Plasma treatment device

Abstract

In order to solve not only the problem of in-plane uniformity of etching processing but also the problem of reducing charging damage and perform plasma density distribution control with a high degree of freedom, a plasma processing device is provided with a plasma processing chamber for performing plasma processing on a substrate, and is provided with: a vacuum cavity capable of exhausting the interior of the plasma processing chamber into a vacuum; and a microwave power supply unit having a microwave source and a circular waveguide and supplying microwave power oscillating from the microwave source to the vacuum cavity via the circular waveguide. In the plasma processing device, the microwave power supply unit is composed of a plurality of waveguides arranged between the circular waveguide and the vacuum cavity, which are coaxially arranged with the circular waveguide and have different dielectric constants inside.

Description

Technical Field

[0001] The present invention relates to a plasma processing device using microwaves. Background Art

[0002] The development of etching processing technology with high aspect ratio is being promoted by the high integration of semiconductor devices. One of the micro-etching technologies in the semiconductor field is dry etching technology, and dry etching processing using plasma is particularly commonly used.

[0003] Plasma uses collisions with electrons and molecules or atoms of the process gas to excite the molecules or atoms of the process gas, generating ions and free radicals. The plasma processing device achieves anisotropic etching with ions and isotropic etching with free radicals. As a plasma source, there is electron cyclotron resonance (ECR).

[0004] As the structure of an existing ECR etching device, the following structure is described in Patent Document 1: 2.45 GHz microwaves emitted from a magnetron are propagated in a rectangular waveguide and a circular waveguide, and are introduced into a processing chamber where a magnetic field is being formed through a quartz window located at the top of the processing chamber. Electron cyclotron resonance is induced by an electric field based on the microwave and a magnetic field formed in a direction perpendicular to the microwave, thereby generating a high-density plasma to process the substrate.

[0005] In addition, Patent Document 2 describes a microwave-based discharge generating device, which is configured as follows: a dielectric is filled between the inner wall of a cavity resonator and a discharge tube, and when gas conditions or a substrate are changed, the dielectric is replaced with a dielectric with a different dielectric constant so that the resonance frequency of the cavity resonator and the microwave oscillation frequency of a magnetron are consistent, and when a liquid dielectric is used, it is introduced from outside the cavity resonator, flows through the inner wall of the cavity resonator and the discharge tube, and is discharged to the outside of the cavity resonator.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 6-77147

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 7-57894

[0010] Non-patent literature

[0011] Non-patent document 1: WAVEGUIDE HANDBOOK N.MARCUVITZ Summary of the invention

[0012] Problems to be solved by the invention

[0013] It is generally known that the plasma density on the wall of the processing chamber of a plasma processing device is lower than that in the center of the processing chamber due to the loss caused by the reaction on the wall, that is, the solid surface. Due to such uneven distribution of plasma density, the etching rate on the processed substrate becomes uneven.

[0014] Patent Document 1 adopts a structure in which microwave power introduced into the processing chamber is divided using inner and outer waveguides to improve the non-uniformity of plasma density distribution in the processing chamber. With such a structure, the plasma density on the wall surface of the processing chamber can be increased.

[0015] However, in the structure disclosed in Patent Document 1, since a single microwave source is used, the microwave power ratio between the center of the processing chamber and the wall side is fixed due to the number of waveguides arranged. On the other hand, when plasma processing is performed, the hardware of the processing device may be changed according to the process conditions, and the microwave power ratio needs to be adjusted accordingly. However, in the structure disclosed in Patent Document 1, it is difficult to flexibly cope with the adjustment of the power ratio.

[0016] Furthermore, in the manufacturing process of semiconductor devices, the etching rate of the substrate being processed does not necessarily depend on the plasma density. Therefore, for example, when a process condition such as heat distribution is prioritized, in order to obtain uniformity of processing, if the plasma density can be adjusted in the order of high peripheral, high center, and uniform in one process cycle, uniformity of the etching surface on the substrate being processed can be finally obtained.

[0017] In addition, when etching a thin film of a semiconductor element, the distribution of the thin film on the substrate to be processed often results in a non-uniform film thickness due to the exhaust conductivity of the film forming device, the symmetry of the processing chamber, and other characteristics. For example, in the case where the film thickness distribution of the thin film to be etched is a convex distribution such as high at the center and low at the periphery, it is desirable to control the input power of microwaves at the center of the substrate to be processed to be larger than the input power at the periphery. On the other hand, in the case where the film thickness is a concave distribution such as low at the center and high at the periphery, it is necessary to make the input power of microwaves at the center of the substrate to be processed smaller than the input power at the periphery.

[0018] As described above, since there are various factors for achieving in-plane uniformity in etching processing, plasma density distribution control with a high degree of freedom is required for an etching apparatus using plasma.

[0019] On the other hand, in order to realize anisotropic etching using ion injection, a structure is adopted in which bias power is applied to the substrate electrode using an RF power supply. If RF bias power is applied to the substrate electrode in a state where plasma is generated in the processing chamber, charges are accumulated on the surface of the substrate placed on the substrate electrode, and there is a possibility that the semiconductor element formed on the substrate will be damaged by charging. Reducing the generation of this charging damage can greatly contribute to improving the yield of semiconductor elements.

[0020] Therefore, a plasma etching apparatus having a high degree of freedom in controlling the plasma density distribution is desired in order to solve not only the problem of improving the in-plane uniformity of etching processing but also the problem of reducing charging damage.

[0021] On the other hand, in the microwave discharge generating device described in Patent Document 2, the space between the inner wall of the cavity resonator and the discharge tube is filled with a dielectric, and control of the distribution of plasma density inside the discharge tube on which the substrate is mounted is not considered.

[0022] The present invention solves the above-mentioned problems and provides a plasma processing apparatus capable of performing plasma density distribution control with a high degree of freedom in order to solve not only the problem of in-plane uniformity of etching processing but also the problem of reducing charging damage.

[0023] Means for solving problems

[0024] In order to solve the above-mentioned problems, the present invention is characterized in that a plasma processing device comprises: a processing chamber for performing plasma processing on a sample; a high-frequency power supply for providing high-frequency power of microwaves for generating plasma via a waveguide; and a magnetic field forming mechanism for forming a magnetic field inside the processing chamber, the waveguide comprising: a first circular waveguide tube filled with a liquid dielectric; and a second circular waveguide tube arranged outside the first circular waveguide tube and arranged coaxially with the first circular waveguide tube.

[0025] In addition, in order to solve the above-mentioned problems, the present invention is constructed as follows: a microwave power control system controls the microwave power of a plasma processing device, wherein the plasma processing device includes: a processing chamber for performing plasma processing on a sample; a high-frequency power supply for providing high-frequency power of microwaves for generating plasma via a waveguide; and a magnetic field forming mechanism for forming a magnetic field inside the processing chamber, the waveguide includes: a first circular waveguide tube of a dielectric filled with a liquid; a second circular waveguide tube arranged on the outside of the first circular waveguide tube and arranged coaxially with the first circular waveguide tube, and the ratio of the microwave power propagating in the first circular waveguide tube to the microwave power propagating in the second circular waveguide tube is controlled by controlling the liquid level of the dielectric.

[0026] Effects of the Invention

[0027] According to the present invention, the plasma density in the plasma processing apparatus can be controlled in accordance with a desired etching rate, and the problem of not only improving the in-plane uniformity of plasma processing but also reducing charging damage can be solved with a relatively high degree of freedom. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a longitudinal sectional view schematically showing the structure of the main part of the plasma processing apparatus according to the embodiment of the present invention.

[0029] Figure 2 It is a longitudinal sectional view showing the structure of a waveguide for adjusting microwave power in a plasma processing apparatus according to an embodiment of the present invention.

[0030] Figure 3 This is a graph showing the results of obtaining, by simulation, the relationship between the dielectric liquid level and the microwave split power ratio in the plasma processing apparatus according to the embodiment of the present invention.

[0031] Figure 4 This is a flowchart showing the flow of a process for calculating a pump operation time for adjusting a liquid level according to an embodiment of the present invention.

[0032] Figure 5 This is a graph showing the relationship between the liquid surface level and the average value in one sampling cycle or a plurality of sampling cycles of the liquid level sensor according to the embodiment of the present invention.

[0033] Figure 6 This is a graph showing the relationship between the liquid surface level and the injection amount of the liquid dielectric into the inner waveguide according to the embodiment of the present invention.

[0034] Figure 7 This is a graph showing the relationship between the injection amount of the liquid dielectric into the inner waveguide and the pump operation time according to the embodiment of the present invention. DETAILED DESCRIPTION

[0035] The present invention relates to a plasma processing device (ECR plasma etching device), which can specifically control the distribution of microwave radiation power into a plasma processing chamber based on the relative dielectric constant and filling amount of the liquid dielectric filled in the inner waveguide and the outer waveguide with a hollow interior that are coaxially arranged.

[0036] In addition, in the present invention, the microwave power from a single microwave source is divided into a coaxially arranged inner waveguide and an outer waveguide, respectively, and the microwave power passing through the inner waveguide is increased or decreased according to the filling amount of the liquid dielectric located inside the inner waveguide. Thus, the microwave power division ratio between the inner waveguide and the outer waveguide can be adjusted, thereby controlling the plasma density in the plasma processing chamber in accordance with the desired etching rate.

[0037] In the ECR plasma etching device, the microwave power from the rectangular waveguide connected to the magnetron is branched into the coaxially arranged inner waveguide and outer waveguide, and the ends of the inner waveguide and the outer waveguide are connected to the inner radiation part and the outer radiation part arranged on the upper surface of each processing chamber, thereby radiating the microwave power into the interior of the plasma processing chamber by each radiation part.

[0038] Here, when limiting the propagation of microwave power in the inner waveguide, if the radius a of the inner waveguide is designed according to the formula (Formula 1), the microwave power can be passed or blocked.

[0039] [Mathematical formula 1]

[0040]

[0041] Here, fc is the microwave frequency 2.45 GHz, and C is the speed of light in vacuum 2.99x10 8 m / s.

[0042] For example, in the propagation of microwave power in TE11 mode, when the medium is air or vacuum, the value of its relative dielectric constant εr is 1, so according to the formula (Mathematical formula 1), the radius of the inner waveguide is 0.0357m. When the value of the relative dielectric constant εr of the medium in the inner waveguide is 2, the propagation speed of microwave power is as slow as 1 / Therefore, according to the formula (Formula 1), the radius of the inner waveguide becomes 0.0252m.

[0043] If the radius a of the inner waveguide is designed to be smaller than 0.0357 m and larger than 0.0252 m, then when the medium is vacuum or air, the 2.45 GHz microwave power is blocked, and thus the microwave power cannot pass through the waveguide having a certain length. That is, it is known that no microwave power is radiated from the inner radiation portion connected to the inner waveguide, and the plasma density near the center of the plasma processing chamber is reduced.

[0044] On the other hand, if a medium having a relative dielectric constant εr of 2 is inserted into the inner waveguide having the aforementioned radius a, microwave power can pass through the inner waveguide. That is, microwave power is radiated from the inner radiation portion connected to the inner waveguide, and the plasma density near the center of the plasma processing chamber increases. Therefore, the split power ratio of the microwave introduced into the processing chamber can be freely controlled according to the conditions of the etching process of the semiconductor element.

[0045] When the medium having a relative dielectric constant εr of 2 is used, for example, in the case of a liquid dielectric, since it is a liquid, its liquid level can be freely manipulated, thereby adjusting the power of the microwave passing through the inner waveguide. Therefore, regarding the split power ratio of the microwave power of the inner waveguide and the outer waveguide, the split power ratio can be adjusted within a certain range by the liquid level of the liquid dielectric. The definition of the split power ratio of the microwave is shown in the following formula (Mathematical Formula 2).

[0046] [Mathematical formula 2]

[0047]

[0048] Here, S 21 is the transmission S parameter of the inner waveguide, S 31 is the transmission S parameter of the outer waveguide.

[0049] The outer waveguide is coaxial with the inner waveguide and thus propagates microwaves as a coaxial waveguide. Although the coaxial waveguide has no shielding in the fundamental mode, TEM mode, the outer waveguide diameter b when shielding the higher-order mode TE11 can be determined using the following formula (Formula 3).

[0050] [Mathematical formula 3]

[0051]

[0052] Here a: Radius of the inner waveguide [m]

[0053] b: Radius of the outer waveguide [m]

[0054] Considering the formula (Math. 2), the outer waveguide is set to a size that does not serve as a shield.

[0055] The present invention is based on the above-described concept, and specific embodiments thereof will be described using the drawings.

[0056] The embodiments of the present invention will be described in detail below based on the drawings. In all the drawings for describing the present embodiments, the same reference numerals are given to elements having the same functions, and in principle, their repeated descriptions are omitted.

[0057] The present invention is not limited to the following embodiments, and the specific structure can be changed within the scope of the concept or gist of the present invention, which is easily understood by those skilled in the art.

[0058] Example

[0059] exist Figure 1 A schematic structure of a plasma processing apparatus (ECR plasma etching apparatus) 100 according to an embodiment of the present invention is shown.

[0060] exist Figure 1 In the structure shown, 101 is an oscillator of microwave power, 102 is an isolator, 103 is an automatic matcher, 111 is a rectangular waveguide, 112 is a circular-rectangular converter, 104 is a circular polarization generator, 113 is a circular waveguide, 114 is an outer waveguide, 115 is an inner waveguide, 116 is a liquid dielectric accommodated inside the inner waveguide 115, 117 is an inner cavity portion, and 118 is an outer cavity portion.

[0061] In addition, 120 is a plasma processing chamber, 121 is a vacuum chamber, 122 is an upper portion of the vacuum chamber, 123 is an inner cavity wall, 124 is a ring stay, 125 is a quartz window, 126 is a lower electrode, 127 is an RF power supply, 131 is an electromagnetic coil, 132 is a magnetic yoke, and 10 is a processed substrate.

[0062] In addition, Figure 1 In the structure shown, an exhaust unit for exhausting the interior of the vacuum chamber 121, i.e., the plasma processing chamber 120, into a vacuum, a gas supply unit for supplying a processing gas to the interior of the vacuum chamber 121, i.e., the plasma processing chamber 120, an oscillator 101 for controlling microwave power, an automatic matcher 103, an electromagnetic coil 131, an RF power supply 127, and other control units are omitted from the illustration.

[0063] In the above structure, microwave power of a frequency of 2.45 GHz outputted from a microwave oscillator 101 is transmitted to a circular-rectangular converter 112 by a rectangular waveguide 111 via an isolator 102 and an automatic matching device 103. A magnetron is used as the microwave oscillator 101. The circular-rectangular converter 112 also serves as a corner that bends the traveling direction of the microwave power by 90 degrees, thereby miniaturizing the entire device.

[0064] The circular polarization generator 104 is connected to the lower part of the circular-rectangular converter 112 to convert the microwave power incident with linear polarization into circular polarization. Furthermore, on the plasma processing chamber 120 side of the circular polarization generator 104, there is a circular waveguide 113 provided on the approximate central axis of the vacuum chamber 121 constituting the plasma processing chamber 120 to propagate the circularly polarized microwave power.

[0065] In this embodiment, the microwave power propagating from the circular waveguide 113 is incident on the outer waveguide 114 installed on the upper portion 122 of the vacuum chamber and the inner waveguide 115 arranged inside the outer waveguide 114 .

[0066] Here, the radius of the inner waveguide 115 is smaller than the radius of 0.0357 m that blocks microwave power when the interior is air as described using equation (1), and larger than the radius of 0.0252 m that blocks microwave power when the interior is filled with a liquid dielectric with a relative dielectric constant εr of 2.

[0067] Thus, when the liquid dielectric 116 is not contained and the interior is filled with air, the inner waveguide 115 blocks the microwave power. In this case, the microwave power propagated from the circular waveguide 113 enters only the outer waveguide 114.

[0068] On the other hand, when the liquid dielectric 116 is accommodated inside the inner waveguide 115 and the interior is filled with the liquid dielectric 116 , since the inner waveguide 115 propagates microwave power, the microwave power propagated from the circular waveguide 113 is incident on the outer waveguide 114 and the inner waveguide 115 .

[0069] The outer waveguide 114 is connected to the outer cavity 118 inside the upper part 122 of the vacuum chamber, and the inner waveguide 115 is connected to the inner cavity 117 divided by the inner cavity wall 123 inside the upper part 122 of the vacuum chamber. The outer cavity 118 and the inner cavity 117 are separated from the plasma processing chamber 120 inside the vacuum chamber 121 by the quartz window 125.

[0070] In order to perform ECR plasma etching, the outer periphery of the vacuum chamber 121 and the upper portion 122 of the vacuum chamber is covered with an electromagnetic coil 131 for forming a magnetic field inside the vacuum chamber 121 and the upper portion 122 of the vacuum chamber. A lower electrode 126 for placing the substrate 10 to be processed is provided at the central bottom surface of the plasma processing chamber 120.

[0071] An RF power supply 127 for applying RF bias power is connected to the lower electrode 126. By applying RF bias power from the RF power supply 127 to the lower electrode 126, ions of the processing gas ionized in the plasma are accelerated toward the substrate 10 carried on the lower electrode 126, and the thin film on the substrate 10 is removed.

[0072] The microwave power output from the oscillator 101 and propagating through the isolator 102 , the automatic matching device 103 , the circular-rectangular converter 112 , the circular polarization generator 104 , and the circular waveguide 113 is divided into the inner waveguide 115 and the outer waveguide 114 .

[0073] When the inner waveguide 115 is not filled with the liquid dielectric 116 , it is filled with air. In this state, as described above, the dielectric constant of air is 1, and the radius of the inner waveguide is formed to a size that blocks microwaves, so microwave power cannot pass through the inner waveguide 115 .

[0074] On the other hand, when the liquid dielectric 116 is filled into the inner waveguide 115, microwaves begin to leak from the inner waveguide 115. When the liquid dielectric 116 is gradually injected, the liquid level (liquid level) of the liquid dielectric 116 in the inner waveguide 115 becomes higher, and the amount of microwave power passing through also increases. By adjusting the liquid level of the liquid dielectric 116 in the inner waveguide 115, the ratio of the microwave power propagated from the circular waveguide 113 to the inner waveguide 115 and the microwave power propagated to the outer waveguide 114 can be changed.

[0075] exist Figure 2 The detailed structures of the inner waveguide 115 and the outer waveguide 114 are shown. The inner waveguide 115 has a hollow interior, and is provided with an upper cover 1151 and a bottom plate 1152 made of a dielectric material, thereby forming a sealed structure.

[0076] A quartz ring seat 124 is provided between the inner waveguide 115 and the outer waveguide 114, and the inner waveguide 115 and the outer waveguide 114 are coaxially fixed by the ring seat 124. In addition, in order to supply or discharge the liquid dielectric 116 to the inside of the inner waveguide 115 from the outside, a flow path 141 is formed from the outer waveguide 114 through the ring seat 124 and reaches the inner waveguide 115.

[0077] The flow path 141 is connected to a pump 243 for supplying or discharging the liquid dielectric 116 to or from the inner waveguide 115. The pump 243 is controlled by the control unit 242 to supply the liquid dielectric 116 stored in the storage unit 244 to the inner waveguide 115 through the flow path 141. In addition, the liquid dielectric 116 in the inner waveguide 115 is discharged to one side of the storage unit 244 through the flow path 141.

[0078] In order to monitor the liquid level of the liquid dielectric 116 in the inner waveguide 115, a connecting pipe 142 is provided from the outer waveguide 114 through the ring seat 124 to the inner waveguide 115. The connecting pipe 142 is connected to the liquid level sensor 241 through a pipe 245.

[0079] Next, a series of actions of the liquid level control system for filling / discharging the liquid dielectric 116 inside the inner waveguide 115 will be described. The liquid level of the liquid dielectric 116 inside the inner waveguide 115 is measured by using a liquid level sensor 241 via a pipe 245 connected to the connecting pipe 142, and the liquid level is fed back to the control unit 242 as an electronic signal.

[0080] When the liquid dielectric 116 is filled into the inner waveguide 115, the liquid dielectric 116 is sucked up from the storage portion 244 for storing the liquid dielectric 116 by the pump 243, and the liquid dielectric 116 is filled into the inner waveguide 115. If the pump 243 is rotated in the reverse direction, the liquid dielectric 116 in the inner waveguide 115 is sucked out and returned to the storage portion 244 for storing the liquid dielectric 116.

[0081] The control unit 242 has a program for adjusting the liquid level of the liquid dielectric 116 inside the inner waveguide 115 based on the liquid level detection signal from the liquid level sensor 241 so that the ratio of the microwave power propagated from the circular waveguide 113 to the inner waveguide 115 and the microwave power propagated to the outer waveguide 114 (microwave split power ratio) becomes a preset value. The operation time of the pump 243 is controlled by the program so that the desired microwave split power ratio is achieved.

[0082] exist Figure 3 The results of obtaining the relationship between the split power ratio and the dielectric liquid level through electromagnetic field simulation are shown. Figure 3 In the graph 300 shown, the vertical axis shows the microwave power division ratio, and the horizontal axis shows the level of the liquid surface of the dielectric liquid as the dielectric liquid level.

[0083] As can be seen from the graph, the liquid dielectric level and the split power ratio are roughly in a linear relationship as shown by the straight line 310. Therefore, if a program for converting the linear relationship into a polynomial is installed in the control unit 242, the setting value of the liquid dielectric level required to obtain the desired microwave split power ratio can be converted from the desired microwave split power ratio.

[0084] Next, refer to Figures 5 to 7 ,use Figure 4 The flow of a process for determining the operation time of the pump 243 based on a desired microwave split power ratio between the inner waveguide 115 and the outer waveguide 114 will be described.

[0085] First, the desired split power ratio of the microwave power is input (S401). Figure 3 The value of the liquid level (liquid level) of the liquid dielectric corresponding to the input desired microwave division power ratio is obtained from the graph shown in the figure, and is set as a set value (S402).

[0086] Next, the level (liquid level) of the liquid dielectric 116 inside the inner waveguide tube 115 is detected by the liquid level sensor 241 (S403), and the liquid level of the liquid dielectric 116 corresponding to the detection signal of the liquid level sensor 241 is obtained based on the relationship between the detection signal of the liquid level sensor 241 and the level of the liquid surface of the liquid dielectric 116 inside the inner waveguide tube 115 obtained in advance (S404).

[0087] Next, if Figure 5 As shown in the graph 500 of , the difference (liquid surface level difference 511) between the obtained value of the liquid level of the liquid dielectric 116 inside the inner waveguide 115 (sensor liquid level 53) and the set value (set dielectric liquid level 52) obtained in S402 is calculated (S405).

[0088] Next, based on the pre-obtained Figure 6 The required injection amount 612 (S406) of the liquid dielectric 116 injected into the inner waveguide 115 is calculated based on the relationship 610 between the injection amount of the liquid dielectric 116 supplied from the pump 243 to the inner waveguide 115 and the liquid level 610 of the liquid dielectric 116 inside the inner waveguide 115 detected by the liquid level sensor 241.

[0089] Finally, based on Figure 7 The pump operation time (S407) is calculated based on the relationship 710 to 730 between the pump operation time (PT) of the pump 243 with the temperature of the liquid dielectric 116 as a parameter and the injection amount into the inner waveguide 115, which is pre-obtained as shown in the graph 700, to calculate the pump operation time (PT) of the pump 243 (S407).

[0090] Based on the pump operation time thus obtained, the control unit 242 controls the pump 243 to supply the liquid dielectric 116 to the inside of the inner waveguide 115. Thus, the microwave power oscillated from the oscillator 101 and propagated from the circular waveguide 113 is split and propagated to the inner waveguide 115 and the outer waveguide 114 according to the desired microwave split power ratio.

[0091] By controlling the liquid surface level of the liquid dielectric 116 inside the inner waveguide 115 based on the processing flow described above, even if the volume of the liquid dielectric 116 changes depending on the temperature, a desired microwave power division ratio can be adjusted.

[0092] Next, a process of processing the substrate 10 in this embodiment will be described.

[0093] First, the pump 243 is controlled by the control unit 242 so that the pump operation time obtained by the above-described process is achieved, and the liquid dielectric 116 is supplied to the inner waveguide 115. Next, in this state, the plasma processing chamber 120 is evacuated to a vacuum by an exhaust unit (not shown), and a processing gas is supplied to the plasma processing chamber 120 from a gas supply unit (not shown), and settings are made so that the plasma processing chamber 120 becomes a given pressure.

[0094] In this state, the oscillator 101 is driven to transmit microwave power. The microwave power transmitted from the oscillator 101 propagates through the isolator 102, the automatic matching device 103, the circular-rectangular converter 112, the circular polarization generator 104, and the circular waveguide 113, and is divided and input to the inner waveguide 115 and the outer waveguide 114.

[0095] Here, regarding the inner waveguide 115 and the outer waveguide 114, since the liquid level of the liquid dielectric 116 inside the inner waveguide 115 is adjusted so as to achieve a desired microwave power division ratio, the microwave power divided at the desired division ratio is propagated from the inner waveguide 115 to the inner cavity portion 117 and from the outer waveguide 114 to the outer cavity portion 118.

[0096] The microwave power thus divided and propagated inside the inner waveguide 115 propagates from the inner cavity 117 connected to the inner waveguide 115 to the vicinity of the center of the plasma processing chamber 120 through the quartz window 125. On the other hand, the microwave power divided and propagated inside the outer waveguide 114 propagates from the outer cavity 118 connected to the outer waveguide 114 to the vicinity of the peripheral portion (the portion away from the center) of the plasma processing chamber 120 through the quartz window 125.

[0097] In the plasma processing chamber 120, plasma having a density corresponding to the microwave power propagated from the inner cavity portion 117 is generated near the center portion of the plasma processing chamber 120, and plasma having a density corresponding to the microwave power propagated from the outer cavity portion 118 is generated in a portion away from the center portion of the plasma processing chamber 120, thereby generating plasma having a desired density distribution for the plasma processing chamber 120 as a whole.

[0098] By causing the plasma processing chamber 120 to generate plasma having a desired plasma density distribution, when etching the substrate 10 placed on the lower electrode 126 , etching can be performed with uniformity in the surface of the etching process and with reduced charging damage.

[0099] According to this embodiment, by providing a structure capable of adjusting the microwave power division ratio propagating to the inner waveguide 115 and the outer waveguide 114, even if the structure of the etching device is changed in accordance with the process conditions, and even if the film thickness distribution of the thin film formed on the processed substrate is uneven, the plasma density in the plasma processing device can be controlled in accordance with the desired etching rate, thereby maintaining the in-plane uniformity of the etching process while performing etching processing that reduces charging damage.

[0100] In addition, when the present embodiment is applied to a plasma etching device with a 12-inch substrate to be processed, the relative dielectric constant εr of the liquid dielectric is expected to be about 2 in the current situation, depending on the size of the waveguide tube of the microwave power. For example, there are silicone oil, Fluorinert (trademark) manufactured by 3M, and Galden (trademark) manufactured by Solvay. Since the size of the waveguide tube is changed accordingly to the large-scale processing device corresponding to the large-scale substrate to be processed, the value of the relative dielectric constant εr of the liquid dielectric is not particularly restricted as long as the function of the present invention of shielding or passing microwaves according to the presence or absence of the liquid dielectric is realized.

[0101] Furthermore, the upper cover 1151 and the bottom plate 1152 of the inner waveguide 115 in this embodiment are preferably in the shape of a disk or a cone, but any shape is acceptable as long as the liquid dielectric 116 can be sealed inside the inner waveguide 115 and the reflected power of the microwave can be reduced. In order to allow microwaves to pass through, a dielectric such as quartz or ceramic is preferred in the upper cover 1151 and the bottom plate 1152. In order to reduce the reflection of microwave power, the ring seat 124 for connecting the inner waveguide 115 and the outer waveguide 114 is preferably made of a dielectric such as quartz or ceramic.

[0102] The invention made by the inventor is specifically described above based on the embodiments, but the present invention is not limited to the embodiments, and various changes can be made within the scope of the gist. For example, the above embodiments are described in detail to explain the present invention in an easy-to-understand manner, but are not necessarily limited to all the structures described.

[0103] Description of Reference Numerals

[0104] 10. Processed substrate

[0105] 101 Oscillator

[0106] 102 Isolator

[0107] 103 Automatic Matcher

[0108] 104 Circular Polarization Generator

[0109] 113 Circular waveguide

[0110] 114 Outer waveguide

[0111] 115 Inner waveguide

[0112] 116 Liquid Dielectric

[0113] 117 Inner cavity

[0114] 118 outer cavity

[0115] 120 Plasma treatment chamber

[0116] 121 Vacuum chamber

[0117] 122 Vacuum chamber upper part

[0118] 123 Inner cavity wall

[0119] 124 Ring seat

[0120] 125 Quartz Window

[0121] 126 Lower electrode

[0122] 127 RF Power Supply

[0123] 131 Solenoid coil

[0124] 241 Liquid Level Sensor

[0125] 242 Control Department

[0126] 243 Pump

[0127] 244 Storage Department

[0128] 1151 Upper cover

[0129] 1152 Base plate.

Claims

1. A plasma processing device, characterized in that: have: a processing chamber for plasma treatment of samples; A high-frequency power source for supplying high-frequency power of microwaves for generating plasma via a waveguide; A magnetic field forming mechanism for forming a magnetic field inside the processing chamber; and Control device, The waveguide comprises: a first circular waveguide filled with a liquid dielectric; and a second circular waveguide disposed outside the first circular waveguide and coaxially with the first circular waveguide, The control device controls the liquid level of the dielectric so that the ratio of the microwave power propagating through the first circular waveguide and the microwave power propagating through the second circular waveguide becomes a desired ratio.

2. The plasma processing device according to claim 1, characterized in that: The waveguide further comprises: a circular waveguide arranged above the first circular waveguide, The inner diameter of the circular waveguide is smaller than the inner diameter of the second circular waveguide.

3. The plasma processing device according to claim 1, characterized in that: The radius of the first circular waveguide is larger than the radius of blocking microwave power when the interior is filled with the dielectric having a relative dielectric constant of 2, and is smaller than the radius of blocking microwave power when the interior is filled with air.

4. The plasma processing device according to claim 1, characterized in that: The radius of the first circular waveguide is larger than the radius of blocking microwave power when the interior is filled with the dielectric having a relative dielectric constant of 2, and is smaller than the radius of blocking microwave power when the interior is filled with air.

5. The plasma processing device according to claim 1, characterized in that: The control device controls the liquid level so that the liquid level becomes high when the ratio of the microwave power propagating in the first circular waveguide to the microwave power propagating in the second circular waveguide is set to be large.

6. The plasma processing device according to claim 1, characterized in that: The control device controls the liquid level according to the correlation between the ratio of the microwave power propagated in the first circular waveguide and the microwave power propagated in the second circular waveguide and the liquid level. The correlation is approximately linear.

7. The plasma processing device according to claim 2, characterized in that: The frequency of the microwave is 2.45 GHz, The radius of the first circular waveguide is larger than the radius of blocking microwave power when the interior is filled with the dielectric having a relative dielectric constant of 2, and is smaller than the radius of blocking microwave power when the interior is filled with air.

8. The plasma processing device according to claim 4, characterized in that: The frequency of the microwave is 2.45 GHz, The waveguide further comprises: a circular waveguide arranged above the first circular waveguide, The inner diameter of the circular waveguide is smaller than the inner diameter of the second circular waveguide.

9. A microwave power control system for controlling microwave power of a plasma processing device, characterized in that: The ion processing device comprises: a processing chamber for plasma treatment of samples; A high-frequency power source for supplying high-frequency power of microwaves for generating plasma via a waveguide; and a magnetic field forming mechanism for forming a magnetic field inside the processing chamber, The waveguide comprises: a first circular waveguide filled with a liquid dielectric; and a second circular waveguide disposed outside the first circular waveguide and coaxially with the first circular waveguide, The liquid level of the dielectric is controlled so that the ratio of the microwave power propagating through the first circular waveguide and the microwave power propagating through the second circular waveguide becomes a desired ratio.

Images