microwave generating source 2 that generates microwaves; a plasma generating tube 3 through which the gas plasmatized by the microwaves flows; a waveguide 4 that transmits the microwaves; a reflector 5 that reflects the microwaves; a matcher 6 provided on the waveguide 4; a cooling sleeve 7 that cools the plasma generating tube 3; and a housing 8 that houses the plasma generating tube 3 and the cooling sleeve 7. Hereinafter, each part will be described.

[0039] The microwave generating source 2 generates microwaves for plasmatizing the gas flowing in the plasma generating tube 3. Specifically, the microwave generating source 2 is composed of, for example, a magnetron. The frequency of the microwaves generated from the microwave generating source 2 is, for example, 300 MHz or more and 300 GHz or less (preferably 2.45 GHz), the wavelength of the microwaves generated from the microwave generating source 2 is, for example, 1 mm or more and 1 m or less (preferably about 12 cm), and the oscillation output of the microwaves is, for example, 1 kW or more and 10 kW or less.

[0040] The plasma generating tube 3 has a substantially cylindrical shape, and the gas plasmatized by the microwaves flows inside. The plasma generating tube 3 is made of, for example, yttrium oxide, but is not limited thereto. For example, the plasma generating tube 3 may be made of quartz and / or sapphire tubes coated with yttrium oxide or a combination thereof in addition to yttrium oxide.

[0041] Here, when the traveling direction of the gas flowing inside the plasma generating tube 3 is set to the vertical direction, as shown in Figure 2 andFigure 3 As shown, the upper end of the plasma generation tube 3 is connected to the gas inlet P1, and the gas to be plasmaized flows into the plasma generation tube 3 from a gas supply source (not shown) that supplies the gas through the gas inlet P1. The gas supplied to the gas inlet P1 flows through the inside of the plasma generation tube 3, and the plasmaized gas is discharged from the lower end of the plasma generation tube 3 to a processing chamber (not shown). Also, hereinafter, the vertical direction is set as the traveling direction of the gas flowing inside the plasma generation tube 3.

[0042] In addition, the composition of the gas supplied from the gas supply source is appropriately selected according to the processing in the processing chamber (not shown). Examples of the gas composition include SF6, He, Ar, NF3, H2, O2, N2, NF3, Cl2, HCl, NH3, CF4, C2F6, C3F8, C4F8, Cl3F, N2O, or H2O, etc.

[0043] The waveguide 4 is, for example, a rectangular waveguide formed in a hollow quadrangular prism shape, and transmits the microwave generated from the microwave generation source 2 to the plasma generation tube 3. Specifically, the waveguide 4 connects the opening 8a formed on the housing 8 facing the microwave generation source 2 to the microwave generation source 2 and extends in a direction perpendicular to the vertical direction.

[0044] In addition, the waveguide 4 extends from the opening 8b formed on the housing 8 facing the side opposite to the microwave generation source 2 in a direction perpendicular to the vertical direction, and a reflector 5 is provided inside the waveguide 4. Specifically, the reflector 5 reflects the microwave generated from the microwave generation source 2 toward the plasma generation tube 3, and the reflector 5 has a reflecting surface 5a disposed opposite to the microwave generation source 2 with the plasma generation tube 3 interposed therebetween.

[0045] In addition, the surface opposite to the reflecting surface 5a is connected to a rod L, and the rod L is used to move the reflector 5 in a direction perpendicular to the vertical direction. By moving the rod L, the reflection position of the microwave is controlled. In addition, the reflection position of the microwave is controlled by an actuator (not shown) to form a standing wave in the waveguide 4.

[0046] The matcher 6 is provided on the waveguide 4 between the microwave generation source 2 and the plasma generation tube 3 and is used for matching to make the resonance impedance of the cooling sleeve 7 and the housing 8 consistent with the impedance of the microwave generation source 2. Specifically, the matcher 6 has a plurality of stubs. Each stub is configured to be able to adjust the protruding amount with respect to the internal space of the waveguide 4, and by adjusting the protruding position of each stub with respect to the reference position, the impedance of the microwave generation source 2 is matched with the resonance impedance of the cooling sleeve 7 and the housing 8.

[0047] The cooling sleeve 7 is in a hollow cylindrical shape and is provided on the outer peripheral surface of the plasma generation tube 3 for cooling the plasma generation tube 3. Specifically, asFigure 3 As shown in Figure 3 , the cooling jacket 7 includes: three slits 71 that extend in the vertical direction and allow microwaves to pass through to the plasma generation tube 3; cooling channels 72 that are provided between adjacent slits 71 and through which a cooling fluid for cooling the plasma generation tube 3 flows; and heat transfer members 73 that are interposed between the cooling channels 72 and the plasma generation tube 3 and transfer the cold air in the cooling channels 72 to the plasma generation tube 3. In addition, the upper and lower portions of the cooling jacket 7 are respectively supported by an upper support member S1 and a lower support member S2.

[0048] Each of the three slits 71 is substantially rectangular and penetrates from the outer circumferential surface to the inner circumferential surface of the cooling jacket 7. One slit here means that the slit in the case where the cooling jacket 7 and the housing 8 resonate from the upper end portion to the lower end portion of the cooling jacket 7 is referred to as one slit. By forming three slits 71 in the cooling jacket 7, the cooling jacket 7 and the housing 8 resonate near the frequency of the microwave generation source 2. In the present embodiment, when the frequency of the microwave generation source 2 is 2.45 GHz, the vicinity of the frequency of the microwave generation source 2 means 2.25 GHz or more and 2.65 GHz or less (more preferably 2.40 GHz or more and 2.50 GHz or less). Alternatively, when the frequency of the microwave generation source 2 is not 2.45 GHz, it means a frequency that is 90% or more and 110% or less (more preferably 97% or more and 103% or less) with respect to the frequency of the microwave generation source 2.

[0049] In the present embodiment, the three slits 71 are formed from the upper end portion to the lower end portion of the cooling jacket 7 and are arranged along the circumferential direction of the cooling jacket 7. Specifically, the electric field of the microwave generated from the microwave generation source 2 vibrates in a direction perpendicular to the vertical direction, and each slit 71 extends in a direction perpendicular to the vibration direction of the electric field of the microwave. More specifically, the long side direction of each slit 71 extends parallel to the long side of the rectangle constituting the waveguide 4. In addition, the shape of each slit 71 is not limited to a rectangle and may be an elongated shape such as an elliptical shape, for example. Further, in the present embodiment, each slit 71 has the same shape, but they may also have different shapes from each other, and the lengths in the long side direction of each slit 71 may be different lengths.

[0050] In addition, at least two of the three slits 71 face the microwave generation source 2. Specifically, as Figure 4 shown, two of the three slits 71, namely 71a and 71b, face the microwave generation source 2, and the remaining one slit 71c faces the reflecting surface 5a of the reflector 5. In this way, the slits 71a and 71b allow the microwave generated from the microwave generation source 2 to directly pass through to the plasma generation tube 3, and the slit 71c allows the microwave generated from the microwave generation source 2 to pass through to the plasma generation tube 3 via the reflecting surface 5a.

[0051] Moreover, between adjacent slits 71, there are formed beam-shaped regions 71z parallel to each slit 71. The beam-shaped regions 71z are formed from the upper end portion to the lower end portion of the cooling sleeve 7. Inside the beam-shaped regions 71z, there are provided cooling channels 72.

[0052] The cooling channels 72 are substantially cylindrical, and are formed from the upper end portion to the lower end portion of the cooling sleeve 7 along the vertical direction. Specifically, a plurality of cooling channels 72 are formed at substantially equal intervals along the circumferential direction of the cooling sleeve 7. As Figure 4 shown, in the present embodiment, eight cooling channels 72 are formed, but the number of cooling channels 72 is not particularly limited. In addition, in the present embodiment, in order to easily cool the plasma generation tube 3, the cooling channels 72 are provided in all the beam-shaped regions 71z, but they may also be provided in a part of the beam-shaped regions 71z.

[0053] In addition, the lower end portion of the cooling channel 72 is connected to a cooling fluid inlet P2 for allowing the cooling fluid to flow into the cooling channel 72, and the upper end portion of the cooling channel 72 is connected to a cooling fluid outlet P3 for allowing the cooling fluid to flow out of the cooling channel 72. That is, the direction in which the cooling fluid flows in the cooling channel 72 is opposite to the traveling direction of the gas flowing inside the plasma generation tube 3. In this way, inside the plasma generation tube 3, there is a tendency that the downstream side of the plasma generation tube 3 is more likely to be heated due to the plasma generation of the gas than the upstream side. Therefore, the cooling fluid at a low temperature flows in from the lower part of the cooling channel 72, which can improve the cooling efficiency of the plasma generation tube 3.

[0054] The heat transfer member 73 is provided between the inner circumferential surface of the beam-shaped region 71z and the outer circumferential surface of the plasma generation tube 3 and is in contact with them respectively. In the present embodiment, the heat transfer member 73 is formed from the upper end portion to the lower end portion of the cooling sleeve 7 along the vertical direction, but the heat transfer member 73 may also be provided on a part in the vertical direction. The material constituting the heat transfer member 73 is, for example, an ultra-low hardness heat dissipation silicone gasket.

[0055] The housing 8 is substantially cylindrical, and by housing the plasma generation tube 3 and the cooling sleeve 7, it cuts off the emission of microwaves to the outside. The housing 8 is configured to be divisible into a plurality of components. In the present embodiment, as Figure 5 shown, the housing 8 is configured to be divisible into two components, a first half body 81 and a second half body 82, which are respectively substantially semi-cylindrical, along the vertical direction. Specifically, as Figure 5 (a) shows, with the plasma generation tube 3 and the cooling sleeve 7 being clamped between the first half body 81 and the second half body 82, the first half body 81 and the second half body 82 are fixed, and the plasma generation tube 3 and the cooling sleeve 7 are housed in the housing 8. Moreover, as Figure 5As shown in (b), the housing 8 is removed by separating the first half 81 and the second half 82 in the vertical direction.

[0056] In addition, an opening 8a that opens toward the microwave generation source 2 and is connected to the waveguide 4 is formed on the first half 81. An opening 8b that opens toward the reflector 5 and is connected to the waveguide 4 is formed on the second half 82.

[0057] Moreover, an observation window W for observing the internal state of the plasma generation tube 3 is formed on the housing 8. Specifically, the observation window W is a through hole that penetrates from the outer circumferential surface to the inner circumferential surface of the housing 8. In the present embodiment, a plurality of observation windows W are formed in the vertical direction of the housing 8. More specifically, the plurality of observation windows W are formed from the upper part to the lower part of each of the first half 81 and the second half 82 at substantially equal intervals. In addition, the number and formation position of the observation windows W are not particularly limited.

[0058] Hereinafter, examples will be listed to more specifically illustrate the present invention. The present invention is not limited to the following examples, and the above and the following contents can be appropriately changed and implemented, and these are all included in the technical scope of the present invention.

[0059] <Example: Comparison of Resonance Frequencies> Next, with reference to Figure 6 the measurement results of comparing the resonance frequencies of the cooling sleeve and the housing having 3 slits with the resonance frequencies of the cooling sleeve and the housing having other numbers of slits will be described.

[0060] Here, the resonance frequencies of the cooling sleeve and the housing having 3 and 8 slits were measured with a network analyzer.

[0061] As a result, it was confirmed that in the cooling sleeve having 3 slits, the resonance frequencies of the cooling sleeve and the housing were 2.40 GHz. On the other hand, it was confirmed that in the cooling sleeve having 4 slits, the resonance frequencies of the cooling sleeve and the housing were around 2.76 GHz. In addition, it was confirmed that in the cooling sleeve having 8 slits, the resonance frequencies of the cooling sleeve and the housing were around 4.00 GHz. In addition, it is inferred that in the cooling sleeve having 1 or 2 slits, the resonance frequencies of the cooling sleeve and the housing are values smaller than the resonance frequency of 2.40 GHz in the case of the cooling sleeve having 3 slits. Therefore, compared with the cooling sleeve having other numbers of slits, the cooling sleeve having 3 slits has the smallest deviation between the resonance frequencies of the cooling sleeve and the housing and the microwave frequency of 2.45 GHz, so the burden of matching adjustment of the matcher can be reduced.

[0062] <Example: Comparison of Etching Rates> Next, in a plasma generation device equipped with a cooling jacket having 3 and 8 slits, while supplying a gas (etching gas) for etching a wafer to the plasma generation tube, microwave (frequency 2.45 GHz) was irradiated to the plasma generation tube to ionize the etching gas flowing in the plasma generation tube. In addition, the microwave was irradiated in such a way that the vibration direction of the electric field was perpendicular to the height direction (the length direction of the slit) of the plasma generation tube. Moreover, the wafer was etched using the ionized gas, and the etching rate was measured under the following 4 conditions.

[0063] Condition 1: The pressure of the etching gas was 100 Pa, the composition and concentration of the etching gas were 1400 sccm of SF6 and 400 sccm of O2, and the microwave output was 1000 W. Condition 2: The pressure of the etching gas was 200 Pa, the composition and concentration of the etching gas were 1400 sccm of SF6 and 400 sccm of O2, and the microwave output was 1000 W. Condition 3: The pressure of the etching gas was 100 Pa, the composition and concentration of the etching gas were 1400 sccm of SF6, and the microwave output was 1000 W. Condition 4: The pressure of the etching gas was 100 Pa, the composition and concentration of the etching gas were 1400 sccm of SF6 and 400 sccm of O2, and the microwave output was 500 W.

[0064] Figure 7 It is an etching rate diagram when etching the wafer under the above 4 conditions in a cooling jacket having 3 and 8 slits. In the case of Condition 1, the etching rate of the plasma generation device equipped with a cooling jacket having 3 slits was 330.1 nm / min, and the etching rate of the plasma generation device equipped with a cooling jacket having 8 slits was 385.5 nm / min. In the case of Condition 2, the etching rate of the plasma generation device equipped with a cooling jacket having 3 slits was 822.0 nm / min, and the etching rate of the plasma generation device equipped with a cooling jacket having 8 slits was 805.8 nm / min. In the case of Condition 3, the etching rate of the plasma generation device equipped with a cooling jacket having 3 slits was 617.0 nm / min, and the etching rate of the plasma generation device equipped with a cooling jacket having 8 slits was 570.0 nm / min. In the case of Condition 4, the etching rate of the plasma generation device equipped with a cooling jacket having 3 slits was 153.3 nm / min, and the etching rate of the plasma generation device equipped with a cooling jacket having 8 slits was 129.0 nm / min. Therefore, although it was thought that the etching rate would increase if the number of slits in the cooling sleeve increased, it was found that there was not much difference in the etching rate between 3 and 8 slits in any of Conditions 1 to 4. It was confirmed that plasma could be efficiently generated in the plasma generating device equipped with the cooling sleeve having 3 slits.

[0065] <Effects of the present embodiment> According to the plasma generating device 100 in the present embodiment, since the cooling sleeve 7 has 3 slits 71, the resonance frequency of the cooling sleeve 7 and the housing 8 is around 2.45 GHz. As a result, the deviation of the microwave frequency from this resonance frequency is smaller than that of the cooling sleeve having other numbers of slits. Therefore, the adjustment time for making the resonance impedance of the cooling sleeve 7 and the housing 8 match the impedance of the microwave generating source 2 can be shortened, and the burden during the matching adjustment of the matcher 6 can be reduced. In addition, since there is not much difference in the etching rate between 3 and 8 slits, plasma can also be efficiently generated in the plasma generating device equipped with the cooling sleeve having 3 slits.

[0066] In addition, since the slits 71 are formed along the direction perpendicular to the vibration direction of the electric field of the microwave, and the long side of the rectangle forming the cross-section of the waveguide 4 extends along the direction in which the slits 71 extend, the reflection of the microwave on the cooling sleeve 7 is suppressed, and the microwave can pass through the slits 71 efficiently. As a result, the microwave irradiates the plasma generating tube 3 appropriately, so that the gas flowing inside the plasma generating tube 3 can be efficiently ionized.

[0067] Moreover, since the two slits 71a and 71b face the microwave generating source 2, the microwave generated from the microwave generating source 2 can be transmitted to the plasma generating tube 3 more efficiently than in the case where only 1 slit faces the microwave generating source 2. As a result, the gas flowing inside the plasma generating tube 3 can be efficiently ionized. In addition, since 1 slit 71c faces the reflector 5, the gas flowing inside can be uniformly ionized in the circumferential direction of the plasma generating tube 3.

[0068] In addition, for example, the plasma generated inside the plasma generating tube 3 can be visually recognized through the observation window W, or for example, the temperature of the plasma generating tube 3 can be confirmed by inserting a thermometer such as a fiber optic thermometer into the observation window W. As a result, it is possible to prevent the microwave from being emitted to the outside and observe the internal state of the plasma generating tube 3.

[0069] Moreover, since the housing 8 is configured to be divisible into a plurality of components, the housing 8 can be easily loaded and unloaded.

[0070] Moreover, since the plasma generation tube 3 is made of yttrium oxide, by-products can be prevented from being generated when fluorine-containing gas is plasmaized.

[0071] <Other Embodiments> In addition, the present invention is not limited to the above-described embodiments.

[0072] In the above-described embodiment, the three slits 71 are formed from the upper end portion to the lower end portion of the cooling jacket 7 and are arranged along the circumferential direction of the cooling jacket 7. When the cooling jacket 7 and the housing 8 resonate near the frequency of the microwave generation source 2, as Figure 8 (b) to (d) show, one slit 71 can be divided into a plurality of slits.

[0073] For example Figure 8 (b) shows that one slit 71 has a long-side direction component along the vertical direction and can be divided into a plurality of slits 71 along the vertical direction. In addition, as Figure 8 (c) shows, one slit 71 has a long-side direction component inclined with respect to the vertical direction and can be divided into a plurality of slits 71 along the inclined long-side direction. Moreover, for example Figure 8 (d) shows that it can be divided into a plurality of slits 71 along a substantially imaginary straight line C inclined with respect to the vertical direction. In addition, Figure 8 (d) In the case of, the plurality of slits 71 have a long-side direction component along the vertical direction.

[0074] In the above-described embodiment, the three slits 71 are formed from the upper end portion to the lower end portion of the cooling jacket 7, but it is not limited thereto. For example, each slit 71 is formed on a part from the upper end portion to the lower end portion of the cooling jacket 7. When the cooling jacket 7 and the housing 8 resonate, in Figure 8 (a) shows that three slits 71 are formed.

[0075] At this time, for example Figure 8 (b) shows that the three slits 71 each have a long-side direction component along the vertical direction and are arranged on a substantially straight line parallel to the long-side direction component of the slit 71. In addition, for example Figure 8 (c) shows that the three slits 71 each have a long-side direction component inclined with respect to the vertical direction and are arranged on a substantially straight line parallel to the long-side direction component of the slit 71. Moreover, for example Figure 8 (d) shows that the three slits 71 each have a long-side direction component along the vertical direction and are arranged on a substantially imaginary line C inclined with respect to the vertical direction.

[0076] In the above-described embodiment, the slit 71 is formed such that its long-side direction is perpendicular to the vibration direction of the electric field of the microwave. However, it suffices that the long-side direction of the slit 71 includes the up-and-down direction in its long-side direction component. That is, the long-side direction of the slit 71 may be inclined with respect to the direction perpendicular to the vibration direction of the electric field of the microwave.

[0077] In the above-described embodiment, the two slits 71a and 71b face the microwave generation source 2. However, the orientation of each slit 71 is not limited thereto. For example, all three slits 71 may face the microwave generation source 2, or only one slit 71 may face the microwave generation source 2.

[0078] In the above-described embodiment, the plasma generation device 100 includes the reflector 5, but the reflector 5 may be absent.

[0079] In the above-described embodiment, the observation window W is formed in the housing 8, but the observation window W may be absent from the housing 8.

[0080] In the above-described embodiment, the housing 8 can be divided into two members, the first half 81 and the second half 82, but it may also be divided into three or more members, or may be formed integrally. In addition, the housing 8 can be divided along the up-and-down direction, but the direction in which the housing 8 can be divided is not limited to the up-and-down direction. For example, it may be a direction perpendicular to the up-and-down direction or other directions.

[0081] Moreover, as Figure 9 and Figure 10 shown, the plasma generation device 100 may include a plurality of plasma detection units 9 for detecting the light emission intensity of the plasma generated inside the plasma generation tube 3. Here, the plurality of plasma detection units 9 are arranged opposite to the direction in which the slit 71 opens. More specifically, the plurality of plasma detection units 9 are provided on the outer circumferential surface of the housing 8 by means of a mounting member B having a long-side component in the up-and-down direction.

[0082] The plasma detection unit 9 detects the light emission intensity of the plasma in a specified region inside the plasma generation tube 3 through the slit 71. Here, the plasma detection unit 9 is, for example, a photodiode or the like, and outputs an analog signal corresponding to the light emission intensity of the plasma to a calculation device (not shown). In addition, the plasma detection unit 9 may include a filter for detecting the light emission intensity of the plasma in a specified wavelength.

[0083] The calculation device is a computer having a CPU, an internal memory, an input / output interface, etc., and can perform A / D conversion on the analog signal obtained from the plasma detection unit 9. In addition, the calculation device can display the distribution state of the plasma in real time on a display unit (not shown) such as a monitor, for example.

[0084] Here, as Figure 9As shown, a plurality of plasma detection units 9 are arranged along the vertical direction of the plasma generation tube 3, that is, along the traveling direction of the gas. Here, as Figure 9 and Figure 10 shown, a plurality of plasma detection units 9 are arranged along the direction in which a single slit 71 opening toward the microwave generation source 2 extends. In addition, in order to detect the distribution state of the plasma in the direction intersecting the traveling direction of the gas, a plurality of plasma detection units 9 may be respectively arranged opposite to two slits 71 opening toward the microwave generation source 2.

[0085] The plurality of plasma detection units 9 detect the luminescence intensity of the plasma in different regions inside the plasma generation tube 3. Specifically, as Figure 9 shown, three plasma detection units 9 respectively detect the luminescence intensity of the plasma in the upper part, the central part, and the lower part of the plasma generation tube 3 in the traveling direction of the gas. In addition, in order to more accurately detect the distribution state of the plasma, it is sufficient that at least one plasma detection unit 9 detects the luminescence intensity of the plasma in the central part of the plasma generation tube 3. In addition, the number of plasma detection units 9 is not limited to three, as long as it is at least two or more.

[0086] In addition, within the scope not departing from the idea of the present invention, various modifications and combinations of embodiments can be implemented.

[0087] According to the present invention, in a plasma generation device that plasmaizes a gas using microwaves, the matcher can be operated quickly, reducing the burden on the matcher.

[0088] Description of Reference Numerals 100 Plasma generation device 2 Microwave generation source 3 Plasma generation tube 4 Waveguide 5 Reflector 6 Matcher 7 Cooling jacket 71 Slit 71z Beam-shaped region 72 Cooling channel 73 Heat transfer member 8 Housing 81 First half body 82 Second half body 9 Plasma detection unit W Observation window.

Claims

1. A plasma generating device, characterized in that, Comprising: A microwave generation source for generating microwaves; A plasma generation tube, which is cylindrical, and the gas ionized by the microwaves flows inside; A waveguide for transmitting the microwaves generated from the microwave generation source to the plasma generation tube; A matcher disposed in the waveguide between the microwave generation source and the plasma generation tube; A cooling sleeve disposed on the outer circumferential surface of the plasma generation tube for cooling the plasma generation tube; and A housing, which is cylindrical and houses the plasma generation tube and the cooling sleeve, The cooling sleeve has: Three slits extending along the traveling direction of the gas flowing in the plasma generation tube or extending obliquely with respect to the traveling direction, allowing the microwaves to pass through to the plasma generation tube; and Cooling channels disposed between the adjacent slits, and the cooling fluid for cooling the plasma generation tube flows in the cooling channels.

2. The plasma generation device according to claim 1, wherein The slits extend along a direction perpendicular to the vibration direction of the electric field of the microwaves or extend obliquely with respect to the perpendicular direction, The cross-section of the waveguide is rectangular, and the long side forming the rectangle extends along the direction in which the slits extend or extends obliquely with respect to the extending direction.

3. The plasma generating device according to claim 1 or 2, characterized in that, At least two of the three slits face the microwave generation source.

4. The plasma generation device according to claim 1 or 2, wherein It further includes a reflector disposed in the waveguide opposite to the microwave generation source with the plasma generation tube therebetween, and reflecting the microwaves from the microwave generation source towards the plasma generation tube, At least one of the three slits is formed facing the reflector, and at least one of the other slits is formed facing the microwave generation source.

5. The plasma generating device according to any one of claims 1 to 4, characterized in that, The housing is formed with an observation window for observing the internal state of the plasma generation tube.

6. The plasma generating device according to claim 5, wherein, The housing is configured to be divisible into multiple components.

7. The plasma generating device according to any one of claims 1 to 6, characterized in that, The plasma generation tube is composed of yttrium oxide, quartz coated with yttrium oxide, and / or sapphire tube, or a combination thereof.

8. The plasma generating device according to any one of claims 1 to 7, characterized in that, It further includes a plurality of plasma detection parts, which are arranged opposite to the direction of the slit openings, and detect the light emission intensity of the plasma generated inside the plasma generation tube.

9. The plasma generating device according to claim 8, wherein The plurality of plasma detection parts are arranged along the traveling direction of the gas.

10. The plasma generating device according to claim 9, characterized in that, The plurality of plasma detection parts respectively detect the light emission intensity of the plasma in the upper part, the central part, and the lower part of the plasma generation tube in the traveling direction of the gas.

11. A cooling sleeve disposed on the outer circumferential surface of a plasma generation tube, the plasma generation tube being cylindrical and the gas ionized by microwaves flowing inside, the cooling sleeve being used to cool the plasma generation tube, and the cooling sleeve is characterized by including: Three slits extending along the traveling direction of the gas flowing in the plasma generation tube or extending obliquely with respect to the traveling direction, allowing the microwaves to pass through to the plasma generation tube; and A cooling channel is formed between the adjacent slits, and a cooling fluid for cooling the plasma generation tube flows in the cooling channel.

12. A cooling sleeve is disposed on the outer circumferential surface of a plasma generating tube. The plasma generating tube is cylindrical, and a gas that is plasma - generated by microwaves flows inside. The cooling sleeve is used to cool the plasma generating tube, and the cooling sleeve is characterized in that, Comprising: Slits extending along a direction perpendicular to the vibration direction of the electric field of the microwave or extending obliquely with respect to the perpendicular direction, allowing the microwave to pass through to the plasma generation tube; and A cooling channel is separately provided from the slits, and a cooling fluid for cooling the plasma generation tube flows in the cooling channel. The cross-section of the waveguide is rectangular, and the long side forming the rectangle extends along the direction in which the slit extends or is inclined with respect to the extending direction.

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